The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > General Truck Forums > All 4x4 Tech & Off Roading

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 07-15-2003, 05:33 PM   #1
wildwood
Registered User
 
wildwood's Avatar
 
Join Date: Jun 2003
Location: Calgary AB
Posts: 110
posi question

I've got a '70 GMC K10 with rear posi. When I'm on flat gravel I can light up both tires. But when I'm off-road and I have alot of grip with only one tire, the posi will not force it to spin, and only the other tire spins. I realize that posi is only limited slip and not a locker but I was wondering if anyone has any ideas on how to make it better. Maybe I should add some kind of spacers, stiffer springs, more clutch discs or something to make it work better? Anyone tried any of these? will it affect my street drivability if I mess with it?
__________________
You can't get out if ya don't get in
wildwood is offline   Reply With Quote
Old 07-15-2003, 09:10 PM   #2
Class of 69
Registered User
 
Class of 69's Avatar
 
Join Date: Mar 2003
Location: Stillwater MN
Posts: 1,166
It could be the clutch discs are worn in the posi, causing it to slip as you describe. A good posi will turn both tires, even if one is in mid-air! What sort of foot print does it put down with one tire on the gravel shoulder, and the other on the asphalt? If only the gravel tire spins, you need to rebuild the posi.
__________________
69 GMC K10 ..some restoration required....still..
Class of 69 is offline   Reply With Quote
Old 07-16-2003, 07:06 AM   #3
JIMs70GMC
user # 2756
 
JIMs70GMC's Avatar
 
Join Date: Jun 2001
Location: Chesapeake, Virginia
Posts: 4,612
Yea, sounds like a rebuild to me. There should be a torque spec for the posi. With a power-lock its around 200 ft-lbs to break the clutch pack loose with one tire on the ground and the other in the air. The chassis manual has the procedure.
__________________
1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs
1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX
1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears
1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now.....
1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone.
1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed.

1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm
JIMs70GMC is offline   Reply With Quote
Old 07-16-2003, 01:23 PM   #4
DrMaserati
Village Curmudgeon
 
Join Date: May 2003
Location: Salem, OR
Posts: 75
Before you tear things apart, make sure your really have a problem. Limited-slip differentials require periodic service and an additive to work properly.

Go to the GM dealer and get the genuine GM additive for limited-slip units. Don't rely on the gear oils that claim to already have additive for L-S. Then drain and refill with fresh oil and GM additive. You may find your problem will disappear.
__________________
78 Chevy K30 duallie, 454, TH400
78 IH Scout II, 4X4, 345, 727TF
76 IH Scout II, 4X4, 345, 727TF
65 IH 1200C pickup, 4X4, 345, 4 spd
48 IH KB-8-F, RD-450, 5 spd, 35,000 GVW (a REAL truck)

"Life is too short to drink cheap beer." Harry S. Truman
DrMaserati is offline   Reply With Quote
Reply

Bookmarks


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 02:48 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com