RedXray

I swapped gears from a 3.42 open carrier to a 4.10 Yukon DuraGrip posi three years ago.

I developed a pinion seal leak and replaced the seal a few months back. I have a solid bushing on the pinion instead of a crush sleeve and during the tightening of the pinion nut (air impact) it went past my scribe mark about 100* degrees. I noticed turning the pinion yoke I had more slop than I did after the gear install. Not sure if it was the extra tightening of the nut or if the slop was already there.

When the transmission downshifts into first gear rolling to a stop I get a clunk I'm guessing from the gear (backlash) slop. Also when cruising in overdrive I'm getting a bucking feel my guess is the rear gear going to the drive side then back to the coast side on the ring & pinion.

Not sure what I should do...

(1) open up the cover and reset (shim) the backlash and pinion preload and try to keep the 4.10 gears.
(2) start a new with replacing the gears with a 3.90 set.

The 4.10 gear set makes manually shifting up from first gear almost useless as you're all over the rev limiter within seconds. I think 3.90's or even 3.73's may be more enjoyable on the street... with a longer manual shift window, more sensible hwy RPM's, fuel mileage, and better smokey burnouts with faster tire spinning speeds.

I already have the gear oil, pinion seal, gasket, yellow marking compound and friction modifier (and all necessary tools). I'd be looking at $275 for a set of Richmond 3.90's and pinion bearings.

Someone please talk me into, or out of a gear change lol

Backlash was on the tight side during the build. Only thing I can think of maybe I didn't have the pinion races seated completely and they moved during the seal repair



Had a good pattern

FFDP

iTrader: (2)

I vote go the 3.90 route.

Bgbldodge

I’d stay with 4.10’s but I prefer my vehicles a touch over geared. For the record my 14 Silverado with stock gears would clunk more often than not as did my charger and does my Durango.

You could try tightening it up but everything I’ve read said once gears are meshed and worn in that’s it and any change will lead to failure. No personal experience with that but wanted to throw it out there.

RedXray

I think with the 3.90 gear set I'll be able to manually use the B&M ratchet shifter without banging off the limiter in 1st. I had 3.90 gears in both my 1968 & 1969 390CID AMX's back n the day. I always thought that gear ratio was just perfect for a street machine. The 68 was an automatic (Borg Warner M12) and the 69 was a 4spd (Super T-10).

I agree those 4.10 probably have some wear issues now.

RedXray

STOP TWISTING MY ARM

Motive 3.90 gear set and pinion bearing kit on the way.

I'm going to use the existing carrier bearings and ring gear bolts



Timken pinion bearing kit

RedXray

Canceled the pinion set and ordered the master install kit with the new ring bolts... it's just money... right lol

3wide

I don't think it will matter what rear ratio you put in there, the ratio and spacing of 1st and 2nd gear in the 4L60 tranny's is not ideal.