That is awesome! Thanks for the pic Chris. I think i will need this as the TT setup i have it so short!
I should point out that the credit for simple solutions to oft-complicated ideas like these goes to Mark who looks after the cars
^^^^^^^^ I will back this up; Mark @ C.A.R is a very clever bloke and always comes up with great solutions to problems. I couldnt recommend him enough.
Is there a preferred sifter for the 02j? I know I will have to modify a stock one, but are some better than others? God I love this forum. I will be paying for a membership asap.
Later 02J g/boxes come with a different shift tower that connect to different cable connections compared to early stuff. So you either use a Polo, Golf 4 or Audi A3 shifters.
I use the standard 02J shifter as well, with a short shifter. For the cost vs a motorsports shifter, it's a no brainer.
I am going to use mk5 shifter with my 02S in mk2. looks similar to late 02J. And I am doing a DIY short shifter.
Some very valid points on this thread. I look at box/ratio's like this; Power/torque, Rev range,to calculate where the above comes in and to give a speed ratio in any gear. track or road use. Power to weight ratio. 02J with a 3.3 or 3.6 would be a fine starting point,i'd look for a nice happy medium of ratio's so either should do. I'm still a believer that the very long ratio 02A TDI boxes can be turned into a very nice 4 + E with overdrive (4 on track with 5th for the motorway) 140+ mph in 4th should be enough for most tracks and lower gears will be able to be held longer,so meaning less gear changes per lap. As said above though,you've just got to try it 1st then "review" the situ after.
I agree with everything you said Tommy. One thing that people havent mentioned is turbo spooling. With a close ratio box you never drop rpms enough to get out full boost. With a longer box it might be possible to shift yourself out of boost with a bigger laggy turbo. This is just a hunch and may not hold any water in real life. A properly sized turbo should be spooling early enough that almost any redline shift will keep you above the spool rpm threshold. I like the idea of the TDi box. I would rather work the RPM range than spend my time shifting through very close gears. I found a local Porsche racing shop today who know their way around an 02j. I am very excited about the prospects of finding a relatively cheap 02j and installing a wavetrac diff and freshing up the worn bits , locally. This is a way cheaper option than ordering a prebuilt trans from a supplier on the coast. Now we get down to brass tacks. Apparently there are 2 different versions of the 02j with different shift mechanisms. I realize that there are various models with different ratios but is there a clear Choice of old vs new here? Did Vw improve the box through its production run? I am sorry about all the questions. I am new here and have a backlog of problems that i am working through. Jason
The problem with the 02A TDI gearbox is that the 1st and 2nd will be toooooo short, and then a nice gap with 3rd, 4th and 5th. It should be somewhat near this in km/h 1- 50 2- 90 3- 170 4- 240 5- 300+ So, 1st and 2nd are really short and 5th too tall. After reading a lot, and considering the options, I did a VR6 configuration. CDA (or any regular gasoline gearbox) with a 3.39 FD (from a 02A TDI). I think it's the best I could do. I had the same gearbox with a 4.25FD and 3.69 FD, and I love the 3.39FD the most.
You really need to study your torque curve to determine how the gear spacing would affect if you would drop out of boost or not. Hypothetical case at WOT. Engine produced peak torque @ 4800-5600 rpm, 80% torque @6000rpm and 65% torque at 7000rpm. At a 7000rpm shift with a drop to 6000rpm would, in this case actually put you well right of peak torque than if the vehicle was shfted at 6500rpm and the drop was now to 5500rpm. In such a shift you would be driving the engine in a higher average torque range and have fast acceleration. Of course that is just one high rpm condition that would influence your gearing. You also have the other end of rpm and that is pulling away and quick reacting turbo, resulting in rapid time to max torque response. Too much torque from say 2000rpm with light car and high axle multiplication (gear X FD) could result in wheel spin and slower acceleration. "350bhp" 20v may mean possibly, full boost by ~ 4000rpm and a torque peak of near 5000rpm, depending on turbo. How the curve decays after this will need further study. 3.89 FD with typical later 95 onwards 02A/02J gear spacing i.e. 3.3/1.94/1.31/1.03/0.84 will mean lots of axle torque and very rapid acceleration. That acceleration would depend on trye compond and size, suspension setup and grip. Plus more gear changes. If wheel spin is a problem, perhaps a reduction in overall axle torque to 3.68 FD ( keeping the spacing) or VR6 type 3.39 FD may be an option. This has already susgested.
I think you will find that the first 3 gears of an ASD code TDI box are the same as a CDA only FD differs. So thats approx 1-50 2-70 3-113 4-144 5-210 If changing at about 7000 rpm. 1234 look very nice to me
Do most people here with track cars do their own gearbox rebuilds or do you have local shops do the work? I am thinking about buying a used 02j and installing a diff myslef. I have not rebuilt a gearbox but i could with a good guide.
I believe ASD is: 3,300 1,944 1,308 0,917 0,717 FD I'm not sure, but either 3.3 or 3.15 right? CDA has the following gear rations, correct? 3,3 1,94 1,31 1,03 0,84 FD- 3.64 Well, from my gearbox Calculator I get this, changing at 7k for a 195/50R15 combo: 1- 63,3 2- 107,6 3- 159,4 4- 202,7 5- 248,6 With a "VR6" gearbox you will have: 67,9 115,6 171,1 217,7 266,9 But then again, with a "high in the rev range" turbo, with a TDI gearbox, you would drop to 4k, which could lead you to lose it. My math though, so it could be completely off
Code 1st 2nd 3rd 4th 5th Final ASD 3.300 1.944 1.308 1.091 0.717 3.158 ATA 3.778 2.105 1.345 0.971 0.795 3.684 AYH 3.778 2.118 1.429 0.971 0.837 3.944 AYK 3.778 2.118 1.429 1.029 0.838 3.684 AYL 3.778 2.118 1.429 1.029 0.838 3.684 AYM 3.778 2.118 1.345 0.971 0.756 3.944 CAT 3.778 2.118 1.345 0.917 0.717 3.944 CCM 3.300 1.944 1.308 1.034 0.838 3.389 CDA 3.300 1.944 1.308 1.029 0.837 3.684 copied from the trans FAQ I've run both boxes in road cars before so quite confident my findings are near the mark
