The dreaded handbrake!

Started by scm2004red, August 7, 2020, 14:46

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scm2004red

Discovered that my car has a non existent handbrake on the RHS, LHS fine, footbrake OK but no effect whatsoever on handbrake. Full of dread that it might be the seized cable syndrome as I found the caliper lever pulled  full up, I have disconnected the cable at the handbrake lever end and pulled the outer sheath out of the stop at the caliper end (the clevis pin on the end of the cable is seized in the caliper lever at the moment and resisting all attempts to remove it, might have to resort to the dremel!) and can move the inner on the cable freely thank goodness.

After a liberal dose of various lubricants, I can now move the caliper operating lever fairly easily by hand, but it still does not seem to operate the brake. Having difficulty getting my head round what happens when the lever is operated, does it just mechanically push the inner piston out via a push rod?

Presumably this means I have a stuck piston, despite the footbrake seeming to work ok?

Helpful suggestions welcome

MR2 Red Edition 2004
Porsche 924 1984

Carolyn

Quote from: scm2004red on August  7, 2020, 14:46Discovered that my car has a non existent handbrake on the RHS, LHS fine, footbrake OK but no effect whatsoever on handbrake. Full of dread that it might be the seized cable syndrome as I found the caliper lever pulled  full up, I have disconnected the cable at the handbrake lever end and pulled the outer sheath out of the stop at the caliper end (the clevis pin on the end of the cable is seized in the caliper lever at the moment and resisting all attempts to remove it, might have to resort to the dremel!) and can move the inner on the cable freely thank goodness.

After a liberal dose of various lubricants, I can now move the caliper operating lever fairly easily by hand, but it still does not seem to operate the brake. Having difficulty getting my head round what happens when the lever is operated, does it just mechanically push the inner piston out via a push rod?

Presumably this means I have a stuck piston, despite the footbrake seeming to work ok?

Helpful suggestions welcome



You're probably on the right track.  The hydraulics exert so much more pressure than the cable, so the foot brake can shift a stuck piston just enough while the hand brake won't.  Yes it's a push rod acting on the piston.

It does sound like a stuck piston.

The caliper can be overhauled with a readily available kit, or you can buy a refurbished one for decent money.
Perry Byrnes Memorial Award 2016, 2018.  Love this club. 
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scm2004red

Thanks, I have debated rebuilding the caliper, but by the time I buy any wind back tools and special nuts or whatever, seems likely that a recon unit may be worthwhile. Any suggestions as to sourcing one?
MR2 Red Edition 2004
Porsche 924 1984

m1tch

I have a pair of Budweg new calipers from brakeparts.co.uk, no core charge so I kept my OEM ones to rebuild at some point.

My cables are slightly stiff but can free them up fine for the MOT etc, worth making sure that the spring back there is also oiled/greased up.

I would also look to try and 'reset' them by loosening off the cables on the inside of the car, then starting the car and pumping the brakes a lot. The calipers themselves self adjust whilst driving, I have found on mine if you free off the cables and make sure that the spring back there is free (and the pivot arm), then you can usually reset them by keep pressing the brake. You can then tighten up the cables on the handbrake and try that - you can also see if the adjustment is even as well if both cables have adjusted the same in the car.

Worth trying before looking for a recon unit - mine were original on around 175k miles before I swapped them out, think my cables are original.

scm2004red

Thanks. An afternoon of drilling and drifting out the seized clevis pin seems to have shaken the handbrake mechanism up such that I can feel it operate a brake (just) by hand. Made a new clevis from the shank of a bolt and need to connect up the handbrake end to see what happens. I also need to replace the rubber boot at the clevis end (someone here suggested an MGF gear cable end rubber cover, so need to get one of these). Would like to get some oil down the cables for peace of mind when I can figure a way of doing it without swimming in oil. Then I might think of servicing the other side.

Have now expired in dripping perspiration and need a beer and a shower!
MR2 Red Edition 2004
Porsche 924 1984

Gaz mr-s

I'm the one who's suggested the MGF gear cable bellows. Trim them to length & lube the inside & 'screw' them on.
I have also been working on the r/h side cable yesterday & today. Drop the cable from the support bracket to let them lie down to the ground. Raise the inside end vertically. If you have something like a small rubber gaiter cable tie it to the outer & use as a 'funnel' to drip a penetrating oil or if none, 3 in 1 oil.

It takes AGES to get it through to the far end. Unless out at it early, don't expect to be finished the same day.
I've done both cables twice in the last 18 months or so.  My car passed the MOT 2 days ago, but the tester noticed that the lever is not returning to the 'off' stop.  After all my work it still isn't. (New calipers)  The cable seems pretty free push-pulling, but operation of the handbrake is jerky.  Grrr.....

MRSwede

Is there a difference between the Pfl and Fl cables ?
Ordered a pair with Fl spec, but guessing that you still have to remove the tank on a Fl

Carolyn

I'm not aware of a meaningful difference.  There is, however, a left and a right hand cable - they are slightly different lengths.  The tank has to be lowered a few inches - rather than be removed.
Perry Byrnes Memorial Award 2016, 2018.  Love this club. 
https://www.mr2roc.org/forum/index.php?topic=63866.0

ptennisnet

They are different lengths for PFL and FL.  The RHS PFL part number is 4642017091 and (according to the Blueprint parts finder) is 1585 mm (p/n ADT346300).  The RHS FL part number is 4642017100.  When this is punched into the blueprint site the length is 1610 (p/n ADT346361).  I have fitted a FL brake cables to my PFL and they were long and a bit loopy.  The right hand side one didn't last more than a couple of years and I think the extra length meant a bend radius was a bit tight.  In my mind this contributed to the failure but they were eurocarparts cables so that may also be the cause.  I did both cables first time round and the euros cable still works on that side.  The correct length blueprint cable has been good for 2 years so far on the RHS.

MRSwede

Quote from: ptennisnet on September 22, 2020, 17:18They are different lengths for PFL and FL.  The RHS PFL part number is 4642017091 and (according to the Blueprint parts finder) is 1585 mm (p/n ADT346300).  The RHS FL part number is 4642017100.  When this is punched into the blueprint site the length is 1610 (p/n ADT346361).  I have fitted a FL brake cables to my PFL and they were long and a bit loopy.  The right hand side one didn't last more than a couple of years and I think the extra length meant a bend radius was a bit tight.  In my mind this contributed to the failure but they were eurocarparts cables so that may also be the cause.  I did both cables first time round and the euros cable still works on that side.  The correct length blueprint cable has been good for 2 years so far on the RHS.
Ok Thanks,
Is there another routing on the Fl since they are longer ?

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