[hooki]

hi guys,

I'm installing some 6.5:1 gears in my sierra t-case and I'm at the stage of shimming. I didn't shim the last sierra case I built and I learn't my lesson after dealing with the excessive noise.

So my question is whats the process of shimming the case? There was already an output and input shim in the case with the factory gearing. Should I keep these in the case when working out the new shim thickness?


this is a method which was mentioned on lowrange:

"To determine what size shims are needed, you will assemble the center and the rear case parts without the counter gear assembly or the paper gasket. Squeeze case together until the bearings seat in the bore of the housing, [do not tighten case bolts] then measure the gap between the case halves at both ends with a feeler gauge. The case gap needs to be between 0.36mm/.014in and 0.45mm/.018in. Adjust the gap by adding or subtracting shims. Finish assembling and torque case bolts to factory specs"

does this sound right? Won't the thickness of the paper gasket effect something?

sorry about the noob question
thanks

[303zuke]

You need to remove the old shims to make the measurement, but you will be able to re-use them if they are required. They are appropriate for the length of the shafts (factory ones) that were in the case, but ou will be taking these out and putting different shafts with different adjustments required. Did you order a couple of new shims from Low Range when you got your gears?

That method works correctly, it takes into account the final compressed thickness of the gasket when the case is torqued back together.

And don't expect perfect silence from a correctly shimmed transfer. The gear teeth themselves will still make some noise until they are properly lapped together, which may take a couple of 1000 kms.

[31zook]

303zuke wrote:

You need to remove the old shims to make the measurement, but you will be able to re-use them if they are required. They are appropriate for the length of the shafts (factory ones) that were in the case, but ou will be taking these out and putting different shafts with different adjustments required. Did you order a couple of new shims from Low Range when you got your gears?

That method works correctly, it takes into account the final compressed thickness of the gasket when the case is torqued back together.

And don't expect perfect silence from a correctly shimmed transfer. The gear teeth themselves will still make some noise until they are properly lapped together, which may take a couple of 1000 kms.

X2

[Damo]

FFS Hooki, you don't think anyone has done a tcase rebuild before?

LINKY

[DarkHorse]

Just while I think of it - is this requried for Vit transfers? There's nothing in the destructions for the gears, but there was a shim floating around on top of the front output shaft. Was going to just put it back where it was - am I missing something?

[jono165]

The method of assembling the case with the input and output shaft to determine the shim thickness is the way to go. The method in the factory manual is a bit hard to measure accurately unless you have good equipment. I found it easier to stack all the shims I had in the case and then measure and remove the appropriate amount.

[buzbox]

I'm not sure if the problem I'm having is in relation to this topic but I'll ask here anyways.

Only when decelerating or sometimes just cruising along, My transfer keeps popping into neutral usually at the most inapropriate moment so I have to either roll down a side street or up the gutter. Sometimes it won't go back into 2High so I shove it into 4High to get moving again.

It seems to have started only about 400km of installing them but now it's as frequent as 3 times in a 20km trip to work.

Could it be simply a case of time to change the oil and see if that helps, needs shims? or most probably something else?

[303zuke]

buzbox wrote:

I'm not sure if the problem I'm having is in relation to this topic but I'll ask here anyways.

Only when decelerating or sometimes just cruising along, My transfer keeps popping into neutral usually at the most inapropriate moment so I have to either roll down a side street or up the gutter. Sometimes it won't go back into 2High so I shove it into 4High to get moving again.

It seems to have started only about 400km of installing them but now it's as frequent as 3 times in a 20km trip to work.

Could it be simply a case of time to change the oil and see if that helps, needs shims? or most probably something else?

It could be related to shims, but I'd be more inclined to look at an external cause. Have you done a body lift or have torn transfer mounts? Even twisted a mount bracket? What you describe could just as easily be caused by interference between the front of transfer lever opening in the transmission tunnel and the transfer lever itself. Reduction gears put more torque through the transfer case, and even if you have not ripped a rubber mount or twisted a bracket, the torque on decelleration can cause the box to move more than it used to and put enough pressure on the lever to pop it out of 2H

[buzbox]

Does have a body lift, the lever hole has been cut to suit 4Lo so It's not touching the trans tunnel. It has a new transfer cradle and shifter sheet. The only thing that hadn't been changed is the rubber shifter boot from the lever to the transfer.

I'm just stumped on what it could be considering it was working fine for it's first few hundred kms.

[Blkfxx]

hooki wrote:

"To determine what size shims are needed, you will assemble the center and the rear case parts without the counter gear assembly or the paper gasket. Squeeze case together until the bearings seat in the bore of the housing, [do not tighten case bolts] then measure the gap between the case halves at both ends with a feeler gauge. The case gap needs to be between 0.36mm/.014in and 0.45mm/.018in. Adjust the gap by adding or subtracting shims. Finish assembling and torque case bolts to factory specs"

Rebuilding my case with a fresh counter shaft and bearings today. Can I put the case bolts in to hold the 2 halves together? Because at the moment I'm trying to hold them together with one hand and measure with the other but the gap is always changing. And if i hold one side it lifts the other side making the one I'm trying to measure smaller

Any tips on measuring the gap accurately?


Sorry for bumping an old thread, But figured it'd be good to keep all the info in one thread.

[zukenutter]

I followed the Low Range Offroad guide for measuring. From memory you have to bolt it together evenly to get an accurate measurement and do an average of several gap measurements. Also you do input and output as two separate measurements. I can't remember and I've only done it once so check for yourself.
Page 18 of this guide

http://www.lowrangeoffroad.com/downloads/instructions/STC-651_Samurai-6.5-Transfer-Case-Gear-Kit.pdf