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In for a possible solution to my own similar problems with the X1/9 brakes (same sort of long travel soft brake feeling).
What pads do you have? I've been told the greenstuff ones I have aren't amazing for having a firm pedal, but not tried an alternative.
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Jul 26, 2021 10:34:47 GMT
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Brakes can be annoying if there's air stuck somewhere, which sounds like it could be the cause of your issues. Are you pressure/vacuum bleeding (Gunson Eezibleed or similar) or just manually bleeding?
Apologies if I've missed it but do you have a line lock or load sensing valve in the rear brake circuit that could be stopping all the air coming out?
Are the Mondeo calipers mounted so that the bleed nipples are at the highest point on the caliper?
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Living vicariously through other people's projects!
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Jul 26, 2021 18:16:28 GMT
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In for a possible solution to my own similar problems with the X1/9 brakes (same sort of long travel soft brake feeling). What pads do you have? I've been told the greenstuff ones I have aren't amazing for having a firm pedal, but not tried an alternative. Fronts are EBC blue stuff that haven’t been bedded in yet. When I did take the car out, with them fitted, the brakes are so poor I didn’t think it was that safe to go any further. The rears are a standard mintex pad, they have been on there for a couple of years. they might be fine once being driven, I know with my bike the brakes feel spongy has, well a sponge, when not moving. But when you’re out riding yeah quite good so maybe the colder the same. It’s so long since I’ve driven the car properly I can’t member what the brakes were like when I first fitted and everything worked fine.
Saying that the don’t feel like I should do. |
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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Jul 26, 2021 18:32:48 GMT
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Brakes can be annoying if there's air stuck somewhere, which sounds like it could be the cause of your issues. Are you pressure/vacuum bleeding (Gunson Eezibleed or similar) or just manually bleeding? Apologies if I've missed it but do you have a line lock or load sensing valve in the rear brake circuit that could be stopping all the air coming out? Are the Mondeo calipers mounted so that the bleed nipples are at the highest point on the caliper? I don’t like pressure bleeding as I’ve seen too many reservoirs go bang, and coat the engine bay and surrounding area with brake fluid. I was using a vacuum bleeder and a electric pump. The same things I’ve used for last few years with on the issues on the car, in fact on many cars. But these didn’t seem to work properly on the Stag this time, so I was just using the normal way of bleeding. Also I just let it flow through the bleed nipple and it seems to flow nicely taking any air out with it. The bleed nipples are at highest point as it would be on the Ford. I did have a line lock but removed it as I thought this could be the issue, but there’s no other bit apart from the line splitter/divider which has the brake light switch. I know in the past I’ve had a system that seems to be completely bleed with no air at all coming out but still being slightly spongy. Then after a couple of days of driving re-done them and yeah a lot of air has been trapped somewhere. Otherwise I’m at bit of a loss because it’s got new calipers almost all the lines have been changed. I took the time doing them to make sure all the ends with flaired properly. There’s been 4 different master cylinders fitted, each time going bigger bore. The flexi hoses are braided, the only bits I’ve not done is the lines from the splitter to the flexi hoses. |
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Last Edit: Jul 26, 2021 21:59:03 GMT by Bullstarz
“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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Jul 26, 2021 18:45:12 GMT
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Always used a pressure bleeder, never had a single reservoir go bang. Although unusually i read the instructions first and only use 20psi max. I use a Sealey (pump to pressurise) one these days and its brilliantly usable as i don't have a garage and electric supply. Used it on my Boxster which has inner and outer bleed nipples on all four calipers, complete fluid change and strong pedal in about an hour and a half including jacking and wheel removal-refitting.
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Last Edit: Jul 26, 2021 18:47:25 GMT by duggers
Needs a bigger hammer mate.......
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Jul 26, 2021 19:01:20 GMT
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Points to remember about master cylinder sizes.
Bigger bore = more fluid movement but at less pressure and pedal travel
smaller bore = less fluid movement but at far higher pressure and more pedal travel.
Higher pressure = better brakes.
Master cylinders MUST be matched to the slave cylinder volumes, if they are not matched correctly then you will never have good brakes.
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Jul 26, 2021 21:42:34 GMT
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Points to remember about master cylinder sizes. Bigger bore = more fluid movement but at less pressure and pedal travel smaller bore = less fluid movement but at far higher pressure and more pedal travel. Higher pressure = better brakes. Master cylinders MUST be matched to the slave cylinder volumes, if they are not matched correctly then you will never have good brakes I understand how they work or how to supposed to, and the physics behind it. And this is my issue because what I know should happen, isn’t happening. But one of the main reasons for upping the rear master cylinder was when I did a Google search for the rear calipers. And the master cylinder used on the original car was 25.4 mm, equivalent to 1 inch. My idea was to fit 1 inch cylinder and everything should be fine and dandy. As the brakes would have the correct MC for each pair of calipers. I must admit I was expecting an almost rockhard pedal from the start. But nothing is how I thought it would be and is pretty much totally the opposite, of the physics, reality and what blackpopracing has said. And I know this should be true. Once again I’ve left the brake pedal depressed ( just like me now) overnight, well until I get back from work tomorrow. With the idea this should show any slight weeps or leaks, and it may also let any trapped air make it way out up to the MC. Then up to the res. It also might, sort of, reset the brake pistons as this does with my bike after I’ve change the pads. |
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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Jul 26, 2021 21:52:50 GMT
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Always used a pressure bleeder, never had a single reservoir go bang. Although unusually i read the instructions first and only use 20psi max. I use a Sealey (pump to pressurise) one these days and its brilliantly usable as i don't have a garage and electric supply. Used it on my Boxster which has inner and outer bleed nipples on all four calipers, complete fluid change and strong pedal in about an hour and a half including jacking and wheel removal-refitting.
I’ve not had one go myself, just seen the after effects. Normally down to user error but there’s one make think it’s VW that can’t take any pressure. The one we had at work did take about 18 Lt of fluid and was connected to the air lines. Which is a formula for things to go wrong, especially when the last person was using a rattle gun. Hopefully it is some random bubble of air trapped away somewhere and I’ve not just been a tawt. |
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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Jul 26, 2021 22:40:42 GMT
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You say the original used a 25.4 M/C, but was that a single 25.4 for both front & rear?
You can work it out mathmatically using the area of the rear pistons x movement of rear pistons, compared to area of M/C and movement of M/C to shift the volume of the rear pistons.
There is a sweet spot of travel for any M/C but I can't remember what it should be.
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Being from a modern car I'd expect it to be a tandem cylinder, so would be 25.4mm per bore which should map across well to the current bias bar twin setup.
The other factor to think about is the pedal ratio on the original setup. Hydraulics is just levers in another form, as I'm sure you know, but the leverage ratio of the pedal has a reasonable effect. If the Mondeo had a lower pedal ratio (so less leverage) compared to the Stag that would have the same effect as making the master bigger (having a firmer pedal).
Similarly, I expect the Mondeo would have been servo'd which would affect the pedal pressure setup if you don't have one on the Stag.
Tl;dr It might be that you need a different ratio than stock to get the pedal feeling right, although it could also be an air bubble throwing things off, so who knows!
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Jul 27, 2021 12:32:42 GMT
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Yes, the original Mondeo MC was a tandem so both front and rear has had the same 1” bore. I would think I’ve got higher pedal ratios than a standard car so that could be a factor yeah true. A servo I suppose that takes up the initial part the pedal where there is no pressure being built up as the depression is there to assist your breaking, so the brakes are different again. Who knows.
Have to see what is like when I finally will it out the garage but I’ve got all the bits I took off which will take a couple of days to get back on. But yeah I think there’s probably some air stuck somewhere and it might mean we’re just making a few more lines and re-believing them again, and again. I may bring the brake line splitter a bit closer and just try to equal longer length lines to the rear brakes.
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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Jul 27, 2021 18:57:20 GMT
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Pedal ration for non servo should be 6:1 or 7:1 ideally.
Ratio for servo is often around 4:1.
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Jul 27, 2021 20:35:23 GMT
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I had a similar issue years ago on an IOW frogeye, after 100 miles or so the brakes got much better and we're fine afterwards.
I used gallons and gallons of fluid, I bled it manually, with a pressure bleeder, with callipers upside down, on their side, rear brakes adjusted up so they were locked, it was a total nightmare.
Could it just be that the pads need to bed in?
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Pedal ration for non servo should be 6:1 or 7:1 ideally. Ratio for servo is often around 4:1. True, although having measured a few setups it seems to vary wildly. For instance my Spitfire has a 3.67:1 ratio and my X1/9 has 4.8:1, despite both being manual brakes! Not measured the Stag/2000 setup yet, although it's not too tricky. If I've got some time tonight I'll give it a go (it's basically just measuring the length from the pedal to the pivot, and pivot to the pushrod, with a small correction for the angle the pushrod goes if it's not directly perpendicular to the pedal). Not sure how much it would help without the Mondeo one, but might help point you in one direction or other. |
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Jul 28, 2021 16:53:09 GMT
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Looking at the manufacture spec, OBP Pro-Race V2 Top Mounted Cockpit Fit 3 Pedal System, they say the ratio is 5.45:1. But that is the newer version, I’m sure mine was a maximum of 6:1 ratio if you have the foot pad mounted the lowest possible place.
As for the pads need bedding in, the chance would fine thing. I know the fronts will take 100-150 miles, the short distance they have done you can see the bedding in compound is cleaning the surface.
Leaving the brake pedal depressed over night made a slight difference on Sunday-Monday. Noticed one slight weep and that was the union top of the master cylinder so that was nipped up. The pedal did seem firmer and had less travel until it felt firm. Then Monday I decided o the same thing and keep the pedal pressed in overnight. This was done by using a few 1/2 inch drive extensions pushed against the pedal by hand as far/hard as I could and then blocks of wood/metal to packet out against the seat. I found that I couldn’t use everything and the pedal distance had decreased by 10mm.
On Tuesday checked again it seems that firmer once again with less travel. So it seemed like leave it depressed overnight was having some effect, this time for the good. Tuesday I tried the same again but this time I can only use a 10mm spacer against the seat.
Today was better still with less travel and firmer. However it’s still not acting how I thought it would. I Have to use a mirror and lamp in the foot well to see what the bias bar is doing. And looking at it as you press the footpedal, the front moves first closely followed by the rear. When you feel the pedal go firm the bias bar is still cocked, so that will need to be adjusted. When you continue to press the pedal the front only moves slightly more but the rear MC compress a lot more. Not as much as it did but still more than I thought Iit would/should.
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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homersimpson has a point in that it could be the pads if they're not bedded in. A fair few have bedding in compounds layered on the top which can be softer. Is there anything flexing at the rear? Or maybe a sticky piston that's not moving enough with the first, less firm press?
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Jul 29, 2021 10:15:49 GMT
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It still sounds like air in the rear pipes somewhere.
Compressing the pedal overnight makes the fluid absorb air so it points to that scenario. In your rear brake lines do you have a high point anywhere that air could be trapped in? - if so then a T peice with a bleed nipple in the T could sort it.
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Jul 29, 2021 17:16:54 GMT
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It still sounds like air in the rear pipes somewhere. Compressing the pedal overnight makes the fluid absorb air so it points to that scenario. In your rear brake lines do you have a high point anywhere that air could be trapped in? - if so then a T peice with a bleed nipple in the T could sort it. Where the “T” is I suppose is one of the highest points but still a lower than the master cylinder. This was the next thing I was going to do, Move the “T” closer to the handbrake and the have two equal length lines running straight to the Flexi hoses. That will probably be the next thing, I did look at going braided from the “T” all the way to the calipers but it possibly not worth the cost, as just the fittings work out £50. |
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“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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Jul 29, 2021 19:04:56 GMT
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Try taking the rear calipers off and raising them up while bleeding as high as possible, see if that helps. Vacuum bleeder is really good for removing air sucky thing |
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Well reducing the size of the clutch master cylinder sort of worked but didn’t. I got the car back together and running and tried the clutch. With a pedal full of depressed it just started to disengage, but not fully. So I am going to have to put back in the 0.75 master cylinder. Great
With the rears brakes I’m going to replace the bits that I’ve not replaced, it must be air trapped in the “T” or is not an air tight seal.
The cooling system has been done hopefully this time it will be leak free. It was running at fast tick over for a while and the temp went up nice and slow. The EWP is now set to run at 8v until it reaches 60 degrees then rise to battery voltage at 86 degrees. It runs on for 3 second off for 6 until 50 degrees then on for 6 second and off for 4 until 75 degrees when it just on. I’ll see how that works may need re-jigging later. Might even have to fit the thermostat in the top hose if it take too long to reach temp.
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Last Edit: Aug 2, 2021 19:00:26 GMT by Bullstarz
“It Doesn’t Feel Pity, Or Remorse, Or Fear, And It Absolutely Will Not Stop, Ever, Until You Are Dead!”
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