Today I put a deposit on a full rear-end complete with Richmond 4.10's and an Auburn posi! Yes it's "only" a 10 bolt, but I may upgrade the axles to Mosers or something stronger than stock. Otherwise, it should be a solid rear-end.

My plan is to be able to swap this diff. with the 2.73 diff. currently in my car to go to the track next year. Has anyone run 4.10's with their automatic cars, and at what RPM (roughly) are you crossing the 1/4 mile mark in 3rd gear??? I know with 3.73's it was just over 5000 RPM (maybe 5200? ) @ 105 mph, so theoretically it should be about ~5700 - 5800 RPM.

Have I gone too far?!? I guess I'll find out in the spring! I DEFINITELY need some E/T Streets now!!!!!

 

If you have a tall enough tire to eat up some gear you will be ok.

If you want to play around with tire/gear combos

http://www.f-body.org/gears/

 

Thx for the link. I calculated for an A4, with 245/50/16's, a 6000 RPM redline, and 4.10's, and it says that top speed in 3rd gear would be 112 mph. That will work for me! Then if I build up the motor eventually so I can safely rev it higher (6500 + RPM) it calculates top speed of 3rd gear at over 120 mph!

Ohhhhhh boy..............these gears are gonna be fun!!!

 

Is there any reason you are going for 4.10s??

You could always use 3.42s or 3.73s with a high stall convertor with a high stall ratio to get the same effect as 4.10s.

 

Well, for one thing, it was available off a guy I knew. Secondly, I already "experimented" with 3.73's earlier this year (that's a long story, but I don't have them anymore ). I know what the 3.73's were like on the street and at the track. However, I didn't spend the money on a set of tires (E/T Streets or DR's) so I basically wasted my time because the car just spun the tires all the way through 1st gear, so I cut exactly the same time at the track. What I remember though, is that the engine was turning just over 5000 RPM in 3rd crossing the line, so with 4.10's, it should be running a little higher up in the power band, and as long as I can get traction, it will pull even harder than 3.73's out of the hole.

Oh, and why no converter? Well, it's either $600 for the rear end I bought, or over $1000 for a good torque converter up here in Canada. And gears aren't as hard on a transmission as a torque converter would be. You can't argue that.

 

I think you like it!

 

1000.00 for a TQ get the TCI ssf 3500 stall its only 500.00.

 

500 Canadian dollars?