Hello all. I just signed up for the forums and would like to post my experience with installing a set of FRPP 3.73's. The gears went into my '87 LX with over 150k on the odometer. I'm fortunate enough to have access to a auto shop with most of the tools needed to do this job including a press so that made things go a lot easier. Before I went for the install I printed instructions from this site :8.8 Axle Gear Install. I also researched the job thoroughly and studied the gear patterns. I set my pinion depth according to method #2 found under the "setting pinion depth" section on this site: Back to the Homepage when I ended up going with method #3 in the end to get a near perfect mesh pattern. To set pinion depth I measured the new and old pinions and found that the new Ford unit was .010 shorter than the factory one. The factory shim was .027 so I installed about .037 worth of shims behind the bearing to achieve the same pinion head to bearing length as stock. My wear pattern was the "high contact" pattern shown in the first link I posted. The instructions for that pattern are to add shims because the pinion is too far away from the ring gear. So I wasted tons of time adding shims and setting backlash as needed only to get the same pattern over and over. Finally I got frustrated and slapped it all together and took her for a spin. Needless to say I was quite dissapointed when I heard the ear piercing whine on deceleration. I parked the car for the night and went in again this morning for a redo. Finally I said "what the heck maybe following these instructions is messing me up" and for kicks I threw on the original pinion shim which gave me a pinion depth roughly .010 less than the factory gear and what do you know my gear pattern looked spot on! I adjusted the carrier shims to get the proper backlash and put it all back together. I was quite pleased when I drove the car and the gears are now whisper quiet just like stock. So in summary, I went against what the instructions said to do by subtracting pinion shims and got my target pattern. Maybe Ford manufactures the gears with the intention of using that factory shim?
Basically, I just wanted to relate my experience of having to go against instructions to get proper gear mesh. Now, of course a pinion depth tool is ideal for setting the depth but if you don't have one my advise is to start by using the factory shim behind the pinion head and check your pattern from there. Hope this info is useful! If anyone has any q's about the rest of the install I'll be happy to elaborate.
-Jake
P.S. the gears made a HUGE difference in acceleration. It's so much more fun to drive now.
Basically, I just wanted to relate my experience of having to go against instructions to get proper gear mesh. Now, of course a pinion depth tool is ideal for setting the depth but if you don't have one my advise is to start by using the factory shim behind the pinion head and check your pattern from there. Hope this info is useful! If anyone has any q's about the rest of the install I'll be happy to elaborate.
-Jake
P.S. the gears made a HUGE difference in acceleration. It's so much more fun to drive now.