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Author Topic:   Rear End Gears
Dirt Full Roller

Total posts: 69
posted February 23, 2003 05:47 AM  
Hi Gear Heads, In a 85 Buick Regal i still have a stock rear end gear.My ? is. Do they make gears of say 3.73 and 4.10 for ford and chevy.Or does ford have their own and chevy their own, in 10 and 12 Bolt gears.So is the 4.10 gear for a 10 bolt the same as a 4.10 for a 12 bolt.Also, in a chevy 10 bolt will either one of these gears 3.73 or 4.10 fit and which one would best for a 'stock' 350 sbc? I think the rear end is metric.??? The studs are metric. Thanks for any help.

Dirt Forum Champ
Total posts: 570
posted February 23, 2003 02:45 PM  
Wow, That is a many part question. Lets see if I am interpreting it correctly.
None of the chevy stuff will interchange with the ford stuff. Chevy 10 and 12 bolts are different also, so the gears don't change over either. Fords 9inch is probably the best rear end ever invented for racing. The Dana rear is a close second, but chevy is (this is hard for a chevy fan to say) way behind on getting a package that will work for us saturday night guys together. The one thing about a chevy 10 bolt is, they are a dime a dozen at the wrecking yard, if your car can run one without breakage every other night, you can get another out of the yard for cheap. P.S. I have a chevy 10 bolt set of gears that I would part with.
There are some other things to consider too and I can't remember how to determine what sizes the 10 bolts are but they are 7.5 and 8.5 and others. Your Buick should be a 8.5 I believe, but you better make sure. any gear will fit in the rear end as long as its made for it. I believe some gear makers make up to 600 for the 10 bolt. You will have to call the gear manufacturer. The best gears for a sbc are try them in practice and see what the engine likes. if you run a 3/8th mile track you should run the 3.73 down to 3.43. Try to get a 6.30 to 6.88 final drive.

[This message has been edited by uforacing51 (edited February 23, 2003).]

Dirt Forum Champ
Total posts: 5390
posted February 24, 2003 08:41 AM  
just a thought someone told me that s-10's some times use a bigger pinion bearing.

Dirt Roller

Total posts: 12
posted February 24, 2003 09:51 PM  
hi A good chance your 85 Regal has 7.5 ring gear. We run these metric cars and all have 7.5 rear ends. One thing to keep in mind a 9inch ford will work if you change the brackets but a lot of the 9 inches are a lot wider housings than your metric car has.You can get a 3.73 or 3.42 for that 7.5 but also your stock rear end might have a 2.72 or 2.41 ratio which will have to a thicker ring gear or a spacer to fit the carrier.

Dirt Forum Champ
Total posts: 5390
posted February 25, 2003 11:49 PM  
I run a78 monte with a 7.5 rear end. Run t350 in 1st gear on 1/2 mile track. With the first gear I can run all stock easy to find gear ratio's 2.23 or 2.42 or 2.73 it all depends on the size of the rear tire you plan to use. Those gears put final drive at 5.80- 6.30. I think that 6.88 final is too tall and would put a STOCK 350 way above its max hp rpm.

my two cents

Dirt Freak

Total posts: 474
posted February 26, 2003 09:21 PM  
I think a t350 in 1st gear and a 273 rear gear will give you roughly 680 final.We use this on a 1/3 tacky med banked clay track and stay around 6500 to 6800max rpms(350cid)
Cheap and abundant too.

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