Thumping noise rear wheels

F

flybobbie

Elite
 Stourbridge
Well week or so now hearing the rear wheels thumping and bouncing as though a shock absorber is duff. At first tried lowering the tyre pressure as i'm running non RFT and 42 psi seems a bit high.
But this morning probably due cold tyres the thumping seems quite noticeable.
 
flybobbie said:
Well week or so now hearing the rear wheels thumping and bouncing as though a shock absorber is duff. At first tried lowering the tyre pressure as i'm running non RFT and 42 psi seems a bit high.
But this morning probably due cold tyres the thumping seems quite noticeable.
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I would run the non runflats pressures the same as runflats i.e. 36psi fronts and 37psi rears if on 18s. 42 I would say is a little high at cold temps. I run 32psi all round on the Z3 on 18s.

Tim.
 
Will try running at 38 all round as that is what i run on the front. Its as though every undulation the wheel wants to skip over with a bump noise.
Might be just combination of tyre pressure, low atmospheric pressure and cold temperature.

Love the car, but just getting a bit cheesed off with niggly problems.
 
Is this thumping sound random or cyclic? If its random it could be high pressures or a duff shocker. If its cyclic then that might suggest a faulty tyre so check them for bulges on the inside and outer faces or indeed even the tread.
 
Maniac said:
Is this thumping sound random or cyclic? If its random it could be high pressures or a duff shocker. If its cyclic then that might suggest a faulty tyre so check them for bulges on the inside and outer faces or indeed even the tread.
Click to expand...
+1. Could you have a puncture where the tyre hasn't deflated that much? I once had a puncture where the piece of metal (mostly long and thin) was embedded so much it was hard to spot in the tread / not clearly visible. It gave a cyclic thumping / clicking noise (as Maniac suggests).
 
Only happens on undulating road surface such has country lane where the surface looks like a sine wave. i drive down such a road everyday, so experience the bumping on every drive. Also the odd patch of lifted road surface. No sound on flat road.Tried lowering the tyre pressure, no difference. First thought is a shot damper. I know we sit over the rear axle area and can feal the bump slightly through the seat.
Sounds a bit like a lump hammer left in the boot bouncing up and down.
Yes i have tried emptying the boot down to removing the boot battery lid.
 
I,l say it a bit louder :oops: BROKEN SPRING :roll:
When i had a rear spring go not long after buying it i also thought there was something loose in the rear well area , , , turned out it was the loose part of the coil rattling around over bumps , could also affect handling if broken badly
 
I've never heard of a broken spring (common to e85 and some e86) on the e89 but that's not to say damage can't occur. But when I had a spring go on my e85 it was a bong noise not a thump when going over undulations. A thump could be all sorts, shocks, top mounts, bushes etc...
 
Replaced with Bilstein b6 and all quiet now.
Can't see whats wrong with the originals at 44k miles, no leaks just seem slow on rebound compared to the replacement.
First inch of compression has slack, before any resistance, and some gurggling of the fluid inside.
The BMW originals take 35lb force to compress and extend in 10sec and the Bilstein 50lb force and extend in about 6 seconds?
No more bumps or wheel spin on a bit of loose gravel or damp.
 
Bit of an update.

Was still getting a mild bumping noise, that could be felt under drivers seat.
So whilst having the rear wheel off to check bushes i decided to pull spring off and have a good look.
All ok. I washed the top and bottom rubber mounts and refitted spring.

All bumping noise gone?

Having just got access to BMW TIS document it mentions spring problems on another model of BMW. Problem being the barrel spring gripping rubber mount and then rebounds with a bump.

When i bought the car there was a problem with a knocking noise sounding like someone hitting the bottom of the boot with a rubber mallet. Initial cure was grease on anti roll bar bushes, then i replaced bushes with polybushes. But always thought this was a sticking plaster to the real problem.

BMW solution was to talcum powder the top rubber of the springs, which i have yet to try, simply because disturbing the spring and washing the rubbers seems to have cured the problem.


Update 29/04. I checked the spring and i noticed that i have rotated the spring when installed to a different position. The letters S1 was printed on the spring visible on the outside which must now be near the back of spring as viewed as i can't see it. Seems to have cured the clunks and bumps.
Might invest in two new upper rubbers, they are shaped like traditional Amish mens hat and have noticed the one washed, the 'rim' is floppy when under spring load as it bares only around the centre and could be flapping against the bodywork when the spring goes up and down. Might be idea to glue the rubber to bodywork.
 
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