Juddering at speed

[madbsc]

Hi All, I have a juddering noise at around 70 mph, but it comes and goes.

I was overtaking a lorry 70mph and suddenly sounded like the exhaust was blowing, then as the sound got louder the steering wheel started to judder like the wheel was out of balance. I slowed down to 50mph and it all dissapeared again, I sped back up to 70mph no worries for threst of the day.

On the way home again at 70mph ish I got the same noise and the noise got louder, the juddering got worse, to the extent that I thought I had a puncture.

I pulled over and checked tyres, both ok, no bulges, punctures, nothing obvious but a smell of burning brakes.

Pulled away again and tested brakes with a sharp pull up, no pulling to either side and worked good including anti-lock. Sped back up to 70mph again all ok for rest of my journey home.

Has anyone got any ideas what the hell is going on, or had similar experiences?

 

[Chrisbee]

whee is out of balance or a warped brake disc maybe

 

[madbsc]

Thanks, but the juddering dissapears again once I had stopped to check the car. I had thought about it being the disk, but I would have expected to feel some juddering through the pedal, or pulling when I pull up sharp, besides I had new disk a few months back.

It's a bit of a mystery, cause I used the car again and had no noise or juddering and covered about 50 miles that day.

Weather permitting, I plan to get the car on the ramps this weekend and have a look to see if I can find anything.

 

[Chrisbee]

It could be a sticky caliper also, especially if the cars sat around for a little while.

I had something simular with mine but the car would sometimes pull to one side.

It could also be something to do with the throttle, as it is an electronic throttle so it could be developing a fault. (if it is a later model?)
worth sticking it on a scanner to see if any codes pop up

 

[madbsc]

Thanks for your input Chrisbee.

That is something I hadn't considered, will give that some thought and mabe check VAG.

I had it up on ramps weekend and checked out calipers, wheels spin freely so just leavered pads open and pumped brakes again, still spin fine no probs.

I thought it could be wheel bearing, but no sideways movement or roughness when turning by hand and quiet when driving below 70mph.

I drove it again today and was fine until I drove for a while at 70 ish, then it started again, so I slowed down to 60mph and all was quiet again. I was concidering one of the CV joints may be giving up, maybe it is running dry and getting stiff when hot.

Sounds like a droneing then gets louder and steering wheel starts to shake like a weight has fallen of the wheel and its gone out of balance.

Thanks for your thoughs on this one.

 

[madbsc]

Update

Hi All, I have now solved the problem of the juddering.

Working on the idea that it could be the brakes sticking on, I started to think about the Copper Slip that I had used on the caliper pins, when I replaced the disks in october.

I did a little research on the net about Copper Slip/grease and mainly it was posative, in that it was the right thing to use on brake parts, because of the heat and all. I did find a couple of negative comments about Copper slip and how it dries out to leave a thick paste, so I thought I had better check this out.

The weather was a bit better this friday so I took the calipers of and had a look and the pins had dried out making the brakes stick and drag. I cleaned the pins of and greased again with high temp grease and put them back together. No problems or juddering anymore.