Rev1 Excessive Brake Travel after bleeding??

[IMR2T]

Going to order new copper washers and nipples.

Are the nipples on all Revs the same, ie 8mm?

[stuMR2lee]

I've seen them ranging from 7mm to 10mm! 8mm seems to be the norm.

Just ordered myself a set of 4 Bremtech ones from Brakes International for £5.99 on eBay. Hopefully they'll be fine.

Correct size is M7x1.0 I believe but oem ones are slightly longer on the front than the rears.

[IMR2T]

Cheers mate, just off the phone to them.

Ordered stainless steel banjos, new washers and nipples front and rear.

Is there a compound or tape I can't wrap the threads with to ensure they're air tight?

[stuMR2lee]

I wouldn't. The threads don't need to seal its just the end of the bleed screw that seals. Ptfe tape I've found means I can't get the bleed screws tight enough.

Edit: You can use a bit of grease around the threads, only when you are bleeding, if you want but it shouldn't be necessary. I do sometimes when using the vacuum bleeder.

[bobhatton]

Ordered stainless steel banjos,

How are you going to fit them? Do you have stock rubber hoses?


The hand brake is self-adjusting, it should come up about 4 to 6 clicks, if it is any tighter the self-adjusting will not work.
With the foot pedal pressed hard down keep working the hand brake and it will adjust up, you will also feel the foot brake is better after too as it takes the free play out of the pads.

[stuMR2lee]

Not doubting your wisdom or experience Bob but from the videos I previously posted can you explain how the handbrake 'self-adjusts'?

The conclusion reached by the author of those videos (although the English isn't great) is that the handbrake does not 'self-adjust' by anything other than very fine movement as nothing inside the caliper rotates. The threaded shaft is on a spring so returns. The handbrake function is a simple pin on a cam that lifts the shaft & piston together.

http://sandbag82.blog.me/220261759217

Having recently stripped several calipers a down to the handbrake mechanism I cannot see any ongoing self adjusting mechanism in the caliper.

This has bugged me for a while as I like to understand exactly how the calipers work. I've been searching for a definitive logical answer. Since the piston merely rotates up & down the threaded shaft winding it in or out will not re-set anything that I can see.

[bobhatton]

Not doubting your wisdom or experience Bob but from the videos I previously posted can you explain how the handbrake 'self-adjusts'?

The conclusion reached by the author of those videos (although the English isn't great) is that the handbrake does not 'self-adjust' by anything other than very fine movement as nothing inside the caliper rotates. The threaded shaft is on a spring so returns. The handbrake function is a simple pin on a cam that lifts the shaft & piston together.

http://sandbag82.blog.me/220261759217

Having recently stripped several calipers a down to the handbrake mechanism I cannot see any ongoing self adjusting mechanism in the caliper.

This has bugged me for a while as I like to understand exactly how the calipers work. I've been searching for a definitive logical answer. Since the piston merely rotates up & down the threaded shaft winding it in or out will not re-set anything that I can see.

Have you read through the info in the BGB, it is all in there

The adjusting bolt turns when the hand brake is pulled up, has to have 5 to 8 clicks to let the cable go back to its stop and then it will adjust.

Every week or two I push the foot brake hard down and work the hand brake 12 times or so and the adjustment is done.

I am sure you know the piston cannot just be pushed back in like the front, it has to be turned, well it is the hand brake that has done the adjustment to bring the piston out close to the disk.

[stuMR2lee]

Thanks Bob. There is a lot of Mis-information about. Will have a read of the BGB again and have a play with a spare caliper to see if I can replicate this.

[stuMR2lee]

Relevant BGB section:

http://staff.osuosl.org/~bkero/bgb/mech ... system.htm

Still think getting the initial interference fit right initially is key as per Paul Woods method.

Personally I prefer 2-3 clicks on the handbrake but appreciate this will give no ongoing 'self-adjustment'.

It would seem from what Bob said that many us possibly over tighten our handbrakes.

[stuMR2lee]

Just had a go with a spare rear caliper. Couldn't replicate the handbrake lever adjustment by hand. Perhaps it's different when working in conjunction with pumping the pedal. The cam does have a sort of jumping movement with more travel.

Edit: BGB, having read it again, doesn't seem to mention auto-adjustment other than by pumping the piston out.

But with air (simulating brake fluid) the piston comes out to meet the pads (block of wood in this case) and stays out to take up the slack. So something must be rotating inside and suggests that it's the pumping up of the pedal that adjusts the piston. The mechanism inside is clearly more complex than thought by some.

This gets more confusing! Setting the piston a few degrees winding out or 180+ made no difference in my test. In fact not winding it out at all seemed to make no difference. The piston still comes out with pressure and stays out.

So many posts and theories online about how these things work. Every forum has a different opinion. Some people seem to get lucky setting up their brakes/calipers whilst others struggle.

One for Mythbusters maybe!

Anyway back to the OP's initial problem. Got to be air in the system as originally stated. My bleed screws showed up today (less than 24 hours after ordering). Minor annoyance being that they are 7mm. Once air is out the Pistons can be pumped out more effectively. Then all should be good.

[IMR2T]

I wouldn't. The threads don't need to seal its just the end of the bleed screw that seals. Ptfe tape I've found means I can't get the bleed screws tight enough.

Edit: You can use a bit of grease around the threads, only when you are bleeding, if you want but it shouldn't be necessary. I do sometimes when using the vacuum bleeder.

Sorted makes sense

[IMR2T]

Ordered stainless steel banjos,

How are you going to fit them? Do you have stock rubber hoses?


The hand brake is self-adjusting, it should come up about 4 to 6 clicks, if it is any tighter the self-adjusting will not work.
With the foot pedal pressed hard down keep working the hand brake and it will adjust up, you will also feel the foot brake is better after too as it takes the free play out of the pads.

Hi Bob, Im assuming theres another complication ahead of me...hence why your asking how am I going to fit them?

I do have stock rubber hoses, why do you ask?

LOVING the handbrake adjustment insight, keep tips like that coming

[IMR2T]

Just had a go with a spare rear caliper. Couldn't replicate the handbrake lever adjustment by hand. Perhaps it's different when working in conjunction with pumping the pedal. The cam does have a sort of jumping movement with more travel.

But with air (simulating brake fluid) the piston comes out to meet the pads (block of wood in this case) and stays out to take up the slack. So something must be rotating inside and suggests that it's the pumping up of the pedal that adjusts the piston. The mechanism inside is clearly more complex than thought by some.

This gets more confusing! Setting the piston a few degrees winding out or 180+ made no difference in my test. In fact not winding it out at all seemed to make no difference. The piston still comes out with pressure and stays out.

So many posts and theories online about how these things work. Every forum has a different opinion. Some people seem to get lucky setting up their brakes/calipers whilst others struggle.

One for Mythbusters maybe!

Anyway back to the OP's initial problem. Got to be air in the system as originally stated. My bleed screws showed up today (less than 24 hours after ordering). Minor annoyance being that are 7mm. Once air is out the Pistons can be pumped out more effectively. Then all should be good.

The variety of advice can be frustrating, which is why its always good having guys like yourself and Bob onboard to cut to the chase

[stuMR2lee]

Haha. Thanks. I'm no expert. I just like to know how things work and having fully refurbished another 4 sets of calipers in the last week or so I've been doing a fair bit of research.

One of them was having bleeding difficulties like yourself but the rest were fine. Turns out his was air as well.

[bobhatton]

Ordered stainless steel banjos,

Hi Bob, Im assuming theres another complication ahead of me...hence why your asking how am I going to fit them?

I do have stock rubber hoses, why do you ask?

LOVING the handbrake adjustment insight, keep tips like that coming

The banjos come as part of the hose, they cannot be fitted afterwards.
With stainless hoses some use stainless banjo ends but have to be crimped onto the hose, reusable hose ends are an MOT fail.

[stuMR2lee]

I think he's referring to the actual Banjo Bolts which are of course separate to the hoses rather than the actual Banjo itself.

Example: http://pages.ebay.com/link/?nav=item.vi ... 1556822793

[whippet]

You need to determine where the actual fault lies, if you get some hose clamps like the ones in ebay link, you will need 4 clamps in total.
Camp off all 4 hoses, pedal should be hard and to the top, if not masre cyl is faulty or needs bleeding with clamps stil on.
Take off front clamps one at a time and see what difference it makes to padal, then do the same on rear, this will show the area needing to be worked on.

Before you do this, heve someone pump up and hold pedal while you check each hose to see if ant of them are bulging.

You should be able to get clamps locally from somewhere like Halfords.

Hope this helps.

Cant post ebay link, but look for brake hose clamps, and check the Draper ones.

[IMR2T]

Hi Bob, Im assuming theres another complication ahead of me...hence why your asking how am I going to fit them?

I do have stock rubber hoses, why do you ask?

LOVING the handbrake adjustment insight, keep tips like that coming

The banjos come as part of the hose, they cannot be fitted afterwards.
With stainless hoses some use stainless banjo ends but have to be crimped onto the hose, reusable hose ends are an MOT fail.

I get you now, yeah just meant the bolt that secures the banjo to the caliper.

[IMR2T]

After fitting the stainless banjos, the new copper washers and 4 new nipples the pedals better but not great tbh. A hard push takes it 3/4 of the way through it's travel once the engines started. It always goes further with the engine on compared to off(assuming that's my master cylinder helping out)

Over halfway does lock up the wheels(my ABS light is on so it would seem it's not working)

At some point I'll fire on new discs and pads and Im sure the travel will improve as current brakes are halfway through their life but possibly with my Rev1 master cylinder operating the larger calipers it'll always travel a bit further.

Can you bleed the master cylinder seperately while its in the car? I kp seeing this bench bleeding but not wanting to take it out if I don't nd to.

[whippet]

You can bleed master cyl in car, get someone to press pedal, then loosen outlet pipe tube nut on cyl, tighten tube nut, release pedal and repeat till no air comes out. Pedal goes down further with engine running as the servo assists effort needed.