Kingpin modification.

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KNO3
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Kingpin modification.

Post by KNO3 » Wed Mar 13, 2019 8:06 pm

I have been wrestling with the issue of leaking drop axles. I thought I had done everything that I could to get my Mule to stop leaving puddles from the kingpins. In the course of installing new axle boots I used spray gasket on the shims during reassembly in order to seal them up. Alas my efforts were futile. Still leaking.
I came up with another plan and thought I would share it here. I just did this modification today so I have not had time to evaluate the results. Time will tell if it is a successful endeavor. I made a groove in the kingpin and installed an o-ring in the hope that it will stop the leak.
Here is a pic of the finished cut. I made the cut to a depth and width that will accommodate the size of o-ring I chose.
Image
Here is the Kingpin with the o-ring installed. A. little trial and error led me to this result. The kingpin is a tight fit by itself so the o-ring could not stick out too far or it would get cut on installation.
Image
I hope that this prevents any future leaks. I'll post back in a week or so to report if the leaks have quit.
Regards, Frank

hummermark
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Re: Kingpin modification.

Post by hummermark » Thu Mar 14, 2019 3:45 am

I did this modification years ago on my mule and not had a weep since , well worth doing.
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Re: Kingpin modification.

Post by Auto Shop teacher » Thu Mar 14, 2019 5:41 am

Interesting, was there a problem with the king pin cap not being flat, or the steering knuckle housing having a high point? I spray gasket sealer on the shims and have had no problems with my stuff. I am glad you found a solution to a leakage problem.

muleman7
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Re: Kingpin modification.

Post by muleman7 » Thu Mar 14, 2019 11:00 am

I have not had this problem since using the following:

1-Most of the time the studs come out when unscrewing the nut. If not I remove the studs using a Snap On CG500 Stud Remover.
2-File the mating surface on the steering knuckle easy with no studs.
3-Replace the Studs using Loctite [Red]. I have 2 Snap On CG500 Stud Removers one with 5/16-18 the other 5/16-24. Stud is wire wheeled while held with the CG500 and the 5/16-24 threads chased with a die.
4-Wire wheel the pin and file the mating surface to eliminate any rough surface or high points.
5-Sand the shims to remove compound, rust and rough surface or high points. If shim is damaged or unable to sand smooth I replace.
6-With the shims dry I assemble and install the steering knuckle to check for preload with out the Boot or CV joint [3 pounds on a spring scale]. If preload is too tight then the pin may not compress the shims and could leak or damage the bearings/races.
7-Final instillation I used Never Seez Mariner's Choice but now use Permatex Aviation Form-A-Gasket Sealant. Copper Coat Spray is a great product but I find it takes longer to apply/double coat and is messy.
There are different sealants that could be used on the Pin and Shims that will work.
1-Loctite 518 red for all metals, Gap fill 0.010 unprimed 0.050 primed.
2-Copper Kote Spray or paste, fills minor surface irregularities.
3-Never Seez Mariner's Choice particle size 75 microns or 0.00295. Mariner's Choice offers unparalleled resistance to water washout and the best protection in continuous high moisture environments both above and below water lines. Applications that are exposed to harsh salt water and fresh water conditions.
Last edited by muleman7 on Thu Mar 21, 2019 2:05 pm, edited 2 times in total.
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Guam0311
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Re: Kingpin modification.

Post by Guam0311 » Thu Mar 14, 2019 11:54 pm

Seems like a great concept, putting an O-ring to it. Otherwise, it seems one has to have it absolutely clean and a flat surface to keep it from leaking?

What depth did you machine the groove to and what diameter is the groove? Do you have a part number for the O-ring?

Soon I will be assembling my two rear kingpins so this is very interesting.


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Re: Kingpin modification.

Post by Lance-W » Fri Mar 15, 2019 6:20 am

The absolute bible for O-Ring groove/gland design is the Parker O-Ring book. You can download it free. If it's not in this book you don't need to know it with respect to O-Rings.

http://www.parker.com/Literature/O-Ring ... 205700.pdf

Chuck W.
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Re: Kingpin modification.

Post by Chuck W. » Fri Mar 15, 2019 9:13 am

This is an interesting idea. I am concerned about the sharp corners in the bottom of the groove which could possibly lead to stress cracks and a broken king pin. Looks like you are using a parting tool to cut the groove. You might want to grind your tool so that it forms a radius in the bottom. Just my thought.

muleman7
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Re: Kingpin modification.

Post by muleman7 » Fri Mar 15, 2019 12:54 pm

The M274 Hubs had a 90 degree or sharp shoulder on the inside between the seal surface and hub. The hub would break at that point so with the A1, A2 and A5 a radius was designed and no more hub breakage.

I just finished working on an A5 and 3 of the hubs were the M274 style. I replaced the ones that were pitted and the seal leaked with the newer style hubs and new studs.

It was a 2WS and the rubber boots had MMA cast onto them and there was no groove for the safety wire they were replaced with the proper boot.

Image

M274 Hub with square shoulder use either the protruding OEM or flat faced seals.

Image

M274-A2 Hub with radiused shoulder only use the flat faced seal.

Image
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KNO3
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Re: Kingpin modification.

Post by KNO3 » Thu Mar 21, 2019 6:50 am

Current update:
All dry under the Mule! No drips since this was done.
Thanks for posting the O-ring guide. I compared my cuts to the chart and ended up quite close to those specs.
The cut depends on the o-ring that will be used.
I used a 1/2" ID, 5/8" OD, 1/16" Width o-ring. I wanted a thin o-ring to keep the cut minimized.
Originally I had one axle that did not leak out of the four so the shims and mating surfaces must have been all right with that one. I did the same to all of them during rebuild the others just did not cooperate.
I considered the possibility that this would weaken the pin. It is possible. The diameter at the cut is still much greater than the diameter at the bearing and there is enough length on the pin to keep good engagement with the steering knuckle. It is a gamble I am willing to make for dry axles.
Time will tell if it all works out. Right now I am satisfied with the results.

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