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New Drums, New Shoes, NEW SHUDDER!
https://www.ausmini.com/forums/viewtopic.php?f=2&t=79330		 Page 1 of 2
Author:  bigtez [ Tue Nov 27, 2012 7:03 am ]
Post subject:  New Drums, New Shoes, NEW SHUDDER!
Yesterday I replaced the drums and shoes on my car with stepped Cooper S items all round, and now I have a shudder that seems to be coming from the front right wheel when braking.

Obviously I had to remove the drive flange to replace the studs, but as the grease inside still had its original yellow colour I elected not to replace the wheel bearings yet. The brake cylinders also looked as though they had recently been serviced (was told they were when I bought the car earlier this year) so I left them alone for now.

It feels like the drum is not perfectly round, if that is possible. I did note when adjusting the shoes that it would catch at certain points when rotated.

This morning I will put one of the old drums back on and readjust to see if the 'catching' is still there.

Is it possible that the new drum is not perfectly round? What else should I be looking at?

Cheers
Terry
Author:  69k1100 [ Tue Nov 27, 2012 9:41 am ]
Post subject: 
I had a poke around in the seach bar ant the two most common problems are oval or "crowned" drums and the studs not pulling through the hub squarely. Hook up a piece of wire and set it close to the outer drum surface, spin the drum and watch, if the gap closes between the wire and the drum then it's not cocentric anymore.

Edit* if you can feel it through the steering wheel it's the front drums.
Author:  adamstuart [ Tue Nov 27, 2012 10:07 am ]
Post subject: 
When you installed the new studs, did you tighten them home by bolting a wheel on?

Or did you hammer them home?
Author:  9YaTaH [ Tue Nov 27, 2012 10:17 am ]
Post subject: 
all of the above are possibilities...and I would suspect the new shoes....

they often have high spots on them and need bedding in...when you remove the drum you may see a furry part (the low or high spot) and elsewhere, mostly shiney friction material

also may be too fat??
Author:  bigtez [ Tue Nov 27, 2012 10:17 am ]
Post subject: 
I put the flange in a vise, used an old socket as a spacer and pulled them in with the old wheel nuts. The only hammering I did was to tap out the old studs after they had a good soaking of inox.

When I undid the castellated nuts they were both very tight, however I only did them up to 60ft/lbs. Should I have done them up as tight as the previous gorilla did?
Author:  9YaTaH [ Tue Nov 27, 2012 10:19 am ]
Post subject: 
bigtez wrote:
I put the flange in a vise, used an old socket as a spacer and pulled them in with the old wheel nuts. The only hammering I did was to tap out the old studs after they had a good soaking of inox.

When I undid the castellated nuts they were both very tight, however I only did them up to 60ft/lbs. Should I have done them up as tight as the previous gorilla did?


I'm thinking YES! :!:
Author:  drmini in aust [ Tue Nov 27, 2012 10:39 am ]
Post subject: 
There have been cases recently of some new drums being oval inside.
This happens when the castings are not aged enough to reduce stresses, before machining.
In the old days they left them to weather for weeks or months, these days they `age' them via heat treatment instead. Sometimes the Chinese/Indians get this step wrong...
Author:  adamstuart [ Tue Nov 27, 2012 11:12 am ]
Post subject: 
bigtez wrote:
I put the flange in a vise, used an old socket as a spacer and pulled them in with the old wheel nuts. The only hammering I did was to tap out the old studs after they had a good soaking of inox.

When I undid the castellated nuts they were both very tight, however I only did them up to 60ft/lbs. Should I have done them up as tight as the previous gorilla did?


60ft/lbs is correct I believe.

It's the cooper S drive line that is 150 or so. People tend to thing "If the race version is 150, I'll do mine to 150 too!"
Author:  bigtez [ Tue Nov 27, 2012 3:14 pm ]
Post subject: 
After putting the old drums back on and adjusting them, I found they still caught the shoes in one place. So I would assume the issue is the drive flange and new studs not being quite right.
Author:  mini_mad_matt [ Tue Nov 27, 2012 3:51 pm ]
Post subject: 
Are you using the 2 locating screws in the drum? If you are, try without them.
Author:  drmini in aust [ Tue Nov 27, 2012 3:55 pm ]
Post subject: 
How did you fit the new studs, if you bashed em in they may be bent or crooked....
Or maybe the new aftermarket studs are not of Original Mini Quality (ie, straight).
Author:  bigtez [ Tue Nov 27, 2012 4:45 pm ]
Post subject: 
I did this doc:

bigtez wrote:
I put the flange in a vise, used an old socket as a spacer and pulled them in with the old wheel nuts. The only hammering I did was to tap out the old studs after they had a good soaking of inox.


I just pulled the flanges off again and repeated the above process to ensure they were all seated properly. On close inspection it appears one stud may not be seated square to the flange, or the head may just be slightly fatter on one side, its hard to tell. However after a short test drive, it is significantly better but still not perfect.
Author:  bigtez [ Thu Nov 29, 2012 10:16 am ]
Post subject: 
So..... I ended up replacing the drive flange with the 'crooked' stud with a second hand flange, and had some improvement. Most notably the drum now rotates without catching the shoes.
As the issue was still there I decided to investigate a little further and have found one of the balls in the inner CV (or is it a slip joint?) was floating around loosely. So before I do anything else I will be checking and re-assembling the joint.
Author:  peterb [ Thu Nov 29, 2012 6:43 pm ]
Post subject: 
Hmmm, one of your balls fell out :shock:

Seriously but, the ball falling out cv shouldn't affect brakes. Usually, if that happens you get shudder under accelleration. Try swapping 'suspect' drum to another wheel, say back, see if problem follows.
Author:  GT mowog [ Thu Nov 29, 2012 7:36 pm ]
Post subject: 
drmini in aust wrote:
There have been cases recently of some new drums being oval inside.
This happens when the castings are not aged enough to reduce stresses, before machining.
In the old days they left them to weather for weeks or months, these days they `age' them via heat treatment instead. Sometimes the Chinese/Indians get this step wrong...


I've also been supplied a number of new ones that had the register machined over-size and so don't locate positively, ie they flop around a bit on the hub :twisted:
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