bent axle flange? - Lateral-g Forums

**WSSix** · #1 08-02-2016, 06:50 AM

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** · #2 08-11-2016, 03:37 PM

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** · #3 08-13-2016, 08:58 AM

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!]

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 · #4 08-13-2016, 10:25 AM

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 · #5 08-13-2016, 01:25 PM

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** · #6 08-13-2016, 03:10 PM

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** · #7 08-13-2016, 03:14 PM

Quote:

Originally Posted by 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...

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 · #8 08-13-2016, 04:30 PM

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

SSLance · #9 08-13-2016, 07:09 PM

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?