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MG MGB Technical - Front Brake Hose Length

I can't remember if I've asked this before, but this has been bothering me for some years.

In 1996 I found that I needed to replace front brake hoses on my 1967 Mk1 B, as the N/S was collapsing internally.

I bought some replacements from, what was then, Moss Birmingham. When fitted, they seemed to be straining on full lock. When I compared them to my old hoses, I found that the new ones were shorter.

I had no reason to believe that the hoses that I removed weren't original, as they looked very old, were idential, the car had relatively low mileage and had a sheltered life!

When I asked Moss, they confirmed that what they had supplied were the correct items for a chrome-bumper model. I also checked with Leacy and they said the same thing.

I took my old hoses to a local brake specialist (who have long since ceased trading) who managed to find me a pair of identical hoses. From memory, they were from either a BMC JU250 or EA350 van.

It has now come to the point where I probably need to replace them again and I am obviously facing the same problem.

Although all the usual suspects only list one brake hose for the chrome-bumper model (GBH158) and another for rubber-bumpers (GBH172), the MGOC reprint of the factory parts book lists another - GBH109 - which it says "use prior to GBH158", although no change point is given.

The only reason I can see that there would be for a longer hose, is if the bracket on the crossmember was in a different position.

Does anyone happen to have a GBH158 hose to hand and could measure the length between the two ferrule flanges?

I have roughly measured mine, although it is still fitted to the car at the moment, so might not be exact.



Dave O'Neill 2

Here's a pic of the currently fitted hose on full lock. It also shows the crossmember mounting bracket.


Dave O'Neill 2

My original Leyland Parts Catalogue lists GBH109 for CB with the remark 'Use GBH158'. Then complicates matters by listing them on a second page saying 'Use prior to GBH158' but for chassis number up to 394300 i.e. into the RB period, until armoured hoses GBH172 were used from December 1975.

Nearest I can measure on-car flange to flange is 321mm so quite a bit shorter than yours, but still plenty of curve (full lock) as in the attached.

This page https://www.dormanproducts.com/p-29527-h36903.aspx quotes the overall length as 362mm and shows GBH109 as equivalent to GBH158.



paulh4

Position of bracket relative to damper.

Easier to get to the off-side with mine.


paulh4

Sometime back there was adiscussion on the length of the ss braided hoses supplied today for use on a BGTV8 on the V8 Register forum/website.
May give a clue tothe length of hose required.
G R Wilder

http://www.v8register.net/FilesV8WN/140822-flexible-front-brake-hose-check-MGB-MGBGTV8-BJ2.pdf

That's very tight. I have braided on the V8 (attached) and whilst they are maybe 9-10mm longer hex face to hex face the metal ends are significantly longer than on the rubber ones, which is probably why that hose is a bit tighter. These ends are 33mm long each, whereas on the rubber hose they are 22mm and 25mm.

You need to check both sides, or compare the turns from straight-ahead to each lock, in case that is unbalanced which will make one side tighter than the other.



paulh4

when I changed the front hoses on my car (1969 MY) I fitted Delphi ones part no LH1737, correct length, and good quality.
Andy Tilney

From Clausager: The hoses changed to anti-torsion on the V8 in May 74 i.e. CB, but didn't change on the 4-cylinder until May 75 i.e. RB. If this is the earlier change in the Parts Catalogue, then both GBH158 and GBH172 are suitable for all years and applications, and the armoured hose probably preferable.
paulh4

"You need to check both sides, or compare the turns from straight-ahead to each lock, in case that is unbalanced which will make one side tighter than the other"

That doesn't explain why the original hoses were longer.

A bit of a long shot, I know, but does anyone have a Lockheed brake catalogue from the mid '60s?

I'd like to find the Lockheed part number for the early front brake hose, and any specs that may be in there.
Dave O'Neill 2

Indeed not, but neither does it explain why the shorter hoses seem to be OK on mine, for example. How many turns lock to lock do you have?
paulh4

Funnily enough, checked mine recently, because I'm going to overhaul my 4 pot system. '72 Roadster with neg camber wishbones. Measured braided ones I had on the original calipers, and ones I'd had made for the 4 pot system: both 34cm long from nut flange to equiv other end (as per diagram in OP). When fitting it's important to get 'set' right ie twist, or lack of. I found with mine if wrong, they caught up on lower wishbone.
Peter Allen

“neither does it explain why the shorter hoses seem to be OK on mine, for example.”

Which is why I’m trying to establish the specs for the ‘no longer listed’ hose and, if possible, the change point.

“How many turns lock to lock do you have?”

It’s just shy of 1.5 turns each way. I can’t quite believe that the B doesn’t have any positive stops on the kingpin, as the midget does, to limit travel.
Dave O'Neill 2

Same as mine, is it the same both sides? Both mine are offset slightly, to opposite sides, but in both cases the hoses are long enough.
paulh4

Pretty much the same. Less than 10° difference at the steering wheel, I would estimate.

I think I may have now tracked down some hoses, identical to the ones currently fitted. My local motor factors - PCS in Clay Cross, near Chesterfield - had a look through their 'Brake Engineering' catalogue and came up with a hose which is 346mm long with the same ends.

The application is Triumph Stag front, or Bedford CF rear, apparently.

Having googled 'Triumph Stag front brake hose', I have a list of alternative part numbers:-

Unipart - GBH211
TRW - PHC228
LDV/Rover - 37H8803
Delphi - LH1734

the latter being very similar to the number on the receipt that I found for the current hoses - HAP 1734 - from the now defunct Brake and Clutch Components of Acocks Green.

I should be picking some up this afternoon, hopefully.

However, I would still be interested in knowing the length of a GBH109 hose, as well as finding out whether any other owners of Mk1 Bs have an issue.
Dave O'Neill 2

This thread was discussed between 07/07/2019 and 23/07/2019

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