Contour Enthusiasts Group Archives Forums General Troubleshooting SHIMMY at 66 mph and up to 70+

i get this bet of harmonic thumping at these speeds
I did recently get a new front tire and rotated a back one to the front , both were balanced .. the rears may need balancing but the whole car may need a 4 wheel alignment too.. all that caster and camber may be out of whack.. anybody get the same kind of thumping noise above 65 mph on there contour ? mines a 95

If one of the tires is slightly "out of round" compared to the other one, then I'd bet money this is your problem. The new tire won't have the same amount or type of wear that your old one does.

a VERY good rule is to stick to 2 replacements if 1 tire goes bad. The difference in wear could wind up causing trouble in a panick brake or in foul weather. Nothing like an unplanned spin or a four wheel lockup drifting into the shoulder!!!!

Likely the old tire is causing the problem. Have you ever noticed how quiet and smooth the ride is when you get new rubber?

the tire was on the back and there isnst much wear on the rears as the drive power is in the front.

they are the same bfgoodrich high speed rated from sams ..
i think it was $59 a peice plus $9.99 which buys you lifetime rotation and rebalancing - not too bad .. (but who rotates every 5000 ? .. yeah i think that rear one that came to the front was maybe 10000 miles old but it was moving from the rear.. i would say maybe a 1/16 and at most 1/8" tread has worn.. they are 60's . 185 or 205 .. something to do with the circumference inner compared to outer or compared to width .. or maybe its the # millimeters of width .. anyway they are the same tire but maybe that 1/16" tread difference is enough at 66mph to cause the problem..

also .. maybe the caster and camber are off sufficiently that until the 1 brand new tire and other 'new' tire that moved from the front to the back gets the feel (wear) of the present alignment conditions it is causing the thumping .. so .. thats my theory ...

I don't think there is any caster adjustment for the contiques...

well i got a couple of piece of metal stuck in my rear tire while driving a guy's route for my job and assisting this guy with his stuff and my stuff to get the job done.
So it was time to replace both rears. BF goodright $62 a peice plus $9 for the balance and all that .. and they are 60R 215 15" .. anyway .. my high speed thump has now shifted to low speed . smooth at high speed but about 25-35 or so __ON DECELERATION __ mainly.. i hear this horrible thumping.. i thought it would break in.. well ...we'll see

another thing .. dont take your car to get tires done on the last day of the main workweek (Friday)on a hot day when people are agitated at the end of the last day and unhappy , behind and understaffed.. your job gets done late and in a hurry .. like my power seat was making funny noises like the guy got in there and tried forcing it thinking it was a mechanical movement not electrical screw movement..
I had to make special reminder about the lift points. And retell the story about how BJ's did $1000 damage by lifting improperly. anyway , one of the guys who wasnt there initially remembered me .. but still he didn't do the tire change, just the lift.. and another guy drove the car out ..
You can't lift the car in the front by jacking under the carriage 'runner' pan .. it will get squashed .. it must be lifted at the subframe area. Simple thing, but people not used to it and in a hurry and with distractions can slip and it happens when the blur of many cars in and out, in and out and you just want to get done.. So make sure to point out about the lift points ! You can lift at the special area where designated on the side(using the spare tire jack) for a tire change but that's just mainly for emergency change of one tire.

I put on tires and rims from another Contour and had same problems. They just needed to be balanced for my car.