Low speed "tug" on bars?

Chamelespoon · Post by **Chamelespoon** » Fri Sep 03, 2004 1:30 pm

Hello, all!

Bought my S a couple of months ago (2000 model Silver/Mandarin with ABS, 1600 miles on the clock), and have recently started noticing that at very slow speeds (sub 15 mph), usually under braking, I'm getting a noticable, repetative tug to the left through my bars, about every second or two. Not strong enough to upset the bike, but enough to make me curious.

I've taken a look at the front end - tyres, brake disks, wheel rim, wheel alignment - but everything seems to be okay; can't see anything that would account for it.

With the S being my first Boxer, I wondered whether it might be something to do with the engine's "character" at low revs, but the tug doesn't seem to be rev dependant (albeit using my highly scientific method of trying to keep the throttle cracked open while braking with the clutch in...

).

So... is this normal? Has anyone else experienced this? If not, any ideas what could be wrong?

Oh, and it's not the road surface either!

I'm having the tyres replaced at Pidcock's on the 11th (oh, any advice on the best "ride in, ride out" tyre place near Derby?), so I'll get them to take a look at it then, too, if you guys think there's cause.

boxerpan · Post by **boxerpan** » Fri Sep 03, 2004 2:08 pm

It sounds like the usual pre 2001 issue with the mounting of the discs to the front wheel if its happening under brakink. More knowledgable folk than me will correct me if I'm wrong but as far as I know ;
The front discs are mounted direct to the soft wheels and the shoulder where the two meet wears away with usual use and the discs start to move about as you brake. Later models from 2001 year on have shims/washers behind the disc to stop the interference and this can be a retro fit if the shoulders on the wheel aren't too worn.
If you do a search for front disc you'll come up with all the previous history of other members trials and tribulations.

Chamelespoon · Post by **Chamelespoon** » Fri Sep 03, 2004 3:27 pm

Thanks, Lloyd. Not sure that's the problem I'm getting (from what I've read it's on pre-2000 bikes, and should only occur after 30-40K miles), but it certainly gives me something to have a look at, and the more I can get fixed while within the 12 month Pidcock's warranty the better.

boxerpan · Post by **boxerpan** » Fri Sep 03, 2004 5:05 pm

If the brakes have Brenbo in raised letters on the outside of the caliper then you have the earlier brakes that this problem is common on. Uprated brakes (I think from model year 2001) just have BMW on the outside of the calipers.
16 hundred miles on a four year old bike ??? Probably seized up from lack of use

gus · Post by **gus** » Fri Sep 03, 2004 6:29 pm

Sounds like you may have a warped disc,most likly the left if its pulling that way.
If discs(s) are true,then maybe a caliper clean up is in order.
gus
welcome to the fold.

Merecat · Post by **Merecat** » Fri Sep 03, 2004 6:49 pm

Welcome
Sounds like a classic nearside caliper drag. Mine did it at just over 800 miles. The only water that had been on it was from washing the thing!! It needs a good clean and greasing, back of the pads only ,of course

I think that if it was tyre related you would feel it more at higher speeds.

Tyres in Derby?
I have used Inner ring tyres for loose wheels they're somwhere up near pride park.
I had my 020s fitted by Grippers in Swadlincote 01283 552837 Ride in Ride out. Not the cheapest, but convenient for me and the bolox they talk is of the highest quality.

Mick

Boxertools · Post by **Boxertools** » Fri Sep 03, 2004 7:02 pm

For the information of all those interested, last year I did a track day at Cadwell and a bloke local to me (Kings Lynn), binned his Y reg mandarin & silver s.
I think It should have been written of. The cost of repair was apparently £1800 I can't remember if that is what it cost him, but is was back on the road and an unsuspecting buyer, would have no idea of its history.
He by the way ended up in Louth hospital & then LIncoln. I think he had 6 busted ribs & a broken colar bone.
It was his first track day and neadless to say, his last.
I was there in my van & brought the pieces home with me.
Mike.

Chamelespoon · Post by **Chamelespoon** » Sat Sep 04, 2004 12:39 am

boxerpan wrote:If the brakes have Brenbo in raised letters on the outside of the caliper then you have the earlier brakes that this problem is common on. Uprated brakes (I think from model year 2001) just have BMW on the outside of the calipers.

Yup, you're right, Brembos on here and washers only on one side of the disk. Will have a word with the guys at Pidcock's when I take it in next week.

boxerpan wrote:16 hundred miles on a four year old bike ??? Probably seized up from lack of use

Yup, quite a find, and at just the time buying an S had finally become a possibility from a dream. Something was smiling on me that day, anyway!

Chamelespoon · Post by **Chamelespoon** » Sat Sep 04, 2004 12:53 am

Thanks gus, Mick - you're confirming what I was suspicious of. How obvious would a warped disc be? Should be plainly visible while on the bike, or would it require removal and inspection to tell?

Either which way, it's nothing major (at the moment!), and isn't even noticable above ~10mph, so I'll just get Pidcocks to have a good look when I take it in. Hopefully they'll be able to sort it same-day, else I'll have to leave it until I get back from France (really looking forward to trying the S around Mont Blanc!).

Thanks again for all the help, guys.

Oh, and thanks for the tyre place suggestions, Mick. I'll give them a whirl when I need some replacements.

Rob.

boxerpan · Post by **boxerpan** » Sat Sep 04, 2004 7:05 am

The extent of warping can be measured by clamping a dial gauge to the appropriate fork leg and spinning the front wheel. The gauge measures the run out of the disc over a revolution.
If this is the problem try and get the discs/calipers sorted b4 you go do any mountain hairpins, it'll only get worse.

Chamelespoon · Post by **Chamelespoon** » Wed Sep 08, 2004 10:16 am

Well, I found the problem.

After speaking with my father at the weekend, he pointed out something rather fundamental that meant it couldn't really be a problem with the brakes at all: if caliper drag or a warped disk started pulling the bars to the left, surely that would mean a bike with a single disk on one side of the wheel (a la my old CS) would constantly pull to the side under braking?

I can be somewhat thick at times, it would appear!

Anyhow, it seems my check of the front tyre hadn't been all that thorough, as last night while having a good look at it at the point the "tug" seemed to occur, I noticed the left side of the tread was stepping quite badly... and the right side was forming a noticable lump!

Strange that it shouldn't be noticeable at speed, but it could be producing an extra bit of vibration that I'm simply not aware of being new to the bike. Anyhow, I'm getting the thing replaced on Saturday anyway - hope it lasts that long; will have to take it easy, I think! - so hopefully the problem will go away (and maybe the vibration that sends my throttle hand to sleep too!).

But thanks again for the help, guys; I'll doubtlessly need it again at some point in the future.

boxerpan · Post by **boxerpan** » Wed Sep 08, 2004 3:41 pm

A quick balance of the throttle bodies should banish most of the 'white finger syndrome'.