BC847
New member
- Joined
- May 14, 2006
- Messages
- 851
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.
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.