13 replies to this topic

[mariner]

Among my collection of old car magazines I have a copy of the August 1992 Circle track and racing technology. Now many of you would, I suspect, claim that the US circle track and technology cannot co - exist, however this copy had an interesting article on a "clutchless transmission.

Basically it was cheap and simple and did the job. You took an old two speed GM Powerglide and threw away the torque converter, then replaced it with a short link shaft to the flywheel. So you had left the epicyclic gears, the pumps and the valve body etc. Four holes were tapped in to the valve body to bypass the pump output through an external hose. This hose had a simple valve on it in the cockpit closed by a lever.

So leave the valve open no pump pressure to the clutches due to the bypassing , close the valve and the clutches take up and off you go from a standstill - that simple.

My question is could you take a modern 5 speed auto, throw away the converter nad still do the bypass trick. I assume you could do the gear selection viathe modern electonic controls of the valves.

The benefits are

1) No converter losses.

2) Lower weight than manual + clutch ( possibly)

3) Lots of cheap units in junkyards.

IN THEORY the fact that modern auto's are 5 speed would give a good range of ratios. I don't see it working for a small displacement engine but for a big engine in a light sport/racecar it could do.

[Canuck]

This sounds suspciously like the tech used on dirt-track cars my friends campaign in a series I can't recall the name of. No converter, hydraulic valve, on or off. I might be entirely wrong about the following: I seem to recall they only used a single gear, which is why they used a powerglide. McG and others probably know considerably more.

[mariner]

Given the speed of progress in dirt track racing I am sure it is the same technolgy now as described in Circle track magazine back in 1992!

If it works why not use it......

[McGuire]

Yep, technology has advanced. Unlike the Powerglide, all modern automatics have torque converter clutches to eliminate slippage, and the capability to engage/disengage them whenever you want. So except for weight and rotating mass there is no reason to give up the torque converter.

That said, there is no need for five speeds on a short track oval car so the Powerglide setup as described above remains very popular. Simple, bulletproof, and lighter than anything.

[Greg Locock]

I used to have a magic box that gave me direct manual control of the lock up clutch and a gear selector for our electronic 4 speed trans. You will burn or stretch the clutches very quickly on a modern unit. Much of the calibration in a trans is designed to reduce the loads in the trans.

[desmo]

Thank goodness this isn't about racing cross dressers who've lost their handbags.

[Peter Leversedge]

In 1973 I built a Super Modified With A Chev V8 327 and a manual shift Poweglide trans. I race it in beach racing [ won NZ Beach Racing
Championship Race twice ], hillclimbs [ 9th place NZ Gold Star Hill Climb Series ] Ruapuna Park Speedway [ 1/4 dirt ] & Raceway [ 1 mile
tar seal circuit ] and did a Drag Race meet. I retained the torque converter. It worked well for me. In a standing !/4 it was 1/2 or 1 sec. [ can't remember which now ] slower starting off in high. Some of the late type transmissions have very small clutches in there higher gears as they are not designed for moving a vehicle from a standing start and are restricted for space. The Powerglide has quite a large high clutch as being only a two speed it is not so restricted for space.

[scolbourne]

In 1973 I built a Super Modified With A Chev V8 327 and a manual shift Poweglide trans. I race it in beach racing [ won NZ Beach Racing
Championship Race twice ], hillclimbs [ 9th place NZ Gold Star Hill Climb Series ] Ruapuna Park Speedway [ 1/4 dirt ] & Raceway [ 1 mile
tar seal circuit ] and did a Drag Race meet. I retained the torque converter. It worked well for me. In a standing !/4 it was 1/2 or 1 sec. [ can't remember which now ] slower starting off in high. Some of the late type transmissions have very small clutches in there higher gears as they are not designed for moving a vehicle from a standing start and are restricted for space. The Powerglide has quite a large high clutch as being only a two speed it is not so restricted for space.

Look at the auto gearbox used in RC cars. This is very efficient and really simple. It uses one way bearings and all cogs already engaged. Any cog not providing power will simply spin and the cog providing thrust will lock up by way of a centrifugal clutch.

Once you have the gear ratios worked out the only difficulty is setting the centrifugal clutch to lock at the correct speed. It all works very well in practice and is essential for winning races with these highly tuned peaky engines providing about 1hp per cc (1000hp per litre).

[McGuire]

I used to have a magic box that gave me direct manual control of the lock up clutch and a gear selector for our electronic 4 speed trans. You will burn or stretch the clutches very quickly on a modern unit. Much of the calibration in a trans is designed to reduce the loads in the trans.

Sure, most automatic transmissions (early or recent) require upgrading for serious performance use. For example, Powerglides modified for circle-track use like those above typically start with a heavier input shaft and replace the cast-iron clutch drum with a steel one. The rear pump is removed, the front pump is uprated, and the valve body is modified for throttle control or a third "clutch" pedal. Heavy-duty clutch and sprag plates, etc. Same general pattern follows for most automatics in racing use except Ford, where bellhousing adapters are available.

Your magic box sounds like a transmission-breaking machine.

[carlt]

Thank goodness this isn't about racing cross dressers who've lost their handbags.

The very image came to mind when i read the post title !!

[Canuck]

There are some damaged minds here...

[gruntguru]

Thank goodness this isn't about racing cross dressers who've lost their handbags.

I am relieved to report, that never ocurred to me.

[canon1753]

I think Jerrico used to make a clutchless 4 speed for cup cars to go road racing in the late 80's. I don't know if that is the same set up used today.

[OfficeLinebacker]

Thank goodness this isn't about racing cross dressers who've lost their handbags.

Thank you for giving life to the joke I was toying with in the back of my head when I saw the thread title.