Suggestions Needed - 10-Bolt Build
 

Hey Everyone,

I spent some time looking through some of the threads and didn't find exactly what I needed. I'd appreciate some input for some of you who have done this a time or two.

I have some howling coming from the back of the car and and clunk when I put it in gear from time to time, so I'm going to replace the diff. I got a master mechanic who's gracious enough to help me put it in, but I wanted to pick the community's brain before we dive in so I've at least done my part.

I use my '01 WS6 M6 as a DD and it only has catback at this point. I have a new intake and throttle body, and will put some headers on, but I don't have plans to go much further than that. I took it to the strip once and plan to do a little auto-cross at some point too, but don't plan to do much more than that.

I've spent some time researching over the last couple weeks and wanted to air my thoughts out and see what feedback I could receive.

Because I want to DD and do just a small bit of screwing around on the track or otherwise, I think a 10-bolt will be fine, especially for my budget. I've seen post after post about Ford 9", 12-bolts, and so forth, but I don't need to spend $1,500 or $2,500.

From what I can tell, if I want a quiet ride, Motives and AAM are my best bet. Richmond is tough, but loud, and a lot of the cheaper options from like Summit Racing, Strange, US Gear, or otherwise have a better chance of being louder.

It sounds like my stock gear is a 3.42 ratio, which I'll be changing to 4.10 after reviewing this post to see how it would affect my ride: https://ls1tech.com/forums/gears-axl...ere-first.html

I've seen a lot of posts promoting Eaton carriers, and after reviewing Eaton's Application Guide, I'm leaning towards an Eaton TrueTrac carrier (7.5/7.625): http://www.eaton.com/ecm/idcplg?IdcS...Name=CT_128302
See page 5.

I've seen that I need to have enough carrier pre-load and that I use the right shims.

I'll also need an install kit, or to buy the equipment separate (bearings, gear oil, shims, etc.)

So I'd love some feedback on the above parts, which sounds like the minimum I need to consider when swapping my diff.

Also, I've been reading about how to strengthen the 10-bolt beyond this. I'm particularly interested in hearing about this as well...

http://www.hotrod.com/articles/hppp-...rearend-build/
This post talks about welding the axle tubes, using a different diff cover, and putting in a whole new set of axles.

http://www.ws6transam.org/10bolt.html
This post is for the 3rd gen, but it references the 10-bolt and mentions a Zytanium Cross Pin that kind of caught my attention. I was wondering if this was applicable for my build too. It also mentions an additional diff cover or girdle that the above post references as well.

I think that's it. Would love to hear back from anyone who has some experience playing around with a few different set-ups, or has been around this stuff for a while. I'm not looking to invest a ton of money, but I do want to do this well.

Thanks

Mike

It's really hit or miss with the 10 bolt. In my case I've been extremely lucky, and a lot of that has to do with how I drive it. I have 4.10's with a M6 and make about 600 rwhp on nitrous. Key things are no hard launches, avoid wheelhop, and no powershifting. This has worked for me so far knock on wood lol

The Truetrac is a good choice. Do not run gear oils with limited slip additive! Need for a aftermarket alloy pin is not necessary, Truetrac's don't use a traditional cross-pin.

U.S. Gear master rebuild kits come with Koyo bearings which are just as good as Timken, Also includes "super shims" for the carrier, add .005" to each side over the factory cast iron shim thickness. Has the wrong pinion seal!
Use OE GM seals.
Replace the wheel bearings with Torrington/Koyo brand only, GM/Spicer/Yukon are re-boxed Koyo's


I like Yukon Gears for corporate differentials. Easy set-up using the "nominal" pinion shims, Quiet operation, Quick break-in. Run some conventional 80w90 in it for 200-500 miles. Then run some synthetic 75w90.

Do not weld the axle tubes unless your willing to have the axle tubes checked for straightness & corrected as needed! You have a Torque Arm......Breaking the factory plug welds is less likely with this arrangement.

Welding the axle tubes is meant to keep them from shifting under power. A slight bit of flex allows the the ring and pinion to move away from each other thus having less surface contact. A lot of power being transmitted through a small contact area = boom. Bye bye ring teeth. It's a similar concept to diff cover/braces. The idea is to keep shit from moving and keep those gears connected. They are small and need all of the help they can get. it's not about breaking any factory welds.

Thanks for the tips, I appreciate it. What exactly is your setup for your rear? Is it just a standard 10 bolt, or did you modify it any way? And what brands?

Just a Trutrack upgrade but stock other than that. It seems they can take a decent amount of pre loaded stress, but not much in the way of sudden shock

Thank you for your recommendations.

Do you have any thoughts regarding the girdle that have been mentioned? It sounds like the diff housing itself can flex, which appears to be the purpose of the girdle.

Interesting theory, Let's say your right.....Welding on the axle tubes can cause them to "draw/warp" & they NEED to be checked & straightened if needed.

The only reason we started welding up the tubes back in the day was because of the plug welds breaking/shearing thus allowing the housing to rotate on the tubes destroying driveshafts & floorboards.

Your welcome. Cap support covers work as advertised.......DO NOT over torque the load bolts as it will distort the main caps!

I forgot something.......Install a Solid Pinion Spacer!!!

I have 8 years and about 15k miles on my Trutrac and AAM 3.73's. no problems at all (knock on wood). But I am an A4

Got it, roger that!

Good deal, thanks for the input!

If your axles have groves and are leaking around the seals, get new stock replacement axles, don't use axle saver bearings.

It's a fact jackson. I'm not saying anything about them being straight, nor am I refuting your plug weld comment. I'm saying that welding the tubes reduces flex and keeps the gears in contact. Think about what the tires are trying to do under a full throttle blast. They want to go forward and the axles tubes have to come along with them. Small axles with crappy welds are going to let that happen. And with those baby gears? Boom.

I'm thinking about straightness though. Because I have sheared the pin in my passenger right rear leaf spring on my truck with big ass heavy tires TWICE! The one that goes right through the middle and aligns them together Both times I put hundreds of miles on it before I could fix it. The axle tube would move around so much that that tire would be actually rubbing the wheel opening it had moved so much. Other side was perfectly fine, and nothing bad happened. Of course I didn't beat on it and my aftermarket gears and carrier probably helped, but the fact is that I put a s load of miles on a truck with the axle tube like 10 degrees off easy, and it didn't feel any different doing 70mph on the highway. So how straight do those tubes REALLY need to be? They don't need to be perfect is my thought. Drag racing with front wheels off the ground? Get em perfect.