Ford 8.8" ring and pinion setup question (w/ pics)

[Kevin Doe]

So I'm setting up the new gears in my 04 Cobra 8.8" housing. I've got the backlash set to 0.010". Checked the mesh pattern, and it shows that the pinion is too far away.

The stock 3.55 came with a 0.030" pinion bearin shim. I measured the head height of the 4.10 and compared that with the height of the 3.55. The 4.10 was 0.008" taller, so I reduced the pinion shim to an 0.020". Aparently that was teh wrong thing to do, so now I need to pull the bearing back off and put in a larger spacer, but how much larger? Go back to the 0.030", or somewhere between the two? I'd do ti guess and check, but I figure somene has experence on how much to change the shim based upon the gear patterns.

Here are some pics of the pattern.

Drive
http://i93.photobucket.com/albums/l55/Kevin_Doe/RX-7/0020drive2.jpg


Coast
http://i93.photobucket.com/albums/l55/Kevin_Doe/RX-7/0020coast2.jpg

[Black Horse]

I would put the .030" shim back in and check again. You will have to re-shim the ring to get your backlash. If you are planning on doing any track events where you'll be building up some heat in the rear I would open the lash to .012-.013".

Be careful with using paint to check your engagement, paint isn't a good lubrication and can actually cause wear. I like to use white lithium grease, it shows the pattern. (Check the engagement on both ring and pinion!)

[Kevin Doe]

Thanks Dave, I'll swap out the shim to the 0.030" one, and then reset the backlash to 0.012" and recheck the mesh pattern. Are you saying the paint will cause wear just rotating it by hand, or if I don't wipe it off before I run the gears?

[Kevin Doe]

Also have a question about carrier bearing preload. Right now I'm using as much shim as I can fit in w/o a spreader, and w/o forcing it. I plan on adding 0.006" shim on both sides to get the carrier bearings preloaded. Does that sound about right?

[Dirtyd0g]

Kevin I have a rotunda pinion depth gauge if you really want to know what shim to put in there. I have to go to my back doctor at 1 then I am heading over to reading. If you want to bring the stuff I will measure the shim for you.
Alan

[Black Horse]

Also have a question about carrier bearing preload. Right now I'm using as much shim as I can fit in w/o a spreader, and w/o forcing it. I plan on adding 0.006" shim on both sides to get the carrier bearings preloaded. Does that sound about right?

Sounds about right, I might keep a minimal preload with the IRS housing since it tends to heat up and hold the heat longer (no axle tubes to help dissapate the heat)

[Kevin Doe]

Kevin I have a rotunda pinion depth gauge if you really want to know what shim to put in there. I have to go to my back doctor at 1 then I am heading over to reading. If you want to bring the stuff I will measure the shim for you.
Alan

I won't be able to go home to grab all that stuff before we meet up.

[Kevin Doe]

Thanks for the Help Allen (not sure if I spelled that right).

[cobrajoe]

I'm pretty sure the pattern is supposed to be in the middle for the most part.