Handbrake efficiency
Discussion
After owning a Griffith and Chimaera for a long number of years, I have finally got p****d off and decided to do something about the handbrake. I always experience difficulty especially when applying on the brake on an incline as considerable effort is needed. Normal remedy is to leave the car in gear as a safeguard to over come this. I am sure my cars are not the only ones, but if so, perhaps I should start going to the gym!
I see two reasons for this in-efficiency, one being the design of the handbrake lever and the short moment of the cable about the pivot, the second being routing and bends in the cable being too tight causing high friction and loading. Ford did not have a problem so why TVR! Has anyone overcome this by re-routing the cable or other modifications. I would be interested to know before trying to re-invent the wheel. Anyone tried a longer cable?
Any advice will be gratefully received.
I see two reasons for this in-efficiency, one being the design of the handbrake lever and the short moment of the cable about the pivot, the second being routing and bends in the cable being too tight causing high friction and loading. Ford did not have a problem so why TVR! Has anyone overcome this by re-routing the cable or other modifications. I would be interested to know before trying to re-invent the wheel. Anyone tried a longer cable?
Any advice will be gratefully received.
Try just tightening it up a bit... Since I've bought mine I've not been able to get it past 3 clicks even with both hands which at first I thought was annoying but it actually seems to work very well. I use 2 clicks if the road is flat, the full 3 if there is any sort of incline and it's never once tried to roll once on 3 clicks - Not even on a friends very steep driveway overnight (though I was a little nervous leaving it there at first I must say!). I think therefore that you're better off having it a little tight but not worrying about leaving it in gear than having normal movement but no holding power... IMHO of course!
You have to add to this the fact that the TVR handbrake works directly on the disk brakes. Most normal cars have a seperate handbrake brake of some sort. Problem is that you pull up with hot disks, pull on handbrake it grabs a treat and all is fine. Come back an hour later disks have cooled and contracted slightly and the handbrake is no longer grabbing. I learned this the hard way and have a scrape in my bumper to prove it - the car rolled slowly down my sloping drive and scraed down a wall ending up parked across my front door (lucky the handbrake didnt totally give way so it was only a slow roll). Probably made worse for me as I tend to drive and brake hard in the TVR so the discs are always very hot when I pull up and park.
kevin63 said:
Handbrake, where would that be then, I have never had a TVR with one of those.
Well, there is often a little lever type thing, but what it does is anyone's guess....I found that if you bring the lever up high enough to knock your own teeth out with your elbow, that the handbrake worked.. Any lower, not even a sniff of a braking system...
The handbrake mechanism on the calipers are prone to failure. I had the same issue with a Ford Sierra which used the same calipers and when one side failed the efficiency droped right off, as you'd expect. It's easy to diagnose, just lift the rear end any apply the handbrake and check both sides.
The handbrake on my Griff works very well even on a reasonably steep incline.
Colin.
The handbrake on my Griff works very well even on a reasonably steep incline.
Colin.
thenick said:
Try just tightening it up a bit... Since I've bought mine I've not been able to get it past 3 clicks even with both hands which at first I thought was annoying but it actually seems to work very well.
Thats sounds like a surefire way to prevent the ratchet mechanism working?spend said:
thenick said:
Try just tightening it up a bit... Since I've bought mine I've not been able to get it past 3 clicks even with both hands which at first I thought was annoying but it actually seems to work very well.
Thats sounds like a surefire way to prevent the ratchet mechanism working?Edited by fastandcurious on Tuesday 29th April 22:27
spend said:
thenick said:
Try just tightening it up a bit... Since I've bought mine I've not been able to get it past 3 clicks even with both hands which at first I thought was annoying but it actually seems to work very well.
Thats sounds like a surefire way to prevent the ratchet mechanism working?
,the lever on the calipers have to return to the stop on the caliper bodies or the mechanism wont play ball.I find the problem isn’t that the handbrake doesn’t work, but the way it works.
Mine comes up about 3 clicks and there is some resistance to the car moving, but it still moves if you push it or are on a slope.
Four clicks and it has got the car properly. But the amount of force to get that last click is vast. Most people probably couldn’t pull that hard at the required angle.
Somewhere in the back of my mind I recall something that was done on a new car, years ago. But I can’t remember which car.
The handbrake lever came up twice. To apply the handbrake, pull the lever all the way to the top of its travel, (somewhere in the mechanism, a ratchet engages) put the lever back down without releasing the button. Now pull the lever back up. The brake now bites.
Effectively, the mechanism doubled the leverage by halving the movement of the cable for each stroke of the lever.
I wonder if this principle could be adapted to our cars.
Mine comes up about 3 clicks and there is some resistance to the car moving, but it still moves if you push it or are on a slope.
Four clicks and it has got the car properly. But the amount of force to get that last click is vast. Most people probably couldn’t pull that hard at the required angle.
Somewhere in the back of my mind I recall something that was done on a new car, years ago. But I can’t remember which car.
The handbrake lever came up twice. To apply the handbrake, pull the lever all the way to the top of its travel, (somewhere in the mechanism, a ratchet engages) put the lever back down without releasing the button. Now pull the lever back up. The brake now bites.
Effectively, the mechanism doubled the leverage by halving the movement of the cable for each stroke of the lever.
I wonder if this principle could be adapted to our cars.
I tend to agree, the problem is within the lever design due to the package constraints restricting the lever moment. Looking at the car it may be possible to place an additional pivotal lever under the floor between the cable exit point and adjuster. This would effectively change the ratio of movement allowing more leverage to be applied over a longer throw. This would split the cable into 2 sections. I will look at this and other options.
IMO the "problem" is simply the position of the lever. With a normal handbrake you pull it on using your traps and your lats, in our cars you have to use your biceps. Putting your foot on the brake certainly helps, but you just have to give it a bloody good tug to make sure it's all the way on.
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