Can I adjust servo-master cylinder gap without special tool?
Discussion
Interesting, this isn't a usual adjustment? Here's a page from the factory manual showing what's needed:
http://s17.postimg.org/n1x7103lb/Capture.jpg
http://s17.postimg.org/n1x7103lb/Capture.jpg
Sorry I didn't give details. It's a Suzuki Vitara, 1995.
Basically I've bled and bled the brakes and they don't bite quickly enough, ie the pedal goes quite far down before it feels firm. But more concerning is that when the car has been left for 5 or more minutes then the pedal takes 80mm before its firm on the first go, then 70mm, then 60mm on the third brake pedal press. After a few depresses then it takes 40mm (which I consider a reasonable length stroke).
This all happened after an overhaul. During the overhaul the calipers and flexible hoses were replaced. In the mean time the master cylinder had been drained (to stop fluid dripping out while the hoses and calipers were off).
Before the overhaul the brakes still took a long stroke before the pedal was firm, but I can't remember if it took a few pedal presses for the stroke to decrease. The car had so many rattles and problems before the overhaul that I had bigger things to think about!
I've got a spare master cylinder from a low mileage 1997 Vitara which I want to fit. But I don't have the special tool that the factory manual says is needed to set the gap.
The manual says to bleed the master cylinder first if it's been disturbed. I did this, but maybe not enough as I had my girlfriend helping me by pumping the pedal and she was getting very moany and bored in the cold garage so I slightly rushed the procedure. But the master cylinder bleeding procedure just says to pump the pedal while using your finger on the master cylinder output holes as a valve so that air does not get sucked in. It seems as though this is just to speed up the overall bleeding process rather than to do something that regular bleeding at the nipples wouldn't achieve.
I've also got a space servo, so I will see if the gap can be set before I do it for real on the car. I suspect that trial and error can be used to set this gap. Just need to pick up the servo from where it's stored in the warehouse at my workplace.
Basically I've bled and bled the brakes and they don't bite quickly enough, ie the pedal goes quite far down before it feels firm. But more concerning is that when the car has been left for 5 or more minutes then the pedal takes 80mm before its firm on the first go, then 70mm, then 60mm on the third brake pedal press. After a few depresses then it takes 40mm (which I consider a reasonable length stroke).
This all happened after an overhaul. During the overhaul the calipers and flexible hoses were replaced. In the mean time the master cylinder had been drained (to stop fluid dripping out while the hoses and calipers were off).
Before the overhaul the brakes still took a long stroke before the pedal was firm, but I can't remember if it took a few pedal presses for the stroke to decrease. The car had so many rattles and problems before the overhaul that I had bigger things to think about!
I've got a spare master cylinder from a low mileage 1997 Vitara which I want to fit. But I don't have the special tool that the factory manual says is needed to set the gap.
The manual says to bleed the master cylinder first if it's been disturbed. I did this, but maybe not enough as I had my girlfriend helping me by pumping the pedal and she was getting very moany and bored in the cold garage so I slightly rushed the procedure. But the master cylinder bleeding procedure just says to pump the pedal while using your finger on the master cylinder output holes as a valve so that air does not get sucked in. It seems as though this is just to speed up the overall bleeding process rather than to do something that regular bleeding at the nipples wouldn't achieve.
I've also got a space servo, so I will see if the gap can be set before I do it for real on the car. I suspect that trial and error can be used to set this gap. Just need to pick up the servo from where it's stored in the warehouse at my workplace.
Edited by rcx106 on Thursday 18th December 11:53
Edited by rcx106 on Thursday 18th December 11:55
andyiley said:
I think it just looks like a spanner with a very large offset to allow the locknut to be slackened to allow the t-bar to adjust the "nose" and then lock it back up.
If you look at the picture diagram in the bottom left it shows the main special tool which measures the gap. The spanner is a second tool to adjust it.To be honest, it does look like I can do this via trial and error. The gap needs to be nil on assembly. If I wind out the adjuster to create a negative gap then the servo and master cylinder won't mate. From there I can wind in step by step until they just mate with zero gap.
I opened this thread before I remembered that I have a spare servo and can figure this out on my bench without taking my car off the road!
stevieturbo said:
Surely you would feel any play at the pedal to know if this needed adjustment ?
You dont seem to mention there is play so it is unlikely there is an issue there ?
Also, allowing the master to run dry is senseless, as a dry system can often be a pain to bleed.
Just depress the brake pedal slightly and secure it pressed down. This covers the holes in the master cylinder to the reservoir, and prevents fluid movement and loss when hoses are removed.
You'll get a few drips, but most of the fluid in the system will be retained making bleeding a simple task, often gravity dripping will sort it.
My issue is with adjusting the gap after I change my master cylinder, which is the next step I'm looking to take. I've bled and bled and dunno what else to do. Other threads have said that master cylinder may be at fault if bleeding does not fix things.You dont seem to mention there is play so it is unlikely there is an issue there ?
Also, allowing the master to run dry is senseless, as a dry system can often be a pain to bleed.
Just depress the brake pedal slightly and secure it pressed down. This covers the holes in the master cylinder to the reservoir, and prevents fluid movement and loss when hoses are removed.
You'll get a few drips, but most of the fluid in the system will be retained making bleeding a simple task, often gravity dripping will sort it.
S0 What said:
How did you bleed the brakes? if by the usuall pedal pumping to the floor you may have killed the master seals, they spend a lot of thier life only traveling a few mm in the cylinder, this wears the cylinder and creates a ridge at the end of the seals normal travell, pumping the pedal hard and with a longer travell and the seal tips get damaged by the ridge, just a posability ?
I've not had to adjust a master/servo for the last 30 odd years but it might be an outside posability, it would be one of the last thoughts for me in a situation like yours though.
Makes sense. The master cylinder has been on the vehicle for 140'000 miles. I have a new one off a later Vitara which has done 23'000 so may as well fit it. Regarding the gap, I will see if I can set it by trial and error. I've asked on the Vitara forum and everyone's answer to setting the gap was to ignore it and just swap the cylinder over.I've not had to adjust a master/servo for the last 30 odd years but it might be an outside posability, it would be one of the last thoughts for me in a situation like yours though.
I initially bled the system with a vacuum pump but the brakes were not firm after that. So I then bled the master cylinder using the brake pedal because that's what the factory manual said to do. I didn't quite get what the master cylinder bleeding achieves seeing as it's essentially the same as opening the nipple at the calipers when the system is under pressure, the only difference is you're using your finger as a valve and you're doing it at the master cylinder outlet (having disconnected the outlets). When the brakes were still not firm after that (and did of course then rebleed the entire system again), I fitted a Goodridge speed bleeder at the further most nipple. This is a nipple with a build in valve and allows me to do fast pumps that apparently help get air out of the master cylinder. When that failed I decided it's time to try a new master cylinder which is where I'm at now.
Dunno what the illiterate guy two posts above is saying. Never heard his theory before and the system was bled according to the factory manual. Gonna see about getting his post removed.
Edited by rcx106 on Saturday 20th December 18:16
Edited by rcx106 on Sunday 21st December 07:32
imagineifyeswill said:
Ive been a mechanic for 40 years and come across many weird and wonderful problems but in all that time Ive never had to adjust the rod clearance in a servo or ever known anyone else who has.
It's not me saying it needs to be done; it's the factory manual, which says it needs to be done each time the master cylinder is removed. But yes, seems here and on the Vitara forum no one bothers.S0 What said:
Does it have a lite laden valve on the rear axle?
some vehicals are just pigs to bleed, from fiestas that only bleed up when the rear is 3 foot higher than the front to vans that have to have the LLvalve bled before the rear cylinder/calipers, some have the master at an angle but that type usually have a seperate bleed nipple at the very end to bleed the master first, speaking of which some just need the master bleeding seperate, i've changed literaly hundreds of certain old ford master cylinders (all identical) and some have just needed the master bleeding but most(like 98%) havn't, go figure
The air in the system isn't allways pushed through the system in one large slug of air, the fluid may take small bubbles at a time from trapped air pockets, it all depends on the pipe routing/design/alterations, cars can have moods which is why most mechanics refer to them as female
There is a proportioning valve at the rear, which proportions the brakes depending on the load in the rear of the vehicle.some vehicals are just pigs to bleed, from fiestas that only bleed up when the rear is 3 foot higher than the front to vans that have to have the LLvalve bled before the rear cylinder/calipers, some have the master at an angle but that type usually have a seperate bleed nipple at the very end to bleed the master first, speaking of which some just need the master bleeding seperate, i've changed literaly hundreds of certain old ford master cylinders (all identical) and some have just needed the master bleeding but most(like 98%) havn't, go figure
The air in the system isn't allways pushed through the system in one large slug of air, the fluid may take small bubbles at a time from trapped air pockets, it all depends on the pipe routing/design/alterations, cars can have moods which is why most mechanics refer to them as female
Good to know some vehicles are just pigs. I'll try doing the master cylinder again and then I'll try some angles, and bleed in a different order! But, I'm going to swap the master cylinder anyway as I have a low mileage one lying around.
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