bent axle flange? - Lateral-g Forums

**WSSix** · #1 07-25-2016, 07:06 PM

I'm still fighting a vibration issue with my car. I've slowly been testing areas and making adjustments. Here's where I'm at now. I have new wheel adapters that center on what little bit of a hub I have. They fit great. They helped the vibrations but didn't eliminate them. The wheels and tires have been balanced using a road force machine. They were out and that helped again. Again, however, it didn't eliminate the vibrations. I had the driveshaft balance checked. It's good. While I had the car at the driveshaft shop, the tech noticed the passenger side rear wheel vibrated/wobbled/bounced around. So I've currently been concentrating my efforts there.

I've had the rear of the car up and have been checking that right rear axle. It's not the wheels as I can swap wheels side to side and the wobble is the same regardless of the wheel. I bought a dial indicator and am getting about 0.035" wobble on the outer rim lip. I've been able to trace this back to the axle flange itself. I've identified high and low, or in and out, using that same dial indicator. The difference is about 0.006". Can this be the issue? I can remove the wheel from the car and drive it up to about 30-35mph while on jack stands and there's no vibrations in the car like there is when the wheel is on. I can also see the rotor wobble as it rotates and it pushes the caliper in and out as well. There's definitely an issue with the flange and not the wheel balance that's vibrating the car. So it feels like this is the issue. But I don't feel any vibrations while driving the car until 60mph. I would think if it's the wheels I would feel something always. I wonder though if the shocks are able to control the vibrations until 60mph since it's not a serious wobble. Think that's plausible? I'm going to adjust them tomorrow and see if I can get the vibrations to change when they come in or something.

The concern I have is if this is the flange, how in the world did this happen? These axles are brand new, custom units from Moser with a few hundred miles at most on them. There's no way their tolerances are that lax. That's terribly out of round for a brand new machined part. The high and the low points on the axle flange are not 180* apart. It's more like 150*-160* at most. I've been fighting this issue since the rear end went into the car. I haven't hit a curb or anything. I just didn't expect it to be axle related since I was doing other work at the same time and these axles fit just fine without fighting them. I'm just not sure what's going on any more with this vibration issue. It's driving me bonkers.

Thanks

TheJDMan · #2 07-25-2016, 07:39 PM

Seems to me that you have answered your own question. You have a bent axle and if it is new you need to contact Moser about getting it replaced ASAP. Did you purchase the complete rear end from Moser or just the axles? Either way, it may have been damaged in shipment.

**WSSix** · #3 07-26-2016, 05:39 AM

that's what I was thinking, too, Steve. I just thought I run my tests and observations by others to see what they thought.

I'm not sure Moser will help. I had to take the axles to a machine shop in order to get the access hole drilled into the flange so I could bolt the axles in. I don't see how the machine shop could have damaged them, but I'm sure Moser will wash their hands of the situation since work was done to them after the fact.

I just got the axles from Moser.

Thanks

**WSSix** · #4 07-26-2016, 11:04 AM

Changing the shock settings didn't change anything in terms of the vibration.

I also spoke to Moser. They said 0.004-0.005 is typical but that it has to be measured on a lathe with the shaft between centers or on V-blocks in order to be accurate. This makes sense but at the same time, my wheel wobbles. I can take a video and show it wobbling. So if it's not the flange or axle shaft, what else could it be?

The person who welded the Ford bearing ends onto my housing used the alignment tool that puts the axles in line. Also, installing and removing the axles is easy as expected.

Thanks

SSChef · #5 07-26-2016, 11:13 AM

I had a similar situation and it turned out to be the wheel hub register to hub register. One axle was off by .015 and the wheel would not fit perfectly on the axle hub. It would be crooked when you tighten the wheel. I have read that you are running spacers. Are they hub concentric?

**WSSix** · #6 07-26-2016, 02:40 PM

Yes, that was the reason for needing new adapters. The new axles had very little hub protruding through the rotor so I needed an adapter that was squared on the backside so that it could engage the hub. The front side of the adapters fit the wheels well. The wheels haven't changed through any of this.

Unless anyone has some better ideas, I think what I'll do is have the wheels balanced one more time with emphasis on checking for rims being true and tires being good. I just had them balanced last time. I didn't specify anything beyond that. I'm expecting them to come back as being just fine.

Then, I'll swap axles side to side and see if the wobble follows. If so, I guess I'll have to order a new axle. While the axles are out, is there anything in particular I should do or look for to help determine a cause to the issue?

I hate throwing parts at a problem. I'd rather try to learn from the issue

Thanks!

bretcopsey · #7 07-26-2016, 06:16 PM

Did you measure runout on the bare axle flange or with the rotor in place? If with the rotor in place, wondering if the axle flange is too large diameter and not allowing flush fitment of the rotor?

**WSSix** · #8 07-26-2016, 06:46 PM

I measured on the axle flange. The rotor does sit flush to the flange. That's a good thing to remember when doing a rear brake conversion though. I have no way to measure run out on the rotor itself unless I move it to the other axle.

Basically, what I did was work my way back from the wobbling wheel to either where the wobble ended or to where I had nothing left to remove. That turned out to be the axle flange.

Thanks!

MeanMike · #9 07-27-2016, 06:02 AM

If it comes to the axle and the flange only has .006" runout and is otherwise fine, I would knock the studs out and have a machinist take a light face cut to square it. He would need to check the bearing surface for runout with the axle between centers first to ensure the shaft portion isn't bent.

**WSSix** · #10 07-27-2016, 11:42 AM

I've thought about that as an option, too, Mike. It's hard to tell with them in the car but I'm afraid it's not just the face/surface. I'll check as I move further along.

Tire shop said they are balanced and the rim is good. The tires aren't round any more though. I feared this since the car did sit for so long with these tires on it. I just never noticed any noise or low speed issues. I was planning to buy new tires soon. I just ordered new Dunlop Direzza DZ102's for the rear. They'll be here by tomorrow. I'm waiting on the front because I want to see if I can go with a 18x9.5 rim on the front, too.

Thanks!