RCV 300M Rear Axle Cone Washer Issue

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Gerrha

Gerrha

Joined
Jan 2, 2024
Threads
30
Messages
200
Location
Houston, TX
I purchased a set of RCV 300M rear axle shafts almost two years ago and am only now installing them. Everything went well up to the final step of torquing the 6 stud nuts. What I discovered is that the nut runs out of threads on the stud before the cone washer has been tightened properly. My first set of studs are OEM 90116-08325. Because of the problem, I decided to try Trail Gear's hub stud kit using ARP studs just to see if there is a difference. Same problem.

In my view, the only thing that would cause this to happen is if the RCV flange that comes with the axles is machined about 2-3 mm short in thickness. Sadly, I no longer have my old, removed, OEM rear axles to check.

I tried to call RCV to ask and no one answers their tech line. I filled out their tech submission form but have not yet received a reply.

The photo below shows what I have described. The studs shown are the ARPs. You can see that the washer's thickness is insufficient to cover the exposed unthreaded portion of the stud, which means the nut will run out of thread before the cone washer has been tightened correctly.

I was wondering if anyone else has faced this same issue?





IMG_6946.webp
 
IIRC, the studs have different length threads on both ends. Did you try turning the studs around?
 
I have tried both ways with the OEM studs. With the long end screwed into the hub all the way, the situation is just like the above photo. When the short end is screwed into the hub, it is slightly closer, but I still cannot reach the 25 ft-lb torque without the nut bottoming out on the unthreaded part of the stud. If that flange was slightly thicker it would be fine.

I sort of remember when I ordered these, there was a big delay and someone at RCV mentioned they were redoing these axles for some reason, but I do not remember why. I wonder if it was this issue.
 
Belmetric has a good selection. You could venture into threading the the unthreaded area of what you have. I run RCV kits at both ends but I think my studs are from Front Range off-road.
 
baldilocks said:
Belmetric has a good selection. You could venture into threading the the unthreaded area of what you have. I run RCV kits at both ends but I think my studs are from Front Range off-road.
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This seems a little weird to me possibly having to get different studs (again) or threading them. I wonder how thick the OEM axle flange is compared to the RCV flange I have.
 
I had problems with RCV products we won’t discuss here. We believe but they disappoint in the field of precision. Let’s hope the advertised strength is what it’s supposed to be. You can get around this minor issue.
 
baldilocks said:
I had problems with RCV products we won’t discuss here. We believe but they disappoint in the field of precision. Let’s hope the advertised strength is what it’s supposed to be. You can get around this monir issue.
Click to expand...
I could solve the tightening problem by using a second washer to give some additional thickness, but that might open the door to other problems with strength etc. I suppose I could go to a machine shop and add some additional threading to the studs as Baldilocks suggested, but yikes! This should have been done and wrapped up by now...
 
Quick numbers,
RCV flange thickness, 0.360"
Factory flange thickness, 0.360"
Cone protrusion when torqued, 0.060"

I didn't get the shoulder protrusion from the hub as it is below the surface of the cone washer.

Something is not adding up there.

Also. When you get this figured out, make sure to add some grease to the splines at the end of the axle and flange.

20260403_131645.webp
 
See the two photos of drawings with my actual measurements. Both the OEM and the ARP studs are screwed into the hub to the end of their threads, so there is no additional depth for them to go into the hub.

IMG_6950.webp


IMG_6951.webp
 
Those are all very similar numbers to what I have.

I cannot remember if the shoulder on the stud goes into the hub, but seems like I recall that it does a bit? This would also make some sense as all of our dimensions are matching up.

Maybe someone else has theirs taken apart this far. I just re-assembled mine last night and don't want to take it apart unless you don't get any reply.
 
ThreeEyedBandit said:
Those are all very similar numbers to what I have.

I cannot remember if the shoulder on the stud goes into the hub, but seems like I recall that it does a bit? This would also make some sense as all of our dimensions are matching up.

Maybe someone else has theirs taken apart this far. I just re-assembled mine last night and don't want to take it apart unless you don't get any reply.
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You are correct. Our numbers are very close. That does not solve the problem though. Assume the flange thickness is as you said, 0.36". The cone washer protrudes 0.06" from the flange face. I measured 0.60" of no thread length on my studs. That leaves 0.18" of no threads extending past the cone washer. The washer is not 0.18" thick, thus the problem.
 
Gerrha said:
You are correct. Our numbers are very close. That does not solve the problem though. Assume the flange thickness is as you said, 0.36". The cone washer protrudes 0.06" from the flange face. I measured 0.60" of no thread length on my studs. That leaves 0.18" of no threads extending past the cone washer. The washer is not 0.18" thick, thus the problem.
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Yes, I follow you there. With the numbers matching there is something else going on since the numbers match.

The shoulder on my studs go approx 0.150" into the hub, which account for almost all of the gap. Then ~0.015" of compressed gasket, then washer and nut.

How far does the shoulder of your stud go into the hub? Even better. If you install a factory stud and bottom a nut on it, how much gap is there?

This scribe line is just at the surface of the hub when the stud is installed

1000037839.webp
 
ThreeEyedBandit said:
Yes, I follow you there. With the numbers matching there is something else going on since the numbers match.

The shoulder on my studs go approx 0.150" into the hub, which account for almost all of the gap. Then ~0.015" of compressed gasket, then washer and nut.

How far does the shoulder of your stud go into the hub? Even better. If you install a factory stud and bottom a nut on it, how much gap is there?

This scribe line is just at the surface of the hub when the stud is installed

View attachment 4115245
Click to expand...
It sounds like your hubs are counter-bored, so the non-threaded portion of the stud extends into the hub by 0.15". That would account for the problem I am having. My hubs are brand new OEM part number 42450-69016. The parts diagrams show the correct part to be 42450-69015, but 42450-69016 is shown to be the newer replacement. Possibly, this is the problem
 
Looking into the threaded hole there is no counterbore, just some lightly smashed threads. As far as I know the oe studs came out last week when they go replaced.

How tight are you installing the studs?

At least this all confirms that the RCV stuff and hardware are correct.


Otherwise. No more ideas, need to get my rig back together.
 
The OEM studs are finger tight, but the ARPs with the hex heads were installed very tight. I agree that the RCV items seem ok. I likely will have no other option than using two washers in order to use up the unthreaded portion.

However, I do appreciate the efforts you took to help resolve this! Thanks
 
NeverFinis said:
Can you take the RCV flange off and see if the ARP studs and the OEM studs fit fully through the RCV flange?
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Yes, I have done that. The studs screw into the hub all the way to the end of the threads and this does not matter if the short or long end is screwed into the hub indicating there is sufficient thread depth in the hub.

However, in looking at the photo above submitted by ThreeEyedBandit, I noticed something significant. Attached below is a similar photo for one of my new OEM studs, part number 90116-08325. A simple qualitative look-see shows a clear difference. The unthreaded length of his stud is much shorter than the unthreaded length of my stud. This is the problem.

How could this happen?

IMG_6952.webp
 
The RCV flange is designed for large cone washers, as well as bigger studs. The cone washer is sitting to low in the hub, hence why you have no thread left on the stud.

Cheers
 
Thanks!

That might very well be the problem. But now I am looking at solutions. I am proceeding in 2 directions. One is getting the correct die for the studs with the thought of increasing the threaded length of the studs I have. The second direction is trying to buy studs with the dimensions that will work from Bel Metric.
 
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