RotorMotorDriver

iTrader: (1)

Wheel studs commonly used to convert from the wheel bolts we have to wheel studs are 2 1/4" long with 12x1.50 thread, but I dont know if that helps or not.

~T.J.

EDIT: Of course it helps, he just needs to know what size hole to drill in the rotor He just needs to drill holes and tap them for 12x1.50 in a 4x114.3 bolt pattern, or even 5x114.3 if so desired.

As for someone who asked if it opens up more possibilities for wheels by going to the 4x114.3 - lets just say a lot of Hondas have that same pattern...

Also, someone said multiple patterns in rotors would be unsafe. I disagree. They make LOTS of wheels that have multiple patterns in them, as well as driveline flanges and other items. Rotors wouldnt be any different IMO.

For what its worth, Im interested in this as well. If I could get a set of 12A rotors but custom drilled to 4x114.3, Id be all over that like a fat kid on a candy bar.

evil_motors

iTrader: (3)

yeah seriously hurry with the answers i want these sooooo bad

dj55b

iTrader: (2)

Can someone clarify to me how the rear ones would install? Wouldn't you have to change your back axle? Cause if I remember correctly, the studs go through the wheel, and the rotor (the rotors on the back only have hole and no threads) and then bolts onto the axles or am I wrong?

laundryhamperman

iTrader: (3)

I want to agree with that last comment about the rear axle. From what i remember, my axle has the studs and nuts on it, but the rotors aren't on it yet. This could create a problem.....

evil_motors

iTrader: (3)

so how is the rear rotors held on then.. that would be the question to ask.

vipernicus42

iTrader: (4)

On the stock FB the rear rotors are held on by the bolts which go *through* the rotor and actually screw into the rear hub (for lack of a better word). In order to go 4x4.5" on the rear you'd have to re-drill or replace those as well. You could probably get a set off a GSL-SE, but if you're pulling axles, then why not pull all the brake-mounting components.

As for the fronts though, the wheels bolt directly to the rotor, so if you drill the front rotors with the same pattern as the GSL-SE ones, you can mount those tires.

For those of us with 84-85 non -SE cars, you can just buy the -SE rotors and slap them on the front. The problem has always been the rear.

For those with 79-83 FBs, the spindles in front aren't the same size, so getting custom drilled rotors would be a good idea for you guys. Then you'd only have to worry about the rear.

Either way, you're probably looking at a rear axel swap to say the least.... Probably easier to swap the entire GSL-SE rear end.

In *my* case, I have to swap the entire rear end anyway, 'cause I have drums

Jon

LongDuck

SE rear rotors are very easy to install. They are held on with a single Phillips head screw that is about 1cm in length and coarse thread which requires a handheld impact driver to install and remove. This screw is only used to keep the rotor straight on the rear axle hub when you're installing the wheels. You don't even have to put the screw back in, since the rotor is sandwiched between the wheel and the axle - it's not going anywhere.

I doubt that 12a cars (GSL's) would be any different - if you've got drum rears, you'd likely need a whole rear axle swap. Remember that brake rotors have to be resurfaced regularly and replaced occasionally, so Mazda has designed this system to be easy to maintain. It's not like you'd have to pull an axle to change a rotor...

jfachner72

Well it looks like the amazin' idea has gone down the toilet.....

Yes we can have the rotors custom drilled "BUT" and a very big but the rear axles are drilled as well....

Any ideas on how to overcome this problem??????

Jay
1984 FB

dj55b

iTrader: (2)

sorry to have broken the news to you ... but better now then later when you go to install them on and be like **** ... that doesn't fit on my car. Doing a swap of the rear end isn't that cheap if you don't have the tools and the guts to do it ... and taking the car to a shop to redrill and tap your back axle isn't cheap neither ... I've thought about the idea before .. but no cheap way of doing it.

Arockrx7

Well anyone interested in doing it. I am selling a front set of slotted rotors. fairly new, no runout for $60.00

there is a thread in the 1st gen parts forsale section. im just too lazy to post the link.

evil_motors

iTrader: (3)

okay what holds the rear rotor on the car... or is it a free floater? if it bolts on then we could still do this.. if not i am sure there could be a way.. like getting the axles tapped with the right thread and pattern

Arockrx7

the rear rotor is helod on by a screw that isnt needed. the screw just hold the rotor on when the wheel is off.

evil_motors

iTrader: (3)

okay so you would have to get the rear axles re drilled hmmm that makes it alot tougher.. but its still doable.

boiler81

Why can't the custom rotor supplier (OC?) provide a custom "drill guide" which would use the existing 4 x 110mm lug bolt holes for attachment/alignment of the drill guide. The drill guide would in turn provide a 4x114.3 pattern hole guide, clocked 45 degrees off the original bolt holes. This low cost drill guide could be easily made on an NC machine, and could likely be made for under $75 in small quantities.
After drilling and tapping, the axle hub would then accommodate either 4x110 or 4x114.3 rotors. The drill guide would allow the hub to be hand drilled with the necessary precision, and then you'd need to tap the new bolt holes.
This should be within the skill level and budget of the backyard RX-7 mechanic.

Who's going to contact the rotor supplier and ask?

The drill guide and tap could then be sold to the next RX-7 club member

evil_motors

iTrader: (3)

sounds like a plan..lets get this thing in motion..

evil_motors

iTrader: (3)

actually dont you think we could just switch out for gsl-se axles? or is there a difference in the housings

perfect_circle

i didnt read that mega long post(ADD) so i may be copying him.. but could you use the rotor as an adapter, just have him drill the 4x114.3 studs, and a seperate set of hole in 4x110 and then just shorten our studs, and bolt on the brakes, and then the wheels...just like spacers, or adapers, only without the additional space

evil_motors

iTrader: (3)

that could work but the nuts bolting the brakes down would get in the way of the wheels sitting flush i would think.

perfect_circle

thats why you could shorten the studs, and im sure there is some special lug they use for spacers or adapters, cause i would think they would run in to the same problem.

evil_motors

iTrader: (3)

well when i used spacers they were just a spacer.. you used longer studs and it bolted up the same way.. so i am not sure how this would work.

perfect_circle

http://cgi.ebay.com/ebaymotors/WHEEL...28945082QQrdZ1

this is how it would be done with mini lugs

evil_motors

iTrader: (3)

yeah i could see how that would work.. so .. we can get the spacers for the rear.. and use the rotors that the guy is selling for the front. that could work.. now who is gonna make spacers .. i think 1" should do it. that would leave enough room for the short lug nuts.

GET ON IT MACHINE SHOP PEOPLE

jfachner72

Not to sound dumb........ Isnt the new "ROTOR" a drill guide????
When you put it on the axle it is a snug fit, right?
So why couldnt you just ues that??????

The only problem i see is that you could end up a hair off on one lug or so but i think there is enough play in the bolt holes and also our wheels are "HubCentric"
not "StudCentric" so as long as they are tight they should be true?????

Are the studs actually studs (threaded) or could you use studs (flat head from rear) ?????

Lets make this work guys there are enough of us that if each of us used "1" brain cell we should be able to think of an answer...........

Jay
1984 FB

boiler81

Potentially the new 4 x 114.3mm pattern rotor could be used to locate the new lug bolt hole locations in the axle hub. However, a true drill guide will not only locate the hole with greater precision (if needed?), it will guide the drill normal (aka perpendicular) to the hub. (However, if existing lug bolts only hold down, and do not provide wheel concentricity (centering) alignment, then you could probably stand to have the bolt holes off angle a few degrees.)

I'm not thrilled with spacer/adapters because they typ. add 19+ mm of offset. Do wheel offerings support the extra offset, or are you limiting your wheel choices again?

What's the proper offset (stock suspension and fenders w/o rubbing) for 15 x 7 rims w/ 205-50 15 tires?

perfect_circle

im NOT talking about actually using spacers, im saying drill an extra set of holes in the rotor, (one set=4x110, and the other set =4x114.3) and on the 4x114.3 hole set, just have a part of the rotor recessed for a nut.

are you feeling me? we wouldnt need to make it any thicker, so it wouldnt effect the offset.

do you see any problems this way? if you do, or dont understand let me know, and i will try and come up with a diagram of some sort..