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Dan260Z

Brake and wheel options to keep VASS engineers happy...

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Thanks for all the assistance guys.  Thought I'd add an update of where I was at since last posts...

 

Ended up writing up a plan for the whole car - covering Brakes, body, suspension, wheels, tyres, engine change, trans - you name it - and detailing what I planned to do for each. 

With each proposed mod, I checked out the rules in VSB14 http://www.infrastructure.gov.au/roads/vehicle_regulation/bulletin/vsb_ncop.aspx

And made sure whatever I was planning fell within these rules.  I also tried to reference the rules from time to time within my plan to provide justification to the engineer.

 

Sent it to a few engineers to get their impressions and see who appeared to be the most reasonable (inc Paul Bottomley as suggested).  Only ever got a reply from one guy - www.bonneville.com.au.  He was impressed with the plan - basically said everything was ok, pointed out a few areas where he might've needed more detail or a small change, but otherwise was happy to let me go ahead after an initial inspection, with the instruction to simply call him when it was all done (and run any deviations from the plan past him along the way), for a final inspection, brake and noise test.

 

A few points I remember that might be of use to soemone looking to mod their zed legally (with engineers approval):

 

Brakes: Rear - Happy with the MM brackets, S13 or S14 calipers.  Front - concerned about master cylinder sizing with the hilux S12W's  (I proposed to use a 15/16" 280zx master in my plan).  A little investigation found that the hilux used a 1" master - but worse still - many folks on one of the forums I found (don't ask which, too long ago now) complained of excessive front bias with that setup!  I ran a few calcs and found that the excessive front bias comes from the large increase in piston area when using the hilux calipers.  So now I plan to run Volvo 240 4-pot calipers over the 300zx rotors, using a custom steel bracket (yet to be run past the eng) as they have roughly the same total piston area to the stock zed 2-pot and are design for a 20-22mm disc (and were in production for 20 years so lots of pad options and spares).  This will be combined with a bias adjuster in case I get too much rear bias.

 

Engine:  all good in this dept, since the plan is to run a bog-stock RB25DET with all the factory electronics, sensors, etc.  His main rules were "nothing to vent to atmosphere, and no gadgets please". And to check clearance to bodywork, etc.

 

Wheels/rims:  Found that according to VSB14, 245 is the widest tyre allowed, based on 1.3 x 195 (stock width).  Wider if I can prove zeds came out from factory with wider tyres - good luck finding the paperwork.  But I'm more than happy with 245's.  Rim width is then based on the tyres size - I recently bought some XXR 531's in 16x8, +0 offset.  I'll need to check the track width with them fitted to ensure I don't exceed +1 inch over 53"rear and 53.3" front.  Should be easy as mine seems to measure well below 53" with the stock 5.5" mags. 

 

Seemed to be happy with other mods - flares, custom light panel for the rear (using ADR approved lights), King "low" springs, urethane bushes, aftermarket track rod (providing it used a rubber bush - no heim joints, etc), removal of the rear bumper, aftermarket seats with custom mounts (providing he likes the mount design, and the seats are ADR). Wanted to see the seat belts replaced with inertia reel types (front at least, pref rear too).  Also concerned with tailshaft mods - I suggested fitting a safety loop which seemed to ease his mind a lot.

 

Anyone else thinking of going the engineering route feel free to ask questions - I'm not qualified in any way to state what's ok and not ok - but I'm happy to let you know what I did and how the engineer took it.

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Hey mate.  Great plan, you seem to have been very thorough.  In regards to the Hilux brakes, from my experience and from other people I have spoken to, the 15/16 MC is plenty, infact the 1 inch was too much (remember Hilux have bigger rear brakes).  Food for thought

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I have read on hybridz that John C states that Installing just the fronts with the 4x4 hilux (Vented or not) does make the bias to much to the front.

 

I found this article online and if you do the math he is correct. My setup on the track car will be 4 pot fronts and 4 pot on the rear.

 

Here is the link

http://acceleratingperformance.blogspot.co.nz/2011/05/master-cylinder-math-explained.html?m=1

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I'm not disputing that, but wouldn't using similar sized brakes from any car on the front have the same affect?

correct it is all about the bore size, both pistons and mastercylinder, then the ratio of these front vs rear that setups up the bias. Of cause most of the issue can be corrected with a bias/proportioning valve or using dual mastercylinder/balance bar setups.

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Yeah so I am not sure if the Volvo brakes would change anything but I doubt they bolt on like the Hilux ones.  So maybe the Hilux calipers and a brake bias adjuster install?  Not sure what the engineer would have to say about the bias adjuster.

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Not sure of the bore size of the volvo but the 4x4 toys are 44mm or 41.3mm depending on the model there is one with 2 different size pistons.

 

As for mounting I believe the volvo is metric 90mm vs the 88.9mm or 3.5 inch on the zed. So close enough that they fit with a small sleeve. The other issue is the volvo is a dual line fail safe setup so a connecting line needs to be built so a single line can operate the pistons correctly.

 

 

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Yeah mounting the volvo items will be an issue - the ones I have are 76mm bolt spacing.  Plan is to make up a steel bracket to adapt it, but it depends on what the engineer says.

 

It comes down mainly to piston area.  The Stock zed 2-pistons yeild a total of 3.535 sq-inch.  The hilux 43mm 4-pot yield a total of 4.48 sq-inch - a massive increase which results in a master-to-caliper piston area ratio of around 17% which is closer to a non-power assisted ratio (very rough rule of thumb which doesn't acount for pedal ratios, etc I know).

The Volvo 240 caliper has 38mm pistons and thus yields a total of about 3.5 sq-inch.  so all other things being the same, it should result in similar clamping force for a given amount of pedal pressure to the stock brakes, albeit with a bigger pad area and more even pressure application across the pad. 

 

Not sure how the MM 240sx rear set up compares since I don't know a lot about drums and thus can't relate them through my dodgy maths :-P  but I figure if I reduce the front bias by using the volvo calipers over the hilux ones, then worst case I'll end up with too much rear with the 240sx set up - which I can dial out with a prop valve (the engineer was ok with fitting one providing it couldn't be accessed from the driver's seat).

 

Apparently the S13 and S14 calipers were 35 and 38mm respectively - which also allows some options for obtaining less/more rear bias later down the track if I find I have excessive rear bias outside the scope of what a bias adjuster can tune out.

 

Found the thread btw where people were talking about the bias issue:  http://forums.hybridz.org/index.php/topic/103856-need-help-with-240z-brake-bias-with-4-piston-toyota-and-240sx-brakes/

 

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NZeder - you mentioned you thought the volvo calipers were 90mm spacing - perhaps this means there were some made with that spacing as opposed to the 76mm ones I have sitting round - where did you find that info?  If I can avoid making a bracket it'll be awesome - although I'd still need to check centering over the rotor, etc of course.

 

Not too fussed about the twin circuit set up - I'll just run a splitter at the caliper.  Else another idea I've seen done is to drill a hole between the bores behind the pistons, and block off one of the holes. 

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I found that on MG forum...so only internet hearsay.

 

My road zed has 4 pots front that have 38mm pistons for the same reason you are working on and on the rear 38mm two pots. Not sure what the feel is like as the car is still a work in progress like the track 260z too :( need to win the lotto so I can have time in the shed and not in the office - that way the weekends will still be occupied by taking the kids to their sports and time at the track not doing the lawns, house hold stuff :(

 

There are some other iron calipers from a Rover SDi V8 that is a 4 pot and MG Metro the MG guys go on about too along with the Toyota 4x4 items so I think the MG guys have found the same issues with the bore on the 4x4 too large without balancing the rears to match.

 

What model volvo calipers have you got?

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Have you thought about getting some of the dust booted Wilwood Dynapro radial mounted calipers? They do a 1.5 piston 4 pot to suit  0.81" aka 22mm or 1" 25mm rotors and that has 3.54 piston area.

 

As they are radial mounting that is easy and gets around any lug/ear issues they are dust booted which is a requirement in OZ? have a 100mm long pad. The calipers I have are basically the same but came from the UK as these Wilwoods were not around when I was looking for the setup on the road car.

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Mate, I feel your pain! Got some very young ones at home myself so I'm usually lucky if I get 3-5hrs work in on it every other weekend.  I think I spend more time on the net planning it or dreaming about it than I do working on it.

 

Interesting...how do the radial mount ones go onto the zed?  I understand radial mount calipers, but do you run a special bracket to adapt the stock mounts to radial?  Is it something I can buy off the shelf somewhere or did you have to make it?

 

 

I'd previously only found these in Wilwood's dust-booted range:  http://www.wilwood.com/Calipers/CaliperList.aspx?appl=&subname=&dustboot=Yes&numofpist=&mtspec=5.25" Lug Mount&pistarea=

I'm still considering making my bracket up to use these instead of the volvo jobs, but I can't see my road Zed benefitting all that much from a kg or so less unsprung weight compared to the volvo job, and the wilwoods will cost more initially ($350+ vs $60 for a pair of volvo's), pads will be harder to get and probably more expensive, etc.  That said, it remains an option.  I'd certain consider a wilwood if i found one that had 90mm mounts and dust boots as it'd save me making a bracket!

 

 

Yeah dust boots are a requirement in OZ.  Engineer did mention he'd prefer to see them.

 

 

I'll do some googling on the Rover calipers when i get a moment too, thanks for the tip. 

 

90% sure these are the volvo calipers I have, the part number on the caliper "320029" rings a bell... http://www.autopartswarehouse.com/details/QQVolvoQQ240QQA1_CardoneQQBrake_CaliperQQ19901991QQA119429.html

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I'd previously only found these in Wilwood's dust-booted range:  http://www.wilwood.com/Calipers/CaliperList.aspx?appl=&subname=&dustboot=Yes&numofpist=&mtspec=5.25" Lug Mount&pistarea=

I'm still considering making my bracket up to use these instead of the volvo jobs, but I can't see my road Zed benefitting all that much from a kg or so less unsprung weight compared to the volvo job, and the wilwoods will cost more initially ($350+ vs $60 for a pair of volvo's), pads will be harder to get and probably more expensive, etc.  That said, it remains an option.  I'd certain consider a wilwood if i found one that had 90mm mounts and dust boots as it'd save me making a bracket!

 

You will be suprised how cheap the pads for Wilwoods are. For the dynalites they can be had in many compounds for $80 a set delivered from the States.

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