Rear Gear Selection

[LS1ow]

time to get the new rear peppered in advance of 10 bolt destruction.

I picked up the rear out used out of a 6 speed car, and it has 4.10s in it. So no bueno for me.

Without any confirmation other than word from the previous owner, my car currently has 3.42s in it. With those 3.42, i trapped a best of 124. But i do not remember what RPM i went threw at, nor was i logging data.

The car has a 26" tire, stock geared 60e and makes about 430 on motor and will be getting 100/150 of Nitrous.

Since the rear going is is a ford rear(8.8) i have been made to beleive ford racing provides the best gear quality wise, so i will most likely be going with them.

Making my choices most likely 3.73 or 3.55.


and yes, i tried all those gear calculator things, they blow.

[Blackbirdws6]

Originally Posted by LS1ow

time to get the new rear peppered in advance of 10 bolt destruction.

I picked up the rear out used out of a 6 speed car, and it has 4.10s in it. So no bueno for me.

Without any confirmation other than word from the previous owner, my car currently has 3.42s in it. With those 3.42, i trapped a best of 124. But i do not remember what RPM i went threw at, nor was i logging data.

The car has a 26" tire, stock geared 60e and makes about 430 on motor and will be getting 100/150 of Nitrous.

Since the rear going is is a ford rear(8.8) i have been made to beleive ford racing provides the best gear quality wise, so i will most likely be going with them.

Making my choices most likely 3.73 or 3.55.


and yes, i tried all those gear calculator things, they blow.

What are you spinning the engine to?

I expect you will see 10+ mph with that shot so the maths should be easy on what you will need at the end of a run. Worst case if it's trapping with more bald eagles than anticipated, you can go to a taller tire. Then when you go with the turbos, you will be reassessing this all over again.

[LS1ow]

Originally Posted by Blackbirdws6

What are you spinning the engine to?

6700 iirc

[wretched73]

I think your best bet is running the 4.10s, seeing how your car runs, then reassess from there. They will either work well, or give you better insight into what gear you want next.

[Blackbirdws6]

Originally Posted by LS1ow

6700 iirc

If you are keeping the 26's. 3.73's will get you to 6500 RPM assuming a 135 mph trap speed through the beams.

If you are planning to rodeo a little harder (or this is just a troll thread), then go with the 3.55's to plan for the future. I know you will want to earn the chute.

Edit: For clarification, numbers assume a locked converter.

[The_Bishop]

The 3.42's will be stronger than the 4.10's. I'd give them a shot first and see what happens before spending a bunch of $$ for something you may/may not need. If you o need to pepper a new rear, you'll have an idea on what gearing you'll need based on what you're getting out of the current setup.

Also, figuring out trap RPM with an automagic is hard to pre-calculate as it depends a *lot* on the converter and it's slip on the top end... Unless you have a high zoot mega-lockup-clutch one, in which case RIP transmission?

[sweetbmxrider]

Yeah I'd be curious about converter + spray = how much slip?

[MDSheds_SS]

I will be your guinea pig, spraying 100/150 on a 28 with 410s when AC season is over and I get min to install the rest of the kit.