Hufenstang

what kind of rwhp can our trannys hold up to in the gt's?

CrazyAl

HP is not the issue. Torque is the issue.

Our transmissions are rated for 380 ft-lb of torque (edit: I am talking about the MANUAL trans). This does not mean that they will break at 381 ft-lb, but it does mean that exceeding 380 will diminish their service life significantly. Of course, the moreTQ you throw at it, the lower the lifetime will be.

Also keep in mind that your suspension/tires are just as much--if not more--of a contriubting factor to the transmission breaking. The stock transmission would be fine even with a 700 ft-lb/ 700 HP engine on street tires...you'll burn up the tires before you could load the transmission enough to break it. But on the other hand, some slicks and a good drag suspension would break something in a heartbeat (probably the diff, as that's the weakest link in the stock driveline)!

Hufenstang

Hey Al, i was thinking of ordering the Tremec 600- which is safe at 600ft/lb of torque it says. I have never done a transmission swap. If i order this would i need a lot of other stuff to make this work, or is that a pretty basic swap. im guessing it comes with everything like clutch ect maybe gears too? or do you switch it all over. im trying to see what its going to cost me heh

mustangman02232

autos or 5 speeds,

not sure on the autos, the t3650s are good till around 380 like stated above, however, if you like powershifting([sm=guilty.gif]-on my buddies mach but same tranny) you will start to develop problems

Hufenstang

oh sorry about that i was talking about a 5 speed, and i do powershift thats why i was wanting to get the Tremec 600, i just dont know how a transmission swap works and if you need addtional items. i figure the new trans already comes with clutch and flywheel to suport the bigger torque

CrazyAl

I am not familar with the 600 so I don't know exactly what would be involved in the swap. But there are several things that need consideration:

1) Does the bellhousing bolt up or do you need an adapter plate. If you need a plate, where you do get it?

2) Clutch. The S197 uses a "tubular" hydrualic throwout bearing. This is unusual and I am 99% sure the 600 is not compatible without modification.

3) The clutch itself: The stock flywheel will work. You may need a new clutch disc with the proper spline count for the input shaft on the 600. While the OEM pressure plate will function, it won't be able to handle this kind of HP, so you pretty much will need a new clutch too.

4) Shifter. The S197 has a very odd body-mounted shifter that is completely unique. The 600 won't have this. So, you need to find some kind of shifter that will work.

5) You will need a new transmission mount & crossmember, though this is easily made from some off-the-shelf steel.

6) You will need a new driveshaft.


The most common swaps in these cars are the T-56 6-speeds, which are used in the the Corvette, Viper, and a couple different Aston-Martins. These are ungodly strong. To give you an idea of the pricing, you can buy a complete rebuilt T-56 for about $2000, though this will not fit up to the Mustang due to the above issues I mentioned. You can get a complete kit ready to drop into your mustang with all of the above parts (new driveshaft, clutch, crossmember, shifter, and all the other parts/mods/etc) for about $5000.

ford4v429

my 2 cents- powershifting near redline aint a good idea...second gear (synchro?) in mine had a rough day at the dragstrip last fall, once in a while itstill kindahangs up just driving normal...saw on newtakoffs or whatever site upin the banner on this site, they have new 5 speeds for 699...thinking I might want to pick up a spare...guys I work with are saying'just take it back' for warranty, but hey- if I broke it, aint right to try and stick ford with it...however, I gottasay I do think the tranny might be a bit light in a couple areas:

1) second dont like powershifting- the day that started it, kinda 'missed second' one time- didnt 'miss' the gate, just felt like it hit a brick wall, and would not go in- even after letting off, it was hard a couple shifts before it started shifting semi-normal again- think the little synchro justcouldnt take the heat, and jammed up(read- expecting discolored pieces of metal in there somewhere). I do think they coulda made this a little tougher- 4~5 powershifts causing damage seems a bit light, even if 'intentional abuse'.Gonna try some royal purple to see if it frees up any(hoping so- read an awful lot of praise for that stuff), but doubt any 'mechanic in a can' is gonna fix anything... if somethings just scored/sticking, it might help- cant hurt anyway, what the heck.

2) the gate to third sucks. never missed it after the first week or two, but the first few days I had it, third gear felt rubbery, hear steeda/others are big improvements, but some say noisy...think a urethane bushing kit-maybe a saleen shorty adapter would be a big improvement, for cheap- and still quiet.

hopefully I dont bust it this summer at the track, but I'll be shifting a bit lower from now on- 5~5.5 should be quicker anyway(I think) as its closer to the torque peak? do think a spare tranny might be smart if only 699, and planning on abusing it a bit. would really like a 6 speed, but would hate to even ask the price...