Some braking advice needed....please

[normspanners]

I only went to Demon Twits cos they were the only people I could get the clamps same day

Ok no probs, anything you need just ask I'm surprised at that re tweeks, actually,------ your local MAC or snapon man would have had em, but hey ho.

I may end up selling the car anyway as swmbo thinks it makes her feel ill - can't imagine why 0-70 mph in 7 seconds would make anyone ill

Daft as it might seem she might be feeling the bad brakes more than you think, I was passenger in my lads bmw and could feel the tracking was out and he hadnt noticed ! I could feel the car was 'nervous'.

 

[Gareth J]

Hopefully the new rear bits and bobs sort it. I'm not convinced by the brakes on my 3 series, always seems like there is something sticking and the handbrake is terrible.

Regarding crusty discs, there are probably many many reasons but I put mine down to the vehicle being parked up for a while and rust being allowed to set in. As rust is pretty hard, if it gets the chance to scour a section of the pad away before the pad can bust it off, the pad is then worn unevenly and the now heavy and polished rust will just keep wearing the pad down.

There were 5-10mm rust rims around the discs on the above 3series. Not critical but when new pads were fitted, I bashed the hard rust off to give the new pads a half a chance to keep discs clean. I doubt it worked but worth a try!

 

[Wendelspanswick]

Hopefully the new rear bits and bobs sort it. I'm not convinced by the brakes on my 3 series, always seems like there is something sticking and the handbrake is terrible.

Regarding crusty discs, there are probably many many reasons but I put mine down to the vehicle being parked up for a while and rust being allowed to set in. As rust is pretty hard, if it gets the chance to scour a section of the pad away before the pad can bust it off, the pad is then worn unevenly and the now heavy and polished rust will just keep wearing the pad down.

There were 5-10mm rust rims around the discs on the above 3series. Not critical but when new pads were fitted, I bashed the hard rust off to give the new pads a half a chance to keep discs clean. I doubt it worked but worth a try!

I get the bit about the rust scouring the pads down but not why it seems to affect the inside of the discs more.

 

[normspanners]

read post 19

 

[Gareth J]

read post 19

Looks like I should have read post #19 too!

Glad to know I'm not just talking rubbish

 

[normspanners]

I cannot understand manufacturers of commercial vehicles fitting just pressure limiting valves to the rear when load sensing valves should be fitted to all commercials IMO.
I understand the problem of the unregulated pressure on the brakes locking the wheels in the wet when running light and that can cause problems with vehicles skidding at the the rear, with their unladen weight of say 700Kg but when they are loaded to 2000kgs they then may need maybe twice the braking at the rear, when an emergency arises, but they still have limited pressure brakes still at 700Kg the added braking HAS to be done at the front which can induce a front end to lock up causing loss of steering etc or with abs the front axle having reduced braking available because as the wheels lock the brakes are released momentarily,
The good old load sensing valve limits the brakes when running light then it increases the rear braking as the load at the rear increases and then as the weight is transferred from the rear as you brake the rear brakes reduce accordingly to balance it all out.

 

[normspanners]

My mate has a fiat based motorhome and is always complaining that it locks up the fronts when going down his leaf VERY steep drive and CANNOT reverse down coz he looses control, it is all down to the standard pressure limiting valves in the rear line, the thing has 2800 kg axle which is at max ALL the time( sometimes well over actually with the trailer on) but the brakes are set to an empty standard van at 700kg so when he brakes because he is below the abs speed the fronts lock and he looses control I have told him he should pipe out the limiters but he wont listen, saying that the insurance might not pay out when he hits something----- wrong way to think I believe.

 

[gerrymoore]

Quick update...I've changed the discs and pads and cleaned the calipers like new. Couldn't really find anything 'wrong' but the pads were very low and the discs, although not rusty or scored, were within 1mm of the wear limit so a job well done anyway. The caliper pin sliders were very dry and slightly marked but cleaned and silicon greased they should be fine.

I was just too knackered to drive the car afterwards (just getting too old for car DIY ) so today I shall take it out and see what's what...bearing in mind I need to bed the pads in a bit first.

Just like to thank everyone again for their input on this - hopefully we've all learned something...

 

[gerrymoore]

As Paul Newman said...Still shaking boss I've taken the car up and down the motorway but the pedal is still pulsing. I've had my thinking cap on and come up with a couple of points. First, the car was fine and then it started this pulsing..always the pedal not the steering wheel. It's worse when I have passengers...especially with 4 in the car.

Only thing that may explain it is that a few weeks ago I hit a very large pothole - made me cringe at the time and I even got out to check the front wheel. Then, last Sunday, I was out in Wales and hit another pothole..only at about 25 mph but the noise it made was absolutely horrendous - almost like the car had completely bottomed out with no bump stop!

So now, after another sleepless night, I'm thinking it must have damaged the suspension - maybe a bush or worse.

I haven't really got the facilities on my drive to examine the underneath too well so, first, I'm gonna ask Norm if he's able to help.

So Norm...pm sent.

 

[dobbslc]

Can you jack the car up and spin the wheels with a pointer a few mm from the rim? You might have a bent wheel (I think BMW had a real PR problem with rims getting bent easily and not wanting to know about it)
You could also have a knackered side wall on a tyre look out for bulges.
My wife's Zafira had 3 bent rims on it due to potholes!

 

[gerrymoore]

Hi Dobbs..don't think it's the wheels..they're very wide alloys and would probably crack rather than bend..the tyres are runflats so have very strong sidewalls..I reckon it's a suspension problem..Norm is going to take a look next week.

 

[normspanners]

Will have a look certainly.

 

[normspanners]

Yes BM's have big wheel cracking problem even in this country I know we think its bad but just try driving in greece or some eastern ones !! dont know what the wheels must be like in the cheq bosnia bulgaria etc must have to run tubes there !!

 

[octo0072000]

believe what Dobbs said
bigger the rim and lower the profile the rims will buckle range rovers are prone to it big pot hole bent rim
they also do crack seen volvos split the hole rim round just held together by the tyre

 

[gerrymoore]

I'll check the rims but the car is as smooth as you like at 70 plus mph - steering is perfect not a trace of wobble..only time i have a 'problem' is braking - and that's intermittent ....just to make things worse

 

[octo0072000]

that's the main problem intermittent means unless you can show the problem to someone.
sorry sir no fault found
with low profile tyres it's the rim that gets the hammering
because the sidewall is so stiff

 

[normspanners]

Norm is going to take a look next week.

Nice to meet Gerry's BMW yesterday----- very nice car------ cant say the same for him though -------HAH
I jest, very nice guy we spent 5mins looking at the car,------ and the rest of the time talkin BS and slagging the rest of you lot OFF!
HEHE pretty sure its not abs all reading PERFECT !! not seen them as even on most other cars exactly the same down to decimal point on the straight
After checking suspension etc for 5mins it was decided that a cup of coffee might fix it, and it did!!! it didnt shake at all during the coffee.!
Seriously though I'm, pretty sure it is brake reaction bushes causing wheel shake.
Thanks to Gerry for the lift home, I didnt really want to go all the way to his house ------but it was a nice walk back .

 

[roofman]

Nice to meet Gerry's BMW yesterday----- very nice car------ cant say the same for him though -------HAH
I jest, very nice guy we spent 5mins looking at the car,------ and the rest of the time talkin BS and slagging the rest of you lot OFF!
HEHE pretty sure its not abs all reading PERFECT !! not seen them as even on most other cars exactly the same down to decimal point on the straight
After checking suspension etc for 5mins it was decided that a cup of coffee might fix it, and it did!!! it didnt shake at all during the coffee.!
Seriously though I'm, pretty sure it is brake reaction bushes causing wheel shake.
Thanks to Gerry for the lift home, I didnt really want to go all the way to his house ------but it was a nice walk back .

Hey Norm,did he sell you my snap-on inductive timing light and impact kit i lent him...i have,nt seen them since 1931

 

[normspanners]

Hey Norm,did he sell you my snap-on inductive timing light and impact kit i lent him...i have,nt seen them since 1931

He did try, No didnt need them, already have the same kit!

 

[normspanners]

IMO frequency is wrong for ABS and no sound that I could hear.