Steering shaking on braking

[Wildfire]

My E86 seems to have developed a steering shake on braking from over 50mph. It become more pronounced if you brake hard.

It feels as if it's coming from the front left.

I've replaced the lollipops around 15k ago with Meyle HDs and fitted new discs and pads when it occurred, but it seems to have come back now.

I've checked the wheel balance and the discs etc. are all good.

Any ideas? Could I have a damaged wishbone?

 

[Paulr]

Had this on my Santa Fe and my caliper had seized one side, distorting my two year old discs. it does sound like your discs though - does it pulse on lighter braking?

 

[ph001]

It could just be uneven pad deposits on your discs. Best way to resolve is to redress the discs by rubbing down with 400 grit silicon carbide wet and dry and follow the correct bedding in procedure for the pads (likely to be a few hard stops from speed). If that doesn't work, most likely to be a warped disc (particularly if they were budget ones). Replace or if they were premium discs, just get them skimmed (about £15 ech). Good shout on making sure your calipers and pistons move freely on each side.

 

[Joycey]

My moneys on a sticking calliper if you can feel it in the wheel, I've had this very thing recently.

 

[tomscott]

That or a warped disc.

If its a sticky caliper the vibration will be all the time and get worce the faster you go.

I have a sticky caliper the car literally felt like it was trying to rip the steering wheel out of my hands. Had to have a new one with disk and pad. Thankfully under warranty.

 

[mr wilks]

Decent 15-20mins drive with plenty of braking then have a touch of each front caliper , should easily identify if one is sticking .
As mentioned already it could be warped disc & also worth checking tyre pressures on front ( ideally 32-34psi)

 

[Wildfire]

Right, I'll try and get the wheel off next weekend and clean down the calipers. I just hope it's not a worn bush or something.

The car doesn't get used too much at the moment.

I've got a infrared thermometer some where, so I may give that a shot too.

 

[Wildfire]

Had this on my Santa Fe and my caliper had seized one side, distorting my two year old discs. it does sound like your discs though - does it pulse on lighter braking?

Only from about 40-50 mph. But at higher speeds, yes. Light pulsing, then progressively more violent the harder I brake.

 

[buzyg]

I would agree this sounds like a sticky caliper. The sticking one will be getting hotter sooner, so you should be able to easily confirm if that is the case. It may well have all ready done some damage to your discs and pads, if it's not bad then they will clean them selves up over a few drives. Otherwise you may need to get them skimmed or replaced too.

 

[Wildfire]

Hmmmm... So I take it that it is caliper off, clean the pistons up and the sliders.

 

[Mike6]

My money would be on a warped disc but that seems less likely if they were replaced not that long ago. So sticking piston in the calipar has to be the next thing to look at. However replacement discs can be dodgy if you purchased them off the internet. Do they have a large groove around the outside of the disc. If so I wouldnt discount disc failure or possibly broken brake pad material. Should be easy to check.

 

[Smartbear]

Hmmmm... So I take it that it is caliper off, clean the pistons up and the sliders.

It’s not always that easy, the machined recess in the calliper the piston seal sits in can corrode behind the seal & push it against the piston.
Cleaning the piston up if this has happened will be ineffective :thumbsdown:
Rob

 

[ph001]

I think a strip down, clean and application of copper grease on the sliding surfaces is what I would do as a starter. I warped a pair of discs on my Z3-M doing an 'emergency brake' from 150mph to 70mph on the Autobahn (twat in a Fiesta pulled into outside lane whilst I was gunning it). I guess the discs went from approx 30'C to 300'C in about a second!

They were never right after that and I had to get them skimmed.

 

[patriot66]

This is highly likely to be a warped disc/discs. I fitted new M-Tec Grooved discs and Red Stuff pads back in April and warped them whilst on the Dumfries & Galloway run. I took my Zed to Suthers Star Garage in Walmer Bridge, Preston as they have a Procut On-Car Brake Lathe and can resurface warped discs whilst fitted on the car so that both faces on the disc are parallel and true to the hub. Also it is highly unlikely that a disc that has been heat cycled, warped and had its grain structure altered will ever warp again even after skimming. Mine have been perfect since I had them skimmed. Take a look here : http://skimmydiscs.co.uk/

 

[Ebeneezer]

First thing I would do is take the car out somewhere where you can do some high speed braking to clean any pad transfer off the discs, I have to do this every now and then with my car on M-Tec drilled and grooved discs and Ultimax pads. Also Don't use copper grease on the sliders, use a clear spray grease.

Tony.

 

[jestn7]

Another source of vibration when braking can be worn Lower Control Arm Bushings. This repair can be expensive (mostly labor), about $700 USD.

 

[Wildfire]

Hmmm... I'll whip the caliper off and clean it all up, then see what happens. Or maybe I'll go for a re-build kit.

 

[Wildfire]

Another source of vibration when braking can be worn Lower Control Arm Bushings. This repair can be expensive (mostly labor), about $700 USD.

I've replaced these. Luckily my dad has a workshop. Cost me £120 last time.

 

[Wildfire]

Ok update:

Had a look today, both brakes are fine, spin freely. I can’t see any major issues at the moment. Disc and pad wear all looks good.

Unfortunately I did lose the small clip that holds in the wear sensor and may have damaged the wear sensor as the light is now stuck on!

New wear sensor to go on tomorrow, then back to the drawing board.

Any ideas before I send it in to my mechanic?

 

[ph001]

You can't easily see uneven pad deposits or measure warpage without a dial gauge. I would have re-dressed the discs as mentioned before. If no improvement then have discs skimmed or replaced. All very easy diy tasks.