12 bolt gear breaking problems....

[ericsz]

Thanks so much guys, I knew I get some real answers from you guys, I keep hearing people say welp its time for a 9 inch. You guys have proven differently which is why I asked you folks...Thanks a lot!

[SSDiv6]

Are you using a solid spacer or a crush sleeve in the pinion? If you have a crush sleeve, switch to a solid spacer with shims.

[Jeff Niceswanger]

Eric,we finally gave up and did put a nine inch in.But back when we ran a 5.57 gear we never broke any gears.It wasn't until we started running a 6.00 gear and the pinion got so small that every 50 runs or so it would bust one.We set them tight, loose, bought MW caps,T/A cover etc.... Alot of it has to do with weight.We know alot of folks with the lighter class cars that run a twelve bolt and punish the crap out of them and they don't have problems.But when you get over 3100 or 3200 pounds ( our car is @ 3255 in F) they are on the edge,especially with the steep ratios. Buy the way I have a 5 gallon pail of that Redline Shockproof 140w gear oil that never has been opened setting here collecting dust. Anybody give me 50 bucks ?

[ericsz]

I am in fact using a Crush Sleeve, the car also has a Richmond Mini Spool in it.

[Mark Ruset]

Eric I've been running a 12 bolt 5:14 Richmond street gears for the past 3 years and have had no problems I run a 68 camaro in G automatic and launch about 2600 rpm. I feel the key to longevity with a 12 bolt is pinion depth. You ensure that both the ring and pinion are getting the most contact when you are dead on this, will make for long life.

[SSDiv6]

Get rid of the crush sleeve and use a spacer kit with shims. This will maintain the pinion depth. The shock everytime you drop the clutch will have an effect on the crush sleeve.

[JDEMARZO]

I used a street gear with a 31 spline axle in a G/SA (3250 lbs) for 15 years with no breakage, same gear set. Leaving on the converter is different than leaving on a trans brake. I have a A/SA with a pro gear because all the other A/SA cars ripped the street gears out within 10 runs on a 2-step or foot braking not even a trans brake.

I really do no think you can use a street gear with a trans brake.... Too much stress to the gear set on the launch. If A/S (leaving @ 7000 plus ) and super stock cars using trans brakes are using a 12 bolt your combo should be fine with a pro-gear with the trans brake. Buying pro gears is lot cheaper than changing the rear to a 9 inch.

J.DeMarzo

[Harry 6674]

Even a 9" with a transbrake should use a pro-gear. The shock of the transbrake is hard on parts. Will find the weak link for you. Weight is a factor in all this.