brake pedal sticking

[spud]

Hi all,
When I bought my HPE VX nearly a year ago it came with a strange/interesting brake fault that I haven't been able to fix yet... The pedal stays down after you remove your foot. So far I've replaced the master cylinder, flexi pipes and all the fluid is brand new. Calipers are fine and not sticking. A few people have suggested it's the linkage- on right hand drive cars there is a linkage system that connects the pedal across to the other side of the car to reach the master cylinder which is not relocated for rhd. Apparently it rusts up through lack of use and causes the pedal to stick... Well, admittedly I don't want to have to go to the trouble of removing it all to clean it up because it looks like a PIG of a job but... I'm not convinced it's that at fault anyway. I'm thinking it's the servo because it doesn't stick when the engine isn't running.
I'm a competent but very basic mechanic and I don't know if a servo could do this. The brake pedal is staying down around 75% of the time after I remove my foot from the pedal. It doesn't matter if I've pressed it really hard, like an emergency stop, or really softly. It just stays down at the point you pressed it to, so it isn't as though it was a certain point on it's travel. It's easily brought back up by me hooking my toes under it and lifting it up- takes no effort at all.
Anyone care to offer an opinion?

Thanks,
Andrew.

[hutch6610]

Wow haven't been here for a long time ... but here goes.
The reason your pedal sticks down only when the engine runs is because the servo gives you more travel on the linkage and you reach the sticky point - because the servo assistance helped you reach this magic point.

Please do not take out and replace the servo because i doubt that's your problem and don't take the whole linkage out just to check.........YET
Faulty servos don't stick.
Now i cant be 100% positive without looking at your car but usually (have had a few Beta's with your problem) the bell-crank behind the servo sticks - how do you reach this?

Well, drop the plastic cover under the dashboard from the passenger side foot well.
If you look closely you will see a black blow moulded plastic sound proof cover which is trapped under a 13mm bolt securing the dashboard onto it.
You have two choices here release the dashboard completely so you can remove the item intact or butcher it (just slit it with a knife so you can slide it off (i would because you can just stick it back together after and no one will know)

Once you have this item removed you will see the bell-crank case attached to the firewall/bulkhead - there should be a locking nut and bolt running vertically through it.
The four nuts and washers around it secure the servo to the bulkhead by the way.
 
Remove the Philips screws that hold the black painted access cover to this box so that you can have a look inside.
You can undo the bolt now a turn or two and lubricate the crank with oil until it loosens up and fingers crossed that should do the trick.

Please try this first before you go any further "pig of a job" is correct with an engine and dashboard in the way.

You bought the silver HPE VX in Taunton ? - i spoke with the seller and he thought it was the master cylinder, of course being a sly git trying to get the car a little cheaper for a friend i did not mention the possible cause 
Anyway too late you got there before me!

Good luck.

[rossocorsa]

I knew someone once who had the linkage actually shear and snap, due to the seizure the rods were flexing and eventually gave up so pig of a job it may be but one that does need doing

[spud]

OK guys, thanks for the replies. Hutch, what you say makes sense- I'll follow your advice and have a look at what you describe. And yes, that was where the car came from. Haven't had the chance to use it much yet due to time constraints but hopefully will be using it very soon. Took it for it's mot test yesterday and all it failed on was this brake pedal issue. Tester commented on it's excellent overall condition. The test station I use is 40 miles away as it was close to my old house and I've just carried on using him- apart from me having got to know him over the years he doesn't charge me for any test failures... even if it fails two or three times. That kind of garage man is worth his weight in gold! So being 40 miles away gives me the perfect opportunity to have a blast in the car as it's all A and B roads to get there- I had a very enjoyable drive!
I'll post back here when I've had a look at what you suggest.

Thanks again,
Andrew.

[MattNoVAT]

Welcome back Hutch - We've missed you!

Wow haven't been here for a long time ... but here goes.

[hutch6610]

Cheers Matt.

I agree with rossocorsa - you can't take a chance, these things are 25 plus years old!
In this case though its not a severe seizure ........ famous last words.

It is however just a shot in the dark on my part guessing the problem lies behind the servo.
The weakest part in my eyes is the vertical pin that connects the linkage to the bell-crank, rarely have i seen one that has been removed, lubed and put back and it will wear - left long enough it will shear.

You can lubricate this part also Andrew, just follow the linkage toward the expansion tank - its a pin with a smaller split pin stopping it from coming out at the end of the brake adjustment.
If you remove it the bell-crank is going to spring away because the servo is partially loaded and it will be a little difficult to put back but not impossible.

The other cranks and ball joints under the steering column mount/pedalbox + where the pivots come out into the engine bay are pretty well lubed - the cranks if i remember correctly - have nylon bushes with steel inserts.
In theory should not seize but become a little stiff.
You can also get to these on the drivers side but few people check the one behind the servo or know its even there.

Your car Andrew was "restored" by Chris Bastow, you did see all the photos?

[spud]

Your car Andrew was "restored" by Chris Bastow, you did see all the photos?

Thanks for those further details Hutch. Planning to have a look at it tomorrow, weather permitting. (my garage is full of another project at the moment...)
Yes, I actually have all the photos on a disc.

Andrew.

[spud]

Hutch,
I found the cover you described and I removed it. The mechanism in there seems very clean and definitely not rusty- I can clearly see all the moving parts moving correctly when the pedal is pressed. I drenched it in WD40 and pressed the pedal around 100 times to work it in there. I then took it for a short drive and in perhaps 50 brake applications it stuck four times which is an improvement but I think I will remove the entire linkage and clean it up as it's the only way to prove it either way really...

Any advice regarding the lube guys? Oil or grease?

Andrew.

[spud]

Well, I'm pleased to report that the problem is now cured! 

Hutch- you were EXACTLY right in your diagnosis. The vertical bolt which acts as the fulcrum for the lever behind the servo was overtightened and was preventing correct movement. The other day all I did was spray it with WD40; I didn't actually loosen it. Today I loosened it and tried the pedal- it was immediately apparent that this was probably the cause of the problem as the pedal was so much easier to press down. I hadn't thought of it as overly difficult to press down in the first place mind- it felt fine. But after loosening it I sprayed it again and took it for a drive with the bolt very loose- the pedal never stuck once! Problem solved. Thank you so much! I only wish I'd asked you before buying the £80 master cylinder last year...

What I want to know now is did Fiat/Lancia really design it this way or is my car missing a part...? On my car the L shaped lever contained within the bolted on housing is held in place purely by the bolt/nut. Consequently when said bolt/nut is tightened it restricts the movement of the lever as it is clamping it in the housing 'sandwich'. I notice you said it should be a locking nut- mine is just a plain nut. I'm guessing that is the root of the problem on my car- a locking nyloc nut would remain in place even when not tightened right up to the housing whereas the normal nut on mine was very tight resulting in over-clamping. Should there not be any washers or a sleeve of some kind?

Anyway, for now I'm going to replace the normal nut with a nyloc type and take it back for it's mot certificate which it should now sail through effortlessly... unless, of course, something else has gone wrong during the last few days... which it could have... it is a Lancia afterall...

Andrew.

[spud]

...take it back for it's mot certificate which it should now sail through effortlessly...

It did! 

Andrew.