I'm looking to switch from the 4.56 gears I have in my Moser Dana 60 to a 4.30 ... I think .
It's a street/strip 76 Dart Sport weighing 3200, 455cid small blk, 727 with trans brake, 30" slick and has run a best of 9.76 @ 137 open exhaust ... shift light is at 7200 so shift probably occurs at 7400 and the light is on at the 1000' mark so I'm crossing the stripe at 7400+

Peak HP/TQ throught the mufflers from the chassis Dyno was 585 at 6750 and then drops to 573 and holds there till 7200 (end of run) Peak TQ was 482 at 6350

Am I over geared ??? I'm thinking a 4.30 would bring it down to the 7000 ish mark and I might pick up some et/mph
Any thoughts ?

4.56 is steep for that size engine and 30" tire.

I am running 4.88's but I am running a 32" tire and I am trapping about 74-7500

other than a little less trap RPM what else do you think it would change?

Life expectancy and possibly a little ET

well I will just leave it for now we only get to run a few races a year that are 1/4 95% of every thing down here is 1/8 so I don't spin it that high very often.

Years ago, there was a guy back home who had a Dana 60 in his
455/4-speed Trans Am. It had 4.88s (I don't remember tire size).
Anyway, he used to run it at Kanawha Valley (1/8 mile) I told
him it would probably be quicker with 4.10s. He switched to
4.10s and it was quicker. I don't remember how much but, I
know his car was NOT light. True story.

Thanks for the info so far !!

So are we talking 4.30's or ... lower to 4.10's ?

If it's 4.30 ... who makes a good gear ? Richmond does not seem to make them in 4.30 ?

Dr. Diff has light weight 4.30's.

Unless you can get a 32-33" tire under the car, I'd say 4.10

Ok, 4.10 is easier to find so that's good.... Now, should I be looking at a pro-gear ??? It's a street gear in there now and it seems to be doing allright. I do street drive mine "a little" , just cruising to the car show or car wash... but I obviously don't want to break anything !!

You don't want to run a Pro Gear on the street. The street
gear is harder and work in 98% of drag applications.

2nd that.

Make sure you get the correct series of gear, that 4.56 should be a series 4 and the 4.10 MAY be a series 3. The 4.30 could be either or

Joe

All pro gears regardless of ratio, all 4.56-7.17 street gears and Richmond 4.10 street gears fit 5 series carriers.

All other 3.54-4.30 street gears fit 3 series carriers.

.... so is there a way of telling what series my Moser Dana 60 is? Or better yet ... Will a Richmond 6900521 4.10 set fit it ??
thanks everyone !!!

Once again, all 4.56-7.17 gears fit a 5 series carrier.

Richmond 4.10 street gears also fit a 5 series carrier.

Sounds like you have a 5 series carrier. I doubt Moser used a ring gear spacer and a 3 series carrier to install your 4.56 gears.

THANKS to all !!!!!!!!