Calling All Brake Gurus

[Bibs]

I still do not have the information to command the ABS computer to do a bleed procedure. However, if I could borrow a Tech 1 with the ABS cardridge, I could try to record the datastream and figure out the protocol. Then can add the bleed function to Espritmon.

I'm working on this for you

[Jonathan]

See post #173 just use your right foot.

[G_Reaper]

Hi

Everyone I am now faced with the fact my ABS pressure switch is U/S. I have tried cleaning it but failed.

I was wondering does anyone have a pressure switch lying about that they have replaced without trying to clean it first? If so would you be prepared to sell it so I can try cleaning it.

I know its a long shot but what else can I do??

Does anyone know if the twin switch system someone was developing ever got off the ground?

Any help would be greatly appreciated.

I am going to let a local engineering company dismantle my switch to see if it is possible to offer a reconditioning service or a replacement can be sourced.

Regards Mike

[Bibs]

http://www.thelotusf...42&#entry302542

Fancy lending me your car? Lotus need one to test their alternative switch which is soon to be delivered.

[ramjet]

The twin switch system is a functioning unit. Steve Taylor of the Elan Factory in Melbourne has built it, got the engineering paperwork sorted etc. I will call him tomorrow and talk to him and then post back here what I find out.

[G_Reaper]

Hi Bibs

I would lend you my car but, I am such a long way from the factory, near Newcastle, + I am just in the proccess of recommisioning after a 3 year lay up.

Regards Mike

Hi

Just another thought if LOTUS send me the switch I will try it out for them. I would obviously do this in an analytical manner.

Cheers Mike

[Bibs]

Nice try! Lotus are investing a significant amount of time and money into this. Unless you're a fairly significant and experienced global car manufacturer I doubt you'll be able to replicate the required testing, it's a touch more involved than sticking it in and seeing if it works.

[t70]

I should check again with the pressure switch thing.. I haven't been a very good forum user of late.. and have kind of stopped posting a fair amount. Perhaps after our fiscal month is over, I can check it out and see what I can find on the market over here.. Pretty sure it was from a Pontiac Grand-Am (correct me if I'm wrong) and that there was stock in the US. I gave up on the idea because the pressure switch solved my abs light problem. However, it would appear that now I need a new nitrogen bulb instead LOL!

[G_Reaper]

Hi Bibs

If Lotus want to ship my car back to the factory do the re-commision (sort out all faults)especially the ABS switch. They could carry out the testing they require and return it in undamaged pristine condition I would go for that. The car is an S4s and has only covered 30,000 miles.

A long shot but worth a try. lol

Cheers Mike

[G_Reaper]

Hi Bibs

Any idea of the time scale for the new switch to be available?

Ramjet Have you any news on the twin switch system?

Regards Mike

[Bibs]

A month perhaps?

[ramjet]

Ok everyone.

I spoke to Steve Taylor today. He thanked me as people from the esprit community have already contacted him and bought the setup. As no-one here mentioned anything, possibly it was lurkers that own an esprit, but have not joined.

Anyhow, the cost of the setup is $400 AUD. Which converts to about 232 GBP or 336 USD.

This is the high pressure switch, the low pressure switch, the piping and fixings to go in the brake booster and the wiring loom to connect to the car. Unfortunately, Steve can not find a female connector that matches the current brake switch connector. His setup at the moment is soldered into the car loom after cutting the existing plug off. Steve can supply an alternative 3 wire connector that you could solder in which would be neater AFAIC.

The switches however, are not off the shelf items. To switch correctly Steve had to source outside the auto industry. The switches have to be calibrated to the correct pressures prior to assembly and shipping. The piping also is all double sealed to prevent any sort of failure.

Steve has full engineering certification for the setup as a valid solution for our problem on this ABS system.

Now this is the good bit. If we organise a group buy (minimum of only 6), Steve has said he will discount each unit as he will save money on the calibrating which is done by another company.

The phone number for Steve in Melbourne at The Elan Factory is +61 03 97611903.

My switch is ok at the moment though it is going soft on the high pressure side. So if the forum does not have enough members to make 6 now, I'll chuck my name on to make up numbers.

Michael.

[G_Reaper]

Hi

I tried cleaning my ABS presure switch. Can anyone supply photos of their switch and a description of what it should and should not do.

The small hole in the face of my switch was closed by a internal metal part. When this part was pushed gently with a paper clip it moved reluctantly it then stuck leaving the switch hole open. it took some brake cleaner and a very firm tap of the swith on a block of wood to get th hole to be recovered again. I tried this a number of times but this seemed to not change the quite stiff internals of the switch. Is this normal? What moving parts does the switch consist of? I refitted the switch but the ABS light is still flashing. Any other help would be appreciated before spend alot of money.

Bibs have you any details of the potential cost of the Lotus switch?

Where would I find the accumulator on a Jag XJ6.

Cheers Mike

[G_Reaper]

Is anyone up for a group buy of Steve's presure switch from the Elan Factory Melborne?

I am but I would like to order sooner rather than later.

Cheers Mike

[CarlC]

Hi Mike,

Your doing the right thing with your pressure switch. I have all the pictures sorted and plan to complete the first draft of the guide for fixing the ABS pressure switch this week. I WD40 sprayed inside, tapped (banged) out the pin then with compressed air,got the centre pin to go back in. Repeated this about 10 times, soaked then to be sure soaked the centre section in WD40 over night, cleaned it out with air, so the pin wasn't junked up inside. Not that you can see in there. This did resolve my ABS warning light issue.

I was hopeing to include a nice piece about full brake bleed to, based on Jon's huge efforts with the brake system after completing the process on my car this weekend. Unfortunatley, although my ABS pressure switch seems to be fixed, my brakes still have no servo assistance. They feel great at very low speed, but put under any pressure (basic road use) and they drop away to basically no assisatnce.

This is with a full bleed of Delco system along with new fluid flushed right through all calipers. I went overboard to ensure the problem was fixed once and for all. But sadly no luck, No ABS warning light, but also no brake assistance either.

[MartinL]

Same problem, followed same procedure, no assistance, conclusion S4 brakes are shit, got to replace the whole system to be sure!

[CarlC]

Jon suggested that one area could be the seals in the master brake assembly, which would make sense and fit with the symptoms. However, Lotus Service Notes seems to indicate that the whole unit is not serviceable and requires a full replacement only. Anyone got any take on this ?

The options for full replacement of the Brake servo system as I understand it are somewhat more limited due to the lack of machanical vacuum pump being available in our cars. An I cant believe the system was this bad when they origonally sold the cars. I'd also be concerned about difficulties with the insurance company's over a non factory fitted brake system. I cant see that going down to well.

So, with some encouraging words from John about the improvements hes found, I'm currently just about resigned to the fact that I may have to replace the master brake assembly and fairly large cost (£400 ish).

Any help or suggestions is greatly appreciated.

[Jonathan]

Few quickies....

....ok Im back

How long do your pumps run for after a full de-pressurise ? (should be about 30-40 seconds)

How many times can you apply 50% max pedal force before the pump runs (should be 3-4)

Push down on the pedal and hold for 2 minutes, does the pump ever run ? (shouldn't, meaning there is not leaks)

This should prove / disprove the pump, accumulator and any internal damage.

It's likely the unit is not servicable becuase it's pressed together and needs to be cut open or the seal kit does not exist.

If it were my car I would probably be looking at the twin master cylinder setup with no assistance (similar to the Elise) and get some time in on emergency braking and non-ABS braking to get used to it.

This is the setup I am going to use in place of the delco when it does finally go tits up on me (mines working OK now but I have no doubt it'll kop out sooner or later)

Also try disabling the ABS by yanking the fuses - mine runs non-ABS atm and it marginally better imo.

Lotus were after a car to do some tests on, 2 fine candidates ?

[CarlC]

Hi Jon,

The results before the full bleed were as follows, but i will retest tonight ...

How long do your pumps run for after a full de-pressurise ? (should be about 30-40 seconds) =

Took about 42 seconds - but i was counting in my head - Ill stop watch it tonight.

How many times can you apply 50% max pedal force before the pump runs (should be 3-4) =

yep, 3 times - then pump would fire.

Push down on the pedal and hold for 2 minutes, does the pump ever run ? (shouldn't, meaning there is not leaks) =

Not tried this but will do tonight and report back.

Cheers Jon

PS... The eagle has left the nest for Italy!

[MartinL]

Checked mine also,

Pump runs after 4 pushes;

pump runs 32sec. to refill after depressurising,

can hold pedal till leg aches and pump wont run, no leaks...........

whole system bled as per Jonathans procedure, all fluid replaced,

all calipers stripped, cleaned, checked for leaks and sticking pistons, new pads etc, car pulls up in a straight line,

JUST NO ASSISTANCE

AAAAAAAAARRRGHHHHHH

ABS disabled

So do I now pay 400+ for a new master cylinder or fit a Wilwood master with proportioning valve in line to rears with no servo and no abs. at approx £150

[Jonathan]

Very stronge...

The no-assistance thing is puzzling, if you push the pedal 4 times and get a pump run that means the system has used the internal boost (assist) function and drained fluid pressure from the accumulator. This helps prove the switch as well.

Clever argument would be "ahah ! but the switch is reading under pressure" fair comment but it would not take 32 secs to pressurise...if the pump ran for 10 secs you know the switch is working, but at a lower pressure.

If the brake pedal is pressed and there is no pump run then then internal seals to the boost chamber are also intact of you would get a slow internal leak from high pressure site to the reservoir.

Try disabling the ABS and see if you can lock the tyres up on braking from 40mph - jam that pedal in, I wanna see -3g decelleration !

If the car can lock the wheels I'd be suprised if the system isn't working - sounds more like there could be an issue with perhaps the fronts or the rears not digging in correctly - even though the pistons move there is no indication that they clamp down.....its the only suggestion I can come up with, to take them and get their clamp pressure tested - usually this is done on lockup tests (can the caliper lock the wheel) the fronts will likely lock way before the rears but you could test this very carefully by bleeding off the fronts - clearly you need at least 100 meters run off on a closed road to do this but it saves taking them off and putting them on a pressure meter.

Extreme but it could save a lot of time/effort.

[MartinL]

Jonathan.I have followed your brake bleed method and the manual and another method reccomended by a lotus mechanic, i am certain the system has no air in it but I still have what I consider a soft pedal, however the car has just passed its MOT with the tester commenting thaathe brakes work a lot better than they feel, I know they will never feel like a modern overservoed bm but they just dont inspire confidence. my over 40 elan +2 has far superior stopping power and that is no 100mph+ supercar, just dont know what to try next.

[CarlC]

Hi Martin,

Did you bleed the Inboard and outboard bleed nipples on the master cyclinder?

The outboard one is a huge pain to get to. I've left a bleed pipe attached incase I ever need to do it again. I couldnt believe the bright orange sh1t with bits in it that came out of the outboard side of the master cylinder. The Service notes advise that this is the last nipple to bleed. So following this, all the calipers and inboard side bled nice and clean but only the outboard side showed any sign of crap coming out. It took a good 200-300ml of fluid before it ran clean with no bits coming out.

[Jonathan]

I had similar pains with this - it took me ages to bleed it down but thats what it sounds like.

You need to do a test on the brakes clamping force as I said - mine on the GT3 (same brakes) were 227 KG front and 220 rear each - giving the car a total force of nearly 900kg of braking force.

Again, disable ABS and try a lockup test, if the brakes lock, there's nothing more they can do ! Its the tyre that stops the car.

Have you any swelling in the flexible lines ?

Lastly what pads are you using ? Are they glazed, are they bedded in correctly (some have a mm or so protective coat of rubbish) - are your disks new / old / worn ? Too much disk wear and the pads have to come out more causing them to rotate slighty on the caliper and not providing the best friction.

You can try bleeding the master cylinder, be careful though - when I wound mine back in they seemed to want to keep turning, I might have stopped just before sheering the threads on the aluminium body, then you would be in the shit !

[CarlC]

Hi Jon,

I wasn't brave enough to de-pressurise the accumulator again for the test, so I thought I'd try the 50% pedal hold test and number of presses before pump run.

How many times can you apply 50% max pedal force before the pump runs (should be 3-4) = Exactly ,3 presses first time, and 4 presses second time before pump run.

Push down on the pedal and hold for 2 minutes, does the pump ever run ? (shouldn't, meaning there is not leaks) = Er... Yes, Pump ran at 1:10 and 2:40. It also ran for a good 5 seconds.

This i guess this could help explain my syptoms of - good firm pedal feel at very slow speed braking. But on road use with much heavier pedal use the pedal at the start seems to give a firm feel but then drops away to what feels like no assistance.

I topped up the fluid to exactly the right level - so I'll go and check this to see if i have lost any.

Edited June 26, 2010 by CarlC