Chevy Astro and GMC Safari Forum banner
1 - 6 of 6 Posts

·
Registered
1997 GMC Safari SLX - AWD
Joined
·
60 Posts
Discussion Starter · #1 ·
I know this topic has been beaten to oblivion but I have a couple specific questions!

Firstly, 1997 Safari AWD with the Borg Warner. Super low mileage, nothing is worn out and nothing vibrated before the lift!

My lift is suspension only. Reindexed keys, s10 springs, adjustable shackles. About 3" front and rear.

1. I have the typical rear pinion vibration, At about 55mph + I get a noticebale one. Now, on my old Jeep the solution was a slip yoke eliminator and double cardan shaft, but I don't think this is available here. I do know you can use 4 degree shims under the leaf perches and I was curious if anyone has used that successfully and which ones they recommend? (stupid me threw out the old ones that came on my S10 leaf springs...)

2. I notice a more aggressive/sharp vibration under hard acceleration right off the line. Say I need to merge really quickly and give it the beans, I will feels a vibration that is only comparable to say the wheels vibrating really quickly and being sharply out of balance (they aren't, but that's the feeling) - Not sure if this is CV angle related, or still rear driveshaft related? Does the pinion angle vibration show up at low speed, hard acceleration?

Appreciate any input!
 

·
Registered
2000 Lifted 4x4 Astro 92 V8-350 Shorty
Joined
·
6,007 Posts
3" torsion lift is EXTREMELY excessive for these AWD vans.
Expect premature cv-axle failures, rougher ride, and possible vibrations.
  • Pinion angle is probably wrong.. corrected with angle shims.
  • Driveshaft angle probably wrong.. needs correcting at both ends.
  • CV-axle angles beyond tolerance. Re-indexed keys are not advised.. No fix
Incorrect pinion angle will most certainly show up as vibration, slow and acceleration.
This is most likely your primary trouble.
Front "body-lift" is the only way to lift without altering front geometry and drivetrain.
Rear lifts are done any number of ways.. and any geometry alterations are correctable.

Did some tweaks to my driveline a couple years ago:
Font Line Musical instrument Titanium Cylinder


Line Rectangle Font Parallel Screenshot


Rear pinion pointing upward is worst possible scenario.
 

·
Registered
1997 GMC Safari SLX - AWD
Joined
·
60 Posts
Discussion Starter · #3 ·
Interesting! So essentially, I would want to get 4 degree shims, and install them under the leafs in a way that will point the yoke of the diff, nose down? (fat end of the shim towards the rear bumper, so to speak)
 

·
Registered
2000 Lifted 4x4 Astro 92 V8-350 Shorty
Joined
·
6,007 Posts
So essentially, I would want to get 4 degree shims, and install them under the leafs in a way that will point the yoke of the diff, nose down?
Are you OFF by "4 degrees"? Pointing "upward"?
Did you take actual measurements?
(no way for us to assume if this number or angle is correct)

The link I provided above showed how it was done.. (how I did mine)
 

·
Registered
1997 GMC Safari SLX - AWD
Joined
·
60 Posts
Discussion Starter · #5 ·
Are you OFF by "4 degrees"? Pointing "upward"?
Did you take actual measurements?
(no way for us to assume if this number or angle is correct)

The link I provided above showed how it was done.. (how I did mine)
Crap! Totally glossed over the link. THAT being said... I dropped my front end down about an inch or so, and all vibrations vanished!

I flipped the balljoints back to normal, camber is back to normal!

Seems the issue was maxing out the re-indexed keys. You were right - totally no bueno!
 

·
Registered
2000 Lifted 4x4 Astro 92 V8-350 Shorty
Joined
·
6,007 Posts
EXCELLENT!!!
Thanks for posting the update.
I hope your solution will be an inspiration to others!
 
1 - 6 of 6 Posts
Top