Front end vibration?

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Front end vibration?

Postby JBurer » Wed Oct 14, 2015 2:36 pm

I put the 550 up for a couple months during the hot summer here. When I took her out, I noticed a shaking coming from the front of the car that you'd notice around 55 to 60 mph - not noticeable below 50 or above 75mph. No real vibration in the steering wheel and I tried that speed range above in different gears to make sure there was no RPM link. There's one other thing that's odd about the problem - the front will shake/vibrate for about a half second and then be completely calm the next half second; it's very regular. You also notice it whether the car is driving straight or around sweeping turns.

Figuring it was tire balance with the narrow speed range involved, I brought the car in and had them done. No improvement.

Then today I had the tires replaced (since they were a little over 10 years old) and balanced. No improvement.

Do you have any ideas to check while I'm trying to find this problem?
Shocks look good... only thing I can think of in the front end of the car that might be an issue is the kingpin bushing - any other ideas?
Best,
John
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Re: Front end vibration?

Postby GT550 » Thu Oct 15, 2015 5:23 am

Since you addressed the tires it can only be a wheel bearing or something worn/broken in the steering/suspension. Maybe you lost grease or it hardened during the down time, a weld broke or a bushing cracked. I would jack up the front end, spin the tires, grab the top and bottom of each tire and check your end play, then move them side to side against the steering/suspension. Hopefully it is easy to find but those kind of gremlins can be tough.
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Re: Front end vibration?

Postby RVosari » Thu Oct 15, 2015 7:36 am

The VW torsion bar suspension system is crude compared to modern designs particularly as it relates to NVH...you may be affected by the natural resonance point of the system, the so called "wheel hop" frequency.

You should also check your steering damper if the car has one.

The Beck Spyders that I have driven are very sensitive to the road surface...for instance driving on new asphalt vs. old asphalt can have a profound difference in terms of overall vibration and steering feedback !

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Re: Front end vibration?

Postby beck688 » Thu Oct 15, 2015 9:29 am

Mine does that when it sits for a bit and the tires get flat spotted -- particularly in the cold. It comes and goes. The suspension is in good shape and the tires are in good condition. There is only about 350 lbs on each wheel - I am running the fronts at about 15 lbs. It comes and goes really depends on road surface -- checking the damper is a good idea, the only way to check it that I know is to undo one end and feel if there is resistance in both directions. For what its worth I have over 20,000 miles on the front tires and they look brand new with hardly any perceptible wear -- I am going to replace them simply because they are 15 years old.
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Re: Front end vibration?

Postby RVosari » Thu Oct 15, 2015 12:37 pm

Beck,

What brand of tire are you using...with the Dunlop Sport R2's I have...you need at least 22 lbs in the fronts, or they peel right off the rim in tight turns

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Re: Front end vibration?

Postby danstern » Thu Oct 15, 2015 1:09 pm

John, follow GT550's trouble shooting guide. He has covered the usual causes, including wheel bearings and linkage wear.
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Re: Front end vibration?

Postby beck688 » Thu Oct 15, 2015 1:43 pm

I am using old school Michelin x - I chalked the side once at that pressure and got very little roll I run about 20 in the rear -- the wear I get on the rears is even across the entire tread. If I go higher the car is skittish
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Re: Front end vibration?

Postby JBurer » Thu Oct 15, 2015 4:56 pm

Thanks everyone! If wheel bearings, would I typically hear a grinding noise or a rough ride?

I'll definitely start on the list and narrow it down

GT350 - just saw you were in Houston. Last minute notice, but the annual Hill Country drive for the local Alfa Romeo guys is this Sat. Other interesting makes are welcome - I'm going in Ruby (my 550). Live in Austin - the drive starts in western Austin. Email me at jburer@yahoo.Com and I'll send more info if interested
Best,
John
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Re: Front end vibration?

Postby JBurer » Thu Oct 15, 2015 4:59 pm

beck688 wrote:I am using old school Michelin x - I chalked the side once at that pressure and got very little roll I run about 20 in the rear -- the wear I get on the rears is even across the entire tread. If I go higher the car is skittish


I echo Rays experience - I had best results on the old tires at 17 front / 23 rear. With these new ones, I'm going to start back at Chuck Becks recc 20 front / 24 rear and work from there.
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Re: Front end vibration?

Postby Biker2 » Thu Oct 15, 2015 9:12 pm

I had the same problem with my car, shake at a certain MPH. Adjusted the toe-in and could move the shake up and down the MPH range. Recently I sent my car back to Special Editions and they quickly recognized my front rims had the wrong offset. Solution was new front rims with correct offset and shake was eliminated.
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Re: Front end vibration?

Postby SpeedwaySpyder » Sun Oct 18, 2015 7:48 am

Mine had a bad steering damper. Fixed mine.
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Re: Front end vibration?

Postby JBurer » Sun Oct 18, 2015 3:55 pm

SpeedwaySpyder wrote:Mine had a bad steering damper. Fixed mine.


Hi Dave! Long time since we spoke last - hope you are well!
How did you test the steering damper on the other car? I disconnected mine and pumped it several times. Seemed to have decent resistance both ways, no fluid leaks and no gurgling noises.

To all - I jacked the car up to check for wheel play grabbing 12 o'clock / 6 o'clock (bearings?) and 9 o'clock / 3 o'clock (tie rods?). Noticed a very, very small amount of movement... is any movement acceptable?

I also noticed the driver's side ball joint boot was torn and a little mangled (picture attached). When I pried on it with a bar, it did have some movement... about 1/8". The passenger side boot looked fine, but it also had some play in it.

Appreciate any feedback on what I said above!
Best,
John
PS Thanks for the suggestion on the rims, Biker2 - since the car has had the same rims before / after the problem, I'm doubtful that's my problem - but thanks for the suggestion!
Last edited by JBurer on Sun Oct 18, 2015 3:58 pm, edited 1 time in total.
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Re: Front end vibration?

Postby JBurer » Sun Oct 18, 2015 3:56 pm

By the way - I noticed the torsion bars each had 2 zerks fittings. How often do you lubricate yours??
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Re: Front end vibration?

Postby JBurer » Sun Oct 18, 2015 5:17 pm

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Re: Front end vibration?

Postby RVosari » Wed Oct 21, 2015 5:31 am

I am using old school Michelin x -
------------------------------------------------------------------

Likely a long term reliable tire. I had to call some Detroit friends to finally gain entry into Dunlop's US Engineering Staff (they blow you off immediately and do not answer questions).

At any rate a Dunlop engineeer finally told me that the problems of unusual wear characteristics on the R2 (used on many Beck Spyders as the original tire) is due to the volatiles and plasticizers exiting the carcass over time.

What this means is that the original durability/hardness ratings mean nothing and wear becomes unpredictable and not dependent on suspension settings !

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