Bertrand Daoust

First, I would make sure all cables at the quadrant are well adjusted.

See post #1 here.
https://rennlist.com/forums/928-foru...justments.html

The last one to be adjusted is the transmission cable.
If this one is too slack, the up-shifts will be way to fast, and the down-shifts way too late.

Like Wally wrote in his post, "the cable adjusts shift speed, the modulator adjusts shift firmness".

x98boardwell

Bertrand, yes all have been adjusted correctly once cables were replaced when engine was put back in car. The quick shifts I was referring to was with bowden cable disconnected during diagnostic testing.

Bertrand Daoust

Have you tried to tighten the transmission (Bowden) cable to see if it helps?

If the cable is too loose, it will up-shift very rapidly.
From 2 to 4 quite rapidly.

Worth a try maybe.

Like already said, the first gear start all the time is not normal BTW.

x98boardwell

Bertrand, yes I have but that would only affect shifts, not a gear slipping. Which is also why I think it's starting in first as 2nd can't be selected from a stop as it's "not available" or that the transmission doesn't see it as an option. I'm no expert so I'm assuming the trans would select the next best gear but who knows..

Trans was rebuilt by All Valley in Clovis CA. Reverse gear wouldn't engage with previous owner so they rebuilt it at that time in 2011. I had thought it was in 2009 but apparently was later.

GregBBRD

The only "external" modification that can be done to force the car to start in 1st gear is for the electrical kickdown switch wires to be jumpered (or the relay to be jumpered.)

I would start there and verify that this has not been done, or if it has been done, "undo" this and make sure that the kickdown switch works properly and you can hear the kickdown solenoid engage, when the kickdown switch is activated, at WOT.

Determining this, defines your next step.

If the kickdown solenoid isn't jumpered, the problem has to be inside the transmission and you are very likely to need "professional" assistance.

If the kickdown solenoid is jumpered, so that it is engaged all the time, undoing this and then testing the car would be very informative.

By "starting" here, you will be able to very quickly determine if your particular problem is external or internal.

If internal, I'd personally start with the valve body and see if the problem lies there. The GTS valve body is very different, as Porsche eliminated the secondary oil pump inside the transmission, which required changes to the valve body. Any "Mercedes only" transmission specialist isn't going to know or understand these modifications, nor are these changes "detailed" anywhere in print (that I'm aware of.) You are going to have to utilize a resource that is extremely familiar with these valve bodies to correct the assembly error/errors, or buy a replacement valve body, directly from Porsche. (Good luck with that...the valve body is Porsche GTS specific and has been NLA for years.)

polecat702

Bryan, Greg Brown, is the world authority on these cars! His advice is the Gospel!!! When I get time my car's original transmission will go to Greg for a complete rebuild. He is the only person I would let touch it. It'll be better than factory new!

x98boardwell

Thanks Greg. Car has had 1 owner (except the collector who drove it 800 miles in 10 years) and all maintenance was performed at Hollywood Porsche which i have. Only issue was mentioned above not going into reverse so it was rebuilt. He did not know where to take it that is why it ended up at a local German shop who outsourced. I doubt the kick down has been modified but I will check to be sure.

After that you had mentioned the valve body would be a start... would this be something that you would prefer car with or could I just bring trans to you?

Thanks,
Bryan

GregBBRD

If the kickdown isn't jumpered, the valve body has to be funky...there's no other way that I'm aware of, to have the car start in 1st gear.

If the problem is only there, it might be worth the effort to just send me the valve body, to go through.

It's easy to remove and re-install, especially with your skills.

However, I'm a bit perplexed at the slip in 2nd gear. I've been trying to figure out how that can occur from a valve body issue. I'll need to ponder on that, a bit.

x98boardwell

Greg, do you think it's worth sending valve body or should I yank entire trans out and bring down due to 2nd gear issue? I'm also perplexed how its slipping in 2nd. I can call this week to discuss as well if that would help.

Thanks, Bryan

GregBBRD

Regardless if there are internal transmission problems, the valve body is going to need to be disassembled, inspected, cleaned, and properly re-assembled.

Hope for the best and do the valve body 1st. If that fixes it, great. If not, a bit of your labor (taking the valve body in and out) and some fluid is lost.

andy-gts

could the clutch packs be worn and just shift 1,2,to 3rd really quickly......

GregBBRD

I'm assuming that even a "hack" rebuild (not very many miles ago) would consist of new clutch packs...

x98boardwell

Removed the cover to gain access to valve body. Check out the debris in the pan, very fine particles.

Bertrand Daoust

Ouch!

polecat702

Bryan, a word to the wise. Greg Brown, is the best there is, stop beating you're head against the wall and give Greg the Transmission. It will be better than new, ( cause Greg knows all the tricks to get the most out of one) and have him rebuild yours!!!! It's not that big a deal to pull the tranny. Dean Fuller, has a great video tutorial in the RL archives!