Have bare '91 axle housing. Installing a new True-Trac, with new bearings, and no original shim stack to work with.
What are the preload specs for the Carrier bearings?
Did a search, and read through a boat load of threads, but nothing is mentioned other than "use your original stack". Obviously, that won't work in this case.
TIA
Scott
******Edit
Found source material at the local library that told me three things:
1). Ford uses a special tool for calculating this
2). There is no spec for turnning force
3). You need to first find zero preload and then add 0.006" shims to each side (as per the Mitchell manual.
So here is the short of it:
With the pinion not yet installed, put the stock cast shims one on each side, put the left cap on with bolts finger tight. use a 0.010" (to make the math easier) feeler gauge and start adding shims until there is a slight drag on the feeler gauge. You will need to keep the carrier held to the left and move it around to find the Loosest position and shim to that point. You may also have to change the thickness of the feeler gauge to get a light drag, depending on the shims you have to use.
Once this is reached, take the shims from both sides and add up the total thickness plus the thickness of your feeler gauge. Divide by two and find the least number of shims that equals that number, so you can make two stacks, one for each side. Install the pinion and set pinion depth and preload. Install the carrier and the shim stacks, then measure backlash.
Set the back lash by moving shims from one side to the other as needed. I also found a chart that shows shim thickness to backlash setting.
Backlash Shim change
0.001" ------- 0.002"
0.002" ------- 0.002"
0.003" ------- 0.004"
0.004" ------- 0.006"
0.005" ------- 0.006"
0.006" ------- 0.008"
0.007" ------- 0.010"
0.008" ------- 0.010"
0.009" ------- 0.012"
0.010" ------- 0.014"
0.011" ------- 0.014"
0.012" ------- 0.016"
0.013" ------- 0.018"
0.014" ------- 0.018"
0.015" ------- 0.020"
According to the Mitchell manual the prefered backlash is 0.010"
Add 0.006" shims to each side for preload. As is suggested further down this thread, tap in one of the thicker shims, between two thick shims to keep from damaging a thin shim.
As a side note, I have always set backlash and tooth pattern together.
I'll be doing this (hopefully) tomorrow and will add a new post and/or correct this post. Other than I disagree with shimming to zero (how do you get zero w/out the chance of adding preload?), this makes the most sense in keeping with all the other types of differentials I have done.
*****End of edit
What are the preload specs for the Carrier bearings?
Did a search, and read through a boat load of threads, but nothing is mentioned other than "use your original stack". Obviously, that won't work in this case.
TIA
Scott
******Edit
Found source material at the local library that told me three things:
1). Ford uses a special tool for calculating this
2). There is no spec for turnning force
3). You need to first find zero preload and then add 0.006" shims to each side (as per the Mitchell manual.
So here is the short of it:
With the pinion not yet installed, put the stock cast shims one on each side, put the left cap on with bolts finger tight. use a 0.010" (to make the math easier) feeler gauge and start adding shims until there is a slight drag on the feeler gauge. You will need to keep the carrier held to the left and move it around to find the Loosest position and shim to that point. You may also have to change the thickness of the feeler gauge to get a light drag, depending on the shims you have to use.
Once this is reached, take the shims from both sides and add up the total thickness plus the thickness of your feeler gauge. Divide by two and find the least number of shims that equals that number, so you can make two stacks, one for each side. Install the pinion and set pinion depth and preload. Install the carrier and the shim stacks, then measure backlash.
Set the back lash by moving shims from one side to the other as needed. I also found a chart that shows shim thickness to backlash setting.
Backlash Shim change
0.001" ------- 0.002"
0.002" ------- 0.002"
0.003" ------- 0.004"
0.004" ------- 0.006"
0.005" ------- 0.006"
0.006" ------- 0.008"
0.007" ------- 0.010"
0.008" ------- 0.010"
0.009" ------- 0.012"
0.010" ------- 0.014"
0.011" ------- 0.014"
0.012" ------- 0.016"
0.013" ------- 0.018"
0.014" ------- 0.018"
0.015" ------- 0.020"
According to the Mitchell manual the prefered backlash is 0.010"
Add 0.006" shims to each side for preload. As is suggested further down this thread, tap in one of the thicker shims, between two thick shims to keep from damaging a thin shim.
As a side note, I have always set backlash and tooth pattern together.
I'll be doing this (hopefully) tomorrow and will add a new post and/or correct this post. Other than I disagree with shimming to zero (how do you get zero w/out the chance of adding preload?), this makes the most sense in keeping with all the other types of differentials I have done.
*****End of edit