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Thread: RT142/ST141 1 brake master options?

  1. #1
    Veteran Konakid's Avatar
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    Default RT142/ST141 1" brake master options?

    Hey guys ive been trawling through the internet for hours hoping to find some information on a conversion to a 1 inch mastercylinder for this model corona.

    Ive read that an MX83 booster and 1" master works but the firewall has to be redrilled and then somehow the factory spacer plate needs to be made to work. I got mine all off atm and have purchased the MX83 setup but would rather mix and match toyota parts to do it with no drillling/butchering of the firewall. Im trying to find whether an RA65 booster fits and also suits a 4 bolt master, maybe SA63? MA61? Just can't find any info. Starting to look at hilux etc now



    The problems i have found are.

    Master cylinder: Its the offset (bolt holes aren't parallel to the ground) 2 bolt type which doesnt seem very common at all especially in a one inch. All seem to be 2 bolt parallel or the more common 4 bolt design.

    Booster: firewall pattern (4 bolt) is bigger than ke70/s13/ae86/ but smaller than MX83.

    **reason for upgrade is that i have got a YR22 Tarago F series drum rear + hydro and i now have a spongy brake pedal dude to the increase in fluid volume in the braking system. 1" should firm it up without going overboard.

    EDIT: going to go to my local brake joint on monday to see if they can match the stock master cylinder boltpattern with anything 1"
    Last edited by Konakid; 12th July 2014 at 03:49 PM.
    RT142 Estate.

    AJPS.

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    Veteran Jimmee1990's Avatar
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    If they can't match it, you could just bore your standard master cylinder to 1" and replace the piston and seals. Then it will all bolt as per normal.

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    Veteran maxhag's Avatar
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    To get a 1" Master in these cars, you use a RA60/65 BOOSTER and then you can use a Landcruiser 1" Master cyl.....

    What brakes are you using?

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    Veteran Konakid's Avatar
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    Legend! Has it been done before by someone on here?
    Last edited by Konakid; 27th June 2014 at 07:29 PM.
    RT142 Estate.

    AJPS.

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    Veteran maxhag's Avatar
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    I have a 1UZ RT142 here that has everything done.......

    If you have any questions, my housemate knows everything there is to know about modifying this chassis.....

  6. #6
    Veteran maxhag's Avatar
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    No, He it not on this forum

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    Site Supporter Javal's Avatar
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    He has RA60 / 65 front calipers and F series tarago rear drums, there's a hydro handbrake in the mix too. It's an issue that's been around for as long as I can remember, pretty much since he's had the car. The pedal comes good if you clamp off the rear brake lines, which is a good indicator the wheel cylinder piston surface area is too large for the master. I've suggested an adjustable proportioning valve to him before, placed before the hydro handbrake, but that may not work unless it's used in combination with a bigger master. I'm really not too sure on that one.

    I'd think that having a master sufficient to handle the rear drums will result in it being too big for the front calipers (as RT142 have no bias block). Fitting an adjustable prop valve to the rear circuit and fitting a master with sufficient surface to handle the larger rear wheel cylinders, then dialling it down it down to get the bias right... It may give a stiff pedal, which is better than a spongy one.

    I'd want to know whether the landcruiser master is suited to disc / disc or disc / drum and whether it uses a bias block first.

    Personally i'd just fit an adjustable prop valve first and see how it goes, because creating a restriction in the rear circuit means your fronts will do more work as the system pressure will be higher, sooner. IIRC the brake performance was great when the rears were locked off, because the rears are taking up so much of the fluid volume before actually doing much work, so by the time all of the 'slack' in the system is taken up, the pedal is half way to the floor.

    Also you'll probably need one if you go to a larger master with your brake combo anyway.
    Last edited by Javal; 27th June 2014 at 08:05 PM.
    You can have any brew you want... as long as it's a Datsun / Corolla / What is that?

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    Veteran Konakid's Avatar
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    1UZ RT142, thats what i should of done with mine.

    Thanks man ill be in touch, will sus it out to see if the MX83 1 Inch master bolts up to a ra60/65 booster when i get one.
    RT142 Estate.

    AJPS.

  9. #9
    Veteran Konakid's Avatar
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    Yeah good idea josh. Ill get a wilwood one and put that in the same time as i do the master upgrade. rather have a hard pedal than a soft one as you said!
    RT142 Estate.

    AJPS.

  10. #10
    Site Supporter Javal's Avatar
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    Do the bias valve first. You will likely solve your issue and have normal pedal effort.
    You can have any brew you want... as long as it's a Datsun / Corolla / What is that?

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