Setting Pinion Depth using MHD Method

Measuring the difference in head thickness is the easiest way to go when using FRPP gears. The Ford gears are usually extremely close, if not perfect when it comes to head thickness from gear set to gear set.

Don't be surprised if you end up using the old shims, or the exact same thickness in new ones. Alot of people have gooten away with just reusing the shims from the factory gears and not measuring anything, people even get away with swapping gears in multiple rear ends with out measuring or changing a thing.

I would still measure though, if anything it will give you peace of mind.

95GTAODE is correct but 4.415-4.4199 is the best starting point the overall thickness of shims and pinion depth will be determined when gear marking compound is applied and proper pattern is achieved...and if using factory gears you will usually achieve proper pattern if you install the same thickness of shims that were on the pinion installed from the factory...

there is a easy way to do this and it is to use the old pinion bearing if it is good or buy an extra one take it to a machine shop and have then machine the inside of the bearing so it will slide on and off pinion easily and use this bearing while achieving proper pattern with the gear marking compound do not use the crush sleeve until final marking and pattern has been achieved this will keep you from having to press bearing on and off constantly to add or subtract shims and when proper pattern is achieved press the new bearing on and recheck you should be right on it.then use the crush sleeve and install to proper in.lbs. which is different for new and used gears...






Checking the Pattern

Check the pattern for proper pinion depth only after setting the backlash. Brush three or four of the ring gear teeth with a moderate coat of gear marking compound in two different places on the ring gear. Rotate the ring gear past the pinion gear three or four times and then back so the pattern can be seen.

Pinion depth is indicated by the position of the pattern between the face and flank of the ring gear teeth. Backlash must be kept within specifications, and will therefore only slightly affect the pattern between the heel and toe of the ring gear teeth. Housing alignment and pinion bearing bore alignment can also affect the pattern from heel to toe and can not be corrected without machine work. In some cases an ideal heel to toe pattern can not be achieved. If the backlash is within specifications, you may disregard the heel to toe pattern. A contact pattern that is centered from face to flank always indicates correct pinion depth even if a pattern that is centered from heel to toe can not be obtained.

If the contact pattern is towards the face of the ring gear teeth then the pinion is too far away from the ring gear. Adjust the pinion shims to move the pinion gear towards the ring gear centerline (add shims; subtract shims for pinion support designs). If the contact pattern is towards the flank of the ring gear teeth then the pinion is too close to the ring gear. Adjust the pinion shims to move the pinion gear away from the ring gear centerline (subtract shims; add shims for pinion support designs).

When changing the pinion depth, make large changes (0.005" to 0.015") until the pattern is close. By making adjustments that move the pinion too far, you can determine that the correct pattern is somewhere between the two extremes. Then make smaller changes (0.002" to 0.004") until the pattern is centered between the face and the flank of the ring gear teeth.

When setting up a used ring & pinion, pay more attention to the pattern on the coast side of the ring gear teeth and pay less attention to the drive side. Low mileage gears should be patterned as if new.

the above was copied from http://www.louisvilleoffroad.com/Ring-and-Pinion-Installation-sp-9.html
which you have already read...


just some good info. here hope i have not confused you but when i installed my gears which were factory installed 3.73 gears off of an explorer i measured shims off old pinion removed and added new shims of same thickness and it patterned perfect and i have no gear whine at all...

what size shims usaully come in the stock gear set? I have 373s going in where a set of 308's came out, what size shim would you recommend starting with?

what size pinion shims did you use? I'm adding 373's to my car and would like to know where to start.

what size pinion shims did you use? I'm adding 373's to my car and would like to know where to start.