Which gears to choose?
#1
Which gears to choose?
Hi,
Got a 72 Cutlass with a LS/4L60E and 2.73 open diff. Tires are now 275/40-19 (still trying to decide if it looks right...). Opinions are welcome..
The reason for that is that Im about to install LS1 brakes (98-02 F-Body) on all four corners and need extra rim cleance to allow bigger rotors. Im also planning to upgrade to a posi/LSD since I have to pull the axels anyway.
The 2.73 are good for highway and long trips, but want a more "fun" car. I was thinking 3.73, but when I changed the wheels from original (26.5" to 27.7" diameter) it seamd to be even more willingly to "burn" the tire than before with the originals.. Does that make sence?? In theory when increasing the tire diameter it would have the same effect as lowering the gears even more.. A posi will help a bit with the wheel spin, but still wondering witch gears would the best choice..
Thanks
Morten
Got a 72 Cutlass with a LS/4L60E and 2.73 open diff. Tires are now 275/40-19 (still trying to decide if it looks right...). Opinions are welcome..
The reason for that is that Im about to install LS1 brakes (98-02 F-Body) on all four corners and need extra rim cleance to allow bigger rotors. Im also planning to upgrade to a posi/LSD since I have to pull the axels anyway.
The 2.73 are good for highway and long trips, but want a more "fun" car. I was thinking 3.73, but when I changed the wheels from original (26.5" to 27.7" diameter) it seamd to be even more willingly to "burn" the tire than before with the originals.. Does that make sence?? In theory when increasing the tire diameter it would have the same effect as lowering the gears even more.. A posi will help a bit with the wheel spin, but still wondering witch gears would the best choice..
Thanks
Morten
#2
Somewhere in my huge stash of magazines, I have a "Team T/A" newletter, published by B.F. Goodrich. One of their race tire engineers stated that wheels ONLY need to be big enough to clear the brakes. Look at NASCAR, Formula 1, and virtually every other major race - all the cars run a fair amount of sidewall.
You have tall tires, which hurts the overall gear ratio. BUT, you now have no sidewall to dampen the initial hit of throttle. The sidewall performs as an energy storage device, for linear accelleration. The sidewall will absorb some of the initial energy to allow the car to get moving, then return the energy. The less sidewall you have, the greater the chance of spinning (and NOT accellerating).
A 3.73 rear gear will feel like a 2.61, when the transmission shifts into overdrive. With a lock-up converter, elminating the slippage will make if feel like an even higher gear. As long as you kept the fuel injection and have it tune properly, that should be a good combination.
You have tall tires, which hurts the overall gear ratio. BUT, you now have no sidewall to dampen the initial hit of throttle. The sidewall performs as an energy storage device, for linear accelleration. The sidewall will absorb some of the initial energy to allow the car to get moving, then return the energy. The less sidewall you have, the greater the chance of spinning (and NOT accellerating).
A 3.73 rear gear will feel like a 2.61, when the transmission shifts into overdrive. With a lock-up converter, elminating the slippage will make if feel like an even higher gear. As long as you kept the fuel injection and have it tune properly, that should be a good combination.
#4
#5
Somewhere in my huge stash of magazines, I have a "Team T/A" newletter, published by B.F. Goodrich. One of their race tire engineers stated that wheels ONLY need to be big enough to clear the brakes. Look at NASCAR, Formula 1, and virtually every other major race - all the cars run a fair amount of sidewall.
You have tall tires, which hurts the overall gear ratio. BUT, you now have no sidewall to dampen the initial hit of throttle. The sidewall performs as an energy storage device, for linear accelleration. The sidewall will absorb some of the initial energy to allow the car to get moving, then return the energy. The less sidewall you have, the greater the chance of spinning (and NOT accellerating).
A 3.73 rear gear will feel like a 2.61, when the transmission shifts into overdrive. With a lock-up converter, elminating the slippage will make if feel like an even higher gear. As long as you kept the fuel injection and have it tune properly, that should be a good combination.
You have tall tires, which hurts the overall gear ratio. BUT, you now have no sidewall to dampen the initial hit of throttle. The sidewall performs as an energy storage device, for linear accelleration. The sidewall will absorb some of the initial energy to allow the car to get moving, then return the energy. The less sidewall you have, the greater the chance of spinning (and NOT accellerating).
A 3.73 rear gear will feel like a 2.61, when the transmission shifts into overdrive. With a lock-up converter, elminating the slippage will make if feel like an even higher gear. As long as you kept the fuel injection and have it tune properly, that should be a good combination.
Thanks for a good answer!!
Morten
#6
Pulled the axels and started the LS1 brake conversion. Its a bit different than the C-clip axels since my rear end is a bolt on axel, but I have it figured out now.
My question today is regarding the diff carrier.
Is there a difference between the c-clip carriers and the bolt on axels carriers?
Will a posi from a Chevrolt 8.5 10 bolt fit in my as long as the spline count and carrier series are the same?
If not, any recomendations?
Adding a pic just to make shure im not mistaken and it is not the 8.5. Havent done any measurements yet.
Anyone know the part no for the axel bearings?
Thanks!
My question today is regarding the diff carrier.
Is there a difference between the c-clip carriers and the bolt on axels carriers?
Will a posi from a Chevrolt 8.5 10 bolt fit in my as long as the spline count and carrier series are the same?
If not, any recomendations?
Adding a pic just to make shure im not mistaken and it is not the 8.5. Havent done any measurements yet.
Anyone know the part no for the axel bearings?
Thanks!
Last edited by CutLS442; November 9th, 2016 at 06:21 AM. Reason: adding question
#7
I remember reading some posts by Brian Trick were I think he said you can use the c-clip diff with the bolt in axles. The only difference is the side gears have a recess or something for the c-clip clearance whereas the side gears for the bolt in axles don't.
#8
The side gear has a recessed pocket for the c-clip to retain the axle in it.
Good luck, Jim
J D
#10
Thanks Kenneth,
Can anyone confirm this? Im about to order a posi with 3.73 gears and I want to make shure I get the right parts.
I live in Norway and even if the parts are easily bought in the States, freight cost/time and customs work against me Especially if I get the wrong parts.. Ask me how I know
Any suggestion of diff part no.?
Thanks!
Can anyone confirm this? Im about to order a posi with 3.73 gears and I want to make shure I get the right parts.
I live in Norway and even if the parts are easily bought in the States, freight cost/time and customs work against me Especially if I get the wrong parts.. Ask me how I know
Any suggestion of diff part no.?
Thanks!
#12
Pulled the axels and started the LS1 brake conversion. Its a bit different than the C-clip axels since my rear end is a bolt on axel, but I have it figured out now.
My question today is regarding the diff carrier.
Is there a difference between the c-clip carriers and the bolt on axels carriers?
Will a posi from a Chevrolt 8.5 10 bolt fit in my as long as the spline count and carrier series are the same?
If not, any recomendations?
Adding a pic just to make shure im not mistaken and it is not the 8.5. Havent done any measurements yet.
Anyone know the part no for the axel bearings?
Thanks!
My question today is regarding the diff carrier.
Is there a difference between the c-clip carriers and the bolt on axels carriers?
Will a posi from a Chevrolt 8.5 10 bolt fit in my as long as the spline count and carrier series are the same?
If not, any recomendations?
Adding a pic just to make shure im not mistaken and it is not the 8.5. Havent done any measurements yet.
Anyone know the part no for the axel bearings?
Thanks!
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