Brake pulsation - Saxperience

Jonathancilia · 26th April 2018, 19:36

So recently i installed a set of alloys 14 inch on my saxo, they have almost new tyres on them.

On the rear of the car i have a slight very minor wobble at high speeds that i feel in the seat not the steeringwheel. I believe that the rim has a very minor bend. Im not too worried its not very noticeable.

The thing is this, i know that my rear brakes are shit they are all grooved even the drums. Before i installed the new rims i didnt have any pulsation but after i installed the new rims i now feel a pulsation when i brake from say 80km/h in the seat of the car. Could this be caused by the slightly bent rim?

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marrick · 26th April 2018, 19:39

The wobble would just need the wheels balancing on the back mate

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Jonathancilia · 26th April 2018, 19:40

Im not so sure because when i spin the wheel i can see a minor bend in it, its not tracking straight

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Jonathancilia · 26th April 2018, 19:41

But still how can the brake pulsation issue reveal itself now? Before i installed the new rims the drums were already grooved and braking was smooth

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MartinObviously · 26th April 2018, 19:47

The bent rim will be making the drum "shake" very slightly. so you may feel that in the pedal.

Quick test would be to put your other wheels on and go for a drive. If it goes away you know 100% it is the wheels.

Jonathancilia · 26th April 2018, 19:49

Yeah i thought about that possibility, but its fastened by the axle nut and i rotated the brake drum its pretty straight, could it still possibly wobble because of the wheel ?

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marrick · 26th April 2018, 19:49

Quote:

Originally Posted by Jonathancilia

But still how can the brake pulsation issue reveal itself now? Before i installed the new rims the drums were already grooved and braking was smooth

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Tyres wouldn't really make the brake pulsate, I would work in narrowing the fault down.

Swap your wheels front to back and see what happens, if the wobble is felt through the steering wheel rather than the seat then they definitely need balancing.

Then put your old wheels on the front, keep the 14" alloys on the back and see if the wobble goes and your brakes feel okay. If your brakes are still crap pur your original wheels on and again see what your brakes are like.

IF the brakes are terrible with all of your standard wheels back on then you need to rule out warped discs, best way to do It is run it over some brake rollers (and MOT test station has them). You don't really get issues with warped drums tbh.

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Jonathancilia · 26th April 2018, 19:51

Ok then tomorrow i will swap wheels back to front and see what happens

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marrick · 26th April 2018, 19:52

Keep us posted

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Jonathancilia · 26th April 2018, 19:52

I used spacers with the wheels and extended bolts, this doesnt make a difference right?

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marrick · 26th April 2018, 19:56

I've got those on my saxo and there fine, they are decent ones and not home made ones right? They have to be perfectly balanced. Again that wouldn't effect your drums.

Is it definitely the back drums causing the issue? When driving pull your handbrake SLIGHTLY, that will operate the back brakes only... If it judders then it's the back, if not and it's juddering with your foot brake it's the front

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marrick · 26th April 2018, 19:58

Quote:

Originally Posted by marrick

I've got those on my saxo and there fine, they are decent ones and not home made ones right? They have to be perfectly balanced. Again that wouldn't effect your drums.

Is it definitely the back drums causing the issue? When driving pull your handbrake SLIGHTLY, that will operate the back brakes only... If it judders then it's the back, if not and it's juddering with your foot brake it's the front

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That goes without saying, best done on private land with no traffic around etc....

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Jonathancilia · 26th April 2018, 20:00

Yeah when i apply handbrake i feel vibration i tried that and yes they are quality wheel spacers

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marrick · 26th April 2018, 20:08

Quote:

Originally Posted by Jonathancilia

Yeah when i apply handbrake i feel vibration i tried that and yes they are quality wheel spacers

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Definitely try putting the original wheels on the back and see what happens. It's not something simple like the drum not seated correctly? I'm assuming the drums still had the little grub screw that holds it in place when the wheel is off?

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Jonathancilia · 26th April 2018, 20:23

So i went outside and replaced the said bent wheel with the oem wheel and its abit better now, it still pulsates but its less

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marrick · 26th April 2018, 20:33

Hmm strange, what if you change the other rear wheel? Does it stop pulsating?

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Jonathancilia · 26th April 2018, 20:39

I didnt check but both rear wheels have a slight wobble when turned

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Jonathancilia · 26th April 2018, 20:39

Can this be fixed with wheel balancing ?

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marrick · 26th April 2018, 20:48

You wouldn't be able to see them being out of balance to be honest, but I would get them balanced definitely. The allot wheels do have the correct size centre bore right? And definitely sit flat against the drums?

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Jonathancilia · 26th April 2018, 20:50

They sit flat on the spacer and when i jack the car up and release the handbrake and i spin the rear wheels they got a slight wobble, i really cant tell if its the tires that are out of round or the wheels

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