Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 12, 2025 ...

Anyone had bad shimmy when braking hard.

January 15, 2020, 10:22:42 pm

1998 u270, 36 foot

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Re: Anyone had bad shimmy when braking hard.

Reply #1 – January 15, 2020, 11:53:51 pm

I would first suspect the brakes are past due and bad rotors, second slide pins not functioning properly on one side or both.

Just where I'd start, but I am a card carrying member of the know nothing tribe, but I'm learning! 

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Re: Anyone had bad shimmy when braking hard.

Reply #2 – January 15, 2020, 11:53:52 pm

Sounds like brakes sticking. You should get the brakes checked.

Roland

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Re: Anyone had bad shimmy when braking hard.

Reply #3 – January 16, 2020, 12:33:20 am

Warped rotors.

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Reply #4 – January 16, 2020, 12:43:27 am

Pull wheels and check rotor thickness and runout. Check pad condition and evidence of sticking. Pad on one side of the disk may be worn a lot more than other side. Heat can warp rotors. Easy to check yourself. Wear in suspension parts can amplify the pulsation/shimmy. HF has inexpensive tools to measure thickness, magnetic base and dial indicator for runout. Meritor maintenance  manual can be found on this site under Media then Foretravel Library.

Pierce

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Re: Anyone had bad shimmy when braking hard.

Reply #5 – January 16, 2020, 05:56:07 am

I did. I had the front end looked at in Colton, Ca and all they found was 1 slack adjuster  out of adjustment. Since it was adjusted I have not had the problem again. That was about 6 years ago. Now I know how to adjust them myself (thanks Dave Dunnigan). Forget about "self adjusting slack adjusters".

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Re: Anyone had bad shimmy when braking hard.

Reply #6 – January 16, 2020, 06:59:55 am

When I first got my coach, it happened to me 2 times. The second time had me on the side of the interstate. Checked out for overheat, try to see if anything looked odd. Nothing. It has never happened again in 5,000 miles. I assume that the brakes had built up a slight amount of rust and had stuck. Since then, I make sure to use the brakes in addition to using the retarder just  to keep them loose.

Larry

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Re: Anyone had bad shimmy when braking hard.

Reply #7 – January 16, 2020, 08:57:33 am

OK, coach is  22 years old.

When was the last full brake service (check slide pins, check pads, check rotors for heat cracking, bluing, out of true, and lube calipers)?  Helper springs installed?

Rather than try to diagnose the symptom and just fix that (likely bad rotor, likely caused by lazy side of caliper not retracting from disk) may be time for a complete brake inspection/service.

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Re: Anyone had bad shimmy when braking hard.

Reply #8 – January 16, 2020, 12:00:46 pm

It can be SUPER alarming when the coach violently shakes back and forth when you break hard.  But no worries...the above responses = nail on head.  Warped rotor, possibly only the slide pin.  We had the same issue, and had it addressed last May at MOT.  Fixed the slide pin first, still happened on test drive, replaced rotor, perfect drive ever since.   

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Re: Anyone had bad shimmy when braking hard.

Reply #9 – January 16, 2020, 01:46:14 pm

Yes and it was the combination of out of round tires and worn shocks.

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Reply #10 – January 17, 2020, 07:48:53 am

Olde English, I didn't put the points together till now, but when I had my shimmy, the tires I had on were out of round also. New Toyo's and Centramatics, smooth sailing ever since.

Larry

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