15 replies to this topic

[Toranamat69]

I have got my hands on a spare UC Torana double diaphragm booster (same as the one on my car... can't remember the PBR number at the moment) and I want to modify it to take the diagonal mount A9X type master cylinder.

I have the case popped in half and the unit all disassembled but the studs for the brake master cylinder look to be welded in

My Questions are

1. How do you remove these existing studs without damaging the housing?

2. Where do I get replacement studs as it looks like the existing ones will need to be destroyed to get them out.

3. How much does the length of master cylinder pushrod have to change to suit the A9X master cylinder?

Thanks

M@

[dattoman]

The easy way is to get yourself a double diaph unit off a VB-VR commdoore
Swap the front shell and pushrod together
This way you'll have the rod length right and the studs in the right spot

Alternatively cut the studs off with a hacksaw. Braze some bolts into the front cannister from inside...... all the way round so it doesn't leak.
Modifying the pushrod is a pain

For my car I have the same booster as you and a commy one and I'll be doing it the easy way.

[Toranamat69]

Thanks guys.

Datto, you told me that ^^^ a while ago but someone else told me if you try to put the UC torana and the commodore halves together - you end up with the front half of the booster clocked around at an angle and it is impossible to line it up.

Have you actually tried the 2 together to confirm they line up?

[dattoman]

Yup
They do line up
At least they do on mine
We checked it just last week but haven't actually made mine yet.

[Toranamat69]

Excellent, I like making my life easier, I'll go and get a commodore one too.

Can you achieve a similar thing with a torana single diaphragm booster and get the diagonal mounting from front half of a single diaphragm commodore booster too?

[dattoman]

In therory yes
If you get the right single diaph commy one.... VB-VH
I've never looked at this before so unsure if the rod length is spot on but it might just be
But then you'd have essentially a VH404 off a 8/79 on UC

[dattoman]

All Toranas LH-LX and most UC on ran a 1" master cylinder regarless of the amount of cylinders under the hood.
Late UC with plastic bottles on their masters ran the Commodore 15/16" one

LC and LJ 6's ran a 1" too
4's ran a different one but no-one wants to talk about those anyway

[dattoman]

Because UC's and Commodores suck ?

[Dr Terry]

Hi Guys.

Nics to see the forum up & going again.

On the subject of 1" vs 15/16" diam. master cylinders, smaller or bigger isn't the issue. Smaller is not bad, depending on what result you want.

It's to do with the master vs wheel cylinder size ratio. With all things being equal a smaller master cylinder will stop the same with less pedal effort, but slightly more travel. The larger master cyl will stop the car the same, but with MORE pedal effort required & less travel (or a firmer feel) some poeople prefer this. Some drivers like a softer pedal with less effort required, but 1 is not better or worse than the other for everybody.

Dr Terry

[Toranamat69]

Well said Dr Terry.

There is quite a few different combo's of pedal feel you can get on the LH/X/UC's too with all the combo's of vacuum booster, master cylinders and pedal types.

M@