Golf III ITB

[Knestis]

Update...

If anyone wants to know the secret to disabling the steering lock on one of these beasts, let me know. I just finished wasting a week of my life getting it worked out.

I also got all of the goo out of the floors (although not the tunnel). It's like those Macintosh carmels from Canada: If you try to push it around, it just bends but if you whack it, it breaks and comes out reasonably easily. Except for where it has been kept gooey by the exhaust heat, where it requires a propane torch and scraper. GoofOff takes the residue off really well - with a 3M sruffy pad to encourage it - and when you paint the floor with my favorite brush-on Rustoleum, they turn out really niiiice.

I'm still working on the rear ARB solution and think I have a solution.

More to come and I'm keeping track of everything at www.it2.evaluand.com/gti if anyone wants to follow along...

EDIT - Everyone needs to try one of these...



[This message has been edited by Knestis (edited June 08, 2004).]

[This message has been edited by Knestis (edited June 09, 2004).]

[Jason Weaver]

Website is looking great!

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Jason

[theenico]

I guess that Albin's lap times (welded diff) must be an exception.

Personally, I don't like how the Quaife acts like an open diff when you get a front wheel off the ground. I really like clutch types, but since I can't justify the price of either, I'll stick with the welded diff.

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Nico
KCRaceware (816) 257-7305
[email protected]

[Eric Parham]

With all that talk about diffs, I guess I should add my experiences and my knowledge, which happen to slightly contradict each other in this case.

Knowledge-wise, Dick Shine is completely correct that a torque-biasing ("TB") differential (e.g., Quaife, Torsen, Peloquin, etc.), which, BTW, is *not* really a "limited-slip", has a theoretical advantage over a clutch-type or any other "limited slip" when trying to maximize the handling of a FWD car (with front steering).

Consider, for example, a locked diff or spool. In a steady-state corner, the inside wheel is turning faster than optimal and the outside wheel is turning slower than optimal. The effect when both front tires have traction is that engine power is wasted and cornering traction is sacrificed since the friction circle dictates that the grip wasted fighting the opposite side tire is unavailable for cornering. If the inside tire loses traction, then the outside tire no longer has to "fight" the inside, but now both longitudinal and transverse traction is sacrificed due to the overloading effect on the tire (e.g., a tire with twice the load will have much less than twice the traction, unless one substitutes a MUCH larger tire, which would have other drawbacks).

A limited slip (e.g., clutch-type), has the same *type* of compromise effects as a locked diff up to the point that the static breakaway torque is overcome, but then the similar dynamic operating torque of the limited slip causes the same negative effects as for the locker, but limits those negative effects to a preset amount (namely, the static breakaway or dynamic operating torques).

A torque-biasing ("TB") differential does not have the above drawbacks (well, actually it does but to a *MUCH* lesser extent). Thus, in a steady-state corner, the ultimate cornering limit will be significantly higher for a FWD (and front-steer) car than for any locked or limited-slip equipped car.

Only where there is virtually no lateral weight transfer or insufficient power to lose traction can a completely open diff compare favorably.

Now, I've driven open, VW Motorsport clutch-type limited slip (thanks Dick , Quaife torque-biasing, and welded diffs all in the same type of car (FWD A1 chassis VW). In my experience, the open diff was always slowest but a good learning tool (even minor mistakes give instant feedback in the form of a spinning tire and/or greatly increased lap time). The clutch-type limited slip was great, but noticeably (in low-powered car) wasted some engine power in steady-state corners (and not so noticeably wasted ultimate cornering grip in tire-limited car). The Quaife was excellent, but eliminated several of my favorite "two-wheel-off" passing and/or safety-margin zones The locked diff needed huge tires and tons of power to turn them...

Conclusion: The Quaife (a torque-biasing diff) is fantastic for time-trials and consistent low-traction conditions (rain, snow, etc.). The spool is unthinkable when both engine power and tire (or wheel) size is limited by rules. The VWM clutch-pack is an in-between compromise that doesn't give up too much (except maintenance) while permitting one-wheel-in-the-dirt passes (which never fail to put a smile on my face) and reasonable performance with inconsistent track conditions. So, as for me, I'll run my VWM clutch-pack more often than my Quaife in IT, even though I realize that it's theoretically worse, as long as I have the time (and parts) to maintain it

[racer14itc]

Question for Mr. Shine:

What is your opinion of the European "pawl and pin" diff, as used/described by Anthony Angioletti in the Kamei B-sedan and GT3/GT4 Rabbit? I have one of those diffs in my GP car right now, and it seems to work well. It's similar to the Quaife in that you have to stay off the curbs, otherwise the inside wheel will spin momentarily until the tires touches the ground again. It seems to lock up very smoothly under power, and unlock smoothly under braking and corner entry, allowing the car to point into the corners.

I've driven open diffs (very early on in my racing career), VWMS limited slip (love it), Quaife (very good, but as I mentioned above you have to keep the inside tire on the ground), and the Euro "pawl and pin" diff. One thing not mentioned about the Quaife is that it is very heavy compared to the other diffs and in low hp cars, there is a small 'flywheel' effect as a result.

So far my fastest lap times in the GP Scirocco have been with the Euro pawl & pin diff.

MC

[D. Shine]

The cam and pawl is really interesting!
The things actually wear too rapidly for me and put a lot of metal in the oil. I suppose they are somewhat of a compromise like a clutch type,with more positive locking and some strange characteristics when in transition.
I have only worked with them a little,so I really cant say with authority how they compare.
I havent seen one in 20 years!

Dick Shine

[racer14itc]

Cam & Pawl - that's it! I bought the diff on a whim, as a backup to my VWMS limited slip and the quaife for the GP car. I knew that this type of diff had been used in VW's in the late 70's and early 80's by Angioletti and others. Interestingly, it was used but there were two BRAND NEW drive plates (the cams) with it as spares!

I had it setup & reassembled properly and have run it in two races this year. At each track I was over a second faster than my previous best. I really figured the newer technology like the Quaife would be faster, but I guess "old school" works sometimes too!

Thanks for the input, Dick!

MC

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Mark Coffin
#14 GP BSI Racing/Airborn Coatings/The Shop VW
Scirocco
Zephyr Race Coaching and Consulting
http://pages.prodigy.net/Scirocco14gp

[Knestis]

That's what we used to call a "ZF" LSD, right, Mark? I could be wrong but I think that the Gemini gearbox that my old rally bud is using now has that type diff rather than the clutch-pack.

K

[Bill Miller]

Mark,

I remember hearing about these things years ago. Who was making them?

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

[Bill Miller]

Kirk (or anyone else that knows), where did you guys source your aftermarket seat rails. I have a friend that's looking to get rails to install a Sparco seat in an A3. TIA for your help.

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

[Knestis]

Toward the end of the summer, I'm might be wanting to sell my RECARO sliding seat mount. It goes on the stock channels and has what are essentially universal brackets on the top, to which the ubiquitous side brackets bolt. It's a little too high for the big guys that I'm going to have in the car for the 13 hour enduro.

K

[Bill Miller]

Keep me posted Kirk. Also, shoot me an email w/ how much you'd like to get for them.

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608

[madrabbit15]

I know you guys like your limited slips but I have yet to drive a fwd car with a limited slip (Dodge, Honda, VW) as fast as one with a welded differential. I love the welded in a vw and if I was to ever build another Fwd car, it would most certainly be a welded. It is a pain in the butt to deal with in the pits or if the car breaks, but otherwise its just plain faster than anything else in the turns and pulling out of the turns. If anything it might hurt in high speed turns but I have run it at Lowes and could not see it to be any disadvantgage over other vw's that had more HP than me. Just my opinion.

[Racescort]

Same here! I welded my diff. and the car seems to drive great. I dont feel any funny movments under braking or turns. It feels real smooth.

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Doug
87 Golf GTI
[email protected]

[Knestis]

Update - Konis, springs, and a whopping great rear bar are going in and it looks like I'll be running the CCPS "enduro" at VIR the first weekend of August, as a test-and-tune.

Someone buy Jason's car and come out and play.

K

[JOESELLSVW]

I dropped my car off at the fabricator to install the cage. I'm pretty much on schedule for the first race over the Labor Day weekend. By the end of the month the cage and suspension will be done. I used the steel sunroof from a 92 Passat to weld into place of the glass unit which I sold on E Bay for $200! I'm also using the factory seat mount as a sliding bracket for my Kirkey seat... I'm psyched that I'll have an adjustable seat for enduro codrivers. I can't wait to scale the car after the suspension goes in. Kirk what does your car weigh? What about the car in the North East? Is it possible to get down to the minimum? JOE

[Knestis]

I understand from Jason that he's sold his car. I didn't get any of the details so don't know if it stayed in the area or not.

News on our front is that we had our ITB debut today at VIR after building and installing struts last night. Removing the interior and floor tar removed 125# and that plus the KONIs, springs (500/450, F/R), and whopping great rear bar made for an instant gain of 5 seconds.

The car is probably faster but I think that I'm personally slower since it now tends toward oversteer rather than slow-but-safe underplow.

More at www.it2.evaluand.com/gti under the Events link.

K

[Knestis]

BTW, the brakes were NOT terrible with the ABS sensors disconnected.

K

[Knestis]

Detail work and development continue at http://www.it2.evaluand.com/gti/build2.php

Besides Joe and myself, where are the other MkIII's that are being developed? Jason's "Fritz" went to OH, and there's the guy in the NE - any contact info for him?

K

[OTLimit]

Chris' new car made it's debut at Mid-America Motorplex this past weekend and brought home 2 checkered flags. It is still rough and needs some tweaking. Pictures soon (but it's yellow with blue, in case you couldn't guess).


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Lesley Albin
Over The Limit Racing
Blazen Golden Retrievers