Shake at hiway speeds(50mph and above)
11-12-2010, 03:40 PM
#1
Shake at hiway speeds(50mph and above)
Recently lowered the car and noticed that the it starts to shake at speeds over 50mph. I checked the wheels and they seem to be balanced ok. I did not try to "road force" balance them though.
After putting the springs(H&R) on, I had the car aligned. They were not able to get the passenger side front set all the way so it is slightly out of spec. My seat of the paints guage tells me that the shake does appear to be coming from the passenger side front. When aligning they said they were at the limit with no more adjustment, of course I don't remeber what adjustment they were talking about.
The car does drift slightly to the right, not bad but noticeable.
My question is could a bad alignment cause a vibration at hiway speeds that has the same symptons of a wheel not being balanced properly? Could there be something the tech did not reattach properly?
After putting the springs(H&R) on, I had the car aligned. They were not able to get the passenger side front set all the way so it is slightly out of spec. My seat of the paints guage tells me that the shake does appear to be coming from the passenger side front. When aligning they said they were at the limit with no more adjustment, of course I don't remeber what adjustment they were talking about.
The car does drift slightly to the right, not bad but noticeable.
My question is could a bad alignment cause a vibration at hiway speeds that has the same symptons of a wheel not being balanced properly? Could there be something the tech did not reattach properly?
11-12-2010, 04:47 PM
#2
Race Director
Recently lowered the car and noticed that the it starts to shake at speeds over 50mph. I checked the wheels and they seem to be balanced ok. I did not try to "road force" balance them though.
After putting the springs(H&R) on, I had the car aligned. They were not able to get the passenger side front set all the way so it is slightly out of spec. My seat of the paints guage tells me that the shake does appear to be coming from the passenger side front. When aligning they said they were at the limit with no more adjustment, of course I don't remeber what adjustment they were talking about.
The car does drift slightly to the right, not bad but noticeable.
My question is could a bad alignment cause a vibration at hiway speeds that has the same symptons of a wheel not being balanced properly? Could there be something the tech did not reattach properly?
After putting the springs(H&R) on, I had the car aligned. They were not able to get the passenger side front set all the way so it is slightly out of spec. My seat of the paints guage tells me that the shake does appear to be coming from the passenger side front. When aligning they said they were at the limit with no more adjustment, of course I don't remeber what adjustment they were talking about.
The car does drift slightly to the right, not bad but noticeable.
My question is could a bad alignment cause a vibration at hiway speeds that has the same symptons of a wheel not being balanced properly? Could there be something the tech did not reattach properly?
Be sure the tires are all properly inflated. Check them cold. I've found even a few psi over-inflation can produce a vague sort of tire balance/shimmy symptom.
If you tell me the wheels/tires were ok before the suspension change and a close inspection of each wheel reveals no signs of any missing wheel weights, then re-balance probably not called for.
Then the issue becomes were the wheels installed correctly? The wheels and hub mating surfaces want to be clean and free of any dings, dents, etc. Also, the wheel lug bolts need to be torqued down properly, in sequence, and in several stages.
What are the alignment specs? You really need to get a copy of the before and after alignment settings. Some settings are neutral regarding shake/shimmy but some are not.
Regardless, you may have to go to special suspension hardware (Porsche or aftermarket) to provide enough additional adjustment the alignment can be brought spot on the money.
Then of course the spring installation has to come under some suspicion. An improperly installed component, a missing shim, a component left loose, or one that may have been bent or worn out before may now because of the suspension changes manifest a symptom it did not before with the stock springs.
In short you need to follow a process of elimination eliminating those items that are least expensive to eliminate and yet of course could still play a role, contribute to the symptom.
Sincerely,
Macster.
