Drill TurboII rotors to 4x114.3?
 

Hello, I was going to do the 5 lug swap but I have decided I don't want to buy new rims for my car. Would it be possible to just take my TII rotors and drill them out to 4x114.3?

I am thinking I only want to upgrade the front to the larger rotors and calipers and I will just leave the stock rear 4 lugs...

Any clearance problems with the phone dial 14in rims?

I am assuming I could just take these to a machine shop and have them do it.. I saw them do something like this in SCC with a Honda and it got me thinking.

THANKS!!

Quit Thinking! LOL
Any thing is possible, just make sure they mill the holes "hub-centric"

Cool so I can do it.. Does anyone know if the 4 piston calipers will fit with my 14in phone dial rims?

what FC's come w/ 4 lug thought they were all 5

S4 SE/base models I think

No, I seriously doubt 10.9" rotors plus 4 piston calipers will fit under a 14" wheel.

Hmm guess I am gonna have to pull the tire off when I get home and do some measurements..

Even if I have to upgrade the rims there are 4 lug universals all over the place for Hondas for way cheap...

Still, that's a pretty ghetto way to do this..

If it were me, I'd look around for a set of GXL wheels for sale around here, and put those on, if you haven't already bought a good set of 4 lug wheels.. Hell, the pick n pulls around here easily have a full set of GXL rims, for cheap.

PaulC

I agree with silkworm... hell, the person who is selling the turbo calipers might be selling their wheels too? (wheels aren't much good without brakes...)

I have the entire conversion kit but I don't really want to even bother. The fronts are easy but the backs look to be a pain in the ass.

I only really care about getting the big breaks in front so I was thinking it might be an easy fix just to drill out the new rotors and slap them on with the calipers using the rims I have right now. If it won't fit then I won't do it.. It IS easier to find light weight universal 4 lugs thou..

meh... lets put it this way.... the 4 bolt hubs were designed to be used with SMALL calipers... the force generated by big brakes will be greater and could lead to premature failure. as a result you may end up swapping the 5 bolts in later, and then you won't have any front rotors 'cause they have too many fuckin holes in them to be useful....

First off drilled rotors are not the way to go. Slotted is the way to go. Drilled rotors will crack between the holes. How bad these cracks are is dependant on many factors. Also you are just removing surface area. I don't think drilling used rotors not ever engineered to be drilled is a very good idea. Ever seen a brake rotor shatter? I guarantee you don't want it happening to you.

As far as the rotors and 4 piston calipers fitting into 14'' wheels i doubt it seriously. How are you going to mount the calipers without the proper 5 lug hubs?

If i were you and you are just looking for more stopping power, get braided steel lines, flush and fill the brake system with good new brake fluid, and get some hawk brake pads. This will improve your brakes so much you will be amazed.

If you have the 5 lug parts just do it right and be done with it.

Jeff,

He's not talking about crossdrilling rotors, he's talking about drilling new lug holes in a set of 5 lug rotors to convert them to 4 lug.

Re: Slotted Rotors being the way to go to avoid cracks, I provide this as evidence to the contrary. These were a set of powerslot rotors off of my Trans Am after a weekend running Carbotech Panther pads at Thunderhill raceway.

http://www.lcaf.com/silk/psrotor-1.jpg

Regards,

PaulC

DUhhhhh, my bad.

I am not saying that other rotors won't crack, just that drilled rotors seem to do it more often.

That is a nasty crack. Did you try to return them? Have you used drilled rotors in the same conditions with no cracking?

Return them? Heck no, not after two days racing on them.. Same thing after I pranged the Trans Am at Sears Point.. I chose to go racing, I get to pay for my mistakes..

Oh no, I'm not saying drilled rotors are better, in fact I've seen plenty of pics of dead x-drilled rotors too. I race the RX-7 with plain stock Mazda rotors, nothing fancy, and I used to track the Trans Am with stock rotors, after the experiements with slotted rotors failed spectacularly. Modern pads don't produce the gases that the pads in the 60s and 70s did, it's really not necessary to run slotted/x-drilled rotors.

PaulC

Could 4 POT, Calipers be ghetto fitted onto the rear of a T2 ? or GXL ?

ok, theres no way the TII calipers (if they were fab'd to fit a 4 bolt hub) will stress the hub or other 4 lug brake components to the point of highly increased wear and premature failure...the car will simply stop harder. I also think the time and energy in 'making' them fit is comlpetely not worth it. The best bet is to either complete the swap with the peace of mind of proper fitment and clearances or simply upgrade some of your stock stuff...stainless lines are cheap and effective as well as a nice street comp pad like Hawk offers. Provided your rotors are healthy this is a great low cost street upgrade. Cross drilled vs. slotted is just about preference..what looks best with your wheels and tires. Sure, both can be effective from an engineering standpoint, but much much less so in a stock rotor size on a street car. I think the stock systems for all 2nd gens are plenty for the street provided you have a nice sticky set of tires.

Tri - what's the point? 75-80% of your braking force is generated by your front brakes.

PaulC

Hi Guys,

I have a '86 Base model (picked it for its lighter weight and simple steering setup), and it has 5 lug brakes on the 4 lug hubs.
I did the swap.

Here are some facts to consider.

The part in the front suspension where the calipers attach to, is the same part number for 4 lug and 5 lugs setups. Both types of calipers have identical attaching points. The difference between them, apart from the obvious piston count, is that the 4 pot caliper sits a bit further away from the hub to accommodate the increased diameter of the disc, which by the way is about 1/2 an inch bigger in diameter and somewhat thicker than the 4 lug version. They are not much bigger but they do a better job at dissipating heat, and avoid fade.

The 4 pot calipers use hard lines instead of flexible lines and they should be used. Not only do they not flex and swell under pressure like flexible lines, it is nearly impossible to get flexible lines that bolt to the hole that the calipers have.

The Brake master cylinder is the same for both models, but the brake proportioning valve and brake booster are not. If only the calipers and discs are replaced, you will need to apply significantly more pressure to the pedal to get comparable braking. There is more surface area in the four small pistons than the single one in base calipers, but basically the same amount of fluid is displaced when braking, in both systems. That is why the bigger booster is needed. You can live with a small one but it is not fun. The proper brake proportioning valve is needed for two reasons: proper brake force balance between front and rear axles, and to obtain maximum benefits of increased braking ability.

About the big calipers fitting in a 14" inch wheel, I can't say they do, since I have 16 " 5zigen staggered wheels on mine (the reason why I didn't want to loose the 4 lug hubs) but I heard they fit with VERY LIMITED clearance. It is so little that self adhesive wheel balancing weights won't fit in the gap. Even a mildly bent wheel will rub the caliper. It is not safe.
Plus the big brakes generate more braking power and unless you have ultra gripy tires, what you can fit in a 14 inch wheel is not going to live up to the newfound braking ability. Result: Frequent wheel lock up under aggressive braking (embarrassing in public and not a good thing for performance).

Finally, I did only the front brakes, drove a few days and then went running back to the pick-a-part for the rear brakes and the rest of the mentioned stuff from the donor car, which ironically had rear-ended something.

It was worth the effort though. If you don't mind all that is involved, I say go for it. Otherwise, just upgrade to performance brake pads ( I use Hawk HPS) and SS braided hoses. You will definitely feel a difference.

Sorry for the long reply. I got a bit carried away.

Cheers

Kenneth

^ dude, this thread is from 2002.

Wouldn't they all have the wrong offset?

The braided lines for the single piston calipers will bolt right up the 4-piston calipers and eliminate the hard lines too.

Actually, that's semi-wrong.
Keeping your smaller MC (some 4-pot caliper cars come with a larger 15/16" MC but not all) and booster will require more pedal travel, not more pressure.
The brakes might feel weird since you're pushing further but the effort isn't really different.
Can't say I noticed any difference at all between prop valves and I've not only tried both but also units from completely different cars (currently running 929 booster/MC/prop valve, previously had Infinity set up on).
Competition braking might expose some differences but not normal street work.


If you are "frequently" locking up your tires from aggressive braking on the street, you're doing it terribly wrong.
Having had both, I'd go so far as to say the only advantage the 4-piston calipers have on the street is a higher bling factor- the single piston units work fine.

I used the hard lines because no one can argue that a flex line no matter what, expands under pressure where a hard line does not. Also, I said nearly impossible, not absolutely. I found that the flex line leaked a bit at the thread. But that's no biggie.

The brake pedal transmits the pressure applied by the driver to the pads by hydraulic means. It is a matter of simple math, if anything else. If you apply 15 pounds of pressure to a 1 inch piston area, you'll have a higher pressure per square inch than if you apply that pressure to 2 1 inch pistons. Although it is not 4 times the area, 4 pot calipers have more piston area that needs pushing compared to the big one on single piston calipers. Also, Mazda fitted a bigger booster for a reason and neither you or me can outsmart them.

Proportioning valves will not yield a different feel to the brake pedal or vehicle behavior at low speeds. They do tailor how much braking the front and rear axles are providing. Four piston calipers brake better than single ones (I hope no one else is dumb enough to think they are for "bling only") The proportioning valve limits the amount of braking provided by the rear axle, so that in an emergency stop (something that happens on the street) the rears never lock up and result in oversteer. The proportioning valve for 4 piston calipers takes this into consideration, as well as the other differences in the system. If your fronts are braking to much compared the rear, your fronts will lock up much easier since they are doing most of the job here, and unlike a front wheel drive car where there is significant weight on those tires, RX7's have a near 50/50 weight distributionand not enough weight over the tires to prevent lockup. I've already gone to far explaining what someone with sufficient technical knowledge can understand and deduct. If you can't see past normal street driving under sedate conditions, why buy a sports car?

I drive mine hard when ever I can. I like to go fast and like to know that my car will behave its best at the limit, where ever that is.

To drive passively, get a Prius.

I think you might be confusing pressure with hydraulic advantage.

Of course no one would argue that, it'd be stupid.
The real question is: Given that the flex line will expand "X" amount more than hardline under "Y" amount of pressure, how much extra input will be required after adding 8" more flexline to the circuit?
I'll bet you couldn't tell the difference- under any circumstances.

The fact that you failed to install the softline satisfactorily doesn't make the job "nearly impossible".
I've done it four different times- successfully, so can I claim it's "100% guaranteed"?

That math is so "simple" it completely fails to address the issue.

The germane issue is not the PSI at the pad- both a 15/16" and a 7/8" MC will provide the required pressure- the issue is how much effort over what distance is necessary to achieve the target pressure.

Your effort at the pedal is multiplied in three areas before it hits the pads...the pedal itself, which is a lever, the brake booster and finally, the master cylinder.
Leave everything the same but swap in a smaller MC and the only change is the pedal must travel further to achieve the same result.

Not all cars with the 4-piston calipers came with the larger booster (or the larger master cylinder, for that matter) so Mazda makes it hard to outsmart them by being inconsistent.

Proportioning valves don't "tailor" anything at the front axle, your front calipers could care less about the prop valve...indeed, they have no way of knowing there is one present.

I stand by the assertion that the upgrade is sheer "bling" on a street car.
At this point I must admit that not only have I converted my car to 4-piston calipers but recently also swapped in the vented rear rotor setup- knowing full well it would make no practical difference. After rebuilding all four calipers, I painted them red.
Red.
And I did it unironically...
There are many other major factors that contribute to stopping distance- suspension, brake pad compound, tires and the real wildcard, the road surface itself.
Since the single piston calipers are perfectly capable of locking the wheels, what extra have you (or I, for that matter) gained by upgrading the calipers?

Yup, you went too far all right.
If by "sedate conditions" you mean no tachycardia, then yeah, that's me.
I'm a poser, I admit it.


See?
Knowing you're out there, driving at the limit, pushing the envelope, going fast, makes me glad I upgraded my brakes.

The problem with this is a little something called wheel fitment. Yes, you "can" get wheels from a Honda civic, or a Chrysler sebring... but they will look like shit, and will be really "sunk in" with crazy high offset, most around 42mm.

Also, the reason for doing what you want to do is stupid, it would make sense to do this if you did not have the swap already, or had a $3000 set of 4 lug wheels.
If being lazy is your reason for doing something the hard way around (redrilling calipers, having brake bias issues, and etc) then you should sell your car right now.

Proper shit for an rx-7 are 5 lug 17x9.5 wheels, with like 25mm of offset at MOST.

Posted for SEARCH purposes...