bent axle flange?

[WSSix]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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!

[WSSix]

New tires didn't help. That's one more thing checked off the list. Next, I'll swap axles around in a day or two.

[MillerBuilt]

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.
1) I have new wheel adapters that center on what little bit of a hub I have. They fit great.

2) 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. .

3) 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.
Thanks

Based on your previous statements above I have a few comments. The one I have labeled #3 though stands out the most to me. I would start here since that is not normal. For this wobble to occur a few things could be causing this. Axle flange face may not be "true and 90" with the shaft, assuming you run a two piece rotor, your rotor hat may not be "true", or rotor may not be "true". If you run a 1 piece rotor it also may not be true. Then there are the adaptors you are running, are those true in thickness when checked in multiple areas?

Then,,,,, if you are super unlucky, it could be a combination of all the above in what's called "tolerance stacking". 005", .005", .005", 005" starts to add up and wobbles will occur that also translate into vibrations. If you think about the above and the motion it would create if these components are not true and of consistent thickness, it absolutely would create an increasing vibration as the near hub center issue works its way up through the heavy, large o.d of the wheel/tire combo...

I would like to see that video of the rotor wobbling and pushing back on the caliper piston. Also curious what brake package?

Hope this helps.

Jay

[WSSix]

Thanks Jay. My reasoning for removing each component and working my way back to the axle flange was in an attempt to eliminate tolerance stacking and ensure it wasn't multiple issues. I also was checking for flushing fitting between components as I assembled and disassembled.

My adapters came from Motorsport Tech. They are a good company. I haven't measured them beyond putting the dial indicator on them. What I did find is that the wobble is approximately the same 0.006 and in the same high and low locations as the axle flange.

Brakes are C5's so rotor is one piece. Brake kit is from Kore 3 though I supplied the rotors and calipers. I had these same brakes and calipers on the last rear end with a different company's kit. No issues there. I don't really have a way to check the rotor hat for flatness. The rotor does lay flat and not wobble when set on the floor or other "flat" surface.

One other thing I haven't mentioned is I have gone through and cleaned all the mating surfaces and inspected them to make sure I don't have any mate up issues that could some how create a stacking issue. I've sanded down the back of the wheel with a sanding pad and 320 grit for instance just to see if there were any high spots. I noticed nothing out of the ordinary. The high and low spots from the axle flange translates out to the rim edge.

I'm about to go out side and start working on swapping the axles. I'll see about getting a video when I do that. I'll have to remove the brake kit which I think this will give me a better view of the axle flange to determine is the face is simply not true or if the shaft is bent which is throwing off the flange.

Thanks!

[MillerBuilt]

No doubt you are taking a very thorough approach to solve this issue, and all your parts selections are solid too. I feel for you on this. I hate problems like these. Everything sure does seem to point in the axles direction though..

I take it you have a 12 bolt since you are swapping axles. This will certainly prove it out if the wobble now presents itself on the opposite side that you change it to.

Let us know what you find.

Jay

[WSSix]

At this point, I don't know how else to solve this issue without being thorough in my methods. Nothing is obviously the culprit. I'm also still concerned I may have more than one problem.

I played around with the car today but didn't swap axles yet. With the new tires on the car, the wobble and vibrations weren't as pronounced. So I decided to swap wheels front to rear instead of just going straight to swapping axles. The low speed vibrations at 30 mph are pretty much gone with the front wheels on the back now. I decided I better try 65 to see how it felt there considering that's where I get the vibrations when driving the car and not just sitting on jack stands. I was only going to 30-35 on jack stands because that's all I needed in order to get the vibrations.

The vibrations are definitely there at 65. 55 feels ok but 65 is very different. I got the vibrations with the wheels on or off the car. This leaves me confused in all honesty. My thoughts at this point are to pull the axles and run the car up to 65 with just the differential in place. If I get vibrations, it's in the driveshaft/pinion angle. If not, axles. I have a Detroit TruTrac differential. I'm going to read the manual as well, but does anyone know if running it without axles in place will cause a problem?

I've gone through 6 degrees of sweep with the pinion angle in 2 degree increments previously. Nothing changed one way or the other from what I could tell. If it's driveshaft/pinion related, I'm going to be more lost than I am now, lol.

Jay, I have a modified 8.5" 10 bolt with Torino bearing ends welded on.

Also, before I pull the axles, I'll most likely go drive the car with the wheels swapped front to rear. I want to see if the vibrations also move. While I had the wheels and tires checked and they told me the wheels are good. I'm not sure why I don't get the vibration with the front wheels but I do with the rear wheels.

The one good thing from today is that I've determined I can indeed run a 9.5" rim and 275 tire on the front without too much trouble. Yes, minor inner fender work and lip rolling will be needed but I already planned on that anyway. I'll start the hunt for some factory 9.5 rims soon.

Thanks

[SSLance]

Man I feel your pain chasing down vibrations...been there done that. I'm sure you have but just in case, make sure there isn't any play in your rear axle bearings. I've found pushing straight up and down on the raised off the ground tire with your hand is the best way to feel if there is any play at all. A very small movement of the bearing will vibrate..believe me...

Sweet about the 9.5s on the front, been there done that too!! :D

[WSSix]

Thanks Lance. There is very minor play in the axle bearing. A few thousandths at best. It's if I twist side to side though while grabbing the outside of the tires. I can't get any up or down movement. No in or out movement either.

[WSSix]

Well, it appears it is in the drive shaft or pinion. I get the vibration at 65 with no axles in the car. After this happened I decided to get under there and really be specific about what I felt and could move. I get a little slop in the u joint. It's so minor that I don't see how it could be the issue but I have a new u joint on order all the same. I'll get it put in today I hope. This is annoying, lol.

[WSSix]

How much does 3 in lbs matter?

When I built the rearend and set up the gears, I crushed the sleeve and went over the spec by 3-4 in lbs. Could this have anything to do with my vibration?

I ask because I could hear a noise in the rearend at the front under the pinion and it did feel rough. However, the pinion doesn't have any play. I also have no metal shavings or anything in the gear oil. I drained it last week when working on the car to check. This roughness and noise happens with speed. At idle in first gear, I hear or feel nothing. At idle in fourth gear, I hear and feel it. This is with the rear off the ground so the tires can spin freely.

I'm just looking at everything since I'm not getting far with this vibration issue. I've determined that it's definitely in the driveshaft and pinion area. I still got the vibration with no axles in the car and only the driveshaft in place.

New u joint didn't change anything.

Thanks

[WSSix]

Well, I've found something new that might be an issue. I have too much delta at the u-joints. It's 5* at the front u-joint and a little over 4* at the rear u-joint. The transmission is lower than the rear end so I'm going to raise it with shims to see if that will flatten out the angles at the u-joints. Might need to pull a shim out of the rear end too but that's no big deal either.

I don't see how this could be the issue necessarily though. Before I did the suspension work, the rear sat lower than it does now due to the worn out factory springs. That would have made the angles worse. Yet, I had no vibrations then.

[light bulb!] :ohsnap: As I'm typing this I just remembered the front end used to sit higher too though. I've brought the front end down with the coil overs compared to worn out factory coil springs. That could be the reason I didn't have the issue when I first did the engine and transmission swap. Yep, going to raise the tail of the transmission.

Oh, and I have 1-1/2 inches of yoke shaft sticking out of the transmission currently. I still have plenty of engagement with the tail shaft. Could this be too much though?

Thanks

[SSLance]

I've had my best success eliminating driveshaft vibrations by getting the tail shaft of the trans parallel to the pinion yoke of the rear end. This lets both U-joints operate at exactly the same speed. It doesn't really matter which goes up and which goes down, just make sure they are both parallel to each other.

My trans points 3.5* down and I have my pinion pointing 3.5* up and she's smooth as butter...

[Che70velle]

Trey, I'm inclined to believe that it has something to do with the roughness that your feeling as you turn the pinion. You used a new crush sleeve, I'm sure. When you reached the inch Lb. measurement, and it was a tick too much, did you back it off any?
How many inch lbs. did it take to turn the pinion with a socket on the pinion nut? You have to check that number BEFORE you put the carrier back in...your checking pinion preload only, and the carrier/ring gear will throw this number way off.
It sounds like you have too much preload on the pinion, with the roughness your describing. I hate to say it, but you'll probably end up setting the pinion up again, which is a pain. Hopefully I'm wrong.
I have another one to do for my nephew. He just bought a 3.90 gear set for his silverado.

[WSSix]

I FIXED IT!!!!!!! It was so simple too. I can't believe I missed it multiple times. Oh well, such is life. The one u-joint strap was not holding the cap fully. As I mentioned earlier, I replaced the rear u-joint due to it having a little bit more play than I thought was correct. Turns out that play was the cap moving and I just didn't see it. I noticed it this time though. I took both straps out cleaned them and filed the flats down so that I was certain no burrs or slight deformation would keep it from bolting down fully. I put everything back and the play was greatly minimized because the cap was no longer moving. Took the car out and there's nothing but smoothness.

I'm still planning on a new driveshaft as I need about a 3/4 inch longer shaft. I'll do it when I do the transmission and engine later this year.

This was such a battle and pain in my ass that it really had me questioning if I should be doing anything related to cars aside from drive them. Now I can finally move on to all the other things I need to address on this car.

Thank you all for the replies and suggestions.

Scott, to answer your questions. Yes, new sleeve. I'm going from memory but I want to say 25-26 in lbs to rotate pinion. I do remember it was 3-4 in lbs over. Only pinion was in place. No carrier. I didn't back it off any. Pinion rotates smoothly by hand.

I posted the 3 in lb question over on NastyZ28 as well. There's a gentleman that posts regularly, Big Gear Head, that sets up lots of rearends. He really knows his stuff. His replies helped me rule out that being the issue. Still not sure why it's making the noises though. It could be the TruTrac or simply the gears running through the oil. It was very interesting to listen the gears and carrier rotate without the axles in place. The gears churning up the oil is rather loud inside there.

[WSSix]

I've had my best success eliminating driveshaft vibrations by getting the tail shaft of the trans parallel to the pinion yoke of the rear end. This lets both U-joints operate at exactly the same speed. It doesn't really matter which goes up and which goes down, just make sure they are both parallel to each other.

My trans points 3.5* down and I have my pinion pointing 3.5* up and she's smooth as butter...

I'm now sitting about 2.5* +/- 0.5* transmission down and pinion up now. I'm still a little concerned about the delta at each joint but it doesn't seem to be affecting anything now that I've got the vibration fixed. Thank you, Lance.

[Che70velle]

I love simple fixes! You should make a Burnt mountain run, and bring it by!

[SSLance]

Woo Hoo! I hate stupid crap that can drive you crazy like that but we've all been there done that before and can all empathize... Feels good to figure it out though right?

[WSSix]

I plan to once the weather cools off a little more, Scott. No AC currently, and I'm busy on weekends for a while. I intend to get up that way soon though. I still need to see your Chevelle too.

It does feel good, Lance. I was really starting to pull my hair out over this.

Thanks!