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Help! What brake options are available for S30 Z cars?


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And a new option for the front.   R32GTST front rotors (280mmx26mm), centre hole machined out to match the 260Z/280Z hub, diameter reduced to by ~ 5mm with Hilux S13W calipers. The caliper

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I have a 240 that was allready converted to disk and I am swaping the setup into a relatively rust free 280 chassis, all the hardware swaped with a little work , the conversion used stock front 240z rotors and calipers in the rear.

My question is reqarding the stock master cylinder since it was originaly set up for drums in the rear, should I remove the check valve on the rear output ? I know that drums require more residual pressure than disk do and I have had experience with this on other vehicles , it caused the rears to lock up and not release since the check valve held the pressure , has anybody addressed this issue with Z cars ? I have searched FAQs and found nothing regarding the residual pressure valve , can anybody answer the question or steer me in the right direction ?

Edited by bobzzzz
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I have searched FAQs and found nothing regarding the residual pressure valve , can anybody answer the question or steer me in the right direction ?

 

Search "Proportioning Valve" or Prop Valve" instead... you should be able to find lots of info. Be aware that the 280Z and pre '73 240Z's have very different proportioning valves and the plumbing is consequently different as well.

 

Nigel

'73 240ZT

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The proportioning valve is not the issue , I bypassed the front passenger side line going into the proportioning valve with a 240z brake line and the rear line will be going through a adjustable proportioning valve instead of the stock one so I have that part covered , I just want to find out if anybody that is using a stock master cylinder with rear disks has done any modifications to the master cylinder reqarding residual pressure like removing the check valve or something.

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The proportioning valve is not the issue , I bypassed the front passenger side line going into the proportioning valve with a 240z brake line and the rear line will be going through a adjustable proportioning valve instead of the stock one so I have that part covered , I just want to find out if anybody that is using a stock master cylinder with rear disks has done any modifications to the master cylinder reqarding residual pressure like removing the check valve or something.

 

I misunderstood what you were asking. My apologies.

 

Most people that have a rear disc conversion have also already upgraded the front calipers and switched to a 280ZX master cylinder for the larger volume. The ZX MC is of course, already set up for rear discs. So your situation isn't all that common.

 

Nigel

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Thank you for the info, I was considering using a M/C made for 4 wheel discs from a ZX , I just couldnt find any info on using the stock 240 60 or 80z M/C ...except that some people kept the stock M/C with the rear disc conversion , if they used the stock M/C did they remove the check valve ?

I will most likely change the M/C and solve this issue but for now I was looking for a residual pressure valve I could remove and make it work , the diagrams show a check valve on both front and rear outputs so I was thinking I could swap the check valve from the [i have a extra M/C] front disk output into the rear drum output so both the front and rear have the check valve used on the disks...Make sense ?

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I will most likely change the M/C and solve this issue but for now I was looking for a residual pressure valve I could remove and make it work , the diagrams show a check valve on both front and rear outputs so I was thinking I could swap the check valve from the [i have a extra M/C] front disk output into the rear drum output so both the front and rear have the check valve used on the disks...Make sense ?

 

The Nissan rebuild kit I had for my ZX MC included check valve parts for both a rear disc and rear drum setup, depending on what you had. It's been 10+ years since I did that rebuild, but from what I recall, the only difference was a rubber nipple looking thing. I'd like to say that the rear disc nipple looked the same as the front disc nipple, but I don't recall for sure. But it seems reasonable that you could take a front disc check valve setup and install it in the rear line of the MC. Hopefully, someone else can chime in on this.

 

Nigel

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Thanks for the info , best info I found yet ....but I may have gotten lucky I might already have the right M/C to swich to rear disk but I want to make sure, does anyone have a picture of the ZX M/C for 4 wheel disks ?....the one I have is a nabco 15/16

I looked already but I only found the pics of the nabco 7/8 for the 240z

Edited by bobzzzz
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  • 2 months later...

Great write up on the possible conversions for all of us. Too bad I found it a year after I did the non vented rotor configuration since I wanted the vented one. Stopping power is a huge step up from the stock caliper and rotors on my 77 280z but still far from great.

 

I'll have to make the change when I can afford wheels.

 

Thanks again for the great write up!!!

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  • 2 weeks later...

Hi, I've been inspired by this thread to improve the front brakes of my 240z.

 

I bought rebuilt toyota S12+8 calliper that are supposed to be for the toyota 20mm thick vented rotors (it's the toyota ref 47750-60021 for 1981 to 1989 J6 landcruiser). I think I may have received the wrong type of calliper from the seller because the width between the two parts of the calliper is 20mm, and I can't fit the 22mm thick vented rotor in it. Here is a picture of the width I am talking about in case I am not clear (it's not the picture of the actual calliper but one taken from post#6).

 

202780s128question.jpg

 

Can anyone tell me if it is the S12+8 vented or S12+8 solid? What is this width for solid and for vented rotors? Do I have to machine the S12+8 vented to let the rotor get in the calliper?

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  • 4 weeks later...

I have read the thread and there is all kinds of info here. In reading there seems there may be a possible solution for me, going with 14" wheels, but I am having trouble pulling it together.

 

Here's the deal. I have 1970 240 and I have 2 sets of 14" wheels: #1 14x7 iron crosses, #2 14x7 Enkei. I am feeling vintage, so I HAVE to stick with these wheels, man! I am a DD and I will TrackDaze 6 weekends this year, as well as ZCON. I need to get the best performance out of my brakes, front and rear, for this use.

 

  • What are my options for front disk brakes?
    • Vented/slotted/cross-drilled rotors?
    • Caliper upgrades?

    [*]What are my options for going disk on the rear brakes?

If it doesn't come together with rear disk brakes and a front disk upgrade, it looks like I will have to go with better pads/shoes, perhaps perforance rotors/drums, and call it a day.

 

Thanks.

Edited by reefedjib
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  • 1 month later...

I haven't read this thread in entirety so I don't know if it was mentioned, but could you technically take the S12+8 Toyota Calipers meant for the solid rotors, grind out that gap and fit the larger vented rotors? Unfortunately I purchased the earlier ones for the solid rotors before I saw this thread.

No you can't, you would have to grind about 10mm on one side of the calliper gap, your grind would end to be assymetric because it is currently centered for the solid disc, you would also need extremely thin brake pad on this same side to do this, , so a normal pad on one side and .

 

You should better sell those callipers and buy the proper one, it's the simplest solution. Or if you really want to modify these callipers, you could split the calliper in two and add a custom made spacer in between the two parts of the calliper to get the right gap for the disc.

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I have read the thread and there is all kinds of info here. In reading there seems there may be a possible solution for me, going with 14" wheels, but I am having trouble pulling it together.

 

Here's the deal. I have 1970 240 and I have 2 sets of 14" wheels: #1 14x7 iron crosses, #2 14x7 Enkei. I am feeling vintage, so I HAVE to stick with these wheels, man! I am a DD and I will TrackDaze 6 weekends this year, as well as ZCON. I need to get the best performance out of my brakes, front and rear, for this use.

 

  • What are my options for front disk brakes?
    • Vented/slotted/cross-drilled rotors?
    • Caliper upgrades?

    [*]What are my options for going disk on the rear brakes?

If it doesn't come together with rear disk brakes and a front disk upgrade, it looks like I will have to go with better pads/shoes, perhaps perforance rotors/drums, and call it a day.

 

Thanks.

 

Pretty much my circumstances, too. '70 Z and I wish to run old school 14 inch mini mag copies and another set of kidney cut alloys.

 

I have the MM rear disk brake kit using the 240sx calipers. They just barely clear a set of 280zxt stock alloys. They clear the kidney cut alloys, and will clear the minimags ONLY after grinding portions of the caliper and running 1/4 inch spacers. The issue is back spacing and width of the wheel. 6inch will work, 7 inch wide requires spacers & light caliper grinding.

 

I have all the parts to convert the front to ventilated front disks with the Toy calipers. I understand this combination is a bit of overkill up front when combined with the MM rear disk brake conversion. After reading every possible thread on this site and others, I think I will keep the stock front datsun solid discs with the Toy calipers for solid rotors. The Toy calipers have more pad area then the datsun stockers. I am running a larger datsun MC which I believe to be 15/16ths in diameter. The proportioning valve, which is located in the back, is gutted and a new proportioning valve mounted up front.

 

The ventilated Toy caliper/rotor swap is quite heavy and I understand that many folks have had difficulty in balancing the braking forces between the Toy ventilated rotors/calipers up front and MM disk conversion in the back. I hope to avoid a balance problem by sticking with the stock datsun front rotors with the 99.99% bolt on Toy solid rotor calipers.

 

This car will be a DD and will, most likely, never be on a track other than, perhaps, 1/4 mile drags.

 

tongue.gif

 

g

Edited by zgeezer
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Arizona Z car kit

 

Description: Arizona Z car makes a complete conversion kit using Wilwood 4 piston calipers and curved vane rotors. Recommended racing use only. This kit features 4 to 5 lug conversion, new aluminum front hubs with bearings. There are also optional 13" brake kits with SIX piston calipers. Their products are listed here: www.arizonazcar.com

 

Why do you say that this setup is recommended for racing use only?

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