Brake booster delete - mounting plate

[Ice88]

G, could you enlighten me on what model that master cylinder is from?

Yep, it is a combo brake/clutch Master Cylinder Mazda 323 BJ 1.6L non-ABS 09/98-05/02

G

Same master on all BJs, part number:
BJ3D4340Z

[hks_kansei]

For reference as well the rebuild kit for these is the same as an NA master.

my GF rebuilt her NA6 master cyl a month or tow back and used the 323 kit (no MX5 kit listed in the catalogue for some reason)

Not 100% sure it was a BJ one, but that sounds about right (also right for the timefame)

[Magpie]

I had almost the same setup a G's with respect to the brake/clutch to make room for the ITB's, worked a treat with the Pipercross sausage airfilter.

Note the strut brace (tool rest, arm rest or cable tie thingy) has been removed as has the Pipercross...


DSCN1867 by Eipeip, on Flickr[/quote]

[3gress]

Thanks for the info fellas. My na6 master needs a rebuild and i was considering lopping off/welding the banjo port and using a tee fitting from the opposite front brake feed port for room. Still considering the booster delete or indeed complete re-engineering of brake system for itb space. The road car status has me pondering the legal/liable implications.

[hks_kansei]

For a road car, where you probably want vac assist still (I would anyway) has anybody thought of doing a remote brake booster setup?

you'd be able to buy yourself a lot of room, and stick the booster wherever you want (passenger side would probably be easiest)


All the room, and you can keep the vac assist.



Still not likely to be legal (depending on state) but another option.

[madjak]

Given my balance bar setup is basically the same master cylinder sizing as stock (ie same pedal effort), I think a simple booster delete with a 50% increase to the pedal ratio will be sufficient for road use. This is my guesstimate based on my brake setup though so might loose some effectiveness with smaller diameter brakes, but gain some with street pads that work when cold. I really think if I changed the pedal ratio on mine from 4:1 to 6:1, it would make for great brakes on the road, even with competition pads. As for the simple booster delete, we won't know until someone tries it and offers some feedback if it works or not!

Any mods at all to the braking system except for ADR SS brake lines are not allowed. Having said that, I would guess that over 50% of the competitive club cars have illegal mods, either wilwood calipers, proportioning valves, or larger than stock rotors. Really modifying anything in the braking system requires a lot of checking, monitoring and careful thought. If something goes wrong here it's likely to result in damage to your car, at worst it's your life.

The other option for someone with itbs / lumpy cams is to add a vacuum reservoir prior to the booster. This would be a legal mod as you're not really touching the braking system, just the vacuum pressure itself. This solves the issue of a non-effective booster, however it doesn't clear space for longer runners. Still, anyone can make one with a trip to your local hardware store to pick up some PVC piping and end caps, and then tap / glue in some brass nipples.

[Magpie]

on Madjacks's post!

I looked at all the 'stuff' to allow the ITB airbox to fit. Remote booster is not a very cheap alternative when you factor in the cost and plumbing required. A remote booster will require a mod plate again additional cost. The data I collected on vacuum available to the booster whilst running ITB's (with lumpy cams) suggests that there is more than enough to run the OEM set up.

The best option (and cheapest) is the current airbox setup. Whilst there are other ways the issue of being road legal becomes the question.

The brake setup on mine is all OEM parts from the MX5 range so no mod plate required, further I'm not running a manual proportioning valve!

Even if for just a track only car brake mods need to be carefully considered.

Remote Boosters
http://www.hydroboost.com.au/boostertypes.htm

Vacuum Pump
http://www.hoppers.com.au/brake%20kits/masters%20boosters%20brackets%20and%20pumps.pdf

[madjak]

My understanding of brake mods in WA is that any change to the braking system that the car was complied with is not allowed. So if you have a NA6 you can't upgrade to later model rotors, calipers or change anything other than the brake lines themselves. That's what the rules state, however if the modifications looks stock then no-one will know anyway so it's fairly safe to assume it won't cause an issue.

However, if you have an accident and the brakes are found to be a contributing factor and that they have been modified then you are in serious strife. Most people don't realise that there is really nothing stopping you from changing whatever you like on the car, other than cops slapping on yellow stickers. It only becomes an issue when you have an accident, and that modification is shown to be a contributing factor. This then voids your insurance and you are now 100% liable of all damages and costs, a position no-one wants to be in. Really any mods to a road car should be done with knowledge that this might end up costing you lots of money if anything with it goes wrong.

[Magpie]

For Queensland
Brakes
Replacement brakes that are offered by the manufacturer as an option for that model of vehicle may be fitted without specific
approval. For such conversions, all components must be identical to those of a vehicle originally produced with the optional
brakes.

Brake systems modifications must not reduce braking performance or increase the risk of brake failure. Brake discs or
drums must not be machined beyond the reconditioning limits set down by the manufacturer.

When brakes are upgraded using components or systems which were not standard options for the vehicle, an Approved
Person must be engaged to certify the adequacy of the new system, as issues such as hydraulic fluid sufficiency, balanced
braking on all wheels, brake pedal pressure limitations and braking performance must be considered.

For further information please refer to the LG section of the National Code of Practice for Light Vehicle Construction and
Modification.

http://www.tmr.qld.gov.au/Safety/Vehicle-standards-and-modifications/Vehicle-modifications/Light-vehicle-modifications.aspx

Looks like I will have to get my NB8B brakes certified. Sort of thanks Madjack

[madjak]

Magpie, given it's 90% a track car if anything will fail whist you're driving home from an event is probably the brakes, via a cracked rotor, boiled fluid or failed brake line / fitting / sensor etc.

Your car is so modified with other bits and pieces that the cops will have a field day anyway. For starters, any car with stickers and aero on it will be looked at severely. Your brakes, which probably look like they came on the car are most likely the least of your worries. If you balance up the risk of an issue vs how careful and how frequently you drive it on the road you can figure out how serious you need to be with certification. You can mitigate some of the risk yourself to some extent. Ie visually check the rotors and fluid levels prior to leaving an event, check the pedal before that first hard stop is required, leave ample room to all other traffic, drive like a granny. Of course if you're one that enjoys a spirited drive amongst other traffic then maybe you should get all the correct certifications as insurance.

I think the best path for that sort of vehicle, especially one that is only dríven to and from events, is to get it rally licensed. This basically gets you a pass to have it on the road, and if any cop pulls you over then it's clear that it's a race car not a street car, even if you a just driving around the block testing something before the next event. The same rules apply to liabilities as street rego but at least the rules are clear and easier to defend against in court. Ie "brakes have been changed! Of course it's a race car, but they stop fine and didn't cause the accident" as opposed to "brakes have been changed, they must be the cause of the accident, you're liable"

Only issue with rally licensing is you need a full cage (well at least in WA).

[project.r.racing]

I had almost the same setup a G's with respect to the brake/clutch to make room for the ITB's, worked a treat with the Pipercross sausage airfilter.

Note the strut brace (tool rest, arm rest or cable tie thingy) has been removed as has the Pipercross...


DSCN1867 by Eipeip, on Flickr

This one is from a 94-98 Astina/Laser.

[greenMachine]

Any mods at all to the braking system except for ADR SS brake lines are not allowed. Having said that, I would guess that over 50% of the competitive club cars have illegal mods, either wilwood calipers, proportioning valves, or larger than stock rotors. Really modifying anything in the braking system requires a lot of checking, monitoring and careful thought. If something goes wrong here it's likely to result in damage to your car, at worst it's your life.

No, worst case would be someone else is killed (IMHO anyway). Not disagreeing with what you are arguing, your point is well made.

The other option for someone with itbs / lumpy cams is to add a vacuum reservoir prior to the booster.

I have just installed one in the racecar. Not a waste of time, but not a complete solution as the vacuum levels still fluctuated and made for inconsistent braking for any but the first application after a prolonged period of no braking. Next I fitted a vacuum pump - problem fixed, solid, consistent pedal at all times while on track. I can exhaust the reservoir, but only with difficulty . Don't ask about the weight though ...

If this thread had been six months sooner, I probably would be in the middle of doing a booster delete and dual masters setup. Such is life ...

Great work madjack!

[madjak]

No, worst case would be someone else is killed (IMHO anyway).

I totally agree... Fortunately I'll be out on the track with lots of spare space around me and taking things very carefully initially. I'll check for leaks etc between runs at the same time as I normally inspect my rotors. It looks like the weather is going to be rainy / stormy, so I doubt I'll be under full load under brakes anyway. It's a bit of a shame because I really wanted to see if there was much improvement under hard brakes, but I guess it will be good to judge brake feel with less traction. A few nights ago I sat in the car and pushed as hard as I physically could on the pedal to see if anything leaked or failed, also to measure firewall flex. Nothing broke, except my ankle is actually a little sore now!

Good info on the vacuum reservoir. Was it large enough as I'm surprised the booster could use it up so fast (does it vent air or something?)

[greenMachine]

Good info on the vacuum reservoir. Was it large enough as I'm surprised the booster could use it up so fast (does it vent air or something?)

No, I checked that it held vacuum, and that leakage did not seem to be the source of the problem. Basically, I think that if the manifold does not pull vacuum on a small reservoir, it has difficulty on a big one too. That varies of course, and given enough time between applications it can recover, but sometimes the time allowed is not enough, or only enough to get, say, 50% assistance. Hence I have now fully disconnected the manifold from the vacuum supply and rely on the vac pump. So far, so good.

The pump has enough capacity to build and hold the booster and around 1-2l of vac tank at sufficient vacuum for a couple of applications, and it recovers quickly. I can hear it working over the engine and through the helmet at all but full revs. I need to move the switch (it is a switched supply only hot when the 'ignition' is on) as I can't see it when strapped in, and maybe install a warning light when vacuum is low, or a light when the pump is working. I have gone out without switching it on, leading to a hurried fumble ... always something to fiddle with err improve

[madjak]

I meant that when you hit the brakes, the vacuum in the booster must get used up and released somehow otherwise it would replenish the reservoir after the brake is released. On my car, when under race conditions, the time the engine spends in vacuum is minimal as I'm shifting fast and blipping down through the gears under brakes. I can see now how a reservoir would make little difference unless the engine is spending enough time in vacuum to build up a buffer. It highlights just how bad running a car with a booster is when you have silly cams / ITBs.

I did look at vacuum pumps as an option, but then it adds complexity and another failure point. I figured most serious race cars don't run a booster... if bigger cars can do it, a light MX5 should be ideal.

For your vacuum pump, how about a vacuum pressure switch that turns off the pump when it hits a threshold of vacuum.
Something like this but cheaper:


Ebay link:
http://www.ebay.com.au/itm/CVR-Heavy-Duty-Replacement-Vacuum-Switch-CVRVS-25-/262169589839?hash=item3d0a86784f:g:gqUAAOSwQTVWBMut