New brake linings a very tight fit.

[rogerowen]

Just put a new set of brake linings on 7" front brakes. Even with adjusters fully off, the drums were tricky to get on and I can only turn the drums with the wheels on. I haven't bled the system yet but I'm concerned about how tight they are. I cleaned the drum contact area and measured the width of the new linings in case they were a little wider than the old ones and running against previously un-worn ridges - but they are the same size. N/S wheel is extremely tight and when I pulled the drum off again to check I could see that the drum was rubbing on the first few mm's of each lining (both leading and trailing). They do have a champfer running back around 2mm, but the drums seem to be rubbing against the next 2mm after the champfer.

Question; should I file a bit more of a champher on the linings or just let them bed in naturally? Anyone had experience with this?

Cheers,

Roger

[Tom and Maria]

Are they properly seated on the opposite end to the cylinders?

If you can turn them with the wheels on fairly easily I shouldn't worry. Give it a run, if the hub caps get unduly hot it might be worth taking a little off the surface, if not, they'll bed in nicely.

Tom

[MarkyB]

Some more chamfer wont hurt.
It's worth giving the shoes a tap on the metal part with the drum half on to help centre them.
Otherwise some jabs on the brake pedal with the drums fitted can centralize them too.

[mike.perry]

Check that the wheel cylinder pistons are fully retracting. Get a screwdriver between the shoe and the backplate at the top and bottom and lever the shoes up/down.
When fitting the drums tap the shoes sideways until the drum fits over them then tighten the drums on with two diagonal wheel nuts, NOT the retaining set screws.
Press the brake pedal hard a few times to centralise the shoes

[lowride stepside]

Tight is always better than baggy

[kennatt]

bleed the system ,so you can use the brake ,you will probably find that once the brake is applied it will centralise the shoes,its not realy possible to do this any other way .and the shoes will be off centre otherwise.If they are still too tight and you are certain that everything is the right place,simply file a bit of the metal from the rounded end of the shoe to give more clearance,just a few strokes of a file should do it,the shoes are a copy of a copy of a copy ,like everything else not exactly the same as original.Be thankfull its not the other way,many on here have reported having to shim the shoes because they can't get full adjustment because they are too small

[rogerowen]

Excellent advise, thanks all.

Have a feeling it's a manufacturing tolerance fault either in the linings or the new wheel cylinder I have fitted - Yes, it's a lockheed rather than a £5 cheaper pattern one (I now understand they are prone to leaking - not good!).

However, when fittng a new Lockheed master cylinder recently I found that I had to take off an eigth of an inch each side to get it back to the width off the original so it would fit.

Filing the metal brake shoe a tads should do the trick.

Cheers,

Roger

[Declan_Burns]

However, when fittng a new Lockheed master cylinder recently I found that I had to take off an eigth of an inch each side to get it back to the width off the original so it would fit.

Roger,
I had the same issue and a mate of mine too.
Regards
Declan

[rogerowen]

UPDATE:
I've re-fitted the brake drum and wheel and managed to force it round a few times. After taking the drum off again I found stress marks at each edge of the brake linings. I've filed them down, re-fitted road wheel and forced it around a few times (very tight - even with the adjusters fully off). Now done this several times and drum still very tight. Tried centralising several times - but that's not making a difference. These are original 7" brakes - now wondering if I've been sent 8" linings by mistake, but then would 8" linings even fit in a 7" drum???

[kennatt]

Measure the shoes round the outside,or compare with the old ,did you fit new adjusters the 8" brake adjusters have slightly larger profiles,do you know the history of the old brakes,could someone have fitted the larger adjusters to compensate for lack of adjustment on the old worn shoes.Compare the adjusters with the rears which were all 7",

[mike.perry]

Are you sure that the pistons are fully retracting? The top of the piston should be flush with the top of the cylinder
Have you got the springs in the correct holes for giving maximum tension?

[rogerowen]

Yes to all recommendations, and old linings fitted without a problem, plenty of adjustment and not heavily worn (only replacing cos soaked by leaking pattern wheel cylinder that had only given 7 month service!). Just going take some measurements.

[bmcecosse]

Compare the shoes with the old ones..... you may need to deepen the slot which fits the adjuster (they do both have slots ??? Rear shoes don't....) - few strokes with a round file should do it - or take a small amount off the tail mount of each shoe.

[rayofleamington]

you may need to deepen the slot which fits the adjuster

takes a split second with the angle grinder...
I've had to do some fettling on all the new brake shoes I've had over the last 10 years.
Another common problem is that the shoes are a bit undersize (opposite problem) AND prevent the adjuster from fully rotating. This can also be fixed with the angle grinder..

[rogerowen]

Thanks for the tips. As I could see that the stress marks were only on the leading and trailing edges of the new shoes - I've concluded that the linings must be either fatter at the ends or the curve of the shoe is slightly less than the drum. I did measure them against the old shoes and could not make out a curvature difference, but noticed that the new linings were about 1 inch longer than the old ones. In the end I've opted to filing the lining material at the edges several times (noticing that the stress marks were begining to move towards the centre), after about 8 sessions the drum was less tight and I decided to road test the car. The brakes worked well and straight. Hubs got a little warm, but not alarmingly so. Adjusters still fully off, but happy enough to let them bed in further and adust as they start getting slacker.

[rayofleamington]

Be careful when the hubs are getting hot, as this means the brakes are hot.. which means you are much closer to brake fade.

However, on the flip side the extra heat & friction does mean that the shoes will bed in more quickly. The brakes will only reach full efficiency when the shoe material has worn to the same curvature as the drum. I always over adjust the brakes with new shoes fitted to speed up the bedding-in process (not advice, just an anecdote) and not had problems so far.

[rogerowen]

Thanks Ray, will pop the drums off and have a look at the weekend.

Cheers,

Roger

[bmcecosse]

As long as the car rolls freely on a level road - and pedal travel is acceptable. They will be fine.

[rogerowen]

UPDATE:

After taking the drums off several times and filing more and more off the lining material - I've given up! Linings are still only contacting at the ends and there is no wear to the centre portions. Ergo - they continue to squeel, graunch and vibrate. Have decided to buy new drums and new linings and try again. Have never had this kind of problem before.

[bmcecosse]

beware - some of the new drums have been known to be less than perfectly made. Sounds like your drums have perhaps been skimmed out oversize? Have you tried USING them really hard over and over until they fade out.