Gear ratio help

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tinmidl
Posts: 16
Joined: Thu Jun 23, 2016 7:14 am

Gear ratio help

Post by tinmidl » Sun Dec 04, 2016 9:07 pm

I have a 94 Firehawk #490 of 500
- LT1 V8
- 6 Speed Manual
- 78K miles
- Vortech V1 supercharger
- Front Tire size: 275/40/17
- Rear Tire Size: 285/40/17
- Slicks : 325/60/15
I realized the rearend was leaking all over the garage from the cover and drive shaft. I have a stock 10 bolt, w/ 3.42 gears. Since I'm ripping it apart, should I upgrade gears? Suggestions for ratios? Also when I pulled the difference. Cover there was quite a bit of metal shaving on the cover magnet. Any input would help.

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BLACK-HAWK
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Re: Gear ratio help

Post by BLACK-HAWK » Sun Dec 04, 2016 10:42 pm

4.10's is a popular gear swap. Since your supercharged it might be best to stick with 3.42's. I can't speak for Supers but for turbos, i would have been shifting before boost hit full on if I had 4.10's
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TTOP350
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Re: Gear ratio help

Post by TTOP350 » Sun Dec 04, 2016 11:25 pm

410 s in a 10bolt is a timebomb. Stick w the stock ratio since you are supercharged.
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tinmidl
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Joined: Thu Jun 23, 2016 7:14 am

Re: Gear ratio help

Post by tinmidl » Sun Dec 04, 2016 11:35 pm

Thanks for the knowledge. What about the bearings and such? Should I replace all of it since I have it opened up?
Also what's the best gear oil I belive I have the Auburn rear end so from what I've read NO SYNTHETIC.... I guess it ruins the Brass components. 75W 90 but any recommendations on brand?

NBrehm
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Location: New York

Re: Gear ratio help

Post by NBrehm » Mon Dec 05, 2016 1:16 am

TTOP350 wrote:410 s in a 10bolt is a timebomb. Stick w the stock ratio since you are supercharged.
Agreed. 3.42 is a pretty good all around gear for an M6. Especially with a blower you aren't going to be lacking for acceleration. What I WOULD do is upgrade as much as you can if you are keeping a 10 bolt (weld axle tubes, forged axles, rear end girdle maybe even a C-Clip eliminator, etc etc).
-Nick
2001 Formula Firehawk #293

NBrehm
Posts: 159
Joined: Sun Jun 28, 2015 8:58 pm
Location: New York

Re: Gear ratio help

Post by NBrehm » Mon Dec 05, 2016 1:17 am

tinmidl wrote:Thanks for the knowledge. What about the bearings and such? Should I replace all of it since I have it opened up?
Also what's the best gear oil I belive I have the Auburn rear end so from what I've read NO SYNTHETIC.... I guess it ruins the Brass components. 75W 90 but any recommendations on brand?

Any off the shelf will be fine. It's going to turn to mud anyway ;-). I wouldn't pay the extra for really high end fluid in a stock rear axle unless you are hunting for every .001 at the track.
-Nick
2001 Formula Firehawk #293

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