linderpat

will do. I'll pull it all together this week, and get it out by the weekend.

Jerry Feather

Now I am thinking that what these cups/washers may need is some kind of metal washer inside them to bear on the seat adjustment screw in order to relieve the wear on the plastic in the cups. I wonder if I can find some very thin washers to fit inside of the cups to do that. I will look into that.

Jerry Feather

Then another thought is why not simply make these out of aluminum bar stock rather than plastic?

The steps for doing them in plastic will be as follows:
1. Set up the band saw and cut the left over plastic from Spare Tire Covers into strips wide enough the make the spacers.
2. ABS glue two strips face to face with ABS glue and clamp them to set.
3. Stack the glued strips in the mill vise and drill the center holes in them spaced accordingly.
4. Cut the individual strips in between the holes, then perhaps dock the corners of each resulting square.
5. Make a mandrel out of round bar stock and bore and tap it to the size of the center hole bolt.
6. Stack several small blanks onto the mandrel bolt and bolt it to the mandrel in the lathe.
7. Turn the blanks to round, then remove from the mandrel.
8. Counter bore each blank to the diameter and depth of the cup. (I haven't figured out yet how best to hold each spacer blank to do this.)

The steps to do these in aluminum are as follows:
1. Chuck the bar stock (probably 3/4 inch round bar) in the lathe and face off the exposed end of it.
2. Counterbore the bar with a quarter inch bit to about 3 or 4 inches deep.
3. Counterbore to the finish diameter of the center hole to the same depth.
4. Counterbore the end of the shaft to the depth and diameter of the cup.
5. Set the lathe and cut the end of the bar off to the correct depth of the spacer.
6. Repeat for each spacer until reaching the depth of the original counterbore, then rechuck the bar in the lathe and start at step 2 again.
(Note: there will be a slight deburr of edges after each cut.)

linderpat

broken washer in the mail today to you jerry. o/d of screw is 13mm per my measurement.

Texas993

I'm a newbie in the 928 group, but certainly no stranger to Porsche. I'd appreciate having the opportunity to purchase some of these new washers if/when produced. My DS moves with every stop. 40k mile car too. Age, not use!

Many thanks

no.radar

I'm sure of one thing... those parts are made of the same kind of turns-to-dust plastic the Germans used on everything back then. On my '80 928, I barely touched the grille-bar supports not long ago, and they literally turned to gravel between my fingers.

Oh well, I guess eventually, age gets the best of every thing, and every body.

Jerry Feather

Interesting. Those items are another project in my radar. Recently I had my 82 hauled home on a roll back when the battery ran down from a failed alternator and when we rolled it onto my parking pad behind another one of my cars it got away from us on a slight downgrade and bumped the other car. Later I found three pieces of the grill bar supports on the concrete under the front of the 82. I have some thoughts about how they too might be redesigned to eliminate the need to replace them after each such event.

Jerry Feather

As usual with some things 928 I remain pretty well confused about just what this item for the seats is and what it is actually doing. Too much of the information posted in this thread is not very helpful and is actually pretty misleading, so far. The item(s) in question has been referred to herein as a "race," a "cup," a "spacer" and as a "washer." The most common reference used by Ed is "washer." Stan explains that with the items missing the seat will move fore and aft by itself in normal driving.

From the pictures Ed has posted I can't see how this plastic washer is doing anything other than limiting the travel of the seat fore and aft on the adjustment screw as it gets to either end of its travel. I can't see how the absence of these washers/spacers allows the seat to move for and aft on the adjustment screw in any way. I still have no idea why these items would be referred to as a "cup." Maybe when I receive the pieces Ed has mailed to me I'll have a better idea about some of this.

No one has responded about my suggestion to make them out of aluminum bar stock.

Zirconocene

I'm not totally clear whether or not these things would fit my '90 but if they do, count me in for the aluminum versions. I love the idea of these fixes that should outlast me, and any foreseeable future owner.

Cheers

linderpat

Just as a reference, none of my seats experienced this movement at the end of their travel. I'm not sure what these parts did either, other than act as limiters of some sort. Jerry, hopefully you'll have them in hand today.

Jerry Feather

Thanks, Ed. I'm counting on them being in today's mail also.

Stan, Where are you. I still need your explanation about how the absence of these "rings" will allow the seat to move fore and aft a bit in normal use.

Jerry Feather

Ed, how did you take the measurement of the outside diameter of the screw thread on the seat adjustment screw shaft? Ruler, tape measure? caliper, or maybe even a micrometer. I need one pretty exact, since 13 mm is about 13 thousandths bigger than a half inch, and a half inch hole is easy for me to create whereas 13mm is more difficult.

linderpat

I used a caliper, then laid it against a steel ruler. If it is that close, it is probably 1/2 inch, BUT - the Germans used metric. I'd say 13 mm is it. When you get the washer you can measure from that - it is in 2 peices.

Jerry Feather

Thanks Ed. I received the pieces of the black ring, but it is in 6 pieces and too difficult to try to put together to measure. I can measure the width of it, the depth of it and the nature and extent of the bevel in the inside diameter that I didn't know it had. The most interesting thing about the pieces is that they are not plastic but rather some kind of hard rubber compound. I can invade it with my thumb nail. What that seems to be telling me is that what these things are is some kind of bumper and maybe with some spacer purpose also involved.

I could make some of these out of plastic, as I previously thought, or even aluminum, but I don't think that will accomplish their intended purpose very well. I actually have a stick of round bar material that is kind of hard rubber like, but I don't know what it is, why I have it, when I bought or where I got it, but it is too large around at 1 1/2 inches diameter. I'm gong to look into finding the same material somewhere at 1 inch or better, 7/8 inch, diameter and maybe make some of these with that. That is if it will machine ok. If I am able they wont be gratis as they would have been out of my scrap ABS plastic.

By the way, for anyone following Stan's suggestion about these pieces being missing and the seat moving back and forth, I'm pretty sure that that movement is caused by something completely separate from these bumper rings being missing.

linderpat

That’s too bad they further broke. They are very brittle for sure. When I mailed them, it was in two pieces. Anyway, I agree, their absence does not affect seat movement. All of these were disintegrated on both of my seats and I never had a seat movement problem.