915 gearbox - circlips?

[peter915]

Hi ya's,
Can anybody tell me how you get the second "circlip" out of it's housing? They are holding the bearing in place.
I have already got the first one out - each bearing has 2x holding it in place.
See Photos:




Thanks
Peter

[Geo9146GT]

What,exactly, are you trying to do?

[peter915]

I'm replacing the bearings on my 915 gearbox, plus syncro's on 2nd and dog gear.
Circlips are doubled - one behind the other, but not like a standard circlip.

[Geo9146GT]

Why don't you remove the intermediate case from the rest of the transmission first, then remove the outer bearing races from the intermediate case - you should be able to get them out using a
drift and hammer if you already have one of the retaining circlips out.

[peter915]

Yes, I plan to open the intermediate case, but I am assuming the "circlip's" retain the bearing shell in the cavity of the wall between gearbox & front nose section. The circlips have a diagonal cut in their ends. The clips fit into a rebate behind the bearing - I assume to prevent same from moving out of the housing?

[mackskibum]

You are looking too hard at this. The circlip just retains the race in the housing. Separate the intermediate housing and the shafts will remain with the differential housing. You should then be able to get the race out with a drift as mentioned above. On my 915, there was only one clip on each bearing race.

Was this case apart before? Did a previous repair require the use of two clips?

Your photo shows a clip still in place- is that the second one? It almost looks like they are jammed in next to the race for some reason- that doesn't look right.

[MBEngineering]

HI take the center case of the diff case and change the bearings, if you have any prob's ring me , 015395 67959 workshop, 07885 622051 mob, i am just across the water, i can fax you the parts of the manual if you like.

regards mike

[peter915]

Hi ya Mike & Dave,
Yes, there is 2x clips behind each bearing. The first one came out easy, through the gap/slot at the side of each bearing.
As I said, I am going to split the case - this weekend I hope.
Whilst you guys are on - do either of you know how to pre-load the pinion/crown - I plan on replacing the bearing on the pinion, so the shim setting will change?
Can you use plast-a-guage for this -between the pinion & crown teeth?
Mike - I will phone you or see if a text message will work?
How are you going to feed the manual through the fax machine?
Thanks guys.
Peter
Ps my email should be on the email icon.

[MBEngineering]

HI i have the diff seting tools and all the shims if you would like a trip over the water, i am about 45Min from Heysham up the M6 at J36. got your TEX

regards mike

[mackskibum]

The pinion pre-load is a touch subject- do a search on pinion bearing replacement. There are many opinions on the subject from different sources. Read some posts by Grady Clay for the official procedure. I replaced mine using the shims in the same positions that were removed originally. The pinion bearing race is held in place the same way as the bearings in the above photos. If you haven't had a 915 apart, it will make sense once you are there. The carrier bearing pre-load is another issue, and this can get complex. If you can access the tools and follow Grady's instructions you should be in good shape!

Good Luck!

Dave

[MBEngineering]

HI mackskibum your manuals/gearbox's are different in the USA on a 915 box , as all the box's i have taken apart i have never seen any circlips holding the pinion bearing in, and is my posting above your, not coming up on your computer, but thinking about it you prob' will not be reading this one, back on the gearbox job PETER is any of the bearing outer races loose in the cases, and please do not take the selector fork bolts out. will ring you later today

regards mike

[mackskibum]

MB- you are correct- the pinion race is pressed in- I had something confused in my mind. Thanks for the correction. It sounds like Peter is in good hands.

[MBEngineering]

HI not a prob' as i was beginning to thinking now-one was reading the posts i put up

regards mike

[peter915]

Mike,
I have tried sending a email via this forum and your own website.
Peter

[MBEngineering]

HI thay both work, got them, try'd the site and thay won't let me on

regards mike

[MBEngineering]

HI just to let you know the box has been repaired, Friday afternoon/night, so peter could catch the ferry back,at 2.30 in the morning, don't under estimate the problem you have with the gear box, when assessing what to get before you strip to repair what you think is wrong, peters box had 2nd gear sincro prob and bearing noise, parts where orded to repair the box through PELICAN PARTS no prob, when the box was fully striped a small can of worms was opened up and at app 5ish in the afternoon more parts where required, as 14 teeth missing from st gear dog (hence the bearing noise) so a trip 1hr north to pick up parts had to be dun, while peter was getting the parts the in put shaft was striped, 3rd gear dog also was U/S, so a phone call and a dog ring and slider was also picked up, ever thing now going back together OK , so set the diff up!! checked the pinion depth and it was way out, that far out the manual limit was max of 0.50 and this was 0.75, now we striped the pinion shaft and checked the new bearings, both correct size, rechecked the settings on the tool, both OK then checked the shims that came out of the box 4 shims 0.20, 0.20, 0.20, 0.15 from the factory, back in with a new set of shims and we were back in business, pinion set , diff bearing pre' load OK set the back lash and pop the box back together, the oil pump was a challenge getting the outer case just right so the gears will tum round, once sorted and fitted to the box, the gear selection checked , pop it in the back of the car and head for the 2.15 ferry to fit the box on Sat.
just a up date on what has been done, poss peter will post some of the photos he took of the build later.

regards mike

[peter915]

Once I finally found Mike's workshop, work started on the gearbox.
What I thought was a fairly simple repair turned into more than that.
First off, the speedo sensor pocket, in the side of the casing had ruptured through into the diff. See Photo.

The list of new parts I had with me included second gear syncro band and dog gear. But on inspection of the gear-stack, 1st dog gear was all-but destroyed, with something like 16 teeth missing.
3rd gear dog was also badly worn.
Like Mike said, it was probably the broken teeth lying in the bottom of the box, which sometimes may make a gearchange difficult -the pieces of metal stop the shift lever moving properly.
Once all these parts were install on the gearstack, it was time to set the pinion & diff.
This was the Black-magic part.






The dial gauge is set to a depth from the info inscribed on the crown wheel. Not a real clear photo.

This is then postioned onto the end of the pinion to determine how far the pinion is in or out of the diff housing. Shims are used to move this forward or back. My pinion had four shims behind it and the manual says that 3 is the maximium allowed. Plus, the total thickness allowed is .5mm -mine was .75mm from the factory.
If I had had more time this could have been fixed properly by having the pinion machined down by say .4mm. But as it was 10.00pm on a friday night, it was a case of "Oh Well" and put it back together as it was.
Then crown and pinion lash was then checked.



This part see's the 2x axle carrier bearings come off the diff many times -as each attempt is made to get the crown wheel sitting up to the pinion with the right amount of lash -play between the teeth. Spacers are used behind these bearings to lift or drop the crown wheel. I think this took about 6 or 7 attempts before Mike said it was OK.
By 12.30am, Saturday morning, we were bolting the oil cooler back on, and at 12.55am I left Mikes place to go and catch the Ferry at Heysham (boarding at 1.45am)
A big thanks to Paul who help with the extra parts.
http://www.porschesparesdirect.com
And of course a huge "thank you" to Mike Bainbridge at MB engineering
http://www.mbporsche-engineering.co.uk