Burb driveshaft too short after lift

[texassquarebodies]

This is my first time dealing with a 4wd, let alone a lift. Always been a lowered two wheel guy. I have a 1988 3/4 4x4 burb. I bought a Rough country 6" lift after a month of owning it. After the lift, the rear driveshaft looks like its about too fall out. It sticks out about 2-3" more. My transfer case has not been dropped yet, but my buddy said it might mess up my front drive shaft angles???

The rear blocks are sloped towards the front of the burb. The instructions said nothing about needing a longer driveshaft. Ive got about 20 driveshafts to choose from so I might go that way. Ideas??????

[Doug_J]

TRANSFER CASE LOWERING INSTRUCTIONS
For ½ & ¾T 1980 and later model years on 4” and 6” lifts, the transfer case is lowered by using stock
mounting hardware on the transfer case cross-member.
1. Place floor jack under transfer case cross-member, raise jack until it applies pressure to the cross-member.
Remove stock mounting hardware.
2. Lower floor jack until there is enough space between the cross-member and the frame to install stock spacer
and mounting hardware per the picture. Tighten all hardware.
FRONT CONSTANT VELOCITY U-JOINT STOPS MODIFICATION INSTRUCTIONS
The stops on the front cv u-joint and the stops on the front drive shaft must be modified to obtain maximum
suspension travel on all 4” and 6” lift systems (see diagram below). These stops are designed to prevent the
drive shaft from contacting the road surface in the event of a u-joint failure at the front-end housing.
1. Remove the front drive shaft assembly from the vehicle.
Use a grinder or other suitable tool and remove the
amount of material needed to gain ample u-joint clearance
at the drive shaft stop. (Remove as little material as
possible). About 1/8” of material.
2. With the grinding completed, reinstall the drive shaft and
check the stop clearance by turning the drive shaft

[Doug_J]

http://roughcountry.com/install/145S.pdf
That was all from their web site on the instructions and it shouldnt affect your drive shaft angles except make it better. I know when I droped mine it helped my front drive shaft somewhat anyway because the cv u-joint part was hitting the crossmember, so I put three washers on both bolts of trans/tcase mount to raise it a little and it worked no more rubbing. But in youre case you may need to get drive shafts made.

[special-K]

I never used a transfer case lowering kit for a 6"lift.I agree with your friend,it makes the shorter front shaft even steeper. I also can't see how adding a 1" spacer will make that much difference in your rear driveshaft length. On my '72 K/20 I had to make the driveshaft approx. 2" longer. On my '91 3/4t Suburban with 4" lift I didn't have to do anything to the driveshafts. I have never had to do any driveshaft work on anything with a 4" lift. You just need to find the center of the movement cycle of your rear driveshaft and have it made longer.

[cheepin]

6" lifts usually require longer driveshafts.Plain and simple.There are a couple of options.Call up driveshaft shop and tell them what you have and order new shafts.Or bring in your current shafts along with measurements and have them retube them longer.Or go to the scrapyard and find stock shafts that will work.I believe a long bed single cab with the same drivetrain will work for the rear.

[Doug_J]

Originally Posted by special-K

I never used a transfer case lowering kit for a 6"lift.I agree with your friend,it makes the shorter front shaft even steeper. I also can't see how adding a 1" spacer will make that much difference in your rear driveshaft length. On my '72 K/20 I had to make the driveshaft approx. 2" longer. On my '91 3/4t Suburban with 4" lift I didn't have to do anything to the driveshafts. I have never had to do any driveshaft work on anything with a 4" lift. You just need to find the center of the movement cycle of your rear driveshaft and have it made longer.

I wouldnt buy the transfer case lowering kit. Their should be spacers on the inside of the frame, taken the bolts outta the crossmember take the spacers an put them between the crossmember an the frame.

[texassquarebodies]

Going to try and measure for correct length driveshaft this week. Im off of work but, seem to have other importsnt things to do. Its just a toy, so last on my list. I probably have a drive shaft in my inventory. I will start with that.

Going with 16.5 and Humvee take offs. Im ready to drive it!

[special-K]

Originally Posted by Doug_J

I wouldnt buy the transfer case lowering kit. Their should be spacers on the inside of the frame, taken the bolts outta the crossmember take the spacers an put them between the crossmember an the frame.

I never bought any. Tuff Country supplies them with the lift kit and the ones I have are still in their packages. My point was they are not only unnecessary,they are counter to what is needed. The shorter front driveshaft's angle is greater affected by a lift than the much longer rear. Dropping the transfer case lowers the tail end of the rigid engine/transmission/transfer case assembly which increases the angle on the front shaft. On 67-72 4wds it puts the already crowded to the firewall engine and,especially an HEI,distributor even closer to the firewall. Dropping the t-case also defeats part of the ground clearance we hope to gain by doing a lift in the first place. It's just not a good idea in this range of lift...IMO

Originally Posted by texassquarebodies

Going to try and measure for correct length driveshaft this week. Im off of work but, seem to have other importsnt things to do. Its just a toy, so last on my list. I probably have a drive shaft in my inventory. I will start with that.

Going with 16.5 and Humvee take offs. Im ready to drive it!

Rat own Brutha! Just as interesting (maybe) conversation,when I lifted my '85 Jimmy 4" and also swapped a 14-bolt I was figuring on shortening the driveshaft due to the larger rear. But,it worked out to where the slip yoke sat exactly the same in the transfer case. I was happy! The plan was to shorten the Suburban shaft the lift and axles came out of. I just used a conversion u-joint for now,with plans to still shorten the proper driveshaft.
When I lifted my '72 K/20 Highlander 6" I had to lengthen the rear shaft 2". I have the same lift to go on to my '72 K2500 Sierra. Although,in theory,I should be able to take the shaft and have it shortened 2" in advance so it can go right together. But,that mean ole sucker called prior experience tells me shoulda doesn't always work. So I would wait until it's all in there,then measure the "actual" length. These are those big 4" shafts they used back then and I have another one laying around. I measured this one and it's exactly 2" longer than what's in the truck now! It's either from a '73-75-ish truck,when they still had the fat shaft,or maybe it's the difference between 4spd and automatic. But,I doubt it's the latter,cuz I've swapped from 4spd to auto before and never messed with either shaft. I believe any difference is made up in the t-case adapter. But,anyway,I may be able to just "pop" this driveshaft in there and be done with it! (we'll see)

[Doug_J]

I will say I was thinken the same thing when I did it but I was more worried about strain on the motor mounts but I havent had any issues yet, I had to put washers between my crossmember an trans/tcase because my front drive shaft kept hitting well the u joints did so that did bring everything back up some. When I did space the crossmember like they said It did suck up my reardrive shaft some but it was maybe a 1/4in.

[special-K]

I was wondering how much a dropped t-case helped with the rear drive shaft length.

[Doug_J]

I have the 208 with the slip yoke and it maybe went back in a 1/4in.

[mud slut 350]

In order to do it right your best bet would be to lengthen the driveshafts. you might have to grind off the little ears on the front cv so it will angle down more.

[grayharville]

The best option is to burn the whole rig where it sits.

definetly cheaper than new driveshafts!

[special-K]

Originally Posted by grayharville

The best option is to burn the whole rig where it sits.

definetly cheaper than new driveshafts!

I disagree. I had my driveshaft done for a little over $100 and any 4wd is worth more than that.Oh wait,you were kidding,weren't you.Ok then...LOL?

[texassquarebodies]

I probably have one that is already the right length. I have more square body parts than I know I have, seriously. Ive had my daughter all week, so my burb took a back seat. I will be tinkering on it Monday.

Bought longer rubber brake lines for the front, not $1oo plus dollars either. Try $35. Getting dual steering stabilizers too!!

grayharville works for me part time. We work in my square sancuary. He's only 18. He either wants to burn it or buy it for a dollar

[grayharville]

Just giving you a hard time. Atleast we're finally getting some rain so we can test that thing out!
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[TheWhiteElephant]

Okay, I have to clear up some things here.

First off, lowering the T-case is not meant to help with the length of the driveshafts. On '73 and up trucks, installing the lift will increase the angle of BOTH driveshafts. What this does is create a vibration in most situations, especially in shorter wheelbase vehicles like K5 Blazers or short wheel base trucks. Lowering the T-case will decrease the angle again, therefore eliminating vibration in most cases.

Think about it this way--when you lift a truck, you "push" the frame and t-case up while the differentials stay at the same height. The higher the truck goes, the more severe the angle of the driveshafts. Since the driveshafts connect to the t-case, if you lower the t-case, you will decrease the angle of the driveshafts.

I lowered the t-case on a '79 K5 I had with only 4 inches of lift and felt a noticeable (huge) difference in driveline vibrations. Depending on your truck, you may already have some factory spacers on the t-case mounting bolts on top of the frame/crossmember at the t-case bolts. You just need to relocate these spacers to the bottom of the frame between the frame and crossmember. Very easy one-man job.

Bottom line here is that lowering the t-case decreases the driveshaft angles. By the way, I'm not familiar with the '67-'72 suspensions. Hope this helps.

[Mudder]

I did the same thing as Mando a long time ago. Helped a lot with viberations. I have since replaced the stock spacers with some aluminum blocks.

[special-K]

Originally Posted by TheWhiteElephant

Okay, I have to clear up some things here.

First off, lowering the T-case is not meant to help with the length of the driveshafts. On '73 and up trucks, installing the lift will increase the angle of BOTH driveshafts. What this does is create a vibration in most situations, especially in shorter wheelbase vehicles like K5 Blazers or short wheel base trucks. Lowering the T-case will decrease the angle again, therefore eliminating vibration in most cases.

Think about it this way--when you lift a truck, you "push" the frame and t-case up while the differentials stay at the same height. The higher the truck goes, the more severe the angle of the driveshafts. Since the driveshafts connect to the t-case, if you lower the t-case, you will decrease the angle of the driveshafts.

I lowered the t-case on a '79 K5 I had with only 4 inches of lift and felt a noticeable (huge) difference in driveline vibrations. Depending on your truck, you may already have some factory spacers on the t-case mounting bolts on top of the frame/crossmember at the t-case bolts. You just need to relocate these spacers to the bottom of the frame between the frame and crossmember. Very easy one-man job.

Bottom line here is that lowering the t-case decreases the driveshaft angles. By the way, I'm not familiar with the '67-'72 suspensions. Hope this helps.

67-72s are the same design. I absolutely understand everything involved with lifting a truck. That's why I say,if you think about it,only the rear shaft angle is decreased by spacing the transfer case lower in the frame. The engine,transmission,and transfer case are all mounted together as a rigid unit. This "unit" mounts to the frame in the front using the motor mounts and in the rear using the mount under the transmission/transfer case adapter on top of the crossmember. So,when you lower the rear mount you tilt the unit down to the rear. I can see how this will decrease the angle to the rear shaft. But,I see it cancelling out what it's meant to gain by increasing the angle to the front shaft. It is the shortest shaft with the steepest angle. I have never lifted a K/5 more than 4" and that much angle has not been enough to cause concerns in anything I've driven...no vibration problems,broken u-joints,or even prematurely worn ones. It just seems that raising 4" and dropping 1" isn't really going to help the angle much at all anyway and you lose 1" of high center clearance. If people want to drop transfer cases,I don't care. I'm just saying I have never done it and don't feel I've missed a thing by not.