Honestly, as far as I can tell, it looks like we have an unfortunate assembly error. I only have a bit over 2500 miles on the 12 bolt rear end. I haven't even came close to testing the limits of the 12 bolt. I've been struggling with a valve train issue, timing, tuning issue, and rarely get to even get down on the car. After four years, I never even made it to the track. It broke while I was just driving it la de dah to work and home. As I was leaving an intersection, I heard and felt a loud clunking shake. 100yds later I was stopped at the next stop light wondering what the heck(?). I pulled away with all the other rush hour cars and bam clunk no more forward motion. I luckily coasted into a low use turn lane and poked around wondering if my transmission, or diff broke. I ended up getting flat bed towed home. I put the vette up on the hoist, and isolated the problem to the rearend. I dropped it out, and as far as I can tell, it looks like the ring gear bolts backed off and chewed up the cover, and bearing cap. Thankfully, there was absolutely no way this broke from abuse, just an assembly mishap.

It was built by Mike (Tracdogg2) one of our forums two "reputable" 12 bolt builders. I had a lot of issues working with him when I had him set up my diff, control arms, and half shafts, so I didn't do a all praise the great Mike write up on the forum. I've been ghosted, just like when he told me 3weeks to build, all parts available, and it took nearly 3 months to receive my diff, half shafts, and control arms. It wasn't until I scheduled a flight to texas, and asked him to pack it all up and send it to Gary that he finally started to work on my parts. I'm fine within reasonable delays. Just keep informed and have a legitimate excuse. I felt that once he has your money and parts he'll get to it when he feels like it. No updates, or explanations for delay. Your results may vary. Good luck.

I sent Mike pictures of the assembly mishap asking his thoughts, and what he could do to help me get back on the road, and never got a response.

Clearly the ring gear bolts backed off and destroyed the rear end. The ring gear wasn't pressed on. Ring gear bolts weren't hardened, or chamfered, Potentially not torqued, or maybe the bolts bottomed out, or maybe no Loctite, ring gear shifting around could have caused the bolts to loosen, I don't know, but at least it didn't break do to abuse, Honestly, I work in manufacturing, things go wrong sometimes do to distractions, or missing a critical detail. I didn't ask for money back, just help getting it repaired.

I reached out to Gary. He was beyond helpful, taking time to respond to emails phone calls, and estimating costs to repair, and give an honest timeline. I really wanted to drive my car this year, and Gary was pretty busy, so I reached out to Detroit Speed to ask about their hammerhead diff. Skip at Detroit Speed had me contact Fuzzy at GearFX driveline to see if he could rebuild my diff. 3 weeks later, I had my diff back! Great guys who went out of their way to help me out.

I'm disappointed in Mike, but I know others can't say enough good about him. Clearly, he can do good work, and provide customer satisfaction. It just didn't work out for me.










I attached pictures.

 

Wow-that's a mess.

 

Yep, it was a mess inside, but I was surprised how good the gears looked despite all the metal particles inside the housing. Unfortunately nothing was reusable except the case. I was real happy with GearFXs willingness to help me get it back together. GearFX assembles the new Hammerhead differentials for Detroit Speed. They are someone to consider if you need a heavy duty C3 diff. 33 and 35 spline options instead of 30 like I have, plus you could go with a truetrac instead of a posi unit. Plus they offer more gear options! Thanks for looking.

The biggest bummer now is that I broke my wrist and can't put it back together. Although, I have a friend that may be able to help me put it back in next weekend. Driving with a cast may be difficult.

 

Sorry for your loss , I have one of Gary,s finest 12 here and a friend has one of Mike,s "super" 10,s . He just got his vette on the road and his sc 383 is very capable of taxing his drive train . So we will have our own little comparison going on here .

Glad (but not surprised ) to see Gary was helpful as possible.
Thanks for posting your problem , btw did you receive any run in procedures for the original diff

 

So the point of this post was to what?? Bash Mike? Or praise GearFx or what?

**** happens with custom built stuff, parts fail from oem defects and other factors besides just assembly error. I’m quite sure Mike would have stood behind and repaired your diff. Granted he is usually pretty backed up with work and his timeline is usually a month out.

I SERIOUSLY doubt that Mike did not locktite/torque the ring gear bolts. I watched him build my diff and “run it” on his diff dyno, monitoring housing/bearing temp during break in, that dude is very meticulous.

Sucks you had a problem but...I’m sure Mike would have fixed it.

Good luck with your new diff.

 

Back in '98/99 I had the ring gear bolts work loose in my '84 Z28. Heard and felt a 'clunk' leaving the parking lot at work, it seemed 'ok'. By the time I got near home it felt like something was 'catching' in back. Dropped it in neutral and coasted into a repair shop.

 

AJ, Several points are being made. I am "bashing" Mike some because my first experience was horrible, he flat out lied to me on the timeline for my build just so I wouldn't use Gary. Mike was very enjoyable to talk to about my build, knowledgeable, etc. He/we confirmed that all parts were available, he was available, but his promised 3 weeks turned into 3 months, and he ghosted me for 2 months. Not very professional. I was still happy that he provided the service, but felt taken advantage of, and he never spoke to me or emailed me. He had Debbie do the dirty work, emailing, calling and explaining.

AJ, I politely reached out to him for assistance to fix my current mess, giving him the opportunity to redeem himself. I didn't say he did a poor job, I didn't ask for a free repair, or point blame at his quality. I just asked for help, advice, and his thoughts (twice). He never responded. I reached out to Gary, because I knew he would respond, and try to help. I reached out to Detroit Speed because I was curious if I could just buy their Hammerhead differential. They are on back order, but thought they could help. I want the forum to know there are new options for heavy duty IRS's. All bolt in no custom grinding, machining, or special parts. Very cool!

AJ, I completely agree, and tried to point out that I understand things go wrong, and stuff breaks that shouldn't. I've been building and modifying cars since 1982. I've had my fair share of failures. Thanks, I hope my new diff works well and holds itself together.

Bazza77, I did the typical break in, 5 short drive heat cycles, figure eights, and letting it completely cool. Then about 10 short 20 - 30 mile short stop and go short highway drives. Drove it sanely for 500 miles changed gear lube, additive. No issues, quiet, no whine, or signs of issues.

 

That's very sad and I would wish that TD would rectify the situation.

I picked up a spare rear end in 2018 to put my 4.11 gears in. The donor vette had some bubba action going on to make it a hot rod. One failure was who ever did the rear end. The ring bolts were all loose and some half way out. Just a failure waiting to happen

 

Did you miss the part when OP says that he actually didn't?
Thanks for telling us your fellings are more important than his facts.

 

I'm glad that were getting some posts where ring gear bolts backed out, were loose, etc. It's comforting know it happens. I feel like Rodney Dangerfield...If it wasn't' for bad luck, I wouldn't have any.

 

I have heard of this happening before as well. Also heard of using incorrect ring gear bolts/washers etc... Im sure anything is possible. Looking at your pics, it definitely looks like the bolts backed out and caused the initial issue. WHY they backed out is the question.

At least you’re back in business, unfortunately on your own dime. Hopefully Mike will make it right. I won’t make excuses for him because I don’t know the situation but, I know he was working multiple jobs there for a while, and in the midst of moving, so maybe he got off track in the shuffle.

He’s a good guy though. I tore up a ring gear in my diff, Mike had me bring it to him, and he rebuilt the entire thing on one day, while I watched him, he ate all of the parts, labor, everything...I was literally in and out the same day. I’ve had that rebuilt diff in for 9 years now and 27k HARD miles... I had great service from Mike. I eventually had him do all of my dads 66’ verts front and rear suspension/diff and that car has been fine as well.

And you can never go wrong with advice from Gary Ramadei....dude is a genius on this stuff.

 

Mike Dyer is currently building a super HD 10 bolt for my 73, including outer axles, half shafts and assembling the trailing arms.
I could not be happier with the service he has given me.
He has taken longer than he originally quoted me, but I told him up front that I am in no hurry and that my project was a couple years from completion, so he could work on it when he had the time and certainly no rush.
Mike told me he was back logged because the roof on his shop was partially lifted off and he suffered flood damage in the shop from this past winter storms.
Until he was able to get a new roof put on his shop and mop out the water and mud he was unable to machine parts or do assembly.
I have called Mike a couple of times to ask technical questions regarding my build and he has been extremely helpful and when I left him voice mails, he has returned my calls.
Mike called me last week and told me he has been back to full production, is currently assembling my differential and will be receiving the outer axles and half shafts from Tom's this week, then he will begin setting up my trailing arms.
At this point I couldn't be happier with the service I have received from Mike.

OP, I am sorry that you had a failure with your rear differential.
I'm glad that you posted the possible cause and that others have chimed in with similar experiences.
Hopefully the information you provided to those, like Gary and Mike, who do excellent custom machining and assembly of our differentials, will cause them to look at these areas more carefully during assembly.
Good luck with your new diff.

 

To OP. Sorry to hear about your diff failure.
But not surprised.

When I had Gary build my Super 10, I documented every step here on the forum with pictures so everyone could see how its supposed to be done.
An important detail missed by many is the use of ring gear bolts with lock washers. vs ARP ring bolts with loctite.
This issue is not the first time with cheap lock washers being used instead of ARP bolts.
If you want to see the difference, check out my thread here
https://www.corvetteforum.com/forums...ial-build.html
Look at post #14 to see how Gary machines the case for the ARP bolts.
Gary is a true craftsman when it comes to building our differentials.
He is working on another one for me.
He does not take more work than he can handle and always communicates with you. I had almost 200 pics of this build. Plus he called me at night often to discuss progress and the build in general.
Unlike the guy talked about here.
I have a friend who had a 12 bolt built by Mike and it took a YEAR and a Half to finally get it. There were issues with the Ridetech TAs matching up to the half shafts. But the communication was horrible.
Plus you will never see multiple pics of the inside as it is being built.
One guy on here claimed to have one of his Super 10's and the one inside pic he posted showed that the posi was not even tuned properly. And it still had the spring pack inside.
So.....you can go cheap and get no support or you can buy quality from a stand up guy.

That's all I have to say.

 

Well there you go AJ. Clearly you and Oldcarbum are pro Mike as you should be based on your experience. Learning from our mistakes, owning them, and making thing right go a long way towards building customer satisfaction, and building loyalty. I'm happy things worked out and are both satisfied.
bmans_vette I took a look at the post. One of my concerns was no relief for the radius on the ring gear bolts to washer fitment. They would torque, but not seat on the intended mating surfaces. The bolts and washers were to trashed to determine if it may have been the probable cause.

 

Bmans vette "Quote"I have a friend who had a 12 bolt built by Mike and it took a YEAR and a Half to finally get it. There were issues with the Ridetech TAs matching up to the half shafts. But the communication was horrible" Quote".

Bmans vette,
My question to you is, your friend who had Mike build his 12 bolt, has it failed or given him any problems?

 

And thanks for your smart *** reply.

 

You're welcome, shill.

 

Hi.
To answer your question about that 12 bolt build.
The rear and TAs are finally in the car and the body is being painted. So no road time yet. This guy is in GA only 6 months of the year. So each delay ended up pushing it back a year.
He might see this thread and comment. As far as I know he is pleased with the result just not with the service. I will not speak for him.

 

Thanks for the response!

Several months ago I did extensive research to find someone to build the differential for my 73.
Both Mike and Gary were highly recommended and I could not find any negative comments or threads regarding poor work, or customer service.
I do have somewhat of a budget to build my car so cost was part of my decision to ask Mike to build the differential.
Mike was a little cheaper but not by much for like for like work.
As I stated earlier, so far I am pleased with the service I have received and hope the differential gives me years of good service.
Greg

 

There's no question that Mike does great work based on others feedback, but this does seem unusual. They look like they might be ARP bolts (12 point heads) but if so then why the lock washers? Does seem strange. I did the ARP bolts with loctite and countersunk the holes to clear the chamfer when I built mine. ARPs always (at least from what I've seen) specify not using other washers under the heads.