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i want to replace the stock gear ratios. what gear ratios 3.73, 4.10, 4.30
rear tires 305/45R18
 

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i want to replace the stock gear ratios. what gear ratios 3.73, 4.10, 4.30
rear tires 305/45R18

I changed mine to 3:73s and was definitely a nice change.

With your tire size shown, I'm not sure what you will need though?
 

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Yeah 373's
+1 The 3.73 is a good gear for around town and also for road trips.

This is the gear the car should have came from the factory.

Cal
 

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That's too techie for me, we need 68Fastback on this one.
 

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...or maybe George?:D
 

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Do a search on 'ratios' and you'll see the topic discussed by 'croz98gt'. He shows you the different speeds at different RPMs for the 3.73, 4.10 and 4.56 gears.
 

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Do a search on 'ratios' and you'll see the topic discussed by 'croz98gt'. He shows you the different speeds at different RPMs for the 3.73, 4.10 and 4.56 gears.
Beat me to it. Thread was "What Gear Should I Use 4.56, 4.10, 3.73". Has all you need.
 

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Sprint and I were just talking about this svtbird, this might be timely since installing your TVS. Have you done the gear swap yet? If not, you might want to wait to get on the track before switching gears, 3.73's might be too much for the track with the RWHP you're putting down now? Anyway, as I said above, Sprint PMed me about gears and the following was my reply,

"I'm running 3.73's which were great with about 550-560 rwhp but since I went up to 610 rwhp the 3.73's are a little too much especially coming out of turns in second gear, the tires will spin if you get on it too quickly; it's managable but you can't go to WOT after the apex of a turn and ride it through to the straight which I was able to do on most turns in second when it was 559 rwhp with 3.73's.

With the mods that you are planning, "93 octane tune but will be adding a pulley & CAI ", you should get up to the 550-560 rwhp level and at this level, as I said above, I think the 3.73's are a very good choice. Are you considering upgrading the heat exchanger? I think this a great mod for a street/track car, it doesn't add HP but it keeps you from loosing HP due to heat soak and we both know how hot it gets on the track in the summer time.

I've been waiting for the 2.9 Whipple super charger to become available which will take me to my 670-680 rwhp goal, I will probably go down to 3.50's or back to the stock 3.31's to help keep the tires from spinning with the higher HP; I'll also be looking at changing the differental and axles next time around as well.

Hope that helps,
WP"
 

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Sprint and I were just talking about this svtbird, this might be timely since installing your TVS. Have you done the gear swap yet? If not, you might want to wait to get on the track before switching gears, 3.73's might be too much for the track with the RWHP you're putting down now? Anyway, as I said above, Sprint PMed me about gears and the following was my reply,

"I'm running 3.73's which were great with about 550-560 rwhp but since I went up to 610 rwhp the 3.73's are a little too much especially coming out of turns in second gear, the tires will spin if you get on it too quickly; it's managable but you can't go to WOT after the apex of a turn and ride it through to the straight which I was able to do on most turns in second when it was 559 rwhp with 3.73's.

With the mods that you are planning, "93 octane tune but will be adding a pulley & CAI ", you should get up to the 550-560 rwhp level and at this level, as I said above, I think the 3.73's are a very good choice. Are you considering upgrading the heat exchanger? I think this a great mod for a street/track car, it doesn't add HP but it keeps you from loosing HP due to heat soak and we both know how hot it gets on the track in the summer time.

I've been waiting for the 2.9 Whipple super charger to become available which will take me to my 670-680 rwhp goal, I will probably go down to 3.50's or back to the stock 3.31's to help keep the tires from spinning with the higher HP; I'll also be looking at changing the differental and axles next time around as well.

Hope that helps,
WP"
I do have 373's already and I did have the car on the track last year . The hP at the time was 556 rwhp. I found it difficult to get the power to the ground comming out of the turns even in 3rd gear. After that experience I too had thoughts of going back to the 331's. With the flat torque #'s this engine produces esp with the kind of hp #'s I will be getting with the stage 3 TVS ( 680rwhp) 331's would be better suited for the open track IMO also.
IMO Sprint is absolutely correct in his conclusions on this issue.

That said now that I am done with much of my suspension upgrades I thought I would take it out on the track once again to test it before making that decission or even any further suspension decissions either for that matter.

George....


PS : Each of us should have a long range goal for our cars in terms of ;;;How we plan to use the car, how much HP we want to have without internal engine work needing to be done , ect. Then we can make the best choices in regards to the direction we want to go whether for street use, drag racing or open track. For most of us it will be a combination of mostly street with occasional track or strip. Very few will be soley dedicated to racing. This should dictate what we do and what we don't with suspension and power. There is always the tempation to go too far with mods and risk loosing the fun and dependability factor we get with everyday steet driving .
I have learned this lesson long ago with my T-Bird and won't make that mistake with this car. I want to be able to hop in and drive it across country or have an occasional fun day on a road course somewhere. Yeah I might not be the fastest car on the track but I'll have fun none the less and enjoy the drive home too.
 
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