I should be getting my th400 back from the shop soon and I was wondering if anyone has put one in a 2nd gen and has any pointers. Is there a standard driveshaft length? I changed the rear end to a 12 bolt if that matters. What would be a recommended driveshaft diameter/thickness for a 600 hp smallblock and a 4:56 rear end, 3400 lb car.

 

.i got a 400 in my car,i will measure it and repost it to youi think half the yoke is 1 5/8"

 

Measure. Be sure to check your yoke and make sure it isn't worn. If you can feel a ridge on the side of the yoke where the seal has been ridding, then get a new yoke, also be sure to ask the guy that re built your tranny if he replaced the tail cone housing bushing. Many rebuilders give it a look over and re use it. They wear and unless you measure it you can't really tell by eye balling it that it's worn. Worn bushings and worn yokes can cause drive line vibrations as the bushing supports and holds that end of the shaft on center....spend the money and get new greaseable joints...

You want to get as much yoke and spline contact as you can without bottoming out the yoke in the tranny. As the axle moves up and down the yoke slides in and out. so Ideally if you can get the tranny yoke and the axle yoke to be on the same centerline, then you can measure and calculate the exact length shaft you need to insure max spline yoke contact.

So jack up the front of the car and get it as high off the ground as you can with the back wheel on the ground. If you have air shocks let all the air out. This will load the rear suspension. Slide the yoke all the way in then pull it out an inch. Turn the yoke so the u joint surfaces are going the same direction as the rear axle yoke.

Look at the relationship between the tranny yoke, where the drive shaft would beand the rear axle yoke. Are they close to beingin a straight line? If not, try loading the rear suspension. (Get some friends to sit on the trunk or jack up the rear body a little, I use a laser pointer on a samll square) The idea is to get the relationship between the tranny yoke and rear axle to be as close to in line as you can.once you get this be sure that the tranny yoke is sill 1inch out then measure the distance between the u-joint cup centers.

This gives you the longest shaft length you can use without bottoming out in the tranny.

Seams like alot of work, but this has proven to work very well for me in the past.

I did a chevelle some years back. After we got it running we had some drive shaft vibration problems and some tranny leakage from the rear yoke.We pulled the shaft to have the balance checked and the guy at the shop showedus how bad the yoke was.He also suggested the tranny bushing. He put a new yokeon with new joints and checked the shaft. the balance was good. we changed the bushing/ rear seal and reinstalled. No more leak and most of our vibration went away. We took the chevelle down to his shop to get the tires balanced and he pointed out that the yoke was pretty far out of the tranny (it was more than half way out with the weight on the wheels) So the next pay day we had him build us a new longer shaft the drive line vibration went away.

Are you running sub frame connectors? traction/ ladder bars or the like?

hope this answers you questions.

Greg

 

Thanks guys that info does help the shop didnt start on it yet so I make sure they check the bushing, the frames are tied and I also put a 8 point roll bar in it I didnt put the traction bars in it yet I have a few ideas I might try for the traction set up. What would be a good pinion angle for a drag car multi leaf springs? I might have put to much in it when I installed the leaf spring brackets and might need to shim it up a little.

 

Sounds darn good ....should be a good runner...pinion angle...I'm gonna leave that one for the more experinced drag racers...

on the thicknes use the thickest you can get. What series joints are you use 1330 or 1350?

Greg

 

Now another delema the trans guy said the case lugs inside the trans are broke off trans is junk. Guy I got it from got it from got a some bad news coming his way[:@]... why the hell do people do crap like that the trans guy said there is no way he wouldnot have known(guy had replaced the clutches so he had to know) lucky I had it checked. Plan B might be putting a warmed over 350/th350 in it for now we will have to look at the options April 1st the track opens and the points start so we have to be ready!!!!!

 

Any luck with the trany Griff

g

 

Got pistons rods and stuff coming for the 350 picked up a set of vortecs and have been porting themIll take the th350 out this weekend and have it gone over, block is done.. We are not going to make it by April 1st but the points dont start till May. I want to talk to the guy about the th400 before I buy another.

 

Progress is progess...might be able to find a case for the 400 and swap the guts...

Sounds like you will be ready to play come May.

Keep us posted

G