Transmission/rear-diff rebuild & replacement by reputable local shop questions
 

I recently took my 915 in because I was getting a whirring/light friction noise accelerating through 1-2 gear, also at times absolute grinding without being able to shift into any gear, and extremely gummed 5th gear/hard to get in or out.

I decided to run it into a place to get it analyzed, then took it in immediately to a local reputable Porsche mechanic. Originally quoted about 10-15 days to completion, with a little extra replacement and cleanup around the engine bay~for example: all new hoses and oil lines/few gaskets...of course this pushed the completion date back to what came out to be around 1 month.

First of all, i hear this is normal with these older models to take time to receive parts/correct parts on order and whatever.

Next, when I get the car back I notice it’s leaking gear oil and so does my mechanic so he calls me back in to tell me I need a new rear differential giving me options to get a good used for a lot less or upgrade to lsd~so I’m interested and tell him to install lsd...I’m thinking this should take about a week to complete and I’m also wondering why the rear differential is leaking now since it was never a problem to begin with. I’m also thinking since he also told me a used Speedo ring magnet slipped out in the trans~is this going to diminish any work just done in there.

Well, it’s been another 3-1/2 weeks waiting for the rear differential to be installed and I think he’s replaced the axle shafts as well, as I was shown loosened up and down movement in them that apparently a new diff didn’t fix.

Anyone have experience in this?

The cost was of course outrageous and I’m now interested in selling to upgrade to a 2006 or 2007 C4-C4S because I don’t want to drive with an already thrashed interior anymore and I don’t want a money pit if this is what it’s going to become.

What does a leaking transmission have to do with a differential? Where was it leaking? was it leaking when you brought it in?

I was a victim of this BS 30 years ago when leaking trans led to new clutch and throw out bearing. Cost me way more $$$ that I had at the time. In the end the leak was fixed but my throw out bearing was very noisy.

You are what is termed a money tree. Everything you described could be from a multitude of sources. Whirring/light friction noises could be just about anything, not being a transmission guy, it might be your inexperience with the trans. "absolute grinding without being able to shift into any gear, and extremely gummed 5th gear/hard to get in or out" could be something as easy as a clutch misadjustment. the likelyhood of every synchro being bad at the same time is highly unlikely. The inability to shift could also be something as simple as the shift coupler. He had the trans apart and didn't tell you your "differential" was bad. You are being ripped off.

I agree with above, there's a real good chance you are being taken for a ride. If it wasn't leaking before service, and then is leaking after service, the root cause is not a broken differential. It wasn't put back together properly.

Also sounds like the actual original problems were never properly diagnosed, so they're just throwing whatever they feel like at the car because you keep opening your wallet for them to dig back in.

Proper diagnosis:
- Some whine in a 915 is normal. If the whine has changed, is it in only certain gears, or all? Does it change pitch according to speed or engine rpm? Does it whine under acceleration, coast, or both?

Answering these questions correctly would greatly narrow down the whine issue. There's even a chance that a simple trans fluid refresh would quiet the whine.

For the grind:
Did this happen when the car was cold, hot, or both? Was it all gears equally? Could be a mis-adjusted clutch not fully disengaging. Could be a shift coupler that's become worn or out of alignment. Or could again just need a fluid freshening.

I'm not saying you definitely didn't need major service, just sounds like the right process wasn't followed. And things seem to be being tacked on after the fact to boot. Do you have an itemized invoice you could share? Plenty of people here have refreshed their 915 and can fact check.

Did Motor Meister relocate to Utah?

Your 915 is a transaxle - transmission and differential gears are all in the same case.

I would think that a single "service" of a 915 would address all of the issues - gearing, differential, seals - the whole bit. It certainly should not have been leaking after it was serviced.

Regarding the other hoses and things they replaced while they were in there and the schedule delays - it's hard to say over the internet whether any of that was legitimate.

There are plenty of shops out there who will do a fine job of overhauling a 915 for a quoted price and schedule, with any added costs itemized. This outfit sounds like they don't know what they are doing, or they are taking you for the ride.

Holy moly, You....are.....being.....ripped.....off!!!!!!

Not a leaking trans, a leaking diff after all of it

They opened up the box and it's leaking from the seams (I presume). Sounds like a warranty job to me. Instead you got the upsell to a new differential. If I were you, I will speak to them about their warranty terms and if they refuse to work with you, go to the state automotive bureau.


Yes, the last local mechanic I went to for a low speed "jerky" CIS issue said my axles were bad, too much play. I redid the entire system myself and guess what, no more "jerk".

Just having the vent "cap" on the top of the transmission oriented the wrong way will allow the gear oil to get sucked out of it and all over the place making a huge mess. I'd rule that out first.

I hope you paid with a credit card. Find a new shop. Fast.