heinzboehmer's 2002 Topaz 6MT Coupe

[heinzboehmer]

Got a good amount of work done over the last few days.

Started with the front brakes. Before:



After:



I did have to grind both front hubs down a little, but it was no big deal. 30 seconds with an angle grinder was all it took:



Here's why I'm planning for brake ducts v2:



That wavy cast part is the rotor hat that extends inboard and almost entirely blocks airflow to the rotor ring. I'll run these same brake ducts for my next track day (because I won't have time to get the next version done), but yeah these need updating.

Then I did the rears:



I thought these were much more annoying. There's less space everywhere and cutting the heat shield was a tedious job. But all in all also not a super difficult job.


While the car was up in the air, I also did a few other jobs I've been meaning to do for a while.

First, swapped out front control arms and engine mounts. For some unknown reason, I previously used uro control arms when I did my rod bearings. I've been wanting to swap them out for a long time, but had been lazy. Similar deal with engine mounts. Had vibratechnics in there and grew tired of the increased NVH pretty quickly.

Fortunately, only took me a couple hours to do both. Used an engine support bar to suspend the engine and then lowered the subframe a bit. Doing this made the job sooo much easier. Unfortunately no pics, but you can see one of the brand new control arms in some of the pics above. For the engine mounts, you'll have have to believe me. Very excited to have a smooth idle again.

I also added a second exhaust brace like Bry5on suggested:



Another NVH upgrade!

Anyway, only managed to do the hydraulic part for one of the calipers yesterday. Hopefully I can get the rest done today and then take the car out for a spin.

[heinzboehmer]

Air would have to get sucked out of the caliper with this setup

Looks like Range Rover does something similar for the SVR:





However, as far as I can tell, these ducts are designed to push air into the caliper instead of pulling air out.

I guess I could also swap rotors from side to side on my car and do the same. Don't love the idea because the rotors (and entire sprung assembly, really) are designed to pull air in through the center of the rotor and evacuate it along the circumference. Plus, active brake temp monitoring and cooling sounds like a much cooler project


Anyway, track wheels have arrived and I have a friend who just got a 3d scanner, so I think I need to finish up the brake swap and then get the car and wheels over to his place. With the area scanned, I can start doing some CAD work and decide whether this is even feasible under 17s.



Edit: No surprise, some racecars do this too. Pic of the 488 challenge front brake below. Looks like this one also pushes air into the rotor:



This is likely what my design would have to look like. Basically just follow the radius of the caliper so that there's no interference with the wheel. No hump over the caliper like the Mustang and Range Rover solutions. Would likely go for a fully enclosed design though, skipping that opening over the pin that this one has.

[heinzboehmer]

Interested in seeing how the fronts look. Should have them disassembled by tonight.

Alright finished disassembling. Fronts looked much better. Ended up counting a total of four ripped seals.




I also bought some Krytox 205 to use as assembly lube, on recommendation from some friends. Ran a quick experiment to test it out. Popped a piston out and then reinstalled with just brake fluid. Needed to use a good chunk of my body weight to get it in. Then cleaned up piston and bore and coated in Krytox. Was able to get the piston in by just pinching the caliper with my thumb and index. Crazy how much of a difference it made.

Good to know that this was installer error and not an issue with the seals. And as I said before, good lesson to learn.

[heinzboehmer]

Also, I was at laguna seca for car week stuff this past weekend and Ford had a display with parts from that new homologated GT3 mustang thing. This is what the rear brakes looked like:




Given the design of the front CSL rotors, my current brake ducts will be way less effective and this design looks super appealing. I don't know if I'll have enough clearance under 17s to do something similar, but it would be super cool to build something like this. Air would have to get sucked out of the caliper with this setup and I can think of two ways to do this:

1. Build an active system that pulls air out with a fan at the end of the brake duct hose. This is appealing because it can get combined with a temp sensor to make sure that the pads are always in their optimal operating temp range. Can also log individual caliper temps.
2. Build a passive system with a venturi tube or similar that creates a vacuum in the brake duct hose so that air gets pulled out at speed. Simpler than the active system, but no control over caliper temp, some added drag and potential for overheating on lower speed tracks.

Just brainstorming right now, but thought the design was cool and would make for a fun project.

[heinzboehmer]

I thought the seals felt too tight when installing the pistons...

This is the only seal that was obviously bad when pressure tested, but now I don't trust any of the others. I really don't want to find out that another seal is ripped while on track, so I've decided to rebuild all of the calipers again. New seals are on their way.

Fully disassembled the rears. 3 out of 8 seals were ripped, yikes. The other two I found weren't ripped as bad as the one that inflated the dust boot, but still. I'm glad that one failed catastrophically, otherwise I wouldn't have taken these apart.

Interested in seeing how the fronts look. Should have them disassembled by tonight.

Also, found a good way to pop the pistons out:

1. Leave the caliper fully assembled and stuff some wood/cardboard in such that the outboard pistons can't move much and the inboard pistons contact the wood/cardboard right before popping out.
2. Pull inboard pistons out with fingers. Should be easy to do if step 1 was done correctly.
3. Remove crossover pipe and replace with a bleeder in the outboard port.
4. Stuff some more wood/cardboard in such that the outboard pistons contact the wood/cardboard right before popping out.
5. Pull outboard pistons out with fingers. Should be easy to do if step 4 was done correctly.

The above approach was much faster than what I did the first time around and there's no risk of damage to the pistons when prying.

[Sharocks]

What do you think of a version of that bulkhead panel with a ski-pass through? Would the rigidity be compromised?

Absolutely would be compromised, but for a street car this is way overkill lol

[heinzboehmer]

Yeah I'll definitely report back with how the seals hold up. Have a long track day on Sep 18 (7, 30 min sessions), so will update with how they did.

[Obioban]

I meant titanium heat shields between pad and caliper.

If you run black seals and titanium shields, and my friend runs blue silicon seals, and no shields, we'll really have some good info on what's needed!

[heinzboehmer]

Are you planning to run heat shields?

You're talking about heat shields between pad and caliper or between rotor and chassis?

Either way, I'll be running both. Still need to run the experiment to decide between titanium shims or stock porsche noise isolators.

[Obioban]

Are you planning to run heat shields?

[heinzboehmer]

Started on the brake work.

Quick pic of everything before starting:



Rebuilding the calipers. Decided to use girodisc seals and brembo dust boots after hearing of a friend's experiences on track with the girodisc boots:



And fully dressed:



Unfortunately this is where I realized something went very wrong during the rebuild. Pressure tested the calipers with air and found this:




I thought the seals felt too tight when installing the pistons...

This is the only seal that was obviously bad when pressure tested, but now I don't trust any of the others. I really don't want to find out that another seal is ripped while on track, so I've decided to rebuild all of the calipers again. New seals are on their way.

The more I think about this, the more I lean towards this being an installation issue. I decided to lubricate everything during the install with just brake fluid, but I really should have used assembly fluid. Oh well, at least it was a good learning experience.

Have ordered some assembly fluid for next round. Hopefully that solves all my issues.

[heinzboehmer]

What do you think of a version of that bulkhead panel with a ski-pass through? Would the rigidity be compromised?

It likely would.

[nyc951]

This is when I have to ask, is this actually worth it lol

I like having a pass through, makes the car useable since the backseats at least for me are useless now because of my Recaros.

What do you think of a version of that bulkhead panel with a ski-pass through? Would the rigidity be compromised?

[heinzboehmer]

I like the look - all business.

Thanks! That was the intention

Brake dust colored too, so I don't have to worry about keeping them super clean

[D-O]

I like the look - all business.