Stiff king pin rotation

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Morris
Posts: 109
Joined: Wed Aug 08, 2018 12:05 pm

Stiff king pin rotation

Post by Morris »

I am wondering if anyone else has had this problem with the lower suspension wishbone, and if so what the solution is…

Looking at the photo below you will see that once assembled, my off side top king pin trunnion doesn't line up with the chassis mount! I've slackened off all the nuts including the wishbone camber nut (they of course were not tight anyway), but there is still a 10 mm or so misalignment. If I first fit the 1/2" bolt through the top trunnion, then the 7/16" bolt will part fit through the lower chassis mount and the phosphor bronze bush but of course not through the other side of the chassis mount due to the misalignment.

[attachment=1]IMG_20190305_231619 (2).jpg[/attachment]

The near side king pin fitted ok although the lower 7/16" bolt did need winding though the mount. The king pin swivels with very little resistance so the near side is ok.
I tried swapping around the top wishbones but I had the same issues (and laying one over the other showed them to be identical). I did manage to eventually get all the bolts in, with the final bolt being that of the top wishbone front bolt (that also takes the anti-roll bar bracket) although it did need 'screwing' in and forceful alignment in order to align the chassis bracket with the mounting hole of the wishbone. This though results in very high resistance in rotating the king pin.

I noticed during my own little investigation that both suspension assembly sides went together very nicely if I swapped over the lower wishbones to their opposite sides and so mounted them upside down (i.e. damper bracket protruding from the top of the wishbone – a novel solution but quite incorrect! More interestingly I saw that the metallastic bush eyes were welded differently on each wishbone, one was axial to the tube and the other was clearly not!

[attachment=1]IMG_20190305_231619 (2).jpg[/attachment]

I returned the wishbones to the factory who said that although they fitted their jigs ok and to an XI chassis, they would send me replacements which they did. Upon receipt I did notice that what I returned and what I received back were not identical...

I’ve now fitted the replacement lower wishbones. The near side one went onto the chassis ok once I’d filed a small amount off the chassis pickup point a little, and the king pin rotates very easily.

The side I had the trouble with went together easier, although there is still significant rotational stiffness in the king pin (the top king pin nut is slackened off).

My question (bearing in mind that the car is going to be very low annual mileage) therefore is: how do I gauge the point at which the kingpin rotation is too stiff and will result in abnormal wear or even failure?

Many thanks for all comments.

Morris.
jonclancy
Posts: 942
Joined: Tue Nov 01, 2011 9:30 pm

Re: Stiff king pin rotation

Post by jonclancy »

Hi Morris,

I’m no expert here, but maybe it’s worth checking the chassis mountings against another car? A tight kingpin could well wear and might affect steering self-centering. I could measure mine Sunday afternoon for you, unless someone else can beat me to it...

Not much help, I know, but that’s the best I’ve got! :D

PS Can you re attach your image, please? Can’t see it.
Morris
Posts: 109
Joined: Wed Aug 08, 2018 12:05 pm

Re: Stiff king pin rotation

Post by Morris »

Thank you Jon. It would be very useful to compare a dimension or two. I was looking for a datum on the chassis from which to measure, but maybe there is one that people already measure from? I would have thought that the suspension pickup points on the chassis are a critical part of the chassis welding jig, but unfortunately the factory have not come back to me for a while.

Oddly, some build diaries have alluded to this issue by stating the order in which to assemble the bolts to make the assembly go together smoothly:

xxx
There is an amount of caster on the front suspension and this is built in by the wishbone geometries. This relative difference between top and bottom mounting points (in the x-axis) prevents the hole in the lower trunion from sitting parallel to the holes in the wishbone mounting and so the bolt is hard to fit if the bottom is not fitted first. As the top trunion is 'rubber' mounted, the upper mounting bolt is easier to fit second.
xxx

There is no mention anywhere though of the kingpin being stiff to turn.


On another note, I've been having a bit of trouble with uploading photos with the website saying that:

'This page isn't working' www.westfield-eleven.org is currently unable to handle this request. HTTP ERROR 500'.

If this means anything to anyone I'd be grateful for any help in posting photos?

Many thanks.

Morris.
jonclancy
Posts: 942
Joined: Tue Nov 01, 2011 9:30 pm

Re: Stiff king pin rotation

Post by jonclancy »

If you choose the datum, I’ll get the tape out.

Cheers

Jon
Last edited by jonclancy on Sun Apr 07, 2019 9:29 am, edited 1 time in total.
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Stiff king pin rotation

Post by Westfield 129 »

Is the king pin properly fitted to the upright? I have received spindle/kingpin sets that were not properly reamed. I had to return them for proper fitting of new kingpins.

The other situation would be that the caps/upper mounting for the top of the king pin is not properly shimmed, and too tight. This will really tighten up the king pin and result in a lot of friction.

The mounting of the king pin/spindle assembly should move freely, and the angle of installation is of no consequence when the upper and lower arms are assembled as the king pin doesn't rotate, the spindle does. The main part that can bind the spindle is the top nut and the shims under it. If the nut is too tight, everything will bind up.
Sometimes, the shims are missing. In any case loosen the nut and the spindle should move freely on the king pin.
Morris
Posts: 109
Joined: Wed Aug 08, 2018 12:05 pm

Re: Stiff king pin rotation

Post by Morris »

Yes, I've slackened off the top nut and removed the bolt making the connection to the upper wishbone mount. The stub axle then rotates with no resistance against the trunnion, which is what I expect. The stiffness occurs only after assembling it to the wishbones which leads to it being a misalignment issue.

I can't see any misalignment though. The anti-roll bar lies parallel to the front chassis cross rail implying that the top wishbone chassis mounts are correct, and comparative measurements of the lower chassis mounting points doesn't show a difference between the two sides.

That leaves the lower wishbone itself, for which I have noticed a difference in part to part quality (between what I sent back and what I received back).

Have to say I'm a bit isolated by this now as proactive support from the factory has not been all that forthcoming...

Morris.
Splat
Posts: 461
Joined: Thu Jun 02, 2011 5:12 am

Re: Stiff king pin rotation

Post by Splat »

I apologise in advance; this post won’t be helpful to you! It’s just an observation.

Some five or so years ago, i rebushed my suspicion. (I looked into poly-bushes at the time, but they weren’t available off the shelf so I used the original Metalastic ones. They seem to be holding up well, but I’ve a set of poly-bushes for possible future use....... anyway). Unfortunately, one of the front lower wishbones got butchered and I had to buy a replacement from Westfield. Surprisingly, they had them on the shelf. Although it fitted, the quality of the fabrication was simply dreadful. The welding splatter looked more like a nasty disease. I expressed my concern on here at the time.

Didn’t learn my lesson though! Not long after, I bought a new exhaust manifold from them. It was quite possibly the most shoddy thing that I’ve bought EVER! I returned it and they were VERY reluctant to refund me. “Special order” and all that.

Spend a minute or two reading the first two posts on this thread viewtopic.php?f=4&t=568&p=4929&hilit=Exhaust#p4929
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Stiff king pin rotation

Post by Westfield 129 »

I don't understand the misalignment. The spindle rotates around the kingpin, and the king pin has no flex and is not attached to the spindle. There is no way that it can be misaligned. It's all straight up and down.

Loosen the spindle top nut and see if you can get the spindle to rotate about the king pin. That is the only thing that can bind the spindle.

I would love to see a picture.
Morris
Posts: 109
Joined: Wed Aug 08, 2018 12:05 pm

Re: Stiff king pin rotation

Post by Morris »

The scale is a bit off in my diagram but hopefully this will clarify issue I am having.

The diagram shows the kingpin assembly (in blue). The black parallel bars represent the upper and lower wishbone attachment points for the kingpin assembly with the horizontal red lines being the bolts.

[attachment=1]Kingpin diagram.jpg[/attachment]


The left hand diagram shows the kingpin assembly attached to the lower wishbone with the bolt, with the upper mount not yet being attached, but you can see the apparent caster built into the wishbone geometry.

The right hand diagram shows the kingpin assembly located into both the lower and upper wishbone mounts and the exaggerated caster angle of the kingpin assembly (in reality the misalignment is now between 5 and 7 mm following replacement of the lower wishbone by the factory).

[attachment=1]Kingpin diagram.jpg[/attachment]

It is therefore a real struggle to get the upper bolt through the other side of the upper wishbone mount as the metalastic bush in the trunnion does not allow enough ‘rocking movement’ of the bolt to allow for the 'caster' misalignment.

Once the bolt is finally in, you can imagine from the diagram that a bending moment is applied to the kingpin assembly which is the cause of the stiffness. (I’ve slackened off the nut up the top of the kingpin assembly so that I know it rotates freely prior to assembly onto the wishbones.)

I hope this clarifies my problem?

Many thanks.
Attachments
Kingpin photo
Kingpin photo
Kingpin diagram
Kingpin diagram
Kingpin diagram.jpg (9.77 KiB) Viewed 6537 times
Westfield 129
Posts: 867
Joined: Sat Jun 04, 2011 4:20 am

Re: Stiff king pin rotation

Post by Westfield 129 »

I need to see your actual front suspension installation to include both upper and lower arms. More pictures...
The anti sway bar is not a factor here, so remove it prior to the pictures. I need to see the upper arm installation, lower arm installation, and the whole thing, front/back top, and from the spindle king pin mounting to the chassis.

This looks like an installation error. Check left/right upper arm, lower arm orientation. It is so far off that there is something obviously wrong.
NOTE: Lower trunion mount goes INBOARD of the king pin. This may be opposite of the original Spridget mounting. Check carefully the orientation of the king pin upper and lower mounts.
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