Stock 7.625 what's the average best 60' before it breaks
 

Thoses of you that run 7 5/8 rear end whats your gear rear end mods and best 60' .

I got lock right locker and richmond 4.10 .

Best 60': 1.88s

About 1.55 is where I started breaking them. Also the higher # gear you run the easier they are to break. I never broke a stock axel, always broke the pinion gear.

VIDEO CHIC

1.6197 60' 7.62 1/8th mile, front tires lifted off ground a little then $99 SLP diff retired. 4.10 gears, stock axles and housing were fine. Gear setup and welded tubes were fine. The worm drive assemblies in torsen diff siezed and broke teeth on one side.

Changed to 9" and 4.30 gears to make up for extra weight.

I was somewhere in the high 1.6 range and running somewhere in the 11's when I changed mine to a 9". I never broke it but it was also beefed up. As mentioned above, the weak link is the tiny ring and pinion. That will break before anything else. It depends on the shock load put on the gears.

I changed to a 9" the same time I installed a transbrake. I didn't think the 10 bolt could have taken more than one hit before breaking so I didn't want to take the chance.

1.69 is my best on an unprepped track on the stock 10 bolt.

You could try having it cryo-frozen to make it stronger and last longer, some dudes on the vette forum have had some luck with that.

Why don't you just run it until it breaks then buy a better diff.

Been pulling 1.5s for years now. - most of this year when not spinning pulling 1.51's-1.53s
3.73 gears torsion diff.

Re: Stock 7.625 what's the average best 60' before it breaks
 

Just got 1.73 out of it :nod: with a all internal stock l69 on 75hp shot ....

Re: Stock 7.625 what's the average best 60' before it breaks
 

i got about a 2.4 60ft before things started breaking.. lol shattered the spider gears on my first run ever!!!! :D

damn wheelhop..

been on a currie 9" and g-force t-5 ever since.. that hurt the bank.. $5700 for both

Re: Stock 7.625 what's the average best 60' before it breaks
 

i run a 3.42 gear and a torsen. best ever was 1.47. that was with th e 3.73 gear. now i run consistant 1.50 - 1.51

Re: Stock 7.625 what's the average best 60' before it breaks
 

I was doing 1.63-1.64 on drag radials when it broke. Bone stock with 3.73s.

Re: Stock 7.625 what's the average best 60' before it breaks
 

I broke the posi on the street, never got any times out of that yet. Weak stock posi unit FYI.

Re: Stock 7.625 what's the average best 60' before it breaks
 

hahaha that would be my inspiration at work.. lol its ok, i blew mine out before i hit the 60ft lights.. hence the 2.4 60ft i posted above..

edit: i just realized that my avatar IS my posi pieces.. lol

Re: Stock 7.625 what's the average best 60' before it breaks
 

you guys should post what tires you are using and whether you are using an aluminum girdel or not.

Re: Stock 7.625 what's the average best 60' before it breaks
 

26x10x15 hoosier drags. d06 i believe

Re: Stock 7.625 what's the average best 60' before it breaks
 

Yea, AL girdle, solid pinion spacer, welded tubes, zytanium cross pin, 275/60R15 BFG radial TA's. Gears are good and strong with that setup, axle shafts and **posi** unit are the weak part :(

Re: Stock 7.625 what's the average best 60' before it breaks
 

a solid pinion spacer and a set of lca rb's to get rid of wheelhop and an eaton posi to keep things going foward. no al girdle or aftermarket axles. been 1.678 with the old 3.73's and a 275/60/15 mt et street radial. have not been back with new 4.10's

Re: Stock 7.625 what's the average best 60' before it breaks
 

3.73's, 1000mile used posi(not sure what kind), stock axles, summit AL girdle, 245/45-17 KUMHO 711's!!! the crappiest tires i've ever been on.. skateboard tires could hook better.. but still destroyed the spiders.. lol

Re: Stock 7.625 what's the average best 60' before it breaks
 

M/T ET Drag 28x9x15 lock right locker stock 3.42 gear.Almost lift the tire off the ground :) at least on thr right side ...i think that on the left it got some air...but no one to tell :rolleyes:

http://img84.imageshack.us/img84/929...saisie2vi1.png

Re: Stock 7.625 what's the average best 60' before it breaks
 

60'....1.62
1/8th mile 7.31 @ 95.0 mph
1/4 mile 11.43 @ 118.2 mph

7.625" 10 bolt, GM stock 3.42 gear, powertrax lock rite locker, TA alum support cover, yukon axles, new wheel bearings and seals.

Broke 2 of those same rear ends in 2 weeks back to back..

1st one... I broke the pinion gear... Second one, I broke teeth off the ring gear.
----------
Forgot to mention that I'm running Nitto 555R 275/60-15 drag radials and lifting from wheels alittle at launch

Re: Stock 7.625 what's the average best 60' before it breaks
 

wheels spin/hop is a b!tch eh? you get it to hook and you'll actually save those parts in the middle. you'll start eating up pinion gears around the 1.6 mark.

Re: Stock 7.625 what's the average best 60' before it breaks
 

ya it is.. but no need to worry about anything now.. g-force t-5, currie 9" w/31 spline axles and spohn extreme duty DS.. just gotta upgrade to a crossmember mounted TA.. the trans mounted spohn one is killing me.. but i got the 3/4" heim and steel so its just waiting for me to start construction..

Re: Stock 7.625 what's the average best 60' before it breaks
 

When I first responded to this thread it was 8/30/04, still with same 10 bolt rear, same torsion diff and same gm 3.73 - only mod being moser street axles.
All of 2005/2006 continued with now low 1.4's 60ft times wit a best of 1.38 on spray, midway toward end of 2006 swapped in a T56..
Unfortunate car just got totalled - however the same rear is being transplanted into my new transplant vehicle 2004 firebird.

The 10 bolt is a weak link no doubt - figured I would run mine till it no longer could - well it out lived the car.. and may out live another..
Many years of racing as well as lots of street abuse, go figure..

Re: Stock 7.625 what's the average best 60' before it breaks
 

Thats interesting. Some take lots of abuse, some die on the street.

Re: Stock 7.625 what's the average best 60' before it breaks
 

My best is now a 1.52 60ft.
This is with lcarbs, welded axle tubes, stock axles, rear TA diff girdle, 3.73 gears and 28" et streets.

Oh, and a 100hp shot of nitrous.

Re: Stock 7.625 what's the average best 60' before it breaks
 

1.679
7.89 1/8th
12.38 1/4

all off of a footbrake

28x10.5S M/T's

welded tubes, 3.73's

Re: Stock 7.625 what's the average best 60' before it breaks
 

i have several 1.55-1.65 60 foots on this 10 bolt so far with the new 383 and probly 20 passes or so with the old L98 cutting 1.71-1.80 60 foots. This thing wont die and i'm happy about that

stock 2000 trans am 10 bolt with 3.42's.

Re: Stock 7.625 what's the average best 60' before it breaks
 

exactly my thoughts.

I'm going to add a TA cover, preload the caps, add mobil one syn with GM additive, and pray it doesnt expire

Re: Stock 7.625 what's the average best 60' before it breaks
 

The simple fact is that any car running 14’s or so or faster/roughly faster then 1.9 60’s will eventually break one if mess with it enough. Manual transmission cars with anything resembling aggressive shifting will break one faster, and throwing all the best parts will get you 2 or 3 more passes out of one, but you will still break it.

I’ve broken _every_ 10 bolt that I’ve owned at this point (a total of 7x now) in fast cars and slow cars, manual transmissions and automatics, all beefed up (solid spacer, TA cover, bearing cap hardware replaced with studs, welded axle tubes…) and stock. I’ve never had a car that wheel hopped on the launch.

I’m not sure that I can honestly say that any of the modifications/add ons _really_ make a difference in durability, if anything I would suggest that welding the axle tubes might help, even though that shouldn’t make any difference WRT to gear life (every one that I’ve broken has been gears), and maybe the solid crush sleeve/spacer. Conventional lube seems to help. I’ve had 2 blow up in less than 800 miles with synthetic (amsoil and redline shockproof) which showed a perfect pattern and weren’t making any noise. Lighter tires help… it seems really easy to break them with 17”wheels and sticky tires where the same tire on a much lighter 15” rim lasts much longer (and the combination weighs 12-14lbs less with the same height/width/type tire).

Re: Stock 7.625 what's the average best 60' before it breaks
 

One other thing that will keep it living longer is to put the car on a diet. If you can lessen the mass it has to move the longer it will live.

Re: Stock 7.625 what's the average best 60' before it breaks
 

[QUOTE=83 Crossfire TA;3877600] Conventional lube seems to help. QUOTE]

intresting, so what weight and brand did you use???

Re: Stock 7.625 what's the average best 60' before it breaks
 

It’s not really that surprising, if you buy an axle or gears from most of the big names (Moser, Strange…) they all come with instructions (or have at times) recommending against running synthetic in them.

I’m not sure that brand really matters . I hate to admit that I’ve had good luck with the cheap, almost generic stuff that I used to get at Hi-Gear automotive before the chain closed a few years ago. I think that you can still get the stuff at harbor freight and a few other places. My brother’s race car is running Castrol with no failures/issues (even though I generally don’t believe that Castrol even ranks on the scale of “good oil”) and I think that everything I own right now has either valvoline conventional or mobil 1 in it (I’ve never had an issue with it and I do believe that synthetic is worth MPG or a small amount of extra power even though it doesn’t protect the gears as well. I’m pretty sure that one of the manufacturer’s recommended “conventional Pensoil or similar” by name so I have some of that waiting to go in my 9”

breaks
 

From Richmond's install instructions:

"STEP 8. Fill the gear case with sufficient amount of RICHMOND GEAR 75-140 Synthetic Gear Lube with GL 6 rating, or better and maintain the proper level at all times." {emphasis added}

Auburn and Eaton say to use conventional gear lube with their posi carriers because they're too lazy to get with modern technology and develop/use friction materials compatible (for the application) with synthetics.

Synthetics have been blamed for everything from leaks to flat tires. Your gear breakage probably falls somewhere in there. I just broke the American gears in the 8.2" 10-bolt, not because I've used AMSOIL 75W-90 synthetic gear lube in it for the last 5 years, but because the stock factory open carrier (with PowerTrax) bearing support broke off the carrier.

Re: breaks
 

i cant remember what i got in my 10 bolt. supertech something but i dont know if its synthetic or not. Either way i'm impressed with how the 10 bolt is holding up

in about another week hopefully if all goes well, i'll be testing that rear with 150 more hp at the tire :) near 550whp has to break it but i hope it holds for a pass or two

Re: Stock 7.625 what's the average best 60' before it breaks
 

five7kid, to some extent I agree with you and in other places I’ve said that I’m not 100% sure that there is a correlation, that it could just be dumb luck, but I would also suggest that richomond’s recommendation might be weighted by them being one of the few (possibly only, but I haven’t checked lately) gear manufacturer that sells their own synthetic lube. Prior to them releasing that stuff they recommended against synthetic and I had a discussion at one point with their techs and they said it was because although synthetic does lubricate slightly better, it doesn’t stick/climb the gears like conventional does and conventional is better in extreme pressure situations at preventing metal to metal contact.

I just checked and Moser still specifically specifies non-synthetic in their instructions for their assemblies.

I can also tell you that one of the manufacturer’s would not be quoted saying this but specifically recommended Pensoil conventional by name.

Auburn and eaton (for that matter any clutch style posi manufacturer) will specify non-synthetic in high performance applications because the pressure/heat between the clutches causes synthetic to break down and it leaves different deposits then conventional does (I’ve heard it described as crystallizing) that damages the friction surfaces.

Re: Stock 7.625 what's the average best 60' before it breaks
 

Actually, here, it's on every page of the instructions that come with a moser 9"

That sounds completely backwards.

I would believe that it's because their frictions aren't compatible with synthetic, or that synthetic lubricates too well.

Re: Stock 7.625 what's the average best 60' before it breaks
 

Nope, I'm sure of it, and sythetic isn't more slippery then gear lube + friction modifier.

Synthetic is less likely to "break down" from heat than a petroleum based gear lube. The scenario doesn't make any sense. When I talked to the shop about it, they said Auburn can look at clutch packs of one of their units and tell if it has been using synthetic - but no mention of "crystallization" was made. I'd like to see documentation of that.

The friction modifier only effects the transition from static to dynamic friction between the plates to reduce chatter - and chatter is a non-detrimental condition mechanically.

I don't doubt that Auburn/Eaton posi's don't like synthetic gear lube - I have a bud who kept pulling his rear to get it reworked because the posi wouldn't last. Tried both Auburn and Eaton posi's, same results. I asked what gear lube he was using - Mobil 1, he said, why? Well, they don't want you to use synthetic with their units, that's why. Why not? he asked? I still don't have a good answer, and that was 6 years ago.

For the record, the new Auburn and 4.11 Richmond gears with Auburn posi additive and 75W-90 Valvoline petroleum gear lube are smooth as silk, and seemed to hold well during burn-out and on the starting line (just 6 runs so far). But, even with 1500' better DA than I've seen all summer, 60' and ET were still the same as the previous race when it still had 3.73's, PowerTrax, and 75W-90 AMSOIL synthetic gear lube, and slower than earlier in the year with similar air. That bugs me to no end.

This is far off-topic to the original question, but since you blamed synthetic gear lube for causing failure (and failure was the original topic), I thought it warranted a response.