lifted blazer pinion angles

[ssls6]

I have a skyjacker 4" on my 72 K5 and the rear driveshaft pinion angle is bothering me. My driveshaft angle is 16 degrees from level, my transfer case is down 3, and my differential is up 6. This puts the front u-joint at 14 degrees which is a lot.

I've searched this forum and found many people running 4" lifts on their K5s but no one talked about pinion angle. What should I do to fix this? The short wheelbase of the blazer makes pinion angle a tough problem to solve.

I think the 4" skyjacker lift uses 6" lift springs in the back so the blazer has sort of a "muscle car" slope.

[smokekiki]

Read this article...http://www.off-road.com/chevy/reviews/highangle/ Do a search on the net under maximum u-joint angle lots of stuff comes up.I have a 4' lift on my blazer.All spring.I have no problems at all .

[ssls6]

I read the article, good info. So, can I assume everyone here is using a cardan setup with a rotated rear differential to match the driveline angle? If that is true, is pinion lubrication a concern?

Thanks,
Richard

[smokekiki]

No,Ihave a regular joint on each end.Are you sure about the degrees.Do a search and read how to take the measurements.4"is not high enough to cause a problem .6" might need the transfer dropped 1".

[bouncytruck]

That sounds like a lot of angle for a 4" lift. I've got a 6" lift on my '69 and a 4" on my '72 with no problems. Both have blocks in back The '72 is my daily driver.

[ssls6]

Bouncytruck, are you using wedge blocks in the rear?

Thanks,
Richard

[MMGOODIE]

I have been told and have read numerous articles pleading that people stay away from them. They have been considered deadly by Petersons many times over. They have been known to slip or fall out leaving a very loose rearend. Just my .02.

[bouncytruck]

Not sure what mine has exactly. Both lifts were on the trucks when I bought them. I believe the '69 is a Rancho kit and the '72 might be either a Rough Country or Tough Country kit. It looks like smaller blocks with helper springs in the rear.

[Scrubby]

My 72 has a 4 inch tough country lift (all springs). I had to have the rear drive shaft lengthened. When I put it all together I was getting drive line vibes, so I took some angle measurements and ordered a set of 0 rate blocks milled with the angle I needed so the pinion would match the transfercase. The wedge shape blocks also gave me another inch in the rear to fix that saggy butt problem. And, my vibes are gone.

For 4 inch and even 6 inch, I don't think you need a double cardan shaft. Look at this site: ColoradoK5. They are the true experts at lifting K5s.

[J.Lance]

Definitely check out ColoradoK5. Zero rates are an excellent cure for driveline angle. Problem being the Skyjacker lift does "rake" it a little already so you'd have to install them up front too. Hopefully you didn't cut down your u-bolts already. I installed the Skyjacker 4" all spring lift on my old '72 Blazer and didn't have any problems? There were shims already attached to the spring pack and they positioned the rear diff correctly for the lift. Also, although the springs are marked 6", they are actually 6" 73 to 91 springs. (from what I understand) Rear spring lengths are the same, 52", difference being the location of the spring hangers. Spring hangers on a early blazer sit higher on the frame than a later Blazer. Not 100% on this, just what I've heard in the past. When I first got my lift I thought they might be compensating for the weight of the hard top when I saw the stenciled 6" but turned out to not be the case.

[redz 1970 K5]

Had a BAD rear driveline vibration in my K5 when I first got it... I mean BAD... 4" rear springs only. Got a shim from the 4x4 shop(can't remember the angle), but it fixed it right up.

If you are willing to wait, I am pulling the shims soon and adding angled 2" blocks, and you are more then welcome to them for shipping costs only.

Only thing is, less of the center pin contacts the spring perch, and it looks like I have sheared a center pin in back (based on axle location). If I used a new center pin when I installed the shims, it probably would have been fine. These shims go between the spring pack and perch... they don't bolt to the pack like Superlift or others would.

Food for thought. Let me know.

[ssls6]

Thanks for all the good info. I called Skyjackers and they said their kits do not come with wedge blocks. I rechecked my angles using a real tilt gauge.

Transfer case....down 4 degrees
Drive shaft.......up 16 degrees
Differential.......up 12 degrees

That gives 12 degrees of u-joint bend at the transfer case end and 4 degrees of u-joint bend at the differential end. The wedge in my axle looks like a 6 degree block. If I take it out, the rear will match the front (within a couple of degrees) but I've still got a bunch of u-joint flex.

I'm going to take the wedge out but save it. If my vibes get worse, I'll go with a cardian up front and put the wedge back in.

Thanks,
Richard

[vtblazer]

Insteresting that your having a problem with a 4" lift.
I have an all spring 4" lift like some others here and the only thing I did was have the rear drive line lengthened, no problems since.
Good luck and keep us posted on your findings.

[ssls6]

Well, I made some progress today. I lifted the springs off the perches and spun the wedge blocks around 180. Each wedge block is 5 degrees and the final angles ended up like this.

Transfer case....down 4
Drive shaft.......up 19
Differential.......up 5

This is within the guidelines for a 2 ujoint arrangement but with 15 degrees of relative driveshaft angle my ujoints may only have 20-30% of nominal life (I can live with that).

I bet the guy I bought the blazer from put the springs in backwards or spun the wedges around not knowling any better. I won't get a chance to test drive it until tomorrow (waiting on paint to dry).

Thanks for all the help on this.

Regards,
Richard