I run a NON lock-up A518 (46RH) in my '93 W250. During recent repairs, I've found the overdrive planet gears present with substantial galling of the crown and face of the teeth, along with some pitting close to the roots of others (Sun/Annulus-gears as well). There's manually detectable slop in the pinion shafts.
This episode of repairs was brought on by a popped intermediate shaft. It broke clean in the root of one side of the groove where the spacer ring goes behind the transmission's rear planet. Those splines of the intermediate shaft just before engaging the OD planet carrier were twisted. I figure the slop in the OD planet assembly allowed things to bind just enough to . . . .

Time to replace the assembly (typical 240,000 mile wear).

The stock/OEM overdrive planetary in my heap is a 5-pinion (straight-cut teeth) with a steel carrier. It appears exact replacements are being made of unobtainium and are in short supply.

I'm being told that while the later planets running angle-cut teeth are quieter than those with straight-cut teeth, the angled teeth, may not be as strong. At least, the straight-cut teeth are more desirable strength-wise.


-> With perhaps an absolute maximum power of 500hp / 900ft/lbs to the ground, am I risking a weak link there by going to the angle-cut unit? While my mess is no "Big-Dawg", I do launch it hard with perhaps 20psig of boost just before the light goes green (a 60' of 1.8 average @ 6400lbs).

Assuming the straight-cut unit is NLA, it appears my first options might be the standard off-the-shelf retro-fit kits for the 47/48s. It looks like 5 & 6-pinion upgrade kits are available.

I have no experience as to what folks are doing with the 47s & 48s to beef the OD section, if anything, so please pardon my ignorance.

I see that 15 & 22 degree teeth are available. Is there a preference of one over the other?

Thanks folks.

 

David call Rick at A&A I bet he has them in stock and if nothing else he can and will answer your question. tell him the guy that bought the billet input for the diesel 727 sent you.

Bobby

 

Thanks for the reply Bobby.

I'm being told that Dave (w/Goerends) says to don't even think about the 22* stuff. Otherwise, it seems the 48 owners are going to the 15* 6-pinion type.

If I were to pursue the straight-cut unit, I'll also have to obtain a new Annulus and Sun gear as well ($). Mine are pretty-much toast like the planets.

As a final nail in the coffin if you will, the 6-pinion, 15* retro-fit kits (Annulus, Sun and Planetary) are around $150.

 

David what you come up with?

 

Bobby,

I ended-up going with the newer 15*, 6-pinion, steel carrier overdrive planetary gear-train . . .





I've since moved on to the 3-speed transmission section and upgraded the front and rear gear-sets to 6-pinion, steel carriers.





I've increased the clutch-steel counts in all the clutch-packs and have just completed moving things around so as to ensure full spline engagement on the rear pack (it was a problem area) . . .





Over the last couple of days (in between service-calls ), I've managed to replace a few well worn bushings . .





I'm trying to complete reassembly of the main-case this weekend and hopefully get the valvebody back in.

Then I've got to reseal/new bearings in the transfer case.

 

Looking good man! I'm glad you can figure out the auto tranny... I don't even DARE digging into mine.