naasaa

Hi all

Though I haven't had a Mustang for years I turn to this forum for help.

I have a 68 Corvette Convertible with a slight modified 350 engine with manual transmission.
Problem is: With a 3,70 rear and a Muncie 21 close ratio, first 2,20 the gears are to deep for a proper launch.
Further I wouldn't mind to lower the engine RPM for a more comfortable mainroad/highway cruise. So I strongly consider to swap with a T5 WC.
I understand that the T5 WC for 90-93 cobra's are reinforced for a higher torque (310 or 330 ft./lbs)?
If I'm correct they are available with a first gear ratio of 2,94?
Do these boxes have a mechanical speedo drive?

Could someone share their experience with the longivity of these boxes?
Someone who knows where I can find a box including a shaft yoke?

Your comments are much appreciated.

Thanks
Lars

naasaa

Can anyone help me with recommendation to where I can find a good used T5 WC box?

67mustang302

You could just look for a 5 or 6 speed swap out of a later Camaro, F body etc, and get the bellhousing to mate it to a SBC.

naasaa

Thanks for your reply.

The reason that I turned to this forum, as well as considering a box from a Ford, is that I understand that a WC box from a Mustang Cobra is stronger than the T5's from GM.
I don't want to go for a 6 speed as this requires modification to the tunnel.

The said WC box from Cobra's also has a first gear ratio of 2.95 which I believe match's my 3,70 rear end.

Thanks
Lars

67mustang302

Well, I'm not sure on the bolt pattern difference, so I honestly don't know if a Ford box will mate to a GM block, if a bellhousing is available.

Z16

T5 are not the best trans for anything with real torque (302 will hurt a WC T5) a 350 Chevy will really put the hurt to a WC T5 unless you get one from the aftermarket that has been worked to handle power. By the time you spend the cash to get a T5 that can take abuse a TKO 600 is at the same cost, go to the TKO and they can be bought in GM input shaft and bolt pattern (something any Cobra T5 will not). I think you mean that the gearing in your Vette is too tall not too low, if it is too low then the 2.97 in the TKO/T5 will be worse in the case of too low. An M21 with 3.73 in a Vette is a good combination and is common to the 60 muscle cars, it should drive just fine. Another option if you want a deeper first gear is to find yourself a M20 (2.52 1st) wide ratio transmission and it will bolt in just like stock. There is currently a company building M22 with the M20 ratio so that is an option too. Forget the T5 you'll be sorry in the long run.
My Chevelle has a TKO600 behind a 350, and currently 3.08, it is a dream to drive and will be even better once the 3.31's get into it.

naasaa

Thanks for valuable replies.
The T5 is in my favour due to the size which makes it a relative easy fit in a C3 Corvette, as well as the very smooth shift compared to a Tremec, which also requires more modification an already tight trans tunnel..
I will fabricate an adaptor plate to fit the box to the original GM bell housing.
Kiesler makes modified T5 that can handle up to 600 lb-ft. However, I’m aware that this is not a stock Mustang version.
I have the 90-93 WC T5 that’s specified to handle 310-330 lb-ft in my mind. The car is for street driving in summer time only, not for hard racing. However, I expect my 350 to put out close to 400 lb-ft!
What is your experiences with these boxes when the torque limit is exceeded?
Further, do you know where they brake. (Weak point)

Your inputs a greatly appreciated.

Lars