VL Turbo brake booster.

[MikeM]

Can anyone confirm that a VL booster/master has a 1" bore and is comparable to a VN V8 type booster? I have hoppers VT disks in front and a VL turbo booster has come up and I am being assured that this is the same as the VN V8.

All help is appreciated.

[FATBOY]

if your running the vt discs and calipers you will need the 1 1/4 inch master cylinder from the vt . just been down that road for the brakes on my fe. you will also need adaptors or use the castelmaine rod shop dropped spindles as they come with the bolt holes for the late model calipers

cheers fatboy

[mcl1959]

OK Mike, here is the brake story.
VL Turbo has a 1 inch master cylinder and will be fine on your car.  VT step bore master cylinder has 1 1/4 inch primary bore which takes up the free play in the brake system and then reverts to 1 inch bore for the actual brake work - this is where the term "fast fill" comes from.  What this means is that you get about a quarter of an inch less pedal free play when you first push the brake pedal using a VT master cylinder but the actual braking performance is the same as any other 1 inch master.
The reason VT does this is because of the warping disc issue on VT and later Commodores, the calipers have a feature called "self retraction" built in which means that the caliper pistons pull back from the rotor more than normal to stop them rubbing on the rotors which therefore helps to eliminate rotor warping.
Now to the Hoppers Stoppers kit that you have - is it an old one, more than 2 years old?   If it is then it does in fact use VT rotors and calipers, but if it is less than 2 years old then it uses AU rotors and calipers which are completely different and dont have self retraction.
You also do not need CRS stub axles as the kit has adaptor plates to mount the calipers to the existing disc brake stub axles. (the VT caliper kit uses drum brake stub axles)
Things CRS dont tell you about their stub axles:
They are 3 inch drop on a HR front end - not 2 inch
They push the wheels out 3/4 inch from stock position
When you use them with Torana brakes and 13 inch wheels the wishbone is below the rim and lower than the 100 mm minimum  - this is illegal !
If you use them on a HR front end with HQ pattern wheels on an early Holden (eg FE or FC) the wheels will hit the mudguards when you hit a bump going round a corner.
Now if you have VT rotors and are building a car from scratch then the best thing to do would be to use a VT booster and master cylinder, but if you are just adding a master to an existing car then the VL master will be fine however all pipe fittings will have to be changed to metric to suit the VL master.  If you are running a manual box you will have to move the clutch master cylinder over to the left a little bit for clearance around the booster as well. This will involve moving the clutch pedal a corresponding amount to the left as well.
If you need more info contact me as I have done this conversion on over a dozen cars and believe me the brakes work VERY WELL !
Ken

[MikeM]

Thanx Ken,

this is great info and I understand that I need to run new brake lines (for licencing I have to get an engineers report and the engineer wants the brake folks to write him a letter, so I am going to get them to run the lines and get that assurance.  The whole conversion started with getting better brakes, so I need to get that right .  I run a shortened VS diff in the back, so I dont expect it should be too hard.  

I have taken the VS booster and removed the part that keeps attaches to the firewall, this I have cut the existing bolts off, fitted new ones that I use to fit-up to the old master mounts.  This I have fitted up with some brackets onto the VL booster.  After fitting this leaves the brake pedal about 1" short of the pedal (when fully extended), so I am welding a bracket to the pedal, so I can keep the existing brake switch and bump stop as well as give me that play that is needed to soak up that 1/4" of free play.

Sound reasonable?