3.90:1 Differential Advice Please (1600) [[WTB?]]

[eastsidebimmer]

.

My '71 1600 is handsomely equipped with a 4.11:1 and I was considering swapping out for a 3.90:1 to help keep the revs down at today's highway speeds. Has anyone experimented with this swap? Would a move to a 3.64:1 make the car too super dog slow?

And finally, anyone have a known good 3.90:1 for sale? (shipping required)

Thank you, -=Ben

[jrkoupe]

Ben

Back in the day I had a hot rod 1600 w/ 4 11'........I like the 3.9s waaay better.........a buddy had that set up...

I wouldnt do 3 64s......

oh....Id like that flat gas cap....!!!!!....pls let me know.

[Guest Anonymous]

Great question! I had a cammed 1600 with with sidedraft with the 3.64. Fair at best. Got the 390 limited slip much better. Put in an overdrive 5 speed. That got me the lower start off ratio and also the lower RMP at cruise but able to drop down a gear and spin it upwhen i wanted to get going.

I would sugest you keep the 411 and put in the overdrive 5 speed?

I finaly got a 2.3L MM rally engine to replace the 1600 and stuck with the 390 and the 5 speed. Now that is a grin!

Have fun

[JackF]

I have a freshly rebuilt 3:91, 25% lsd. I purchased it a while ago from Dave Varco at Aardvark. I paid $895 plus freight. I will sell it for $800 freight paid in the lower 48.

The question was asked if the clutches were replaced and Dave's response was as follows.

"New bearings and seals all the way around. Spool taken apart and inspected for wear. Original clutches reused because they were not worn. Had they been worn I would have replaced them at an additional cost. Unit reassembled and breakaway verified at spec for a 25% LS."

[vinceinIL]

Hi Ben,

My green 2002ti has a 3.90:1 LSD from a 320is in it, and also has a 5spd OD from a 320. I like the 3.90:1 with either a 4 spd or a 5 spd, the OD 5th gear is nice to have for the highway. I would think a 4:11 rear would indeed be a bit too high for today's highway driving, but the 3:64 might also be a bit on the low side, especially for a 1600.

Hope this helps,

vince

[caw901]

Might want to but 4:11 diif. Email me if interested in selling.

Chris