Swapping your king/link pins for heim joints

[petew]

Over the last 15 years or so I've been one of those idiots who stuck with King/Link pins for time trials where you need proper steering. Some time back I came across a setup that involves replacing your K/L pins with something better. Now sure, you could just rip out the K/L beam and put in a B/J unit. However, for those of us having/wanting to keep our stock beams, this a is a great way of getting adjustable camber at a bargain price. The guy who came up with this is a local VW racing veteran, Greg Mackie. He's used this on a road racing 58' beetle so he could add 4 deg of neg camber so as to use a steel spool in the back end of the car. He couldn't believe the difference it made to turn in and grip.

rosejoints1.jpg

rosejoints3.jpg

The setup uses two 18mm heim/rose joints (the same size as the stock king and link pins). This size is really totally over-engineered for most of. You could use quality motorsport/aerospace joints, but that's way above spec. Our local, road racing, 5litre, V8 supercars use a 5/8" heim for similar purposes. A rear engined beetle will never get close to hurting an 18mm joint in regular use.

The only thing that needs to be fabricated is an upright pin that will go into the stock kingpin spindle. You can have a pin turned up on a lathe as above, or even use high tensile threaded bar/cap screw and fasteners with spacers. Greg suggested there are a number of ways of doing this. In fact, you might choose to use this setup to lower the car as in the pic below.

rosejoints4.jpg

There will be some people who want to suggest the heim joints are not designed to be mounted thus in sheer. Strictly speaking, that's correct. However, because we're using such large diameter joints, it's more than safe enough. I've been consulting with an engineering signatory in NSW, Australia. Modification laws here are some of the toughest in the world, yet my engineer is more than happy with the setup.

Here's the joints I'll be using. Scroll down to page 6.

https://tech.thk.com/en/products/pdf/en_a23_006.pdf#5

Their static load rating is 29.4 tons. Ie. well over spec for what we're doing.

The other good news is that dust covers and seals are now commercially available for most heim joints. Even still, at AU$50 a joint, I could replace them yearly and think nothing of it. The whole conversion is literally bolt in and requires no machining of existing steering/suspension parts.

[ChadH]

This is really interesting - and so simple, I'm surprised no-one has done it before. The possibility of adjustable spindle/ride height is intriguing too. I'd be interested in any future reports back on long term durability. Even though my current build is McPherson, I have LP '64 that I may drag out of the weeds some day.

[Ol'fogasaurus]

"... There will be some people who want to suggest the heim joints are not designed to be mounted thus in sheer. Strictly speaking, that's correct. However, because we're using such large diameter joints, it's more than safe enough. I've been consulting with an engineering signatory in NSW, Australia. Modification laws here are some of the toughest in the world, yet my engineer is more than happy with the setup.'"

I suspect you are talking about me . If your engineer is good for it then I guess it should be OK but I would still be leery about it myself.

What I am talking about mostly is the threads (looking like they are) in the trailing arms as I remember; there is usually a fairly short shank on heim-joints. I am concerned about the threads as well being concerned about the balls working in the non-linear direction causing the small amount of meat and yes, there is an arc on the inside adding a bit of meat to hold the balls in place. When I was introduced to them I was told that the basic design was never intended to work this way; it was to be more or less linier. We used them in a triangular/pyramidal shape to gain strength via working opposed to each other.

It kind of reminds me of elongating the slots in BJs for longer suspension travel which don't usually have a long life.

I do like basic the idea though.

Lee

Tried to clarify my thoughts. Lee

[petew]

Actually the threads don't hold the heim joints in. The joints are bolted in. A nut holds them into the arm. The clamps just help a little.

BTW, I totally understand what you're saying "the basic design was never made to work this way". I too looked at it and wondered. There is no doubt a better way to do it where the joints only work in a linear manner. That's BJ arms though. I was thinking through whether custom arms with Heim joints screwing in the ends would be preferable, but really they're just a different version of the same 'load in sheer' issue.

I guess what we're really talking about is a band-aid solution here. But then almost everything we do to make VW suspension better is just that anyway.

[Ol'fogasaurus]

Actually the threads don't hold the heim joints in. The joints are bolted in. A nut holds them into the arm. The clamps just help a little.

Are you saying that the threads are internal and a bolt clamps them to the arm; if so I read the picture incorrectly. I thought that the polish on the shank of the bolt didn't allow the threads to show and I apologize. There are quite a few styles or Heim-joints that are both internally threaded and externally threaded.

I am still concerned about the balls and the body of the heim-joint though.

Update: I'm still thinking about this:

1) Is the shank of the heim-joint going through the trailing arm with the bolt clamping it to the arm or

2) does the shank sit on one side of the arm with the bolt going through the arm itself therefore it clamps the heim-joint to the arm?

#1 might be OK but #2, the threads might be still in shear depending on the bolt being fully threaded or on the length of the shank.

Remember, torqueing the bolt causes the bolt to stretch some as it's threads move up the threads in the heim-joint and both the threads in the heim-joint and the bolt are being pulled in the opposite directions maybe stretching the heim-joint some. Over-thinking maybe but it needs to be considered.

[petew]

The threads are external.

As regards the ball and body, as long as the joints operate within appropriate angles they should be fine.

[Ol'fogasaurus]

You mean that on hard landing when you hit the stops shouldn't affect the spherical rod ends? For everyday riding I suspect you are right, the same with replacing them due to wear on a regular basis, I am sure that will be necessary too.

Anyway, my thoughts were meant to stimulate thoughts on the potential positives and negatives with the use of heim-joints/spherical rod ends. It was probably 40 +/- years ago that I had to sit in and listen on the design and uses for the heim-joints.

https://www.bing.com/images/search?q=sp ... &FORM=IGRE

[ChadH]

Do Heim-joint manufacturers offer specs on maximum lateral load (side load in the joint?) Just curious how these would compare with, say, the force required to press a regular ball-joint into a ball joint control arm - for comparison.

[Ol'fogasaurus]

As I said, it has been a long time since I worked with this kind of stuff but if I remember correctly: if it is intended to meet a fed standard (NAS, AN, MIL, etc.) then yes, there would/should be a standard for this and each lot would have tests and other requirements attached to each lot. I seem to remember that even then we called in the Mfg. to get their opinion at times if our material engineering group and stress didn't have all the answers. Not sure about CAD now day with the Boolean logic added to the C++ dataset.

If it is a manufacturing company's standard only then the company would have their own proprietary standards with a set of standard tests and "go/no go" jigs for checking. Since they would be proprietary I am not sure if they would give them out unless there might be a large sale involved. They also might work with you w/o giving away their standards but you might have to supply a lot of information as they might have some liability. We've had manufactures come in and after some dialogue and figures say "NO".

I remember when Nyloc nuts first came in; we could use them if they met our company standards until they became a (new?) fed standard and met those standards. Similar to the old style of wire latch quarter turn fasteners and nylon wire ties, we could until they would not meet Fed standards (The quarter turns meet EAA the last time I looked but not FAA. They would also not last under 12 G loading. The cut end of the nylon wire was wearing against other wires so they went back to lacing. Not sure what is going on with this now days) for several different reasons.

Things are not always as simple as they seem to be. (Oh, yeah!)

[raul arrese]

How much travel are you getting before the rod ends bind ?? I like the idea and wondering if the travel will be enough for air ride cars..

[Ol'fogasaurus]

Do Heim-joint manufacturers offer specs on maximum lateral load (side load in the joint?) Just curious how these would compare with, say, the force required to press a regular ball-joint into a ball joint control arm - for comparison.

Chad, your "pressing-in" question is part of my concern on the use of the rod-ends in this way. I wonder if the pressing in is directional; e.g., one side only is for the pressing-in. Its been a very, very long time since I was given direct detailed info on them.

If you looked in some detail in the URL I posted it showed a lot of them. Some of them have bushing so the bushing are probably pressed onto the "ball" then that assy is pressed into the joint. Some had no bushings and there were some that had "oil caps" that allowed oiling by hand which is interesting to their use.

Usually pressing BJs in isn't that tough, it is the aligning them for pressing that is the hard part . I have a 20-ton press and it hardly uses much pressure to press them in. They even have hand tools kits to do it.

It is the pressing the old ones out that can be scary. I've had the press literally jump off the floor when the BJ broke loose. Nasty things!

[4agedub]

I've been down this road and actually converted back to link pin. The 2nd pic you posted was in fact from my old car.

The issues I found in circuit racing;

The outer arms are way too soft for circuit racing and flex. So 3.5' static camber goes to 0' whilst cornering. We tried supporting the arms, shock towers and h-beam which did not improve the problem much. We had one failure of the bottom spacer. But that could have been due to using the wrong material. Not once did we have any issues with the heam joints or through bolt.

From 3.5' camber to this...


The solution was to convert back to link pin and bend the outer arms blacksmith style to get the correct amount of camber. The link pins give extra support to the arms and actually bind up when the arms start to bend. I know it's crude, but it works.

[petew]

Thanks for your comments. I really admire your work. I might have a go anyway. If I do, I'll had a support bar for the lower arm. As you say, that's where the problem is.

[4agedub]

I've tried this as well, the angle is crucial otherwise it will bind.... then gave up on the idea and built a 1303.

[petew]

Greg did the same thing and swore by it. He said the support bar was the best improvement. I wonder whether offroad gussetted trailing arms would help too.