brakes rules

[Tmoose]

Parker A-LOK compression fittings are claimed to seal at the pressures that might be found in a hydraulic brake system.
I'm thinking there may be some specific statements in SAE or DOT rules/standards/guidelines that disqualify anything but double flare or metal gasketed joints.

Does anyone know a good reference?

thanks

Dan T

 

[GregLocock]

Won't be in SAE as they tend to be descriptive rather than prescriptive.


Cheers

Greg Locock


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[swall]

Even if SAE specs and FMVSS are silent on this, there may be restrictions in the motor vehicle safety codes of some states (like Pennsylvania).

 

[evelrod]

I thought I had access to a fairly large amt of information on brakes and braking systems as related to automobiles...specifically, race cars. I've looked in most of it and, so far, found all sort of specs for tubing, hose, fittings (SAE and AN)...Nothing in the California vehicle code aside prop 65 restrictions on the brake material...Nothing explicitly addressing "double flare" or whatever.
I'm pretty sure I have seen something, but ??? We all know how to do it, just nothing in print, not even in the SCCA GCR.

I have some brake tubing flare tools (Imperial and US spec) that have instructions for varying makes of car, etc. I've seen catalogs from parts mfgrs that make similar claims as you have...just nothing official. Perhaps someone has access to OEM specs?

Rod

 

[Tmoose]

I was surprised that when asked Parker tech support about suitability for car brakes, they sent me a spec sheet. I'm pretty sure there is more to it than that. If a shop made a brake repair with compression fittings the deceased's family would have it made.

 

[rmw]

Some of what is done in the automotive world is less about codes and standards and more about how fast, simply, and repeatably parts can be assembled onto autos moving down an assembly line.

I don't know if that is relevant here; I'm just saying.....

rmw

 

[Tmoose]

(reproduction) 1948 Chevy truck factory shop manual re: hydraulic brake tubing.
"This safety steel tubing must be double lap flared at the ends in order to produce a strong leak-proof joint."

The exact same wording is used in the 1965 Corvair Chassis shop manual and the 1972 Chevrolet Passenger car Service Manual.

 

[MikeHalloran]

Compression fittings were developed for tubing with a solid, one-piece wall. No one has experience using them with double-wall brake tubing because they're more expensive than inverted tube nuts on a double flare, which has been shown to work just fine for decades.

They might work fine, or they might induce some odd failure mode in the tubing, or fail themselves in some odd way because of the tubing's unusual nature.

Why bother?



Mike Halloran
Pembroke Pines, FL, USA

 

[Tmoose]

Hi Mike,
I wasn't aware 3/16" brake tubing is double wall.

On some car list someone posted they've been using the A-Loks at work in high pressure apps, so started using them on his car. I didn't and don't think that's right, so I contacted Parker tech support, expecting them to squelch the idea, in preparation to alerting folks it might not be a real good thing to do. So far I have nothing. I'll be Off to the UMass Lowell tech library for research on that and a few cracked gear topics.

 

[evelrod]

I'll go back to your original point, Dan. I find it pretty strange that I cannot find any "rules" pertaining to the compression fittings/automotive brake use. For me, I used the compression fittings all the time...in air lines, low pressure water/hydraulic lines in my brief career as a industrial air compressor tech. ('98-'02) They worked fine on tubing, even plastic tubing.

On one note, I did see compression fittings used on the hydraulic brakes of a go kart...

I agree, Mike...why bother? The US double flare, the AN 37 degree tapered, the Imperial "bubble flare" work just fine...again, why bother to "re invent the wheel"?

Rod

 

[swall]

As one who has struggled trying to make brake tubing double flares with a $49.95 flaring tool, I can see why someone might be tempted to take a short cut via the compression fitting.

 

[Tmoose]

"On one note, I did see compression fittings used on the hydraulic brakes of a go kart..."

I seem to recall a friend's racing kart used nylon tubing, at least for a spell back in somewhat less litigious times. I never worked out the attainable pressures, but That suggested to me the pressures were less than the 1000 psi plus in car brakes. Also, that concerns about the plastic tubing being abraded or otherwise damaged were not considered important.

 

[patprimmer]

I think engine braking on a go cart is significantly greater than on a car and they only normally have rear brakes so brakes are not real effective, therefore the difference in braking from a line failure is not nearly as great as in a car.

Also line pressure in a cart might be lot lower.

Regards
Pat
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[evelrod]

You have not been to a go kart race lately, eh?

250cc, six speed, 3 disc brakes (solid axle at rear with only one disc)...

A bit aggressive on acceleration and braking would be an understatement!!

I wish I were not so old and "fragile"! ;o(

Rod

 

[dbecker]

Nylon on the brake line? Even if it could hold the pressure wouldnt the line expand and make the brake feel mushy, thats the first time i heard of that being used. Was the nylon in a braided stainless sheath or something?

 

[evelrod]

No. The carts I helped with had nylon tubing also. Actually, since it was just a kart, I never really thought much about it. I was just there to help one of my co-driver's son race. I'm not a kart racer.

http://www.sunlpartsonline.com/carter-go-kart-brake-set-10-5523005-p-12754.html?page=9

http://www.zoomkarts.com/product.asp?productID=77

I simply hit 'go kart' and ended up with this. I talked to Don about his kart and he said the brakes were Airhart, just a single rear disc on his cart, though.

Rod

 

[rmw]

I went on a "teambuilding" event from work a couple of weeks ago and it was Go Kart Racing. There was no engine braking that I could detect on those things. They were blazingly fast. This geezer showed those kids what true competition was all about. I came in second in the final starting from 4th of 8 positions after coming in second in all 3 qualifying heats, but I digress.

Point was, I used all the brakes those things had, and it often wasn't enough. Had to use the 'driving sideways' skills I honed when I WAS a kid driving my dune buggy. I wasn't afraid to throw it into a skid.

It was, however, the most fun this old man has had in a very long time. Those younger guys just weren't ready for my driving style.

Back to the topic, I never did bother to look at what material the brake lines were, but I did use all the brakes that it had.

rmw

PS: afterward we played laser tag and I won both of those. But I guess that is off topic.

 

[drwebb]

Racing karts are often 2T, which generally have less engine braking than 4T engines that are usually fitted to recreational karts.

 

[drwebb]

. . . oh yeah, but rec. karts usually have centrifugal clutches, so no engine braking there anyways . . . nevermind.

 

[stimpy1966]

have you checked DOT CFR49 for the regulations?? as they will cover specifics on braking sytems

go broke try to go 150 mph and if it will fit drop it in, if it dont get a plasma cutterand the welder