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 > 47 - Current classic GM Trucks > The 1969 - 1972 Blazers and Jimmys Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 03-16-2017, 10:13 AM   #76
A1971Blazer
Senior Member
 
A1971Blazer's Avatar
 
Join Date: Nov 2013
Location: East Tennessee
Posts: 618
Re: 1972 Build thread.

Quote:
Originally Posted by prorat56 View Post
Hey I would Like to give my input on you building your rears (I do at least 20 rear diff overhauls and gear changes a year at my shop) Start with the original shims!, set your back lash then check your pattern. I don't own a depth gauge but I have used them and don't like them and think you will be chasing your tail. The gear marking compound will be your friend. Well that's my 2 cents and I hope this helps and makes your job a bit easier.
I agree with this^^^^
The gears are manufactured to a particular dimension as far as spacing and center line are concerned.....but.....the housings are manufactured with certain
tolerances as well...which may or may not be the exact same as what the gears are.
The last set I put in my 12 bolt...I set the depth to exactly what was marked on the pinion gear......it wasn't anywhere close when I checked the pattern...
__________________
1970 Chevrolet K5 Blazer.............
"A little bit's good....a whole lot's better.....and too much barely is enough"
A1971Blazer is offline   Reply With Quote
Old 03-16-2017, 12:03 PM   #77
kehstr
Registered User
 
kehstr's Avatar
 
Join Date: Mar 2015
Location: Utah
Posts: 618
Re: 1972 Build thread.

Quote:
Originally Posted by hemi43 View Post
And one more thing I've learned over the years is do not use synthetic gear lube because you will never get rid of the chatter regardless of how many bottles of additive you put in. On my Blazer I tried using Amsoil's synthetic gear lube because they claimed it was compatible. Well, they were wrong because it sounded like the rear diff was going to break in two. I gave it a few weeks hoping the noise would go away, but it never did. I drained it and put in standard gear lube and a couple bottles of GM limited slip additive, and the problem went away. That was an expensive mistake because Amsoil products aren't cheap.
Is this on a differential with some sort of locker?
__________________
72 GMC highlander nicknamed by my 6-year-old brother "stripes"
http://67-72chevytrucks.com/vboard/s....php?p=7378180
kehstr is offline   Reply With Quote
Old 03-16-2017, 01:06 PM   #78
prorat56
Registered User
 
prorat56's Avatar
 
Join Date: Aug 2016
Location: Northport NY
Posts: 55
Re: 1972 Build thread.

Quote:
Originally Posted by hemi43 View Post
And one more thing I've learned over the years is do not use synthetic gear lube because you will never get rid of the chatter regardless of how many bottles of additive you put in. On my Blazer I tried using Amsoil's synthetic gear lube because they claimed it was compatible. Well, they were wrong because it sounded like the rear diff was going to break in two. I gave it a few weeks hoping the noise would go away, but it never did. I drained it and put in standard gear lube and a couple bottles of GM limited slip additive, and the problem went away. That was an expensive mistake because Amsoil products aren't cheap.
I think he is using trutracks diffs witch have no clutches so no additive needed but I've been leaning away from synthetic's myself. My favorite HD gear oil is Torco race oil GL6 rated. I use it in my Dragweek prostreet car and I've been using the same 9.5" pro gear for 4 season running 7.50s and 6 thousand street miles and they still don't make noise. Also try morpar posi additive is by far the best additive I've ever used.
__________________
72 Chevy K5 CST
prorat56 is offline   Reply With Quote
Old 03-16-2017, 02:36 PM   #79
hemi43
Registered User
 
hemi43's Avatar
 
Join Date: Mar 2015
Location: Newcastle Ontario Canada
Posts: 723
Re: 1972 Build thread.

Quote:
Originally Posted by kehstr View Post
Is this on a differential with some sort of locker?
Yes ! I've had issues with both Auburn style (cones) and clutch style that come in our Blazers when using synthetics. I'm not a chemist, but I assume it has something to do with the friction modifiers much like the difference between Dextron and F type transmission fluid.

On my Blazer, I used Amsoil synthetic in the transfer case as well as the front Diff, but because the front is just an open diff, I had no issues.

What's odd, is that it claims right on the Amsoil tech sheet that their oil is compatible with locking differentials.
__________________
The one that dies with the most tools, wins !

www.dantechfabricating.com
hemi43 is offline   Reply With Quote
Old 03-16-2017, 03:06 PM   #80
kehstr
Registered User
 
kehstr's Avatar
 
Join Date: Mar 2015
Location: Utah
Posts: 618
Re: 1972 Build thread.

Quote:
Originally Posted by hemi43 View Post
Yes ! I've had issues with both Auburn style (cones) and clutch style that come in our Blazers when using synthetics. I'm not a chemist, but I assume it has something to do with the friction modifiers much like the difference between Dextron and F type transmission fluid.

On my Blazer, I used Amsoil synthetic in the transfer case as well as the front Diff, but because the front is just an open diff, I had no issues.

What's odd, is that it claims right on the Amsoil tech sheet that their oil is compatible with locking differentials.
Yeah, my dad had the same problem in his blazer with a Detroit, and he used Schaeffer's synthetic. As soon as he took the synthetic stuff out and put regular 80w-90 in it, it worked perfectly.
__________________
72 GMC highlander nicknamed by my 6-year-old brother "stripes"
http://67-72chevytrucks.com/vboard/s....php?p=7378180
kehstr is offline   Reply With Quote
Old 04-22-2017, 08:07 PM   #81
Spf79
Registered User
 
Spf79's Avatar
 
Join Date: Jun 2016
Location: Washington
Posts: 79
Re: 1972 Build thread.

Hi,

I finally got some time to myself in the garage.

Please take a look at the patterns on my gears, im looking for second opinions... should i run them or do some more shim work?

Pics of the 12 bolt
Attached Images
   
__________________
Full top blazer or bust....

Last edited by Spf79; 04-23-2017 at 01:59 AM.
Spf79 is offline   Reply With Quote
Old 04-22-2017, 08:12 PM   #82
Spf79
Registered User
 
Spf79's Avatar
 
Join Date: Jun 2016
Location: Washington
Posts: 79
Re: 1972 Build thread.

... and the dana 44
Attached Images
  
__________________
Full top blazer or bust....
Spf79 is offline   Reply With Quote
Old 04-22-2017, 10:41 PM   #83
prorat56
Registered User
 
prorat56's Avatar
 
Join Date: Aug 2016
Location: Northport NY
Posts: 55
Re: 1972 Build thread.

Pattern on both look perfect to me.
__________________
72 Chevy K5 CST
prorat56 is offline   Reply With Quote
Old 04-23-2017, 01:38 AM   #84
Spf79
Registered User
 
Spf79's Avatar
 
Join Date: Jun 2016
Location: Washington
Posts: 79
Re: 1972 Build thread.

Quote:
Originally Posted by prorat56 View Post
Pattern on both look perfect to me.
Thanks for looking, the 12 bolt set up really easy... the dana on the other hand took 5 or 6 attempts.

I feel good about the contact patterns, i just wanted some other opinions. Thank you again!
__________________
Full top blazer or bust....
Spf79 is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

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 02:10 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 1997-2013 67-72chevytrucks.com