JPrevost

I know OEM brakes are floaters and racing brakes are fixed but from being in daily drivers with fixed calipers... why bother with floaters? Especially when the price of good Forged Superlite calipers are only $125 a piece and pads are $55 a set. I just want to know some reasons why you went with what you did.
Was it fear of noise, pad taper, pad selection, feel?

edit: Just read https://www.thirdgen.org/techbb2/sho...hreadid=252511
I didn't see that before I posted.
Just another reply to "getting GM parts from any parts store" well if you don't mind spending the extra $$ on 1LE rotors, C5 rotors are only $26 a pop at Napa. I'm going to get 3 pairs for under $160, tell me that isn't a steal of a deal even if they are cheap quality... can you say mechanical advantage = less heat = less likely to warp .

Dewey316

you have to be much more presise when setting up the fixed calipers there is some room for the mounting being a little off with floating calipers, with fixed you need it dead centered.

idealy you would use fixed calipers, and floating rotors. (my next project )

JPrevost

A common misconception is the requirement of floating rotors with fixed calipers. In racing floating rotors are used to compensate for the metal expanding (aluminum hats and iron or steel rotors). Fixed calipers with more than 2 pistons on a side in effect don't need to be "perfect". The biggest problems come from single piston fixed calipers that are off-center. You'll get pad tapper problems. I did a little doodly to explain my point, obviously it isn't to say setting up a fixed caliper should be close it good enough but that it does compensate at the expense of caliper lifespan, not braking ability.

JPrevost

Here is an animation of a 4 piston caliper at 3 degrees which is WAY off. It's hard to be that far off with the eye. The pads (if new) can jam and not release. Binding is an issue but a degree or two does nothing different except decrease your calipers life span by distorting the pistons WHILE being sideloaded from normal brake forces.
Obviously I'm a bit biased but I noticed that all fixed calipers are lower profile than the OEM floating calipers. The older PBR's are pretty thin but they also distort like MAD in comparison to small fixed 4 piston calipers.

ebmiller88

iTrader: (7)

As you know I've been playing with brake setups for a while now and the main reason I've stuck with the GM floating and pin guided styles is the ease of finding replacement parts. You can always buy a pad or guide pin from GM or Auto Zone if you need one, but a Wilood part will take a little time to get in most cases. I don't argue the better quality and performance of say a Wilwood caliper, but for the regular guys, the GM stuff is easier to get and service, IMO.

Ed

89_3rd_gen

http://www.stoptech.com/whitepapers/knockback.htm

JPrevost

Interesting, that would require a LOT of force to move the rotor that much in comparison to the spindle. Usually they'll move together, not to mention you shouldn't be doing hard braking while turning, but still something I hadn't thought about.

Dewey316

knock back isn't applying brakes while turning, it is the pistons being pushed back in while turning, so the piston has to move further once you do apply the brakes.

BUT, do not that a 4 piston fixed caliper engages VERY fast even with knock back considered. if you've driven a car with fixed vs floating calipers, you will undertand, the reaction time between the two is night and day.

vsixtoy

This is something that just requires experience in the car and what it will do-when. Its not dangerous if you are familiar with having knockback on one corner, but not another. This will remain predictable throughout the race course lap after lap.

Cars have been this way for years. Thats why you can never jump into someone elses car and run it as hard as they do right off the bat.

JPrevost

I can see where floating rotors would solve the "kickback" problem. So for regular racing or REALLY stiff feeling pedal, floating rotors are a must.

Dewey316

the nice thing about floating rotors, both pads will engage at exactly the same time, with the same force. you will not end up with one pad contacting the rotor sooner, or putting slight more force on the rotor, because you are just a fraction of an inch off in centering it.

vsixtoy

John, The fixed calipers are the same pressure also on each pad faces. Reason why is the fluid cavities on each side of the caliper are connected on the same hydrolic system. If one side were to ride off of the rotor slightly because of knockback, and then the pad closest makes contact first - there is no build up pressure to squeeze the rotor until the cavity pressure builds from the other side making contact- then equal pressure will result on each side squeezing the rotor.

The time it takes pressure to even out on both side of the caliper fluid cavities is MUCH FASTER than the time it takes the entire heavier and more binding "floating " caliper to center in order to sqeeze the rotor. Its faster to center just the pads than it is to center the entire caliper and pads. Fixed squeese and release smoother and quicker.

The floating caliper actually has a greater chance of uneven pad pressures side-to-side because the floating caliper can hang up on the floating pins.

Dean

3.8TransAM

I wont get into the theoretical reasons, or from an engineering standpoint, but I play with and see setups that definitely work!

The latest R Jaguars come with Brembo 14 inch rotors in the front(crossdrilled) and 4 piston calipers that are of a floating type design. these things will put u threw the windshield with room to spare :-) Parts are assinine $$$ due to the fact it is Brembo stuff(and Jag markup) , but amazing brake setup.

OEM app wise the floating vs. fixed would appear to me that the flaoting, would tend to have less pad clunk or noise when the brakes are applied rather than a possibl;e slightly uneven app with the fixed caliper? Just a thought. But dumb things loom huge when most of your customer base is automotive illiterate and plain clueless.

later
Jeremy

ebmiller88

iTrader: (7)

Oh man how true...


Ed

Dewey316

Brembo is making a 4 piston floating caliper? care to back that up?

JPrevost

They are monoblock calipers but it sounds a lot like a fixed caliper, especially if it's 4 piston. I haven't even heard of a 3 piston floater. Besides, with a lighter vehicle (aluminum) and 14" brakes I can't see a Jag needing large racing calipers for the reasons you said about the buyers .

Triaged

I haven't seen many (any?) aftermarket racing type calipers that have a dust seal on them. They have just the piston o-ring and that is it. This will allow moisture into the system easier as well as a greater chance of dirt. On a race car they are fine because they are inspected so often and the fluid is also changed quite often. I wouldn't have a problem with some wilwood calipers on a weekend toy...but not on something that I was going to just put gas in and drive to work every day.

Justins86bird

Alot of the Wilwood guys end up rebuilding them every year with the dusty roads around here.

JPrevost

And it isn't cheap. A rebuild with new pistons and rings will cost you over $80. That's just for a pair of calipers, more for all 4. That isn't something I mind though. Rebuilding a caliper with the right tools takes very little time, but it is an evening project.
I bet there is a grease you could spray onto the caliper pistons/pad backs to keep the pistons from getting junked up too bad. Something that's thick enough to leave a film but will flow at high heat to protect the pistons and seals. I'll probably find something industrial and try it out.

Justins86bird

Remember, grease is sticky. More then likely attract dirt and hold it in the bore between the bore and piston. The dirt will grind up and mix with the grease and act as an abrasive.

JPrevost

Actually it won't act like an abrasive because it's soft, that's the purpose of grease. What happens is yes, dirt and dust get into the grease but if it's pretty solid the particles stay on the outside where the metal is protected. No grease would result in having pistons coated in dirt retracting into the caliper and chewing up the piston seal.
Even if there was a lot of dirt in the grease there is no pressure pushing the particles onto the pistons like in a ball joint (which have boats ). So I think a good high heat grease should work, maybe just that orange brake squeel stuff, anythings better than nothing. Keep in mind I will be keeping the brakes clean but it will be drive daily so road salt and dirt are a big issue.

Justins86bird

Since the grease will be used in a moving part, it will act as a lubricant. Just because it feels soft doesn’t mean it’s not causing wear. Once the grease gets contaminated by anything, be it dirt or metallic brake dust, it will cause wear in a moving part.

My advice to run them without grease and inspect them regularly. You have to do the same even if you greased them.

ebmiller88

iTrader: (7)

After reading this discussion I'd prefer a caliper with dust boots.


Ed

vsixtoy

If you live in any area that has bad whether (snow conditions, or very muddy roads) I would fully agree with having dustshields on the pistons.

I personally live in sunny So.Cal were the roads are very clean and dry. I have run calipers without dustsheilds on a few other cars of mine for years- the Vette has had them on it since '68 when my father bought the car new and immediately modified it. He use to drive this car to work everyday and have never had a problem with daily use. I had a Karmann Ghia with an aftermarket 4-wheel Wilwood setup that I drove for about 8 years and never a problem. The only problems I have ever had with any brake caliper dustshields or not is from the car sitting for long periods and the seals leaking- this happens to any type of caliper. I don't even run backingplates on any of my performance cars.

JPrevost

What I'm saying isn't new. Racers around here have been putting lithium based grease on there race cars for decades now. Anything without a boot needs to be protected with something, leaving them out to collect grime and then retract into the piston seals is not good karma. Having some kind of grease on there WILL protect the piston seals by creating a barier between the dirt and seal. Two of my good friends race there cars on road tracks twice a year (still going to school) and that's there daily drivers with wilwood calipers. The RSX has dynalites and he's put lithium grease on the pistons every oil change and it's been over a year with no troubles, he's also located in Rochester NY! The other is a Maxima that had Billet Superlite calipers which were used and then he put them on his car, they sucked. The pistons had crap stuck to them and wouldn't push out so he was only using 2 of the 4 pistons. I don't know if he's put lithium gease on the new calipers or not, probably should.

JPrevost

I agree. Too bad dust boot 4 piston fixed calipers aren't cheap.
Oh, and another thing, all of the calipers I've taken apart that had dust boots had grease inside. That might not apply to stainless pistons or exposed pistons but it's just extra protection, obviously.

91Z28-350

Does the Spohn kit have dust boots?

JPrevost

No, they're wilwood calipers, $125 a piece for the complete caliper....

ebmiller88

iTrader: (7)

I was poking around looking for info on Wilwood calipers and it turns out the DO offer a caliper with dust boots. Check it out:

"DynaPro or DP: The new DynaPro caliper from Wilwood is the first to be a fully "booted" caliper for those who have been requesting a caliper of all weather performance and a very compact design. The DP is radial mount only thus requiring proper adapter brackets for use on our Street Sport kits. It has a number of bore size options and should be considered primarily a street caliper. It is fit only to the .81 rotor options. "

Pic is here:

http://www.tceperformanceproducts.com/Calipers.mgi2

OK Dean...what's meant by "radial mount"? That means it needs brackets that bolt to it unlike the Superlites which have cast mounting brackets?

Ed

PS: BTW, .81" will be the same thickness as a C4 Standard 12" rotor... Hmmmm...

vsixtoy

Ed, thats the same basic caliper I have on the back of my car now, only
1) mine isn't booted-I live in great sunny So.Cal
2) mine is not radial mount- it has standard mount tabs forged into the body design with a 5.25" spread on the rear to clear the C5 style drum parking brake.

What radial mounting does for a caliper is allow it to be shimmed radiusly from the center spindle. The shims can be added or taken away to set the caliper to exact tolerances of the rotor.
I'll give an example-

Lets take my setup I'm building for the fronts- the rotor is 12.90 to the outer edge.- you don't want the brake pads to touch or go beyond the outer edge, but you want them basically just kissing the bevel lip at lets say 12.87". without shims you might have it at only 12.75", with maximum shims I can set it past 13.06" so I can run a 13.06 rotor also if I ever wanted to (more options in 12.90 rotors thats why I choose to go down to them)

vsixtoy

The other added benefit to "radial" mount calipers is- you can just undo the two top radial nuts and pop the caliper off in order to pull the rotor. Very easy access. No more having to work behind the rotor to undo caliper mount bracket bolts.

Radial or non-radial "open top" style calipers.
The beauty with Wilwood open top calipers(this goes for any other manufacturer of this style also- we know there are too many to list) is I don't have to pull the caliper off at all to change brake pads. So if I am running at a track and want to quickly change pad compounds, I can do so rapidly.

ebmiller88

iTrader: (7)

Thank you Sir, that helps a lot with my understanding of how they work. I really like them and maybe using them in a future setup on a truck...now to just get this rotor and hat design stuff figured out....


Ed

vsixtoy

Ed, I might also add (even though I'm pretty much sure you have this figured out already- I will state it in general for any to read)

It is alot easier to measure and build your own setup using the radial mount calipers because you have room to fudge them up and down, and side to side with shims. So as long as you are a little conservitive on you custom bracket figures, you have room to shim them out to exact tolerances. rather than trying to measure something in a "fixed" position and getting things just a little off. I'm no professional machinist and rely on fair primitive tools for measuring compared to what they use sometimes. A professional machinist can also afford to "round file" a mistake and start over without great out of pocket cost if the final fitment is not exact. I have to pay full price for a custom order whether its correct or not. So far, I have always been lucky with anything I have had machined- but there will be that day.

Dean

laiky

is there a performance advantage to radial mount calipers? i would swear there is, i know there popular with motorcycles , but i can't remember what exactly they do.

vsixtoy

Slight added cooling, but not that much. The radial mount allows for airflow to surround the caliper better on the mount side.

Matt87GTA

For those looking for booted fixed 4 (or more) piston calipers, I am fairly sure that most of the Brembos off of Porsche's and the like (street cars) have dust boots. I know the 996 calipers and the Mitsu Evo ones have boots as I have seen them in person. And they aren't that much money if you can find them used.... One of my buddy's just found a set of the Evo front 4 pot Brembo calipers with pads on eBay and paid something like $300 shipped!

I really like the idea of going to a radial mount as well.... Swapping rotors is much much easier with a caliper mounting setup like that where access to the hardware is so open....

So what I am wondering right now is.... Will a radial mount Wilwood Superlite - with the mount included - directly replace a standard mounting ear style Superlite? I see you can get the 3.5" spread....

MrDude_1

if by radial mount you're thinking of somthing like buells, brake setup (or the aftermarket copies) thats not what hes refering too.

laiky

no not Buell. Most japanese sport bikes, and some bremo's on ducatis i believe. i know what they look like