AFter I lifted it, driveshaft is too short?

[King Crush]

After I lifted it, driveshaft is too long?

I know it does not make sense if you jack something up it should make the driveshaft hafta be too longer, you would think it would be too short. But I put a 6'' Sj on it. The slave cylinder went out and my buddies dad put a new slave cylinder and clutch in it. He said the rear drive shaft is so tight he had to hit it out with a hammer, and the boot was all compressed. He said that prolly what the clunking noise is. So I think I'm gonna hafta have my dad cut off like a 1/4'' and weld it back together. Anyone else ever had this problem? He also said after time since there is so much pressure it could mess up the whole tranny and rear end.

 

[du510]

You've got a '93? So a 2pc driveshaft with the carrier bearing. You're best off swapping out with a 1pc driveshaft from a 98+.

 

[compleckz]

did the slip-spline move freely? i just did my driveshaft u-joints, and i had a bitch of time getting it out, the upper clamp came off the boot at some point, and the splines were mucked up with dried grease and mud..

 

[Forcus]

Yes it does make sense that your driveshaft is now too short. If you think about it, the driveshaft forms the long side of a triangle. The first side is a straight line from the transmission end to an imaginary line that comes straight up from the ground and through the diff yoke. The second side is a line from the end of the first side to the diff yoke. The driveshaft connects the transmission end to the diff yoke and represents the third line. When you added 6 inches to line two, you also changed the length of the long side of the triangle, so now your driveshaft is too short. You can even use Pythagorean theorem to give the estimated length your driveshaft needs extended.

A^2+B^2=C^2 (Stock height / driveshaft length where A is the line parallel to the ground, B is the line perpendicular to the ground, and C is the driveshaft length)

A^2+(B+6)^2=(C+X)^2 (6 inch change to line B adds X to driveshaft length)

Make sure that if you have a slip joint, you have enough engagement as well. Don't want the driveshaft to slip out under full extension.

 

[King Crush]

Thanks, ya the slip joint is completely bottomed out. I think it needs about a half inch taken off it. After I got the rear drive shaft off I locked the lubs and drove it in 4wd in the driveway, and It still clunked. I looked at the front drive shaft and the boot is almost completely compressed, not as bad as the rear though. You think I need to take like a 1/4'' off the front?

 

[King Crush]

You've got a '93? So a 2pc driveshaft with the carrier bearing. You're best off swapping out with a 1pc driveshaft from a 98+.

Ya, I got a 93.

 

[brendank]

Yes it does make sense that your driveshaft is now too short. If you think about it, the driveshaft forms the long side of a triangle. The first side is a straight line from the transmission end to an imaginary line that comes straight up from the ground and through the diff yoke. The second side is a line from the end of the first side to the diff yoke. The driveshaft connects the transmission end to the diff yoke and represents the third line. When you added 6 inches to line two, you also changed the length of the long side of the triangle, so now your driveshaft is too short. You can even use Pythagorean theorem to give the estimated length your driveshaft needs extended.

A^2+B^2=C^2 (Stock height / driveshaft length where A is the line parallel to the ground, B is the line perpendicular to the ground, and C is the driveshaft length)

A^2+(B+6)^2=(C+X)^2 (6 inch change to line B adds X to driveshaft length)

Make sure that if you have a slip joint, you have enough engagement as well. Don't want the driveshaft to slip out under full extension.

You are correct, but that's not the problem. The title states that the driveshaft is too short after the lift, but he then goes on to explain how it's actually too long. I think he just screwed up the title.


Dude, you really need to find out why your driveshaft is too long, because as was explained above, it's geometrically impossible that it was caused by the lift. Your buddy's dad or whatever likely screwed something up. Find out what it is, and fix it.

BTW, changing the driveshaft length is a real dumbass fix unless you know why you're changing it.

 

[Forcus]

I'd like to know too. Doesn't make sense to me that both the front and rear driveshafts are compressed. If anything they should both be extended!

The only way it can happen is if the front axle was moved backwards (which is a possibility, I guess, if the stock arms were used and are pointed downward toward the axle - in which case you'd have zero down travel) and / or the rear axle was moved forwards (which I'm not sure how you'd do unless the springs you got moved it forward). I am thoroughly confused.

 

[brendank]

I'd like to know too. Doesn't make sense to me that both the front and rear driveshafts are compressed. If anything they should both be extended!

The only way it can happen is if the front axle was moved backwards (which is a possibility, I guess, if the stock arms were used and are pointed downward toward the axle - in which case you'd have zero down travel) and / or the rear axle was moved forwards (which I'm not sure how you'd do unless the springs you got moved it forward). I am thoroughly confused.

It's alot more likely that the transmission and transfer case moved down. How? That's for him to figure out.

 

[Sasquatch_Ryda]

Not to mention that there is a ton of people on here running 6" of lift with stock drive shafts front and rear, me being one of them.

 

[King Crush]

opps, brainfart, what I meant is the drive shafts are too long which doesn't make any sence. Check the edit of my first post in this thread.

 

[Thumper113]

Not to mention that there is a ton of people on here running 6" of lift with stock drive shafts front and rear, me being one of them.

Me too. The stock driveshafts have been in mine since '01 with the same lift Crush has. I have the SJ trans crossmember too.

Did the rear diff get pushed too far forward somehow?
Did the front get pulled back somehow?

This isn't making any sense to me when comparing it to my SJ 6" lift.

 

[King Crush]

Ok guys. I jacked the ass end of the truck up and put jack stand under the bumper to see how tight the drive shaft was when the suspension was fully extended. It came out allrgiht. When I went to put it back in I had to go up over it. I don't know why he had trouble getting it out. Anwyay I still don't know what the hell this clunking noise is. All my blots are tight. I checked 'em. I aslos took off the front drive shaft plenty of play. I kinda think it is the radiad arm moving around int trhe bracket or the axle beam moving in the holes. I was thinking of getting those jamed duff polylurothain axle beam bushings. It does this clunking noise when like you come to a stop or roll back and hit the brakes, it's wierd, but I do know it's not suppose to clunk.

 

[mikhail]

my '88 b2 did that once too when i hit the brakes hard , it was a big clunk and felt it too, flet like it was the front suspension. i dont know what it was though, hasnt ever done it since...

 

[samsonitesamsonite]

sounds like radius arms, try tightening them? its possible it could be the pivot bushings, autozone carries the poly bushings, energy suspension bran at that.