TurbopigB4C

iTrader: (5)

I did not see it in the sticky so I apologize if this is a topic that has been beat to death. I want to have the close ratio 2.97 2.07 1.43 1.00 .84 .56 in my f-body t-56 and my clutch pedal just dropped to the floor so if its possible its time. Is this possible in an 01 f-body if I buy the gearset? I don't have the money for the DD 7-56 magnuim trans right now so thats out of the question.

redbird555

iTrader: (14)

Well yes in theory it is but you would need everything except basically the case, technically the mm6 gear set is considered close ratio and the m12 s wide. The m12 gear set uses triple cone synchros so its not easy as just swapping the gears out.

If you want the close ratio you can pretty much duplicate the final drive ratio of a m12 gear set with 3.42 rear gears by using your existing mm6 gears and a 3.90 rear gear.

If you really must have the m12 trans, which actually is better because of the improved synchro design then you would be better off selling your t56 and buying one from a gto.

Your clutch pedal dropping to the floor has nothing to do with the trans though, that's a problem with clutch hydraulics as lon as the trans shifted ok its fine.

TurbopigB4C

iTrader: (5)

I do not want to change the final drive ratio it is a road racing car and I will likely be able to hit 155 on the straights. Does the Gto come with 2.97 gearing? I know it may be the master only but with 114k I figure the clutch is probably original and ready to be replaced. Every blue moon it pops out of second so the trans is going to get torn down anyway if I pull it to do the clutch.

redbird555

iTrader: (14)

Yes the gto comes with the wide ratio and the triple cone synchros. The pitfall to the m12 gear set is that the 2-3 gear gap is larger than the mm6 and this causes a lot of gripe especially with gto owners as it causes a higher rpm drop at high speeds so its not as easily recovered.

Also you say that you will top out at 155. Well literally the only gear ratio that will change is 4th because its 1:1 in both gear sets.

2.66 gear with 3.90 gears
1st 2.66=10.37
2nd 1.78=6.94
3rd 1.3=5.07
4th 1=3.90
5th .74= 2.86 final drive

2.97 gear set with stock 3.42
1st 2.97=10.15
2nd 2.07= 7.0
3rd 1.4= 4.77
4th 1= 3.42
5th .84=2.87


As you can see by putting in 3.90 rear gears your final drive with the 2.66 gear set will be the same as the 2.97 with stock gears so nothing will change in top speed from one setup to another. Imo its not wise to swap soley for the gear set because you could simply rebuild yours stronger and then swap gears rather than selling yours and buying a stock gto one to swap in.

TurbopigB4C

iTrader: (5)

With a 3.90 final gear in 4th I would max out at 6800 at 133 mph. I do not use overdrive 5th or 6th on a road course. I would want to keep 150 -155 mph in 4th

redbird555

iTrader: (14)

I assumed stock redline, so yes in this case it would inhibit that. Either way the change over isnt cheap unless you would sell your t56 and then buy a gto unit. At that point though you would have to sell your t56 as damaged and then pay more for a gto one and have that built..

If you talk to tdp they may be able to chnage your gear set while its in for a rebuild. I asked about it once upon a time and I think jason said it would cost me my original "undamaged" gear set and another 400 just to change it over then I would have had to pay for a new input shaft and for the regular rebuild.

It seems like a lot of trouble for the gear set the only real reason I would consider it is for the triple cone synchros. I would think the large shift drop would be a problem in road racing.

TurbopigB4C

iTrader: (5)

My ultimate plan for the car is an ERL ls7 454 with stock like cheater cam for stock exhaust manifolds and cats so the rpm drop should not be an issue at all with all that torque. I may have found a connection for an already built gto trans at a price I am fine with. I would be stoked with a 500hp/500trq stock like drivability daily driver. If I had the 2.97 gearset I could even change my final ratio to a 3.00 rear gear and have the same acceleration as the 2.66 trans but better gas mileage on the freeway down the road after the 454 is in.