Those with A3 rims that don't leak... Clamp ring tightness

[HDN]

The one wheel I mounted on the truck has lost 8 psi over three weeks. Without having done a leak test, I suspect it's because I don't have the clamp ring on tight enough because the distance between the end of the clamp ring stud and the top of the lock nut is about 1-1/4". The other wheels I haven't touched yet have a distance of 1-3/8" there. Granted, those wheels all leak, but that might be because of the valve stem grommet (haven't confirmed that though).

If this is a problem, it's probably because I am being way too conservative with the gear train efficiency on the 1:64 torque multiplier I'm using (I'm assuming 15% losses). I'm going to experiment with my bigger torque wrenches tomorrow to see if I can figure out a more-accurate gear train efficiency value.

Anyway regarding clamp ring tightness and the amount of stud showing, any thoughts?

 

[simp5782]

I've put hundreds of wheels together using a 1/2" Dewalt impact and never had one leak from beadlock nut tightness. You may have an o ring pinched or warped more than likely

 

[Monkeyboyarmy]

How did the oring groove look? I've seen a bunch of those wheels rust at the oring area.

 

[HDN]

I've put hundreds of wheels together using a 1/2" Dewalt impact and never had one leak from beadlock nut tightness. You may have an o ring pinched or warped more than likely

I'm curious about what specific DeWalt impact you're using as well as the torque spec. I'm using a DeWalt 1/2" impact as well, but I'm trying not to go too crazy with it. I also learned recently that compared to at least the M939A1 super single rims, the M35A3 rims require nearly twice the torque per clamp ring nut.

How did the oring groove look? I've seen a bunch of those wheels rust at the oring area.

So far the sealing surfaces looked okay. I didn't observe major pitting, but I still cleaned them with a wire wheel, applied rust converter, and painted them. The o-rings I've removed so far were smushed into a triangular cross section, so I'm thinking they should seal pretty well even with some uneveness along the sealing surface. Provided I tighten them up enough!

 

[glcaines]

I haven't had any of my A3 tires leak air after removing and refitting. The secret is replacing the valve stem grommet and torqueing to 45- 60 Ft-Lb, using a socket that has been ground to a sharp edge to firmly grip the brass nut. I also replace all nuts with new. Then, cleaning and painting the O-ring groove sealing surface, using a new O-ring and making sure it remains properly in place during assembly and then torqueing the nuts to 425 - 475 Ft-Lb. This can only be done accurately via a torque wrench. If these nuts need to be re-torqued after assembly I would highly recommend deflating the tire prior to re-torqueing. I don't use any sealants, etc. during assembly of the valve stem grommet or the O-ring. The procedures can be found in TM 9-2320-386-24-1-1.

 

[HDN]

If these nuts need to be re-torqued after assembly I would highly recommend deflating the tire prior to re-torqueing. I don't use any sealants, etc. during assembly of the valve stem grommet or the O-ring. The procedures can be found in TM 9-2320-386-24-1-1.

After reading about the kid who got a clamp ring embedded in him after trying to service a FMTV rim at 50 psi or so, I'm definitely deflating the tire to zero before trying that (spoiler alert - he was killed pretty much instantly ).

@glcaines would you mind taking a measurement from the end of a clamp ring stud to the top of a non-counterweight nut and posting that here? That's what I'm most curious about.

 

[tennmogger]

There must be more to the story about a death from an implied blown up fmtv wheel. The very nature of the assembly is when a few of the 20 bolts are loosened, any pressure in the tire would be dumped. There is no way, IMHO, that most of the 20 bolts could be undone and cause an explosion.

 

[HDN]

There must be more to the story about a death from an implied blown up fmtv wheel. The very nature of the assembly is when a few of the 20 bolts are loosened, any pressure in the tire would be dumped. There is no way, IMHO, that most of the 20 bolts could be undone and cause an explosion.

Those military tires can kill you!

https://www.youtube.com/watch?v=_sS35Nnyy6E I have changed how I handle my tire inflation. Old tires? Get rid of them. It's not worth it.

www.steelsoldiers.com

I ask that subject be discussed there as I'm waiting to see if someone will provide the measurement I'm looking for

 

[glcaines]

After reading about the kid who got a clamp ring embedded in him after trying to service a FMTV rim at 50 psi or so, I'm definitely deflating the tire to zero before trying that (spoiler alert - he was killed pretty much instantly ).

@glcaines would you mind taking a measurement from the end of a clamp ring stud to the top of a non-counterweight nut and posting that here? That's what I'm most curious about.

I just measured mine. I measured the accessible studs on all 6 wheels. They all measured 1-5/16 - 1-3/8 inches, almost all 1-3/8. It sounds like mine match the ones on your truck wheels that haven't been dismantled yet. I should have mentioned that I tighten mine as tight as they will go with my Chicago Pneumatic 1/2-inch impact wrench and then finish with a torque wrench. The 1/2-inch impact wrench doesn't tighten them nearly as tight as the specs require, at least my impact wrench doesn't. I run my impact wrench from the glad hand on my truck. Higher air pressure would likely increase tightening with the impact wrench.

 

[HDN]

I just measured mine. I measured the accessible studs on all 6 wheels. They all measured 1-5/16 - 1-3/8 inches, almost all 1-3/8. It sounds like mine match the ones on your truck wheels that haven't been dismantled yet. I should have mentioned that I tighten mine as tight as they will go with my Chicago Pneumatic 1/2-inch impact wrench and then finish with a torque wrench. The 1/2-inch impact wrench doesn't tighten them nearly as tight as the specs require, at least my impact wrench doesn't. I run my impact wrench from the glad hand on my truck. Higher air pressure would likely increase tightening with the impact wrench.

Thank you very much for checking! It seems that I might not have my clamp ring on tight enough based on that and the air leak I have in my "done" wheel. I'll take more care in tightening the clamp ring with this wheel and make adjustments on the other one I already did and see what happens!

 

[HDN]

So I learned something today that makes me go

First, I now don't think the o-ring was leaking because the clamp ring wasn't tight enough. While reassembling the wheel, I discovered that the compression fitting going to the in-line filter for the CTIS valve split wide open on one flat while I was tightening it. I suspect there's been a hairline crack there that I didn't see when checking for leaks. This leak was slow after all, at about 2.5 PSI lost per week. That said, this is the second failed CTIS brass fitting I've encountered in three days. Does brass age or something, or did AM General get fittings out of the cheap bin 25 years ago?

The main thing I'm mad at myself about is that I found out about that after I tightened everything down 1/16". And that makes me mad because I found out afterward that the new clamp ring nuts I bought from Big Mike's are about 1/4" taller than the original nuts. And I didn't realize that until after I tightened everything down, which took quite a bit of effort with my 1:64 torque multiplier. So I really hope I didn't wreck something

So now I'm trying to decide if I should back all the nuts off, install a new o-ring, and tighten everything up again properly, or leave it as-is. Thoughts?

 

[glcaines]

If it was me, I'd leave it the way it is. I guess I've been lucky - I haven't had any CTIS fittings fail or leak.

 

[gringeltaube]

If it was me, I'd leave it the way it is.

.... unless of course that there is strong indication that the studs have been over stressed/stretched, now (?) The only way to actually confirm is to deflate, then knock out one or two (of the most protruding), and compare its thread pitch against a new stud, or a suitable gauge at least.

 

[HDN]

.... unless of course that there is strong indication that the studs have been over stressed/stretched, now (?) The only way to actually confirm is to deflate, then knock out one or two (of the most protruding), and compare its thread pitch against a new stud, or a suitable gauge at least.

That's exactly my concern, so I pulled the clamp ring off the wheel last night to inspect the studs and o-ring. I used the torque multiplier to crank each of the nuts back about a third-turn, which started really stiff but got easier 3-5 cranks in, then used the DeWalt electric impact to back them out the rest of the way.

Once I got the clamp ring off and vacuumed away the paint and metal dust, I noticed a couple things:

1) I ran a non-locking nut up and down four opposing studs and I didn't observe any signs of thread damage. The same amount of play on the nut was present throughout the length of the studs I checked, so I think the studs are okay.

2) I don't think the o-ring got crushed at all. The o-ring was dirty from the paint debris that fell between the rim and clamp ring during removal, but the o-ring's cross-section was still very round. In comparison, the o-rings I've removed from the rims so far were squished into a triangle. Granted, those o-rings were like that for 10-20 years, so maybe this new one didn't have enough time to squish?

I'm putting in another clean o-ring tonight that I bought as a spare, and I'll keep the one I just removed and figure out how to clean the silicone grease off of it since it still looks and feels usable.

 

[Floridianson]

One thing I did when putting on the ring nuts I used two non distorted nuts across from each either. Tighten them down tight and slow and try to keep ring equal.
Then start to install the distorted nuts and tighten each on down. When you have all distorted nuts torqued replace the two non distorted with distorted. Do not know if it helps you here just trying to get my post counts up or post whoring. Also I use tire soap and NOT glue (spray adhesive). I did a wheel one time and thought I did not get O ring right. Turns out I bumped the small air fitting on the valve stem just enough to slow leak. From then on I took the small one off and put a plug in it. Also one time tire going flat turned out valve stem core was loose.

 

[HDN]

One thing I did when putting on the ring nuts I used two non distorted nuts across from each either. Tighten them down tight and slow and try to keep ring equal.
Then start to install the distorted nuts and tighten each on down. When you have all distorted nuts torqued replace the two non distorted with distorted. Do not know if it helps you here just trying to get my post counts up or post whoring. Also I use tire soap and NO glue. I did a wheel one time and thought I did not get it right. Turns out I bumped the small air fitting on the valve stem just enough to slow leak. From then on I took the small one off and put a plug in it. Also one time tire going flat turned out valve stem core was loose.

You shall henceforth be known as Floridianson the Post Whore

When I started this project I was really worried about how hard it would be to get the clamp ring nuts back onto the studs because they came off so hard! Then I watched a YouTube video which was linked from another topic here about how it's a great idea to chase the stud threads first. I did that on the second wheel and they back off as easily as I described in post #14 here, and they also go on very easily!

So far I've just used silicone grease on the o-ring, which I've used on water filter o-rings for my household filtration system. The M35A3 service manual instructs to lubricate the o-ring before installing it.

For the fittings I've been applying liberal amounts of Permatex pipe thread sealer, which allows for adjustment for up to 24 hours after application. That's nice because tightening the elbows all the way down doesn't allow for proper line-up for the CTIS lines, so it makes lining everything up easier.

I don't think I've ever thought to check valve stem cores for tightness - that's something! I'll be adding that to the list now

 

[Mullaney]

You shall henceforth be known as Floridianson the Post Whore

When I started this project I was really worried about how hard it would be to get the clamp ring nuts back onto the studs because they came off so hard! Then I watched a YouTube video which was linked from another topic here about how it's a great idea to chase the stud threads first. I did that on the second wheel and they back off as easily as I described in post #14 here, and they also go on very easily!

So far I've just used silicone grease on the o-ring, which I've used on water filter o-rings for my household filtration system. The M35A3 service manual instructs to lubricate the o-ring before installing it.

For the fittings I've been applying liberal amounts of Permatex pipe thread sealer, which allows for adjustment for up to 24 hours after application. That's nice because tightening the elbows all the way down doesn't allow for proper line-up for the CTIS lines, so it makes lining everything up easier.

I don't think I've ever thought to check valve stem cores for tightness - that's something! I'll be adding that to the list now

.
Well, that's sad. Didn't realize that I was a Click Whore or a Count Whore either. Just trying to say nice things where appropriate - stand up and say no sometimes - and welcome the new folks and generally have fun here. I have been reading more here than ever before and learning new stuff. Almost choked when I saw the numbers when I clicked my name to see what all the commotion was all about!

 

[Floridianson]

Yea the real pain was more mental. I jacked it up, changed the tire with my spare let it down put tools away. Put soapy water on the wheel / tire in question. Felt real tired and stupid as it is hot here and it was only the valve stem core. If I could have kicked myself I would have and no body around here to do it for me. I will always use the soapy water before I do anything with it on the vehicle. Needless to say I did check all the other valve stems on the trailer just in case and I do check all the vehicles. Also bought a good supply of valve stem cap just to have around. If you did not know they have little legs and can run away.

 

[HDN]

Looking for some advice about another leak that's developed on a wheel I just took CTIS off of. I don't think it's the new elbow or fittings since they haven't bubbled in the leak test.

What I did do in CTIS valve removal is remove the counterweight, which involved removing a nut from the clamp ring. I re-torqued the nut when I reinstalled it and have had a leak ever since. Did I screw up the o-ring taking the one nut off?

 

[glcaines]

Looking for some advice about another leak that's developed on a wheel I just took CTIS off of. I don't think it's the new elbow or fittings since they haven't bubbled in the leak test.

What I did do in CTIS valve removal is remove the counterweight, which involved removing a nut from the clamp ring. I re-torqued the nut when I reinstalled it and have had a leak ever since. Did I screw up the o-ring taking the one nut off?

I'm assuming that you deflated the tire before removing the nut and retorqued the nut with the tire deflated?