12 bolt is hurting

Paul P · Posted: Fri Sep 14, 2018 10:44 am Post subject: 12 bolt is hurting

Hi All,
The other day I noticed a puddle of gear oil under the rearend of the Chevelle. Decided it had been 30 years since putting it together it might need some attention. Tear down revealed a few things some surprises and some expected issues.
Surprise #1
3 of the 8 C-Clip eliminator studs just fell off when I went to remove them. That was a surprise and a serious potential safety issue. I will replace them with ARP stainless pinion support studs so that will be sorted.

Surprise #2 The Moroso Brute Strength was a bit more damaged than I suspected. 1 of the pinions ate the cross shaft and the case. Sadly the case has .023" of wear at the pinion gear thrust washer spot so it is toast. So the spider gears are essentially junk. They no longer make the Brute Strength carrier which I think was discontinued in 2011. It was in a catalog from back then.

#3 expected issue was the gear set. It was worn nicely with an excellent pattern still but now it had .012" of backlash and should be replaced.

So what I have found as a solution is to replace the Richmond 4.10s with a new set and I found a great deal on an Auburn Gear ECTED MAX-Locker Differential. This should be not only stronger than the brute strength by design but will allow normal street driving when not locked.

I am also considering having the axle tubes welded. Not sure of what to do here. PM'd Adam because I know he has posted some stuff on doing this. There is a tech section on Mark Williams website that states using 308 filler rod for this. Going to talk to my welder on Saturday who does my aluminum welding for me to see what he thinks.

Site has been quiet are we all still out there or getting old and lazy?

Paul

Big Dave · Posted: Fri Sep 14, 2018 8:18 pm Post subject:

I'm Old and lazy but I check it twice a day.

Know you have committed to another 12 bolt but at your level of power I would be thinking that a Dana 60 would be in your future. It is a lot stronger than the 12 bolt due to three huge axle choices and the bigger ring gear. Your 12 bolt is the same as a Dana 44 by way of comparison.

Big Dave

Paul P · Posted: Fri Sep 14, 2018 11:06 pm Post subject:

Hi Dave,
It is setup with Moser c-clip eliminator 30 spline axles and a TA girdle to keep the caps from moving. It might have a bit more margin for power than it would otherwise. I do remember pulling the regular cover to install the TA girdle way long ago. With the 4.10s and diff installed the carrier shims had moved almost a 1/2" back due to the caps flexing! Shocked

Since the cover has been installed things have been kept in place for the most part.

af2 · Posted: Tue Sep 18, 2018 1:33 pm Post subject:

Hi Paul, Just saw this and PM'd you. Glad you caught it before it hit the fan.

Paul P · Posted: Tue Sep 18, 2018 2:53 pm Post subject:

Hi Adam,
Yeah wish I could share some pics. Damage was minimal but enough to make the cross shaft, carrier and spiders trash. New C-Clip eliminator retaining bolts will be installed too since 4 out of 8 studs that just fell apart upon removal. 3 on the passenger side and 1 on the drivers side.

Paul

Paul P · Posted: Tue Oct 16, 2018 2:02 pm Post subject:

So I am almost ready for powder coating the rear end. I have looked at the lower control arm mounts and they are not fully welded to the axle tubes is this something I should full circumference weld up before powder coating?

Big Dave · Posted: Wed Oct 17, 2018 10:11 am Post subject:

You obviously weld it up before powder coating. As to whether you need to, is the question. The lowers are in compression. They are being forced into the tube. The uppers are in tension. The cast Iron ears are strong enough as I have never broken them.

I have pulled the upper control arm mounting point off of the body on my '85 and had to rebuild the car body making the mounting point much stronger (no one makes a back half kit for an '85 Impala). I eventually built my own four link after welding in 2x6 rectangular tubing to mount the adjustable front plates.

Are you still using stock control arms? Or have you switched over to aftermarket rectangular tubing? The stronger lower arms prevent them from buckling under the force.

Big Dave

Paul P · Posted: Wed Oct 17, 2018 11:10 am Post subject:

Hi Dave,
I took a look at the lower stock welds and they were good. I use tubular control arms so they are ok. I also have the Hotchkis brace between the upper and lower mounting points to tie it all together. It is off to powder coating today. Thanks for the reply Dave.
Paul

10sec.et · Posted: Fri Oct 19, 2018 12:43 am Post subject:

Wow, Adam is posting again. Lol.

Ive been busy as hell myself. Keep trying to finish the race season but get to the track, get rained out, reschedule.... been going to tracks every weekend for the last two months. Shocked

I'm going to be the odd man out here but, I would just go with a 9". I know Dave aint gonna like that but, in my experience, makes life much easier.

Paul P · Posted: Fri Oct 19, 2018 10:16 am Post subject:

LOL 30 years of service on the 12 bolt I'm working on now so how much easier can you get?

af2 · Posted: Sun Oct 21, 2018 6:57 pm Post subject: