Tire conundrums

carl

True Classic
In a past post I mentioned how the Achilles were just perfectly round and balanced on the Bertone. I put the exact same wheels and tires from the Bertone on the 77X and now I have what feels like a few ranges of unbalanced tires...steering wheel shakes at certain speeds and even the shifter shakes noticeably fore and aft at some speeds. What the hell would cause that...perfect on one care and shakers on the other?

Side notes, I changed out all four new struts for the ones that came on the car and it made no difference...also swapped tires front to rear and no difference.

Next I'll put on the iron crosses and 10 year old Sumitomos that came on the 77 and see what happens.
 
I stand in agreement with the above statement by the honorable Mr Hynes.
 
steering wheel shakes at certain speeds and even the shifter shakes noticeably fore and aft at some speeds
I would check the "fitment accuracy" of these wheel/tyres, now on your 77X. I would find it hard to believe that wheel/tyre assemblies that were OK on your Bertone suddenly became "sort-of un-balanced" on your 77X!
Have a real good bo-peep to make sure that you haven't got one (or more) of the newly-mounted wheels (now on the 77X) slightly askew on the hub/s.

cheers, IanL - NZ
 
I would check the "fitment accuracy" of these wheel/tyres, now on your 77X. I would find it hard to believe that wheel/tyre assemblies that were OK on your Bertone suddenly became "sort-of un-balanced" on your 77X!
Have a real good bo-peep to make sure that you haven't got one (or more) of the newly-mounted wheels (now on the 77X) slightly askew on the hub/s.

cheers, IanL - NZ
Get the tires off the ground and spin each one by hand and check the run out on inner and outer rim.
Like Ian said you might have a bad fit on one or more hubs.
 
Bad alignment, worn suspension parts such as tie rods, bad steering rack bushing, witches hex, etc...
Rims with corroded center bore that lets the sit differently every time you mount them
Corroded hub or brake rotor
Bent hub
 
OK guys, good thoughts. I'll investigate. The wheels do use shouldered bolts but I have used these wheels on many Fiats with no problem.
 
One thing I've learned after experiencing hard to balance Yokohama tires was to use a really good balancer - I found a local shop that has one of these Hofmann Optima laser balancers - WOW! The thing even divided up the weights and placed them in behind the spokes of my CD91s! Oh, and it even locates on the bolt holes (doesn't touch the wheel face) 4x98! woo hoo!

I had some serious vibration issues as the tires were not quite round... but this machine made it perfect. I feel zero vibration :)


(this isn't related to Carl's issue - just wanted to chime in!)

 
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The problem is the tires were dead smooth on the Bertone, all I did was take them off and install on the 77. I put the 10 year old wheels/tires back on the 77 and they hop around too at certain speeds. This seems to be one of those dreaded Xs that too sensitive to tire balance. No play in the steering, wheels are true...and of course these tires could be flat spotted since the car really hasn't been driven in about 10 years but has been moved from one place to another.
 
Hmm, this really sounds like it is something other than the wheels... Have you ever had a set of wheels on that car that didn't vibrate?
 
Any chance a rotor is loose or not quite seated against the hub? Is the hub face rusty? A bad CV joint? How are the boots?
 
Ed, I have only had two sets of wheels on the car and they both showed the same symptoms. Next step is the iron crosses/Federals that are OK on the Bertone but I'm getting tired of swapping out tires, I'm no NASCAR pit crewman.
 
You might discover the problem by running the car in gear with the rear wheels on jack stands. Note: this is dangerous, be careful.
 
True but it's the steering wheel that's shaking which would indicated the front wheels are the problem.
I'd love to put the wheels on a balance machine but I can't see paying for a four wheel balance on 10 year old tires which I'm not thrilled to be driving on.
 
Ed, I have only had two sets of wheels on the car and they both showed the same symptoms. Next step is the iron crosses/Federals that are OK on the Bertone but I'm getting tired of swapping out tires, I'm no NASCAR pit crewman.


Hmm, two sets of wheels on the same car that show the exact same symptoms makes me think it isn't the wheels... I get back to town on Monday and am around all week if you want a second set of eyes...
 
Exactly! What I didn't do was record at what speeds the steering wheel shakes. Would be interesting if different wheel/tires all had problems at the same speed. I tested all four wheels for runout and they all ran true and the iron crosses are hub centric. The other wheels use shouldered bolts and are not hub centric but I have had them on three different Fiats with no shaking issues.
 
Just got back from a drive. Steering wheel starts shaking at around 50 and stays shaking from 50-60 (I couldn't go faster on this road) and noticed the shaking cycles. Pull away from a light and get up to that speed range and the steering wheel starts shaking but if I maintain that speed the shaking smooths out to nothing.
 
Glad I found this. I have been getting to this same situation this summer, bad enough to where I barely made it home Friday. Well, had to slow down to 40 or so. Thought I lost a lug or the wheel was coming loose, but could not see anything when I pulled over, so then I crawled it home.
I also can't tell if it is the front or rear. Originally when it was minor I thought maybe I lost a balance weight on the right rear. But it would also make the steering wheel shake some at 50-65 and get bet above that.
I have had to take off the rear wheels and the front right for other issues and also thought maybe they were not centered although I have an 86 with the wheel bolts that have centering shoulders that match the stock wheels.
So I hope someone can help Carl and/or myself.
Thanks, Stu
 
If the steering wheel shakes it's the front wheels. If you feel the body shake or the shift lever is shaking it's probably the rear wheels. Maybe you can go for a drive and have a friend drive around you looking at the wheels to see if they can detect your wheels doing anything strange. My wheels were mounted with long wheel studs and I removed them and reinstalled the iron cross wheels with the proper wheel bolts. This seemed to diminish things a bit but I need to take the car on a longer drive to be sure. I will say I'm getting really tired of removing and installing wheels all the time.

Next step is to reinstall the newish KYB struts, I removed the sport springs and installed stock springs. While doing this I noted these newish struts are actually gas struts and that probably explains why the car sat high even with sport springs. So I assume the car will sit even higher with the stock springs which means I will then have to remove the KYBs yet again and cut the stock springs...and did I mention you have to always take the wheels off to do this!
 
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