driveshaft won't fit

[merlin3]

i am in the process of restoring a 72 c10 2wd,when i bought the truck it was lowered,had a 454 TH400,66 chevelle posi rear end.I replaced the trans with a new TH400 from Summit bolted that in same holes with a new mount,replaced the small block frame stands with the correct big block mounts,installed a 509 Merlin,i also lowered the truck with all new parts to were it was when i bought it,installed 5 inch lowering springs and 2.5 lowering blocks in the rear and kept the same rear end.the problem is now my driveshaft is too long,any ideas on what i did wrong?

[chiefcfd]

It looks very close to me in the pics. Is the yoke all the way in the transmission?

[Hawghauler]

You may have noticed three engine mount holes on the crossmember. If you mounted in the rear two holes, you might shift them up to the front two. Then move the trans xmember to accommodate the drive train moving forward almost two inches. If you are already in the forward mounts, you may have to have the shaft shortened.

[merlin3]

thanks,yes the yoke is all the way in the trans. and the mounts are in the forward holes.how much should i have the driveshaft shortened?

[undertaker72]

is your suspension under load or is it lifted or extended , is this on a hoist , or setting as loaded on tires

[merlin3]

the frame is sitting on jack stands mid way and the suspension is hanging.

[undertaker72]

you might try loading or setting it on tires and see were you are at , sometimes when suspension is lifted by like a bumper jack , especialy with coils it changes the angle , it still doesn't have enough travel if your yoke is all the way in , in my opinion , but it will give you a better idea

[kwmech]

When you use the big block stands it will shift the engine rearward about 1 to 1-1/4''. Plus the lowering of the truck will have a small effect on it also

[merlin3]

thanks kwmech that has to be the problem.undertaker72 when i jack up the rear end it will not move,it has no travel,why?

[undertaker72]

it should have a little movement , unless your lowering kit is very super stiff , , ya gotta have a little suspension , in my opinion

[Lees68GMC]

Even though the Turbo 400 cross member, and rubber mount bolts in the same location, there are Turbo 400 models with tail-shaft length differences, also there is a slip-yoke model 400 and a bolted in-place yoke model. The reason this is important is the bolted yoke model requires a drive shaft with a splined / sliding collared end section (looks like the front drive-shaft on a typical 4X4). The slip yoke model is simply a common, one-piece solid drive-shaft like found in a Chevy Turbo 350 equipped car.

With my current set-up I had to have a brand new custom drive-shaft built from scratch, All new including Spicer u-joints $ 363.00

[k_n_browning]

I see the yoke is bolted to the trans.He need a different drive shaft.Looks like the shaft you have is for a slip in yoke trans.Not the bolt in.

[k_n_browning]

oop sorry just seen that was the rearend.I should have looked better.

[brad_man_72]

You changed engine stands.
Changing engine stands an or swapping engine stands from side to side will move the engine around.
The shaft might fit at ride height, still too short to use.
Easiest thing to do is spend the $100 for a cut/weld and ballance for the driveshaft. Especially if it looks like its been modified before. Does it have any weights on it? Have the joints been changed?it looks lke its been painted.




THIS IS WHY YOU CAN'T ASK SOMEBODY ELSE HOW LONG YOUR TRUCKS DRIVESHAFT SHOULD BE!

I know that's not the case this time it just shows how easy it is to move your drivetrain around.

[imjeff]

Does the new transmission have the same tail shaft length as the old one?

[merlin3]

yes the replacement trans.has the same 4 inch tail shaft and the trans mount and crossmember is in same exact spot as before.

[imjeff]

Since your trans crossmember is bolted in the same holes and has the same tail shaft length, the only variables left are angles. New engine horns could have changed the front to back angle as did the new lowering kit. Measure from tail shaft housing to the yoke on your rear end and a driveline shop will know how long to make it. On lowered trucks the driveline angle is so flat that you don't get much change in length through your suspension travel. Probably a combination new suspension components on an already borderline long driveshaft. The fact that your transmission is bolted exactly in the same spot rules out frame perches moving the trans back.

[1970 CST Short Wide]

With all the nice HP stuff you have you'll need a nice new drive shaft to go with it. Go to your local drive shaft shop and have them fix you up.

End of story

[merlin3]

so i just noticed the trans crossmember is bolted to the 2 holes closer to the rear on the pass side lower part of the frame and the driver side is bolted to the 2 holes closer to the front of truck ,hope i can loosen every thing up and move it.thanks for the help imjeff.

[imjeff]

Glad you got it figured out!

Jeff

[merlin3]

thanks Hawghauler i will try that.