G50 fork shaft upgrade test results

[hcoles]

Hello G50 Owners,

About 4-5 years and 25k miles ago I did a top end rebuild and complete clutch replace and fork shaft upgrade. Of course the needle bearings were toast.
I purchased a kit containing upgraded bushings and shaft. The kit type was the one where drilling out the transmission ears was not needed. I have the engine out now so I decided to take a look at the bronze bushings and shaft to see how they are living.

Here is what I found. I would like any comments on what to do from here, e.g.:
1-just buy another kit and put it in
2-lubrication options
3-purchase another type of kit
4-ask for a free or reduced cost replacement

It looks like the shaft does not have a very hard surface.
The bushing picture is a bit messed up because I ran a ball hone through it to clean out the gunk. Still you can see the marks and pitting. The play is considerable on the "loaded" side. The other bushing was in pretty good shape. This bushing runs in a dirty environment and the combination of clutch dust (there is very little clutch wear and dust in the bell housing) and lube it put in made a black rather hard coating on the bushing and shaft. Reuse or rotate and reuse, I don't think is an option - too much play now on one side and debris will get in immediately.

[Nine9six]

May I make a suggestion...
1. Clean hone the bushings so they are both the same size.
2. Have the bearing portions of the shaft ground maybe .003 - .005" undersized.
3. Have the same area hard face chromed to an oversized condition and then ground to a proper clearance fit for the newly sized bushings.
I guarantee you wont see that kind shaft wear again

P.S. How many miles/years, since did you do the bushing/shaft upgrade job?

[hcoles]

Yes, I like any suggestions... put about 25k miles over 5 years or so on the "upgrade"

The problem I have with your suggestion:

1- is there a place I can send the parts in and get this done? I don't have access to the machine shop I had at my old job. Seems like the key thing is to get the shaft turned down and chromed up to the target final original size - where can I get this done? Then get new bushings.. maybe ask to buy just the bushings. The shaft needs to be the original final size to fit in the trans. ears. Your suggestion sounds good, anyone else out there think this is a more durable solution?

Comment -why do I pay for an upgrade and don't get good engineering? or at least I'm not feeling like I got good engineering...

[hcoles]

been reading online re. hard chrome plating - sounding pretty good to me.
Got to be better than what looks like mild steel that I have.
I'm looking for a place within driving distance from here - ~ San Jose CA.
I have no idea of cost for a one time small job. I'm willing to give it a shot.
Maybe I'll find a Porsche friendly type of place :-)

[Lukesportsman]

I'd personally try to find a great non-P friendly shop and save the P tax. Check with a Harley Davidson shop since they are always chroming and machining parts. H-D is less expensive than Porsche in respect to upcharges. Then again in CA, your in VW/sand car country...they are quite used to transaxle issues.

[john walker's workshop]

looks like it was running dry. optimoly long lasting grease is good to use. i would just start again with new stuff, and grease it good.

[hcoles]

that's probably what I'll end up doing, I'm sure I greased it initially, might have used Redline wheel bearing grease, can't remember. I'll see if I have any optimoly or order from PP when ordering the other stuff e.g. TO bearing, which also has noticable play but not rough.... yet.

The concern is that the grease attracts the debris... but not sure it can be avoided. I might look for bushing material that doesn't require grease, but then I'm into an engineering project that could result in a better or worse result and at the same time used up time and $$.

[Nine9six]

Originally Posted by hcoles

been reading online re. hard chrome plating - sounding pretty good to me.
Got to be better than what looks like mild steel that I have.
I'm looking for a place within driving distance from here - ~ San Jose CA.
I have no idea of cost for a one time small job. I'm willing to give it a shot.
Maybe I'll find a Porsche friendly type of place :-)

Any small grinding shop can do the entire job for you, once you give them the final bore sizes of the bushings.
A local grind shop ususlly works directly with a local hard chrome shop. If not, any engine maching shop or small job shop can do the job.
This is a grind, plate, grind process. The shaft is ground sligntly (.003 - .005") undersize. The chrome is applied to an oversize condition, and the grinder applies a nice ground finish final size to a predetermined clearance to fit through the bushings.
Doesn't get much simpler.

No disrespect, but dish the HD shop suggestion. You want HARD chrome, not cosmetic chrome. There is a difference.

P.S. Even hard anodizing would be much better than bare mild steel. Not sure about the thicknesses that can be applied with hard anodizing.

Processing houses (anodizing or hard chrome) in your area should be able to give you all the details.
Again, this process will outlast 5 NEW reinstalls. 5 yrs and 25K is in my opinion, not much bang for your bux and time. Do this correctly one last time (probably for less $ than a new kit) and that should be the end of your worries.
Google is not only local to San Jose, but can be your freind in loacting a local shop(s) for all your needs.

Cheers!

[hcoles]

a bit of an update - I called the place I bought it from and they mention that not advised to use lubricant. I may or may not have done that, I don't remember. They are going to look at the photos and advise. I mentioned the hard chrome process/etc.

[Nine9six]

Originally Posted by hcoles

a bit of an update - I called the place I bought it from and they mention that not advised to use lubricant. I may or may not have done that, I don't remember. They are going to look at the photos and advise. I mentioned the hard chrome process/etc.

If you do decide to do the grind, plate, grind fix; only the bushing jorunal areas need to be hard chromed, not the entire shaft.
Best of luck to you...
PK

[hcoles]

good tip, thanks may save some $$ on hard chrome process if I do that.
I'll post resolution

[Quicksilver]

Originally Posted by hcoles

that's probably what I'll end up doing, I'm sure I greased it initially, might have used Redline wheel bearing grease, can't remember.
. . .

Wheel bearing grease definitely won't live in a application like this.
Optimoly is a pain to find. The one easy-to-find alternative is Bosch distributor grease. You can get it at many VW shops and it will stay in place at temperature.

[hcoles]

Update and Comments:

- went to a place that does hard chrome - ~ $175 to get the shaft done - so I decided to wait for kit supplier to look at a "new" kit coming in to see if materials are different or any additional info. is coming out. The owner of the hard chrome placed mentioned that a self lubricating type of bushing materials could be considered - e.g. one of the plastic types - some good up to 200F or more

-we have a big difference of opinion - supplier says don't use any lube, some here say use lube - I think some bronze bushing materials against steel can be or are considered self lubricating. I don' t know which combinations or types of bronze bushing materials are the self lubricating type. I forgot what the original instructions say, I can't imagine I would have put lube if it said not to, not sure it was mentioned in the instructions - 4+ years ago. I might still have the package.

- the most likely out come is that I'll get a new kit and install it and see what lubrication instructions are put forth by the kit supplier.

- I'm looking at iglidur Z bushing material

- what is the usual force that the clutch slave cylinder would put out? Is the clutch slave and master diameter the same, I can measure the lever ratios and try to estimate the force on the bushings.

If this situation breaks the ears off my transmission, I'll be just about the most unhappy P car owner around for awhile.

[KTL]

Clutch master is a 19mm. I don't know what the slave diameter is. Should be easy to measure since you've got the trans out and the slave disconnected.......

There are bronze bushings that are self-lubed. They're often called oil impregnated. You can also get bushings that are Teflon lined like Ina's Permaglide

Schaeffler Technologies (INA)  | Products  | Permaglide®

Or GGU's bushings

http://www.ggbearings.com/pdf/literature/productrange/PR_US.pdf

One of the members here on Pelican, cgarr, uses bushings like these in his rocker arm rebuilding process. Seems like a similar application here- rather heavy load and small amount of rotation. However the clutch situation is not bathed in oil like a rocker arm. Still, a lined/self-lubed bushing is better than no lube at all......

[hcoles]

Kevin,
thanks, helpful info.
I remember reading re. cgarr rocker bushings.

The slave is still hooked to the hose right now, but I should take it apart and see what shape it is in.

I guess another appraoch is to get the clutch foot pedal ratio.... I'll have to go look I guess.
Right now making a wild guess at 500 pounds force per bushing at the shaft.
Now that I've said that 1000 pounds pulling on the throwout bearing seems a bit much, so my estimate is probably high. I'll bet it is more like 200-400 pounds to get the clutch diaphram to move. That being said there is a probably a clamping force listed somewhere.

The bushing people will want to know the bushing load, is why I'm asking.
I'm also figuring 200F or 150F to 200F max. in there, some air is moving around so there might be some cooling, don't know.

[hcoles]

for possible future reference, here is an approximate drawing of the upgrade kit bushing.

[tctnd]

Look at the bushings under a magnifying glass. If they are oilite they will look porous (it's made by sintering tiny bronze spheres together). Grease will ruin oilite by clogging it. Lubed with heavy oil it should last a long time. If they are solid bronze grease is appropriate but they really should have provision for regular lubrication or they won't last. And finally, if grit gets into either, it will imbed in the softer bronze and wear away at the shaft. Particles from your hone will mix with gunk in the oilite (if that's what you have) and create a sort of grinding compound.
regards,
Phil

[hcoles]

Phil,

Thanks, it is likely I have the worst case of all you mention.

The bronze looks very much like the 660 I used on my rockers, but I haven't put under a glass and my eyes aren't getting any better... I have the question into the "supplier" to tell me what they are made out of.

If the "new" setup is just straight bronze then it sounds like that isn't a very good design - doesn't lube itself and shouldn't run without lube. If adding lube causes debris to build and then wear the shaft and bushing then I'm sort of screwed.

The hope is that the "new" replacement is Oilite type bronze, I can put a drop or two of oil on them and go with it. Check'em in 4 years.

Stay tuned.

[jimbauman]

Maybe the old setup that lasted almost 15 years isn't so bad!

JB

[hcoles]

well yeah, the original not so great Porsche design, that only lasted 15+ years, doesn't seem so bad now.

I got a small magnifying glass and looked couldn't see anything like balls pressed together.