13 replies to this topic

[Norris73]

A few months back I had a topic open for issues with the drum brakes on my Mini Clubman estate, after a classic specialist garage totally destroyed them.

 

I am now £700 lighter and have replaced the following - Master Cylinder and pipe work, Brake compensator valve, all flexis, Minispares drum to 7.5" disc conversion - swapped out bearings for gen Timken, new tie bars and bushes, both front tyres new, new lower arm bushes, new track rod ends, and about 2 gallons of brake fluid.

 

The car brakes much better than with drums all round, however it pulls to the left, this become wild when trying to do a controlled emergency stop (the wheel skids and locks up and feels like it is going in under the car!). I have stripped both front brake setups, confirming the caliper pistons all move freely. Calipers have been checked for tightness against the hub. I have jammed the brake pedal lightly with a piece of wood and both front wheels seem to require similar efforts to rotate, and when the brake pedal is jammed hard with a piece of wood the wheels both are impossible to turn. The rear wheels however dont seem to have much braking effort, I can turn these by hand with difficulty when the pedal is jammed down - adjusters, adjusted to one quarter turn back from wheel locked.

 

Any one got any advise?, at the moment Im approx. 100 hrs into this and haven’t been able to use the car since December. Im even contemplating handing the job over to the one and only garage I trust down the road, but they are £80 per hours now!

 

Thanks,

 

Olie

 

 

[hunterg30]

Have you got the same make of tyres on both sides this can cause problems if they are different

[unburntfuelinthemorning]

Might be worth seeing if a friendly MOT station will test the brakes in the rollers so you can see if it's an issue with the brakes.  If that checks out then it'll be suspension or tyres at fault.

[cal844]

I'd say the back brakes are ok, do the brakes lock with the handbrake on?

Have you had the suspension geometry checked and adjusted?

[Spider]

I doubt the issue is from the brakes but a component in the suspension or steering (or both) that's causing this.

 

Have a look at;-

 

     Suspension Rubbers

     Steering Rack and the Rod Ends - these are spring loaded and can be hard to check properly

     Steering Arms where they are bolted to the hubs - along with the bolts, they should have hollow dowels as well and they need to be TIGHT

     Ball Joints - the Lower ones in particular are Spring Loaded and can be hard to check

     Subframe Rubber Mounts - personally, I think these are a bad idea and I'd be swapping to solid mounts, but at the very least, be sure they are in good order

 

Also check for cracks in the body around the steering rack mounts

[richmondclassicsnorthwales]

Hi

 

Yes, as Moke mentions above, all possibilities, and also look at the front tie bar bushes, along with the lower fulcrum pin bushes

 

Knackered tie bar bushes can cause brake weave

[Norris73]

Thanks for the suggestions so far.

 

Its good to hear that the obvious culprit (the brakes) are not the only possible issue here.

 

The front tyres are odd (Kuhmo/Power Star on Drivers and Falken SN807 on passenger), however these have been on the front for 3 years and have not caused issues previously with the drum setup, I will try swapping a Falken SN807 from the back to the drivers front to rule this out though.

 

The tracking/geometry has always been a bit of a pain, I now only have two selected garages that I trust with my cars, 1 is a tyre fitter who’s tracking gauges only fit 12" + wheels (and despite our best efforts we can’t track the 10s accurately), the other garage doesn’t have tracking gauges. I have in the last couple of months centered the rack (a 6mm drill bit in the passenger side access to the steering rack (wheel was a quarter turn out). I then adjusted track rod ends (newly fitted ones) and used two axle stands and a plumb line to get the tracking as close as possible, no wear has been evident on the tyres in the last 100 miles covered, and the car tracks straight and true (when the brakes aren’t applied!!)

 

I have done major works to the suspension over the past three years the following has been renewed - front doughnuts, front knuckle joints, lower arm bushes, track rod ends, tie rods and bushes

Will double check the tie bar bushes and tightness of tie bar at both ends to rule these out, (I have had new tie bar bushes perish in under 12 months before), the ones currently fitted at the minispares poly/rubber kit with the purple poly bush fitted on the outside and the rubber bush on the inside).

Ball joints all new when building up the new hubs (shimmed as I have done in the past without issue, springs installed in bottom joints).

Subframe mounts im certain were changed by previous owner perhaps 7 - 8 years ago will have to check.

The steering rack is tired! its the original, however slipping the boots off just before MOT time and packing with fresh LM2 grease keeps the mot man happy and it has never come up as an issue, however I know there is slight play in there.

 

Going to ring my MOT garage up tomorrow and get it booked in for a session with the brake tester, just wont to know the brakes are all working correctly. I think the effort on the rear brakes is confusing, as previously the master cylinder was connected up incorrectly with the old drums all round setup, so the front circuit was operating the rears and vice versa. This has now been resolved with a new pipe kit and master cylinder. Rear brakes apply, but can be turned by hand. Handbrake locks up rear wheels much better than foot brake - although I guess this may be by design.

 

Thanks for all the tips.

 

Will keep you all posted.

 

Olie

Edited by Norris73, 16 June 2019 - 08:51 PM.

[Spider]

From your description here, I'd say it's the steering rack. You don't need much play at all in them for issues - like what you have - to surface.

 

With better Brakes, it only further highlights issues like these.

[Homersimpson]

Years ago I had a similar problem with my dad's ford Sierra, I took it to a friend's garage and he put it on his brake test rollers and you could clearly see one of the wheels moving back when he braked on the rollers.

Turns out it was knackered compliance bushes. It would be worth checking all the suspension bushes and rack as mentioned above.

[cal844]

I had an issue with my Clubman Estate, it was all over the road, worse on the brakes... I just adapted to drive the car as best I could... even though I wouldn't recommend it!!

As Chris says the steering rack had play on the UJs at the rack end. We actually Replaced the steering rack twice in six weeks due to the reconditioned one not being done properly... 2 years later the rack is now tight or heavy to turn, it feels like a 4x4 with reduced power steering!

So yes I'd check the rack and also double check everything else. Grease all the nipples including the top arms as it did make a difference on my car.


Hope this is of some help

[unburntfuelinthemorning]

Try swopping the tyres first though before you do anything else as you have differing compounds on the front. 

 

Your way of setting the wheel alignment by direct measuring can be quite accurate.

 

I've used one of these https://www.demon-tw...gauge-lon79620/ for years and have never had excessive tyre wear from tracking problems.

[Norris73]

Update!!

 

Just back from my friendly MOT station, they squeezed me in this afternoon. Brakes are perfect, from what I could see next to no imbalance on the fronts and perhaps 5% on the rears, would be an MOT pass without issue. I had a look at the front wheels and could see no obvious movement laterally during the brake test.

 

I may have just been feeling excited because of the success on the rollers, but the brakes to me felt better with less pull on the way home.

 

My next steps are to fit a Falken SN807 tyre to the front drivers side to match the front tyres up, then tie bar bushes and tightness of fixings, lower arm in nut tightness etc. Going on from there subframe bushes. After speaking to the MOT tester (who has had minis, most recently a 1275GT), the steering rack would be the last port of call because of the difficulty of the job.

 

Will be using the car at the end of the week so we will see how we go!

 

Thanks for all the tips,

 

Will keep you posted.

 

Olie

 

ps. unburntfuelinthemorning - many thanks for the link to the tracking gauges, these look far superior to any of the plastic tut that I have seen, will looking into purchasing this as a better option than bits of string!

Edited by Norris73, 17 June 2019 - 05:04 PM.

[unburntfuelinthemorning]

Here's another option too.  I haven't used one myself but others say it's very accurate:  http://www.trackace.co.uk/

[unburntfuelinthemorning]

I'd recommend one of these as well as a cost effective way of checking camber and castor:

 

https://www.merlinmo...er-gauge-adaccg

 

I ended up fitting adjustable tie-bars to even up the castor on mine.