Integral Caliper

[rjwoods77]

I was looking though some old pics and saw a car with a upright with integral caliper machined into it. Besides the obvious equipment failure side of things do any of you know why this isnt a good idea?

[rjwoods77]

I was looking though some old pics and saw a car with a upright with integral caliper machined into it. Besides the obvious equipment failure side of things do any of you know why this isnt a good idea?

[adrial]

Well, it'd be expensive (or time consuming) to make from a machining standpoint. You'd have to start from a pretty huge block of aluminum and if you screw up somewhere along the way you now screwed up the upright AND caliper as opposed to one or the ohter.

You have no means of insulating the upright from the caliper heat if you deam it necesary.

It seems like a lot of time/effort/money to save the weight of 2 bolts, maybe 4 if you include a bolt on caliper mount.

[Denny Trimble]

Not to mention, you're locked into using the same material for your uprights as your calipers (aluminum). Uprights are all about high stiffness and low weight in a confined volume, and it's hard to beat boxed steel in my opinion.

[GSpeedR]

An all aluminmum caliper/upright means rapid heat transfer straight to your wheel bearing, which is going to be a little upset about that.

[Jersey Tom]

Mucho machining time. No modularity. Heat transfer issues (as has been mentioned).

[syoung]

Our second ever entry (a number of years ago) featured exactly this - an all-in-one, in-house aluminium upright/caliper. From what I've heard, the design judges weren't too impressed, especially as there was little eventual weight/stiffness gain. Their main criticism was that the team had spent a lot of time and effort on was such a safety-critical part which is readily commercially available in almost every imaginable size.

I believe sealing can often be a problem in student-designed calipers, over and above all of the problems previously mentioned.

If the rest of the car is already perfect and you're confident designing the only part of the car which slows you down when things go wrong, then fair enough, but until then...

[Colin]

we ran this type of setup in 2003, and our reason for doing so was mainly clearance. We had a very small scrub radius (6mm) and we couldn't get an off the shelf caliper to clear the rim. We didn't have any heat related issues but we did have problems with piston retraction due to our lack of knowledge of seal groove geometry. As for the judges, we came second in design that year only a couple of points off WA so they obviously didn't hate the concept. We went back to a more conventional setup in 2004 and achieved a much better pedal feel and braking performance, but this was due to brake design and not rely related to having the brake/upright combination.

[rjwoods77]

HEy Colin,

What exactly do you mean by better brake feel?
What was wrong with your first setup. As far as retraction, as long as you use a tapered seal groove with a square seal then it should have a problem. Did you do this?

As far as everything else, the only reason I would do this is if I did a billet upright. I just figured based on cnc'ing it that it would cut down on overall time to machine both items. Since I am using 6 inch brake rotors my choices for calipers vs. how big they are is limited. I was already planning on making my own calipers so.... As far as heat transfer is concerned I dont see how making it integral would really make it worse. Your just increasing the amount of material to dissapate that heat. I could see getting the bearing too hot but with the way I am doing my brakes(between the a-arms) I should have sufficient air flow to help cool. Dunno. Just throwing some ideas around. On the manufacturing side I might be taking a shot a laser metal dep. so it would make even more sense to do it this way. I agree with you completely on steel Denny and I would do a steel depostion which would also make the caliper steel which should make it pretty rigid overall as a unit. Again, just throwing some ideas around.

[Floridagator]

If you have any problems with a weak wheel bearing or spindle, the effects of piston knockback from the disc deflection will be most severe if your caliper is at the bottom of the knuckle--which is where I've seen the other examples of these designs.

I also agree with previously mentioned comments--why reinvent the wheel, or caliper in this case, when there are so many good and readily available options on the market?

[Colin]

Rob
"better brake feel" is a very open comment, i guess what i meant was, in my opinion, we got a more progressive feedback to the driver on the 2004 system and I think that our piston seal groove had a lot to do with it because we didn't have a tapered seal groove, as you mentioned.

[ben]

One of our old cars had this setup. Admittedly I'm useless behind the wheel, but I could never tell any difference in terms of braking performance and it was heavier than a well designed fabricated steel upright with a separate caliper - and probably less stiff as well.

In my opinion it fell into the category of innovation for the sake of innovation, i.e. gimmickry.

Ben

[adrial]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rob Woods:
I agree with you completely on steel Denny and I would do a steel depostion which would also make the caliper steel which should make it pretty rigid overall as a unit. </div></BLOCKQUOTE>

Maybe I'm the only one...but what is a steel deposition? I searched google and I kind of got a slight idea, but would appreciate an explanation.

thanks,
Adrial

[rjwoods77]

powder metal deposition. A laser fuses metal powder into shapes. Very star trek. Basically saves on material costs because you arent cutting from a billet. Also there are savings since the powder isnt made into billets so the material costs are down form not making net shapes. Laser is expensive but the costs are going down. Basically allows you to have total design freedom. Can als switch metal types during manufacture as well. Pretty neat process. Just gotta see what the total cost is involved.

[adrial]

Thats the idea I got from google...pretty amazing stuff.

Do you have any information on companies/people that do this?

[Z]

Rob,

FYI. The Citroen Cx, first sold around 1975, has one piece aluminium front caliper/uprights. The rear mounted caliper has 4 pistons (2 inside, 2 outside), with a separate pad and clamp for the handbrake, so it makes up most of the casting (or forging?). Growing out of the caliper are three lugs for the three BJ's and a flange for the bolt-on bearing/axle unit.

I have a Cx as my current daily driver. I have never heard of any problems with the front brakes/uprights. The Cx is not a sporty car but Citroen traditionally used to overdesign their brake systems. The brakes operate from the central hydraulic system so they are always "rock hard" (the brake pedal opens a hydraulic valve that feeds oil at ~170 bar/2500psi from a central accumulator to the calipers).

For larger uprights I would favour hollow steel (ie. fabricated or deposited), but for your 10" wheels and 6" disc a compact machined unit, maybe even steel, might be light and stiff enough.

Z

[CMURacing - Prometheus]

http://www.prometal.com

they do a kind of hybrid powder metal deposition, its more like powder metal casting, but you still get good stuff. and they can do mixed material alloys: their specialty is 304 stainless with bronze, allowing good fatigue and crack propogation properties with the strength of the stainless.

[rjwoods77]

Z,

Citroen has/still makes some interesting cars even thought they are ass ugly. Like the DS with its inboard rotors and centerpoint steering. My ball joint center to centers are 8". With the laser dep. process I can pretty much do what I want and I ran some numbers and the overall time to fabricate and hours or manufacturing time would be cheaper doint this way, if..., and its a big if, if the laser dep process is comparable to other machine processes in bucks/hour. I could do it out of sheetmetal but at typical welding rates I could make that up in reinvestment into machine costs. In the end it looks like it will all equal out for formula costing rules(again if the labor rate on the machine isnt too bad which I am farming around at this point). My general question was if there would be a problem doing it as one piece and from all the responses I have gotten so far it looks like it isnt a problem. The only problems people seem to have had were ones they brought on themselves. I am actually soely designing a new caliper of a company that I am working for right now. Its on the lower tech side of things due to the market they work in but a challenge none the same. So I dont think I will have a problem getting the caliper right. I actually thing it will be more rigid than the normal style of doing it. But thats just my opinion.

If anyone knows where I can get a caliper that fits a 6" O.D. and 4 " I.D. and .280" thick AL-MMC rotor that isnt some bloated MCP caliper then let me know. I looked but cant really find anything that I didnt think I could do way better on. Thanks again for input everyone.

[rjwoods77]

Almost forgot, any reason not to use a steel caliper since my caliper is going to be small as hell anyway.

[Matt Gignac]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rob Woods:

If anyone knows where I can get a caliper that fits a 6" O.D. and 4 " I.D. and .280" thick AL-MMC rotor that isnt some bloated MCP caliper then let me know. I looked but cant really find anything that I didnt think I could do way better on. Thanks again for input everyone. </div></BLOCKQUOTE>

Where did you guys source the aluminum MMC. We've been running Al-MMC rotors for the past four years, but we're running out of the castings we had made back then, and the company we had dealt with stopped making the stuff. We found a few places, but they were charging ridiculous amounts and weren't interested in any kind of price break or sponsorship.

Matt Gignac
McGill Racing Team

[rjwoods77]

Still working on my sourcing. When it works out I will let you know.

[Z]

Rob,

Only disadvantage of a one piece caliper/upright that I can think of is speed of disc change. Depending on the design you may have to split the caliper to change the disc, then bleed the system, clean up the mess, etc... If you mount your inboard-of-upright disc on a flange using bolts rather than studs, then this shouldn't be a problem.

Disadvantages of steel calipers? After about 10-20 years, if you don't regularly change the brake fluid, then you will get a rusted bore and leaking seals. Ie. not a problem. http://fsae.com/groupee_common/emoticons/icon_wink.gif Absolutely no problem if you use stainless steel. SS has a thermal expansion coefficient half way between steel and aluminium, least thermal conductivity of most metals, and better strength/fatigue properties than it is usually given credit for.

Z

[Dominic Venieri]

Our team began using integrated upright/calipers in 1999 (for the 2000 comp) in the front, and continued that through the 2004 comp year car. For 2005 this was changed to a bolt on caliper design.

Pros - tight packaging, less hardware, possibly lighter weight, and in our case, lower CoG by positioning the caliper at 6:00.

Cons - difficult to machine, less interchangeability of parts, expensive, expensive, and oh yeah, expensive.

[DY]

There was a team at 2005 who did their front uprights with titanium deposition, wasn't there?<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rob Woods:
powder metal deposition. A laser fuses metal powder into shapes. Very star trek. Basically saves on material costs because you arent cutting from a billet. Also there are savings since the powder isnt made into billets so the material costs are down form not making net shapes. Laser is expensive but the costs are going down. Basically allows you to have total design freedom. Can als switch metal types during manufacture as well. Pretty neat process. Just gotta see what the total cost is involved. </div></BLOCKQUOTE>

[CMURacing - Prometheus]

yes. and they were pretty cool.

[adrial]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by CMURacing - Prometheus:
yes. and they were pretty cool. </div></BLOCKQUOTE>

I assume that was Carnegie Mellon? May I inquire about the cost/who performed the service for you?

thanks,
Adrial

[Jarrod]

SAE paper #2004-01-3546
Design and Manufacture of Titanium Formula
SAE Uprights using Laser-Powder-Deposition
Graham Erickson, Matt Heath, Bryan Woods,
Daniel Dolan, Eric Henderson and James Sears
South Dakota School of Mines and Technology

[James Waltman]

Yeah, it was SDSM&T
http://dot.etec.wwu.edu/fsae/HostedPics/2005_Detroit_7/images/IMG_0308.jpg