Look between the jaws of the wife's vise..... :eek:

I had mine in for a around 2500 miles when I needed to drop the engine again and there was what looked like corrosion on mine. The shaft looked slightly polished and felt uneven. If these are oilite bushings then I may have caused the problems with a very light coat of white lithium grease to lube. Anyone know if these are oilite bushings?
I rotated the shaft 180 for a new surface contact area.
http://forums.pelicanparts.com/uploa...1266381440.jpg

http://forums.pelicanparts.com/uploa...1266381676.jpg

$175 is pretty steep for a total of 2 bearing journals @ 20 mm length of hard chrome on the shaft. Have you thought of farming the job to a Los Angeles shop and quit working with the clowns in San Jose? This is a tough economy we're in, and there should be plenty of job shops who could quickly and accurately get the job done. Of course maybe the small job shops have since gone under with the failing economy. I would certainly shop the job.:eek:

Some more info.
There is only one company making these kits, they are sold to companies(resellers) like PP and others.

There was mention by a reseller that the bushing material was Oilite. I calle Oilite and there are several ways to determine if it is or a "copy" of Oilite. There are also Oilite type bushings made that are not originally supplied by Beemer Precision. Put the bushing on a clean piece of paper and if the paper absorbs oil, then there is oil in the bushing and it is an Oilite type materail. You can also look under a microscope and see the "holes" between the powder balls making up the bushing material.
I found out the "original" website making these kits and there is no mention of Oilite or Oilite type material. All that is mentioned is bronze bushing. There is mention of putting grease on to assist with shaft installation, this is a no-no with Oilite. I looked with some magnification and didn't see any sign of "holes". Given these two pieces of info., I'm about 90+% sure the bushing material is not Oilite or an Oilite copy.

The reseller has offered to sell me another kit at close to retail or 2 bushings.

Right now I think I have a number of choices:

1- get a complete new kit and install (no real engineering improvement)
2- get the shaft hardened and install new bushings from reseller - install with a bit of grease
3- get the shaft hardened and get bushings made from Oilite material - install with a few drops of oil
4- get the shaft hardened and get or make bushings from plastic bushing material e.g. igus iglide self lubricating bearings - there are a number of types under iglide
5- get fed up and install the parts I have an sell the car (not a good option)

Yes, I could shop the hard chroming around and get a better price by e.g. $50 and spend $50 of crapping around with shipping/etc. Considering the time delay/etc. $50 is not a priority. This is the price I pay for not living in LA.

IMHO - this kit doesn't appear to me to have much in the way of complete and thorough mechanical engineering and testing. Appears to be made from run of the mill unhardened steel and e.g. 660 bronze bushing materials. The website doesn't have this detail.

Any comments? If I order igus bushings does anybody want some? It looks like igus has standard flange part numbers with 16mm ID and 22mm OD.

Thanks.

While this seems very boring to many, having the fork wear to a point of high friction and then having the "tabs" break off on the trans housing will not be boring if it happens to you.

Why not go back to the original Porsche design parts that lasted 15 years? In the end, isn't that long enough between clutch replacements? If you didn't bore out the case, seems like the original needle bearings still ought to fit ... or am I missing something?

Henry - you don't need to harden the shaft if you get oilite bushings.
JB

my understanding is that the "original" sized needle bearing setup not requiring boring the ears, is no longer available... I could be wrong but I'm pretty sure this is what the reseller told me... I asked. I don't want to take material out of the ears.

Jim, both simple bronze and Oilite type probably work better with a hardened shaft. I have that question into Igus.

I was only trying to save you some $$! A hardened shaft AND oilite is the best option, but may be a bit of overkill. Hardened shaft, old bushings OR normal shaft and oilite bushings can reasonably be expected to do the job.

JB

I'd be surprised if Porsche used a custom sized bearing. Normally, bearings are always standard sizes. They may not be available from Porsche, but I would expect an online bearing supplier to have them ... and needle bearings are usually cheap!

This matches the dimensions from your drawing (16ID, 22OD, 16 width):
NEEDLE ROLLER BEARINGS | Shell-Type - Open End, Metric

http://forums.pelicanparts.com/uploa...1266576610.jpg

Not to muddy these already turgid waters, but---- if this were mine and I felt semi-fanatical about doing it right I'd consider the following. First forget needle bearings; they're a lousy choice for short reciprocal applications like this. A smooth shaft in oilite bushings will last a long time. I believe the shaft is just a shaft with a few holes in it so go to Berg or Stock Drive Products where you can probably buy a hardened ground shaft of the proper diameter (look in the metric section) and oilite bushings to suit. Have a local machine shop drill the appropriate holes and if necessary turn the OD of the bushings to suit. arrange a couple of felt washers to keep clutch dust out; maybe make small collers with set screws to hold them in place.
assemble the whole thing and put a drop of heavy oil on outer end of both bushings whenever you do regular maintenance. Alternatively, buy a new shaft from Porsche and do the rest or have your shaft plated and ground. The cost of these options will vary but a little research should yield the best one.
regards,
Phil

Phil and Burgerm. - Thanks for the efforts and interest...

Burgerm. - good finding the needle bearing that works - that is an excellent solution, the only reservation I have is that over some time the clutch dust gets in there and binds up the needles, this is what I saw when I took out the original needles 5 years ago.

Phil - agreed re. needle bearings as mentioned above - to get to a new shaft I think the shortest path is to get my worn shaft repaired and hard chrome applied. This will cost about $175. Re. Oilite - the "new" kit is supposed to include "Oilite" bushings and I can get just those at a nominal cost.

I'm currently trading emails with two different people at igus and they are sending samples of plastic flange bushings that fit made from two different materials, one better for higher temperature compared to the other. I'm still in the process of confirming the force and temperature. Any ideas on that?

Here are the two pn's I'm working at igus.
Model 1 - GFM 1622-12 - 12mm long, would like ~17mm
Model 2 - JFM-1622-20 - a bit long, flange a bit thick - could be cut down if needed

If I have the force needed to pull the throw out bearing I can calculate the force that would be applied to each bushing. Needed to assist with selecting plastic material type

Also need a typical and "max" temperature - this helps with selection of plastic material.

Right now I think I'm down to 2 choices:

1- repair/harden the shaft and install new "Oilite" bushings - lubrication approach needs discussion - oil attracts debris - no oil or grease causes wear

2- repair/harden the shaft and install plastic igus bushings - designed to operate without lubrication for life of bearing - risk is that this is new territory

Does this sound like where I'm at? If there was a way to seal needle bearings I would consider that.

Thanks.

added comment - I don't think there is an easy way to get felt seals or other types of sealing installed... the transmission needs to be almost installed before the shaft can be slid in. Right? maybe there is a way to get this all assembled where I can get at it. If this is the case then yes adding sealing would be the way to go and then could consider the needle bearings.

a bit more new info.

I tried a few tests by pulling on the throw out bearing to see how much it took to start the diaphram bending...

1st I hooked up some ropes and put them around my waist and lifted with my legs... nothin moved... so I figure that was easily 400 lbs.

2nd I made a lever system and estimated the forces to start it moving and got 650pounds for force or 325 pounds per bushing.

quick force estimator..

http://forums.pelicanparts.com/uploa...1266699648.jpg


for reference here is the arm/etc. asm. - the "tabs" or "ears" holding the shaft are what you don't want to break - let's say really don't want to break.

http://forums.pelicanparts.com/uploa...1266699698.jpg

OK, you should have posted pictures of you doing this.... :eek:

In today's world, they have a service called mail, or shipping. If you call the price you were quoted in San Jose, shopping; then I would imagine you will most likely settle on something less than an optimal fix.
I'm from a world of fix it once, and forget it. This is not to say I have never had to redo a job I may have hamfisted. But I guarantee I only did it once.;)
Now "shop" getting the shaft hard chromed in the bearing areas + a little extra to extend beyond the bushings, install Oilite bushings with approx .001 - .0013 clearance fit, and be done with it.
Project simple fix

Nine9six and others:

Re. the Igus plastic bushings - I'm now having second thoughts - it will be somewhat risky to get the final clearance wanted. The bore on the fork needs to be enlarged somewhat - per the Igus data it is under the min. for the available bushings - = too much of an interference. If I enlarge the fork if, in the future, I have to use e.g. bronze bushings there may not be enough press fit.

The fork has an interesting geometry - the force from the slave cylinder is at the edge or outside the two bushings - I think this means if there is too much clearance one ear on the throw out bearing will get much more pull than the other ear. Having too much bushing to shaft clearance combined with plastic compression could cause unforeseen issues.

Note: Oilite makes sintered and cast bushings - so it might be true that Oilite is advertised and what you get is 660 material bushings not the sintered bushing type that "absorbs" oil.

At this point probably my best bet is to get the shaft hard chromed - if someone will give me a name of a good shop in LA I will call them. First get new bushings, install and measure the resulting ID, then I will have a target for the final chromed shaft dia. 1 to 1.3 mil dia. clearance sounds about right to me.

What does all this sound like? Comments?

-Henry

Henry,
Google is your friend...Make some calls, and get a ballpark for the work you want to have done. Be prepared to describe application and ask for recommendations for hard chrome thickness. Your shaft may be ground undersize in the two bearing locations, built up with hard chrome to an oversized condition, and final ground to your specification. Grinding is a very precise process, so tight tolerances should be no problem. i.e. +/- .0002 - .0003 should be no issue for a competent grind shop.
Remember the economy is slow, so you have some buying power.
Hope this helps.

I googled and at least one looks like they might do a small job, I'll call down on Monday and also ask regarding what they recommend for the situation using 660 bronze or sintered - clearances/etc.
Thanks.

I'm sure many will disagree with this...

Head over to RMG in Sunnyvale and have them do the factory update. They have the factory tool to bore out the ears and you can go with the official Porsche update. Dan and I did mine and while the process was definitely sphincter clench inducing I have had zero problems. They have been at it for a long time and this is the fix they prefer.

My $0.02