Drive Lines

bronco831 · Jun 17, 2004

I'm gettin ready to install a 6" lift on my '90 Bronco.
I was wondering, do I 100% Have to lengthen my driveshaft? or should it be okay with just tilting the the rear axle? .. I've heard mixed reviews on this :unsure:

Broncoholics · Jun 17, 2004

Yes, the driveline will need to be lengthened. You will not know how much until you get the lift on and measure from the center yoke on the axle to the center yoke of the t-case. You might think the stock one is long enough if you hold it up but when the suspension flexes downward you might pull the driveline apart. Take off your stock driveline and pull it apart, you will see the splines are not too far back in there with limited extention. Plus its nice to have a new driveline when adding a lift. More angle will increase the chance of blowing u-joints. Definately angle the axle towards the t-case.

bronco831 · Jun 17, 2004

awesome, thanks.

How much do you think gettin it legthened will cost? ..

Broncoholics · Jun 19, 2004

Its never cheap when getting driveline work done. I paid $300 each for mine but it was a heavy duty splined shaft driveline. I needed some strength to hold up to my 38.5" Swamper SX's, 5:89 gears and detroit lockers.
A standard driveline with new u-joints will be about $200-250.
Some 4x4 junk yards will let you look around and measure some used ones or have them cut a longer one down and weld it back up. Then take it to the driveline shop and have them ballance it. This is what I did for the front driveline. I took a rear driveline from a F350 so I had the CV joint (double u-joint) on it, cut it and rewelded, then ballanced. You will want a CV on both the front and rear drivelines for no vibration problems with a 6" lift.

bronco831 · Jun 23, 2004

do they both need to be cut and lengthened?
I'm still running stock 3.55's with 33" tires right now, but I will be moving up to 35's with the lift...

I know of people who have lifted theirs without having the drivelines cut and they work fine for them.. but I also know people who've had probs.. and I dont want any probs

Broncoholics · Jun 23, 2004

Exactly, you don't want any extra problems. Doing it right the first time is the way to go. If cash is short then install the lift and then measure to see if it will fit.
Most times you can get away with it but when you go wheeling you can pull the driveline apart when an axle drops in a hole. You should have about 2" of gap (shaft) showing on the driveline so the splines have room to move in and out with the suspension flex. A 4" gap like I'm thinking you will have with a 4" lift then you should have it lengthened some day. I've lost a driveline going 60 mph and it launched the rear of the truck a foot off the ground when the driveline hit the ground. :blink: It came back around again and did the same thing over and over until I stopped. Needless to say the driveline was wasted. b-( This was due to a u-joint breaking but the same thing could happen to your set up. Its best to keep it the correct length. I've heard of some rolling becasue they get out of control when it goes.

jfrbronco · Jun 24, 2004

I did a 6" lift on my 90 without any drive shaft work but I killed alot of u-joints before it was sold
JFR-

4xfan78 · Jun 24, 2004

If you dont stretch the driveshafts you WILL eat alot of u-joints and slip yokes. It will only take having to repair them 1 time and you will have wished you would have done it right the first time. I hade mine done about 1 year ago the rear cost me about $250 only because the cv joint was bad and the slip yoke was starting to go bad. The front was copletly redone and it was allmost $300. It really is worth it to just get it done the first time.

BigNasty · Jun 24, 2004

I've lost a driveline going 60 mph and it launched the rear of the truck a foot off the ground when the driveline hit the ground

OUCH!!!

Too bad driveshaft loops are inpracticle on off road vehicles..

One thing to keep in mind is that not all drive shaft shops measure from the same points on the vehicle to make/lengthen/shorten driveshafts, so get with the ones that will do the work and get the way they use so that it's right the first time.

bronco831 · Jun 24, 2004

yeah.. I'm thinkin it should take around $350 or so to get it done.. which isnt TOOO bad.. I'm just kinda bummed/worried about how long it will take.. since this is my only transportation

scrub · Jun 28, 2004

When I bought my 76eb it already had the lift installed. It wasn't shortly after that I was driving down the highway and my rear driveshaft parted at the splines. What a racket! The truck never lifted or anything but it did thrash my transmission and beat the hell out of my brand new dual exhaust. It only cost me $200 to get it extended and balanced. On the other hand my tranny was $500 and I've since put another $250 into my exhaust. Do yourself a favor and get it done right. It will save you $ in the long run.

roofman · Jul 25, 2004

i have a driveshaft safety loop on my truck i used a long limiting strap across the frame by the t-case,blew the u-joint 2 days later fell right on the strap with no probs.
practical?how practical is your safety?