Larger Master Cylinder conversions?

cisco

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Has anyone found that maybe a pulsar master cylinder is a straight swap in? Or had their micra one's valve largened?

I'm getting sick of the spongey pedal feel due to having the large AD22VF brakes installed with the factory master cylinder. As the pistons are much larger, the pedal has to move a lot more to inject the required amount of fluid.

A factory micra has a much firmer brake pedal feel.

If noone has done anything in this area, I'm going to see what some options might be soon. Really want to get that firm pedal feel.

Also going to get my ABS completely removed. I'm not running any front sensors any more since I installed the VLSD driveshafts, now the ABS light stays on. So today I will pull out its fuse so that goes away, but the unit and system is very heavy, so I want to remove the whole thing and gain a whole lot of clean engine bay room and weight saving.
 

cisco

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Haha damn I just tried it and found that out :)

Yeah derr. Just makes the light come on earlier.

At least with the sensors off the shafts it doesn't come on until you're doing about 20kmh and it realises heh.

Yeah dunno mighty. I've had mine bled and all the fluid replaced etc, and although they work great, there is just too much pedal travel. Shortcake's is much less. Its bound to happen when you go to larger pistons and don't change the valve in the master cylinder to push more fluid. I should see how yours feels one time to compare, maybe there is some other difference with my car having ABS.
 

CMF_NotAnotherSSS

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I don't know if its just me, but i seem to recall the ABS equipped micras having much softer brake pedal action.

(from the few I've test driven over the past few months anyway)

I know its the same with the pulsars with ABS as well - the non ABS cars have MUCH tighter brake pedals.

Are you running braided lines cisco?
 

cisco

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Probably one other good reason to remove the ABS, however s-shortcake has ABS and its pedal is firm as..

Its definately proven though that adding monster piston brakes and keeping the same master cylinder valve will mean more pedal travel. That's what my car is doing.
 

CMF_NotAnotherSSS

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What type of ABS system does your car have and what does shortcake have?

The troublesome Lucas set up or the half decent bosh?

I drove a december 95 super s with a lucas abs system, and it sucked. It was a really crap abs system and the pedal was really spongey.

BTW, do you loose brake fluid at all? I wonder if you have a crappy master cylinder? Did the ABS work properly (and not interfer with normal driving) before you removed the sensors?

Are all brake booster vacumm lines hooked up and not blocked or broken?

I'm just wondering if there's an underlying problem with your current brake set up.
 

cisco

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Both cars are the Lucas system.

Yeah it works perfectly when it was hooked up. Didn't honestly interfere with normal driving. Sometimes around a corner when you were moving fast and on the brakes when the weight was off the inside wheel, you could feel the ABS just start to control that wheel, but that felt useful and you had to be moving a bit.

Weird. No I took my car to a brake place and got them to change the fluid and bleed the system. Weird!

No braided lines. From everyone I've spoken to, they don't do much. Especially not enough to stop this much pedal play :) Even the brake shop told me that they will do a bit under extreme driving conditions, but its nothing to hang your hopes on.
 

CMF_NotAnotherSSS

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Yeh, they are alot of money for not an awful lot of difference. If mean if you've got the spare dosh, why not... But on a small car like a micra, i doubt they would do much, i was just wondering if you had them or not. :)

So both your cars have the lucas system? What year and month were they built?

I'm struggling to figure out why nissan has used bosh and lucas systems on the micras.
 

CMF_White Knight

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THis is interesting. On Family Hack the brakes are fine. Firm,responsive, progressive.
White Knight a different feel. More spongy.
Both have had Pulsar brakes fitted to the front and both rear drums.
Will change the brake fluid on White Knight and see if it improves.
 

cisco

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Which cars did you see the Bosch system in? Later model
Super S or something?

Both our Super S's are June 1995 models.
 

CMF_NotAnotherSSS

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Okay here we go. If a member with a Super S drops by this thread, please post what month and year your micra is and what ABS system it has.

June 95 - Blue Monster and Shortcake - Lucas.
July 95 - no_jammn' - Lucas. (my bad, i thought it was bosch)
December 95 - Random micra - Lucas.

So its only one super s ( a series 2) which had the bosch system
 

cisco

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Hmm primera master cylinder hey. Thanks.

That sounds like the way to go. I might check out if some aussie pulsar ones might fit in.
 

CMF_Alex_B

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June 95 - Lucas

just a FIY when i fitted my N14 2.0 brakes i bled them with a one man bleeding kit and notice spongy pedal like the vacuum boost wasn't working or something, cause when the car was off is was spongy on the first press and then on the second - but when it was on it was spongy every press of the pedal > wouldn't firm up. Soon after coming back from canberra and trying seano's car, i read the haynes manual for directions on bleeding and followed them exactly using >two people< = no spongy pedal, brakes feel say at least 30% and almost 40% better than before 'on light touches>firm touches' but only say 15% better on heavy braking. i was amazed the difference it made. Also someone once told me that brake fluid absorbs moisture and after 1-2years is no good, so maybe try pumping through a brand new bottle or two of fliud (don't use the old half empty one or buy any that looks like its been sitting at the shop for some time)

Alex
 

CMF_LWC

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Did you rebuild the bigger calipers with new piston seals? If they stick a little in the bores it could hold the pistons back in the bores a little giving longer pedal travel and spongy feel. Need to keep them absolutely clean during rebuilding, too.
Also, when you bled the brakes did you do front and rear in the right order? Shortest to longest pipe length to push all bubbles from the front to the rear and then out.
Bleeder tube needs to be kept below the surface of the fluid and the master cylinder topped up at all times during bleeding. :)
 

CMF_NotAnotherSSS

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cisco - here's an idea.

Why dont you manufacture something to secure the master cylinder or make something which strengthens the firewall around the master cylinder?

That might help your pedal feel... (infact in a car like a micra i bet it would help)
 

CMF_NotAnotherSSS

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Quote: "Its basically an L bracket attached to the strut tower with a bolt that pokes out against the master cylinder, stops it flexing away from the firewall."

A bought one looks like this : http://www.perfectrun.com.au/real_image/brake_image/CUSCO BOC.jpg

Explaination: "Imagine when you push on the brake that its pushing straight into the master cylinder (thats not quite how it works, but the direction is the same). So it flexes away from you (firewall) and loses some compression in the process.

As I said, some cars are worse than others, it's not a model specific problem."

Seems intelligent to me.
 

CMF_NotAnotherSSS

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Well i've been googling, yahooing (the internet sort) and altavistaing all morning.

Could find a single mention of a brake booster holder or firewall stiffener for the K11.

I think theres a nismo item for the k12, but the page was scrambled.
 
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