Steve Cattaneo

John,

I have seen that type of failure in all types of differentials many times, the Pinion gears seizes to the pinion shaft ,spiders gears can’t turn, you witness the end result and lack of lube is the culprit. I modified the pinion shaft by grinding four flat spots on the shaft, allowing lube oil to penetrate the pinion gears. I also use synthetic Gear lube. It has better cold /hot lubricating properties.





I am a Quaife dealer, 30 units are the minimum new product runs for a low production car, the cost for each unit about $1,500.00. Mercedes AMG Differentials retail for $1,700 and that doesn’t include installation.

BC

FYI, the NEW old stock kind of shafts that you can get that look like the pic above, HAVE the flats already machined into the sides.

That shaft, as I have mentioned before, looks somewhat "simple" to make, but what would it be made out of to be a bit stronger?

Vilhuer

Didn't factory add oil feed grooves into those shafts in some later version or do I remember wrong?

Garth S

Erkka, I recall you doing some work to retro fit the GTS style gear ( lube) pump to the earlier transmissions. Regardless, would that pump also improve the lubrication to the pinion and spyder gear sets? ..... or is it already in the GT's?

JP Rodkey

If JB Weld works for heads, maybe a few tubes will get your LSD back to as-new condition?

Vilhuer

Stock GTS pump pushes oil into backside of ring gear close to where it meets pinion gear. Pinion must then spread it aroung pretty efficiently in entire differential housing.

Besides oil feed there are also two parts which job is to guide oil directly into bearings. At least one of them is also only used in manual GTS. I haven't looked into automatic GTS diff I have on table enough to know if they can be fitted to it easily or not. Oil trap 1. is only useful when pinion shaft is hollow.

Steve Cattaneo

Vilhuer,

That’s used, #2 = oil trapping funnel catches sprayed oil from # 1, that oil is routed to the Ring gear PINON bearing in manual transmissions, not the spider gear pinion shaft, Different Pinion.

The spider gears pinion shaft strength is not the issue, it’s a lube problem or lack there of.

Don’t know if later years Differentials have that flat spot. I also modify transfer cases and manual transmissions shift rod the same way, only were the rod end slides into the case, if they don’t already have one, for a another reason.

John Veninger

I have the oil trap (part #2) inside my 1989 transmission. I was running an external cooler and redline gear oil.

I just think the diff was worn and just couldn't take the additional punishment.

Here is something from the 1982 service information manual:

Vilhuer

I know, just thought Garth meant this othe pinion. If its possible to install GTS pump into older gearboxes and automatic diffs like I suspect it is, it shouldn't be too difficult to pump some of the oil directly into LSD through rear cover for example. One possible problem is too much lubrication to friction plates. Result could be less than 40% locking.

Knew there was one version which had those grooves.

Steve Cattaneo

That pinion shaft is for an open differential, the LSD units use two different shafts, and they are both notch in the center, a differential is a differential, if you can’t spin the small gear on the shaft, it’s sized, lack of lube to the shaft. I have seen that failure many times in my 40 years as a drive line specialist

John Veninger

Steve,

I'll take a few pictures of the spider gears and shafts on the replacement LSD. Let me know what I should modify to prevent this in the future.

Steve Cattaneo

John,


Send me an E mail when you have them.

Dennis K

That's pretty ugly. My LSD failed but that was due to an experiment to increase the lock. The teeth on the clutches were stripped.

LSD failure doesn't seem too common even w/ high hp cars, so hopefully this is just an isolated case w/ your particular diff. You're on the bleeding edge now, racing a stroker . . . As much as you are a race car driver, you're now the ultimate parts tester too.

BC

What reason is that?

GregBBRD

O.K.

I'm tired of being stupid. I can't stand it anymore and have to ask....sorry.

Every time I look at this thread, I look for the pictures, which are not present. Where did you hide them, John?

This probably will not fix me being stupid, BTW. It's a genetic thing. Blame my mom....I had nothing to do with it.

greg brown