GM 12 Bolt Upgrade Q's
 

Hey, I'm NOOB when it comes to messing with rearends (cars ....) I would like to convert the GM Posi 3.55 12 bolt with a c-clip eliminator kit, anything else?

Can I use the same axles? IF I upgrade to larger spline axles then I need the posi unit also, right?

I would like to keep the 3.55's and if I could keep everything else that would be kool also .... cheaper too! I may participate in a auto-X or two but nothing like a circuit .... they are not here in NO Colorado, so street driven mainly!

Pro's and Cons with upgrading this 12 bolt?

Thanks for any advice ....

Michael

I've heard the c-clip eliminators eventually leak. I've been running c clips for as long as I've owned my car with no complaints. Only up grades have been the Eaton Posi and Moser axles.

I stayed with the C-clip set up and went with Moser axles also.

If you're going to run rear discs the C-clip Eliminator kits are an issue and as Gaetano mentioned I've also heard they tend to leak.

How much power and power are you running?

Thanks
 

That is good to hear .... did you upgrade to a larger spine axles w Moser? Hearing this I should be ok to run what I brung!


Another concern ... I already have Wilwood on the axles now and don't really what to change. I definitely don't what to mess with leaks either.

I have a warmed over SBC 331 .... maybe 400hp if I'm lucky!

Thanks for chiming in guys I appreciate the comments!

C-clip elliminator
 

I took an old Mark Williams C-clip kit off when I upgraded to the 9-inch Ford ends for the Baer brakes. The bearing has an O-ring around the O.D. and then uses an outside sealed bearing. To make it all work you need to gasket or seal the backing plate to the axle housing and then the bearing cup needs to gasket or seal to the other side of the backing plate. Mine did weep a little on the right side enough to contaminate my brakes shoes. But I don't see why this would leak any more than any other sealed bearing if you take care !

I tried to take mine apart without a press and ended up damaging them. I should have just saved the axles complete for a rainy day !

Moser axles...cheap click eliminator...upgraded posi and a rear gridle cover. Will take you into a 5-600 hp range safely. So do the mods and know that when you start adding power you may want make more mods to the rear end. Good luck

Thanks for the input guys .... I think I'll drive down to Mark Williams Inc. and take a tour and talk to the experts ... I only want to do this once!

We usually run the 7900 moser flush mounts and the large Ford bearing with the disc brake backing as an axle retainer.

Vince I see the advantage w the Ford BIG ends .... but I already have Wilwood 12.19 brakes installed w the chevy end, is there an adapter to retain the Wilwood to the Ford ends?

Thanks for the info .....

If you go with the c-clip eliminators and plan on a lot of street driving or auto-x, road racing etc, make sure you get their tappered bearing set up. I'd rather have the ends changed over to Ford..

http://www.competitionplus.com/index...t-application-

chevy bolt pattern :thankyou:

Honestly if you want to do that many upgrades you might be better off selling your factor 12 and buy a built Moser 12. That way you can do 33 spline, posi, new gears, axles and special hosing ends.

If you go this route, be sure to specify the 7900FM (flush mount) so your seal sits flush. That way you can use your brake backing plate as the retainer.

It really isn't that hard to put new ends on your axle housing. You already know the width that works so as long as the ends that Vince recommended will mount your brakes then you just need a long 1.25 inch bar and some adapters to hold everything straight. I don't know about you but narrowing the rearend was one of those bucket-list things for me. I am pretty happy I did it. I will loan you my adapters after I am done finish welding if you want to tackle it. The bar is just ground and polished shafting from the Inter-Web. The outer adapters have a 3.15" and a 2.84" shoulder. I think that covers the large Ford and the Chevy 12-bolt diameters. Here is a photo in-process.

http://i.imgur.com/lbKoMSkl.jpg

You probably need a pinion center finding tool also. I could loan you the one I bought from Moser. I is really well made.

http://i.imgur.com/nDoyBRfl.jpg

The pinion is 1/2 inch to the passenger side. All the axle companies are really good at answering questions if you get unsure about something.

I will get ahold of Moser and find out what I need for the Ford ends with tapered bearings and retainer that will accept my Wilwoods. I saw your update with the rear shot .... NICE!

Thanks for the offer, I will get back to you .....

Michael

if you have a Chevy bolt pattern brake set up the Moser 7900FM is the ends you will need. It features a Chevy bolt pattern flange and houses a large Ford Bearing.

http://www.moserengineering.com/smal...lip-axles.html

Vince .... thanks for the link, it should be Chevy ends but I'll check the upper and lower bolt measurements before I call Moser.

I appreciate the info from the guys that have done this before me ... Thanks.

A Miracle
 

does happen, I uncovered my 12 bolt from all the plastic bags I taped on it three years ago and whala .... I hit the jackpot w this 12 bolt I bought. The seller had it under his Firebird and said it was professionally rebuilt and never even had gear oil in it, he was correct.

Take a look ... I think I'm ready to go, gonna take off the perches and prep it for the Ride Tech air bar install, its on order now, I'm totally stoked (if you couldn't tell!).

http://imagizer.imageshack.us/v2/640...674/2B3OWC.jpg
http://imagizer.imageshack.us/v2/640...912/AWugvZ.jpg
http://imagizer.imageshack.us/v2/640...661/A1HAax.jpg
http://imagizer.imageshack.us/v2/640...540/1Qu0Jw.jpghttp://imagizer.imageshack.us/v2/640...908/9NX76M.jpg
http://imagizer.imageshack.us/v2/640...538/48SMFx.jpg

I do appreciate all the comments but, .... for the price I paid for this 12 bolt I'm keeping it fer sure, not sure what size spline the axles are.

She'll do fine under my Camaro.

Thanks for looking ....

Looks like it has an aftermarket ends already. They appear to to be Moser...at least they look like the Moser 12 bolt I have at the shop. see picture at post 11

Pop out the center shaft and see if it has c-clips.

What did you end up doing? I have a 12 bolt 1970 camaro rear with Mark Williams c-clip eliminators and drums. Wanting to run disk brakes bad but having trouble finding some other then the non popular TA 12 bolt disk brakes setup. Does anyone know if the s10 disk brake swap could work?

Depends on your budget.... You can hack the ends off and go to a full Floater set up with Corvette hubs and brakes

Hello,

This https://lateral-g.net/forums/showthread.php4?t=52854 will bolt directly onto your GM rear. This set-up will eliminate your current c-clip axles/c-clip eliminator kit and convert you into a full blown floater rear. You also would be able to run any brake kit made for C5/C6 Corvettes (both OEM and aftermarket). Not cheap, but is THE BEST solution for GM rears.

Jay

Hey I ended up selling the 12 bolt to a gentleman restoring a 69Z and I bought a Speedway Engineering 9" with Jay Miller's bolt on C6 ends.


It is the best solution and that's the route I took, thanks for answering all my dumb questions!!!!

Michael