Elimanating Brake Shudder

[Tom_1569]

The VT brake shudder has become dangerously BAD, i mean it will weave in the lane sometimes cross just trying to brake, its a mission when braking hard. We are clocking over 600k's a week so we need to fix it and ELIMINATE IT. Rotors were machine last time and it didnt last 200km.
Im thinking DBA slotted rotors and new pads, all round. Is it worth changing the wheel bearing, would this shudder damage the wheel bearing at all?
Any ideas would be greatly appreciated as it needs to be done ASAP.
Also im not sure if slotted rotors is an over kill, its mums and mine daily driver, but isnt driven hard, but we just want to eliminate the problem.

[EDIT] Sorry about the spelling in title, very tired [/EDIT]

[88GreenVN]

Shudder when braking = rotors. Even replaced with $60 cheapies will be better then the (Hang on we want to stop @ 50kph)

If it was wheel bearings they will grumble and probably shudder all the time.

Also I bet the brake peddle polses too

[Tom_1569]

Shudder when braking = rotors. Even replaced with $60 cheapies will be better then the (Hang on we want to stop @ 50kph)

If it was wheel bearings they will grumble and probably shudder all the time.

Also I bet the brake peddle polses too

Yep peddle puslates to.
So the wheel bearing wont get damaged from all the shuddering?

Its definitly the rotors caus when they were machined they were good for 200od k's. To be safe ill be doing pads aswell caus i cant imagine they would be to even after all this shudder shuder shudder shudder lol.

[VrWagz1]

I would go some slotted rotors. My guess its only the fronts causing you issues. It will cost you about $150.00 for a pair and you can get them for less. They are really easy to change as they are only floating rotors, 2 bolts to take the caliper off and the rotor slides straight off.

[Tom_1569]

I would go some slotted rotors. My guess its only the fronts causing you issues. It will cost you about $150.00 for a pair and you can get them for less. They are really easy to change as they are only floating rotors, 2 bolts to take the caliper off and the rotor slides straight off.

Yeah i didnt think they were to hard, mum doesnt trust me, yet i do everything on my car lol. Back ones are the same arnt they, just gotta be careful of the handbrake shoes?

[88GreenVN]

The pads can still be OK if they have lots of pad material on them. When they are out do fig 8's on the concrete to buff them up a bit and get them flat.

Wheel bearings can pit if they are loose - but that will feel more like a wheel balance problem - ie at a particular speed.

[BANKS]

attaboy, azkwazere or not_an_abba_fan, i forget which one lol anyway one of them can sort you out with some rotors slotted and dippled FTW

[knowledge_is_power]

Don't go the ultra cheap front rotors as it is the materials used in the rotor that allow the problem. I suggest something like the DBA rotors, doesn't have to be slotted, just better then the factory item.

Jezz

[Bax]

Yeah they don't have to be slotted, and if you do decide on going the slotted ones don't worry about roughing up the pads on the concrete to tidy them up as the rotors will do that for you.

[Cheap6]

I've seen a lot of theories as to why brake shudder occurs. Holden's idea was that due to a stack up of machining tolerances, between the disc and the hub, discs wouldn't run true and wear in one spot => shudder.

If the disc (or discs) aren't machined accurately then that may indeed be the cause, but not in 200km.

What I think is more likely is that the discs+/or pads weren't bedded in correctly. If the brakes are used hard prior to being bedded and the car is brought to a stop with the pads in hard contact with the disc, pad material is transferred to the disc surface. Not cleaning off the wax or machining oil, or greasy handprints on the disc surface can cause a similar effect. This spot on the disc then a) doesn't bed in properly (the cast iron on the disc surface is changed with the heat of use), b) wears at a different rate to the rest of the disc and c) the change in the friction properties of the disc surface in the presence of the pad material can cause shudder more immediately, which is what I think happened =>

BRAKE PADS NEED TO BE BEDDED IN PROPERLY

(I've professional technicians either ignore the process or do it the wrong way)

[vnv8driver]

simple you have warped brake rotors!!! as mentioned above but didnt see a reason to why its the rotors?

[Raging Bull]

Yeah mine were shuddering pretty bad so I went in and asked to have them machined, now I was more than happy to buy new ones if needed be but they didn't say anything and told me the shuddering would be gone after the machining. It lasted maybe 2 days and the shudder was back, steering shacking etc, what a waste of money. So yeah don't get them machined buy new ones.

[BANKS]

Yeah mine were shuddering pretty bad so I went in and asked to have them machined, now I was more than happy to buy new ones if needed be but they didn't say anything and told me the shuddering would be gone after the machining. It lasted maybe 2 days and the shudder was back, steering shacking etc, what a waste of money. So yeah don't get them machined buy new ones.

Yeah machining them is only a quick fix and to be honest a complete waste of money. The reason for the discs to warp is that there is too much heat build up in the rotors from either a full emergency stop or heavy continuous braking. Because of the heat the disc warps under the extreme pressure from the brake pads, then when it cools it sets in that position. The cause of the issue, heat, goes all the way threw the rotor so machining only gets rid of the superficial damage. The real damage is inside the rotor core where the heat has permanently warped the metal. When the rotors get hot again, they warp back to what they were previously before they were machined.

Only real fix, new rotors.

[Full Spectrum]

You got to be careful getting water into them when hot,
I paid good money out for VP's front rotors, Kangaroo paws slotted!. Performance Bendix pads, Bloody great stoppers..
But after heading into car washes today I'm guessing i was once washing the car and i must have got to much water on hot rotors, Then taking off needing to get some temp back into them just slightly tapping the brake till i had brakes was enough maybe to warp them out.

[Tom_1569]

Thankyou for all your help, it will be new rotors and pads just to be 100%, not sure if its going to be all round or just fronts, and not sure on standard or slotted, but they will be DBA no matter what. It will depend what my mate thinks on getting slotted caus im getting him to get them trade for me.

The bedding in thing, i can say may be a problem after they were machined, as mum never does this, she had to take my car for a roadworthy after rebuilding the front end, i told her a million times, even left notes on the steering wheel. I get back from holidays and ask her if she bed the brakes in, shes like no you never told me to I will be bedding these in for her, anyone have any good tips for bedding in, just lots of light braking without coming to a complete stop?

Raging Bull - Thats what the mechanic told her, he said it was not worth replacing them as it costs more and isnt necasary, he then charger her 45 bux a rotor for machining, we all tried to tell her that it wasnt worth it but she believed the "honest" mechanic. Been trying to talk her into letting me service it and every 5 thousand with proper stuff instead of this idiot who doesnt change filters till every 30 thousand, im slowly getting through haha.

[Not_An_Abba_Fan]

Now the real reason.

On the VT model it was actually worse than any other. The main reason it happens is incorrect tightening and torquing of the wheel nuts.

After machining or replacing rotors, the wheel nuts need to be done up in a star pattern and torqued to 100-125 Nm, if you don't it almost always caused variable disc thickness that gets worse as time goes on. This will make the steering wheel vibrate and the brake pedal pulsate when braking.

Another less common cause is too much lateral play in the wheel bearing. To check this you need a dial gauge.

As mentioned above, I do RDA slotted rotors and have never had a problem with them if the correct torquing procedure is followed.

[88GreenVN]

Now the real reason.

On the VT model it was actually worse than any other. The main reason it happens is incorrect tightening and torquing of the wheel nuts.

After machining or replacing rotors, the wheel nuts need to be done up in a star pattern and torqued to 100-125 Nm, if you don't it almost always caused variable disc thickness that gets worse as time goes on. This will make the steering wheel vibrate and the brake pedal pulsate when braking.

Another less common cause is too much lateral play in the wheel bearing. To check this you need a dial gauge.

As mentioned above, I do RDA slotted rotors and have never had a problem with them if the correct torquing procedure is followed.

There you go - doing the wheel nuts up wrong! Didn't give that a thought as I have only ever done them up in a star patten. But I guess some poeple dont know AND we can all over tighten wheel nuts

[Tom_1569]

Now the real reason.

On the VT model it was actually worse than any other. The main reason it happens is incorrect tightening and torquing of the wheel nuts.

After machining or replacing rotors, the wheel nuts need to be done up in a star pattern and torqued to 100-125 Nm, if you don't it almost always caused variable disc thickness that gets worse as time goes on. This will make the steering wheel vibrate and the brake pedal pulsate when braking.

Another less common cause is too much lateral play in the wheel bearing. To check this you need a dial gauge.

As mentioned above, I do RDA slotted rotors and have never had a problem with them if the correct torquing procedure is followed.

I was going to torque them down, i like torqueing **** down, makes me feel safer and gives the torque wrench a good work out, but didnt think this could affect the shudder but does make sense, especially caus the mechanic always uses the rattle gun for wheel nuts everytime.
Do you still sell the DBA slotted, if so how much would we be looking at roughly?

[Not_An_Abba_Fan]

DBA's are around the $250 mark a pair I think.

[Cheap6]

This is the source for my earlier post:

StopTech : Balanced Brake Upgrades

It's borne out by personal experience. I have, out of ignorance before reading that, destroyed discs in less than 10 mins. of driving.

There's bedding advice also.

[Raging Bull]

Yeah machining them is only a quick fix and to be honest a complete waste of money. The reason for the discs to warp is that there is too much heat build up in the rotors from either a full emergency stop or heavy continuous braking. Because of the heat the disc warps under the extreme pressure from the brake pads, then when it cools it sets in that position. The cause of the issue, heat, goes all the way threw the rotor so machining only gets rid of the superficial damage. The real damage is inside the rotor core where the heat has permanently warped the metal. When the rotors get hot again, they warp back to what they were previously before they were machined.

Only real fix, new rotors.

Exactly right and what ****es me off most is why didn't the bloody "Brake Specialists" inform me of this, I was more than happy to buy new ones instead waste $150 on absolutely nothing, very angry about that.

[burnz]

when on the brake's, pay attenion to the gearstick to see if it move's up and down.
if so replace rear brake rotor's as well.

[Tom_1569]

when on the brake's, pay attenion to the gearstick to see if it move's up and down.
if so replace rear brake rotor's as well.

LOL, Im guessing when i say i dont need to look caus i can hear it moving its time to replace the back ones aswell.
Looks like its going to be 4 all round, maybe just slotted up front and standard on the back. Cheers for that, and everyone elses help, hopefully get this fixed this weekend.

[s_ikari2015]

I'd just like to say the 4 slotted rotors I purchased from not_an_abba_fan have been great. I replaced worn front wheel bearings as well and I haven't had a problem with my brakes at all.

I have felt the infamous VT "square rotors" before in my car and the new rotors are so much better now that they are bedded in. At the same time there was an issue with suspension I had Holden looking at and they were all like "oh boo-hoo, you shouldn't use slotted rotors cause they'll make heaps of noise and vibrations". Well guess what Holden, WRONG! Perfect brakes. :P

[Tom_1569]

Ok Funny **** about getting quotes.....
I went in to sale repco got quoted 123 per a slotted rotor and 58 bux per a pair of pads, also standard rotors 66 each.
My mums partner recons he can better that claiming hes mates with the boss, so he goes in to Sale repco and his quote is 196 per a slotted rotor, and 68bux per a pair of pads, he didnt get a price for standard rotors.
My mate who gets trade price goes into the same store (sale repco) gets quoted 130 a slotted rotor, but only 41 per a pair of pads.
Now im starting to think this is completly messed up, so i tried the traralgon store (still repco) on my way back from tafe.... 111 per a slotted rotor, 78 per a standard rotor, and 54 per a pair of pads.
So i go back to sale and see if they can match that, nope they claim its below cost price, and they advised me to just get them from traralgon as even they saw the savings.
None of this makes any sense, how can i get the cheapest quote over mates rates and trade price haha, except for brake pads.
Anyways to cut a long story short, ill be buying the rotors in traralgon and my mates gonna pick up the pads for me, so all 4 four DBA slotted rotors and a full set bendix pads for just over 500bux, not bad considering the total quote my mums partner got was 900+ and mine was 600+. Definitly pays to shop around.
Sorry for the long post I just found this quite amazing, and yes dont worry I have to much spare time so it didnt affect me one bit shopping around.