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Oooer, I'm liking the simplicity of Rogers LSV solution here.
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Excessive brake pedal travel
- Thread starter Bat21
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Probably should have said the 'topic' is subjective, it always raises an opinion of which each of us is entirely entitled to.
Where I struggle to deal with issues as important as brakes it does seem I am perhaps a little OTT in my thoughts for example, you state it is difficult to get your brakes to lock up, on one hand that is good, sudden locking can be dangerous and contribute to a loss of steering and overall braking distance, and on the other hand (IMO) it is not so good, you want brakes to respond as you press the pedal with a consistent action. The simple act of bolting on larger diameter wheels and tyres will immediately reduce your braking power for a given pedal pressure, so again this leaves the owner to draw his own conclusions, whether good or bad.
regards
Dave
Where I struggle to deal with issues as important as brakes it does seem I am perhaps a little OTT in my thoughts for example, you state it is difficult to get your brakes to lock up, on one hand that is good, sudden locking can be dangerous and contribute to a loss of steering and overall braking distance, and on the other hand (IMO) it is not so good, you want brakes to respond as you press the pedal with a consistent action. The simple act of bolting on larger diameter wheels and tyres will immediately reduce your braking power for a given pedal pressure, so again this leaves the owner to draw his own conclusions, whether good or bad.
regards
Dave
Hear what you're saying Dave, to clarify, I struggle to get them to lock because the truck has come to a halt by then. They really are the best brakes I have had on a Cruiser. I can't leave stuff on the seats anymore as everything ends up in the footwell.
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Strap the wife IN next time.
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Just a quick follow up on this one.
I ordered a master cylinder from RoughTrax and asked them if they would exchange the leaking LSV, at which point Barry then came to the phone, I have spoke to him before and he is a very knowledgeable chap. He said he has never known one of their LSV's to be faulty but did ask me to check the large (30mm I think) 'nut' that screws into the bottom as it may be that it wasn't fully tightened on assembly.
The master cylinder arrived earlier this week so today I set about tacking the job. The LSV 'nut' did in fact tighten up a little so I was hopeful that is all it was. I fitted the MC and bled all the wheels and the LSV just to make sure.
I now have a nice firm pedal that no longer creeps if my foot is left on it.
I had the old LSV (that I still had from when I fitted the replacement a few months ago) modified so it is nothing more than a 3-way link now, I will keep this as an emergency get me home in my spares kit that I carry in the truck.
I ordered a master cylinder from RoughTrax and asked them if they would exchange the leaking LSV, at which point Barry then came to the phone, I have spoke to him before and he is a very knowledgeable chap. He said he has never known one of their LSV's to be faulty but did ask me to check the large (30mm I think) 'nut' that screws into the bottom as it may be that it wasn't fully tightened on assembly.
The master cylinder arrived earlier this week so today I set about tacking the job. The LSV 'nut' did in fact tighten up a little so I was hopeful that is all it was. I fitted the MC and bled all the wheels and the LSV just to make sure.
I now have a nice firm pedal that no longer creeps if my foot is left on it.
I had the old LSV (that I still had from when I fitted the replacement a few months ago) modified so it is nothing more than a 3-way link now, I will keep this as an emergency get me home in my spares kit that I carry in the truck.
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Mint. Did you get the aisin mc?
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Glad you got it sorted.
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Well.... went to the 80 this weekend to take her out for a run and the brake pedal went straight to the floor again 
After a couple of pumps it is fine but once released and left for a few seconds, there's no pedal again
There is clearly air in the system somewhere, but it is odd that the pedal was fine after fitting the new master cyl and bleeding the system.
How can air be 'reintroduced' into a sealed system
Thought of getting one of these and giving the system another bleed, anyone else used one?
After a couple of pumps it is fine but once released and left for a few seconds, there's no pedal again
There is clearly air in the system somewhere, but it is odd that the pedal was fine after fitting the new master cyl and bleeding the system.
How can air be 'reintroduced' into a sealed system
Thought of getting one of these and giving the system another bleed, anyone else used one?
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Sounds like a new faulty master cylinder. One of 2 things can happen:-
1. The cylinder seals leak and no pressure builds up as you press the pedal. You may be able to diagnose this by leaving it until you think it will fail and then stamp on the brake pedal. Sometimes this forces the seals against the cylinder wall and they work, but just under that condition.
2. The cylinder draws air into the system. When you take your foot off the pedal the piston sucks air past the seals instead of fluid from the reservoir.
I can't see how air can get in other than through the master cylinder. Once in there of course it can only be bled out. It will be useful to see if you have air when you bleed the brakes.
It's as if something is pressing the pistons back up into the caliper/s ? You don't have a loose front or rear wheel that is settling when the car is parked and tilting a disc/s ?
Have you had any trouble at all in the past with your brakes?
Did you do anything at all to the braking system just before this all kicked off?
1. The cylinder seals leak and no pressure builds up as you press the pedal. You may be able to diagnose this by leaving it until you think it will fail and then stamp on the brake pedal. Sometimes this forces the seals against the cylinder wall and they work, but just under that condition.
2. The cylinder draws air into the system. When you take your foot off the pedal the piston sucks air past the seals instead of fluid from the reservoir.
I can't see how air can get in other than through the master cylinder. Once in there of course it can only be bled out. It will be useful to see if you have air when you bleed the brakes.
It's as if something is pressing the pistons back up into the caliper/s ? You don't have a loose front or rear wheel that is settling when the car is parked and tilting a disc/s ?
Have you had any trouble at all in the past with your brakes?
Did you do anything at all to the braking system just before this all kicked off?
Towpack
Well-Known Member
I used something almost identical in conjunction with the Gunsons Easibleed, pressurised brake/clutch bleeding tool. I flushed the whole system and bled the MC, all 4 callipers and the rear PSV in 10-15 mins. Once it's setup it makes light work of the whole job. What I like about the Easibleed as opposed to the vacuum suck type bleeders is there's no need to keep topping up the reservoir during the operation.
I just can't see your problem being air in the system though. IME once air is in the system you have a spongy peddle all the time until it's bled, not spongy one minute and hard the next. Do you have ABS?
I just can't see your problem being air in the system though. IME once air is in the system you have a spongy peddle all the time until it's bled, not spongy one minute and hard the next. Do you have ABS?
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I had a similar but not so serious problem with a brand hew Land Rover I bought. It had an incurable spongy pedal. After 60,000 miles a wheel cylinder started leaking, as they do, and I stripped it. Somebody had fitted 1 seal to one side of the piston and 2 to the other side !! The extra seal, not being flat rubber, slowly pushed some fluid back to the reservoir after resting a few minutes.
It just makes me think you might have something mechanical happening at the wheel end.
It just makes me think you might have something mechanical happening at the wheel end.
I have a low pedal at the moment, before Xmas as preventative maintenance I replaced everything except the ABS system module, LSV and hard lines. Despite repeated bleeding the pedal travels further than before started. When I get the time I will have another go but have spent a couple of weeks in the UK visiting friends and family, having returned work has now taken priority.
I have the Sealey bleeding system with the adaptor linked to earlier and have used it on dozens of cars and in general it is great however, it does have it's downside/s. The main problem is when trying to push fluid through vehicles with ABS, it takes quite a bit of pressure to get a decent flow, the ABS part of the system creates the restriction. The theory is fluid under pressure going in will push out all air, the reality is if there is air at the top of a pipe then the fluid can pass under the air and flow out of the nipple in the normal way, this leaves the air behind, the flow has to be quite fast to 'carry' the air bubble with it, hence when using the pedal you can give it a hard shove and the bleeding is more successful. The problem with the pressure bleeder is two fold. First, if you need to use the adaptor (LC 80 for example) then it tends to leak from the connection to the reservoir, tightening the wing nuts in an effort to stop the leak results in the adaptor distorting letting out more fluid. I made a reinforcing bar out of wood, this fits across the adaptor and gives it the rigidity it should have had designed into it in the first place. The second problem is ABS modulator valves can be damaged by high pressure bleeding, this means you are limited to the amount of pressure (and hence flow) you can apply, this WILL leave air in the system.
IMHO the pressure bleeder is great for changing fluid in an already working system, connect/pump/open nipple/close nipple move on, 15 minutes all done but, when new components are fitted pumping 'the old fashioned way' is best to get air out on our trusty (but old fashioned) steeds.
Regards
Dave
I have the Sealey bleeding system with the adaptor linked to earlier and have used it on dozens of cars and in general it is great however, it does have it's downside/s. The main problem is when trying to push fluid through vehicles with ABS, it takes quite a bit of pressure to get a decent flow, the ABS part of the system creates the restriction. The theory is fluid under pressure going in will push out all air, the reality is if there is air at the top of a pipe then the fluid can pass under the air and flow out of the nipple in the normal way, this leaves the air behind, the flow has to be quite fast to 'carry' the air bubble with it, hence when using the pedal you can give it a hard shove and the bleeding is more successful. The problem with the pressure bleeder is two fold. First, if you need to use the adaptor (LC 80 for example) then it tends to leak from the connection to the reservoir, tightening the wing nuts in an effort to stop the leak results in the adaptor distorting letting out more fluid. I made a reinforcing bar out of wood, this fits across the adaptor and gives it the rigidity it should have had designed into it in the first place. The second problem is ABS modulator valves can be damaged by high pressure bleeding, this means you are limited to the amount of pressure (and hence flow) you can apply, this WILL leave air in the system.
IMHO the pressure bleeder is great for changing fluid in an already working system, connect/pump/open nipple/close nipple move on, 15 minutes all done but, when new components are fitted pumping 'the old fashioned way' is best to get air out on our trusty (but old fashioned) steeds.
Regards
Dave
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I never had any trouble on any of the very varied types of car I've worked on since the late 50's using just the old fashioned system. I don't think Toyota have an SST for bleeding so you don't need one.
Towpack
Well-Known Member
The adaptor I used looks a bit more sturdy than the one in the link. Can't remember what make it was but I'm sure it wasn't made by Gunsons. Suffice to say I had no problem tightening it down enough to avoid leakage. I think I used around 20-25 psi and got a strong flow of fluid from the nipples. On first use I accidentally emptied the front brake part of the system completely and had no problems pushing new fluid through thereafter. It is what the Easibleed is designed for after all! Can't see how using one would damage the ABS unit though. The pressure it generates is nothing compared to that when the pedal is used. JMO
I only have heard of two ABS modules being allegedly damaged one was on a Volvo S40 IIRC, and the other a Peugeot or Citroen? Something to do with the modulator valves opening before the pressure was great enough to lock the wheels? Some systems have ABS as an addition i.e. they are boosted by an additional pump, some pump 'through' the module. I would add there are plenty of 'do not over pressure ABS systems' warning so there may be something in it? I agree Frank, I have used the old method for many years but newer vehicle simply cannot be bled in that manner.
regards
Dave
regards
Dave
Towpack
Well-Known Member
The ABS system on the 80 series is obviously a very old design now and a bit more 'belt and braces' than modern setups. My road bike has ABS with a built in pump and a shed load of electronics. I bled it end to end recently but used the manual method of pumping the levers, mainly because I didn't have an adaptor to fit but also because it's obviously far easier than a car as you can reach the levers and the nipples at the same time! Couldn't see any warnings about pressure bleeding in the FSM though. Aren't the ABS systems on some modern vehicles also linked into the TC systems?
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Thanks for the repliers folks.
Mine is a simple 1992 none ABS model so it wont be an ABS related issue.
I popped up to Demon Tweeks today and picked up a Sealey Bleeding system and an adaptor to fit the master cyl.
Brakes bled once again, although I have to say not much air came out. Pedal now back to normal and brakes appear to be working fine.
I will leave it a few days and see if the mysterious lack of pedal returns.
Mine is a simple 1992 none ABS model so it wont be an ABS related issue.
I popped up to Demon Tweeks today and picked up a Sealey Bleeding system and an adaptor to fit the master cyl.
Brakes bled once again, although I have to say not much air came out. Pedal now back to normal and brakes appear to be working fine.
I will leave it a few days and see if the mysterious lack of pedal returns.
I know zero about motorbikes...well except that as a passenger on a Hyabusa (is that spelt right?) I nearly needed new underpants after a 'quick run a around the block'!!
And yes the ABS sensors are used to detect wheel slip when the brake pedal is not being pressed, I mentioned the Land Rover TD5 recently and the system is ABS brakes and TC. I have a fair amount of experience with these systems and the pressure bleeder will not work. and neither does the manual pedal push method. The TD5 TC use is quite crude in this application, the amount of revolutions the spinning wheel has to reach before the brakes are applied is quite high, this results in quite a 'lurchy' progress across poor surfaces. The later versions have a more gentle application of wheel braking which results in the valves not being subjected to such high and sudden pressures.
The brake callipers use laptop/software to be bled, kneel by wheel spanner in hand, press button on laptop and open the nipple, software decides when the brakes are bled, it is only when you have bled the ABS module with a laptop from the TD5 drivers seat, retracted brake pistons on Audi's with a computer to get the pads in, how accurate your 'very old design' comment is.
regards
Dave
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