Cadillac CTS-V - Gears? 3.73 v. 3.55

Specing out a 8.8 and I either want 3.73 or 3.55 gear set. I daily drive my car and it would be nice to have the RPM alittle bit lower in 6th at 75mph. Been in a Cobra w/ 3.55 but much different power levels haha.

Will the change to 3.55 gears be noticeable considering i just have boltons? Always thought the rule of thumbs was that the more power you have, the taller the gearing you can get away with.

Anyone running anything different then 3.73?

If you plan on sticking with just bolt ons, I would say 3.73s are the best. If you want to go F/I, 3.55s is what I would do.

The only real difference you will notice is the better MPGs on the highway and a slightly more usable 1st and 2nd gear.

3.55's are good for stoplight to stoplight. And actually with a supercharger I'd keep 3.73's or go even higher. Since you have the torque with FI it's easier to do that

4.10's here. Fuck gas mileage and long first gears... Lol

3:55's in my 8.8 swap. The car is much more enjoyable to drive now.

Honestly... I wish at times my buddy would have stuck with 3.73's since its a daily but with that big 6th gear... It didnt make it much worse. I'm not interested in going with a 3.55. To each their own but I'd either stay 3.73 or go 4.10. I like having the torque happy gear to get the car moving quick down low.

Those ratios are really close anyways. Not like you are going from a 3.73 to a 3.23 or 2.73. You can keep the 3.73 and go to a slightly taller tire next time to gain some driveability or go 3.55 with a shorter tire to keep performance.

I have always felt that 3.73s are a great gear for best of both

Specing out a 8.8 and I either want 3.73 or 3.55 gear set. I daily drive my car and it would be nice to have the RPM alittle bit lower in 6th at 75mph. Been in a Cobra w/ 3.55 but much different power levels haha.

Will the change to 3.55 gears be noticeable considering i just have boltons? Always thought the rule of thumbs was that the more power you have, the taller the gearing you can get away with.

Anyone running anything different then 3.73?

3.55s would drop the RPM from between 2000 and 2050 to 1900 to 1950... not a real large drop IMO.

=RPM/(Diff Ratio * Trans Gear Ratio) * Tire Diameter in inches *0.002975

Tire size on standard 18s on stock tire is 26.7, rear is 3.73, and trans ratio for 6th is 0.57

Id stick to 3.73s, cause if you ever want to throw a cam in it your gonna want at least 3.73s. The difference like said above is tiny so I highly doubt you would see much difference in gas mileage either.

My car cam'd with 4.10's still gets an average of 22mpg on the highway at 70-75. Old car got 24mpg at the speed so not a huge loss considering the big performance difference.

If you plan on sticking with just bolt ons, I would say 3.73s are the best. If you want to go F/I, 3.55s is what I would do.

The only real difference you will notice is the better MPGs on the highway and a slightly more usable 1st and 2nd gear.

3:55's in my 8.8 swap. The car is much more enjoyable to drive now.

These guys hit the nail on the head...if you are going FI use the higher (lower numerically) gears such as 3.55 or 3.42. Boost needs a load to work against and the really short gear ratio's in our trans doesn't help any. Take a stroll through the FI section here and you will see quite a few people running 9's and 10's with 2.73 and 3.08 ratio's on boost.



3.55s would drop the RPM from between 2000 and 2050 to 1900 to 1950... not a real large drop IMO.

=RPM/(Diff Ratio * Trans Gear Ratio) * Tire Diameter in inches *0.002975

Tire size on standard 18s on stock tire is 26.7, rear is 3.73, and trans ratio for 6th is 0.57

This is correct, but sixth gear is not the only one used. The 2.97 first gear ratio will feel a LOT different with 3.55's than with the stock 3.73's. I believe that 3.73 is the overall optimal diff ratio, just not with our trans.

These guys hit the nail on the head...if you are going FI use the higher (lower numerically) gears such as 3.55 or 3.42. Boost needs a load to work against and the really short gear ratio's in our trans doesn't help any. Take a stroll through the FI section here and you will see quite a few people running 9's and 10's with 2.73 and 3.08 ratio's on boost.
.

Eh, cant say all boost. Prochargers to a certain power level like gear. 3.73s to 4.10s since they build boost with rpm. Roots and twin screws generally like 3.55s-3.73s or even 4.10s. Turbos like load so 3.27s-3.55.

These guys hit the nail on the head...if you are going FI use the higher (lower numerically) gears such as 3.55 or 3.42. Boost needs a load to work against and the really short gear ratio's in our trans doesn't help any. Take a stroll through the FI section here and you will see quite a few people running 9's and 10's with 2.73 and 3.08 ratio's on boost.





This is correct, but sixth gear is not the only one used. The 2.97 first gear ratio will feel a LOT different with 3.55's than with the stock 3.73's. I believe that 3.73 is the overall optimal diff ratio, just not with our trans.

Oh yeah, I know. Just was mentioning sixth because OP wanted to know how it would affect his 6th at 75mph

OP- 3.73 would be my choice out of the two options.
4.10 would be my ideal choice when using a T56 or T6060. - And yes, thats with power adders.


Boost needs a load to work against and the really short gear ratio's in our trans doesn't help any.

I dont agree. You cant categorize all types of FI into a group 'boost'. As mentioned, Centrifugal type. This would apply to Turbos more than other types of FI.

Thanks for all the responses... based on everything above im going to stick with 3.73. MPG is really not that important since the gain would be minimal

I went with 3.89's combined with the Maggie... it's a rolling second gear burnoutfest. More tire is definitely required... but I must say... walking on new stock v's, blown Challengers, and holding up to elder 600cc motorcycles is really a LOOOOOT of fun.

FWIW: I had a chance to change out my gears with my 9" rear end, and I stuck with 3.73's

Lolly if you had more power maybe you'd change your mind ;).... hurry up on some big power.

Lolly if you had more power maybe you'd change your mind ;).... hurry up on some big power.

I'm trying to figure out what route I'm going. All these hookers and blow are getting my mind off track!

Where are people getting their 8.8 Ford rears from ?

Where are people getting their 8.8 Ford rears from ?

Creative Steel
-Pumpkin either supplied by them or themselves.

Creative Steel
-Pumpkin either supplied by them or themselves.

Isn't their diff close to 2K ? The difference between the full kit and the other is $2k. Besides the nuts and bolts what else is missing from the half kit ?

I'm trying to figure out what route I'm going. All these hookers and blow are getting my mind off track!

LOL, though, that does sound like fun...
maybe this will help...?

https://vimeo.com/42096122

Though I hate the ashtray gauges... i really need to change that.

woot... partial CS kit is on the way..:bomb: 4 weeks for DSS to fab up my drive shaft and axles.. i got the built outer CVs since i'm providing the diff

LOL, though, that does sound like fun...
maybe this will help...?

https://vimeo.com/42096122

Though I hate the ashtray gauges... i really need to change that.

:nod::nod:sounds like a leer jet

woot... partial CS kit is on the way..:bomb: 4 weeks for DSS to fab up my drive shaft and axles.. i got the built outer CVs since i'm providing the diff



:nod::nod:sounds like a leer jet

What did that run ? With the built outer CV's you don't need to take your stock ones apart ? What else did you need to buy to complete it ?

Thanks