Advice on brake judder, might not be easy...

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phorbiuz
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Advice on brake judder, might not be easy...

#1 Post by phorbiuz » Sat May 06, 2017 8:24 am

Hello again everyone.

It's been quite some time since I've been on here, in fact a quick search suggests nearly 2.5 years, but I'd appreciate some advice on a braking problem.

Vehicle is a 1984 Ford Transit AutoSleeper pop top (featured in the owners vehicles section some time back). It's been sat for a while due to an intermittent and irritating brake problem I can't trace, but I'd like to get it back on the road for festivals this summer. Most of the time *but not always* when you brake you get a considerable judder/pulsing through the brake pedal. I think the fact that occasionally it doesn't do it is somehow important to finding the problem.

So far it's had the fluid flushed through, and up front new discs, new calipers, new pads. On the rear it's had new shoes, new hub seals, new cylinders, rear drums were skimmed (the engineering shop said they couldn't fault them in the first place so it was a very light skim), then rear drums were replaced with new old stock I found on the internet.

Nothing so far has worked and I'm all out of ideas. As it's not quite every time I press the pedal I can't believe it would be discs or drums, especially as they've all been replace to no avail.

Any suggestions please? It's getting to the stage I'd happily take it to a more professional garage but with no idea of where the issue is I don't like the idea of giving them a blank cheque.

Have a pic.

Image
1971 Ford Cortina 1.6L
1979 Ford Cortina 2.0GL
1984 Ford Capri 2.8i
1985 Ford Transit 100 AutoSleeper

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JPB
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Re: Advice on brake judder, might not be easy...

#2 Post by JPB » Sat May 06, 2017 11:08 am

Given the amount of part swapping you've already done, and having looked at all of the other suggestions you've had made in the forum that caters specifically for your van since 2014, the one thing I'm not seeing mentioned in other folks' [entirely logical] replies is the condition of the front springs and/or their shackle bushes. I've met this symptom before (on a MK1 with a gull Luton body) and in that case, because the front springs were sagging and all shackle bushes had been erroneously replaced with soft polybushes, there was insufficient castor and that was the cause of the juddering under braking. Get an alignment test done but make sure that it's carried out with a couple of people in the front seats, if the castor figure is too close to vertical or, in extreme cases forward of it, then that will give you judder under braking.
Tyres that are close to or beyond their permitted lifespan can also be a factor, but they'd be more likely to do this under all conditions and not just when braking.
JB I didn't go looking for the current fleet, they just sort of followed me home and now they won't leave without an extradition order from the Japanese government..
:|

phorbiuz
Posts: 33
Joined: Thu Jan 06, 2011 9:11 pm
Location: St Helens, Merseyside
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Re: Advice on brake judder, might not be easy...

#3 Post by phorbiuz » Tue May 09, 2017 2:38 pm

Thanks for the reply.

For some reason this site is blocked when I'm in work so I've had to wait until I'm home again to post this. I'll certainly give those areas a check next, something which has never been suggested yet. I quite like the other site you mention but after running out of any suggestions I thought maybe a more generic board might bring up something new.

Dave.
1971 Ford Cortina 1.6L
1979 Ford Cortina 2.0GL
1984 Ford Capri 2.8i
1985 Ford Transit 100 AutoSleeper

sandy1
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Joined: Fri Aug 25, 2017 4:36 am

Re: Advice on brake judder, might not be easy...

#4 Post by sandy1 » Fri Aug 25, 2017 9:12 am

Sorry it has taken me so long to reply to this problem of brake shudder. However have had a few problems trying to register as a contributor to this site.
Being a Ford the most likely cause of your brake shudder is the small screw on the shaft of your brake booster behind the master cylinder that tend to protrude out and cause the master cylinder to pulse thus cause brake shudder when applying the brakes and also sometimes causes the car to shudder while driving, The fix is a 10 minute job
1. Remove the master cylinder mounting bolts
2. Move the master cylinder off the brake booster (you should not have to undo the brake fluid lines as they tend to accept gentle movement)
3. Inside the middle of the booster is a steel shaft with a small bolt screwed into the end
4. Pull the shaft out slightly and grip it with a pair of pliers or multigrips
5. tighten the small bolt in 2 full turns
6. Reinstall master cylinder and test drive the car
Here in Australia I have had the problem with my 2005 Ford Fairlane but i believe it is common across many Ford products. Attached is a Youtube link that might help you visualise thr fix https://www.youtube.com/watch?v=GrFEzfDnzqM

Also check that your brake hoses to the slave cylinder have not been twisted as this can cause problems as the material inside tends to block the hoses intermittently

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JPB
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Re: Advice on brake judder, might not be easy...

#5 Post by JPB » Sat Aug 26, 2017 2:44 am

:? In case anyone else has confused these two entirely separate brake issues, ie the low pedal which does actually relate to the pedal travel just as some of the respondents to that clip have observed - and brake judder known to be curable in most cases by changing the front springs to rectify the kpi, or even by fitting the aftermarket wedges to the underside of the front axle where it fits on the spring saddles - please don't be tempted to attempt any procedure that effectively reduces the available travel unless you really want to be trying to adjust all of the excess off again once the (necessary) clearance has been taken up in order to address an issue that wasn't caused by that in the first place, usually at dead of night and miles from anything!

Adjusting the effective length of the m/c pushrod cannot cure brake judder but then the video doesn't claim that it can! That judder wouldn't be related at all in cases where the vehicle in question shares the Transit's front beam, kingpins and trap springs. The clip relates to long travel at the pedal and unless someone has had the phantom fecker-upper in about at it, then that factory set length MUST NOT be messed with.
JB I didn't go looking for the current fleet, they just sort of followed me home and now they won't leave without an extradition order from the Japanese government..
:|

sandy1
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Joined: Fri Aug 25, 2017 4:36 am

Re: Advice on brake judder, might not be easy...

#6 Post by sandy1 » Tue Aug 29, 2017 5:18 am

Hi John (JPB) In my case with the brake and steering shudder It occurred intermittently when I touched the brakes and also intermittently would vibrate like poor wheel balance while driving. If I hit the brakes hard the problem sometimes disappeared to reappear a little while later. I had owned this car for 5 years and it had never had this problem also no one had ever touched the master cylinder apart from regular brake fluid changes
I had it back to the local Ford service workshop and had front end checked and front discs and pads replaced and calipers serviced also at the rear end the bushes were replaced on the independent suspension control arms also the sway arm bushes the rest of the suspension and brakes were inspected and found within tolerance.Engine mounts checked with no problems. Then front and rear wheel alignments Also at this stage the tyres were replaced and the rims inspected Total cost $2800
I left with the car and a few days later the problem reoccurred. back to Ford they suggested the car may have a twisted frame after an previous accident but apart from that were totally useless
Discussion with a neighbour who turned out to be a mechanic for another Ford dealership, told me about the master cylinder rod adjustment screw coming out on many Ford Falcons and causing the brakes to apply very slightly in a pulsing action He said it sounded like my problem and as I had nothing to loose I did this adjustment. 2 years and 38000km later and the problems have not reoccurred. The only difference i felt was a very slight different feel in brake travel to what i had become accustomed to but this either settled down or I got used to it within a couple of hours. (reason for the screw altering position remains unknown as it was not loose to unscrew infact felt like screwing a bolt into rubber) but it fixed my problem with minimal effort
My reason for posting the youtube link was it was the closest video i could find that showed the method of getting to the spindle even though it was a slightly different problem
I understand that you know a lot more about the vehicle in question and the problems that particular vehicle has. However I read the original posts noticed the similarities to my previous problems and that none of the suggested fixes seemed to fix his problem so decided to offer my experiences as an easy no cost possible fix that could be reset to original settings if it did not correct the problem

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JPB
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Re: Advice on brake judder, might not be easy...

#7 Post by JPB » Tue Aug 29, 2017 9:20 am

My apologies for jumping so hard on this point, I make no excuses for my paranoia about the potential for disaster that exists where brake systems are concerned, :oops: but I see now where the idea of adjusting the m/c pushrod comes from, and it's good that this has worked for some of those who experienced a particular system fault, my concern is that adjusting the pushrod can mask the underlying cause of a mechanically induced judder, especially in a system with drum brakes at one or both ends, since usual practice in the production engineering of such things will allow the brakes to work throughout the entire range of the available adjustment on the shoes, but by introducing a change in the effective ratio of pedal travel to friction material movement can be sufficient to mean that, if the shoes were under adjusted and the pedal low to start with, then a situation could arise where the available travel at the pedal could be used up before the brake application had achieved enough effort to slow the vehicle, as - for example - a distorted drum would cause judder but this judder would be minimised if the shoes were prevented from achieving full contact under hard use of the brakes, hence my concern about the procedure.

I appreciate that such concern on my part assumes that not everyone keeps up the adjustment at their brake linings to allow for wear and also that, for those of us who have some working knowledge of the way in which hydraulics do their job, then the risk is minimal, but the current proliferation of advice videos on the internet is something of a curate's egg and, sadly, some of these videos display a tendency to assume that the viewer has perhaps more understanding than they actually do regarding the advice being provided.

:)
JB I didn't go looking for the current fleet, they just sort of followed me home and now they won't leave without an extradition order from the Japanese government..
:|

alabbasi
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Re: Advice on brake judder, might not be easy...

#8 Post by alabbasi » Tue Sep 05, 2017 3:25 am

Are you sure that the issue is in the brakes and not worn steering components? Your braking at certain speeds could create vibration at the wheel from worn pitman arms, tie rods, ball joints etc that may not show up while going down the road.

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JPB
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Re: Advice on brake judder, might not be easy...

#9 Post by JPB » Tue Sep 05, 2017 9:43 am

Absolutely, and Ford themselves solved this issue when they started fitting independent suspension in later vans. But even if the front springs have flattened a little, introducing more kpi and setting the castor correctly is a known cure for these symptoms in Transits and other vehicles with trap springs and a beam axle. Without sufficient kpi, then changing the drop arm and/or any other component around the steering box won't help.
Worn kingpins could cause the same problem, but for them to be slack enough to allow the vertical links to fall forward of their correct kpi, the MOT would have highlighted the wear, even though they won't fall apart in the way that a balljoint-based setup can.
JB I didn't go looking for the current fleet, they just sort of followed me home and now they won't leave without an extradition order from the Japanese government..
:|

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