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Sun Sep 01, 2024 9:26 am

I installed a new set of plus one inch trailing arms on my Rat Rod Trail Rail. The CV's are the Type 2's 100 MM and they were race prepped/polished. I've been running them for quite a while now with no issues.

Now, when I first start up and take off, there is a clicking noise from the rear end. It increases with speed and then after a few minutes goes away totally. It won't do it again for the rest of the day. Any ideas?

Sun Sep 01, 2024 9:54 am

Anytime I have had a clicking sound in the rear of an IRS car. It's always been the CV joints.
Maybe take um loose and check them for the proper amount of lubricity.

Sun Sep 01, 2024 7:50 pm

Are the CV joints lubed sufficiently?
Are they clocked appropriately ?
Could also be wheel bearing, but that might be more evident when turning Left or Right.

Sun Sep 01, 2024 9:49 pm

I'm going to take that axle off and check the CV's. I took it all apart to install longer arms and it wasn't clicking before so I probably missed something. Truthfully, I'm not sure I clocked that side. I know I did the other side but I'm not sure about that side. So I'll pop it off and do it again.

Deep down, I knew I was going to have to do that but I was hoping that somebody would be able to say "Oh yeah. I know what that is. The Thermogulator isn't Bopulating properly. A tack hammer gently tapping on the end of the Diselectrocutor will fix it in a jiffy". Oh well.

Mon Sep 02, 2024 7:57 am

Typically you would hear the clicking of a bad cv when turning. At least all mine that have gone bad the first indication was the clicking when turning but not in the straights. And that it goes away makes me think it’s not your cv’s. Other things might be a rock stuck in your tire treads, or pieced of metal, like a spring clip or brake retainer clip inside the rear drums.

Mon Sep 02, 2024 8:03 am

Hmmm. Whatever it is, it goes away after a few minutes. I'm going to pop the axle off and check the clocking on it. I may have screwed that up.

Mon Sep 02, 2024 9:59 am

I had a rock in the drum once it would make a click clack sound then go away. After a few miles of that the stone got small enough to jamb in the shoe, then the brake would drag and a spring pinging noise brake would release. Back to the click clack sound brake drag and spring noise.

Mon Sep 02, 2024 1:48 pm

Could be the wheel bearings.

Mon Sep 02, 2024 3:27 pm

Did you replace the shafts with longer ones, or are they stock length?

Mon Sep 02, 2024 7:49 pm

I don't think it's the wheel bearings or brakes because I can yank on the steering brake handles and nothing changes. I'm pretty sure it's the CV's. The drive axles are torsion types but stock length. I only went one inch over on the length. The clicking noise is not axle spline slippage.

Tue Sep 03, 2024 6:44 am

So stock length axles will hold the inner star races of the cv joints closer together. This causes the balls to extend further towards the outer edges of the slots in the cages. The balls may be just kissing the cages, or at least bumping into them. When you use more plunge on the cv joint (a shorter than ideal axle will do that), you effectively loose articulation, because the balls can only travel so far inside the slots in the cage.

Jack up the back end and rotate the wheels by hand. Watch the axles. If you see them oscillating left to right (3 cycles per revolution), you are at the limit of what the cv can do. You can clock the CV joints to balance out the thrust forces on the axle. That will help keep it from plunging to the point of the balls hitting the slots in the cage. When not clocked and pushing the limits of these kind of cv joints, the noise often heard is the balls hitting the cage when the axle thrusts the inner star to the limit of its travel.

Do the rotate the wheels when jacked up test and report back. You may need slightly longer axles.

Also, are the axles stock style shouldered or aftermarket floating spline?

Tue Sep 03, 2024 7:36 pm

I've rotated the wheels and they're quiet. No noise or bumpy feeling. It only happens under a load and it goes totally away after a few minutes. The axles are aftermarket floating splines type, no shoulders. I am about 98% sure that I did not clock the CV's on that side. I'll take them apart in the next few days and see what's up.

Wed Sep 04, 2024 8:38 am

Vanapplebomb wrote: Did you replace the shafts with longer ones, or are they stock length?

My first thought as well.

Maybe time for some straps

Wed Sep 04, 2024 8:47 am

Possible, the joints don't like where they are positioned now. You added an inch but that's the arm, right? In the axles perspective it's more like an inch(maybe a smidge more at some backward angle.
This is total arm-chair mechanic stuff here, but I wonder if you're at the edge of your travel and when you first take off for the day you notice it because the grease has settled in the joint. As soon as you take off it starts lubricating and goes away, but it's still there. Clocking wrong will also get you to that point as well. I had the same problem recently when I installed a cv pointing in the right direction. Meaning, the face that normally faces the wheel or the transmission was facing the axle. Easy to mess up if it's late in the day and your in a hurry not paying attention.

Wed Sep 04, 2024 8:50 am

Vanapplebomb wrote: Jack up the back end and rotate the wheels by hand. Watch the axles. If you see them oscillating left to right (3 cycles per revolution), you are at the limit of what the cv can do.

Wulfthang wrote: I've rotated the wheels and they're quiet. No noise or bumpy feeling…

:wink:

Try the test again and report back with the results.

Wed Sep 04, 2024 9:02 am

ORANGECRUSHer wrote: Possible, the joints don't like where they are positioned now.

Yeah, that is my thinking as well. Plunging the cv joints farther results in a loss of articulation. You can have full plunge, or full articulation, or a mix of the two, but it is a trade off, and you can’t have all of both. Longer arms with stock length axles will reduce the amount of available articulation because the balls will be riding further towards the edges of the cage slots.

Floating axles may explain why it goes away after a while of driving, and while only under loads. Takes a little bit for the inner stars to find where their home is on the splines so the balls won’t hit the cages, and those stars won’t move easily the splines while under load.

Wed Sep 04, 2024 9:04 am

That's interesting way to troubleshoot that. I'm going to have to remember that. Funny, I didn't catch it the first time i read your post so I'm glad you reposted it.

Wed Sep 04, 2024 9:06 am

When was the last time the wheel bearings were replaced? Are they tight in the housing at room temperature?

Wed Sep 04, 2024 10:09 am

ORANGECRUSHer wrote: That's interesting way to troubleshoot that. I'm going to have to remember that. Funny, I didn't catch it the first time i read your post so I'm glad you reposted it.

I found that when setting mine up and experimenting with how much I could push things. Lot of trial and error and observation. Learned a lot in the process though.

Wed Sep 04, 2024 7:41 pm

The wheel bearing and spacers are brand new. The CV's have maybe five hundred miles on them. The clicking is very soft, almost not noticeable and only lasts for about five minutes before vanishing completely. I'm pretty sure I did not clock the CV's on that side so that makes me pretty sure it's a ball clicking until it warms up. I'll take them apart in the next couple of days and clock them. Thanks for the tips.