46 replies to this topic

[OfficeLinebacker]

The other thread with a very similar title (yes this is a bit of a satire thread, what are you going to do about it? Huh?) included some answers that indicated, shall we say, that perhaps some of the early offerings in the automatic transmission market were not up to the high standards one might expect of the respective auto manufacturers.

So, basically, Magoo, what's the WORST automatic transmission Detroit ever put in a car and sold for money?

Edited by OfficeLinebacker, 18 March 2011 - 16:18.

[Fat Boy]

Didn't Hudson or somebody have a slush-box that you had to manually put in first gear and release the clutch on at which point it would take over from there? Are we limiting ourselves to Detroit? The one in our families Honda minivan pretty much sucks.

[OfficeLinebacker]

Didn't Hudson or somebody have a slush-box that you had to manually put in first gear and release the clutch on at which point it would take over from there? Are we limiting ourselves to Detroit? The one in our families Honda minivan pretty much sucks.

No, the question for Magoo regards Detroit cos I get the impression he knows a lot about it.

But I'm sure our Aussie members can weigh in on Toranas and stuff and yes, your Honda minivan one probably sucks pretty hard.

[Magoo]

OLB, there is no such thing as a bad transmission -- only misunderstood transmissions that, all too often, weren't given proper education and guidance in their formative years. They deserve our support and encouragement.

[Greg Locock]

I used to work with BTR on their 4 speed, and have had a tiny amount of experience calibrating the shift schedule in practice, and rather more on the modelling side.

Roughly speaking the complexity of design and manufacture is, in my opinion, greater than that of the engine, which probably makes it the most complex subsystem in the car.

As such I'm not in the least surprised there have been hiccups along the way. In particular pre electronics control must have been a series of tricks.

[Lee Nicolle]

In the last 40 years Traumatics. Before that a lot of them.
And 2 speed autos behind 1100 Corrollas deserve a mention.

[OfficeLinebacker]

OLB, there is no such thing as a bad transmission -- only misunderstood transmissions that, all too often, weren't given proper education and guidance in their formative years. They deserve our support and encouragement.

OK, OK which automatic transmissions rode the short bus to school, and how can we design a special education program for them so that they can go on to live fulfilling, productive lives?

[Magoo]

The one most in need of our compassion might be the AR4 used in the now forgotten (sorry for reminding anyone) Renault 25, Renault Premier Eagle Premier, Dodge Monaco, etc.

[Terry Walker]

BMCs odd Mini and 1100 4-speed deserves a mention. AP wasn't it? Never very satifactory, and got a bad reputation in the States where the selector quadrant didn't look like the standard US one.

But then, BMC was the company which couldn't grasp the notion that cars for San Franciso had to have a different diff ratio to cars for Los Angeles. Instead they had one which was unsuitable for both but pretty good for British lanes. LA cars blew up their engines from over-revving on freeways, while SF cars burned out clutches climbing the hills.

Then there was the DAF infinitely variable Variomatic belt drive.

Wasn't there a Crown Electric way back in the twenties which had, where a gearbox normally is, a huge dynamo, amd behind it a big electric motor, then the usual propshaft. Similar principle I think to the diesel electric locos?

I rate the early two-speed Falcon box rather low. I drove a brand-new 1960 Falcon on the day they were released (I was underage, and unlicenced, by my brother-in-law who had just taken delivery of one was amazingly accomodating.) It was pretty damn sluggish off the line, basically second and third gear ratios equivalent, with the torque converter providing "low". No fireball. More reliable than the 3-speed stick shift box, though, which used to fall apart readily.

Edited by Terry Walker, 21 March 2011 - 07:30.

[Catalina Park]

The AP box is a fantastic little unit, the main problem in the states was the drivers not understanding that the stick had to go into D and not 4, 3, 2 or even 1 to be driven as an automatic.
They also needed regular oil changes as they shared the sump oil with the engine.

I bought a low mileage Morris 1100 Auto a few years back. The auto was showing the usual signs of failure (slipping forward clutch). Most Mini experts will say that there is nothing that can be done and to convert to a manual.
4 hours of work it was back running perfectly.

[24gerrard]

BMCs odd Mini and 1100 4-speed deserves a mention. AP wasn't it? Never very satifactory, and got a bad reputation in the States where the selector quadrant didn't look like the standard US one.

But then, BMC was the company which couldn't grasp the notion that cars for San Franciso had to have a different diff ratio to cars for Los Angeles. Instead they had one which was unsuitable for both but pretty good for British lanes. LA cars blew up their engines from over-revving on freeways, while SF cars burned out clutches climbing the hills.

Then there was the DAF infinitely variable Variomatic belt drive.

Wasn't there a Crown Electric way back in the twenties which had, where a gearbox normally is, a huge dynamo, amd behind it a big electric motor, then the usual propshaft. Similar principle I think to the diesel electric locos?

I rate the early two-speed Falcon box rather low. I drove a brand-new 1960 Falcon on the day they were released (I was underage, and unlicenced, by my brother-in-law who had just taken delivery of one was amazingly accomodating.) It was pretty damn sluggish off the line, basically second and third gear ratios equivalent, with the torque converter providing "low". No fireball. More reliable than the 3-speed stick shift box, though, which used to fall apart readily.

Sorry I am new and replied on the wrong post initialy.

The Daf variomatic was not infinitely variable, that was hype. In fact it has a very narrow ratio range resulting from the design limitations.
In modern Van Doorne versions they always use extra conventional gearing and a reverse, defeating the object of the excercise and adding even more torque loss.
Leyland were well aware of the American limitations like no roundabouts and people only driving in strait lines.
The mini and 1100/1300 were efficient inexpensive vehicles, so comparing them to gas guzzlers is hardly relevent to engineering technology.
Smiths electric was better than the Crown, the Smith used metal filing using a magnetic field for direct engagement.
The Kaiser of 1899 had an electric motor in each wheel (CVT) and lead acid batteries, it was a perfectly useable EV right back then and long before GM bought up all the electric vehicles and infra structure and replaced it all with petrol for the oil barons.

Edited by 24gerrard, 21 March 2011 - 11:43.

[24gerrard]

The AP box is a fantastic little unit, the main problem in the states was the drivers not understanding that the stick had to go into D and not 4, 3, 2 or even 1 to be driven as an automatic.
They also needed regular oil changes as they shared the sump oil with the engine.

I bought a low mileage Morris 1100 Auto a few years back. The auto was showing the usual signs of failure (slipping forward clutch). Most Mini experts will say that there is nothing that can be done and to convert to a manual.
4 hours of work it was back running perfectly.

As you probably know, the forward clutch can be removed without takeing the power unit out of the vehicle.
It has a plastic sleeve over two steel sealing rings on re-assembly that sometimes leave grooves in the caseing resulting in low oil pressure.
These grooves can be repaired by re-sleeving the caseing.
You can also adjust the three bands by removeing the large front plate that holds the oil filter housing. One gasket and one sealing ring.
I think you use a 1/4 spacer and ten pound inches, not sure without looking it up.

[24gerrard]

The one most in need of our compassion might be the AR4 used in the now forgotten (sorry for reminding anyone) Renault 25, Renault Premier Eagle Premier, Dodge Monaco, etc.

Apart from the very early electric system, these units were not bad.
I turned one upside down beefed up the clutches, converted it to clutchflite and used it in a De Tomaso, worked well.
It was the earlier Renault auto for their small cars that had major problems.
Cant remember the name of it but it had a multi ring electric wiper plate on the output shaft and gave endless electrical malfunctions.
The AR4 was known in Europe as the 4139 and the 4141.

[404KF2]

No-one's mentioned the Type 451 smart PRNDL (for USA and Canada only) sequential manual? It's like a fat ugly dude in drag. The clutch even slips to simulate torque converter creep. Stupid or what?

My Type 450 diesel smarts have the European shifter and they're OK, because they're not pretending to be slushboxes. With the paddleshifters they're quite OK actually.

[Kelpiecross]

The AP box is a fantastic little unit, the main problem in the states was the drivers not understanding that the stick had to go into D and not 4, 3, 2 or even 1 to be driven as an automatic.
They also needed regular oil changes as they shared the sump oil with the engine.

I bought a low mileage Morris 1100 Auto a few years back. The auto was showing the usual signs of failure (slipping forward clutch). Most Mini experts will say that there is nothing that can be done and to convert to a manual.
4 hours of work it was back running perfectly.

Didn't the Mini auto have bevel gears rather than the usual epicyclic arrangement?

[NeilR]

Dihatsu Charade 2 speed auto with 3cyl engine...slow!

[24gerrard]

Didn't the Mini auto have bevel gears rather than the usual epicyclic arrangement?

IMO AP A is one of the best auto boxes ever built but destroyed by lack of investment and the demise of BL.
The bevel epicyclic was very strong and could take far more torque than any other gearset, it was also very efficient.
The only problem in the geartrain was the dual bevel planet gears. These were electron beam welded and could under very high torque break the weld and spin, loosing drive. The answer was to drill and pin them before hardening and beam welding.
The selector positions of 1234D or 234D (I think the second was cobbled up to encourage starting in D for those who could not work it out or Americans), was brilliant.
The valve chest designed to achieve this allowed simple modification to electronic actuation of the selector valve so that any type of driver control could be used i.e paddles or buttons. With electronic control over the centrifugal governor, the shifts could be 'dialed' in to occur at set rpm dictated to by a sensor on the rev counter.
I did all this in 1975/6 years before F1 autos and it formed the basis for them. Unfortunately F1 regulations made them continue with the layshaft stepped gearbox, which remains (even in its hyped up dual clutch/shaft versions) a 19th century concept with large torque losses that cannot be done away with even with electronic shift.
I wanted to build a lighter caseing for other applications as the standard AP one was hugely over engineered and heavy but it was not to be.

The oval circuit Hot Rod had a 5 speed version of the modified unit with electronic shift. It had a roller lock dif, Jack Knight drop gears all strait cut with an overall ratio of 5.3;1.
Top speed was 92mph at 9500rpm and it reached this on 9 inch slicks in under 6 seconds. It won all the 1/4 mile oval races it was entered in and World champion Barry Lee tested it in 1976 on the Brands oval. Certain people then wined and dinned me and nicked the ideas which surfaced in the 89 Mansel F1 Ferrari.
However I do have a replacement for the seven speed current F1 gearbox, which is also a KERS, it should be acceptable to the regulations (Charly?) and could form the next generation range of KERS and Hybrid gearboxes. It is patent pending at present and in need of a University sponsored paper for a doctorate.

Edited by 24gerrard, 22 March 2011 - 10:16.

[Kelpiecross]

Didn't the Mini auto have bevel gears rather than the usual epicyclic arrangement?

If I recall further - didn't BL also have an experimental hydrostatic drive Mini and even an experimental steam-powered Mini?

[Catalina Park]

IMO AP A is one of the best auto boxes ever built but destroyed by lack of investment and the demise of BL.
The bevel epicyclic was very strong and could take far more torque than any other gearset, it was also very efficient.
The only problem in the geartrain was the dual bevel planet gears. These were electron beam welded and could under very high torque break the weld and spin, loosing drive. The answer was to drill and pin them before hardening and beam welding.
The selector positions of 1234D or 234D (I think the second was cobbled up to encourage starting in D for those who could not work it out or Americans), was brilliant.
The valve chest designed to achieve this allowed simple modification to electronic actuation of the selector valve so that any type of driver control could be used i.e paddles or buttons. With electronic control over the centrifugal governor, the shifts could be 'dialed' in to occur at set rpm dictated to by a sensor on the rev counter.
I did all this in 1975/6 years before F1 autos and it formed the basis for them. Unfortunately F1 regulations made them continue with the layshaft stepped gearbox, which remains (even in its hyped up dual clutch/shaft versions) a 19th century concept with large torque losses that cannot be done away with even with electronic shift.
I wanted to build a lighter caseing for other applications as the standard AP one was hugely over engineered and heavy but it was not to be.

The oval circuit Hot Rod had a 5 speed version of the modified unit with electronic shift. It had a roller lock dif, Jack Knight drop gears all strait cut with an overall ratio of 5.3;1.
Top speed was 92mph at 9500rpm and it reached this on 9 inch slicks in under 6 seconds. It won all the 1/4 mile oval races it was entered in and World champion Barry Lee tested it in 1976 on the Brands oval. Certain people then wined and dinned me and nicked the ideas which surfaced in the 89 Mansel F1 Ferrari.
However I do have a replacement for the seven speed current F1 gearbox, which is also a KERS, it should be acceptable to the regulations (Charly?) and could form the next generation range of KERS and Hybrid gearboxes. It is patent pending at present and in need of a University sponsored paper for a doctorate.

Now you have got me thinking of sticking an AP Auto in the Cooper S...
What would do to an AP box in a road car? Any tricks I should know?

Is there anything that can be done to the torque converter?

[24gerrard]

On the BL development car and the Cooper S Hot Rod, I replaced the torque converted with a manual clutch.
This needed a number of parts to be made.
A new clutch center made from the turbine center of the original TC, with splines, re-riveted to the clutch plate so as to allow the automatic drop gears to be used. The Hot Rod used special strait cut drop gears from Jack Knight engineering, one offs.
The clutch used was the metro plate with radial torque springs, the mini plate has non and the springs smoothed the shifts.
The oil pump used was the auto, which had the main housing and the rotors cut and ground to half their original thickness.
Without the converter there was no need for high volume oil flow.
New pipe feeds were made to feed the converter oil directly to the gearbox mainshaft lubrication valve, avoiding the now non existant torque converter and the primary drop gear housing modified to allow for this oil flow change.
A spacer was made to mount the clutch release bearing and lever housing to the automatic end cover and some relief fettling done to the housing to fit.
The valve chest was modified with a six position electric positioning sleeve on the end of the selector valve replacing the linkage.
A six position lever/switch was wired through a control unit to the valve positioner.
The governor valve was also modified to take a similar electric positioner wired through a control unit with send switches in the rev counter.
The latter was problematic and the original cable lever operated against a spring was used in the early tests. This was all before ECUs and any computers of course. The cable pre loaded the centrifugal governer and allowed the driver to control the rpm of automatic shifts to plus or minus 500 rpm, not perfect as it would be today with an E/GBCU but acceptable.
The Hot Rod had a special Jack Knight output pinion and diff crown wheel, strait cut and very low ratio. Total with the drops of 5.3;1.
The Diff housing and casing had to be machined to fit the larger diameter crown wheel.
The engine block had to be an automatic 1300, because the oil pick up drilling is not drilled in the auto blocks, it picks up oil through a pipe directly from the gearbox oil gallery rather than the manual through the engine oil galleries. It is possible to build a Cooper S engine out of a 1300 block. The later 1300 blocks are actualy stronger and have slightly more metal to machine when modifying. I usualy made up three steel main bearing caps however with a four bolt center main cap. Vanderval bearings in lead indium that you can no longer get.
I also did extensive modifications of the A series engine, including stroking and over boring to 1430 or even 1445 cc.
1300 cranks (larger end journal diameter) off set ground to increase stroke and nitrided and fitted with S rods in EN40B steel.
The Leyland test car was mini 1000 based (standard engine) and the Hot Rod a 1430cc Cooper S on 1300 auto block.

I also built an S unit used in a Midas for stage rallies very succesfuly and another in a modified Status as a rear engined unit.
My other test chassis for units was a Herridge framed dragster designed to take the mini transverse unit.
There was also a unit under test with a Lotus twin cam engine on the unit and plans for a BDA/R Cox GTM with over 200 bhp.
Power to weight and torque transfer would have been awesome.
Dont forget this is 1974 through to 1977. If we had been able to finance things better it would have been a world beater.
In fact there is still potential today to beat most things.
Makes the current BMW mini look like a kiddy car. Still thats modern life I suppose fit a chip here fit a chip there and brrm brrrm.

[cheapracer]

And 2 speed autos behind 1100 Corrollas deserve a mention.

GM Powerglide (either GM or the licenced Aisan-Warner ones) and did you know the KE30/55 series with 1300cc had a GM Trimatic? - point being the boxes were designed/made originally for big 6's and V8's!

Worst auto I know of is actually my own Mazda 6, clunky changes (check the net for the issues) and you could make a cup of tea while it decides to kickdown, borderline dangerous in some situations and the manual change option is no better, really lets down what is otherwise a very good car. I haven't driven many modern cars that have auto's that think too much.

[Lee Nicolle]

GM Powerglide (either GM or the licenced Aisan-Warner ones) and did you know the KE30/55 series with 1300cc had a GM Trimatic? - point being the boxes were designed/made originally for big 6's and V8's!

Worst auto I know of is actually my own Mazda 6, clunky changes (check the net for the issues) and you could make a cup of tea while it decides to kickdown, borderline dangerous in some situations and the manual change option is no better, really lets down what is otherwise a very good car. I haven't driven many modern cars that have auto's that think too much.

The traumatic finally found an engine that it could handle,,, maybe.
I dont think the 2 speed Toyo glide was a powerglide though.

[Magoo]

Nobody ever accused the Powerglide of being refined, but they were sturdy. To break one you had to be trying pretty hard. Drag racers are still running 2000+ hp through the original design (+ good parts). The transmission has been out of production for 30+ years but I know if you blindfolded me and stuck me inside a PG-equipped vehicle, I could identify it by the front pump whine.

[cheapracer]

Auto's were never my thing but I have had a burning question for a number of years - instead of using a common manual clutch in an auto trans, why couldn't you simply valve/regulate the pump line pressure to initially take up the drive? Say you're in first gear but you bypass/dump the line pressure then bring the pressure back up to engage the clutch pack or band to initially get the car underway and of course when you come to a complete stop you just dump the pressure again.

Why won't that work?

The traumatic finally found an engine that it could handle,,, maybe.
I dont think the 2 speed Toyo glide was a powerglide though.

It was a variation built under licence by Toyota.

Of course the best transmission that Ferrari ever used was a GM TurboHydro 400 in the Ferrari 400.

[Greg Locock]

Auto's were never my thing but I have had a burning question for a number of years - instead of using a common manual clutch in an auto trans, why couldn't you simply valve/regulate the pump line pressure to initially take up the drive? Say you're in first gear but you bypass/dump the line pressure then bring the pressure back up to engage the clutch pack or band to initially get the car underway and of course when you come to a complete stop you just dump the pressure again.

Why won't that work?

It will work. For maybe 50 starts. The bands stretch or wear so much that it would fail rapidly. To do a clutch's job, you need roughly a clutch worth of friction area. I used to have a little box for the EB 4 speed that allowed me to lock the torque converter and then drive it as a manual. There were a fearsome number of bangs and screeches.

A very large part of calibrating a trans is minimising the stress on the bands and clutches, by matching speeds and times.

[Magoo]

Auto's were never my thing but I have had a burning question for a number of years - instead of using a common manual clutch in an auto trans, why couldn't you simply valve/regulate the pump line pressure to initially take up the drive? Say you're in first gear but you bypass/dump the line pressure then bring the pressure back up to engage the clutch pack or band to initially get the car underway and of course when you come to a complete stop you just dump the pressure again.

There are thousands of them running in American circle track racing. Powerglide is the most popular adaptation since it is light and strong, has few moving parts. Just bleed off forward cavity pressure in the valve body... you can use a ball valve operating a clutch-type pedal or calibrate the bleed orifice to the selector valve N/D. Much too harsh for road use as Mr. Locock noted above but with no torque converter the rotating inertia is very low, slick on a bullring. Works more or less like a two-speed I/O box. Just google "direct drive Powergilde" or "circlematic."

[cheapracer]

Greg and Mister Magoo, you've done it again!

Excellent, that covered my next question as well re; clutched autos in operation on the street.

[24gerrard]

There are thousands of them running in American circle track racing. Powerglide is the most popular adaptation since it is light and strong, has few moving parts. Just bleed off forward cavity pressure in the valve body... you can use a ball valve operating a clutch-type pedal or calibrate the bleed orifice to the selector valve N/D. Much too harsh for road use as Mr. Locock noted above but with no torque converter the rotating inertia is very low, slick on a bullring. Works more or less like a two-speed I/O box. Just google "direct drive Powergilde" or "circlematic."

Just place a radial spring shock absorber between the engine and input shaft, clutch center plate will do, doesnt have to be a full working clutch.
No more harsh engagement.

[mariner]

Ref Magoo's comments about "circleglides" there was an article on how to do it in an issue of Circle track magazine Augut 1992 ( page 54!!)

As far as shift quality is concerned do modern transmissions recognize altitude and it's effects on power?

At higher altitudes there is less power so for any given RPM or throttle setting the actual torque applied to the trans. will be somewhat different from sea level. As the ECU can track MAP or MAF is this reduction in torque programmed into the trnas shifting algorithms?

[cheapracer]

Reason I asked is because I am toying with various ideas for power transmission.

I thought a 6 speed Ford F6/GM 6T75 might make a nice cheap 5 speed V8 transverse transaxle box for mid engine application if it could be locked up and operated manually.

[cheapracer]

Just place a radial spring shock absorber between the engine and input shaft, clutch center plate will do, doesnt have to be a full working clutch.
No more harsh engagement.

Are you saying it needs the inertia mass or the damping or both?

[OfficeLinebacker]

Are you saying it needs the inertia mass or the damping or both?

Jounce damping.

[cheapracer]

Jounce damping.

Indeed but does it need to be damped or prevented ....

Possibly Greg's example gives a clue as that retained the TQ/flywheel's mass but still jerked so a damping method may be whats required.

Edited by cheapracer, 01 April 2011 - 13:59.

[cheapracer]

Was just looking at this on Wiki ...


Renault 25 automatic transmission

The Renault 25's least durable part was the automatic transmission. Three automatic transmissions were used on R25: MJ3, 4141, both 3-speed, and a new 4-speed AR4, later used on Safrane as AD4/AD8. As a result, most of the 25's in service today are the 5-speed manual because only few autos have survived. The transmission itself was not that bad, poor quality and design of the ATF cooler, however, especially on the later AR4, resulted in this version gaining the title of possibly the worst automatic transmission ever designed. A leaking ATF cooler meant quick transmission death with little or no physical warning, except for ATF stains beneath the vehicle to which not all drivers paid attention or not quickly enough. The results were disastrous. The first transmissions started failing within a few years, that is, while the model was still in production. Renault then prepared a package that was to replace the original poor-quality cooler regardless of vehicle age and mileage. However, the fatal cooler location in front of the right wheel could not be changed. This is the reason why it is extremely difficult, if indeed possible, to find a Renault 25 Automatic with the AR4 transmission today.

[OfficeLinebacker]

Was just looking at this on Wiki ...


Renault 25 automatic transmission

The Renault 25's least durable part was the automatic transmission. Three automatic transmissions were used on R25: MJ3, 4141, both 3-speed, and a new 4-speed AR4, later used on Safrane as AD4/AD8. As a result, most of the 25's in service today are the 5-speed manual because only few autos have survived. The transmission itself was not that bad, poor quality and design of the ATF cooler, however, especially on the later AR4, resulted in this version gaining the title of possibly the worst automatic transmission ever designed. A leaking ATF cooler meant quick transmission death with little or no physical warning, except for ATF stains beneath the vehicle to which not all drivers paid attention or not quickly enough. The results were disastrous. The first transmissions started failing within a few years, that is, while the model was still in production. Renault then prepared a package that was to replace the original poor-quality cooler regardless of vehicle age and mileage. However, the fatal cooler location in front of the right wheel could not be changed. This is the reason why it is extremely difficult, if indeed possible, to find a Renault 25 Automatic with the AR4 transmission today.

[24gerrard]

Was just looking at this on Wiki ...


Renault 25 automatic transmission

The Renault 25's least durable part was the automatic transmission. Three automatic transmissions were used on R25: MJ3, 4141, both 3-speed, and a new 4-speed AR4, later used on Safrane as AD4/AD8. As a result, most of the 25's in service today are the 5-speed manual because only few autos have survived. The transmission itself was not that bad, poor quality and design of the ATF cooler, however, especially on the later AR4, resulted in this version gaining the title of possibly the worst automatic transmission ever designed. A leaking ATF cooler meant quick transmission death with little or no physical warning, except for ATF stains beneath the vehicle to which not all drivers paid attention or not quickly enough. The results were disastrous. The first transmissions started failing within a few years, that is, while the model was still in production. Renault then prepared a package that was to replace the original poor-quality cooler regardless of vehicle age and mileage. However, the fatal cooler location in front of the right wheel could not be changed. This is the reason why it is extremely difficult, if indeed possible, to find a Renault 25 Automatic with the AR4 transmission today.

The problems were not caused by any fault with the transmission.

[Magoo]

Dishonorable mention might also go to the 1942 Liquimatic transmission, available on Lincoln and Mercury models, but not for long. FoMoCo did its best to reel them all back in and only a handful still survive.

[Magoo]

The problems were not caused by any fault with the transmission.

Opinions vary.

[nodrift4me]

The worst one I have seen is one from a Mercedes Sprinter van I had for a while. It was actually a manual gearbox but it had a complex hydraulic system fitted to it, controlled by a computer, to make it work like an automatic. The gear selector was conventional and when you picked D from stationary it would push the clutch in and pick 1st gear. As you accelerated away the clutch would let out smoothly and then at what the computer reckoned the right revs was it'd make a change to 2nd gear and so on. It sort of worked okay but if anything isn't working perfectly on it, it starts doing strange things.
So all the downsides of a manual and automatic gearbox rolled up into one.

[cheapracer]

The worst one I have seen is one from a Mercedes Sprinter van I had for a while. It was actually a manual gearbox but it had a complex hydraulic system fitted to it, controlled by a computer, to make it work like an automatic. The gear selector was conventional and when you picked D from stationary it would push the clutch in and pick 1st gear. As you accelerated away the clutch would let out smoothly and then at what the computer reckoned the right revs was it'd make a change to 2nd gear and so on. It sort of worked okay but if anything isn't working perfectly on it, it starts doing strange things.
So all the downsides of a manual and automatic gearbox rolled up into one.

Sounds awfully like they 'borrowed' the Renault R8 <1965 automatic box.

Oh Wiki has a bit on it ..

http://en.wikipedia....ic_transmission

In 1965, Renault offered an automatic transmission of unique design, developed and produced by Jaeger.
The clutch in the system was replaced by a powder ferromagnetic coupler, while the transmission itself was a three-speed mechanical unit similar to that of the Dauphine—but with synchromesh on all gears.
The system used a dash-mounted push button control panel where the driver could select forward or reverse and a governor that sensed vehicle speed and throttle position.
A "relay case" containing electromagnetic switches received signals from the governor and push bottons and then controlled a coupler, a decelerator to close the throttle during gear changes, and a solenoid to select operation of the reverse-first or second-third shift rail—and a reversible electric motor to engage the gears. The system was thus entirely electromechanical, without hydraulics, pneumatics or electronics.
Benefits included comparable fuel economy to the manual transmission version, and easy adaptability to the car. Drawbacks included performance loss (with only three available gears) and a somewhat jerky operation during gear changes.
The transmission was also used in the Dauphine and the Caravelle.

The problems were not caused by any fault with the transmission.

They say the cooler was the issue but it also mentiones the moment they lost fluid/pressure they self destructed beyond repair. Do you have other experiences with this box?

Edited by cheapracer, 05 April 2011 - 05:13.

[24gerrard]

I have repaired a few what I racall as the Renault 4141 transaxles.
The earlier one was the 4139 I believe at least in the UK.

I also turned one upside down and it was fitted into a De Tomaso Pantera behind a Ford 302.
It had a light caseing which is probably why people reported it as completely unrepairable in many cases. Renault also have a habit of running both steel and teflon sealing rings in what seems to be a 'soft' alloy housing both in gearcasing and sub components. This results in the rings cutting grooves that leed to leakage of oil pressure and resulting clutch slip. The answer is to sleeve the problem but it is expensive. I would rate the power capability of this box in the same area as the smaller American turbo ot torqueflite boxes, although the torque converter sprag and impeller is suspect and I changed that by fitting a dry clutch in the Pantera.
Automatic gearboxes use planetary gear sets and all the components work evenly around the central shafts. Unlike an offset layshaft gearbox the 'burstloads' are even and this is a much stronger way to transfer torque. It also allows a lighter casing, which Renault perhaps overdo. The result is a major breakage failure from potentialy small faults.

[cheapracer]

I also turned one upside down and it was fitted into a De Tomaso Pantera behind a Ford 302.

Thats interesting, what are the advantages of 'flipping' the box?

[Tony Matthews]

Thats interesting, what are the advantages of 'flipping' the box?

Reverse rotation.

[cheapracer]

Reverse rotation.

Indeed, very reverse in fact - 3 speeds of reverse and 1 forward.

The Renault 25 is a front engined North/South setup with the gearbox behind the engine (unlike earlier R4, R6, R16 etc.) and ideal for a mid engine setup with out changing a thing.

Now some boxes you can flip and swap over the crown wheel to the other side to maintain forward motion (as they did for the rear engined DeLorean) but may have the advantage in a very low setup with big wheels of raising the driveshafts to be closer to horizontal - fair enough, but ....

...and this is where I get dizzy, unlike a manual box where all you worry about when you flip a box is the oil breather thats now at the bottom and your new oil level depending on the case shape, this is an automatic gearbox and like an engine has a sump at the bottom where the oil is kept for nourishing the pump and for the oil to be drained back into - this is what I would like to know about as there is no way that flipping an auto is an easy thing - not impossible mind you but things get to such a point where you just simply wouldn't do it.

[24gerrard]

Good point cheapracer, I am trying to remember why we flipped it and how.
I think it was just the trans axle diff part of the unit.
I am not sure if the bolt patern is the same upside down though.
If I remember correctly there were only four studs between the gearbox casing and the diff case.
It did have something to do with the original application being north south with the transaxle 'ahead' of the engine though.

[24gerrard]

You are right cheapracer. The renault 25 did indeed have the auto box behind the engine and would have been a strait instalation in the Pantera.
However, I distinctly remember flipping at least part of the transaxle and fitting a manual clutch in place of the converter.
It must have been another renault application of the transmission.
Not much of a conversion transaxle for a modern v8 instalation though I admit.

[Ian G]

In the last 40 years Traumatics. Before that a lot of them.
And 2 speed autos behind 1100 Corrollas deserve a mention.

The Toyota 2 speed was in a Tiara(forerunner to Corona) in the early 1960's(in Oz),one of our School Teachers had a fully imported one and used to drive us to Sport in one.One particular Oval had a steep hill leading down to it,going home it wouldn't climb the hill with 4 kids in it,we had to get out and walk to the top to get our lift back to School,i can see where the SF hills would come into play with small Auto Euro. cars.