1997 Formula Rear gear

**BARNESGN** · 10-25-2017, 08:41 PM

Looking at a car with a 2.73 rear gear 6 spd Manual. Other than the ring gear, what else needs to be done to switch it to a 3.42/ 3.73. Tune, abs change?

**Sahara54** · 10-25-2017, 09:51 PM

If im not mistaken the M6 cars came with 3.42"s. If have 2.73's you should just need the gears for a series II carrier, and a re-tune for the axle ratio to correct the speedo.

**Injuneer** · 10-25-2017, 11:38 PM

Sahara is correct. All 1994-2002 6-speed cars left the factory with 3.42:1 (GU6 on service parts tag) gears. Only the 1993’s came with 2.73 or 3.23 because of the higher numerical 1st gear ratio in the two T56’s used that year. You need to know exactly which gears you have to get the right size replacement gears (ring gear thickness varies between 2-series and 3-series carriers).

7.625” 10-bolt gear set, install kit, GL-5 80W-90 gear lube, GM limited slip diff (LSD) additive.

Install kit can include things like bearings, shims, pinion seal, crush sleeve (or solid spacer like Ratech), pinion nut, ring gear bolts. You can get kits with less parts, but replacing things like bearings and ring gear bolts is a good idea on a 20-year old car. Might also want to order new axle bearings and seals.

You also might want to consider 4.11’s with the T56. When my car was still a 6-speed I went from 3.42 to 3.73, and always wished I had gone to 4.11. The deep 5th and 6th overdrive gears actually become useful.

**BARNESGN** · 10-26-2017, 07:33 AM

The car's for sale site has it listed as a 2.73. My 88 Formula 5 spd WS 6 had a stock gear of 3.45 borg warner if memory serves correctly. My dad and I put a 3.91? I believe but I only drove it a few times afterward (I joined the Army). And can't really remember the difference in power.

Injuneer you seem like the old school Drag racer. What does it take to hook with a manual trans-slicks-at 4-5000 rpm. I want a project that can cut some 1.4-1.5 60ft times

**95 blackbird** · 10-26-2017, 07:58 AM

Injuneer is correct, don't waste your time putting 3.73's in a 6 speed car.
Go 4.10's or 4.30's. Ask me how I know.

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**Injuneer** · 10-26-2017, 08:39 AM

You need a good clutch, good suspension, sticky tires and 5K clutch dumps. The stock 10-bolt will not be happy.

For suspension, consider tubular LCA's, LCA relocation brackets, adjustable torque arm, and front drag shocks/springs. Disconnect front sway bar. Maybe an air bag in the right rear spring.

**agenthol302** · 10-26-2017, 02:23 PM

depending where you are you might need some power to help hit that 60 ft

**MoeHorsePower** · 10-26-2017, 03:46 PM

[QUOTE=Injuneer;483153]You need a good clutch, good suspension, sticky tires and 5K clutch dumps. The stock 10-bolt will not be happy.

For suspension, consider tubular LCA's, LCA relocation brackets, adjustable torque arm, and front drag shocks/springs. Disconnect front sway bar. Maybe an air bag in the right rear spring.[/QUOTE

^^^ What he says, suspension and the shocks make a huge difference, I had all of the suspension parts, Tq arm, Tubular LCA, ect and my 60 ft was still like 1.9-2.0, then I installed QA1 coil overs in the front and adjustable QA's in the back, adjusted the setting and cut a 1.55 60 ft, but then again it was at 5 grand dumps with a little over 700 rwhp.

**Injuneer** · 10-27-2017, 10:13 AM

Originally Posted by agenthol302

depending where you are you might need some power to help hit that 60 ft

Good point, I should have mentioned that. And dropping a few 100# of excess weight will go a long way.

**Stormyweather** · 10-27-2017, 04:59 PM

I get only 13' s and a frightening 105 ish with my A4 and 3.23s at the trap. an I too could stand to lose 100#s personal and a bunch of it from the car as well

but I wonder what the trap speed would be if I went to 4.11s?

It's not how fast you mow. It's how you mow fast.