12 bolt in a drag car

hhott71

R.I.P 11/19/18
Lifetime Gold Member
Mar 30, 2001
14,377
Joplin Mo. 64801
I'm using 1968 or 69 GM 4.10 gears in my 12 bolt.
The gears have lived in 3 cars, and have had at least 200,000 street miles. Now they are driven 1 mile at a time, 1/4 of it under hard acceleration from a standing start on a spool with slicks.
 

justincmorris

Veteran Member
Mar 24, 2005
300
Arlington, TX, Tarrant
the older richmond pro gears are great gears for 12 bolts but they changed the metal densisty in the pro gears recently so they are junk for real racing applications unless like I stated you can get your hands on a set that are at least 2 years old. Best bet go with another manufacturer for racing gears. My bro took his 12 bolt out of his car and replaced it with a 9inch because of the same issue you were having.
 

Cardinal

Veteran Member
Lifetime Gold Member
Jun 22, 2003
8,354
Endicott, NY
IF we EVER get it done, our 87 S10 has a narrowed 12 bolt with Moser pro 31 spline axles, spool, and 4.56:1 gears. Our "little" 292 (283 bored .060" over) will be humming through the traps in the 1/4 mile! The local track is 1/8 mile so it shouldn't see that high of rpms unless we go to ESTA.
 

Mike N

Administrator
Staff member
Lifetime Gold Member
Jan 13, 2002
3,069
Spencerport, NY.
12 bolt here. 3600 lb footbrake car running 10.30's @ 130 mph.

Richmond gears that are at least 10 years old, if not older.
 

bbc nova

Veteran Member
Apr 18, 2007
1,124
MN
The 12 bolt I have went for years in a 2800 lb chevelle running mid low 8's in the quarter. He sold it to me cause he didnt think it would take 7's. Been in my car for years. Ive gone low 10's with it and street it.
 

80'427

Veteran Member
Jan 1, 2005
1,886
Fairbury, NE, USA
its in a traction limited 3500lb camaro with 400rwhp. Richmond said it was a power break and to try on over deepen the pinion .004" And see if it helps. Seems to be underpowered compared to others here.
 

bbc nova

Veteran Member
Apr 18, 2007
1,124
MN
80'427 said:
its in a traction limited 3500lb camaro with 400rwhp. Richmond said it was a power break and to try on over deepen the pinion .004" And see if it helps. Seems to be underpowered compared to others here.

A bone stock 12 should take that all day long. Id switch gears.
 

bbc nova

Veteran Member
Apr 18, 2007
1,124
MN
80'427 said:


Dont know who makes good stuff.

Ive had the same ones for the last 8 years. Richmond Pro gears abvously the old ones not the new ones referred to above.
 




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