Thread: Brake Upgrade!

Did this conversion on my IIA shorty many years ago - very good conversion.

Hello again from Brisbane.

On the topic of changing over long to short wheel base model drums, you will occasionally get threads/posts criticising the single slave cylinder set up for its weakness in holding vehicles in a reversing direction - especially for triallers and people launching boats.

One suggestion I have come across several times is to also fit the 6/8 cylinder brakes on the rear axles backwards to give maximum braking in reverse.

I have no plans to try it on my own truck, but just note it for interest.

Cheers,

Originally Posted by JDNSW

Late Series 3 all models 109 went to 3" brakes. This is a good upgrade for a swb, but you will need to use the lwb master cylinder.

John

John,
does the LWB master cylinder move a greater volume to cope with the extra wheel cylinders on the front?


Cheers, Mick

Originally Posted by JDNSW

you will need to use the lwb master cylinder.

John

Hello again.

Presumably you will have to also decide between single or dual circuits when selecting a master cylinder - the later models had dual circuits and a failure warning light on the guage panel.

Single circuit is OK for most applications and makes for the easiest conversion.

Cheers,

The single cylinder dual piston brakes are referred to as single leading shoe and provide equal braking in forward as reverse direction. The two cylinder systems are twin leading shoe and are normally provided on the front wheels. This is because the front wheels provide most of the breaking force when travelling in the forward direction due to weight transfer from the rear to front wheels.

I would not advise to use a twin leading shoe in the reversed direction on the rear wheels as you need most breaking force in the forward direction due to the greater speed from that achieved in reverse. You need the contribution of that one leading shoe from the rear wheels when trying to pull up from high speeds achieved in the forward direction achieved from having multiple forward gears.

I did set up a mini with twin leading shoes on the front and also used a vacuum booster which was only connected to the front wheels to prevent rear wheel lock up when hard breaking from a high speed.

I never had to contend with holding a boat on a steep ramp though.

Originally Posted by mick88

John,
does the LWB master cylinder move a greater volume to cope with the extra wheel cylinders on the front?


Cheers, Mick

Yes.

John

Hello again.

Rather than start a new thread this one seemed appropriate.

A maintenance question.

My own 88" had most of the SWB to LWB drum conversion completed by the PO but not the master cylinder and vacuum booster. The brakes didn't work when it arrived and I haven't got it back on the road.

I bought a new master cylinder and booster and a second hand pedal tower off a wreck which is stripped down and painted. The pin and bushes for the pedal are OK so I will retain them.

What is the best lubricant for the pin and bushes? Or it reassembled dry?

Cheers,