My 1968 2+2 runs about 4000 rpm at 65 mph. I think the differential
ratio is 3.54 to 1 if I recall correctly. I would like to get something closer to 3 to 1 if possible. What all years-models differentials will work
in my car? Would it be better to replace the whole cage? (differential, axles, hubs, etc.) I've heard that axle flanges are not all the same through
the years.
Flowerchild

Submitted by SE98-32482CJ on Wed, 06/29/2005 - 17:40

Ross you can switch gears but your tach is off. For a 3.54 rear in an "E" 4000 is 85 MPH. The P4000s are very close to correct size (although way too wide and rubbing). If you get a 3rd member from a salvage yard you will have to go through it. I think you need to fix the tach (or what ever is wrong first). George Camp

Submitted by rwglandt@hotmail.com on Wed, 06/29/2005 - 17:08

George, Sorry I didn't reply, I've been out of town. The tires are Pirelli P4000's, size 205/70 R15 95 V. The clutch is fresh, (no slippage)
and the tach doesn't seem too far out of whack from the sound of the revs.
Can taller gears be put into my same housing? Or would it be cheaper/easier to get a whole different pumpkin from a salvage yard? Flowerchild

Submitted by SE98-32482CJ on Wed, 06/01/2005 - 21:01

On second thought I did some quick math and you can't be running tires small enough to cause the error. You are either going faster than you think (speedo related error) or your engine is not running at 4000rpms(tach error). If you had a clutch problem you would have burned it out. Do you by any chance have an automatic? If so 4000 would be about for a model 12 that is not shifting into direct drive. George Camp

Submitted by SE98-32482CJ on Wed, 06/01/2005 - 17:20

You did not say what size tires you are running but you should be at about 85 MPH. Gear ratios are available for many ratios but you need to keep your cage. First I suggest you fix your tach / clutch/ transmission. George Camp