8 3/4 stocker rear
 

well looking to the 2011 season fresh motor ready to dyno ,i pulled the center section to check the ring and pinion and found some fractures on the ring gear along with razor sharp edges on the pinion, there are seveal reasons why this happened and i can list them but want hear from the racers who run a 8 3/4 and what they have run into running this rear thanks gmonde

Re: 8 3/4 stocker rear
 

Razor sharp pinion? How about a picture of that please. How does the pattern look? How many passes does these gears have on them? What ratio are you running?

Re: 8 3/4 stocker rear
 

Lots of variables to consider but highly recommend you first call Jim Bailey. Here's his website:

http://www.finishedracing.com/

Re: 8 3/4 stocker rear
 

Possably improper set up? Or the thinner weight gear lubes some have been running? Ive set up several 8 3/4 rears in the past and all of them are still together and in good shape today. One was run in an 3730 lb IHRA K/CM MoPar with a 360 crate motor running 11.30's, hi stahl converter and its still good to go after 10 years and lots of runs. These were 4:88's. Im NOT saying Im that good....maybe just lucky? Maybe just the wrong heat treat of the gear set? You should have it rockwell tested if you can to see how hard or soft it is. Just because its new or a major manufacturer dosent mean its always right. I found that GM (Pontiac) screwed up a bunch of new Super Duty 455 rods many years ago and they were to hard from improper heat treating causing breakage. Pontiac recalled them when they rechecked them themselves. Just trying to give you some ideas here.

Re: 8 3/4 stocker rear
 

Richmond Gears? I have cracked and broken the teeth of a few sets over the years. I think they are to hard and brittle. I have an old set of Zoom gears that have lasted forever.

Check the pinion depth, that could be some of the problem.

I have always run the 742 case with 1 3/4 straight pinion, some have trouble with the 489 case tapered pinions, they want to push back under load and crack the caps.

With the weight you are carrying you are close to the limits of this rear without some upgrades.

I have only heard good things about Jim Bailey's treatment, my next set of gears will be done. Can only help your situation.

George

Re: 8 3/4 stocker rear
 

x tech good answer on two of the counts,,,,,, yes 4:88 and i switched to a synthetic 75/90 half way thru last years season and to add i lost traction on two runs witched caused the car to shake real bad ,,as far as set up these where a set of used gears that i set up and worked to get get the best gear pattern leaning towards the toe of ring gear ,if you look you can see that the drive on the ring gear runs the entire tooth ,i have no idea of time,passes on the set but they didnt have the fractures in the ring or razor sharp edge ,these are just pulled from my car , a g/sa 3650 lbs car tha ran 11:50 to 11:80 depending on air conditions with a 1.529 60 ft ,,i was on the fence about going with the synthetic low weight and it showed that there wasnt enough viscosity witch ended up with metal to metal on hard launch and the tire shake didnt help,,,just asking who runs a 8 3/4 with a heavy car how they are doing with there set up gmonde

Re: 8 3/4 stocker rear
 

george:this a 489 case with mark willaims caps,billet spanners,if i stayed with 85/140 i dont think this would of happened but looking for et some time's cost gmonde

Re: 8 3/4 stocker rear
 

I run a 83/4 in my A stocker and change the gear set every 100 passes max. I as well check it 2 to 3 times during that time as I had one set that was starting to lift the ring gear teeth, very close to disaster. I have a set of gears done by Jim Bailey that I set up and will be using it this year.

Darcy Clarke
AA/SA, A/SA

Re: 8 3/4 stocker rear
 

whats the gear lube you run,,whats the 60' gmonde

Re: 8 3/4 stocker rear
 

I have run different lubes but mainly the shockproof 75/90 synthetic. The 60 foots are typically low 1.30's and I weigh 3540 lbs , I foot brake with no 2 step. The housing is back braced and I use Strange spools with ARP Studs. The 83/4 is good but at certain power levels it has a limit and it is just regular maintenance. I am looking forward to seeing how the gears that Jim did for me work out, I have only heard good things about them.

Darcy Clarke
AA/SA, A/SA

Re: 8 3/4 stocker rear
 

Could be pinion depth not in far enough.

Re: 8 3/4 stocker rear
 

Be thankful that you found it before catastrophe hit. I think that you will be pleased with Jim Bailey's work. An 8 3/4 should hold up in your car. Have you ever seen Darcy's car launch? WOW! I run the same combo as Darcy but in a 3995 lb wagon. I played with 8 3/4s for years and wasted too much money before I finally switched to a Dana 60. Set up 3 race ready 8 3/4 chunks and you've paid for a Dana. I respect that it could be a little slower (not even a tenth) but you cannot win a race when they need a hook to get your hot rod off the starting line!

Good Luck!

Chris Barnes
Wagons of Steel
Stock 6621

Re: 8 3/4 stocker rear
 

I agree. The cracked areas seem to be to the outside of the ring gear. Under load, the outer part of the teeth may be bearing too much of the load. Perhaps this is not the only factor, but I'd sure put the pinion in a little deeper next time.

Many guides to setting up a r&p show a centered pattern on the drive side of the ring gear tooth. However, you can't get enough of a load using a rag to cause drag on the bench, and you should put the pattern to the inside of the tooth. It will spread only to the outside under a real load. Check and you will see that the wear didn't go any farther to the inside under use than it was when set up. OTOH, the wear spread from the mock-up pattern towards the outside of the gear.

Re: 8 3/4 stocker rear
 

Sound's like the pinion depth was wrong to me also.

Re: 8 3/4 stocker rear
 

i normaly run the pinion pattern on the toe rather than the middle of the drive tooth but some times came be real noisey,,but i will have to do that on the next set ,and your right about checking it before the season started , if that had let go i could have lost the trans as well ,,i will contact jim ,,,thanks for the replys gmonde

Re: 8 3/4 stocker rear
 

Sometimes when you set the drive pattern to much to the toe it runs off the heel on the coast side. That could cause the cracks on the end of the ring gear, which I have seen before. I have also seen the cracks in the pinion, in the 5.13 and 5.57 ratios.