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Poor brakes and vacuum


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I've now had my car back from the mechanic who was working on it. It's not quite ready for an MOT and there's a lot of jobs left to do before I'd be happy to take it.

 

One thing I've noticed is the brakes aren't anywhere near as good as I was expecting. The mechanic says they won't work at full strength until the vacuum hose is connected to the servo. The brake pedal seems to be where I'd expect and the system seems well-bled. Does the vacuum make a huge difference to the brakes? To give an example, I pushed the car into the garage and had my son pressing the brakes. I could still push it and he said his foot was almost to the boards.

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The vacuum makes a huge difference !

Cheers matey. I've got the vacuum pipe on order so will hopefully sort my fears once I've got it on the car

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The vacuum should not affect the pedal travel to the extent that it would be " to the boards" ? The vacuum servo is to take some of the effort needed to brake , i.e the brakes should still work but with a lot more pressure needed to apply them.

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If your foot goes to the boards then you have air in the system. Without the vacuum connected you should get a very firm pedal with very little travel and you shouldn't be able to move the car by pushing it.

 

Clive beat me to it.

Edited by peejay4A
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The pedal travels only a matter of an inch or so before you get resistance in the pedal but doesn't "pump up" like I'd expect if there was air in the system. It's as though the brakes aren't really there and not stopping the car until you've pressed the pedal almost to the floor.

 

I'll get the vacuum pipe on and see how that pans out. I'm going to go over everything that's been done in any case, for my own piece of mind, so will check it through. This is my first experience with a 6, so I'm not sure what's supposed to feel like what. What I know at the minute is the TR7's brakes were a lot more responsive, and that's sort of what I was expecting

Edited by boogie
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If your foot really travels that far no amount of pumping is going to overcome the problem. Was your sons description a bit liberal? Connecting the vacuum will actually increase pedal travel a bit, not reduce it.

Edited by peejay4A
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Was your sons description a bit liberal?

Possibly, but I don't think he's exaggerated too much. I noticed the brakes weren't very responsive when I was driving it into the garage (before mis-judging how far I'd got left, hence getting him to sit in while I pushed it the rest of the way!!)

 

It's on my list of things to do, so I'll have a good look what's going on with the wheels off

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Tr6 brakes can be tricky to bleed.

 

I’m a convert to the Gunsons Eezi bleed, which works a treat but you do need to ‘convert’ an old tr6 reservoir cap as its an unusual size.

 

Good luck!

 

Steve

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Are the rear brakes adjusted adequately ?? If so then the handbrake should bring it to a halt at "pushing " speed (assuming you are not a super hero of course) so if you could still move it with his foot on the brakes something is wrong other then your query about vacuum.

Edited by Cew
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I have tried all the gizmo's and find the old fashioned method of using two to bleed.One to pump at least five times and keeping pressure on the pedal, then the other one releasing the bleed nipple with pedal pushed to the floor and kept there till the bleed nipple is closed.. Let pedal up and repeat all round. Normaly it does the job, but if not repeat.

 

You have air in the system.

Did you fit new callipers as there is or was a problem with the rubbers seals holding the pistons back giving the symptoms you are experiencing.

Cured by fitting ply blocks half the thickness of the new pads,jaming on the brake pedal with a length of wood and leaving overnight.The rubber seals then get a new memory.

Strange but it defiantly works.

Regards Harry

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Are the rear brakes adjusted adequately ??

I can assure you I'm no super hero!!! I'm going to have a good look around the system then start to tick off each job as I check them out. The rear brake adjustment is one such job. The annoying part is the handbrake raises and just drops back down again so that's another thing to look at and fix as well - albeit a relatively small, simple job (until I find a huge great hulking job as a result of this one!!)

 

Did you fit new callipers as there is or was a problem with the rubbers seals holding the pistons back giving the symptoms you are experiencing.

The whole brake pipes have been replaced, so I'm going to check they're all running where they should. The calipers are stainless steel ones with new seals fitted. The pads were bought to fit the SS calipers. Again, I'm going to check all of this through as part of my full review of works carried out by the mechanic.

 

I suppose what I was trying to establish - which you've all confirmed to me - is whether the vacuum advance makes a huge difference to the braking. I suspect the lack of braking power lies elsewhere and isn't just the fact the vacuum hose isn't fitted (yet).

 

Thanks all, I'll keep the thread updated once I've got to the root cause.

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The dual circuit system can be awkward to bleed if bleeding has been done with a vacuum bleeder, it tends to remove all the fluid from the second stage (smaller reservoir in front of the main one on the master cylinder) that might give you a firm pedal but only braking on two wheels .

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I've checked all the pipework through and it's all going from and to the right places, so one potential removed. I'm going to start looking into the operation of the brakes when I can get the car out on the drive and get all around it without getting wet (is Summer really over now?).

 

I need to overcome another issue with my seats before I can look at the handbrake so I dare jack the car up once it's on the drive. I'll post the seat issue on another thread to avoid going off-topic

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