2 pot rear calliper install (now with Brembo's)

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2 pot rear calliper install (now with Brembo's)

Postby tu » Sun Dec 30, 2007 2:16 pm

Anyone familiar with the early model rexes will know what a shabbily braked package they are straight out of the box. The four pot brake calliper upgrade for the fronts is a relatively straightforward bolt-on and makes a big improvement - and also makes it super easy to change brake pads.

Upgrading to the rear two-pot callipers as found on the later model rexes, and the GC STi-RA's and 22B was a much bigger proposition... requiring removing everything back to the backing plates and changing these over. It felt like a headache job so I never really pursued it too much - even if a matching set of 2-pots sounded like a tempting idea.

But in my travels I came across a set of sexy brake calliper adaptors which I thought I'd give a try....

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So, armed with my new brackets, a set of brake calipers, a set of discs, some brake fluid and a couple of cans of brake clean I got stuck into fitting things up.

First things first - as I was going to be working without a rear handbrake for a fair bit of the install, and also bleeding brakes - I jacked the car up sat it on four jack stands with all wheel off the ground.

So - first wheel off this is what I had -

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Note sliding one pot rear calliper & the solid rear disc - really just one step above drum brakes. A decent spray of brake clean will make things a bit nicer to work on at this stage.

Two 14mm bolts hold the calliper to the backing plate - remove these and move the calliper out the way (I have it sitting on the swaybar in this pic - be careful not to damage your brake lines or just leave it hanging)

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The disc should slide straight off but this side was a little sticky - a pair of M8 bolts in the disc holes will pop it loose. Also - remember not to leave the handbrake on....

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This shows the difference between the factory disc and the later model disc (in this case a DBA4653)

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Just test fitting to see how it sits.... ba bow - the new disc fouls the stone guard

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The stone guard is spot welded to the backing plate - time to say goodbye..... With a 8-10mm drill bit the spot welds needed to be drilled out. I covered the handbrake mechanism first to limit the amount of shrapnel getting in there whilst I drilled.

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And minus stone guard...

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And the offending stone guard. The spot welds needed a little help from a cold chisel as well (Note safety boots in this pic)

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New disc fits perfectly now :) Give the disc a good dose of brake clean to get the machine oil off.

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Test fitting everything. The calliper brackets use an 8mm allen head bolt to mount to the backing plate and calliper.

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Wearing some rubber gloves and holding a glass jar underneath to catch any fluid I swapped the brake line over to the new calliper. A bit of brake clean will get rid of any spills. I used a set of new copper washers on the banjo bolt as well. Clean up spills quickly as brake fluid does nothing good for painted parts.

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And then after bolting the calliper into place and installing pads this is what I had

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And the other side (note - don't spill jar of brake fluid)

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After the callipers are all in place give then a good clean up with some brake clean - you will have dropped a bit of brake fluid around the place so best to get it all cleaned up quickly. It will also make it a lot easier to find any leaks. The final stage is to bleed the brakes - give them a good bleed and don't be stingy on the fluid. It'll take a few goes to get the pedal nice and solid again. Expect to use at least 1 bottle of brake fluid.

And the finished job looks like -

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Last edited by tu on Mon Apr 19, 2010 1:38 pm, edited 1 time in total.
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Postby Random Dude » Sun Dec 30, 2007 4:04 pm

Very nice Adam :)

Thanks for taking the time to do the DIY.

Something to ponder over! Has the braking balance felt any different?
Brenton

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Postby bumblebee » Sun Dec 30, 2007 5:51 pm

OMG Adam. :shock:
:pizza: Awesome. Well done.
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Postby tu » Sun Dec 30, 2007 6:09 pm

I haven't had a really good chance to test them out with any degree of seriousness but after bedding in the pads a bit I reckon they really do even things up quite a bit. I don't know how much by but the butt gauge says this is a winner. The pad combo I am using is Mintex Xtreme on the fronts and Endless CC-A's on the rear.

The discs on the 99-00 models aren't any larger in diameter although the pads are marginally and the discs are vented - backing plates are identical though so this applies to those models as well.

Even better thing is it makes the pads super easy to change, and saves me having to paint the rear calipers to match the fronts :D

I thought you'd like this Bumblebee :)
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Postby Age » Sun Dec 30, 2007 7:14 pm

Very nicely done there Adam!! :cheer: :cheer:
Chalk up another successful mod done at the vast Tuspeed workshop! :thumbs:

Now for the question i'm sure you'll get asked.... how much?? :giggle:
Maybe Tuspeed could put together the "GC8 2 pot rear brake kit". (of course maybe with Rampant's help with the calipers :wink: )

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Postby FLYREX » Sun Dec 30, 2007 8:38 pm

Great DYI Adam :D

I liked the handy tips too......




















(such as "don't spill the jar of brake fluid")
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Postby Mr Corduroy » Sun Dec 30, 2007 10:05 pm

Nice job.

And those adapters are one sexy bit of gear.

I read on Campbell's DIY about ugrading the RX brakes that holding the brake pedal to the floor will stop the brake fluid draining out while changing over calipers. I tried it whem swapping to front 4 pots on my MY98 and it worked a treat.
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Postby PAT555 » Tue Jan 15, 2008 9:05 pm

Adam in a couple of those pics the adapter looks very close to the disc.
Is that just because the disc was not seated securely?

If the clearance is only a couple of millimeters it may not be enough as when the discs get hot they will expand and rub.
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Postby tu » Tue Jan 15, 2008 9:46 pm

I know what you mean there re the space between the disc and the bracket but it's actually just the photo itself - I actually noticed that when I was going through the pics and I went and had another look at them for my own piece of mind. The caliper is held in the same position as the factory bracket - there's a pretty decent gap in there so hopefully should be right.

Also re the braking performance difference I've really noticed some decent change in how the car sits during braking - it sits much flatter. I think I need to do some testing and quantify the difference on the G sensor on the RSM-GP. And then it's time to upgrade the fronts again :wink:
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Postby Mr Corduroy » Tue Jan 15, 2008 10:15 pm

tu wrote: . . .Also re the braking performance difference I've really noticed some decent change in how the car sits during braking - it sits much flatter. . .


A bit more rear bias will do that. I once massively upgraded the front brakes of a car without installing the matching proportioning valve for the rears. The car was always very 'stable' under braking. Unfortunately it also suffered premature rear wheel lock up, so I fitted the proportioning valve in the end. Obviously this was before ABS!
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Re: Rear brake envy - 2 pot rear calliper install on a GC MY98

Postby tu » Mon Apr 19, 2010 1:12 pm

Just as a bit of an addendum to this install - I get asked a lot if the Kartboy brackets fit with the STi Brembos and thought I would document it to show what needs to happen. They do - but the bolts have a different thread so you need to reuse the STi bolts, and because of the shape of the back of the Brembos you need to remove a bit of material off the bracket to get them to sit right. It's a quick and straightforward job - and the following should give an idea of what's involved.

Here is the bracket in position on the back of the Brembo calliper - you can see it fouls around the bosses on the back of the calliper.
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Shot of the back of the Brembo rear calliper - the two pot Subaru callipers are a lot flatter on the back.
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Enough material removed for the bracket to fit up. Note after this pic I rounded out the notches to remove any stress points
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The completed job
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Re: 2 pot rear calliper install (now with Brembo's)

Postby deuce » Sat May 22, 2010 6:13 pm

How much are there brackets and are they available?, have a 94 model and looking to do a brake upgrade soon.

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Re: 2 pot rear calliper install (now with Brembo's)

Postby Sime » Thu Jun 10, 2010 9:51 am

Excellent write-up Adam! I am fitting these up to a customer's STi atm.

Just as an addendum to those considering the mod, you can buy an 8mm spot weld remover drill bit. They're typically $15-20 and most automotive paint supply places have them. They make short work of the spot welds and in addition to leaving a nice clean surface after removal of the backing plate, you don't need to worry about using the cold chisel.

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Re: 2 pot rear calliper install (now with Brembo's)

Postby Mr Corduroy » Wed May 15, 2013 8:43 pm

Thanks Adam. Fitted my rear brembos with your Kartboy dogbones and rear disks (plus these instructions) last weekend no probs.

A couple of observations:
    Those Kartboy dogbones are made of something very hard! It took the old bench grinder a little while to grind notches to accomodate the Brembos.
    The bolt spacing on the car's backing plates wasn't a perfect fit with the Kartboy dogbones, and I had to slot one hole slightly.
    As you can see from your pic, re-using the brembo caliper mounting bolts means the heads are recessed within the Kartboy dogbones, leaving very little head left to get a spanner to. I'm sure this will end in rounded bolt heads and tears in the future when it comes time to undo the bolts. It would be good to replace them with socket head bolts.

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