symptoms of a breaking GM ten bolt rear end

**qwik219d9** · 07-25-2015, 06:07 AM

I've bought my rebuild kit and axel bearing w. seals.
7 625 7 5 8 GM Ring and Pinion Installation Bearing Master Kit 99 Up | eBay

Axle Wheel Bearing Seal Kit GM 7 5 8 2 8 5 12 Bolt Ford 8 8 5707 R1563 Auto | eBay

I'm finding there are differnt levels of gears some w/ much higher price tags.

Barnett is one of the oldest speed part shops they have been located in downtown
Atlanta for I think over a 100 years so they must be selling good stuff.
will this be a decent gear?
Motive Gear GM7 5 323 GM 7 5 10 Bolt 3 23 TN 3 Motive GEA | eBay

I want to show up w/ 2 quarts of diff. fuild 75/90 and whale sperm,
I ussalley change this fuild every 25K miles w/ Moblie one.synthetic

Should I show up w/ a cheaper none synthetic fuild like Walmarts Tech fuild.

Like is there a breakin period of like 500 miles for new gears?

should I expect him to provide
locktight
preamatex for gasket
none hardening sealant ?when none hardening sealant is used will the pinion seal
never seap oil?

I'll show up w/ hotel towels and someone mentioned blue paper towel,5 cans brake
cleaner.

hopefully this rebuild will last about how many miles?

and when it doe's break again hopefully someone will have designed a braket that
bolts to a 8.8 for a torque arm mount I think someone has made one for his car.
Thanks

**RONS98TA** · 07-25-2015, 07:42 AM

I had a similar situation when I was supervising a new set of mechanics at a dealership. New guy, still in high school, was told to change the oil in a car. So he drained the oil. Replaced the filter. Then added oil with one of the oil fill hoses that come off of the ceiling......until it overflowed out of the valve cover!!!!!! Thank GOD I walked over there just as it started to spill out and before he tried to start the car. OMG, I never knew just how much oil the entire engine would hold.

***SMWS6TA*** · 07-25-2015, 11:06 AM

Originally Posted by qwik219d9

I've bought my rebuild kit and axel bearing w. seals.
7 625 7 5 8 GM Ring and Pinion Installation Bearing Master Kit 99 Up | eBay

Axle Wheel Bearing Seal Kit GM 7 5 8 2 8 5 12 Bolt Ford 8 8 5707 R1563 Auto | eBay

I'm finding there are differnt levels of gears some w/ much higher price tags.

Barnett is one of the oldest speed part shops they have been located in downtown
Atlanta for I think over a 100 years so they must be selling good stuff.
will this be a decent gear?
Motive Gear GM7 5 323 GM 7 5 10 Bolt 3 23 TN 3 Motive GEA | eBay

I want to show up w/ 2 quarts of diff. fuild 75/90 and whale sperm,
I ussalley change this fuild every 25K miles w/ Moblie one.synthetic

Should I show up w/ a cheaper none synthetic fuild like Walmarts Tech fuild.

Like is there a breakin period of like 500 miles for new gears?

should I expect him to provide
locktight
preamatex for gasket
none hardening sealant ?when none hardening sealant is used will the pinion seal
never seap oil?

I'll show up w/ hotel towels and someone mentioned blue paper towel,5 cans brake
cleaner.

hopefully this rebuild will last about how many miles?

and when it doe's break again hopefully someone will have designed a braket that
bolts to a 8.8 for a torque arm mount I think someone has made one for his car.
Thanks

Look at my 8.8 thread you'll see how it's done.

**qwik219d9** · 07-26-2015, 07:42 AM

I'm still waiting for a response to this Motive gear like is this a decent gear I need to place my order?

Motive Gear GM7 5 323 GM 7 5 10 Bolt 3 23 TN 3 Motive GEA | eBay

Scott what you have done is way more than my skill level

I'm on the lookout for a junk yard ford truck 3rd member then get a 9" w/ axels w/ TA mount.

I'm curious about power lose w/ a larger ring gear?

***SMWS6TA*** · 07-27-2015, 07:03 AM

I've read some where for 12 bolt/8.8's is around 15-18% loss and with 9" it's around 20-25%. Tire size also effects this too.

**Firebirdjones** · 07-27-2015, 07:34 AM

There is some power loss with a 12 bolt or 8.8 but the difference between that and the 7.5 is so marginal you'll never know it.

Even if you were worried about saving 4-5 HP with that 7.5 incher, it doesn't do much good if it keeps breaking all the time.

9" takes a little more power to turn because of the pinion gear relationship to the ring gear, it's placed lower from centerline. That's what makes the 9" a bit stronger, not that the ring gear is only slightly larger (9" vs 8.875") Because of this pinion gear/ring gear relationship it's a bit harder to turn a 9". Not really a concern in my eyes though. If you're a racer, or even just spirited driving, reliability comes first.

The fact that GM even put a 7.5" behind a car with over 300hp and a manual trans just shows how cheap they have gotten over the years. Should have never been offered to the public.
Without being specific, In the 60's, 275HP and manual trans automatically triggered a 12 bolt rear in the Chevrolet lineup. GM realized they had an issue with that in 1965. Guess these new suit and tie pencil pushers are too young to remember that.

**qwik219d9** · 07-27-2015, 08:28 AM

I'm still waiting for a response to this Motive gear like is this a decent gear I need to place my order?

Motive Gear GM7 5 323 GM 7 5 10 Bolt 3 23 TN 3 Motive GEA | eBay

**Firebirdjones** · 07-27-2015, 10:07 AM

I gave my opinion of Motive back on post 53. It's "okay" but not what I consider the best out there. For what you are doing, sticking it in a 7.5" rear, it's not going to matter much.

What's more critical in the 7.5" rear is to keep the gear ratio very mild, 3.23 or 3.42, 3.73 is pushing it. Once you get up into the 4.10 range you only have 1 and 1/2 tooth contact on the pinion in relation to the ring gear because the diameter of the ring gear is so small (7.5") and a 4.10 ratio has a very small diameter pinion. This creates a weak link in the rear, as if it didn't have other areas to worry about already. It's the biggest reason why you see teeth shaved off the pinion all the time.

With a 3.23/3.42 ratio you'll have 2 1/2 to 3 teeth contacting at any given time....much stronger.

**qwik219d9** · 07-28-2015, 03:12 AM

Thanks FBJs and all others diffenitly learned a lot about REs

hope to have the TA on the road this weekend will update.

**Firebirdjones** · 07-28-2015, 04:36 AM

I'm sure it will turn out just fine.

**qwik219d9** · 08-10-2015, 06:27 AM

rear end rebuilt w/ used gears absolutely no noise
While coasting (can't hear much w/ TTS LTs/custom Y w/ flowmaster merge and hooker cat back cars not loud under 2K RPM) and going slow in reverse.

Delivered the car on Saturday at 5:30PM first time car was ever on a tow truck. the man had a actualle shop in his 20 acre backyard.
I wasn’t expecting the man and his assistant to do as much as he did, he actualley planned to get started and finish Sunday morning.
While I was there I got to observe wheels and axels removed, axel bearings beat out, housing cleaned w/ the brake cleaner and then w/ shop air sparying the mineral spirits (used one can of brake cleaner and approximently
25% of a ½ gallon of MS which I supplied) the assistant cleaned it very well.
(I was a little concerned when I observed brake cleaner mist coming out of the houseing getting on an riuing the paint?)

Then axel bearing beat in the man said they and all bearings could have been reused he did use the new stuff.

The axels where smoothed w/ a stripe of low grite sandpaper where they contact the race.

Then he attached his device to houseing where the carrier would normalley be, someone borrowed his depth guage
So he asked me to stay w/ his 20 year son (not sure who was watching who) while he got the guage he said he wanted to mearsure the pinion dept. while it was fresh on his mind then stop, it was about 9:30PM then I was there as a extra set of hands and did contribute just a little.
I left at 9:45PM

The man actualley finished the job at 11:30PM ( he test drove 5 miles I asked him how it ran he said very stronge and w/ out me asking he said I did’nt get on it which is a dead give away that Ok for 5 miles) that’s a long day and week, work full time at a dealership then all night when I got there Sunday at the requested 9:00am
He was hard at fixing cars had a bunch lined up, (the whole time I was there, folks just kept rolling in the man was telling each of his sons what to do as he overseed)) when I told the tow truck Guy the address he knew exactly where we were going, like I said earlier I allready heard about this man just never had to have any repairs.
other comments
1.the man used grease on the paper girdle cover didn’t use the prematext I bought.
2.I asked if he poured both quarts of 75/90LB gear oil in he said yes, whenever I change the diff fuild I usalley use 1 ½ quarts ½ left over.
3.asked if he used only half of the whale sperm Posie additive ( I think it only needs 3 OZ) he said he used the whole tube.
Then he told me I don’t need this additive because my carrier was a spider gear type, explained both wheels are allways locked together however it is a LSD (I’ll read up on this), it’s not like other carriers that have rebuildable cluch packs.
4.I did’nt see a parts cleaning machice and did’nt observe the carrier being cleaned (I did’nt see everything) I sure hope
It was clean the assitant said he cleaned it I think w/ shop air.
5. I asked and he said I could have drove the car over, if you broke another tooth off the pinion we would still have to clean it.
I was more concerned w/ another tooth breaking and eating up the carrier, plus wasteing $20. of gear oil better to tow as FBJ suggested.

Anyway I’m very Happy to have the TA back.

Other stuff the man was kind enough to do (that I didn’t even ask for to be done)

When I arrived on Sunday morning he came up to the Van to greet me and I assume he felt no cool air from inside the Van so he asked if the AC was working ( I have actualley been trying to adding 123a freeon and showed him my little guage that came w/ the freeon)

He say’s I’ll check it pulls out his real AC guages inserts die oil into sys. Finds a high preasure valve leaking a $4. part, connects a device to suck the moisture and freeon out of sys. askes me to cruise to store try car out, buy the freeonn and now the Van is cool air.

Then he did the same AC procedure for the car cool air once again.

He also cured the GM bump my Van thread discussed here http://www.ls1.com/forums/f8/excessi...-tools-180928/ had he knew exactly what the bump was when I described it dirty splines on the driveshaft exact same advice as FBJ offered he used a pink chevron airaplane grease
Applied w/ tooth brush.

I felt very comfortable w/ this man first time I never asked how much extra would this cost for AC and bump on Van.
When I asked how much do I owe you and you did alot more than was initialley agreed upon he said he ualley charges $30. for AC service he did’nt even mention the Van. He did the AC and van for free I added a tip for him saying let me at least buy you and you’r sons lunch.

When I paid I added another $20. tip for the assistant that pointed out my exhaust not being secure at the over the axel tube (that U clamp has been beating on the heat shield for years making a very embrassing rattle that I could never find lying on my driveway) plan to have the muffler man tack it there.
Glad I finalley got to meet this excellent mechanic and very nice man.

?if these gears where gonna make noise they would have done so right away correct? I have only driven 20 miles.

I’ll post again w/ price list for others that want to rebuild.
Thanks

**RONS98TA** · 08-10-2015, 06:37 AM

Sounds like the man was actually "the man". LOL. Glad it all worked out for ya. Good to see there are still hard working honest mechanics out there like myself, that just wanna get things fixed for a fair price, instead of cheating and lieing to people just to make a quick buck.

**qwik219d9** · 08-10-2015, 06:54 AM

Originally Posted by RONS98TA

Sounds like the man was actually "the man". LOL. Glad it all worked out for ya. Good to see there are still hard working honest mechanics out there like myself, that just wanna get things fixed for a fair price, instead of cheating and lieing to people just to make a quick buck.

Ron you got that right he fixes rear ends at the dealership all day long. just before I left I asked him about are Toyota Rav4 and explained about where it had been repaired in the past and them taking gross advantage of labor and parts he explained he isn't trying to rip off anyone WOW that's a understatement.

I just posted a long update there are a few ?s that I would like the LS1 folks to clairafiy.
this is the main one
?if these gears where gonna make noise they would have done so right away correct? I have only driven 20 miles.
Thanks

**Firebirdjones** · 08-10-2015, 07:27 AM

Sounds like you found a good mechanic to stick with.

Yes normally if gears are going to make noise they'll do it within the first couple miles. After 20 if still quiet then you will probably be okay.

**qwik219d9** · 08-10-2015, 07:40 AM

Originally Posted by Firebirdjones

Sounds like you found a good mechanic to stick with.

Yes normally if gears are going to make noise they'll do it within the first couple miles. After 20 if still quiet then you will probably be okay.

excellent

1.what about the brake cleaner mist I observed contacting the 1/4 panel will it damage paint or clear coat?

2.I feel like a complete fool adding this whale sperm Posie additive whenever I change diff. fuild was the Man correct my carrier doesn't need this additive?

Thanks

***SMWS6TA*** · 08-10-2015, 07:53 AM

He would be my only mechanic from now on.

**Firebirdjones** · 08-10-2015, 11:48 AM

You probably have the torsen diff, no additive needed with it, but if you did add it, it doesn't hurt anything.

Brake clean generally doesn't hurt the paint, depending on it's strength, and in small doses. I use a non chlorinated formula here, it's mild brake clean. I can spray it directly on painted parts and it takes quite a long time of constant contact and some rubbing with a towel before you can see it start to remove paint. It's not like lacquer thinner or anything like that, but at the same time something to be cautious of. Some chlorinated formulas are pretty strong though.

A fine mist?? I wouldn't worry about it. Wash the car and give it a good wax job

***SMWS6TA*** · 08-10-2015, 12:42 PM

Its brake fluid you don't want to let sit.......

**Firebirdjones** · 03-23-2016, 12:22 PM

Yep that bolt breaks usually when the case is worn and putting side load on that pin/bolt, and it snaps. You'd never know it until it comes time to remove the C-clips to pull axles, then you have that Oh Shit moment.

Usually they break just past the ends of the threads and it leaves 3" or so if pin up inside the case. There is no real easy way to fish that out, usually they are frozen in there. Any time that has happened to me I've had to carefully grind and cut it out, very time consuming. May not be worth your time.

If you were close I'd sell you my 10 bolt with 3.42's out of my wifes 4th gen with 80k on it. Works perfectly. But if you found one for $75, snag it, I certainly wouldn't sell mine that cheap.

**Mecinoid** · 09-17-2016, 04:05 AM

Stupid me.... I just made a similar mistake. I do not know what I was thinking. I filled my rear end up with Royal Purple to the fill hole in the rear end cover. (Moser with girdle type.) It has been a few years since I have done this service and so when I was checking the oil level, I was checking it by the rear fill hole forgetting this little issue of the factory fill hole. So, I just now let out 1qt of oil from the front fill hole. Only drove about 20 miles so far so no oil blew out the breather. Thank you guys for reminding me of that little difference.