Goodridge Brake Hoses

"Jason Russell" wrote in news: snipped-for-privacy@pipex.net:

I've only ever had them made up for the bike, but they never caused any trouble, a lot firmer than the ballooning stuff they replaced. Never discoloured or rusted either.

Don't go with Aeroquip, get them ready made-up from Moquip (ads in the back of the car mags). They do a very similar braided hose, with the addition of a clear PVC oversleeve.

Braided brake hoses work well but they are a serious longevity problem. There's a lot of ways to damage them and if you're going to fit them, then you need to inspect them regularly too. The clear oversleeve is a big help in doing this.

I have Goodridges on my Celica. Work really well, much firmer and better feel.

I disagree - braided hoses far surpass the rubber hoses in all the relevant fatigue/whip/impact tests. Although i agree the sleeve makes a difference. The only time you'll have problems is if you have bought low quality ones and they require twisting to fit OEM fitting positions etc. A lot of people who have had problems have eventually tracked them down to poor assembly.

J

Got any evidence for that? Braided PTFE brake hoses (on most cars) aren't even road legal in Europe and there's no inclination to make them so, because of PTFE's cold flow behaviour. You get a minor impact or kink into the inner liner and the hose _will_ fail at some future point, unless you catch it by inspection first.

If you can feel any difference in braking on a road car with a brake servo, then your old hoses must have been f@=A3ked to begin with.

I use braided PTFE hoses on old cars where I can't source the original pattern easily, but I'm in no hurry to fit them on my daily driver.

Wheres the law regarding legality? And since they've been used on motorbikes as standard equipment for many years, which are more susceptible to impact damage and kinking, i cant see how its more likely to fail personally. I cant see how i'd get an impact on my hoses anyhow, they arent exactly in a very impactable place.

(internal) report on hose lifespan. Ive never yet heard of the ptfe liner failing, only the exterior pulling away from the end connectors in cheap versions or those badly assembled.

Thats your call, doesnt make it right. I fitted them to mine after I found toyota wanted over =A3175 a set for them and no-one made copies apart from goodridge.

Type approval. Non OEM PTFE hoses aren't (as they're not standard fit on almost anything).

They're also a lot easier to inspect.

Then talk to anyone connected with rallying.

AFAIAA That doesnt make them illegal, only not fittable as OEM, and there are OEM cars that use braided hoses - many modern cars such as Porsches have them, unless all the ones ive seen in passing have been modified - which seems unlikely.

Very true, i admit that.

I do, regularly, being the owner of a rally homologation car and a member of the owners clubs I speak to people who actually rally and track them on a regular basis and do professional full car rally re-fits. Ive yet to meet one that didnt agree with braided hoses and fit them to normal daily drivers. Maybe all of my contacts are wrong, who knows.

J

Fit them by all means. But if you do, inspect them regularly. PTFE cold-flows. Kinks turn into holes.

Well thanks for the warning, I will indeed inspect mine regularly now you've brought this to my attention - cant be too careful! I'm curious though, the only references to this behaviour that I've found have been things you have written - i am assuming this is an aknowledged problem that seems to have been overlooked by my contacts - but im obviously searching under the wrong keywords - any chance of a few links on the subject?

I think I'd struggle to kink the goodridges - they're very solid - the outer sleeve gives it even more solidity so its only if you kink it at the junctions that i can see this occuring?

Cheers J

Numero uno: "Unfilled PTFE has the following, more or less adverse properties: * Cold flow behavior "

I know, i found that link also but:

A) Thats "unfilled" - i.e. its pure PTFE - I would suspect the makers of the PTFE hose would have used one of many available additives to reduce/eliminate the cold flow behaviour. Much like the epoxy resin around kevlar fibres is brittle and shatters easily in pure form, when combined with the fibres you vastly increase its ductility and impact absorbtion ability.

"Cold Flow Behavior

When subjected to constant tensile stress or pressure loads, PTFE will already escape, i.e. flow, at room temperatures. This behavior is contingent upon the pressure or tensile stress exerted, the duration of this stress as well as temperature. Due to these properties, PTFE parts subjected to higher levels of mechanical stress are either encapsulated, thus preventing their escape, or PTFE compounds with clearly enhanced pressure resistance properties will be chosen."

I.E. the compouds can be manufactered to reduce this easily. Either way it would require a hole in the braided encapsulation to flow, which is fairly hard to achieve in the tight-weave braided stainless of goodridge hoses.

B) Theres no links to this causing problems on vehicles. Not one that i can find in 30 mins of lunchtime browsing and googling. I have, however, found MANY links to factory bikes and cars that have braided lines as standard.

Sure the PTFE hose is weak on its own in comparison with rubber, despite whatever fillers are used to adapt its characteristics, but it has a very very tough encapsulation of braided stainless wire. I have to point out that the rubber hoses used now are a rubber>braided fabric>thin rubber sandwich, and if you happen to wear through the braided fabric layer (fairly easy with a badly aligned part, ive had it happen) the inner rubber layer goes POP with surprisingly little pedal force. Its very similar in principle except its a damn sight harder to wear through or slice a plastic coated, stainless braided encapsulation than it is a rubber and fabric one.

And incidentally the Goodridge hoses fitted to my car are DOT/TUV approved, so i'd assume most are.

J