Here's a cost-effective CAST Sigma strut (3 bolt pattern) brake upgrade.
As we know, these struts are a great bolt-on upgrade for GA-D Galants and LA-LC Lancers.
I've done two of these now so thought I would share the process - no responsibility taken obviously for other people's work/interpretations etc etc.....do so at your own risk.
We've seen upgrades for 'Green' struts, however there are a huge number of cast struts that have been either thrown away or left under benches because it was too hard to find a suitable bolt-on brake upgrade.
For anyone with just basic tools (ie: no machine shop equipment etc) this upgrade can easily be done in the average shed.
What you will need:
Rotors: Starion JA-B-D (DR400) $180 pair (Ebay)
Calipers: Ford Focus 2004 onwards $48 pair (Pick-a-Part) Be sure to keep the flex brake lines and the 15mm caliper mounting bolts when you remove them.
6 x 10mm longer than stock lower strut mount bolts.
Some 10mm flat steel plate (100mm x 200mm will be plenty)
Drillset (pedestal drill will help but not crucial)
6"grinder with grinding discs, cut-off and flapper wheels.
Rat tail file
Brake line (bundy tube) flaring tool - buy a basic one off Ebay or borrow one?
Optional (but recommended) - Starion, 15/16th (or larger 1") master cylinder. $129 US Ebay
You'll get a much better pedal by upgrading the master - particularly if you're adding rear discs at some point too.
Optional: braided flex lines - made to order at most reputable brake joints $45 each
This is a finished front set-up on my GTO rally car - has done one eventnumerous drives and works beautifully.
The Starion rotors bolt straight onto the Sigma hubs - no mods at all.
The caliper mounting holes on the strut are 89mm and the Focus calipers are 90mm so you will need to file 1/2mm from each hole for the caliper to fit nicely.
It will just bolt up without any filing but you should have ease-of-fitment...and 1/2mm will have no adverse effect on the mount's strength.
NOTE:: The Focus calipers need to swapped - Left caliper goes on the RIGHT strut, right caliper on the LEFT strut (so the bleed nipple remains at the top of the caliper)
These are the caliper bolts you saved - you will need to cut them down as pictured because the Sigma strut is thinner where the caliper mounts than the Focus one and the bolts will go through too far and hit the rotor. They need to finish flush with the inside of the caliper mount (you will see what I mean when you bolt it all together). When doing the final fitment, be sure to use thread locker just as they do when fitted on the Focus originally.
This is the main caliper bracket - I simply cleaned-up the castings for a neater fit with a flapper wheel. One of the set-ups I did sat perfectly centered and one sat slightly off-centre, hence the 'tidied-up' caliper. Use your own judgement when doing your own.
This is one perfectly centered.
And this is another one.....slightly off-centre. Still operates perfectly fine, just depends on how fussy you are. Obviously some discrepancies with caliper castings.
*For the pads to sit nicely on the rotor, a small concave needs to be ground on the underside or it will just foul the rotor 'hat'. I probably got a little excited - it really doesn't need much - pads are pretty cheap for Focus calipers anyway.
I use 'Red Stuff' competition pads which aren't cheap but work brilliantly for the rally car. Choose to suit your budget.
This only needs to be done on the outside pad - the inside pad is fine.
Next, you'll need to re-flare the solid line to suit the Focus caliper's flexi line.
I replaced the Focus ones with braided lines I had made up for $45e so didn't think to document it at the time. Re-flaring is pretty easy if you have (or can borrow) a flaring tool. Another option is to have a brake joint simply change the ends of the flex lines to suit the Mitsu hardline. Either way it's inexpensive.
Right, so that's the caliper and rotor sorted - this next pic shows the setup actually fitting inside a 13" mag wheel!! I won't guarantee it will fit under your 13' wheel as I tried 3 different types and it cleared 2 but just fouled on the 3rd. The calipers don't protrude past the face of the hub so you should be fine fitting a wide variety of wheels over this set-up.
It will safely fit under 14" wheels which is the smallest most use these days anyway.
Now onto the only 'fabricating' part of the job......with a brief explanation
My GTO is a replica of the Factory 'Works' Rally GTO which ran a 'Safari-Spec' spacer between the bottom of the strut and the control arm. Why? Not 100% sure but I do know it alters the roll-centre characteristics. As to any real-world effect, I can't feel any difference at all in how it drives when they're fitted...
Anyway, I made and fitted the spacers with the rebuilt struts and new brake set-up - all good...........then I discovered the only way to fit this brake conversion (on a Galant anyway) was to have these spacers fitted! The lower caliper slide pin fouls the tie-rod end nut if you don't use the spacer.....
So, get your 10mm steel plate and start cutting/drilling. It's a bit of a PIA to have to do it.....but it's just a bit of time and costs virtually nothing.
Remember to drill a hole for the locating dowel too so it locks the strut in nicely. (you can see the punch mark on the plate on the centre left side)
If your Gally is lowered substantially, this will actually help with the roll centre angles.....
THIS is what you should end up with....
Here's the spacer installed.
This is the pin now clearing the tie-rod nut......you may get yours to clear by trimming down the threaded section but not something I was comfortable doing...
So, that's about it, a pretty decent, vented brake upgrade including Master Cylinder for around $600.....or less if you sniff out some bargains......that's around half the price of some 'options' out there for Green struts and makes use of some old Sigma parts that many of us have discarded in the past.
Cheers.