I'm trying to setup my rear end right now, and I can't figure out how you are supposed to set the pinion depth and the preload...


Anyone know of a good online "How To" for setting up a 10 bolt rear end?

THanks,
CAle

 

If you don't have pinion depth measurement tools (such as the Kent-Moore parts shown in the FSM), then you set pinion depth by observing the gear pattern after the ring gear and carrier are re-installed. It can be a slow process.

Start off with the same pinion shim size that was used on the old gearset, and go from there. That should at least get you in the ballpark.

 

Eric is right.

 

Well...in my case it didn't even get me in the ballpark....I need somewhere between an 1/8 and a 1/4 " of movement to get it to mesh right....


where do I put spacers?

 

You should probably save yourself some money and a headache and find someone to set it up for you. Pinion depth is a precise specification and is crucial to proper operation. The spacer you are asking about should go under the pinion bearing, assuming you are working on a GM 10bolt. With no clue on what shim to use you are shooting in the dark. It can be anywhere from .019-.035" deep.

You set the pinion pre load by tightening the pinion nut, which compresses the crush sleeve. It takes about 450 ft pounds to crush the sleeve properly. The spec you are measuring is the rotational resistance of the pinion yoke, should be about 15 inch pounds with a new bearing. This also is a critical specification. Also make for certain you turn the yoke atleast 15-20 complete turns before taking the measurement, otherwise the rollers won't be lined up correctly and it will be too tight.

It's been awhile since I've had to do grunt work but I think my specs are pretty close, feel free to correct me if I'm wrong

 

Here is what you can do to measure pinion depth without a tool. You willl need a set of quality vernier calipers and a 6" piece of 1/2 x 1" aluminum barstock with a hole drilled in it (more on that in a second) and another flat surface (a marble window sill works in a pinch). If you don't know what vernier calipers are or how to use them I would suggest letting a pro handle this (it will end up saving you money in the long run). I would first suggest that you do not remove the pinion gear so you can measure the original pinion depth before you remove the pinion gear and swap them. Pinion depth is defined as the distance from the centerline of the ring gear to the back face of the pinion gear. With some ingenuity it is not that hard to obtain that measurement. When you remove the bearing caps the face that the bearing caps sit on is the ring gear centerline. You will take the barstock and lay it across the housing where the two caps bolt on. The hole will need to be drilled over the top of the pinion gear. The bar does not need to be drilled when resting in the rearend housing but you can at least get a better understanding of what is going on. Now place the barstock on the flat surface, turn the caliper on end and use the plunge rod on the vernier caliper and put it through the barstock. when fully extended it should be around .500 for a 1/2 piece of barstock. Write that number down. Now place the barstock back in the rearend housing. use the plunge rod and slide it all the way down on to the back of the pinion gear. take your reading. Subtract the thickness of the barstock (first measurement) from the total measurement, (second measurement) and voila you have your pinion depth. Now here is what you need when installing the new gears, if the new gears require a deviance from stock for pinion depth setting it will be stamped on the back of the ring gear. You may see a +6 or a -2, or you will see a number like -3.264 basically the long number is an actual number to shoot for and the small plus or minus numbers are deviance from standard. What you can do is measure the original pinion gear depth, check the gear for any measurement adjustments (all factory gears I have ever seen required no additional shimming or installed straight up.) and then adjust your pinion shim stack to reflect what your new pinion required. Always check the pattern with checking paste but every time I have done it this way it has been dead on or extremely close.NOw install the pinion and set the preload and then all you have left is backlash which is a piece of cake in comparison.

Cheers
Jason