Porsche 356A: Transmission rebuild

[Porscheke]

Hello

As some of you may have noticed.....my car wil go to the painter next month....

So up to the next challenge: REBUILD the TRANSMISSION

No idea on the condition ..... car was not running when I bought it.

So best way is to open the transmission and check everything and replace bearing while i'm there.



Does anyone here have a DIY or a link that can help me with this?

I know that there is a lot of info on the porsche356registry.org website but for some reason I can't acces the "356 project" group anymore?

Grts
Bart

[Phil Planck]

Bart
The factory manual is a must have. I made a tool to measure backlash.
Are you a member of 356 R? If not they recently enacted a new policy preventing non members from much access in hopes they would join.

[Porscheke]

Hi Phil

Yes I 'm a member .....but since a short time 'm not able to access the forum anymore.
Also contact the administrator gives each time an error....don't understand why?

Anyway thanks for the reply

Can you share the tool you made?
Grts
Bart

[roy mawbey]

Bart as Phil advises get the workshop manual or at least the Elfrink book to give you an idea of what is needed. Quite a few special tools quite a difficult job to totally strip down and restore. Maybe check the selection of gears before you start the box may well be in good condition. In my opinion don't just jump in regardless. I think yours is 644 not a 716?

I presume it was full of oil? maybe an engine problem put the car off the road. You can or could buy copies of the manual and the Elfrink book is still available I think on line.

Just get it checked before you get the spanners out.

Roy

[Porscheke]

Hi Roy

You scare me a bit with your feedback
Thought it would be a nice project after all the welding and sanding....on the body

Ok i will check for a manual then

The transmission was filled with oil , but the oil was quite dirty and at the last drops quite vicous

Thougt that clean inside , reseal and put new bearings was going to be a minimum....

Grts
Bart

[Phil Planck]

Bart
Go to page 32 of my Resurection of Foam Car topic for mor details on backlash tool.

[roy mawbey]

Bart I took an hour to read through Phil's page 32 and also looked at page 31. Well worth while reading that. I was a toolmaker for many years so the use of inspection tools is right up my street but if you don't use micrometers dial indicators verniers and the like it will be a challenge to access the transmission and differential and from strip down know exactly what wear you have. Of course you might see damaged teeth, broken parts which will tell you but so difficult if you need like Phil had to determine backlash and need the tool !

It was interesting to read that a first rate guy can probably strip and inspect a gearbox in one day and be able to then to quote for parts needed. To my knowledge and all my receipts going back to 1965 my 716 gearbox has never been apart in around 140,000 miles. Maybe lucky but its serviced my me on time and its a really sweet box. Sure I had a half shaft bearing cage break up on the left side brake drum area which I changed last year but overall I cannot complain.

I just feel its not the easiest job to do if you have never attempted one before. Maybe I am too cautious maybe someone on here will correct me on that!!

Roy

[Porscheke]

So bought the Porsche 356A Service manual

A pity that this is a copy version .... pictures are a little blurry and in black/white

They only talk about the 644 type transmission.

My transmission is a 716 type, don't know the big difference's except the gear ratios's

Grts
Bart

[Porscheke]

Here also some pictures of the numbers on my trans:
Side: 716 301 101 00
Bottom: 49 716/0
Nose cover: 64420 114

[roy mawbey]

Bart, The 716 is almost the same as the 644 but..with an updated design of their synchromesh . The 356A workshop manual is okay for nearly all the jobs on a 356A till 1958 ;1959 and the T2 models of the A version so they printed as supplement manual, showing the updated items including the 716 internals. I don't know if people who supply copies can offer the supplement? The Elfrink book I also have and will check if they cover the 716 in any detail. If you had a real problem on the synchro side I could possibly photocopy a few of the pages from the supplement.

This is why just going in and stripping it down might not be the best way. When you drained the oil from the gearbox the drain nut is magnetic and if the oil was that old it would leave steel debris possible stuck to the bottom of the drain nut. If these were chunks of metal then yes you have a real problem but was it quite clean??

We have over here PR Services who are good on rebuilding 356 gearboxes, Of course realise you are not so close by ! A good inspection of the selectors and the items that connect the gear linkage to the actual gear box needs checking too. A box that does change gear easily is not always a problem withe internals but with the connection linkage.

Roy

[roy mawbey]

Bart, just noticed I wrote above ' A box that does change gear easily ' should read : A box that does NOT change gear easily....

Sorry!
Roy

[Porscheke]

Hi Roy

It would be nice to have the suplement in soft copy
I have the manul in soft and hard copy....but there are no details on the 716 mentioned here (but as you said al is in the supplement perhaps)

Meanwhile I had also contact with Mike Smith from PRServices

Maybe its an option to only disassemble the differential and clean the transmission housing very carefully inside and leave the rest (gearing part) alone.

Maybe swap the 2 differential bearings in the covers (see picture below) while im in there at both sides of the differential and check it (after its mounted back in the car).

Grts
Bart

[roy mawbey]

Bart,

Mike Smith is one person I would trust to work on my gearbox if needed. I have checked the ELFRINK manual and it does detail quite well on the 716 introduced in 1959. I also looked in more detail on the 644 which apart from a small number of items and the new synchromesh is really the same as the 716 version.

I did notice to gain access to the double row ball bearings and remove them is more complicated than you might think, These bearings have a pre-load adjustable by gaskets and to remove the castellated nuts the special tool P37 makes it much easier. Also you would need depth micrometers to determine the preload value and you have to press these bearings out of the plate might even have to heat the plate to 100-110 C to remove. Again the Factory had the special tool. VW 407 for that.

You can be sure to actually watch someone do that job would be invaluable even more so if they had other home made tooling to do it.

Then if it turns out to be the crown wheel and pinion for example all got to be stripped again. I realise the inside has to be clean and its not easy to do without stripping but if the oil was just thick and old I still wonder if the old oil had no metal in it an oil change and then a tryout even just to see if your selectors are able to select each gear easily and oil seals are working okay.

I might be too cautious Bart !! but I still remember the full strip and restoration with my dad on one of his prewar cars and getting the crown wheel mesh perfect with the pinion. Not much fun!

Roy