Brake booster delete - mounting plate

madjak · Postby **madjak** » Sat Oct 31, 2015 11:08 am

I've tried running my car with no vacuum line hooked up to the brake booster and I much prefer the feel. You have to apply lots more force however the response feels more linear. It would probably be better with some additional leverage so as part of the booster delete I'll be making an offset billet plate to mount and lift the master cylinder 10mm. This will allow for some addition adjustment to the brake leverage if required. Stock pedal ratio is 4:1 but this could be increased to 5:1 or even 6:1.

If anyone else is keen to try it, I can make up some additional plates as part of the process. It's basically a thick alloy packer that bolts to the firewall that has two studs to mount the master cylinder. The pedal will need to be drilled to mount the clevis with a custom pushrod.

3gress · Postby **3gress** » Sat Oct 31, 2015 11:26 pm

Something like this? With a custom length rod and the master raised up just a touch to change the leverage point on the (redrilled) pedal arm?
Yes, i'd be certainly interested. Can you contact me if you go ahead with the project? Thanks mate.

madjak · Postby **madjak** » Sun Nov 01, 2015 1:09 am

Yes exactly like that but with the center hole and mount studs 10mm higher. I'll also make it with vertical mount holes for the willwood masters do you can run 1" or 15/16" dual masters.

plohl · Postby **plohl** » Sun Nov 01, 2015 7:05 am

I too could be interested....

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gslender · Postby **gslender** » Sun Nov 01, 2015 7:46 am

Yep, interested.

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madjak · Postby **madjak** » Sun Nov 01, 2015 11:08 am

Sounds like it's worth making a few. I'll draw up the plate and get them cut. The hardest part is getting to the bolts that hold the pedal box especially wuth a cage. Last time I got my 6 year old to get the ratchet onto them!

Are there any other tweaks anyone wants? Might try and make a brace for it at the same time... either to the suspension mount or a brace to the chassis.

Magpie · Postby **Magpie** » Sun Nov 01, 2015 6:06 pm

Count me in, just in case

madjak · Postby **madjak** » Mon Nov 02, 2015 2:21 pm

I'll get 6 plates cut up. I don't expect them to be very expensive, probably $30-50 each depending on how thick the ally has to be.

I have an event this weekend, but I'll pull out my booster after that, take measurements and get them cut later in the following few weeks. It will be nice to remove that rusty old booster and free up some space!

I really think anyone with a track car would much prefer having no booster. I've found the braking feel to be far improved, however I really have to adjust to pushing a lot harder to stop the car. Hopefully a higher ratio pedal will fix that downside a bit.

3gress · Postby **3gress** » Mon Nov 02, 2015 3:03 pm

Shoot me a pm when you want some cash and a postal address, thanks mate.

irwin83r · Postby **irwin83r** » Mon Nov 02, 2015 6:25 pm

hey how'd you go with this?
i was looking to fab something similar up over the next few weeks, but if you have ones done id gladly buy one.

cheers.

just read the rest of your posts.
no problems. like the others said let me know when you need details if there are any spares

Magpie · Postby **Magpie** » Mon Nov 02, 2015 6:42 pm

Happy with the price.

madjak · Postby **madjak** » Fri Nov 06, 2015 1:21 pm

ok new plan... I'm thinking I might install a balance bar directly to the back of the pedal via a bracket with adjustable holes, then mount two master cylinders on the firewall as planned. This would be a compact solution that would give the best outcome without going to a modified pedal box. It will require some additional holes in the firewall and a larger bracket but I think it will be worth it.

I'll probably use 2 x 76 series Tilton master cylinders so I can run brake pressure sensors on each (they have two ports) but other masters like wilwood could be used as they all have the same mount points.

Who is interested in this option of the stock dual master? I will probably make both brackets up anyway.

gslender · Postby **gslender** » Fri Nov 06, 2015 2:44 pm

madjak wrote:Who is interested in this option of the stock dual master? I will probably make both brackets up anyway.

Interested, but can you mock up a diagram or something to explain a wee bit better on what you're proposing - probably better to assume I'm not a brake component expert and not 100% sure what a balance bar is etc... yeah, I could google it, but then I'm assuming what you describe is what I think I found online posted by some other dude who might be as clueless as me etc...

madjak · Postby **madjak** » Fri Nov 06, 2015 4:26 pm

I went to the trouble of modeling it in 3D, only to do a google and basically find something the same... It's not an mx5 though but it's basically the same.

here is my 3D model mockup: (not to scale)

Basically I'll need to pull out the stock pedal box and see if the balance bar will fit in with minor mods. The masters are fairly straight forward to bolt up but will require some new holes in the firewall. The design I'll go for is an adjustable bracket that bolts to the brake pedal so that it can be incremented upwards or downwards to adjust pedal ratio. These brackets will be welded to the balance bar central spherical.

A dual master system is the best for a few reasons.
1. You can have different sized masters to suit the brake calipers you run
2. You can move the brake bias 50% either direction in a linear fashion, rather than just restricting the rear.
3. Two entirely separate fluid systems. If one fails, you can usually still get brakes on the other (subject to movement of the balance bar)
4. In cockpit adjustments
5. It's what proper race cars run!

A couple of negatives
1. more moving parts and more cost
2. can add some friction to the brake system so the joints need to be free moving

only one way to find out if it will work well and that is to build it