pedal cluster roll pin, fixed or not? Options

[flesburg]

I know that the hole through the "pedal" end and the hole through the "shaft" can wollow (spelling?) out and become elongated, because I have seen it. On one pedal cluster I drilled them out so they were round.

Roll pins are sold in all kinds of sizes, both english and metric. I do not have a metric drill set, but do have english in fractions and the numbered set (because I needed some once for some taps). Good fastner companies carry a wide selection of roll pins, and even ace hardware in the KC area has a large selection. The most expensive ones are made with spring steel.

If the roll pin fits tight enough that you have to drive it in, I do not think they will fail, but if you can push it in with your finger, then it is going to rock and flex everytime you engage and disengage the clutch, and eventually develop stress cracks. A loose pin will not only further distort the hole, but it will fail. So will a loose key in a sloppy keyway, therefore the reason in industrial machinery, that keys are held tight in a keyway with a lock bolt.

Is it possible that those of you who are having failures need to ream out the holes and use a larger pin in order to keep the pin from stressing due to "rocking back and forth" and stressing?

I suspect that both Porsche and Weltmeister just used the cheapest roll pins they could get their hands on at the time.

[bondo]

looks like jkeyzer needs to do a side by side pic of a weltmeister pin and a "current porsche" pin. (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

[mightyohm]

QUOTE (bondo @ Aug 28 2005, 07:59 AM)

looks like jkeyzer needs to do a side by side pic of a weltmeister pin and a "current porsche" pin. (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

That's basically what we just did, Rich posted a pic of his pin, and if you look at it closely, the metal is thicker than the one I posted. I will get a Porsche pin and show you both pins in the same photo if that's what it will take...

[John]

The roll pin that I had fail (Weltmeister kit from approx. 15 years ago) was a roll pin. (A single thickness of spring steel shaped into a coil).

The roll pin was almost one complete circle, not several wraps as shown in the photos posted in this thread. I would tend to believe that the vintage of the kits with problems was probably way back when my kit was put together (15 years ago), and the problem pins have been addressed.

I have no pictures of my failed pin as it failed some 15 years ago. The pin broke in 2 spots (at the stress concentration on either side of the shaft). I suspect that the bolt I used began to fail due to a sizing issue because it was not an interference fit.

The coiled pins are what the correct part should look like (as shown in the pictures in this thread). These high strength spring steel components are designed to slightly compress when installed (which is why the ends are slightly tapered). This profides for a very tight fit in the hole through the shaft and the clutch arm.

The holes in the shaft and in the clutch arm should be exactly the same size for the coiled pin to perform as intended (not allow any movement between the shaft and the clutch arm).


As far as I know this issue was addressed long ago.

If not, the coiled pins are available at better hardware stores, McMaster Carr, Porsche, or any number of other places.

Luckily, when one works well, you need not worry about it for years.



just my $0.02

[motorphotog]

Here is the photo of the Weltmeister pin that failed on me.

It broke in 3 places, both ends and the center portion staying in the long rod

[ArtechnikA]

i think what we've established in this thread is:

• All pins used in this application will eventually fail.
  
• Ovalled holes in the pedal and/or shaft will make matters worse/
  
• There -was- a batch of bad pins in the distribution chain a while ago.
  
• The current kit pins are substantially identical and appear to be working in service.
  
• The dealer pin is still available from the dealers and is cheap.
  
• The ultimate solution (what Porsche eventually did) is a hydraulic clutch, which is not cheap.
  

[mightyohm]

The only thing we're missing is whether the Weltmeister pins consistently have a shorter lifespan than the Porsche pins, despite the switch to a spirol design. The Porsche part is visibly made from heavier gauge steel so it may be stronger.

[ArtechnikA]

i agree, but i donno how to test that, zackly.

to an extent, the pins supplied with the bronze bushings are a victim of their own success. with the factory plastic bushings, they'd wear out, and you'd replace them - using a new pin. when the master cylinder seal failed, it'd flood the pedal cluster with brake fluid, and the bushings would swell, and you'd replace them - using a new pin.

now, the bronze bushings last long enough that the pin, not the bushings, are the wear/failure item.

[ein 6er]

side by side

[cooltimes]

As cheap as these roll pins are at your local hardware store, just do an annual on the replacement. Takes only a couple of minutes if you catch it before it breaks, shears, whatnot and needs replacing

[mightyohm]

A couple minutes? It took me a couple hours just to get the cluster back in the car. And that took a lot of contortions to get the clutch clevis back on. It's not one of my favorite jobs, that's for sure.

[cooltimes]

Couple of minutes for replacing the pin itself is what I was saying but if it took you a couple of hours, that is cool. I work a little faster myself. I have done that job numerous times considering 31 914's I have owned and driven since the summer of 1970. Even helped a few buddies replace their's too. Paid less than a quarter for some of those pins. Guess the price now is adjusted for inflation like the gas thread. LOL

[mightyohm]

Ok, here they are, side by side.

Weltmeister pin on the left. Porsche on the right.

The Weltmeister is very obviously made from a lighter gauge steel, and is also a larger diameter, so it compresses more when installed.

Conclusions?

I for one am going to swap out for the "real deal" when I get a chance. There is a clear difference in strength between the two pins.