Here's an odd one. I took apart the 722.4 trans in my 1988 190D to track down why it won't shift into fourth gear. I found the reason, a failed Teflon o-ring on the K2 clutch support stub, which was allowing oil pressure to bleed off instead of engaging the clutch. The weird part is what i found in the front planetary. Assuming the pic I attached comes through, it shows the bushing that's installed in the sun gear of the front planetary. It's damaged, and i can't for the life of me figure out how or from what. It almost looks like it was damaged on installation, with hints of punch marks on the back (hidden in the image) edge. What i also don't understand is what this bushing actually does. The input shaft passes through, but the bushing doesn't appear to actually support the shaft in any way. Has anyone been inside one of these to the point of understanding all their details?
Richard
Here's an odd one. I took apart the 722.4 trans in my 1988 190D to track down why it won't shift into fourth gear. I found the reason, a failed Teflon o-ring on the K2 clutch support stub, which was allowing oil pressure to bleed off instead of engaging the clutch. The weird part is what i found in the front planetary. Assuming the pic I attached comes through, it shows the bushing that's installed in the sun gear of the front planetary. It's damaged, and i can't for the life of me figure out how or from what. It almost looks like it was damaged on installation, with hints of punch marks on the back (hidden in the image) edge. What i also don't understand is what this bushing actually does. The input shaft passes through, but the bushing doesn't appear to actually support the shaft in any way. Has anyone been inside one of these to the point of understanding all their details?
Richard
I don't know the answer, but send me PM with your email, and i would be happy to send you two sets of MB trans manuals (.pdf). Michael
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Michael
1986 190D, 5 Speed
1985 Porsche 928, 5 Speed (32v)
1980 Porsche 928, 5 Speed (16v)
So Cal
I believe I've discovered the cause of the damage. The car is basically new to me, and clearly someone's been inside the tranny before as it's apparently missing an axial thrust bearing, thrust washer and washer that go into the clutch drum and provide surface for the snout on the front pump. That explains the damage. Too bad, i was hoping to rebuild it but now i think it's time to find a replacement. Anyone got a good source on MB auto trans, or better yet a 5-speed manual for conversion?
The pics show, in order (assuming they load as I wanted them to): Front clutch drum as it should be, with washers and axial bearing before installation; front clutch drum with washers and bearing installed; my drum as it came out with no washers or bearing; damaged snout on my front oil pump. Thanks to Marc for the pics of stock drum with correct parts.
Richard
I believe I've discovered the cause of the damage. The car is basically new to me, and clearly someone's been inside the tranny before as it's apparently missing an axial thrust bearing, thrust washer and washer that go into the clutch drum and provide surface for the snout on the front pump. That explains the damage. Too bad, i was hoping to rebuild it but now i think it's time to find a replacement. Anyone got a good source on MB auto trans, or better yet a 5-speed manual for conversion?
The pics show, in order (assuming they load as I wanted them to): Front clutch drum as it should be, with washers and axial bearing before installation; front clutch drum with washers and bearing installed; my drum as it came out with no washers or bearing; damaged snout on my front oil pump. Thanks to Marc for the pics of stock drum with correct parts.
Richard
There are tons of warrantied auto boxes on eBay motors. I bought a good used one from landautodismantling for $400 bucks that shifted great before my C class burnt to the ground.
Murphus: Sorry about your luck, but I'm curious. Do you work on cars for a living, because I was impressed by how quickly you had your transmission stripped down!
That's a great offer Metafly! However, I'll need more than the washers and the axial bearing. I'll also need the front pump and the front clutch drum as they're both damaged from the experience. And then I have to wonder how much metal is in the torque converter. Possibly very little, and possibly in a very fine state as it would have been mostly ground up, but... And no, to answer someone else's question, I'm not an auto mechanic, just stupid enough to not appreciate my limitations!
Richard
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