Change rear gear ratio-cost

[Rmodeler]

I have an 82 with std. rear end. I thought about having it changed to a higher gear ratio. Now it is only turning 2K @ 80mph. I know that I would sacrifice gas mileage, but I don't do over the road driving and would like a little more snap driving local. What ratio would be good to use, and if I should do it at all? What kind of cost would I be looking at?

 

[fine69]

What ratio would be good to use, and if I should do it at all? What kind of cost would I be looking at?

Do you have an auto or manual tranny?

 

[Rmodeler]

Auto-no choice in 82

 

[Glensgages]

I had the 2.87s swapped-out for 3.73s 4 years-ago, and it immediately made the car run quicker:
I still got 17+ MPG while breaking them in without trying!

I recall my costs were $135 for the ring & pinion (new, from Drive-Train, a shop on Long Island ), and another $450 for a buddy I knew to do the swap, supply miscellaneous parts, fluid, and gaskets, then switch both the drive & driven gear in the transmission to properly recalibrate speedo, for a total cost of less-than $600

 

[minifridge1138]

I'm really tempted to do this to my '82. It seems a lot less invasive than heads/cams/pistons.

Thanks for the info!

 

[Chas]

I have a 350 auto and it had a 3:05 gear in it....at 70mph it would turn 2600 rpm with that gear.
I had to replace mine when the ring bolts backed out and trashed the inside of the housing making it no good for a core deposit.
I had a 3:55 gear installed and they were able to match the speedometer gear perfectly to my gage...with in 1 mph.
The rpm's at 70 mph now are at 3700 rpm and it has alot to offer still....it jumps at the slightest press of the pedal and burns the 60's off the back out of the hole.
What a great diffrence in performance...i cant help much on price but it really made it more enjoyable to drive.

~Chas:cool

 

[Glensgages]

....it jumps at the slightest press of the pedal and burns the 60's off the back out of the hole.
What a great diffrence in performance... it really made it more enjoyable to drive.

Yeah..... driving the rolling hills of S.W. Taxylvania with 2.87s and the A/OD trans sucked pretty-bad, but with 3.73s, the RPMs were kept high-enough that the transmission wasn't constantly upshifting/downshifting:
I was told that ZIP Products have 4.10 gear-sets that will go into the Series-3 Dana-44 carrier, but I couldn't find them, and they didn't return my calls, so I settled for 3.73s

 

[Rmodeler]

I think that I could add that to my "little" to do list for this winter. Since I have most of my work done by a friend-at his garage- the other half would never know the difference, just general repair work, etc. being done!!

 

[Crimson Thunder]

If you do more city driving than highway driving,steeper gears will give you better gas mileage.With the torque multiplcation of the new gears,you won't have to use as much throttle(less gas) to get your car rolling and up to speed.I would go with one of the exchange services offered by one of the Corvette suppliers(Mid America,Ecklers etc.)It is probably more costly than a gear swap but less hassle and maybe a warranty.

 

[asmith]

I have a 350 auto and it had a 3:05 gear in it....at 70mph it would turn 2600 rpm with that gear.
I had to replace mine when the ring bolts backed out and trashed the inside of the housing making it no good for a core deposit.
I had a 3:55 gear installed and they were able to match the speedometer gear perfectly to my gage...with in 1 mph.
The rpm's at 70 mph now are at 3700 rpm and it has alot to offer still....it jumps at the slightest press of the pedal and burns the 60's off the back out of the hole.
What a great diffrence in performance...i cant help much on price but it really made it more enjoyable to drive.

~Chas:cool

You better check your gear ratio or speedo cause 3:55 gears do not make 3700 rpms at seventy. :ugh Vegas

 

[Chas]

You better check your gear ratio or speedo cause 3:55 gears do not make 3700 rpms at seventy. :ugh Vegas

Well, you registered just to reply my post....excellent work.

~Chas

 

[Rmodeler]

What would the rpms be at 70 with the 3.55?

 

[Vettehead Mikey]

You better check your gear ratio or speedo cause 3:55 gears do not make 3700 rpms at seventy. :ugh Vegas

True, but 4.11s do!

 

[Vettehead Mikey]

What would the rpms be at 70 with the 3.55?

3150 with 26.5 inch tires

 

[Chas]

i just call it as i see it....must need to have all my gages fixed. thanks for all the great info

 

[fine69]

I have 3.70:1 gears in my Vette. The RPMs are around 3150 or so @ 60 mph... at 70 mph, it's more like 3400. It's a good ratio. For me, anything more would be too intense - especially on the highway, etc.

I also have 3.73:1 gears in my Camaro, and they are also good.

 

[Glensgages]

What would the rpms be at 70 with the 3.55?

..... 'assuming' you have a non-locking, OEM-brand converter, the formula to calculate that would be:

MPH x GR (Gear Ratio ) div/by .9 (10% slippage in the torque-converter ) div/by .006 div/by 1/2 TH (Tire Height )

I believe with a 255/60R-15 that is typically 27.4" tall, you would be turning about 3360 RPM to run 70 MPH with 3.55s.