I found an IROC with a disc brake rear axle. I have a drum brake brake setup, and will be putting the IROC axle in. Do the disc brake systems have different brake lines or master cylinders than the drum brake setup? What else is different (besides the obvious rotors, calipers, etc). Thanks.

 

You need to replace the proportioning valve also. The Iroc one has both brake lines coming from the bottom. I am told the older drum proportioning valves have one line coming from the front of the pv. My swap was into a 90 RS. I found the parking brake lever was a different design than the 88 Iroc I was swapping from. The Iroc has a adjustable rod on the equalizer where the 2 cables going to the rear discs connect. My 90 had no adjustment. I will have to swap in the parking brake mechanism also, but am waiting until I do my T5 swap. Be sure to use the pb cables for the disc rear as they are different than the drum ones in length. If you order new disc pb cables as I did you may find it has a tightly coiled spring at the end. I had to cut this off carefully using a dremel and a cutoff abrasive disc, PITA. If you do, be careful not to overheat the cable and damage the plastic protective sleeve. Good luck, Lon.

 

Lonsal,

Your PV description is exactly what I have encountered. What have others done about the brake line difference?

 

I got the whole brake line from a donor car, was charged $5 for it. I sprayed brake cleaner thru it, blew it out with water-free/oil-free shop air, and hung it to dry for a day or so.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards

 

I got an adj prop valve from GM. Get one from summit racing, they are cheaper.

I found a fitting to split the front line from the master cylinder into the 2 brake lines. I had to put non-metric ends on and reflare the lines to do that.

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Michael Graeber

My Garage

1)83 Z-28 T-Top: Full cage, 9" w/ lad.bars, Midwest Engine Tech 406sbc,Strip Dominator, Demon Carb, Phase VI Chevy Bowtie heads, .630" Crower roller set-up, 1 3/4 coated Hookers 3" true dual exhaust th400, fuel cell & still not running

2)89 Formula WS-6 305 TPI Auto For the road: minor motor, more suspension stuff. MODS