4 speed gear box ???

[flaboy]

I have a 4 speed gear box in my itc rabitt.4th gear seems to be a dog,won't pull over 5300rpm at roeblings long straight,it will pull well over that in all other gears.

is their a certain number in should look for??



Thanks


Tim

[racer_tim]

www.scirocco.org has a good gear ratio chart

Tranny Code Final 1st 2nd 3rd 4th

GP (3+E from '81) 3.89 3.45 1.75 1.06 0.71
GY (3+E 8/82-7/84) 4.17 3.45 1.75 1.06 0.71
GC (to '80) 3.89 3.45 1.94 1.29 0.97
GC (from '81) 3.89 3.45 1.94 1.29 0.91

So, look at the flat spot on the bell housing directly on the bottom and you will get the tranny code

to get the entire chart, go to the site and search on "ratios"

[Bill Miller]

I assume you're running a 1.6 car. The 1.7's only came w/ 5-spds. Another intersting thing is that the GCR lists the ratios for the GC code to 1980 (which btw, is the last year of the 1.6 cars that are clasified). The also list an alternate where 3rd changes from 1.29 to 1.37. I admit that I'm not all that up on 4-spds, so I don't know if that box exists or not. A 1.37 3rd gear does show up in several of the 020-based 5-speeds, but I don't know if it was ever put in a 4-spd.

[racer14itc]

I assume you're running a 1.6 car. The 1.7's only came w/ 5-spds. Another intersting thing is that the GCR lists the ratios for the GC code to 1980 (which btw, is the last year of the 1.6 cars that are clasified). The also list an alternate where 3rd changes from 1.29 to 1.37. I admit that I'm not all that up on 4-spds, so I don't know if that box exists or not. A 1.37 3rd gear does show up in several of the 020-based 5-speeds, but I don't know if it was ever put in a 4-spd.
[/b]

Bill, some very early GC 4 spds did come with 1.37 third gears. I had a couple of them and used the 3rd gears to build close ratio transmissions for my GP Scirocco.

For an ITC Rabbit/Scirocco, the hot setup was/is to use a GC box with the 1.29 third gear and 0.97 4th. I suspect Tim's car has a later GC box with the 0.91 4th. The numbers he quotes for RPM and speed make sense.

MC

[JamesB]

I have never found a 1.37 GC, but I agree if the 4th gear is a dog he either has a later GC with the .91 or someone swaped it out for a later trans.

[Bill Miller]

Thanks Mark, good to know. As I said, I don't really have any experience w/ the 4-spds. Here's a question for you, can you use that 4.17 R&P out of a GY box in the later 020 5-spds (like a 2H, 4K, or FK)?

James, if he's running the .91 4th, it's not a legal box, per the ratios listed on the spec line.

[JamesB]

I never said he was legal, I am just saying even if his trans code is correct before he ever touched the car he could have a later GC trans in there without knowing.

As for running the 4.17 in the 5 speed, After researching I dont see it possible. the pinion shaft would be too short.

[flaboy]

hey i sure don't want to cheat.i bought the car that way.and if i was going to cheat it wouldn't be in the gear box...more horse power.

anyway let me go and climb under the car and see what i have.


Tim

[flaboy]

Alright the numbers are gc-03037.
Now what?
sounds like could have the right one with the GC letters that were posted by racer-tim

but so far nothing on this car has been the right model year or the correct parts.I'm sure it's been just pieced together with what ever parts the guy could find.


Thanks

Tim

[JamesB]

well, the only think you can do is talk to your local dealer buddy and see if can make sense of the serial number to see if its a newer or older trans.

[Ryan Williams]

Alright the numbers are gc-03037.


The tranny code "numbers" mean that the unit was manufactured March 03, 1977.

It should have the following gear ratios:

GC
1st 3.45
2nd 1.94
3rd 1.29
4th 0.97
Final Drive 3.89

[msogren]

If you shift at 7k outof third , you get about 6k in 4th with any of these trans #.
If he has the econo box out of one of the USA 4spd, he might get the gear that it sounds like ..I think it was 075 4th gear or some strange # with a 367 final. I 'll bet that he has the cruise 4th gear trans, not the 091 or 097. IMHo. MM

[Bill Miller]

If you shift at 7k outof third , you get about 6k in 4th with any of these trans #.
If he has the econo box out of one of the USA 4spd, he might get the gear that it sounds like ..I think it was 075 4th gear or some strange # with a 367 final. I 'll bet that he has the cruise 4th gear trans, not the 091 or 097. IMHo. MM
[/b]


Problem is, shift @ 7k rpm on an ITC motor, is about 700 - 800 rpm past where it's really making any power.

[flaboy]

i am shifting at about 6300 or so in all the other gears.

i just got back from moroso this weekend and i didn't have a head wind like i did at Roebling for my school. and still would only pull about 5300.



thanks for all your help


Tim

[msogren]

I use a 9a gear set with a welded diff and 3.9 final.
You should have less than 700rpm drop into high gear. The 5 speed is leagal isnt it?? If you run sebring, daytona and Roebling the 3.9 is pretty nice with a small 13" tire, some run a 4.2 but I cant see why.
The guy that does my trans is just north of tampa, Jim Loftin, does very nice work for fair price. He is in the CFR monthly adds. I can get his # if you need it tues or call my shop. 352/796/1985 after 10:00
I have a 16V trans to build but it has a 3.67 and not for a 1600 race setup. I may also have a welded 3.9 in the box .
Bill. I was using the 7k as a reference, not a suggested shift point. I shift my 1.8 at about 6300 3-4 and 6200 4-5. But many 1.6 racers run them well up near 7k, all the time, with the G cam late timed.
IMHO MM

[racer_tim]

Looking @ the GCR for the VW ITC Rabbit, and the 1.6 motor car shows 2 ea 4 speed trannies and 1 ea 5 speed tranny. My suggestion would be to get the legal 5 speed box, and put in a 4.46 R&P and be done with it.

[Bill Miller]

I use a 9a gear set with a welded diff and 3.9 final.
You should have less than 700rpm drop into high gear. The 5 speed is leagal isnt it?? If you run sebring, daytona and Roebling the 3.9 is pretty nice with a small 13" tire, some run a 4.2 but I cant see why.
The guy that does my trans is just north of tampa, Jim Loftin, does very nice work for fair price. He is in the CFR monthly adds. I can get his # if you need it tues or call my shop. 352/796/1985 after 10:00
I have a 16V trans to build but it has a 3.67 and not for a 1600 race setup. I may also have a welded 3.9 in the box .
Bill. I was using the 7k as a reference, not a suggested shift point. I shift my 1.8 at about 6300 3-4 and 6200 4-5. But many 1.6 racers run them well up near 7k, all the time, with the G cam late timed.
IMHO MM
[/b]


Yes, the 5-spd is legal, but not the close-ratio one in an ITC car. And how are these folks 'late timing' their cars?

[shwah]

If they decide to take advantage of the rule allowing increased compression, and decide not to utilize the rule that says they MAY reset the cam timing to stock - the timing moves the right way. It can easily be done legally (and by accident).

[flaboy]

since i really don't really know whats been done to the motor..do you think it's just not strong enough to pull past 5300 in 4th gear??


tim

[JamesB]

truely the only way to find out would be to put it on a dyno. But how does it feel at the track, does it still pull over that RPM?

[flaboy]

i beat on it pretty hard at Moroso this weekend and still struggled to get over 5300 in 4th.

pulled ok to 6800 or so in 3rd.


i was fairly comptative with other cars in my class this weekend.pretty much equal to another ITC rabitt with same box in it.

I am beginning to think it may be a weak motor.

Tim

[msogren]

Check the compression and leakdown. If it is under 150 you will run at the back. Might also check timing, often it is too far advanced. Much over 32* might slow it down, IMHO.
check the cam timing quick by finding a true TDC mark and making sure that both lifters are evenly depressed at TDC. You can get pretty close with a caliper as a depth guage, pretty close by eye , after a few times. The TDC mark is in the book, and often not the timing mark, dont get them mixed up. Most of the time it is 10-11mm before the clutch cover bolt. Use a degree wheel to get it right, if you are going to move it.

FWIW I have never had a gear set checked, or compression checked, or cam checked. Most of the ITB cars have the same gear sets from the sound of things and we all shift pretty much at the same spot.Except the 4.22 cars, they are one gear higher and get draft passed some times. But they are fast also. 4.66 is a lot of gear, that works out to be about 105 mph race car .
They all said that I had too much cam on Sat pm. but none put up 100$ to take my bet. my mixture was too rich for the afternoon heat and idled rough. The cam was(still is) untouched VW, set ahead a couple .
I know at ARRC that stuff gets taken apart. Hey, a Mustang ran near or on my times(2:44 sebring) last time out at 2650# ?? I dont think so legally, Maybe tho. It was colder and good for one second probably.
MM

[JamesB]

Funny you mention final drives. I for one can support that a 3.67 SUCKS at summit point. If your running anywhere near competitve lap times your stuck with hitting fuel cut in the worst places.

On my list for next winter is at least a 3.94 final and a diff (as much as dont mind the welded diff, I hate moving around the paddock. I think at that point I will have good shift points. But I did find how to pick up about a half second with turn5 and getting down to 2nd gear just up till I get to 6a with a shift, tap and turn and im much faster out of there and hitting 4th before turn 8.

[msogren]

The 3.9 works well at Summit. I love the welded but it is a lot harder to drive. You have to enter the turn on power. Or the car goes straight.
But the results are worth it, about 3sec at sebring,
after you retrim the car with less rear bar and spring. MM

[JamesB]

I never had that problem, but given its a momentum car i am on the throttle from the moment I turn in through the corner. Diff or welded thats how I been driving cars at summit point.