Maximum transfer case drop? - Off-Road Forums & Discussion Groups
Go Back   Off-Road Forums & Discussion Groups > Chevy and GM > GM Standard IFS Trucks & SUV's

GM Standard IFS Trucks & SUV's All discussion of full sized IFS Trucks, SUV's to include Suburban



Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 10-05-1999, 09:13 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Default Maximum transfer case drop?

After raising my 85 k5 4", I developed a driveshaft vibration from 20-35 mph. I dropped the t-case using the spacers that were already on there and it really made a noticable improvement. I still have a tiny bit of vibration in the 20-25 mph range, so my question is this: How much can I drop the transfer case without screwing anything up in the motor/tranny/t-case/whatever? I plan on shimming it as soon as I find the time and money, but in the meantime I just need a temporary (read: cheap) fix so that I'm not constantly wearing out u-joints.

Thanks,
Rob

Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Sponsored Links
Advertisement
 
  #2  
Old 10-06-1999, 06:58 AM
**DONOTDELETE**
Guest
 
Posts: n/a
Default Re: Maximum transfer case drop?

Sounds to me like you don't have your u-joint angles the same. If your pinion shaft is tilted up at say 6 degrees then your transfer case output shaft should be tilted down by the same amount. If they differ by more than 2 - 3 - 4 degrees, you could have vibration problems and short u-joint life. If you've recently added a lift you may have changed the pinion angle. This might be where you need to add a wedge shaped shim (the thick side most likely needs to go toward the front).

Hope this helps, StevenJ

Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #3  
Old 10-06-1999, 07:42 AM
**DONOTDELETE**
Guest
 
Posts: n/a
Default Re: Maximum transfer case drop?

I bought my 4" lift used and it came with 2 1/2 degree shims that I did not install. I also dropped the t-case. The pinion points almost directly at the transfer case. I have not noticed any vibrations at any speed but I had the same concerns as Rob. One thing I did notice is the the distributor is very close to the firewall. Also my motor mounts are shot. That is the next fix. By dropping the rear of the t-case how will that effect the FRONT driveshaft angles?

Greyghost
77 Jimmy
"Tracers work both ways."
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #4  
Old 10-06-1999, 07:16 PM
Keyboard Implanted
 
Join Date: Sep 1999
Location: San Jose, CA
Posts: 4,086
Thanks: 0
Thanked 0 Times in 0 Posts
Shaggy is an unknown quantity at this point
Default Re: Maximum transfer case drop?

If you drop the rear of the transfer case, the front end will point up more (unless you have one of those rare flexible cases[img]/wwwthreads_images/icons/smile.gif[/img], in which case you have a bigger problem). When the front of the case points up more, it puts more angle on the joint at the front output. However, if you are running a CV joint on the front output there shouldn't be a problem (because with a CV the pinion should be in line with the shaft anyways), unless you are already on the ragged edge as far as the angle is concerned.

<font color=black>Evan</font color=black>
<font color=red>http://contagious-racing.8m.com</font color=red>
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #5  
Old 10-06-1999, 08:09 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Default Re: Maximum transfer case drop?

I installed a drop of 1" first, the shop recommended it but I still wore u-joints fast. I added another 1/2" to it and it seemed better. The final fix was to remove the no-name lift block from the rear and install a Rancho 4" lift block. It had a much better angle on it, and I havent worn out a u-joint since. The lesson I learned was that if the rear shaft is aimed at the t-case, its no good. There has to be a similarity between the 2 angles. Mine were very different, the angle at the diff was near zero, while the angle at the top was probably 30 degrees. Now its fixed I think... just in time to be thinkin about a 6 inch kit!!! LOL
Mike

Thumper 2
85 fullsize Jimmy
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #6  
Old 10-07-1999, 09:09 AM
**DONOTDELETE**
Guest
 
Posts: n/a
Default Re: Maximum transfer case drop?

I have noticed that since I lowered my t-case that there is oil being thrown out of the rear output shaft. I have never seen that happen before.

Big question: How do I lower the engine?

Greyghost
77 Jimmy
"Tracers work both ways."
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #7  
Old 10-07-1999, 12:58 PM
Keyboard Implanted
 
Join Date: Sep 1999
Location: San Jose, CA
Posts: 4,086
Thanks: 0
Thanked 0 Times in 0 Posts
Shaggy is an unknown quantity at this point
Default Re: Maximum transfer case drop?

Your putput seal must be shot, and now that the rear of the case is lower, the fluid level reaches it easier. If you have a slip yoke in the case at the rear output, this is a 20 minute fix. If you have a fixed yoke, it's not too hard, but a little more involved. As far as lowering the engine, you don't without major modifications. There is an easier way to fix your vibration problems. If you aren't running a CV style driveshaft in the rear, that's probably your best bet. You'll have to readjust your pinion angle, but once that's done you shouldn't have any vibration problems. Plus you'll be able to raise the case back up to where it's supposed to be, which will eliminate any need to lower the motor. You can keep the cost down by finding a used CV section at a scrapyard.

<font color=black>Evan</font color=black>
<font color=red>http://contagious-racing.8m.com</font color=red>
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #8  
Old 10-07-1999, 03:34 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Default Re: Maximum transfer case drop?

I think I will pull my spare t-cas apart this weekend and check it out.

Thanks for the info. Any suggestions for a home-made angle finder?

Greyghost
77 Jimmy
"Tracers work both ways."
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
  #9  
Old 10-07-1999, 05:31 PM
Keyboard Implanted
 
Join Date: Sep 1999
Location: San Jose, CA
Posts: 4,086
Thanks: 0
Thanked 0 Times in 0 Posts
Shaggy is an unknown quantity at this point
Default Re: Maximum transfer case drop?

Sears has a magnetic angle finder for about $15. Money well spent.

<font color=black>Evan</font color=black>
<font color=red>http://contagious-racing.8m.com</font color=red>
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiFurl this Post!
Reply With Quote
Sponsored Links
Advertisement
 
Reply

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
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -5. The time now is 09:34 PM.


Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO 3.2.0
Copyright 1994-2009, VerticalScope Inc. // Off Road forums & discussion groups sitemap
side by side | atv | dirtbike | snowmobile | sandsport | competition | land use | Jeep | Toyota | Ford | GM