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Discussion Starter #1
As many of you might remember I joined this forum with an interest in adding an Eaton M90 supercharger to my Xtrail here in AUS.
Well 2018 may be the year so I thought I should start this thread in the correct section.

The M90 is still new in it's box in the garage, checked just a day ago when I showed it to my 15yr old son. His reaction was priceless.
on Flickr

I have also recently purchased a full front/rear set of 300zx calipers to hopefully do a full brake upgrade during the process, for which I have used a lot of information from this forum and a couple of particular members.
on Flickr

Current plans are to start by doing an engine rebuild because the QR is down on power and using too much fuel so a "stretched" timing chain is suspected. After 192k kms (120k miles) I think it is probably due one anyway, especially before the M90 addition.

Anyway, feel free to add encouragement, helpful hints & tips or suggestions as I go.
 

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Discussion Starter #5
OK so the new (used) calipers have arrived.
Checking the dimensions before, I knew I would more than likely need spacers for the front wheels, but now that I have checked with all the relevant design rules here in AUS, it seems spacers or adapters are illegal :(
The handbrake (read wife) won't like me getting new rims so the standard rims will have to fit somehow.

But I may have a possible solution...
From my measurements it seems a 15mm spacer (read hubcentric adapter) will be needed.
A thought I had is to put the adapter onto the hub and then fit a rotor with a deeper hat over the top so that from the outside it looks like the wheel bolts directly onto the studs with no spacer.
So for my standard 280mm Dia, 49mm high, 28mm thick, 5 lug standard Xtrail spec rotor with a 68mm hub hole, I can find a 276mm Dia, 64mm high, 28mm thick, 5 lug Mazda spec rotor with a 72mm hub hole.
The 4mm less rotor dia doesn't bother me and I know I can get hubcentric adapter rings made for the 72mm down to 68mm for the hub hole.

What I would like to know from all you learned people is if having the adapter under the rotor between it and the hub would be better or worse than having it ontop of the standard rotor between it and the wheel.
 

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Discussion Starter #6
I forgot to add...
Don't be afraid to PM me about any ideas with this mod rather than post it in here. I'm after negatives as well as positives.
Many of you guys run with spacers so they can't be a bad or safety compromising thing. I'm just looking at doing it a different way so they aren't so "obvious".
 

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I'm running 15mm spacers, and have been for years. I use the 2J extended wheel studs (82mm I think, the long ones) and do tend to change the lug studs every year or so, speaking of which, its coming up again soon. I dont reuse them when I swap wheel hubs. Speaking of which again, its about time to flush my brake and clutch system for the year as well.

the only real issue I can see in installing the spacer behind the rotor, would be getting the caliper lined up with it. if you can find one deep enough, it would probably work. what may be a concern, and I havent really thought it thru to decide if it would be, is you are placing the brake load further out on the studs, rather than right at the hub. longer lever arm as it were, stronger studs and a higher torque value might be in order to keep everything tight under hard braking.
 

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Discussion Starter #8
The hub centric adapters I am considering are like these
on Flickr

So the adapter bolts direct to the hub studs and the rotor bolts to the adapter studs. The respective braking forces will be at the bottom of the adapter studs from the rotor and then transfered directly to the bottom of the studs on the hub.

If I was using extended studs on the hub and just placing a spacer ring over them under the new extended rotor, I get what you mean by the braking force being further along at the centre of the stud and potentially being weaker.
 

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The hub centric adapters I am considering are like these
on Flickr

So the adapter bolts direct to the hub studs and the rotor bolts to the adapter studs. The respective braking forces will be at the bottom of the adapter studs from the rotor and then transfered directly to the bottom of the studs on the hub.

If I was using extended studs on the hub and just placing a spacer ring over them under the new extended rotor, I get what you mean by the braking force being further along at the centre of the stud and potentially being weaker.
unless they are made of good steel, dont get those, please

cheap_spacers2-large.jpg
wheel spacer failure.jpg
20151002_122023.jpg
 

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Ouch :eek:

GKtech seems to be a trusted well-known brand for these types of adapters.
Suppliers here in AUS as well as US/Canada.

I would never consider any china knock-offs for these safety related items.
honestly, I would still think it would be safer to go with longer studs and use the kind of spacers 2J sells, IMHO that kind of spacer is introducing stress points that can fail. and usually at the worst times. I personally wouldnt run them, but then again, pushing over 400 hp I tend to get a bit picky
 

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i'm not comfy with this idea

i have broken studs
like 4 or more

yeah, going around corners at yogi speeds

i change front studs often
they really do break
DSCN1542 by Barry Belgard, on Flickr

frequent changes allow the most recent developments too
these are used by nissan racing as well as 2jr, note rounded tips on newer versions
20171004_162139 by Barry Belgard, on Flickr

moving the wheels out
increases tq steer, and tramlining
increases loads on wheel bearings, struts and other suspension pieces

i have used spacers in the past but never more than 5 or 10mm
rotorgood by Barry Belgard, on Flickr


moving the rotors out?
most spacers lack true machined surfaces, hard to eliminate rotor wobble
shanover covered the rest

if i'm illegal anyway why not use the safest possible route
imo mount the spacers normally[hard to see anyway]

spacers take increased checks on lug nuts

no matter how good the machining
they will move on their mounting points
note clean surface on install
DSCN1643 by Barry Belgard, on Flickr

a few yogi runs
20170811_130338 by Barry Belgard, on Flickr

then a sort of polishing takes place
100_2315_zps90d638c4 by Barry Belgard, on Flickr

so in doing this i would prefer the spacers that are small
well machined,
and mounted in their normal place


in addition
use extended racing hardened studs,
changed at least every two years, [by season if racing]

and checked and torqued at least weekly
imo


btw
speaking of polishing
my stage and launch antics often polish the rear rotors
toolinplace by Barry Belgard, on Flickr
 

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Discussion Starter #14
...in installing the spacer behind the rotor ... what may be a concern, and I havent really thought it thru to decide if it would be, is you are placing the brake load further out on the studs, rather than right at the hub. longer lever arm as it were, stronger studs and a higher torque value might be in order to keep everything tight under hard braking.
Wouldn't the shear strength of the studs would be the same near the base as it would be part-way along the stud with it fully threaded ?

What I compared this to was the tailshaft extensions you see for 4WDs that have suspension lifts and they need a spacer between the drive flanges to make up the added length.
To me, the application would be much the same with a rotational force being transmitted from one plate (hub) through a bolted spacer to another plate (rotor).

Granted longer, higher strength studs are a must.
 

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Wouldn't the shear strength of the studs would be the same near the base as it would be part-way along the stud with it fully threaded ?

What I compared this to was the tailshaft extensions you see for 4WDs that have suspension lifts and they need a spacer between the drive flanges to make up the added length.
To me, the application would be much the same with a rotational force being transmitted from one plate (hub) through a bolted spacer to another plate (rotor).

Granted longer, higher strength studs are a must.
I am talking about the shear force on the studs, the weakest point of which is normally right where the stud is flush with the hub
Stud_01.jpg
Most lug studs will break as in the above picture. Depending on the brakes power, it will usually slow the vehicle down, faster than the engine can accelerate, so the shear forces will be greater, when the rotor is spaced farther out from the hub. granted, it will only be 15mm, but thats significant when you are talking about the shear stresses. While the wheel/spacer/rotor/hub are all held together by the clamping force, there will still always be some movement as the wheel brakes or accelerates. You can see the results of that on the surfaces that mate, in that they will look polished compared to the surrounding surfaces. If the studs are strong enough, it would probably never be an issue, or even to drill the hub for the next larger size stud assuming that the wheel bores will fit over it. Most people dont realize that bolts work by stretching. it is never a 100% solid connection, and as power is applied, the bolt stretch will continue, and will return to normal as the forces are relaxed.

Hope this made some sense, havent had my coffee yet!
 

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I'm not sure what I think of this idea. I'll mull this over a while in my head.


At first I think fuck no way....
But then idk....and need to think about it.


My main concern is the material that actually would be holding the studs that would be holding the rotor.
If you used extended studs and 2j style spacers then at least your hub would still be what secures the studs and not spacers. Spacers don't seem to be made of anything near as strong as our hubs. IMO


I'll try and find time to think more on this and post back later.
 
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Now that I have had coffee, and worked ten hours, behold my awesome mspaint skillz!!!!~!
spacer.jpg

couple of notes
1. Not to scale! obviously
2. this is for the rotor only, the effect on the wheel itself would not change
3. the leverage point would be in reverse rotation to the tires, as the brakes will be slowing you down.
4. no laughing at the old farts drawings!!!

This is also assuming that you are not using the type of spacer you showed at first, with the built in lug studs, please dont use those, lol
 

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I have a question. And it's a question because I don't know the answer and not a question for arguing. (Yes I know the drawing is not accurate. Is not why I ask. Just don't know)


Is the spacer actually smaller diameter than the hub?
I am not sure the size comparison.

Obviously the hat is larger diameter than the hub.


Regardless I don't disagree. And I don't think I would this.

Studs do tend to snap where they are not press fit. Assumingly because that's where they have room to wiggle and weaken. And the only place they are press fit is in the hub.


There's gotta be some other way. Or the way is just to get new wheels. Or to swap your brakes every time inspection comes up for the car :lmao: ;)
 

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this may seem off topic but i feel its relevant
recently got a ride in a 300 plus wheel hp honda r

this is a very impressive engineering feat for high power fwd cars

they have moved the brakes [caliper and rotors, ] in further toward the center line
the results are worth checking out for your self

just the opposite of what your doing


hard to see here
brakes and wheels overlap hub
20171106_131332 by Barry Belgard, on Flickr

we are going to see this approach on every new high power fwd car in the future
imo

my hats off to Honda
but i'm not buying one
 

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in Shanover's diagram above there will be movement, vibrational affects, at each junction of parts
facilitating breakage at several hard sharp points

in addition the closely pressed parts of different metal origin, will facilitate the generation of electric currents speeding corrosion
at every interface of different metals
not helpful

also moving rotors and calipers outward may induce tq steer even with braking
and more radical pulling to one side with the loss of traction by one wheel

in the end i asked myself would i do this?

of course i would

but then take a look at what i choose to do in the past
don't think i'm the best example
 
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