Banging Suspension

Post by **57traveller** » Thu May 13, 2004 8:56 am

[quote="Matt"]hmmm i have a bump stop on one side, but not the other.......

Possibly an MOT problem having one missing Matt. An advisory at least.

Post by **rayofleamington** » Thu May 13, 2004 11:32 am

- for instance I have one new and one old drum at the front of my minor. This causes no problems

Chris - you've lit the touchpaper now regarding the brakes!

From a technical point of view I would say that is dangerous. (a complete different league to changing 1 rear spring).
The amount of metal left on the drum, and also the insulating layer of corrosion around the outside affects the heat capacity, so if your coming down a windy mountain pass (for example...

) one front brake will be red hot and the other only medium. Heat changes the coefficient of friction on the lining (the cause of brake fade). Front brake balance is what causes a car to do a 180 spin in an emergency stop! If it was the rears it's far less of a problem
When I was a pizza delivery guy

one of the delivery cars had a sticky front caliper. causing 1 front brake to be hot and the other cold. It was booked in to be fixed as soon as possible and the parts were on order, but before it got done the car had been written off....
I was the one who'd noticed the brake imbalance that only came after hard driving, and I'd refused to drive it again - Therefore it wasn't me explaining to the police how I'd hit an oncoming vehicle whilst stopping on a straight road.

It's your choice and there's a lot worse things you can do, but at least you can make an informed choice on it.

Post by **pskipper** » Thu May 13, 2004 12:15 pm

Minerva has just failed her first MOT, one of the failure points was uneven braking which was caused by new cylinders on one side and old on the other, the old cylinders just couldn't keep up. (My own fault for ignoring everyones sage advise). As I'm now under a deadline (moving in a couple of weeks and loosing my storage space) I've had to get them done by a garage.
In case anyones interested

my 6 months labour reduced the failure list to a 20% imbalence in the front brakes. Front trunnion top rubbers needing replacing, some welding (where I hadn't been able to reach & a couple of small holes I hadn't spotted) and the headlamps were out of alignment! I'm currently getting the welding done at a local garage, the guy has some experience with Moggies (or Morries as he calls them being antipodean), and then she'll go in again either this weekend or next depending on how long the welding takes! (Hopefully she'll pass this time).

Post by **salty_monk** » Thu May 13, 2004 1:26 pm

Agree with Ray (personally I would always go for pairs of new ones - brakes are dangerous!) but I guess you could get away with it on the front if you can find ones that are worn almost identically... If you measure the thickness of the braking surface of the drum & it is within a few thou wouldn't this be good enough?
The other thing to consider I guess is how enthusiastically the car is driven & in what conditions... with one person up around town "pootling" around I guess the brakes won't get hot enough to show any difference, however with 4 up & Ray pushing 80mph it's a different matter

I definitely have different ones on the back of mine as one has two holes to find the adjuster & one only has one... Again as Ray says, I'm not so worried about the rears, front's are defo the most important bits!
Changing all cylinders at once on ours for exactly the reason Philip states above, you'd probably find that the weak ones would give up soon enough anyhow....

Post by **Benjy** » Thu May 13, 2004 2:54 pm

So should we all go fit heatsink style fins to the outsides of our brake drums? It works for vented discs (well OK they're quite on the outside).

Post by **Matt** » Thu May 13, 2004 3:27 pm

57..... Its passed 4 MOT's (at 3 different garages) with a missing rear bump stop....

Post by **57traveller** » Thu May 13, 2004 4:26 pm

My saloon failed for a missing front bump stop and at another testing station my Traveller received an advisory for a missing rear. Personally I'd rather have this and know the tester is doing the job properly. On both occasions the testers were older persons, one had served his time on BMC cars and the other had worked at a Morris dealer in the past. So not just a couple of fly by night kids whose only claim to fame is a MOT testers course certificate.

Post by **rayofleamington** » Thu May 13, 2004 4:38 pm

So should we all go fit heatsink style fins to the outsides of our brake drums? It works for vented discs

nope - just go for vented disks

Post by **Matt** » Thu May 13, 2004 4:41 pm

The guy that does our cars is good, he will show you exactly whats wrong, he did give an advisory for the missing rear tho (and gave 5 free retests......don't ask, it just got silly!)

Post by **57traveller** » Thu May 13, 2004 4:52 pm

Sorry Matt, I'm getting confused

. The front bump stop on the Traveller was an advisory, it failed at the time on a bit of chassis leg corrosion

now sorted. Your tester is probably correct then just advising. I don't think a missing rubber is an automatic failure.

Post by **Chris Morley** » Thu May 13, 2004 9:46 pm

Chris - you've lit the touchpaper now regarding the brakes!
From a technical point of view I would say that is dangerous. (a complete different league to changing 1 rear spring).
The amount of metal left on the drum, and also the insulating layer of corrosion around the outside affects the heat capacity, so if your coming down a windy mountain pass (for example... ) one front brake will be red hot and the other only medium. Heat changes the coefficient of friction on the lining (the cause of brake fade). Front brake balance is what causes a car to do a 180 spin in an emergency stop! If it was the rears it's far less of a problem

A bit melodramatic I think Ray

- my 'old' drum has got plenty of life left in it and the wear groove is a small fraction of 1mm. There's likely to be hardly any difference in the heat sink ability compared to the (two year old) newer drum. Brakes are an area where I don't use worn components and only fit Lockheed original cylinders.

As for doing 180 degree spins due to badly adjusted brakes? It won't be happening to me because I adjust my brakes every 3 months or so. I make sure that there isn't a pull to one side by testing the car on a wide empty road after every adjustment - starting at 20mph (hands off the wheel) and building up to a emergency stop from 60 mph in 10mph stages. That's the only way to ensure your Minor is safe. This is why I always question people who think their brakes are bad as Minor brakes are perfectly effective when properly adjusted.

As for going down mountain passes? Best done using the engine braking I guess...

Post by **rayofleamington** » Thu May 13, 2004 11:15 pm

one new and one old drum

aha - so 1 new and 1 nearly new drum?
I had visions the 'old' one would be like my first Minor where they were hlaf the thickness of a new one and the corrosion was so bad that the surrounding flange was starting to dissapear.

Post by **Chris Morley** » Fri May 14, 2004 12:36 am

aha - so 1 new and 1 nearly new drum?

No, one is nearly two years old, the other is at least 5 years old (i.e. before I got the car). I've got a drum with a cracked flange and worn down inside by over 1mm which came with a s/hand hub & backplate I was given - definitely fit only for scrap!

Post by **Kevin** » Fri May 14, 2004 11:06 am

I don't think a missing rubber is an automatic failure.

A couple of years ago when I had a failure for a missing front bump stop, and when I asked why it was not advisory he said its an auto failure to have a suspension part missing, and when put like that I had to agree.
I think some cars get through because the testers are not aware of them especially if both are missing.

Post by **57traveller** » Fri May 14, 2004 11:53 am

I think he was wrong there Kevin and you were very unlucky, he maybe could have got you on "properly maintained" vehicle though. I've read somewhere (on the web), I'll try and find it, that it is not a failure for a missing bump stop - in the MOT testing manual. However there are other bits in the same section refering to suspension travel and clearances between suspension and bodywork etc.

Post by **57traveller** » Fri May 14, 2004 11:58 am

Found it Kevin. Go to http://www.motuk.co.uk/search.htm and enter "bump stop" in the box. Then open paragraph 1.

Post by **Kevin** » Fri May 14, 2004 12:51 pm

Thanks 57 I will remember that for the future but as the garage is quite classic car user friendly I assumed he was correct, and as the free retest consisted of just checking I had fitted a new one I was quite happy, especially as if he finds headlamp alignment or something small is out its re-set for free.

Post by **57traveller** » Fri May 14, 2004 4:44 pm

Even if he was correct Kevin (possibly not), it's worth using someone you can trust and does the odd little thing eg. aligning headlights for no extra charge. Until moving from Liverpool I always used the same place and got to know them quite well. I've mentioned elsewhere that one of the testers used to work on Minors and other BMC cars in his younger days. He knew that if something minor (no pun intended) was not quite right, say a bump stop missing, I would sort it out a.s.a.p. and he would not make a big thing out of it.
Many years ago I used one of the tyre fitting places for an MOT, they insisted I went away and came back in an hour. The car failed on too low headlights, I was shown on their equipment but I'm convinced they had adjusted them low to con another £7 out of me to adjust them. I never went back -even for tyres. Subsequently I heard of someone whose car failed, at the same establishment, (yes they renew shock absorbers) with a front leaking shock absorber. I'm convinced they had sprayed it with WD40 or similar to make it look wet. It was apparently perfectly dry the previous day when the person had checked round the car.
Rant over!