Need yalls opinion on rear gear ratio
03-11-2014, 08:21 PM
#1
Need yalls opinion on rear gear ratio Ok. I have a Tremec TKO600 5 speed. I currently have a 3.55 gear with a 30.20 tall tire with a 5th gear ratio of 0.82:1. This is way to high for a hot rod. My question is what gear do yall think I should be in going through the traps. Im gonna spin the motor to about 6500 to 6700. Should I be wound out in third gear or should I be in the sweet spot of the power in 4th gear. Looks like my options are 4.11 or 4.56 for the 8.5 10 bolt thats in it. Seems like a 4.30 would be best but I dont think anyone offers that. Probably should post this in another section but there are alot less trolls in here.
03-11-2014, 08:58 PM
#4
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if your set on 4.30's depending on what 8.5" 10 bolt case and carrier you have....
these might work
http://www.summitracing.com/int/parts/mgr-gm10-430/
Or drop to a 28" tall tire and use 4.10s
Bruce
these might work
http://www.summitracing.com/int/parts/mgr-gm10-430/
Or drop to a 28" tall tire and use 4.10s
Bruce
03-11-2014, 09:01 PM
#6
if your set on 4.30's depending on what 8.5" 10 bolt case and carrier you have....
these might work
http://www.summitracing.com/int/parts/mgr-gm10-430/
Or drop to a 28" tall tire and use 4.10s
Bruce
these might work
http://www.summitracing.com/int/parts/mgr-gm10-430/
Or drop to a 28" tall tire and use 4.10s
Bruce
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03-11-2014, 09:29 PM
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If setting up for optimum results, you'll want to be going through the traps in 4th gear over the quarter. All depends on hp/weight and estimated trap speed etc. Are you talking 1/8th or 1/4 mile?
03-12-2014, 04:12 AM
#10
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Well if you are going to run a 33" tyre, you are going to want at least a 4.56 final ratio with such a big tyre. Even with that HP figure and weight, car should still be capable of around 120mph and you'll be lucky to see much more than 5600rpm in 4th gear. Of course any calculation is only ever going to be a rough guesstimate, as there are far too many variables in real world conditions.
What are the engine specs?
What are the engine specs?
03-12-2014, 06:35 AM
#12
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30's @ 4.26 or .430 would be about the same with the different tires.
I woudl add more gear if it were me and go 4.56 or 4.88's
If you are shifting at 6500-6700 you want to run through the lines about 200-300 RPM higher.With 4.56's you coudl run the 30" tires and if its a bit much put the bigger tires on. Also 4.56's are normally easy to get locally used.
Bruce
03-12-2014, 07:42 AM
#13
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Try another 100hp on top of that quite easily, and in a 2700lb car you have the potential for 130mph. Running a 4.56 rear gear will still be a touch tall with a 33in tyre, although you should see around 6000 through the traps in 4th.
03-12-2014, 09:03 AM
#14
If you go 33's with 4.56 that would work also.
30's @ 4.26 or .430 would be about the same with the different tires.
I woudl add more gear if it were me and go 4.56 or 4.88's If you are shifting at 6500-6700 you want to run through the lines about 200-300 RPM higher.
With 4.56's you coudl run the 30" tires and if its a bit much put the bigger tires on. Also 4.56's are normally easy to get locally used.
Bruce
30's @ 4.26 or .430 would be about the same with the different tires.
I woudl add more gear if it were me and go 4.56 or 4.88's
If you are shifting at 6500-6700 you want to run through the lines about 200-300 RPM higher.With 4.56's you coudl run the 30" tires and if its a bit much put the bigger tires on. Also 4.56's are normally easy to get locally used.
Bruce
Just need to do some figuring on the occasional highway run. I just dont want to be doing 2700 or 3000 at 65So where'd you get the idea this is going to make only 415hp? Are you only planning on only using 7 ignition leads?!
Try another 100hp on top of that quite easily, and in a 2700lb car you have the potential for 130mph. Running a 4.56 rear gear will still be a touch tall with a 33in tyre, although you should see around 6000 through the traps in 4th.
Try another 100hp on top of that quite easily, and in a 2700lb car you have the potential for 130mph. Running a 4.56 rear gear will still be a touch tall with a 33in tyre, although you should see around 6000 through the traps in 4th.
That 515 hp guess should make this old truck move out. Right now im between the 4.30 and the 4.56. I have new tires now and they were crazy expensive, so the 33" tires would be in a year or so depending on the amount of fun.
03-13-2014, 07:15 AM
#16
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With the kind of power you should make and the tires you have I woudl start looking for a 8.5" 10 bolt or some other stronger diff. If you drive your car hard or take it to the track a 8.2" 10 bolt will not last long.
That is why I went 8.5" for my 68 nova. It will require a different length drive shaft also....
s60, 9" or some other would be alot stronger and not much different than building a 8.5" strong. With detroit locker, ss axels, c-clip eliminator etc got a fair bit in my 8.5" 10 bolt.
Bruce
That is why I went 8.5" for my 68 nova. It will require a different length drive shaft also....
s60, 9" or some other would be alot stronger and not much different than building a 8.5" strong. With detroit locker, ss axels, c-clip eliminator etc got a fair bit in my 8.5" 10 bolt.
Bruce
03-13-2014, 08:50 AM
#17
Your right but I also compare it to the 7.5 in the 4th Gen F Bodys. I know they gernade often but ive seen alot live for a long time. Im gonna run this one til its done. I actually took this one out of my Chevelle and put a Dana 60 in it. Hell it takes 100 HP to turn that thing not to mention it weighs a ton. When this one dies Ill probably put in a 8.8 from a Ford. 31 spline axels with disc brakes and they come in 2005 and later Crown Vics and Explorers and Ive seen those things in 9 second cars when thry are built right.
