steering shimmy on highway

darylrobert · Post by **darylrobert** » 08 Mar 2021, 03:40

Just did a 4 hour 500km round trip in my 2001 xc70 has a very slight steering shimmy on at 100km/h speed, go alittle faster on slower and it goes away, thats wheel balance or could it be something else like the drive shaft is out of balance?.had the front alignment and balance done mid last year but due to covid this is my first highway trip. car was driven weekly around town during covid so dont think its flat spots.

ignatz · Post by **ignatz** » 08 Mar 2021, 06:16

If one front wheel feels warmer than another, after a drive, it could be a brake caliper hanging up. I have extra wheels and tires to swap around to see if the shimmy goes away.

Post by **oragex** » 08 Mar 2021, 07:18

Is it always there at 100kmh?How fresh are the control arms ? I am thinking possibly play in one CV joint

Post by **xHeart** » 08 Mar 2021, 11:47

darylrobert wrote: 08 Mar 2021, 03:40 Just did a 4 hour 500km round trip in my 2001 xc70 has a very slight steering shimmy on at 100km/h speed, go alittle faster on slower and it goes away, thats wheel balance or could it be something else like the drive shaft is out of balance?.had the front alignment and balance done mid last year but due to covid this is my first highway trip. car was driven weekly around town during covid so dont think its flat spots.

First impression is a give in the bushings somewhere. I would drive and wait for it to occur often, and over a wider speed band.
FWIW, check items 1, 3 & 4 with all wheels are on the ground -- re-torque safely.

darylrobert · Post by **darylrobert** » 09 Mar 2021, 01:02

thanks for the suggestions, i will try rotating the tyres and give them a good clean. I have found a shop that does "road force" balancing which i read is a better way of balancing tyres. My disk rotors are fairly grooved and probably too worn to machine, i wonder if they could cause an imbalance.

OI have 18inch "R" rims with the recommended size "made in China" Pirreliis

Post by **RickHaleParker** » 09 Mar 2021, 01:23

Inspect the tires for shifted or broken belts.

Post by **MoVolvos** » 10 Mar 2021, 19:42

darylrobert wrote: 08 Mar 2021, 03:40 Just did a 4 hour 500km round trip in my 2001 xc70 has a very slight steering shimmy on at 100km/h speed, go alittle faster on slower and it goes away, thats wheel balance or could it be something else like the drive shaft is out of balance?.had the front alignment and balance done mid last year but due to covid this is my first highway trip. car was driven weekly around town during covid so dont think its flat spots.

If the brakes do not pulse when depressed then check the tires first by rotation if you don't want to pay for a balance. Bumping to 4PSI below max pressure will also give you an idea whether it's tire related. What is the DOT Date and brand?

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Post by **SuperHerman** » 10 Mar 2021, 22:42

Control arms are my first suspect.

darylrobert · Post by **darylrobert** » 11 Mar 2021, 06:11

thanks, i cleaned and rotated them today. because of the hot climate i inflate tyres to 40PSI, i will try 35PSI. Tyres are Pirrelli dragon, ive been reading other forums about the "Pegasus" being horrible for balancing. Three of my 18inch pegs have the weights around the valve stem area, one wheel has over 100grams of weights.

Pic below isnt my wheel, the weights on my pegs look bigger and uglier than this and can be seen from the other side.

do i have a buckled rim?

: pegasus balance; pegasus.jpg (137.5 KiB) Viewed 902 times

Post by **MoVolvos** » 11 Mar 2021, 23:05

darylrobert wrote: 11 Mar 2021, 06:11 thanks, i cleaned and rotated them today. because of the hot climate i inflate tyres to 40PSI, i will try 35PSI. Tyres are Pirrelli dragon, ive been reading other forums about the "Pegasus" being horrible for balancing. Three of my 18inch pegs have the weights around the valve stem area, one wheel has over 100grams of weights.

Pic below isnt my wheel, the weights on my pegs look bigger and uglier than this and can be seen from the other side.

do i have a buckled rim?

pegasus.jpg

Did the vibration in the steering go away after the rotation? Since you have the weights in stem area on all four wheels, let's hypothetically say Volvo received a batch of rims with the mold producing heavier wheels near the stem. As long as it is not warped you can try the Force Balancing as it should reduce if not remove all the weight issues of the tires.

When I worked at Pepboys in the mid 90's when a tire or rim combo had excessive weighs on one side, we just un-beaded the tire and rotated it 180 degrees and re-balance. Unless the tire and or rim was out of round that usually took care of balancing issues.

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