Omega Owners Forum
Chat Area => General Car Chat => Topic started by: Lizzie Zoom on 19 January 2022, 12:22:29
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As you may have noted from my other thread a major service I have just carried out, where I have yet again adjusted both the handbrake cable and rear brakes, out of interest I am wondering why we have to adjust both together?
As the handbrake cable is a separate adjustment to the rear shoes, why is it not advisable to just adjust the handbrake cable to achieve the optimum "5 clicks"?
I have faithfully followed the guide on every Omega I have owned, but although to some it may be a stupid question, what is the technical answer please. ??? ??? ;)
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When you adjust the star wheel to the point that it's just backed off a tad from binding the hub, you know that when you pull on the handbrake it should pull evenly on both hubs. If one star wheel is out and one is in, the cable will go tight on the closer side, requiring a mighty pull on the handbrake to get the other side to grip, and this upsets the mot man due to insufficient braking force. ;D. If they are both equal, the handbrake cable should stop both wheels on the roller equally, which just leaves the handbrake cable adjustment to reduce any slack.
Hope that's what you meant anyway. :y
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When you adjust the star wheel to the point that it's just backed off a tad from binding the hub, you know that when you pull on the handbrake it should pull evenly on both hubs. If one star wheel is out and one is in, the cable will go tight on the closer side, requiring a mighty pull on the handbrake to get the other side to grip, and this upsets the mot man due to insufficient braking force. ;D. If they are both equal, the handbrake cable should stop both wheels on the roller equally, which just leaves the handbrake cable adjustment to reduce any slack.
Hope that's what you meant anyway. :y
Yes, thanks YZ250, that is what I wanted to know, and now I do! ;D :y :y
I have wondered that for years!! ::) ;)
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which raise the question of why you use it on an auto? ::) ::) ;)
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which raise the question of why you use it on an auto? ::) ::) ;)
Because you know just how weak the park lock mechanism in the gearbox is?
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which raise the question of why you use it on an auto? ::) ::) ;)
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The "park brake/handbrake" is also the "emergency brake" in the event of rapid brake fluid loss .
selecting P at 100 err I mean 70 won't end well for the gearbox :P
My handbrake is 3 clicks ,TIS says 7 IIRC , I know why too ,but never had an issue at 3 clicks in 20+ years of Carltons and the Omega .
I'm a rebel :D
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Each hub is a separate system. Adjusting just the lever does nothing to allow for wear/binding discrepancies across the axle.
Also if you adjust the lever cable first, then you may not be able to correctly adjust the shoes. The operating lever should always be the last adjustment on any such mechanism.
3-5 clicks is the accepted optimum range as it is enough to ensure application but not too much to allow for stretch and future adjustment. The Omega handbrake mechanism is NOT self adjusting.
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Each hub is a separate system. Adjusting just the lever does nothing to allow for wear/binding discrepancies across the axle.
Also if you adjust the lever cable first, then you may not be able to correctly adjust the shoes. The operating lever should always be the last adjustment on any such mechanism.
3-5 clicks is the accepted optimum range as it is enough to ensure application but not too much to allow for stretch and future adjustment. The Omega handbrake mechanism is NOT self adjusting.
It still makes me wonder why Vauxhall (and perhaps other manufacturers) did not design the system to automatically adjust the handbrake cable / rear pads together. ::) ::)
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Each hub is a separate system. Adjusting just the lever does nothing to allow for wear/binding discrepancies across the axle.
Also if you adjust the lever cable first, then you may not be able to correctly adjust the shoes. The operating lever should always be the last adjustment on any such mechanism.
3-5 clicks is the accepted optimum range as it is enough to ensure application but not too much to allow for stretch and future adjustment. The Omega handbrake mechanism is NOT self adjusting.
It still makes me wonder why Vauxhall (and perhaps other manufacturers) did not design the system to automatically adjust the handbrake cable / rear pads together. ::) ::)
I've never seen a system which does that. Adjusting the shoes so that they just contact the drum, and then making the cable tension keep them there has been the procedure for decades. Stretching the cable can be a direct result of adjusting it without first ensuring the rest of the system is in spec.
What's under your car is the basic layout for a drum type handbrake. The more sophisticated complicated ones use a separate cable and adjuster for each brake. They don't work any better.
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The "park brake/handbrake" is also the "emergency brake" in the event of rapid brake fluid loss .
selecting P at 100 err I mean 70 won't end well for the gearbox :P
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so why wear it out using it when you don't need to ::) ::)
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Each hub is a separate system. Adjusting just the lever does nothing to allow for wear/binding discrepancies across the axle.
Also if you adjust the lever cable first, then you may not be able to correctly adjust the shoes. The operating lever should always be the last adjustment on any such mechanism.
3-5 clicks is the accepted optimum range as it is enough to ensure application but not too much to allow for stretch and future adjustment. The Omega handbrake mechanism is NOT self adjusting.
It still makes me wonder why Vauxhall (and perhaps other manufacturers) did not design the system to automatically adjust the handbrake cable / rear pads together. ::) ::)
They are separate and independent systems.
The hydraulic caliper/cab service brake is self adjusting by design.
Brake shoes are a bit more mechanical in how they apply force. In a service applicantion these have a self adjusting element to allow for the significant increase in friction material wear. In parking/emergency brake applications these are almost never self adjusting.
BMW and Mercedes have both been long term users of rear discs with the parking brake being contained within the hub drum of the disc brake. The Omega is no different in this regard.
Using the service brake caliper/pad is at first glance a simpler arrangement. The reality is the polar opposite. The mechanism to actuate the parking brake is a screw mechanism behind the piston and these can fail/bind, also the mechanical versions are prone to releasing as the pads and discs cool. Electrical versions use a motor to drive the mechanism to apply the piston which over applies itself in order to allow for cooling, but eventually this strips the gears within it and they fail. Usually when applied.
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The "park brake/handbrake" is also the "emergency brake" in the event of rapid brake fluid loss .
selecting P at 100 err I mean 70 won't end well for the gearbox :P
.....
so why wear it out using it when you don't need to ::) ::)
Using it stops the cable (which is plastic lined) and mechanisms from seizing .
Also , in the event of someone crashing into the Omega while it's parked (which has happened to me many times >:( ) it puts less strain on the park pawl
Failure of the pawl could see 2 ton of Vauxhall's finest opel rust on it's merry way down the road
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Each hub is a separate system. Adjusting just the lever does nothing to allow for wear/binding discrepancies across the axle.
Also if you adjust the lever cable first, then you may not be able to correctly adjust the shoes. The operating lever should always be the last adjustment on any such mechanism.
3-5 clicks is the accepted optimum range as it is enough to ensure application but not too much to allow for stretch and future adjustment. The Omega handbrake mechanism is NOT self adjusting.
It still makes me wonder why Vauxhall (and perhaps other manufacturers) did not design the system to automatically adjust the handbrake cable / rear pads together. ::) ::)
Its an ATE system, used by loads of manufacturers at the time, very common for larger cars with rear wheel drive and discs.
The basics are this
The handbrake cable must be adjusted such that there is a little slack with the handbrake released, there should be no tension at the operating lever at the rear of the rear brake backplate and the return spring must return the actuating lever to its end stop. This ensures that the brake actuating lever is set to give complete travel.
The shoes are then setup to match the drums (very slight rub on rotation).
The handbrake cable it self shoudl rarely need any adjustment unless its replaced or has stretched following fitment of new.
Rear shoes should only need adjustment for wear. :y
The trick has always been to use the handbrake and slightly apply it for a few seconds when driving at low speed every month or so, this keeps the drum faces clean and helps to stop it seizing up.
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exactly as above.
also to note is that if the handbrake seems to go out of adjustment regularly its worth checking that the cable is not gradually pulling itself through the outer retaining brackets on the rear lower arms.they are only a wound/ bent piece of steel and they can easily 'open up' over the years.especially as they thin with age and rust.
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which raise the question of why you use it on an auto? ::) ::) ;)
Because you know just how weak the park lock mechanism in the gearbox is?
I've yet to break a pawl on an auto box in 30+ years .... ;)
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The "park brake/handbrake" is also the "emergency brake" in the event of rapid brake fluid loss .
selecting P at 100 err I mean 70 won't end well for the gearbox :P
.....
so why wear it out using it when you don't need to ::) ::)
Using it stops the cable (which is plastic lined) and mechanisms from seizing .
Also , in the event of someone crashing into the Omega while it's parked (which has happened to me many times >:( ) it puts less strain on the park pawl
Failure of the pawl could see 2 ton of Vauxhall's finest opel rust on it's merry way down the road
Dave, You have realised that I'm not being serious ... ::)
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BMW and Mercedes have both been long term users of rear discs with the parking brake being contained within the hub drum of the disc brake. The Omega is no different in this regard. ....
Though my 07 R Class used a disc/drum set up using a foot operated parking/emergency brake, my ML now uses an electric parking brake that operates on the disc.
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BMW and Mercedes have both been long term users of rear discs with the parking brake being contained within the hub drum of the disc brake. The Omega is no different in this regard. ....
Though my 07 R Class used a disc/drum set up using a foot operated parking/emergency brake, my ML now uses an electric parking brake that operates on the disc.
The pedal operation is a variation on the traditional hand operated lever or the old umbrella handle type. The pedal operated mechanism is adjusted in exactly the same way as the hand lever... The ratchet/pawl has a fixed range of motion and the cable connecting the lever to the rear cables is adjusted for length as (very rarely) required. The release handle is a cable or chain (on some '70s models) that is basically an elaborate version of the push button on a traditional handbrake lever.
Switching to electric is probably as much to do with cost to manufacture as much as anything else.
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Thanks for all the feedback on my question :y :y
Now I have to ask; is the, rather antiquated, system any different on the new electric vehicles?
To me, apart from brake cables for the main drums being replaced by hydraulic pipes to brake pads, but still cables being used for hand brakes, with fail safe systems, nothing has really changed since my A40 days.
I know if a engineering system is found to be good the designers stick to it, but what will or can change in the future?
(I am in a questioning mood trying to get my mind off something else..................!!) :P
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The "park brake/handbrake" is also the "emergency brake" in the event of rapid brake fluid loss .
selecting P at 100 err I mean 70 won't end well for the gearbox :P
.....
so why wear it out using it when you don't need to ::) ::)
Using it stops the cable (which is plastic lined) and mechanisms from seizing .
Also , in the event of someone crashing into the Omega while it's parked (which has happened to me many times >:( ) it puts less strain on the park pawl
Failure of the pawl could see 2 ton of Vauxhall's finest opel rust on it's merry way down the road
Dave, You have realised that I'm not being serious ... ::)
But someone else could read this thread :o
it's on the internet :D
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Thanks for all the feedback on my question :y :y
Now I have to ask; is the, rather antiquated, system any different on the new electric vehicles?
To me, apart from brake cables for the main drums being replaced by hydraulic pipes to brake pads, but still cables being used for hand brakes, with fail safe systems, nothing has really changed since my A40 days.
I know if a engineering system is found to be good the designers stick to it, but what will or can change in the future?
(I am in a questioning mood trying to get my mind off something else..................!!) :P
New vehicles use a switch, some cables, an ECU, with at least one electric motor and linkage to do the same job. They're shit. You need to edit your post, and replace antiquated with efficient.
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BMW and Mercedes have both been long term users of rear discs with the parking brake being contained within the hub drum of the disc brake. The Omega is no different in this regard. ....
Though my 07 R Class used a disc/drum set up using a foot operated parking/emergency brake, my ML now uses an electric parking brake that operates on the disc.
The pedal operation is a variation on the traditional hand operated lever or the old umbrella handle type. The pedal operated mechanism is adjusted in exactly the same way as the hand lever... The ratchet/pawl has a fixed range of motion and the cable connecting the lever to the rear cables is adjusted for length as (very rarely) required. The release handle is a cable or chain (on some '70s models) that is basically an elaborate version of the push button on a traditional handbrake lever.
Switching to electric is probably as much to do with cost to manufacture as much as anything else.
I know how they work .... my point was that even MB seem to be moving away from a top hat disc/drum set up in favour of a parking brake that operates on the disc - as you say being cheaper
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;)
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Thanks for all the feedback on my question :y :y
Now I have to ask; is the, rather antiquated, system any different on the new electric vehicles?
To me, apart from brake cables for the main drums being replaced by hydraulic pipes to brake pads, but still cables being used for hand brakes, with fail safe systems, nothing has really changed since my A40 days.
I know if a engineering system is found to be good the designers stick to it, but what will or can change in the future?
(I am in a questioning mood trying to get my mind off something else..................!!) :P
electric hand/parking/emergency brakes seem to be the norm these days ..... presumably cheaper.
Two people I know of that have recently passed their driving test had no idea whatsoever how to do a hill start in their now older cars because they'd learned & passed their test in a car with an auto handbrake or with HOLD assist of some sort.
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Thanks for all the feedback on my question :y :y
Now I have to ask; is the, rather antiquated, system any different on the new electric vehicles?
To me, apart from brake cables for the main drums being replaced by hydraulic pipes to brake pads, but still cables being used for hand brakes, with fail safe systems, nothing has really changed since my A40 days.
I know if a engineering system is found to be good the designers stick to it, but what will or can change in the future?
(I am in a questioning mood trying to get my mind off something else..................!!) :P
New vehicles use a switch, some cables, an ECU, with at least one electric motor and linkage to do the same job. They're shit. You need to edit your post, and replace antiquated with efficient.
In other words it does it's job and has proved the test of time :D ;)
My daughters Grandland X has one of those electric 'hand' brake with a little button to turn it on when stopped. It always intrigues me that I can dis-engage the brakes by just driving against them after being stopped in traffic ;)
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Right upto the point where you can no longer do that...
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Thanks for all the feedback on my question :y :y
Now I have to ask; is the, rather antiquated, system any different on the new electric vehicles?
To me, apart from brake cables for the main drums being replaced by hydraulic pipes to brake pads, but still cables being used for hand brakes, with fail safe systems, nothing has really changed since my A40 days.
I know if a engineering system is found to be good the designers stick to it, but what will or can change in the future?
(I am in a questioning mood trying to get my mind off something else..................!!) :P
New vehicles use a switch, some cables, an ECU, with at least one electric motor and linkage to do the same job. They're shit. You need to edit your post, and replace antiquated with efficient.
In other words it does it's job and has proved the test of time :D ;)
My daughters Grandland X has one of those electric 'hand' brake with a little button to turn it on when stopped. It always intrigues me that I can dis-engage the brakes by just driving against them after being stopped in traffic ;)
I like the BMW (and probably other manufacturers as well) setup that applies park automatically if you open the drivers door while stationary with the Car in D or R..... I can only guess that was developed for our friends over the pond ;D
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It always intrigues me that I can dis-engage the brakes by just driving against them after being stopped in traffic ;)
but the throttle is being pressed too to make it disengage
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I like the BMW (and probably other manufacturers as well) setup that applies park automatically if you open the drivers door while stationary with the Car in D or R..... I can only guess that was developed for our friends over the pond ;D
My ML does this too .... though the R Class before it didn't :-\
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Thanks for all the feedback on my question :y :y
Now I have to ask; is the, rather antiquated, system any different on the new electric vehicles?
To me, apart from brake cables for the main drums being replaced by hydraulic pipes to brake pads, but still cables being used for hand brakes, with fail safe systems, nothing has really changed since my A40 days.
I know if a engineering system is found to be good the designers stick to it, but what will or can change in the future?
(I am in a questioning mood trying to get my mind off something else..................!!) :P
New vehicles use a switch, some cables, an ECU, with at least one electric motor and linkage to do the same job. They're shit. You need to edit your post, and replace antiquated with efficient.
In other words it does it's job and has proved the test of time :D ;)
My daughters Grandland X has one of those electric 'hand' brake with a little button to turn it on when stopped. It always intrigues me that I can dis-engage the brakes by just driving against them after being stopped in traffic ;)
I like the BMW (and probably other manufacturers as well) setup that applies park automatically if you open the drivers door while stationary with the Car in D or R..... I can only guess that was developed for our friends over the pond ;D
Yes, like the chiming sound when the doors are open, which I rather like when I have been in the States. :D ;)
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I haven't specifically tried, but if you open the door in gear to check your position against a kerb whilst in gear, it gets all sorts of pissed off by it... Red messages and lots of angry bonging :D
It doesn't have a hill start function though (as far as I know), so presumably that is a limited plus point to the electric actuators. That said, if you apply the parking brake whilst stationary and in D then it won't drive uphill if you release the parking brake. I presume this is a quirk of it rolling back slightly when the foot brake is released and subsequently binding up the transfer box or the front diff as the parking brake only applies the rears. :-\
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I like the BMW (and probably other manufacturers as well) setup that applies park automatically if you open the drivers door while stationary with the Car in D or R..... I can only guess that was developed for our friends over the pond ;D
Wait until you have to push one of the sodding things for some reason. Equally asinine was Mercedes decision for the gearbox to move into park as soon as the engine stops turning, or not to move out unless it was. After all, no Mercedes has ever failed to start ::)
Combine that with an electric handbrake and what should be a simple scoop it up and and dump it back at the dealer becomes a complex initiative test to move it to, onto and off the truck without doing £17,374,656,483,930,937,547 worth of damage to the trans, brakes, suspension, bodywork and boot mat.
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Intelligent Servo Module is as much an oxymoron as Crawley Luxury. :-X
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Equally asinine was Mercedes decision for the gearbox to move into park as soon as the engine stops turning, ....
I discovered that by accident .... turn the ignition off & it went into Park by itself. I believe there's such a thing as a freewheeling hub to move them if push comes to shove (no pun intended ::))
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Most auto boxes have a cable pull to release the park pawl in the case of an issue (certainly the superior ZF boxes, can't comment on the Mercs but would expect similar).
The later handbrake system with motors is pretty intelligent (its moved on since the days of the VW setup that ate motors) and applies a 'torque', it then checks over the next 15 minutes to ensure the torque is still present and applies more if needed, to overcome disc cool down. Sadly to release them in the event of a full on failure requires the motors being removed and the handbrake wound off (not to hard......if you can get to them so can need wheel removal)
Of course adding things like auto park application etc is just a bit of extra logic in the BCM software.
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Most auto boxes have a cable pull to release the park pawl in the case of an issue (certainly the superior ZF boxes, can't comment on the Mercs but would expect similar).
Both Mercedes and BMW deleted that option many years ago. BMW kept supplying the plastic gadget required to release the park mechanism on X5s until the next model change as that would have meant a gap in the toolkit. That was an interesting - and frustrating - phone call.... German engineers - I suggest that they should have a modern equivalent of the court jester who randomly beats one of them with a big stick to avoid such stupidity.
Easily adding features in software is all very well, but the underlying mechanisms need to be properly thought through and implemented: adding auto release to traditional drum-in-disc handbrakes that had previously never seen a rotating wheel which didn't need large diameter, thick linings, then compounding the mistake with weak plastic gears. Just because you can, doesn't mean you should.
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Most auto boxes have a cable pull to release the park pawl in the case of an issue (certainly the superior ZF boxes, can't comment on the Mercs but would expect similar).
The later handbrake system with motors is pretty intelligent (its moved on since the days of the VW setup that ate motors) and applies a 'torque', it then checks over the next 15 minutes to ensure the torque is still present and applies more if needed, to overcome disc cool down. Sadly to release them in the event of a full on failure requires the motors being removed and the handbrake wound off (not to hard......if you can get to them so can need wheel removal)
Of course adding things like auto park application etc is just a bit of extra logic in the BCM software.
Moving the Shifter from the centre console to the steering column was when they deleted the mechanical element. It's now a servo that drives the Shift shaft at the box. It's probably quicker and easier to disconnect the propshaft(s).
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It used to piss me off doing MOTs , auto lock this and that when you need to check wheel bearings and turn steering lock to lock jacked up without motor running.
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It used to piss me off doing MOTs , auto lock this and that when you need to check wheel bearings and turn steering lock to lock jacked up without motor running.
But everyone knows, only Mercedes technicians can do an MOT on a Mercedes. Same with BMW, JLR, etc.
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The trick has always been to use the handbrake and slightly apply it for a few seconds when driving at low speed every month or so, this keeps the drum faces clean and helps to stop it seizing up.
Ah, cock, thats the critical bits I missed then....