17 replies to this topic

[Top Fuel F1]

Re: Race Tech magazine April/May 2001 issue: Article on the Audi R8 Transmission by Ricardo: Anatomy Of The 2000 Transmission on Page 38 an d 39.

Too bad we can't post this very good illustration. Without having any such good illustration of an F1 gear box I imagine that this Audi design is pretty close to the design concept used in F1, despite that I don't belive Ricardo makes the inner workings for any of the F1 cars. Also Im not sure if the differential portion employs the hydraulic clutch that the F1 cars have.

In any event I know many BB members get Race Tech and am wondering what your comments on this might be.

Rgds;

[Ben]

Hi all,

I worked at Ricardo briefly when they were manufacturing the first few transmissions for the original R8R's. The main difference between the two versions was the original case was aluminium and the shift wasn't a dedicated pnuematic one.

As far as similarities to F1 boxes. In terms of being straight cut dog engagement gears yes, but the centre distance is greater (4" vs about 3.1" in an F1 box).

The original box could run a plate diff, a Viscous diff, a combined visco-mechanical diff, or a spool. This years R8R's ran a visco-mech at Sebring and will probably attempt to do so at Le Mans. Electrohydraulic diffs like F1 cars are illegal in sportscars.

While the Audi box has a pnuematic shift, it is simply an actuator, not a full semi-auto system. All the clutch and rev matching must be done by the driver.

Also the lubrication is wet-sump whereas F1 would be dry. This is to allow the self-containment of the transmission so the unit can be changed in 5 minutes or so.

In summary I would say it is fairly representative but bear in mind the service life means that the Le Mans unit is much beefier (good tech term there!).

Ben

[Top Fuel F1]

Ben:

It seems the only part Audi manufactures is the bell housing. By the way, do you have a copy of this particular Race Tech magazine? If not, in that you were associated with Ricardo, you could order a back copy. The article has several sections to it, taking up to 7 pages.

Rgds;

[Top Fuel F1]

Originally posted by Ben
The original box could run a plate diff, a Viscous diff, a combined visco-mechanical diff, or a spool. This years R8R's ran a visco-mech at Sebring and will probably attempt to do so at Le Mans. Electrohydraulic diffs like F1 cars are illegal in sportscars.

The Race Tech article on the Audi Ricardo gear box also mentions various types and options for differentials:

1. Plate Type (Salisbury)
2. Viscous Coupling (VC)
3. Combined Plate/VC (Viscous-Mechanical, V-M)
4. Option of a Spool (A solid link between the drive shafts)

Last year a reliable source Posted that the F1 cars had a Salisbury Type diff. So I would assume the F1 cars have a Plate Type diff. I'm not sure what the Ricardo VC and V-M terminology involves totally in that the article did not define that. In that there is hydraulic control of some kind involved with the F1 diff it makes one wonder if they have a V-M Type.

[Ben]

F1 diffs are predominantly hydraulically actuated plate diffs. I believe Minardi still ran a Viscous Coupling last year.

Viscous Coupling is the VC technology referred to in the article. A VC is a speed sensitive differential that consists of a series of plates alternately attached to the the two drivehafts surrounded by a highly viscous silicon based fluid. An overspeed situation tries to turn the plates in opposite directions and this in turn shears the fluid causing the resistance and thus the limited slip.

The V-M is a Visco-Mechanical diff and consists of plate and viscous coupling elements.

The problem with a conventional plate diff is that a lot of preload of the plates is required to prevent wheel overspeed if traction is momentarily lost (wheel in the air for example). In this case when the wheel lands the diff can grab and unsettle the car.

The visco-mech uses a viscous coupling to provide preload to the plate diff elements. In effect you get some compromise between the smooth vc and the harsher but more positive plate form of limited slip.

F1 cars don't use Visco-Mechs because they're too bulky and would results in a very wide transmission which is incompatible with the aerodynamic needs of an F1 car. Visco-Mechs have been used successfully in Touring Cars, Sportscars and Champ Cars.

To clarify, the visco-mech and hydraullically actuated plate diff are different technologies.

Ben

[desmo]

Thanks Ben, good explanation.

[Top Fuel F1]

Ben:

Thanks for the good clarification.

Best Regards;

[Ben]

Cheers guys.

I'm currently writing an article on F1 transmissions. It will hopefully include general stuff about gears, bearings, case materials etc, and also some detail on diffs and the torque steer issue.

It should appear on technicalf1.com in the next few weeks. Keep your eyes skinned.

Ben

[Top Fuel F1]

Originally posted by Top Fuel F1
Re: Race Tech magazine April/May 2001 issue: Article on the Audi R8 Transmission by Ricardo: Anatomy Of The 2000 Transmission on Page 38 an d 39.

At the 24 hours of Lemans this week end they were changing the Audi rear ends like under wear. Did anyone hear if it was the R8 gear box failing?

Rgds;

[Ben]

Audi's own site says that the rear end change on the Aiello car in the early hours of Sunday morning was in response to Aiello stating that the box 'wasn't working properly'. Due to the weather and the problems suffered by MG and Bentley with regard to elctronics leads me to think that the selection mechanism could have been the problem.

Not sure about the #1 car. They didn't change until daytime on Sunday so I'm not too sure about that one.

Ben

[Halfwitt]

Originally posted by Top Fuel F1


At the 24 hours of Lemans this week end they were changing the Audi rear ends like under wear. Did anyone hear if it was the R8 gear box failing?

Rgds;

Audi changed gearboxes in less time than it was taking Caddy to get their car restarted. The Audi is a truly amazing car. Superbly reliable, crushingly quick, boringly quiet (unfortunately), strong enough to withstand impacts that would knacker other cars.

They must have a weak spot in the 'box, because they change it regularly in the longer races. However, they are so good at it, they rarely lose a place.

[Ben]

Autosport's Le Mans review has clarified the situation.

The #2 car had it's rear end changed between 2 and 3am because 6th gear had failed.

The #1 car had it's rear end changed at 12:30pm on Sunday after Tom Kristensen began having problems with 4th gear at around 3am.

The problem appears to have been shifting up without being able to use full throttle due to the standing water. I would assume that shifting well below the rev limit was causing problems with the ignition cut that meant the shift was less than smooth.

Ben

[Top Fuel F1]

Originally posted by Halfwitt
Audi changed gearboxes in less time than it was taking Caddy to get their car restarted.

Yes, for one of the changes I thought I heard the guy on the TV say something like 6 or 8 seconds. Did I hear that right? If not what was it?

[nzkarit]

Originally posted by Top Fuel F1


Yes, for one of the changes I thought I heard the guy on the TV say something like 6 or 8 seconds. Did I hear that right? If not what was it?

6-8 min I would say to change a gear box. 6-8 sec would be tyres and fuel and maybe a driver.

[random]

An interesting bit of transmission info was mentioned during the LeMans broadcast during a driver interview. The driver (I forget who) was saying that their transmissions needed to be shifted at full throttle to guarantee the next gear would be properly engaged.

As Ben alluded, this can be a huge problem in the rain. Shifting at full throttle in the wet induces wheelspin and risks a spinout, but not shifting at full throttle risks damaging the gearbox. A catch 22 that may have been the reason for the Audi replacements.

Makes you wonder why they would even want such a transmission in a sportscar likely to be driven in the rain.

[Top Fuel F1]

Originally posted by nzkarit
6-8 min I would say to change a gear box. 6-8 sec would be tyres and fuel and maybe a driver.

Yes, either the announcer on RPM Today either mis-spoke or I did not hear him correctly. Besides I can barely open my hood in 6 sec. Still, ~ 6 min. is very impressive to me.

Rgds;

[MRC]

I don't hink there is anything inherently wrong with the transmission that would not allow it to wrok well in the rain. I would think that a lack of time to fully map the ignition cut at lower throttle positions for all gears would be the major problem of shiting in the rain.

[random]

From what I remember, they were running a rain engine map. But when the tranny is designed to only shift properly at full throttle, you'll always have problems in the rain.

The analogy they made was to an automatic rifle which uses the pressure from one round to advance the next. Just as a misfire will jam a gun or fail to advance the next round, a non full throttle shift could jam the gears or shift halfway.

As the drivers were bemoaning the gearbox, I'd say it's probably not the best choice for sportscars that often see rain events.