55 replies to this topic

[yel327]

Most likely.

[rexy]

Studs are cheap. Buy them before you get the discs drilled so they drill the correct size. Might as well go 1/2 inch as you are starting from scratch. Or find someone who can supply and fit. ABS used to do this sort of stuff years ago but I haven’t used them for anything for ages.

[Statler]

IF HQ calipers are so good , why were they changed for A9X ? 

 

I've been using A9X- ish ( HZ 4wd ) spec & i can't fault it. My pedal feel is better than Hoppers . 

 

Bonus is that it didn't need to be engineered . 

[yel327]

Mainly because HQ calipers were no longer made, they’d just use the latest thing off Holden/Statesman. I agree HZ/WB style are better than the older ones but for a street car the rotor diameter will be most of the gain.
My guess is you’d get far better pedal feel with multi-piston calipers if you upgraded to a VT master or similar rather than sticking with the old 1” bore style.

[76lxhatch]

The alloy calipers are lighter (and potentially dissipate heat better), and the later slide design is less prone to seizing up. There's probably a cost saving in there somewhere too. But the rigidity of the earlier calipers is better and unless they corrode they last longer, it doesn't matter so much when new or if you know you have good ones but when they're 35-40+ years old there's been a lot of stress through them and I've seen some that flex way too much.

 

The pedal feel with 1" master and AUII calipers is a little poor and a factory HQ-WB setup would definitely feel better. My master cylinder is the old 1" style but modified and stainless sleeved with a stepped bore so it takes a 1 1/8" piston for the front circuit, made a big improvement in pedal feel.