TPI Guy

I bought a TKO and now I have to have the driveshaft cut down a little. I've got the car supported by the suspension at ride height. Now, if I were to get the driveshaft cut so there was no room for travel when the car is sitting at ride height, and I hit a bump, the effective distance between the Rear end and the transmission will decrese, forcing my yoke through my transmission. This would be really bad. So, my queston is:

What is the margin of safety that I need to maintain when having my driveshaft shortened to function at ride height?

or

Is there a better procedure to obtain total driveshaft length?

ScreaminDeamin85Z

i cant remember how my bro's measured theirs, i will ask them how they did it. the way i am thinking is slide the yoke into the trans until it is about 1 inch from being all the way in. take a u-joint and stick it in the rear.now measure from the center of the u-joint to the center of the yokes u-joint. that should be adequate enough so that it wont run into the trans when you go over bumps.

ScreaminDeamin85Z

my bro just replied to my e-mail and he said that he did his like i mentioned except he said the yokes shaft was showing for about 2.5 inches then he measured from u-joint to u-joint and took his driveshaft to the place for shortening. HTH

TPI Guy

Thanks for the reply, but I'm looking for something a little bit more concrete than "about 2.5 inches." I spent 2 grand on a transmission, and I'm not going to take any chances.

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355 c.i.
Dart 180 Heads
Lunati 224/224 cam
Harland Sharp 1.5 rockers
Performer RPM Manifold
Holley 600 cfm double pumper
Hooker Super Competition Headers
Flowmaster Exhaust
Competition Engineering Sub-frame connectors
Tremec TKO
Pro 5.0 Shifter
GM posi 3.42 rear
Hurst Roll Control
13.9@102

SteveSpohn

With the car at ride height, your yoke should be 3/4" to 1" from bottoming out in the transmission.

To measure the length you need, put jack stands under your rear housing (ride height). Push your transmission yoke all the way until it bottoms out, then pull it back 1". Measure the distance from the center of the front yoke u-joint to the center of the pinion yoke's u-joint. That's what you need center to center.

Steve

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Spohn Performance: F-Body Chassis/Suspension Specialists

AlkyIROC

Cool. I needed to know that information for later this winter. I thought it was about 1" and now it's confirmed.

Like Steve said 3/4 - 1". It doesn't have to be exact. 1/4" either way won't hurt it. It's easier to give them a measurement of 54 1/2" than it is to say 54 7/16"

While were on the subject of driveshafts, I need some 1350 yokes without spending a lot for aftermarket ones. Did ford ever install them on the 9" from the factory? Did GM ever use them on TH350's or TH400's?

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87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block (times are for the current engine)

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