Moparchat - Home of MOPAR enthusiasts worldwide!



Go Back   Moparchat - Home of MOPAR enthusiasts worldwide! > Technical Forums > Performance Talk

Click here to search for Mopar cars and parts for sale.


Reply
 
Thread Tools Display Modes
  #1  
Old 09-12-2001, 04:22 PM
road chicken's Avatar
road chicken road chicken is offline
Inactive User
 
Join Date: Feb 2000
Location: WI
Age: 58
Posts: 818
Default Axle shaft ?? Help guys

Ok guys and gals- after a summer of chasing,( and catching a few of) the "Wild bikini" I have returned
I have this annoying vibration in the car I suspect is the axle shafts- I have measured the flanges and they have little to no runout. The axle shaft has a bow of .040" to it,(.020 to make it straight). is this a likely culprit?? The vibration is similar to a harmonic until you hit 85 then it turns steady.
Reply With Quote
  #2  
Old 09-13-2001, 06:22 AM
Hammer 74's Avatar
Hammer 74 Hammer 74 is offline
Inactive User
 
Join Date: Feb 2001
Location: Arlington Hts, IL
Age: 56
Posts: 548
Default

You said the flange has no runout but the axles have .040/.020. Are you checking it while holding it by machined surfaces (splines and hub), or just spinning it by the shaft. If the axle was bent you may be able to multiply/magnify the amount of runout at the flange by checking side to side runout of a rim at the outer edge with it bolted on the car. How to mount an indicator is a problem and the rim needs to be straight and true.
Are all of your rims balanced? I ask because an axle is such a small diameter spinning that I am not sure what sort of vibes it could be producing. I would think it would be a vibe that gets worse as you go faster. 85 mph with a 3.55 gear and 27 inch tire is spinning the driveshaft 3750 rpm and the axle would be only 1050 rpm. I have spun large things in a lathe faster than that and they were not balanced very well with only a small amount of vibration. Just thinking out loud.
Reply With Quote
  #3  
Old 09-13-2001, 12:39 PM
road chicken's Avatar
road chicken road chicken is offline
Inactive User
 
Join Date: Feb 2000
Location: WI
Age: 58
Posts: 818
Default

I checked the flanges with the axles installed in the housing. But found the bow when I had new bearings installed. the mech I talked to said as long as the flanges were true,( +/- .002) I should be fine. The vibration has a definate difference between light and heavy loading on the drivetrain( part throttle and to the floor), but only at he higher speeds. It will come and go at a set rate- increasing in frequency the faster it turns. For the record- 3.23 sure grip with 15X8 mag 500 rims,( new aftermarket) and 255-60-15 ( dunlop gt qualifiers) balanced. the driveshaft has also been balanced. It is still there when I run it up to 85 and depress the clutch and let the drive train " coast". It does seem to get more intense as the components warm up to operating temp- what are the odds it could be the tires??? I had the axles mounted in a lathe when I checked the bow of the axle.
Reply With Quote
  #4  
Old 09-13-2001, 12:53 PM
Doug Wilson Doug Wilson is offline
Inactive User
 
Join Date: Aug 2001
Location: Sheridan, Oregon
Age: 79
Posts: 2,510
Default Axle?

When you have an out-of-balance tire/wheel condition, the vibration will usually "tune" between certain speeds, it will shake between, say 40 and 60 MPH and "tune out above and below that....see next post
Reply With Quote
  #5  
Old 09-13-2001, 12:58 PM
Doug Wilson Doug Wilson is offline
Inactive User
 
Join Date: Aug 2001
Location: Sheridan, Oregon
Age: 79
Posts: 2,510
Default axle2

The first thing I would do now, is to get to a high quality tire shop and have them check roundness of the tires and also roundness of the wheels whith a dial indicator. Any good tire shop can do this without removing the tire & wheel assemblies from the car. to check both rears shouldn't take more than 30 minutes, including setup time......see next post
Reply With Quote
  #6  
Old 09-13-2001, 01:01 PM
Doug Wilson Doug Wilson is offline
Inactive User
 
Join Date: Aug 2001
Location: Sheridan, Oregon
Age: 79
Posts: 2,510
Default axle3

Also, you may know this, but just in case - you feel rear end imbalances in your butt and front wheel imbalances in the steering wheel. I agree with Hammer - it is probably not your axles.
Reply With Quote
  #7  
Old 09-13-2001, 01:05 PM
Doug Wilson Doug Wilson is offline
Inactive User
 
Join Date: Aug 2001
Location: Sheridan, Oregon
Age: 79
Posts: 2,510
Default axle4

If the tire shop says that they can do it without a dial indicator - by "eyeballing" it or checking them off the car - you need to get another tire shop. It needs to be checked on the car, and that will also show any effects that the bent axles have. I really don't think that's the problem - but....I could learn something new here.....from the open (empty?) mind of Doug
Reply With Quote
  #8  
Old 09-13-2001, 02:05 PM
road chicken's Avatar
road chicken road chicken is offline
Inactive User
 
Join Date: Feb 2000
Location: WI
Age: 58
Posts: 818
Default

I can check the wheels at home on the jack stands. I have the equipment there for that. I'll have to find the proper indicator to do the tires. It is very frustrating because it shakes thru the car like wet dog ( start at one end then works to the other)- but I can't tell which end it is originating from( back or front). I know the tires tend to tune in on a certain speed for imbalance. A weird part about this is- when it is dead cold there no vibration-none- but as it warms up it starts and gets worse. The tire wheel combo has never balanced to my satisfaction. I have done it X2 and had two different tire places do it also- high speed and low speed. Hell I've got @ 3oz at one place on one tire alone. The balancer will tell me it's OK then re-spin it just to check and it's out again,( the balancer is checked good). I'm really starting to figure on just dumping the tires because everything I'm hearing here is aiming,( and substantiating) my suspicions of them.
Reply With Quote
  #9  
Old 09-13-2001, 04:06 PM
Hammer 74's Avatar
Hammer 74 Hammer 74 is offline
Inactive User
 
Join Date: Feb 2001
Location: Arlington Hts, IL
Age: 56
Posts: 548
Default

Most good tire shops would never put that much weight on to balance it. I would mark the tire on the rim and dismount it and check the rim for balance and if it is good then move the tire 90 degrees off the mark when remounting it and check again and so on. I have 2 custom offset 8" rallye wheels that a friend of mine checked before I mounted tires and they were true and round and to both of our surprise perfect balance. Whoever did the rims had welded extra on them to balance them. One spot has a non structual weld clump. We mounted some BFG T/A's on them and one needed no weight and the other has the smallest weight on them. He said to me this is very rare to have a perfect rim and near perfect tires.
I have checked wheel/tire out of round with (dont laugh) two floor jacks and 2 4 by 4's. One jack under each side of the axle. lift the car up over both 4's and lift one side to clear that one and the other just barely off the other. With a light behind the tire, spin it and you will visually see out of round. It may even touch in one spot. The eye can notice small gap changes easier than large ones. Just an idea.
Reply With Quote
  #10  
Old 09-13-2001, 04:26 PM
road chicken's Avatar
road chicken road chicken is offline
Inactive User
 
Join Date: Feb 2000
Location: WI
Age: 58
Posts: 818
Default

Hmmm, now you got me thinking. There are red dots on each of the tires. I was told that it marks the heaviest point of the tire. They are mounted so the red dots are in line with the valve stems. Is that right or does the dots show it the lightest part of the tire?
Second Assuming all else is good and the tires are the fly in the ointment here, what good would it do to turn the tires 90 deg on the rim?
Reply With Quote
  #11  
Old 09-13-2001, 04:39 PM
Hammer 74's Avatar
Hammer 74 Hammer 74 is offline
Inactive User
 
Join Date: Feb 2001
Location: Arlington Hts, IL
Age: 56
Posts: 548
Default

If the rim has a heavy spot and the tire has a heavy spot and if they are mounted in the same orientation then there is a real heavy spot; lots of weights. The dots I am not sure about but with them at the stem, you have a starting point for better balanceing. I have heard of people moving the tire on the rim and rechecking balance to find the optimum pre weighted balance. Then you have the least amount of weights on the rim.
Reply With Quote
  #12  
Old 09-13-2001, 06:45 PM
Stoga's Avatar
Stoga Stoga is offline
Moderator
 
Join Date: Jan 1999
Location: WV
Age: 65
Posts: 8,586
Default

This is just a thought, but how old are the tires? Have they had a lot of full throttle launches on them? I only bring this up, cause many things have been checked with no success. but is it possible you have a busted belt in one of your rear , or possibly, front tires? It's usually pretty easy to check, spin the tire with the car jacked up, and watch the tread pattern as it rotates. If there is a bad or broken belt, there will be a section of the tread that is no longer in alignment when you spin the tire. Sometimes this is real obvious, other times it can be hard to see. But at least look, and eliminate the possiblity. Usually if I have a car that the tires won't stay balanced, or has a vibration that is hard to find, I double check the tires, just to be sure. Also, watch the tires from the side too, to make sure they are also still round. Spinning them with an object placed close by for visual reference, helps bring out any possible out of round condition. If they are out of round or true, they can be balanced perfectly, and still vibrate, big time.
Reply With Quote
  #13  
Old 09-13-2001, 07:29 PM
Doug Wilson Doug Wilson is offline
Inactive User
 
Join Date: Aug 2001
Location: Sheridan, Oregon
Age: 79
Posts: 2,510
Default axle?

Long ago, in my checkered past, I ran a Goodyear company store in LA. I never used any weights on my personal balancing, I'd just move the tire around on the rim until it was right. Took a long time, but it almost always worked. When it didn'tt, I'd just put a different tire on. Broken belt could be it. The dot is the light spot on the tire & should be at the stem.
Reply With Quote
  #14  
Old 09-15-2001, 09:44 AM
road chicken's Avatar
road chicken road chicken is offline
Inactive User
 
Join Date: Feb 2000
Location: WI
Age: 58
Posts: 818
Default

The tires have @ 8K on them and never been beaten too hard. They have been doing this from day one. With the way it comes about only after it warms up, I have to think it is the tires. I will check out all the good suggestions here and let you guys know what I found. Thanks
Reply With Quote
  #15  
Old 09-15-2001, 12:09 PM
Tim_K Tim_K is offline
Registered User
 
Join Date: Oct 1999
Location: Southwest Pennsylvania
Posts: 899
Default

I read in one of the Mopar magazines, I think it was in Mopar Action, a while back, an article on tires. It said that the dot on the tire is where the belts were spliced together to make the tire, and if the rim is made properly, the valve stem hole is put at the "low" point of runout in the rim's rotation. The belt splice area will be stiffer, so when it is put at the low point of rim rotation, it should balance out nicely.


I recently had a VERY unusual tire wear situation on my daily driver '71 Valiant. One of the REAR tires wore out along its inner edge, like a front tire with excessive negative camber. I replaced the tire, then a couple thousand miles later, the other REAR tire also wore out along the inner edge. This has never happened to me before, and for it to happen on the rear axle ?!?!?! There were no balance problems with the tires before they wore out. They were a pair of "good used" tires I got from a local junkyard guy who saves them for me. I've been getting tires like that for years with no problem and minimal cost. Short of the entire axle assembly (8-3/4) itself being bent or sagging, I have no idea how this could happen. The axle ran fine with no unusual noises.


road chicken - congratulations on "catching a few" this summer. I need to do more of that myself!
Reply With Quote
  #16  
Old 09-15-2001, 10:40 PM
Billydelrio Billydelrio is offline
Inactive User
 
Join Date: Sep 2000
Location: Del Rio, Texas, USA
Posts: 919
Post

Sounds like the tires may be full of "puncture seal" or something.

Billy
Reply With Quote
  #17  
Old 09-17-2001, 08:36 AM
road chicken's Avatar
road chicken road chicken is offline
Inactive User
 
Join Date: Feb 2000
Location: WI
Age: 58
Posts: 818
Default

TIM-K Chasing is half the fun!
Anyway....... the tires have nothing in them other than air. Considering that the there is no vibration until the tires warm up.I have to start there. The other odd entitiy here is.. it is harmonic.( vib- smooth-vib-smooth-ect). and it's frequency increases with rpm. That is the part thats got me confused. A regular vibration is one thing but this is a new one. Doesn't firestone make Dunlop??? OH GOODYEAR MAN!!!!
Reply With Quote
  #18  
Old 09-17-2001, 04:00 PM
Doug Wilson Doug Wilson is offline
Inactive User
 
Join Date: Aug 2001
Location: Sheridan, Oregon
Age: 79
Posts: 2,510
Default axle

Have you done the runout checks yet on the tires and wheels?? I believe that's where to start.
Reply With Quote
  #19  
Old 09-17-2001, 06:28 PM
road chicken's Avatar
road chicken road chicken is offline
Inactive User
 
Join Date: Feb 2000
Location: WI
Age: 58
Posts: 818
Thumbs up

Nope not yet. I will take this step by step until I find exactly what it is. Starting with your suggestions. It will be a while before I get back to it as the winter button up is in progress. Thanks-
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
axle shaft end play mopartec Vintage MOPAR chat 2 02-16-2010 07:38 PM
axle shaft end play mopartec Restoring your MoPar (Tricks & techniques) 1 02-16-2010 06:44 PM
Axle shaft nut size atvr Ram Truck Chat 2 05-24-2005 11:04 AM
Axle shaft length johndarling Performance Talk 10 03-22-2003 12:49 AM
Axle shaft nut size--HELP! jk_allen Ram Truck Chat 2 08-17-2001 10:35 AM




All times are GMT -4. The time now is 03:32 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
. . . . .