HR Rear Backing plates - there is a difference

[reddo]

Hi All

I thought i would stick this ëxperience"on the forum so that no one makes the mstake i did.
Its a bit long winded but it might save someone the bullshit i have been through getting the disc brake conversion right on my van.

Some time back i converted the FB van to HR front end HR rear end... boosted drums on each corner.

Here comes ....Mistake number 1..
i used a HR Ute as the donor vehicle. HR commercial ( van and ute ) have wider brake shoes than the sedans.
Good i thought... more swept area in the drums equals better stopping.
at the time i ordered a new handbrake cable to suit HR to FB conversion....

I went to fit it and found ..
Mistake number 2......the outer sheath on the handbrake cable pulled up about 40mm short of where the FB outer clamped up on the chassis?? Odd i thought... never mind i will just make a flatbar with 2 holes so i can bolt to the original bolt up point and then clamp the ute 40mm further back at the other hole... problem solved.
The whole time i drove around like this the inner cable seemed "compressed " from entry in the backing plate to the plate that clamps to the rear shoe.. mistake number 3.. never mind the handbrake works fine??

Over christmas i ditched the drums and fitted the new discs.. rotors.. calipers... swapped the old drum booster up the front for the disc brake booster. New narrower shoes with different cutaways compatible with the disc front end and smaller diameter wheel cylinders in the rear to suit the different shoes..
All seemed to fit up good and the brakes worked fine... except the shoes didnt seem to sit in the centre of the wheel cylinder pistons.... mistake number.. 4 .

After towing the vintage van to Cowra and back the other week up and down steep hils i could smell brakes cooking????
The fronts where working a lot harder than the 60/40 split i thought the brakes would have.??

So... on to today.
I thought i would have a poke about and see what was going on with the stoppers.

Pulled the rears completely to pieces. all looked good....
Then i dragged out a set of rear brakes i pulled off a HR sedan i wrecked a while back.....

Then it all hit me... the sedan backing plate is completey different to the commercial plate..
see pictures..
.http://i10.photobucket.com/albums/a150/ ... CN0169.jpg

left is HR commercial.. right is HR sedan


The differences.
1... hole in plate for handbrake cable is closer to the centre of the backing plate by 40mm ( hence mistake number 1)
2. ..The raised "Horseshoe "shaped section pressed into the backing plate on the sedan plate is about 12 mm higher than the commercial so it supports the thinner shoes ( see mistake number 4)

The van plate
http://i10.photobucket.com/albums/a150/ ... CN0171.jpg
the sedan plate..
http://i10.photobucket.com/albums/a150/ ... CN0170.jpg

3.... The top half of the sedan backing plate "rolled edge "is non existant
4... the van backing plate has a vertical "metal tube"welded in the centre at the bottom... this meant that the inner cable and return spring had to drag over it to reach the handbrake lever that rivets to the rear shoe... ( see mistake number 3 )

Once i finshed slapping myself about it took less than an hour to fit up the sedan backing plates and reassemble the drums.. the shoes now sit in the middle of the brake cylinder pistons.... something they had never done before..causing the shoes to expand on an angle rather than square out from the cylinder piston.... not much chance of a 60/40 braking effort while that cock up was happening in the drum..

The brake cable sits neatly in the backing plate.
and everything fits as it should.

Still gotta remove the botched up outer cable retainers up on the chassis rails either side and readjust the handbrake cable now that i have found another 40mm of cable on ether side

Root cause of all the problems??
Using commercial backing plates off the donor ute in the first place instead of sedan backing plates....sure it gave me wider brake shoes ... but i inherited a whole stack of other "issues"further down the track..

I know the question still remains..
What did GMH fit to the HR utes and vans that where special order with disc brakes??
After the shitfight i have been through over the passed couple of years... up until today ,
I can only suggest that they had to fit sedan backing plates ... the correct small cylinders and shoes .and maybe a sedan h/brake cable???

Regards
Reddo

[wot179]

Why didnt you just fit commercial brake shoes?

Did you remove the relief valve in the master when you fitted the discs?

[reddo]

Why didnt you just fit commercial brake shoes?

Did you remove the relief valve in the master when you fitted the discs?

answer to the first bit... the rear brake shoes that are compatible with a disc brake front end are narrower... a
The rear wheel cylinders that are compatible with a disc brake front end have a smaller bore to help proportion the braking effort more equally...
They also do not use the short rods that stick out of a normal wheel cyliner into the shoes. The ends of the cylinders push directly on the shoe.. which does not have a cut away in them to take the rods.

Totally different to HR commercial shoes .. which are wider than standard shoes and use a different ( bigger bore) brake cylinder to the smaller disc brake compatible rear cylinder... search on ebay .. you will find the rear shoes and cylinders to suit the rear of a car with disc brakes on the front.
I know it flys in the face of what you think would be better.. nice wide shoes with bigger cylinders and drums ... but it is done for a reason.
I bet there is a lot of disc brake conversions running around out there still using the standard HR rear shoes and wheel cylinders or the comercial rear shoes , drums and cylinders and not getting the full benefit of a proper GMH designed disc / drum set up.

Have heard of people welding a nut into the standard shoes so the smaller cylinder piston pushes directly on the shoe .. no need for the clyinder push rods. That would work on sedan shoes with sedan backing plates.. but not on commercial shoes as already proven.. the shoe doesnt sit centre on the cylinder piston...because of the different offset in the backing plates.

The alternative to the GMH set up is to fit a proprtioning valve in the brake line pipe.This would cost ya a couple of hundred to buy and fit... a set of proper rear shoes and cylinders to suit disc fronts is around $70 on ebay.

Also... the commerical drums are around 68mm deep and the sedans are around 58mm deep.
Ya cant use commercial drums with sedan backing plates..
ya can see the difference in the following photo. commercial on the right.. sedan on the left.
http://i10.photobucket.com/albums/a150/ ... CN0172.jpg
and the shoes...
commercial on the left ....sedan on the right
http://i10.photobucket.com/albums/a150/ ... 0527-1.jpg


Answer to the second question....
The restrictor valve was removed from the master cyl when i fitted the rotors/discs etc about 5 months ago..... if i hadnt removed the restrictor from the master the disc brakes would have come on and stayed on after i took my foot off the brake.. they do release eventually but drag for a for while once you take your foot off the brake. and cause the brakes to heat up... Removing the restrictor was one of the first things i done when converting from drums to discs.

'Spose all i am trying to warn people about is ..
HR commercial drums .. shoes and backing plates are the go if ya want good drum brakes especially with a booster.
... i towed my caravan ( has brakes) with that set up on the panelvan for a few years.. great .. until you get a long down hill stretch and the brakes start to fade...

Disc brakes are better stoppers than drums .. especially if you have just driven through water etc. and .. definitely better than drums for pulling up when towing a caravan or a loaded trailer down a steep hill for a few kilometres.....

just dont leave the commercial backing plates on if you convert over to a disc brake front end...do the job properly .

Regards
Reddo

[Dr Terry]

Hi Guys.

There ARE unique shoes which fit HD/HR ute & van with discs at the front.

The narrow (sedan/wagon) shoes are 1 1/4-inches wide, while the wider (ute/van) shoes are 1 3/4-inches wide. 1/2-inch extra.

The industry part numbers for the narrow shoes are E1174 to suit 4-wheel drum cars & E1132 for disc braked cars.

The numbers for the wide (commercial) shoes are E1172 to suit 4-wheel drum cars & E1130 for disc braked cars.

E1172 are also the front shoes for all HD/HR 4-wheel drum braked cars. Interestingly 1965 production EH ute & van also use these wide brakes all round (4-wheel drum only).

To identify the both versions of the disc brake type shoes at a glance they have no cut-out for the wheel cylinder pushrods.

E1130 shoes are so rare that many so called brake specialists deny their existence. Many catalogues no longer list them.

Dr Terry

[rosco]

Reddo,
I'm having shades of deja-vu here.... In 1982, I fitted a disc front end to my old bus - but it was later found very much different to just about everyone else's..... mine, in fact IS a HD disc front end - at the very end of production of the HD - when HR's were beginning to roll - some HD's were released with disc fronts, HR "disc brake" rears and the Girling booster.... not many know that the upper wishbones of HD's differ to that of HR's...

Now, to the rear shoes - I went to the wrecker and picked up a full set of HR disc compatable rear assemblies - and fitted them to the EH rear diff I had - yes, the insides will bolt on inside the EH backing plates. I fought the handbrake issue for fifteen years - until I had a cable made up to suit the EK front, length required and the HR disc rear drum brake assemblies.

Those master cylinders you mention are 9/16" bore - you can barely get your little finger into them. They also have "button" ended pistons - which of course fit into special shoes..... I believe they did this to prevent the wrong wheel cylinders and shoes being fitted to a disc brake front end...... for Holden, this was cutting edge in 1966 with the HR (it was a particularly bad vehicle for handling)....... along with the many, combinations of "special vehicles" they tried - X2, 4 speed (Opel), and finally 186S (with silver coloured air cleaner - not the latter gold in later models). When the HK came out - there were even more options... but, as one F....D enthusiast mentions to me often in debate - if you wanted, you could get a 327 cu in engine, a "crunch" box and drum brakes...... can you imagine the combination....?

In answer to your observation on braking efficiency - I have always voiced the opinion that drum brakes are more effective than the dsic front many conceive they fit for greater braking - sadly, this is not what I have found. If the same booster were fitted to the drum brake front end - you would probalby be well advised to ensure your seat belt is adjusted up tight...... they "grab" far greater than the discs..... this was the first lesson I learned...

But, as for efficiency, ease of replacing pads and more resilience to fading if callled upon on successive - or as you tow.... a greater demand - the discs option far out-perform the front drum brake system... this is my firm belief - and what I have found in my experience.

As for shoes - if it were possible to fit the 9/16" smaller wheel cylinders to standard rear shoes - I don't believe there would be a noticeable difference - the same amount of force is being applied to the shoes - BUT - the shoes would last longer due to the greater working surface...... there is a big difference between force and braking area.... which I recall was often mentioned when comparing braking aread between vehicles,

We need perhaps to look at master cylinder vs wheel cylinder. It's the "ratio" which does the work.
A 1" master cylinder acting on a 3/4" wheel cylinder will exert more "work" to the shoes - than the same 1" master cylinder acting on a 9/16" disc compatable wheel cylinder. Initially, we believe the opposite - as in what most conceive is a greater volume - but this is not the case - it's the "leverage". I can only suggest that if the same 1" master cylinder was acting on a 2" slave cylinder - the power transmitted would be exceptional - but the brake pedal would almost go to the floor to achieve it.......we must remember, force not volume.......
If we were to use the standard front drum brake compatable rear wheel cylinders when setting up a disc front end - the rear brakes would almost lock up on each application. To add a power booster to this would make it very difficult to avoid as there is precious little pedal travel when using the hydraulic servo-boosted system.

Many decided long ago to ditch the entire small wheel cylinders and either use a proportioning valve OR to fit a later model firewall mechanical operated booster which afforded correct (almost) proportioning by the difference in size of pistons - larger for front, smaller for rear...... AND which of course - afforded the secondary system dual circuit should one fail.....

So, in answer to this - the only two advantages I can forsee with running the larger shoes/drums and going to the extreme to make them compatible with the smaller wheel cylinders - are 1/ more working surface - less wear and 2/ a better "grip" using the handbrake.

It is a timely warning - for those who run standard, run a single line disc/drum brake conversion - that "if" any component in your system develops a leak - you will lose all hydralic braking - and will be lef to stop the vehicle by gears and handbrake.......

frats,
Rosco

[Dr Terry]

Good points rosco, although I'll pick you up on two points.

You state " When the HK came out - there were even more options... but, as one F....D enthusiast mentions to me often in debate - if you wanted, you could get a 327 cu in engine, a "crunch" box and drum brakes...... can you imagine the combination....?"

The 327 was unique to the GTS 327 model & not on the options list. The 'crunch box' was only fitted behind 6-cyl engines. But what you say was almost correct. As I understand if you multiply the models by the number of available colours & trims & then factored in the engine/gearbox/diff options & finally things like power drums & power discs, power windows & tailgate, air cond & dozens of minor options, the number of available HK permutations was around 2 million. I've seen some terrible variations, like a 307 Kingswood wagon with power windows, air cond & 4-wheel drum brakes, it was painted an awful pale green with red interior trim & bench seats. In early HK, if you ordered air cond on a 307 V8 you couldn't option disc brakes. Yes, an air cond V8 with 4-wheel drums, nice !!

Your point on the wider rear shoes is almost there, the wider shoes are for stopping a heavier load, hence their use on the rear commercials. They simply have more stopping power even though, as you say, the pedal effort will be higher.

HD discs weren't introduced at the end of HD production, they were introduced around 4 months from the beginning of production. Early HDs had a kingpin front end similar to EJ/EH, with drum brakes the only type available. All HDs from 1/6/65 got a new design ball-joint suspension as standard (with drums) & front disc brakes available as an option. HDs with front discs brakes had the small 9/16-inch rear cylinder as per HRs. HK/T/G & LC/LJ Toranas with front discs also had these small rear cylinders. The booster to the HD (with discs) fitted was the Girling Powerstop 5/8-inch unit. This set-up was carried over to HR with slightly altered top & bottom wishbones, resulting in altered front wheel alignment. The Girling booster stayed in production thru HR until it was superseded by the PBR VH40 in April 1967, meaning there were more HR disc-braked cars with Girling boosters than the PBR item. There are also more HDs with HR style ball-joint front ends than the kingpin style. HD commercials were released after the ball-joint front meaning none were produced with kingpins.

Dr Terry.

[reddo]

Thanks for the input guys.....

I got into a "debate"a few eeks back when i told a bloke that HD and HRs had different top wishbones.
He said i was a nutcase......I was beginning to doubt myself as i was told this many years ago by a mechanic who lived and breathed Holdens.

My first registered car at the age of 16 y 6 months was an early 1965 HD Holden panelvan.... with a Kingpin front end.

When i done the HR commercial drums ( and backing plates ) conversion on the FBvan i ordered a cable to suit FB with HR rear end. The outer sheath pulled up 40mm short of the retainer clamp... as stated before i rangthe supplier and complained.. he siad my car must be bent...
3 years down the track and i find the HR sedan backing plate has the hole 40mm further towards the front of the backing plate...bit late to riung and apologise.

Havng towed the old vintage van on many occassions i will admit that the HR commercial drums all round are a better set up in a one off rapid stop situation. i have had a couple of bad experiences with the discs locking up when pulling up at roundabouts in a hurry etc, etc. It feels like the rears are doing nothing??. i have taken my foot off the brakes and taken a second stab thinking they might need pumping a bit... but .. no.. same result... front end lock up and lotsa blue smoke.
I have adjusted the caravan cable brake set up to a point where the brakes are just about on when sitting still..... so the van is doing its job.. but the discs are taking a lot of the load in an quick stop.

Cant help thinking about the load it must be putting on things like the upper and lower control arm nuts.. top and bottom ball joints and the caliper mount bolts when the front locks up like that...

Only other thing i think i can do to get a bit better split on the braking of the car when towing is to fit load levellers... i hate the fn things...

Happy enough with the way its pulling up without the van on... maybe that proportioning valve for around $260 fitted at a brake shop might be the go.... or.. tear the master off and fit a HK/t/G firewall mounted dual circ master with booster.

Anyway guys thanks for the interest in my original post. i have learnt something... and aint that what the forum is all about

Reddo

[Errol62]

I’m going to reignite this old thread I think. I am installing an LC LJ rear axle under my ute. It has what I believe to be HR commercial rear brakes. The linings are 1 3/4” but the drum machined surface is more like 2” wide. The outer edge on the drums actually stick out beyond the mounting flange. Handbrake cable mounting seems to be conventional from my experience snd I don’t have any of the issues experienced by reidy back in 2006.

Curious thing is that the shoes have been modified to suit the disc style wheel cylinders, by simply filling in the rod slot with weld. Purchased new wheel cylinders, and the shoes and drums are virtually as new spec wise. The cable is a custom HR into FB one from retro spares auto cables.

[Blacky]

Its been over a decade since I did mine, I cant recall having any problems, just recoed the Torana stuff and ordered a handbrake cable and it all went together nicely as I (dimly) recall ???

[Errol62]

Some photos

FB ute driver, EK van project

[Errol62]

Yeh blacky was told the brakes are HR commercial not LC LJ. May well be the same for all I know. In any case if the shoes are only 44mm (1 3/4”) then passenger car are narrower. 1 1/4” according to Gregory’s. When I lodged my request to fit the 179, road traffic stated 44mm wide shoes required front and rear, though only duo servo self energising on the front. If I had fitted sedan brakes I would have failed this requirement wtf! What they are specifying is effectively leave original brakes on rear and just fit EJ HR front. This could be achieved using EJ stub axles I think, resulting in minimal modification. I am just fitting the discs because they are lying around gathering overspray.


FB ute fixer upper, EK van on rotisserie

[Errol62]

Why did GMH go from 1 3/4” rear linings on FB EK back to 1 1/4” on EJ? Possibly trying to solve rear lock up tendency.


FB ute fixer upper, EK van on rotisserie

[ardiesse]

Clay,

I've only just seen the thread.

Gregory's is not a definitive source of information. And here, they got it wrong. EJ and EH had 1-3/4" wide shoes front and rear. Your master parts cattledog will hopefully list the one part number for EJ/EH (passenger) brake drums. And yes, the machined inner surface of drums for 1-3/4" brakes will be closer to 2" wide.

Do you have steel rules graduated in proper units? 2-1/4" is 51 + 6, 57 mm; 1-3/4" is 51 - 6, 45 (+or- 1) mm.

The reading for today is taken from the 1984 Repco catalogue, chapter 7, pages 985 to 986.

EJ and EH passenger vehicles take E1174 shoes front and rear.
EH commercials with wide brakes, HD and HR commercials with front drums take E1172SA shoes front and rear.
HD and HR passenger vehicles with front drums take E1172SA shoes front, E1174SA shoes rear.
HD and HR passenger vehicles with front discs take E1132SA shoes rear.
HD and HR commercials with front discs take E1130SA shoes rear.

From which I infer that the SA suffix means "self-adjusting", and that a design change was made to accommodate the self-adjusters. Also, EH commercials with 2-1/4" brakes had self-adjusters.

Six-cylinder LC and LJ Toranas with front drums take E1174SA shoes front and rear.
Six-cylinder LC and LJ Toranas with front discs take E1132SA shoes rear.

Here endeth the lesson.

1174SA brake shoes are 1-3/4" wide, and suit EJ, EH (front and rear up to Mar '65), HD, HR (passenger, rear, 4-wheel drums), LC and LJ 6-cyl. (front and rear,4-wheel drums).
1132SA shoes are 1-3/4" wide with extended webbing for 9/16" rear wheel cylinders, and suit HD, HR (passenger, rear), 6-cyl. LC, LJ (rear) with front discs.
1130SA shoes will be rocking-horse-poo rare, 2-1/4" wide with extended webbing for 9/16" rear wheel cylinders, and suit HD and HR commercials (rear) with front discs.

Postscript: Dr Terry commented on the scarcity of E1130 shoes earlier.
My HD X2 had 2-1/4" rear brakes. The rear shoes had had inserts welded in where the wheel cylinder pushrods would have been. I had no handbrake cable problems, although the first thing I do to any Holden with duo-servo rear brakes is to cut about ten coils off the handbrake cable springs. I find that the spring binds and prevents the handbrake applying fully.

Rob

[Errol62]

Gregory's is a last resort. Didn't think that sounded right.

An imperial (excludes US) inch is 25.40000000000000000000000"
......exactly. Personally I prefer mm these days.

Your information will be very useful to others thanks Rob. It is confusing. I'm sure my EH rear axle has skinnier shoes and drums than the one in playing with now. Will measure.

FB ute driver, EK van project

[Errol62]

Nope, they are same, 44.5mm. Drums are same worth but different offset. There must be a difference in the backing plate and or axle flange offset.

FB ute driver, EK van project