3:08 rear differential question
Pro
Joined: Jul 2005
Posts: 592
Likes: 0
From: ElP TX
I just switched from the 3.08 to a 3.36 for my 76 w/th 350. I just got my trans rebuilt and beefed. I am really hoping I did not go too low with the new rear ratio. I think the 3.36 will be a good choice (for me).
Once all is re installed I shall know.
Once all is re installed I shall know.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
My '72 muncie vert here had a 336 from the factory, and it still is...
even though I ditched the muncie for a 700 auto, some ten years ago, Ifound that 700 was essencially a bad choice with a 336 rear, and had some terminal problems anyway....so went to a 200 4r and it's fine....
I fail to see where a 308 is a good ratio, IF you have a properly behaving/lasting 700 (a very rare case I may add)....you have enough 1st gear to overcome that mild rear ratio...being 3.x first gear, but the drop of 40% engine rpm means you need a broad/flat torque curve to the engine or you fall flat on your ***....
now with the 200 4r having a similar 1st gear to the 400, you will have similar acceleration but then when you go into overdrive and that 308 rear, your engine will be around 2 grand at 70....mine is aroudn 2500 at 80 cruise/locked up.....which if you have any cam at all is about right,
but without that ~.7 overdrive knocking 30% off your engine speed, that 308 puts you into 4 grand region at 80 cruise....
dunno where you live/traffic conditions, but around Wash DC region, can't cruise 80 for more than a minit at most....back into congestion and so slo down....here in Florida, that overdrive is really necessary...i'ts hour after hour cruising 80.....
even though I ditched the muncie for a 700 auto, some ten years ago, Ifound that 700 was essencially a bad choice with a 336 rear, and had some terminal problems anyway....so went to a 200 4r and it's fine....
I fail to see where a 308 is a good ratio, IF you have a properly behaving/lasting 700 (a very rare case I may add)....you have enough 1st gear to overcome that mild rear ratio...being 3.x first gear, but the drop of 40% engine rpm means you need a broad/flat torque curve to the engine or you fall flat on your ***....
now with the 200 4r having a similar 1st gear to the 400, you will have similar acceleration but then when you go into overdrive and that 308 rear, your engine will be around 2 grand at 70....mine is aroudn 2500 at 80 cruise/locked up.....which if you have any cam at all is about right,
but without that ~.7 overdrive knocking 30% off your engine speed, that 308 puts you into 4 grand region at 80 cruise....
dunno where you live/traffic conditions, but around Wash DC region, can't cruise 80 for more than a minit at most....back into congestion and so slo down....here in Florida, that overdrive is really necessary...i'ts hour after hour cruising 80.....
Safety Car
Joined: Feb 2006
Posts: 4,855
Likes: 2
From: Columbia South Carolina
Pardon the inturruption but when comparing Rear diff and RPM between cars you must factor in tire diameter, the 235/60s I have wont produce the same RPM reading as eh 225/70s My neighbor has in his even with all else being the same. Just my .02
Racer
Joined: Nov 2006
Posts: 399
Likes: 52
From: Louisville Kentucky
