I never had a vibration from the wheel bearings but do know that if they are making noise the noise will go away under braking. So maybe you have a wheel bearing vibration and that's why it gets better under braking? Just a thought.
you checked the wheel balance? thats usually the problem. also check to see if the weighs have fallen off (although mine have before with little effect)
be sure to mark the wheel and tire after the mounting and balance. if they havent dried completely after the mount, they can rotate on the rim under braking (or accel).
Me too! I've had a front end shimmy also. I've had the front end aligned, wheels balanced twice. Never seems to improve. Very smooth up to about 50 or 55, but above that it's pretty anoying. Seems like it may be more common then any of us thought.
[ July 06, 2002, 05:12 PM: Message edited by: Barry N ]
As odd as it sounds, I had this issue on my daily driver. After 2 balances and 1 alignment I still had speed shakes between 45 and 60. The rims where balanced on the outside before and I hate that.
I had them balance with the stick on weights in the inside of the rim both times and still the shake was there. On a suggestion from a co-worker I had them rebalance with the weights on the outside. No more shake. I can't imagine why it makes a difference, I have other cars that the rims are balanced on the inside. Why it made a difference in this case I don't know. Go Figure.
What kind of tire wear do you have? are the inside blocks wearing high/low? Speed shakes are a result of something out of balance. bad tire, rim, bearings loose, or balance. It seems you have eliminated a few of these already.
Did this just start? If so it may be tire related.
What parts of the equation were changed prior to this starting? A trip to the track perhaps?
I don't think control arms bushings would cause such a repeatable (only at 50mph) shake condition.
BTW, the site looks great. keep up the good work..
Bill,
If you can, put a different pair of wheels/tires on the front, even if you have to barrow a pair from a buddy. If the problem is gone you know it's your wheels/tires. Every now and then you'll get a tire that just isn't round. No amount of balancing will solve the problem.
IF YOU are using the rubber bushings in the front rack.. did you put the pipe spacer inside the rubber bushing...if you are using the aluminum offset bushing this can't be the problem...
There are 2 settings on most tire shop balance machines:
1. Static- This balances the up and down force of the tire and one weight is used (inside or outside or stick on in center) This is the setting most shops would use to balance if you do not want weights on the outside.
2. Dynamic or normal (default on most machines) This is both the up and down force (radial) and side to side force (dynamic) This is balanced by weights on the outside and inside offsetting the radial and dynamic unbalance of the tire/wheel combo. This is the best type of balance short of balancing on the car. You can do this without putting weights on the outside, but will require some trial and error and effort by the technician. Put stick on weights inside the wheel as far to the outside as you can get for the outside weight. This will be slightly more weight than the readout shows because the position is inside and at a smaller diameter than the machine expects. After the outside reading is zeroed, put weight on the inside as normal to zero the balance there. I spent many years doing this, so I know it works with wheels with a deep inside like the Mustang and Cobra wheels.
Find a good tire shop and make friends there.
Of course no amount of balancing will cure a vibration from an out of round tire.
Thanks everyone. I'll keep trying. I have tried another set of wheels. I have Cobra-R's with Kuhmos and it still does it. This is nothing new, it's always been here. All new parts! Aluminum bushing in the steering rack.
I had the same problem with 2 sets of wheels and tires, which made me think it was something else for a long time. It turned out that the front wheels were out of balance on one set and the back wheels were out of balance on the other set, but the wobble felt the same.
I had a similar problem like this on my BMW 540 with 18" wheels and aftermarket suspension and brakes. Did all the things you have; turns out my wheels were very slightly out of round. I needed to get the tires shaved every 4-5K miles.
I had them checked for lateral runout, but that was OK. Turns out the bolt centers were very slightly off. After slight shaving, everything would be OK for 2-3K miles then it came back. Three tire shops never found it, a race shop I work with finally checked and figured it out. The error is less than 0.1" but multiplies with tire wear.
Same problem here. I've found the Radial T/A's to have a bunch of runout. So much that you can plainly see it with the naked eye if you jack the car up and spin the tire.
I've had the wheels balanced three times now and front end aligned twice. Checked the studs and lugs for proper seating. The front end feels good and tight but I still get the 55 mph vibration. I'm taking it to a specialty shop that races vintage mustangs to nail it down.
Same problem here.I'm beginning to think that what we are seeing is the road surface being transmitted through the steering gear to the steering wheel.With the manual rack,solid bushings,and solid u-joints all of the vibration dampening is gone from the system and has no where to go but into the wheel.You can feel the vibrations in your regular power steering car,but they are damped out by the time they get to the wheel and feel very faint.To make it worse throw in 17" wheels and a car that weighs nothing.I really hope I'm wrong because it means we'll have to figure out some kind of dampener set up.What we need is a glass smooth road to prove or disprove this idea,but here in the pothole capital of the state if not world I have yet to find said road.Let's keep fighting this thing,there's an answer out there somewhere.Pete.
From my service manual:
Shimmy,Shake or Vibration:
1.Out of balance tire or wheel.
2.Excessive wheel stud runout.
3.Excessive brake drum or rotor imbalance.
4.Worn tie rod ends.
5.Wheel trim imbalance.
6.Worn lower ball joints.
7.Excessive wheel runout.
8.Excessive loaded radial runout of tire and wheel assembly.
Does anyone else have any other causes to add to the list?
I'm surprised at how common this is. Seems like we're all trying the same thing too, multiple attempts at balancing and alignment with little or no improvement.
Is the common thread here the BF Goodrich Radial T/A tires? Is everyone that's having this problem using the Radial T/A's? Should we be pushing BF Goodrich for a resolution?
Who else makes tires in the sizes we need for 15"?
Status
Not open for further replies.
You have insufficient privileges to reply here.
Related Threads
?
?
?
?
?
Factory Five Racing Forum
3.3M posts
50.6K members
Since 2002
A forum community dedicated to Factory Five owners and enthusiasts. Come join the discussion about performance, racing, conversions, modifications, troubleshooting and drivetrain. We discuss MK4, GTM, 818, Type 65 coupe, roadsters, and more!