Just got my hydo handbrake working in the coupe, Fairly straight forward apart from, having some trouble with the double flaring tool. Hopefully will get to test it out with some drifting and motorkhana soon. One tip for guys with r31 diffs, you cant use hydro with r31 calipers as they seize up. But commodore ones are a direct replacement. Found this out the hard way so will have to head up to u-pull-it tomorrow and get some calipers.

Why have the calipers seized? If it is just plumbed into the rear line I would expect there is an issue elsewhere, probably the h/brake master cyl not releasing pressure?
The calipers are at the end of the line to speak and the only way they can seize is if the fluid pressure isn't being released. What has changed - only the addition of the h/brakem/cyl..

Yer its got me a bit stuffed, but i have read r31 forums and thats what everyone saying. Doesn't make sense to me

Thats weird...

The m/cyl doesn't have a drum brake style residual pressure valve in it still does it?

From memory the were something like a Hillman Imp m/cyl and they may have had drums all round??

Try using it and getting the calipers to seize, then crack the lines going into the calipers (be careful as there could be quite a bit of pressure in there!), if there is pressure the I reckon your h/brake m/cyl is not releasing pressure comepletely.

Is the h/brake adjusted so there is freeplay at the m/cyl? If the m/cyl is not returning all the way back then you will hold pressure in the rear lines. I reckon the h/brake lever should have a spring return so it always returns comepletely. Is the carpet holding the h/brake lever on slightly?

may i know what seat is that from?? looks nice

Just swapped calipers over to vs commodore ones. The 31 ones where jammed on there tight but no pressure in lines. It my understanding r31 brakes adjust themselves and the hydro causes them to jam. Haven't tested yet but think it will be better.

The seats are after market Zenzo racing ones from motoquipe. pretty good as they are tight but still recliner.