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Harv,

How did it go with the engineering ??

Greg

Passed with the engineer, all except the brake test and noise measurement (didn't have the dBa meter with him). He took it for a good squirt around Greystanes, and reckons the pedal will be borderline for being too heavy (despite the booster, vac pump and resevoir ). He wanted the car delivered to his property out at Bringelly to do the brake test over a couple of days.

The brake assessment process is more than a little interesting:
https://www.rms.nsw.gov.au/documents/ro ... manual.pdf

Because I replaced the entire braking system, I suspect I meet Modification Criteria 16 (Replacing the entire braking system with a combination of components either from a production vehicle or an after-market brake component manufacturer) on page 6. As the vehicle is manufactured prior to the introduction of ADR 31 on 1 January 1977, this become 16A. The table on page 13 then shows that for 16A, I have to undertake all the tests:

• Reservoir volume

• Mounting structure

• Park Brake

• Partial Failure front rear

• Booster failure

• Proportion valve failure

• ABS Failure (OK by me... I have no ABS)

• Spike stops

• Wheel lock

• Type-0 Engine disconnected

• Type-I Heating procedure

• Type-I Hot performance

• Type-I Recovery procedure

• Type-I Recovery performance

I dropped it off to him a week ago, hopefully pick it up this weekend.

Cheers,
Harv

Some good news.

Thanks for the link. I'll have to read that when I have a spare couple of days.

Sent from my SM-A705YN using Tapatalk

It's a NSW specific document... hopefully the crow-eater version is less demanding.

Cheers,
Harv

It’ll be worth it to get that larrikin auto on the road mate.


FB ute fixer upper, EK van on rotisserie

Harv,

A little curious but are you using disc brakes on the rear of your car ?

I am using drums so can cheat a little with slave cylinder sizes to up the braking capacity.

It's all a balancing act really, hopefully he'll give you good news.

Regards Greg

EK283 wrote: Wed Nov 27, 2019 8:43 am Harv,

A little curious but are you using disc brakes on the rear of your car ?

I am using drums so can cheat a little with slave cylinder sizes to up the braking capacity.

It's all a balancing act really, hopefully he'll give you good news.

Regards Greg

The vehicle was originally manufactured with a semi-huck hydraulic drum brakes front and rear, operated from a single non-boosted circuit. The vehicle front brakes were replaced with late model (VN-VP) ventilated brakes with single piston finned caliper, hydraulic actuation. The brakes have been mounted to the HR Holden front end by adaptor kit as supplied by the Castlemaine Rod Shop, inclusive of stub axles milled to suit the Commodore wheel bearing tolerances (part numbers SA11 and DB010). The rear brakes are VP Commodore disk brakes mounted to the VP Commodore limited slip differential as per original VP Commodore equipment. Both front and rear calipers have been coated in VHT red paint, good for at least an additional 10kW . A PBR VH151 vacuum brake booster has been fitted (sourced from a Holden TC-TE Gemini) together with a dual circuit master cylinder sourced from a &*#@ Falcon XB (PBR part number P6258a). The master cylinder pushrod has been extended by Hopper Stoppers to provide appropriate booster pre-load. The VH151 vacuum brake booster volume (1.4L) has been supplemented by a Protek VT1 vacuum tank (3.1L). The engine’s low vacuum (13”Hg at idle) has been managed by use of an Aeroflow AF49-150 electric twin piston vacuum pump, which draws from the vacuum tank (no connection between engine manifold pressure and brake system). The vacuum pump is controlled by a Hobbs switch. New brake lines have been run, splitting the brake circuit front/rear. The brake circuit differential pressure warning switch (integral to the P6258a master cylinder) has been retained, with a brake fail warning LED fitted to the "idiot light" instrument binnacle. The handbrake cable retains EK Holden front cable and clevis with a VP Commodore rear cable, joined by steel flatbar. Gusseted brackets are used to provide both cable support and standoff from the driveshaft/exhaust at full suspension travel. Brake balance is achieved through the use of a Bauer adjustable proportioning valve, mounted on the drivers side chassis rail.

Cheers,
Harv

Bugger. Looks like I've failed the Partial Failure brake test for the rear brakes. The test checks that if I blow out a front brake hose that the master cylinder is still able to drive the rear brakes hard enough to stop the car. It's done at 80km/h, and needs the car to decellerate at 2.55 m/s2. (9.2km/h per second). It is done by cracking open the bleed screw on the front brakes to simulate the hose failure.

With the front brakes disabled (i.e. bleed screw cracked open), my rear brakes are applying only slightly (not enough to even lock the rear tyres on grass). The brake pedal is not on the floor when the system is bottoming out, and the engineer has suggested it might be:

• The master cylinder does not push enough fluid to suit the rear callipers, or
• There is air in the rear brake circuit that needs bleeding out, or
• The brake pedal mechanism is bottoming out prevent full use of the master cylinder & booster travel, or
• The brake booster does not have enough travel to fully apply the master cylinder to its full range of travel, or
• The push rod between the booster and master cylinder is not long enough to apply the full travel of the master cylinder.

The engineer will have a fiddle today, but short of a miracle I'll pick the car up next time I'm home and have a rethink. Will give Burt Bros a call and get their opinion on the fix.

Patience, grasshopper.

Cheers,
Harv

Harv,

What about your brake balance adjuster ??

I use one on another car and until I cooked the front brakes I always thought it was working well. I should have realised that it wasn't working with the lack of rear shoe ware.

I would try bleeding first, then removing the balance adjuster. If that fails then some calculation on the master cylinder volume to the calliper ratio.

Good luck I will be watching with interest as my brakes are similar, HQ callipers with 10 inch fraud drums the only difference.

Greg

Harv,

You wrote,

• The master cylinder does not push enough fluid to suit the rear callipers

Nope. Won't be that. A caliper takes less fluid to apply than a wheel cylinder.

• There is air in the rear brake circuit that needs bleeding out

Uh-uh. I believe you are able to bleed brakes.

• The brake pedal mechanism is bottoming out prevent full use of the master cylinder & booster travel, or
• The brake booster does not have enough travel to fully apply the master cylinder to its full range of travel, or
• The push rod between the booster and master cylinder is not long enough to apply the full travel of the master cylinder.

Probably one of these three.

Troubleshooting: Are you using the original pedal box? If so, remove the brake pedal stop rubber and lengthen the booster pushrod to compensate. You'll gain some travel.

Rob

Geez Harv as far as I am aware we have to have a brake test but no where near the extent that you are having to go through at the moment and I hope our authority hasn't got a hold of those bloody rules it could make a whole lot of things even more difficult.
I look forward to hearing how you go with this and what the fix ultimately is.
I still have to prove my brakes under power and may need to use some of this fault finding.
Sounds like Rob has some good ideas.

Neil

Thanks gents.

I know that the pushrod between the master and the booster is the correct length. It had to be lengthened a poofteenth (by Hoppers Stoppers) to make sure that the preload on the master was correct. Hoppers know their brakes, so I'm confident that they have the right pushrod. Sadly, Hoppers is interstate so hard to get them to resolve my current issue.

Spoke to Burt Bros this morning. Their feel is that it is likely the adjustable proportioning valve, and that it should not be needed on a disc/disc car at all. It is possible that the engineer assumed the rears locked first during the first inspection test-drive. They suggest I remove the valve, and see how it goes. Need to run this past the engineer. Failing that, I need to take Rob's steer:

• The brake pedal mechanism is bottoming out prevent full use of the master cylinder & booster travel, or
• The brake booster does not have enough travel to fully apply the master cylinder to its full range of travel.

(i.e. play with stop and pedal/booster pushrod).

Cheers,
Harv

Hope it ends up being one of the easier options Harv.

Keep us posted Harv please.
Neil

My guess would be the proportional valve aswel