Front Brake Shuddering

[ruSTyEB]

Ever since replacing my front wheel bearings I have a strong shudder when applying the front brakes.  Before bearing, there was a very small shudder, but nothing concerning.  The shudder occurs when I apply hard braking to the front, but the shudder is barley noticeable when applied softly.

Could the bad front wheel bearing have been masking a rotor issue?

My untrained eye can't see any obvious warping or glazed spots on the rotor.

Recent work on the front end includes head bearing, fork seals (sliders bushes and oil) and wheel bearings.  Of which I took the front wheel off myself and put it back on. Maybe I got something wrong?

So before I buy new rotors, are there any suggestions on a fix?  I'm guessing not doing anything will lead to other problems down the track.

Or would I be better having existing rotors machined? There is a noticeable wear track on the rotors where the pads contact.

Some rotors I've found online at a decent price:
http://www.s3performance.com.au/buy/disc-brake-rotor-front-honda-st1100-shadow-triumph-900/DBFSST1192

Any advice greatly appreciated.

[Biggles]

Here's a reference that may help:

http://www.st-owners.com/forums/showthread.php?120518-ST1100-front-brake-shudder

[ruSTyEB]

Thanks for the reply Biggles.  I`ve read this post, I was hoping someone had experienced shudder and resolved it without the need for new rotors.

Last thing need right now is to fork out $200 and it doesn` fix the issue.

[saaz]

You could try giving the rotors and pads a clean with something like brakeclean (even give the rotors a rub with steel wool or something), then lightly rub the pads to deglaze them.  Then run them in again.

I fixed a similar issue with some new rotors that would not bed in properly. I used some old sintered pads I had that were more aggressive, and they bedded in the rotors better.  Then I put the new pads back in.

[Biggles]

Last thing need right now is to fork out $200 and it doesn` fix the issue.

Ah, but you'd have a spare pair of rotors, and they do need replacing after 100,000+ km.

The rotors are really the most likely cause, and saaz's suggestions might solve the problem.

[ruSTyEB]

Thanks guys,  looks like new rotors it is.   From the condition of them I'd say tthere never been replaced making them 166000km olold.

[Biggles]

Thanks guys,  looks like new rotors it is.   From the condition of them I'd say tthere never been replaced making them 166000km olold.

We might have stumbled upon a cause here...     


Din't complain.  When I got my St11 inspected for its sale roadworthy they required new rotors because they were worn below spec.  I didn't know about after-market rotors and forked out $900 for 3 rotors and linings.     

[ruSTyEB]

Purpose of the post was to see if there could be other causes other than rotors.  New rotors was the default fix and as no other opinions given ill take that.

My original post asked if having refitted my own wheel after bearing, could it have contributed to shudder...It seems no.

Yes the rotors look old, but how old? I`m just guessing because i have never had a vehicle long enough to have rotor wear.

Unfortunatly i don`t have a guage to measure to rotors wear or run out. and they passed a road worthy only 10000k ago.

So what i can take from this is previous work on front end is irrelavent,, and i`ll be ordering new rotors. Thanks all.

[Brock]

could be a smooth spot on the rotors, glazed pads, a slight high spot or a combo of any or all, or even, maybe a slightly loose headstem bearing, Maybe give the nut a slight tweek.

Front end jitters of any sort on a bike can be difficult to locate.

[Biggles]

Unfortunatly i don`t have a guage to measure to rotors wear or run out. and they passed a road worthy only 10000k ago.

Not every roadworthy inspection checks everything. 
IIRC the limit is 4mm, and the rotors don't come with very much fat on them.

All the things Brock mentions can contribute- I think you've eliminated most of them from what you said in your first post.
The odd thing is, just wearing down the rotors shouldn't induce shudder, but if there's another factor such as uneven wear, out-of-true or a glazed spot, then only a replacement will fix it.  There's no metal left after 100,000 kays to have them machined, and in any case the cost of machining is wasted if it doesn't fix it or only leaves you a year's worth of wear.

[ruSTyEB]

  Brock
  Biggles

[ruSTyEB]

...
New S3 front rotors went on today.....Magic!

Front end behaves very well now, I'll post a pic when I can.

Whilst doing this I noticed my front wheel has spacing for what looks like the ABS senor ring (I'm 1994 ST1100R non-abs and don't have that ring)  Was wondering if there are two different front wheels, one for ABS and one without.  Previous owner did have a prang, and front wheel replaced so that might account for it.

Only really asking because the S3 Performance website has rotors for non ABS 1989-1999 and a different part number for ABS models 1992-1995.  If I happen to have an ABS front wheel, the non-ABS disc has fitted perfectly, so what is the difference? Maybe nothing.

[alans1100]

...
New S3 front rotors went on today.....Magic!

Front end behaves very well now, I'll post a pic when I can.

Whilst doing this I noticed my front wheel has spacing for what looks like the ABS senor ring (I'm 1994 ST1100R non-abs and don't have that ring)  Was wondering if there are two different front wheels, one for ABS and one without.  Previous owner did have a prang, and front wheel replaced so that might account for it.

Only really asking because the S3 Performance website has rotors for non ABS 1989-1999 and a different part number for ABS models 1992-1995.  If I happen to have an ABS front wheel, the non-ABS disc has fitted perfectly, so what is the difference? Maybe nothing.

Just comparing part numbers between 1100R and 1100AR it seems the wheel set is different and disc rotors are the same The difference due to ABS ring etc. If it all seems to fit then you probably have a wheel from the AS model (95 ABS)

But if you have a later ABS (96 or AT model or newer) then the wheel bearings are different, disc rotors are different to suit the 3 pot calliper, the wheel is a little wider and the speedo drive is different to suit the 120/70 tyre.

[ruSTyEB]

Just comparing part numbers between 1100R and 1100AR it seems the wheel set is different and disc rotors are the same The difference due to ABS ring etc. If it all seems to fit then you probably have a wheel from the AS model (95 ABS)

But if you have a later ABS (96 or AT model or newer) then the wheel bearings are different, disc rotors are different to suit the 3 pot calliper, the wheel is a little wider and the speedo drive is different to suit the 120/70 tyre.

 
When I had the front bearings done, Honda used part 6004 (pre 1996)  and the front tyre is a 110/80
So a pre 96 ABS front wheel it must be.
Thanks for looking that up.