I have found a reasonable price on the FMS M4209-H373 gear. I know of people that have this in thier Ls. Question is- What is needed for the swap? Is there any Special shims needed? In MM&FF they had JDM put in a set, but they are made by Precision Gear.They said it was straight forward. I just did not want to have the problem that people had with the 4.10 gears.( custom shims, etc.) Thanks Josh

 

TTT

 

Don't worry Josh, it is not that people don't know the answer to your question it is just that they don't like you! Just kidding. I wish I had an answer for you buddy, but I am don't. I am sure someone knows. Later.

 

With the Ford Motorsport Gears your stock shims should work, Dealer can install for you.

Jim

 

I need to do some thing to stay faster than you guys. I should be able to install myself just did not know about the shims, crush sleeve, etc. Thanks Josh

 

Josh,

I don't think anything special is needed for the 3.73's, but I would definitely get a new crush sleeve and maybe a shim kit on hand just in case to get it perfect since you're changing ratios. Otherwise, it could whine on you if the gear mesh isn't set up properly. BTW, I ruined 2 gearsets on a Chevy until I figured out the stock shims weren't close enough. But maybe the stock shims are close enough in the Fords since you're not doing a radical change.

Make sure you put the gear compound (Napa or wherever) on several of the ring teeth and set the parking brake just barely. Then take a 1/2" drive socket and turn the yoke forward and then backward thru the compound to see what the pattern looks like. You'll want the pattern to look kinda like a double-ended, round-nose bullet centered in the forward section of the ring teeth. If all looks well, put rear cover on and fill with oil.

Email me if you need help.

This link below is a different gearset, but it doesn't matter. The procedure is the same and will prevent a howling noise from the back end.

Jim

 

Josh,

Forgot to mention this in my prior post - if the backlash or pinion gear depth is wrong by even a couple of .001's, the pattern in the compound will look nothing like the link I posted. It'll be really obvious. It's also very important to have a micrometer for checking shim thickness and a dial indicator for backlash. If you don't already have these, I would suggest getting them. Tearing a rear-end apart is no fun when the screw-up is caused by guess work. And if you drive too far with it howling, it's ruined, trust me. Don't do like I did with my Chevy. I had $700 in gearsets (parts only) because I screwed up twice not realizing I should've measured the shims. Don't forget to look at my above attachment.

Jim

 

Chances are that your shim on the original pinion will be fine, there is about a 3 thousandths gap +/- before you'll hear some noise. Although the best way is to have the proper tools to measure it. I would how ever measure the backlash, and use a new inner pinion bearing. There are different preloads for new or used bearings on the pinion. If your not experienced with this get someone to give you a hand. Off hand guessing most pinion preloads are set up with a new bearing around 25/in lbs rotational. Your back lash should be around 12-15 again that's guessing off hand. If needed I can dig up the exact specs if your going to follow through with this. As far as marking the ring and checking it is a good thing, but your pinion depth should stay the same so the pattern should be rather close. I could probably pull up some stuff off of the pubs to help you out if needed. Email me at messer@htc.net if you need any other info ect.

Later,
Bill
2001 Silver Lightning

 

If you haven't done a gear set before, you may not want to try it..... it's a little tricky. As the other reply said... you can do alot of damage very easily. If you decide to try it, you'll need a variety of shims, a new crush sleeve, a dial indicator, marking compound, synthetic lube, and friction mofifier. If you've got any real miles on it, new bearings couldn't hurt.

The factory service manual will walk you through it.

 

I will have a very expierenced friend on hand, with the proper tools! Now I need to order that gear! Josh