Brake Pedal Travel.

[Guest]

None engine question so I may get some replies.



Last week I replaced both front calipers, rear wheel cylinders, copper brake pipes and hoses with braided stainless. Before I go looking for a problem how much brake pedal movement should I expect ?. If I pump the pedal a few times to get rid of the vacuum in the servo there is not much travel with the brake pedal, with engine running to get vacuum to the servo the pedal travel is more that I would have expected. There is no “sponginess” when pressing the pedal so I know that I have no air in the system. The rear brakes and handbrake cable are adjusted correctly, this amount of pedal travel was the same before I replaced the above parts. When I was looking at buying a Stag I did notice that all of the ones I looked at had what I would consider more brake pedaltravel than normal but maybe this is how Stag brakes are. It is almost as if when the servo has vacuum it creates excessive brake pedal movement. I know that servos will create more pedal travel but is this normal for a Stag or is there some adjustment or something that I need to do. As advised the pedal is what I would call acceptable when the servo has no vacuum. Am I looking for a problem when there is none ?.



As always and advice, suggestions or comments welcome.



Don Kennedy.

[DJT]

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Hi Don,

I think you have to accept that the design is 40+ years old and not up to the tolerances of modern cars. Having said that, have you checked the clevis pin where the foot pedal attaches to the master cylinder? If this is worn, or a smaller one has been fitted by mistake, this could introduce unnecessaryslack. Also the bushes in the brake pedal pivot can wear. Is there any sideways rockingmovement in the pedal? These are fairly easy to replace (and cheap) but it does involve a bit of grovelling on the floor to drop the shaft out.

Dave

[dogsnadgers]

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After driving a modern I find there is more pedal travel than expected but you soon get usedto it. As long as your brakes are firm and effective I wouldn't worry to much!

Dave

[stustag]

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Hi Don

I have standard brakes with new pads and shoes alround, but have fitted braided hoses this gives me a firmer pedal which travels about a 1/4 of the travel when lightly appllied to 1/3 when pressed really hard.

Stuart

[Guest]

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Hi All,

Many thanks for the replies and suggestions.

The clevis pin and pedal bearings are good.

I realise that the car is 37 years old and the technology is different, just I feel that there could/should be less pedal travel, looks like this is the way Stag brakes are.

Don Kennedy

[Ferds]

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Hi Don,

A couple of years ago, I had my Stag on sa display stand. It was fresh out of the body shop and was looked fantastic.

A guy wandered over and asked me what I thought of the braking system. I told him it was pretty poor - poor braking performance, long pedal travel and it felt like it wasn't going to stop. This was despite the fact it was passing the MOT test every year without problems.:?

He then went on to explain that he was the engineer at Triumph who had actually designed the braking system on the Stag.:shock:

He also added, that at the time, it was one of the best braking systems around, so if it wasn't performing, then there was something wrongin the system.:shock::shock:

We discussed the set up and afterwards I spoke to Tony Hart about getting some work done on the brakes.:?

Okay - in summary, there were various elements that needed addressing.

1) The master cylinder was worn. I found this out when the pedal eventually started sinking to the floor... This was replaced with a re-sleeved item from HRS.

2) The rubber brake hoses were replaced with braided aeroquip types. You do need to do the ones ones that flex for the rear axle movement.

3) The rear brake shoes were replaced and adjusted correctly - so there was only 3 clicks before they came on.

4) New front discs were fitted. The old ones weren't bad, but they weren't 'true' either.

5) Flush and fit new brake fluid.

I've put these in the order that made most difference. My brakes have an near modern feel to them now and the car stops as it should. I don't think there's much room for improvement now.

Hope this helps!

Chris

[Guest]

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Hi, one of our guys has BMW servo and master cylinder, the pedal travel is reduced, but the braking is no better, in truth itdoesn't need to be. These bring their own problems, parts are expensive and not easy to get, and the dipstick has to be heavily modified to remove it without a pantomime. The biggestimprovements I made, were new stainless flexi hoses and Green Stuff pads, I have to agree with everything Chris has said, but as an economic starting point you could do a lot worse. Martin.

[stustag]

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Hi Don

As said by myself and others braided hoses make a huge difference as does new discs,pads,shoes and fluid (which should be change every 2 years).

Also the condition of the suspension will effect braking performance by a considerable margin. Worn dampers, springs and bushes can double the braking distance needed to stop.

I have replaced the whole suspension and braking system on my car and it will stop faster than my Mondeo which is 2 years old and has better pedal feel.

As said above if the whole system is in top order the brakes are really good.

Stuart

[Tdm]

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I have never had a problem with my brakes - in fact they as good & taut (if not better) than any modern car I have driven. My wifes's car is a modern Honda Accord with ABS and all the bells & whistles you get with todays cars, yet my Stag brakes feel better & safer. In 15 years of Stag ownership I have never had a problem with the brakes and haven't touched the original setup in anyway. Mine is a '77 model by the way so maybe they got it just right by then.

[Guest]

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Many thanks for all the suggestions.

I have replaced the hoses with stainless braided. Both calipers and rear wheel cylinders replaced with new ones. Copper pipes replaced. Braking is good but what I was asking was there seemed to be a bit more brake pedal travel than I thought was "normal". If I have any suspicions I would say that the problem is with the servo as if I pump the pedal when the engine is stopped to remove any vacuum the pedal is close to the top of its travel, start the engine to get vacuum and there is more travel than I would expect. I know there will besomepedal travel with the servo working.Looking at the other replies I suspect that I am being to "picky" and am looking for a problem that does not exist.

Don Kennedy

[ethel]

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Don2138 wrote:

I have replaced the hoses with stainless braided. Both calipers and rear wheel cylinders replaced with new ones. Copper pipes replaced. Braking is good but what I was asking was there seemed to be a bit more brake pedal travel than I thought was "normal". If I have any suspicions I would say that the problem is with the servo as if I pump the pedal when the engine is stopped to remove any vacuum the pedal is close to the top of its travel, start the engine to get vacuum and there is more travel than I would expect. I know there will besomepedal travel with the servo working.Looking at the other replies I suspect that I am being to "picky" and am looking for a problem that does not exist.

Don,

did you ever get any improvement on this situation? I've got a very similar situation: replaced hoses, calipers, discs, rear wheel cylinders, pads and shoes, new master cylinder. With engine off the pedal feels fine with what I would judge to be a reasonable amount of travel, when I turn the engine on with the pedal pressed it sinks towards the floor and subsequent brake applications have the same (long) travel. Compared to my (modern) Fiat 500 the extra pedal travel is far greater- on the 500 if I start the engine with the brake pedal pressed then it does move further,but I don't get that 'sinking' feeling. I've done a brief road test and braked from 15-20mph and the stopping was ok (all the junk on the passenger seat ended up in the footwell!), but the pedal was a bit far down when it all happened

If anyone can shed any more light on the subject it would be much appreciated.

Thanks, John.