M35 dogbone bushing options

The other night, out in the middle of BFE, in my M35A3...

A farmer waved me down, leading to the discovery of a failed dogbone bushing. Thankfully this truck has a winch and it was the front bushing that'd failed. My buddy and I winched the axle back into line and crawled home. It happens.

Now that one has failed, I'm obviously going to be eyeing the rest for replacement as well. A few questions for folks who've done this before (@Jeepsinker):

What options are there out there? What service lifetime should I reasonably expect? What do people like/use the most?

Thanks,
SJ/JD

I have not replaced any of these yet but I believe the only 2 options are nos replacements and ball joint style upgrade. The nos parts are easy to find but I have not seen the ball joint style listed anywhere although I heard they can be costly.

I want to do a experiment where I remove all of the rubber from one that has failed and fill it with polyurethane. If you search you will find that there are many automotive diy enthusiasts doing this with car mounts and bushings. The reason I say I want to experiment is because I don’t know how well the adhesion and shear strength would be. If this is a viable option and the poly adheres to the steel and can carry the load without tearing you could save hundreds of dollars on this repair as the poly would cost less than what 2 nos bushings would.

The ball joint style are your best option. They're available from Big Mike's for about $100 each, but you can expect them to last longer than you have the truck. If you grease them regularly, I'd wager a guess at a 25- 30 year service life on a truck driven often. They should also reduce axle wrap and wheel hop under load and on sand. I won't even bother with stock type bushings anymore.

Rubber rots from age and environment. Ball joints don't.

V8srfun said:

I want to do a experiment where I remove all of the rubber from one that has failed and fill it with polyurethane.

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I'm afraid that PU bushings cannot be glued or "hot-vulcanized" and then have it stick to steel like rubber does. And that regular PU as used in suspension bushings is not resilient enough in this case, for the joint to be able to twist enough when the suspension is articulating up to its limits; that is 15+ deg out of horizontal position, each axle, either direction. Which means a 7.5deg twist for each of both end bushings on one dog bone.

Jeepsinker said:

The ball joint style are your best option. They're available from Big Mike's for about $100 each, but you can expect them to last longer than you have the truck. If you grease them regularly, I'd wager a guess at a 25- 30 year service life on a truck driven often. They should also reduce axle wrap and wheel hop under load and on sand. I won't even bother with stock type bushings anymore.

Rubber rots from age and environment. Ball joints don't.

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I have them and fully agree. They calmed the rear end way down, especially when empty.

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V8srfun said:

I want to do a experiment where I remove all of the rubber from one that has failed and fill it with polyurethane. If you search you will find that there are many automotive diy enthusiasts doing this with car mounts and bushings. The reason I say I want to experiment is because I don’t know how well the adhesion and shear strength would be. If this is a viable option and the poly adheres to the steel and can carry the load without tearing you could save hundreds of dollars on this repair as the poly would cost less than what 2 nos bushings would.

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I have a buddy who used to build rock crawlers (coincidentally was in the truck during the recent bushing failure). He mentioned urethane but ultimately suggested against them because they're so incredibly hard (as in tough).

I'd love to have a ball joint option, even if they cost more.

cattlerepairman said:

I have them and fully agree. They calmed the rear end way down, especially when empty.

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Awesome. That's exactly what I was hoping might happen. Guess I'll bite the bullet and place the order.

You won't be sorry. I have a video on removing them easily without any special tools on my channel if you need help.

Jeepsinker said:

You won't be sorry. I have a video on removing them easily without any special tools on my channel if you need help.

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I saw the video - it's quite good (hence the reason I tagged you at the start of this )

FWIW, I expected the worst when doing my torque rods and, as it turned out, Murphy was on vacation. I was a bit surprised by how "easily" they came out (yes, BFH, hitting on the right places (on the side, not the stud) and the wood block/wedge method and I was aching the next day) but other members described way worse. My little shop press (8t) and a socket of the right size pressed the ends right out and the new ball joints (Erik's) in.

It's the same amount of labour as replacing with OEM style rubber ones ( a bit like laying down really cheap carpet; takes the same work to install as something really nice!).

IMHO the ball joints ride way superior. I think it is because the rubber absorbs energy from the axle movement by becoming deformed and gives it right back to the axle by returning to its natural position. That causes bouncing of the axles.

The ball joints do not have a "preferred" position to be in, so they just absorb the movement, change angle and that's it. No feeding back of energy into the axle.

That is my explanation as a non-engineer.

Jeepsinker said:

They're available from Big Mike's

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You can also find them on Erik's Military and Surplus. Erik's also carry a heavy duty option, and if you buy a few of them send an e-mail and ask for a volume discount.

montaillou said:

You can also find them on Erik's Military and Surplus. Erik's also carry a heavy duty option, and if you buy a few of them send an e-mail and ask for a volume discount.

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I didn't know that. Big Mike's Motorpool and Rapcoparts.com are the official sponsors of my YouTube channel, and they're all I use. They take good care of me and my viewers, so they of course have my preference.
No intention of downing any other companies.

I have zero horses in this race. The only thing I can do is to share what I've found:

Erik has 3 options effectively: NOS, NOS+, and heavy-duty. The NOS+ is NOS plus a plate to prevent the bushing doing exactly what it did with me the other night: popping out. Nice. The heavy-duty option is the ball-joint version which I'm going to assume is what is on offer with Big Mike.

I don't know why folks would want the NOS+ option (other than maybe cost) because it's already not stock at that point, but... the option is there.

Thanks to all for the input on this - it's the main reason this is my favorite forum of all forums I visit.

I have thought about machining cups or races out of UHMW to fit either side of the ball, and capture somehow, sandwich plates outside the joint probably. Similar to a "Johnny Joint" (rebuildable).

Big Mike is very active online, very helpful, great guy. Go-to for most of the country. Erik is less active and less known, but my go-to for the west coast because he's closer for shipping. Good guy as well.

DavidWymore said:

I have thought about machining cups or races out of UHMW to fit either side of the ball, and capture somehow, sandwich plates outside the joint probably. Similar to a "Johnny Joint" (rebuildable).

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It should be doable and I think it's a good idea - to at least give it a try. But first you will have to machine what you call "ball" to actually become one; that is, having a perfectly spherical shape.

Johnny joints are meant to be mounted in double shear bracketry, so you'd also need to fabricate new mounting points.

Very large rebuildable joints like this are already available on the market.

Jeepsinker said:

Johnny joints are meant to be mounted in double shear bracketry, so you'd also need to fabricate new mounting points.

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Yes, and to avoid that we'd need a "Davy" joint...