Lift and Axle swap, What should I do?

[jimjafarian]

I thought that I was going to have to sell my 1990 C5, but some unforeseen events have allowed me to keep it and do some upgrades. My plan at the moment is to do a 4in spring lift with ORD custom springs, swap the GM14 bolt(4.54 and either re-gear the 10 bolt up front and wait a couple of years to install a D60 front axle or finish building the D60 I have now, but it needs hubs, Axle shafts, knuckles, and steering components. I don't do any hard rock crawling and would take it easy until I got the D60. I also would have about a month and a half to get this done and then drive 3-5,000 miles. Besides the question of if this is possible, would I need to get new drive shafts for a 4in lift?

 

[mechted]

Generally 4" lift is where you have to install everything in the lift, check the pinion angles, adjust as needed, then check driveshafts for length/operating angle. For the front, there is a 1" spacer available that can usually solve a length issue for about $60. For the rear, you might have to drop the t-case and/or modify the shaft. Sometimes you can get along with your stock shafts. Sometimes you will have to lengthen your stock shafts. Sometimes you will have to go CV in the rear (whole new shaft). Its just hard to say pre-install.

A couple of other things: at a minimum you will need a conversion u-joint for the rear axle, 14bolt uses a 1350 series joint, your current 10bolt(probably) uses a 1310 series. Need to measure that now and get the right conversion joint. If you end up modifying the rear shaft, you can just change the thing out to a 1350 yoke and eliminate the weird u-joint.
You will probably need longer brake lines front and rear if not already modified.

D60's are a little bit taller and longer than 10bolts. So the front will go up about 1/2" inch and the driveshaft will get about 1" shorter. If you are ultimately going this route plan accordingly. If you decide to keep the 10 bolt and sell the 60, also plan accordingly. Thus the 1" spacer being a good option.

So... the answer is it depends. And I really wouldnt plan on doing that modification and then driving it super long distance the next week. Generally give yourself 2-3 weeks to get it all done, then there is a suspension break-in period, where some things might move/settle and need some adjustment. Yes you can do the lift install and rear axle swap in a weekend, but then there are all the smaller things that just end up taking time to resolve: Brake bleeding, pinion angles, driveshafts, new tires, clearances for new tires

 

[jimjafarian]

Generally 4" lift is where you have to install everything in the lift, check the pinion angles, adjust as needed, then check driveshafts for length/operating angle. For the front, there is a 1" spacer available that can usually solve a length issue for about $60. For the rear, you might have to drop the t-case and/or modify the shaft. Sometimes you can get along with your stock shafts. Sometimes you will have to lengthen your stock shafts. Sometimes you will have to go CV in the rear (whole new shaft). Its just hard to say pre-install.

A couple of other things: at a minimum you will need a conversion u-joint for the rear axle, 14bolt uses a 1350 series joint, your current 10bolt(probably) uses a 1310 series. Need to measure that now and get the right conversion joint. If you end up modifying the rear shaft, you can just change the thing out to a 1350 yoke and eliminate the weird u-joint.
You will probably need longer brake lines front and rear if not already modified.

D60's are a little bit taller and longer than 10bolts. So the front will go up about 1/2" inch and the driveshaft will get about 1" shorter. If you are ultimately going this route plan accordingly. If you decide to keep the 10 bolt and sell the 60, also plan accordingly. Thus the 1" spacer being a good option.

So... the answer is it depends. And I really wouldnt plan on doing that modification and then driving it super long distance the next week. Generally give yourself 2-3 weeks to get it all done, then there is a suspension break-in period, where some things might move/settle and need some adjustment. Yes you can do the lift install and rear axle swap in a weekend, but then there are all the smaller things that just end up taking time to resolve: Brake bleeding, pinion angles, driveshafts, new tires, clearances for new tires

The route that I have decided to go is to keep my 10 bolt up front swap the 14 bolt rear, I am going to have a trusted off road shop do the work as they can get it done in a timely fashion. I will have 1-2 months to get it all shook down and I am going to be having some body work done as well before I have to put it on a ship. Also should I do a 6 to 8 bolt conversion on my 10 bolt to make all the rims matching?

 

[wheels87k5]

If you're going to do a 4" lift then go ahead and get a measured CV driveshaft to fit the rear. You won't regret it. If you do a lot of research on everyone who has installed a 4" lift, you will find that some had to get a new driveshaft, and some didn't. The 4" lift is a point where you are pushing the limit on how much driveshaft you have left going into the transfer case so it is better to be safe than sorry.
Does everybody that installs a 4" lift need a new CV driveshaft? In my opinion, YES. It is one of the best mods you can do for any lift over 2". Again, it is only my opinion. There are many 4" lifts without a new driveshaft and are doing great. But that is their choice. New driveshafts are not cheap but it is a good investment.

 

[jimjafarian]

If you're going to do a 4" lift then go ahead and get a measured CV driveshaft to fit the rear. You won't regret it. If you do a lot of research on everyone who has installed a 4" lift, you will find that some had to get a new driveshaft, and some didn't. The 4" lift is a point where you are pushing the limit on how much driveshaft you have left going into the transfer case so it is better to be safe than sorry.
Does everybody that installs a 4" lift need a new CV driveshaft? In my opinion, YES. It is one of the best mods you can do for any lift over 2". Again, it is only my opinion. There are many 4" lifts without a new driveshaft and are doing great. But that is their choice. New driveshafts are not cheap but it is a good investment.

I was definitely thinking that I was going to go with a CV and do the lift as right as possible. This is a modification that I am willing to spend some good money on as I am at the point of no return and will keep the truck as long as possible.

 

[Carcinogen]

Also the 14bolt is going to have a slightly longer pinion length which will help with not needing to lengthen the driveline but also makes the angle worse.