9" Servo upgrade issue

Hi i recently had the old 8" servo for a 9" and 22mm master cylinder. However im finding the brakes are binding after 10 miles to the point the wheels wont turn!

Ive read a few things and i think i need to loose the locking nut and wind the clevis pin in to give the system some slack. fingers crossed that works as its already cost me a bloody fortune!

Now to the Question: is it possible to remove the servo and adjust the clevis pin without having to bleed the system, ie can i unbolt the master cylinder, then servo - will there be enough room?

Thanks.

 

technically you can, but I would doubt that you will be able to move the m/c out of the way enough to pull the servo out.
Not sure I really understand your issue though. You say the brakes are binding after 10 miles, are the brakes hot? Sounds like it could be a sticking caliper.
By adjusting the clevis pin, you are only changing the mechanical movement of the system, ie, winding it in will mean that the pedal has to travel further to the floor before it starts to push on the servo and m/c.
 
The amount of fluid in the system after bleeding is static, when you take pressure off the pedal the m/c pulls the fluid back, retracting the caliper. If you wind the clevis pin in, then more fluid will be pulled back, pulling the calipers more open (unless the calipers are fully open, in which case not a lot will happen). Conversely, when you press the pedal, it will require more travel to push the pads to contact the disk.
I wouldn't change the position of anything in the mechanical linkage without a re-bleed to make the sure the pad-disc gap is correct. At which point, you've not actually adjusted anything other than where in the pedal travel the brakes start to bite.
Appreciate there is a lot of info there, but in short, I don't think the issue is going to be solved by adjusting the clevis pin.

paceman said

technically you can, but I would doubt that you will be able to move the m/c out of the way enough to pull the servo out.
Not sure I really understand your issue though. You say the brakes are binding after 10 miles, are the brakes hot? Sounds like it could be a sticking caliper.
By adjusting the clevis pin, you are only changing the mechanical movement of the system, ie, winding it in will mean that the pedal has to travel further to the floor before it starts to push on the servo and m/c.
 
The amount of fluid in the system after bleeding is static, when you take pressure off the pedal the m/c pulls the fluid back, retracting the caliper. If you wind the clevis pin in, then more fluid will be pulled back, pulling the calipers more open (unless the calipers are fully open, in which case not a lot will happen). Conversely, when you press the pedal, it will require more travel to push the pads to contact the disk.
I wouldn't change the position of anything in the mechanical linkage without a re-bleed to make the sure the pad-disc gap is correct. At which point, you've not actually adjusted anything other than where in the pedal travel the brakes start to bite.
Appreciate there is a lot of info there, but in short, I don't think the issue is going to be solved by adjusting the clevis pin.

Hi there, thanks for your detailed reply. I read a few things that have mentioned there should be a little play in the clevis pin, and mine is pretty tight without any pressure on the brake. I thought this might be causing a constant drag and thus excess heat that might cause things to bind.

When it first did it i was told it was because of a sticking caliper - which has now been replaced along with discs and pads,  but  the problem still remains. The brakes get so hot they smoulder!

It may be easier to make the adjustment on the linkage rods first. Have you seen this post? Turned out to eb a servo issue…. https://www.clubgti.com/forums/index.php?threads/mk1-golf-brakes-sticking.286435/

Yep read that post, it's where i first started researching. Probably just going to get my mechanic back to take a look! I thought if it was just a little adjustment i could have a go! I know one end of a spanner from the other but thats about it!

To be honest, I've never been aware of it as an issue, I may have to go and check my linkage setup whilst I can still get to everything! Make sure you share the solution when you find it.

When i first fitted a 9 inch servo,  a good few years ago now there was a measurement to cut things down to to make it fit / work properly,  no internet, the magazines of the time. I actually fitted four spacers between servo and servo bracket to avoid cutting anything,  worked fine.  You could actually try this first to see if it helps before cutting things.  Its perfectly safe and achieves the same thing..

abfmk1 said

When i first fitted a 9 inch servo,  a good few years ago now there was a measurement to cut things down to to make it fit / work properly,  no internet, the magazines of the time. I actually fitted four spacers between servo and servo bracket to avoid cutting anything,  worked fine.  You could actually try this first to see if it helps before cutting things.  Its perfectly safe and achieves the same thing..

Thanks that's a great idea, I'll raid my washers and give it a go! 
👍🤞

Another issue that I have seen for "Brakes getting hotter than a firecracker" is the condition of the Rubber hoses to the Calipers and the rear axle.

Over time they can internally break down causing them to become similar to Veins.  The can actually prevent the calipers or rear wheel cylinders from retracting.

I am having this exact issue. 

Did adding spacers or cutting down the servo thread work?

Sorted. Put 4 nuts on the servo to space from the bracket and then refitted. Seems to have done the trick and haven't had to take it all apart again either.