i have a 1991 rs with 350 tbi 700r4 and i was wandering if i put 4 10 gears in how much slower would my car be on topend and how far off will the speedo be

 

well it would be nice to know what gears your running now...

 

it has the originals do you know what they came with

 

I currently have 2.73 with a 700r4. If you go to 700R4.COM - Bowtie Overdrives they have a calculator to tell you speed and RPM for any given gear set. For example I am going to put in 3.73 and the RPM will be around 2500 RPM at 75MPH,

 

2500 is still a real low RPM on the highway, IMHO, not evne really working the engine at that low of an RPM really at all, most engines anyways

i think you would be way plenty fine with 4.10 for performance even with a stock engine and everything

i wish i could get something like 4.10 for any of my cars

hard to get, very difficult, virtually everything was gas mileage geared in the 70s and 80s unfortunately, cept little mini trucks and then most of the the 3/4 and 1 ton and larger trucks, 3.21 was the highest ratio in the GM 3/4 and 1 tons, 4.56 was the lowest, 73-up anyways

3.89 is in my toyota 2wd pickup and it only weighs 2720 with me in it is whats funny

3.42 and 3.73 are dirt common in the s series trucks

4.00 something is supposed to be reall common in datsun trucks and such

 

thanks but i was told that 4.10 won't fit in my rear end

 

If you have a 7.5" 10 bolt, then 4.10's will fit. They make them for 2 and 3 series carriers.

They have the new 3.90 set available as well, I may go that route since 4.10's were too much and 3.73's were just too little.

 

The only problems you can come across when you want to swap out these gears is:

The gears must match the same series as the carrier.

If the gears that are in the car now are 2.73-3.08 you have a 2 series carrier, if the gears are 3.23-3.73+ you have a 3 series carrier OR someone has used a special gear set made to fit 3 series gears onto a 2 series carrier.

And the obvious if its a 9bolt you need 9bolt gears, if its a 10 bolt you need 10bolt gears....

 

With a factory cam, cruising rpm higher than about 2400 is gonna cost you fuel, and since that cam is also only making power to around 4500, using that low of a ratio isn't gonna help you performance wise, except the intial take-off. So now your car has power till midway through 1st...........and then you're out of motor......