Brake push rod adjustment on a '71, with servo

[billybradshaw]

Evening folks,

I've just assembled a new master cylinder and servo to my '71 bay and I'm left wondering now how I adjust the linkage to obtain the 1mm clearance between the pushrod and the master cylinder. Is this something I can actually achieve on a servo equipped bus? I only ask cos there is a large coil sprin inside the servo which I assume puts the push rod inside the servo in positive contact with the receptacle on the master cylinder pushrod.......

There isn't much in the Haynes regarding this, at least nowt specific for servo equipped models.

Also, it feels as if the brake pedal return spring is tired as it er......doesn't return the pedal, does anybody know where I can get a new one, can't find one listed anywhere............

Any advice would be welcome

Cheers

Ian

 

[Clarkson46]

Custom & Commercial list the return spring in their catalogue but not on line. Ring them on 013272 452297. Their part number is S01947 or s01948 depending on whether it's LHD or RHD

 

[billybradshaw]

Cheers very much Monsieur Clarkson46. I'll see if I can rustle a spring up from them.

Anybody any ideas about the adjustment problem?

Cheers

Ian

 

[Clarkson46]

Same as the non servo system except the clearance is between the pushrod and the servo. Just slack the lock nut and rotate the push rod until you get the correct clearance when the clevis pin is inserted.

 

[billybradshaw]

Thanks again Clarkson46

Hmmmm right, I think my 'problem' has arisen from two areas. a) The pedal return spring appears to be very lame, it can't even support the weight of the pedal and therefore any adjustment just pulls the pedal downward (I guess the spring could be installed incorrectly but I can't see any other way) b) I can feel what I believe to be 'play' in the servo, i.e. a push at the pedal end doesn't seem to create an equal amount of movement at the master cylinder end............

Anyway, it's dark now so I'll have another head scratch tomorrow.

Cheers

Ian

 

[billybradshaw]

Right, it's all sorted, well sort of :mrgreen:

Just need to find the correct spring now, after chatting with Moby on VZi he has a view that the wrong spring might be fitted hence the crap pedal return action.

Would anybody out there with a '71 bus be kind enough to take a picture of the spring they have fitted just so I know which way to start looking???

Cheers folks

Ian

 

[Guest]

ill do it tomorrow when i get home from work.

 

[billybradshaw]

Hey up Johnny,

Yeah if you could get some pics up then great. Give me a few of the basic dimensions too please like the spring diameter and the diameter of the wire used to make it, etc.

Ta very much

Ian

 

[billybradshaw]

Any luck with some pics Johnny?

Cheers

Ian

 

[jenna_uk22]

hey billybradshaw. where did you get a new break pedal return spring from in the end? think mine needs doing (also 71 so any tips would be great) the break pedal stays up but i'm having to pull it up myself at the mo. seen the spring on Just Kampers for £15 but everything i buy from them dont seem to fit. hoping to spot one at Bus Stopover at the weekend

Jenna

 

[billybradshaw]

Morning Jenna,

Sorry kid but I've only just seen your post.

I decided that the spring problem I had was just because it was 37 years old, I mean after 37 years use I guess things will tend to go a bit floppy...............

To get some stiffness back in the spring I heated it with a small blow torch and bent the arm of the spring, i.e. the part which locates in the hole in the bracket that. I'll draw up a pic this weekend and post it so you can see what I mean. It definitely did the trick, the pedal now returns like a good un.

Cheers

Ian

 

[billybradshaw]

OK, as promised, a little diagram to paint a thousand words.

Hope it helps you to sort it out.

Cheers

Ian