First gear selection problem - help!

[Darkhorse]

I'll join this club. I thought I had a problem with the linkages. I've tried double clutching but that doesn't always work either.

[A930Rocket]

billjam

Where did you get the Service Bulletin? Is there a on-line source for them. Or is part of the workshop manual?

Also, does anybody know where to get the Porsche Parts Technical Reference Guide (I think it is)? I have it packed away somewhere, and it's got some good info.

Originally Posted by billjam

I have also found the following service bulletin which may be relevant. My car is an '86 model. Porsche introduced this fix in '87.
Anyone had any experience of this ...

[mark houghton]

Originally Posted by billjam

I have also found the following service bulletin which may be relevant. My car is an '86 model. Porsche introduced this fix in '87.
Anyone had any experience of this ...

Wow, that's good $hit! I forgot to mention that beyond the periodic first gear difficulty, I also find getting into 2nd requires more force than I think it should. Have never "Not" been able to get it in, but depending on the rpms and how warm the tranny is, sometimes I have to pull it in, vs. slipping it in. If I ever decide to crack open the transmission, that's the first place I'll look.

[billjam]

Originally Posted by A930Rocket

billjam

Where did you get the Service Bulletin? Is there a on-line source for them. Or is part of the workshop manual?

I picked this up when I bought a CD copy of the 930 factory manuals and PET a couple of years back.
The service bulletins are in a 562 page PDF file which has a file size of 42MB (= large).
Also on the disk with the 930 manuals were a few other odd files including factory and Bentley Carrera manuals, 68-88 tune-up specs and 84-87 Technical Specs.

I don't recall how I came across the seller of this, but I guess a search for Porsche manuals or PET might find him somewhere (if he's not in gaol ).

[billjam]

Four weeks on I have rectified this problem.
While I had my box apart for new close ratio gears (2nd, 3rd and 4th), I revisited first gear looking for anything out of spec.
It really didn't take much time to identify that the dog teeth were a little worn. Instead of nice sharp edges on the teeth, they were quite rounded. I really should have picked this up last time is was in there.

The good news is that the dog teeth ring is available as a separate part. I've bought them before from Pelican but this time I got it from Albins (here in Aus) for $A153 (about $US120), who also supplied my C/R gear set.

It is a bit of a battle to remove the old ring without the special tool, however I managed it by cutting through most of the ring with a Dremel, then splitting it with a chisel.
Pressing the new one on to the gear takes a fair bit of effort, but again I managed it without any special tools.

Gearchange into first is now much easier. Actually it's not so much that it is easier, it just goes in more often than it did before! The change into first is still quite firm, but now it goes in every time.

This picture shows what to look for. The old dog teeth ring is obviously the one with rounded off teeth.

[mark houghton]

Yepper....them look like some tired dogs to me. Thanks for sharing your resolution to the problem.

[HKZ Bob]

Billjam and Forum,

here some pictures of my dog teeth of the 5th gear and slider.

I am having difficulties to rate them. I have no datum.





How can I rate them. Are they worn out?

BR
Bob

[billjam]

Bob,
I am no gearbox guru, but I can offer a comparison pic between old and new dog teeth rings, albeit for first gear, not 5th.
The 1st gear teeth are not symmetrical - one face is wider than the other but all other gears have symmetrical teeth. However the critical issue is the rounding of the top edge of the teeth. You can see the difference between old and new in the pic below.

Looking at your pictures, the dog teeth look a bit tired but the teeth on the slider look passable to me.
I guess it all depends upon how much of the "while you're in there" budget has been used up. Personally, I'd just replace the dog teeth ring and take a risk on the slider, especially if this for your 72 T. This part is about $800 from our host! Most other models seem to be more like $200.

[HKZ Bob]

Bill thank you for your pictures,

Your dog teeth new looks way different to me than mine.

My ones do not have this nice triangel shape. Do you have a picture of a new dog teeth in the same orientation?

BR
Bob

[billjam]

The best I can do is this shot of a new 930 4th gear.

[HKZ Bob]

Bill you were defining wear on the rounding of the edges.

You said.

However the critical issue is the rounding of the top edge of the teeth

Do you mean the section which I marked in red?

I donīt see much different on your new 4th do teehs to the used one.

See my pictures. Is the right side used?







BR
Bob

[billjam]

Bob, the face you have marked in red isn't the one which is subject to wear.
When the dog teeth are worn, it is the pink edges that get rounded off.