Author Topic: Prinz kingpin replacement.  (Read 2632 times)


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Prinz kingpin replacement.
« on: June 25, 2011, 07:01:41 PM »
One of the kingpins on my Prinz is a little loose, so I guess that would need addressing soon.

However, since I have never really worked with kingpins before (on VWs they were only used on very early stuff), I am not exactly sure how they work. I know the rough principal, that a metal pin spins around in some bushes, but apart from that I am not really sure.

I see on the NSU parts website, they sell bushes and thrust washers, which I assume are the consumables on kingpin systems? They also sell bolts and things, but I guess those don't usually wear out, as the soft brass bushes wear out first.

So, is it just a case of taking the whole assembly apart, and bashing the old brass bushes out and pressing new ones in, or is it more complex then that? I know with VW kingpins you need to have an adjustable reamer and do some kind of reasonably complex ritual with manually reaming the bushes to tolerance and stuff, although my knowledge of that is a little hazy.

So, a few questions:

1) Are Prinz kingpins adjustable, or is it a case of once it's worn it's worn and needs replacement (like ball bearings)?

2) What parts typically need to be replaced when a kingpin wears out? Is it just two brass bushes per side, or the thrust washers too, or what?

3a)Is it just a simple disassemble/reassemble type job, so basically all the parts fit right out of the box?

3b)If the answer to the above question is no, then do they require manual finishing/reaming/grinding/machining/lapping etc? Or perhaps there are shims or something that need to be manually selected for best fit?

Please bear in mind that this is probably the first time I have ever had to deal with kingpins, so I really don't know almost anything about them. Any help appreciated.


Bob Purton

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Re: Prinz kingpin replacement.
« Reply #1 on: June 25, 2011, 09:01:54 PM »
You will be surprised adi, its often the pin its self that is worn more than the bushes. By strange coincidence kingpins and engine mounts are the only two jobs I have ever done on a Prinz. You need to replace the pins and the bushes, they are not brass, no automotive bush is made of brass but Phosphor bronze or in later vehicles aluminium bronze. Brass would wear out in a week! Its a long time ago now but I'm pretty sure I had to reamer the bushes once fitted, you see even if the bushes started out with a perfect size bore once pressed in, the bore closes up a little so a small amount of material has to be reamered out, I use adjustable/expanding reamers for this ., you can buy them is sets or just one thats adjustment range covers the bore that you want to cut. Its easier than it sounds. As I recall there will also be some spacer shims to take up any up and down movement. Fit the pins and bushes and then test by trying to move the wheel hub assembly up and down, if there is detectable movement shim it up. Please bear in mind I've worked on a lot of cars since then but thats how I remember the set up.  Hope this helps.  Bob

Big Al

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Re: Prinz kingpin replacement.
« Reply #2 on: June 26, 2011, 08:17:08 AM »
NSU tend to wear out the king pin. When I did it you could buy a kit that included the knuckle joint. Since that is, from memory, a blind fitting on one bush that will be harder to ream. An adjustable line reamer is easy to use but I find the issue is to keep it vertical to the bushing. This is best achieved with a good die handle so forget molegrips etc. If you have not done it before first try it on an old bush as there is a knack to it. If you go at it the reamer can skip and you get an uneven finish since the materiel you are cutting, while great for machining, is scuff resistant - that essentially is what a bush is doing. So the adjustment of the cutter needs to be in handy increments to lift of a layer of material cleanly. I am no machinist but someone would be able to put this into tech speak.

While you are under there with this lot off check the other old fav, the steering rack end bushing inside the each end of the rack. It is a plastic machined compound and due to the angle the drop arms attach to the hubs they get a hard life. If you can get the part they are not to bad a job with the front in bits already. With the suspension done these cars are pretty good on handling though they are still a bit swing axle with all the problems that that brings if you get excited. The 4 pot cars went to a trailing arm and full double joint which made things much more predictable on the limit. It is possible to uprate the front to disc brakes and find wider rims if you hunt around. With a few engine tweaks these cars will out perform most things in their class if you choose to go down that route.
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