Another rear brake adaptor!!!

[Guest 70240z]

Hi all I just thought I'd Show you something We added to StrictlyZ.com

 

These are CNC'd 6061 Alluminum brackets allow for the bolt up of 79-81 280ZX Brake Calipers and Rotor's on the 70-78 ZCars. The benifit of these is they allow you to use Existing E-Brake location versus other Brake Upgrades.

 

They Run $175

 

//I stand corrected they use 79-81 not 79-83 Brake Calipers and Rotors.

[Guest Anonymous]

Sweet!!!

[Dan Baldwin]

Man, I dunno about this. This part wants to be STEEL. Even the mildest steel is stronger than 6061-T6, and would have much greater fatigue strength and life. I believe some of the HybridZers have made a bracket out of 4340 steel, which I would feel a LOT better about. I managed to get the Maxima bracket for my Z. No worries!

 

Dan Baldwin

B.S., M.S. Aerospace Engineering (structures emphasis)

[Guest Anonymous]

im waiting for Ross for his CNC bracket, allows 240sx rotors and calipers, 11" or so not too shabby

[260DET]

The chart I have from an aluminium supply house gives the following ultimate tensile MPA figures.

 

mild steel : 200 - 300

6061 T6 : 310

2011 T4 : 310

7075 T651 : 570

[johnc]

Aluminum is fine. AP, Brembo, Alcon, et. al. only sell aluminum brackets to mount their calipers. A 3,100lb, 800hp, 14" wide racing slick shod Viper I know used brackets similar to what's picured above to pull 3G stops for 24 hours straight at Daytona last year.

[Guest scca]

ummmmmmmmmm

 

79-83 calipers are NOT all the same so your bracket cannot possibly work with all the years..

 

nice loooking brackets but the price does seem a bit steep considereing its just a maxima bracket copy. - you should have made it with only 3 bolt holes as the one Ross and I did for the 240sx caliper as you dont have to remove the stub axle to mount them then.

[DavyZ]

Mike,

 

Are they available soon?

 

Davy

[biohzrd]

aaawwwwww if aluminium is strong enough for a piston or rod the i think it should hold well enough for this. i've seen it used for things that you would have never believed it would have been strong enough for ( boing 747 , triton missles , engine heads ect...). i look at it like this. it saves you a lot of weight. always a bonus. the price does seem a bit high for something that takes about 10 to 15 minuites to produce on a cnc machine

[Modern Motorsports Ltd]

"the price does seem a bit high for something that takes about 10 to 15 minuites to produce on a cnc machine"

 

Actually it would be a lot more involved than letting a machine run for 10-15 minutes. That piece has at least two setups (ie. manual operations) after the aluminum has been sliced and you can visualize how much of the material is removed so material cost isn't cheap either.

 

Having said that, AFAIK (Mike?) isn't the ebrake geometry quite poor with that setup? Tight turn on the cable? Anyhow, my website lists out pros/cons of 280ZX vs. 240SX setup for Z enthusiasts to decide for themselves (rotor size etc)

 

Mike had a pair of OEM Maxima brackets which we could've knocked off easily enough if we wanted to (all design was obviously done as it exists) so one must figure/hope we were justified in ponying up our efforts to plan/design/prototype/market/finance/complete such a project.

 

260DET quotes tensile strengths whereas Dan's noted a potential fatique variation.

 

John, I agree aluminum can be great if designed (& tested) properly of which we KNOW AP/BREMBO etc have done to great extent.

 

Given an iron bracket is ~ 1lb or less (likely less, just being conservative) I didn't think anyone wanted to absorb the cost of design/production for an aluminum bracket for the few ounces.

 

I'm blabbering now......brackets are IN PRODUCTION this week and next (yes, a good weeks worth of machining). Orders will be shipping out in the order they were received.

 

I don't like 'altering' thread lines but a lot of q's/info popped up above which seemed to have it already diversified.

 

PS 'IWISHIWASATURBO', yes they are 11-3/8's rotors vs. ~10" or so for the 280ZX setup. The 280ZX caliper core costs are high and good 'as is' junkyard stock is hard to find, something I haven't put up in my web. Reminds me, we have a limited number of good used 240SX calipers available with recent orders.

[Dan Baldwin]

I maintain this design should be analyzed. If someone can show me the analysis done to prove it, I'd be glad to review it.

 

As far as AP and Brembo making aluminum brackets, that does nothing to validate THIS particular bracket design. It's not a question of whether aluminum is an appropriate material for caliper brackets in general.

 

Regarding the properties of 6061-T6 vs. 1023 cold finished steel, Bruhn's Analysis and Design of Flight Vehicle Structures (OLD aero bible) has:

 

6061-T6: 42 ksi Ftu, 35 ksi Fcy

1023: 55 ksi Ftu, 36 ksi Fcy

 

MatWeb gives 45 and 40 for the Al, 62 and 52 for the 1023 steel.

 

Not that you'd use 1023, you'd likely use 4140 or 4340.

 

What these numbers DON'T tell you, however, is that the aluminum has no fatigue limit (stress below which cracks will never develop). This *might* not be much of an issue, since there is little to no reversal, and it seems the lifetime number of cycles should be relatively low. Still, aluminum CRACKS.

 

Also, Al properties drop off far more precipitously with temperature. Comparing 6061-T6 with 90ksi 4000-series steel (usig Bruhn), 6061-T6 only has about 59% of its room-temp strength at 450F, while steel has 80% of its RT strength at 500F.

 

Yes, aluminum is a great material for building lightweight structures. That's why the AEROSPACE ENGINEERS (the smartest and best-looking folks on the planet) at Boeing (not BOING!), Lockheed Martin, etc. use it extensively in the design of aircraft and spacecraft.

 

This does NOT mean that a suspension or brake part on a Z can be reliably and safely made from aluminum when the original Nissan part (designed by smart and diligent AUTOMOTIVE ENGINEERS) was steel! Maybe it can be, but some good ENGINEERING design and analysis must be done to ensure safety and reliability.

 

I maintain that I wouldn't put it on my car until I'd done some analysis. There's not a lot of space in that tight radius for adding material, which you generally need to do when going from a steel to an aluminum design.

 

Dan Baldwin

M.S., B.S. Aerospace Engineering

[jeromio]

I'll add my flava to this thread:

 

Bracket cost - I made my own brackets from steel - pain in the ass. I'm poor, but looking back on my ordeal, $175 might've been worthwhile. Definately $150 would be easier to choke up. As to the "15-20 minutes" comment, well, let's just remember that CNC machines are not free (at my old job I had a tiny mini-CNC that might've been big enough for this job and it cost the company $25K), nor is the skill and training that is required to use one.

 

Bracket design - looks very nice. I agree it would be key to make it attach with 3 bolts for assembly ease. That aluminum looks mighty nice. I certainly don't see a problem with using Al and there were some vendors who produced a very similar piece in the past.

 

280ZX calipers - these are somewhat expensive - moreso than I would've thought. As Terry has pointed out (and I confirmed), the doubled piston is a weak point. Tends to freeze up making used calipers useless as far as ebrake auto-adjustment goes. Also, as Ross points out, the cable does have to be convoluted to hook up. It's solvable, but less than ideal. Better than a separate spot caliper (IMO), but if the calipers could go more towards the backside (top I suppose), the cable could be relieved of some stress.

 

At any rate, I recommend getting some junk calipers from a yard, but only to use as a core. I tried rebuilding and basically wasted time and money. But, most places I've checked have a HUGE core deposit. Get either NA or Turbo 82 rear calipers. But be sneaky and use them as cores for the Turbo units - according to Terry these have a slightly larger piston. They look identical though, so, I seriously doubt anyone will notice. AdvancedAuto had the best price (about $80+core), But I keep getting leaky calipers from them.

 

Remember to put the "L" caliper on the passenger side and the "R" on the drivers. I welded washers near the midpoint of the each axle on the front bulkhead, pretty much in the center, to hook the ebrake cable retaining springs too. I moved these springs over about a foot further up the length of the cable as well. Keeps them from interfering. I also created some spacers by cutting slots in some 1/2 inch washers to space the cable end mechanism on the mounting arm of the caliper. The caliper seems to require more pull than the drum did to actuate the brake, so you have to "tune" the cable with washer spacers to get the operation in the sweet spot. I believe this is why proper functioning of that double cylinder auto-adjustment mechanism is so critical. Oh, I also cut out 2-3 coils of the spring on the end of the cable to gain some more pull.

[DavyZ]

quote:

---

Originally posted by jeromio:

I'll add my flava to this thread:

 

...Remember to put the "L" caliper on the passenger side and the "R" on the drivers.

---

 

 

Jeromio, isn't the left side of the car the driver's side, and the right side is the passenger side? Do they need to be reversed in this procedure? Just asking to clarify this for me. Thanks.

 

Davy

[Modern Motorsports Ltd]

Davy, some setups you do swap the intended sides like that. It's a bulletproof step to get them right though, either your ebrake arm is very close or interefering with your strut tube...or (with our setup anyhow) it's at 2 o'clock or 10 o'clock, side depending and happily headed for your ebrake cable with fine clearance to UJ/CV shafts/swaybar/strut tube etc. Our brackets are NOT symmetrical from side to side for those specific purposes, making them asymetrical resulted in the optimum clearances and ebrake geometry. It bumped costs but we figured for all this work we'd better get it right and make it easy for the end user.

[jeromio]

You can't put the ZX calipers on the Maxima brackets on the back side because the strut tube is in the way. So the calipers are mounted forward. Therefore the calipers have to be switched side to side so that the bleeder screws point up.

 

I actually forgot about this myself: when I discovered that my passenger side caliper was leaking, I ordered a new passenger side caliper. Doh! Parts counter guy was not too happy having to send it back and order a drivers side - what kind of an idiot could get it wrong, eh?

[Guest Anonymous]

I agree with Dan. This may look nice, but that doesn't mean it's good. Some further analysis should be done, other than assuming it works because it's a simple CNC copy of a Steel Maxima bracket. It's not an exact copy though, as the material around the bolt holes, although nicely shaped is far less than the stock Maxima bracket. And, as it was already pointed out, it can't work for all the 280ZX rear calipers, as there are two distinct designs, and they are NOT the same as to be interchangeable.

 

Lately it seems like so many people just go out and copy things today, without any engineering thought trying to make a quick buck or two. Granted being an Engineer, this bothers me more than some other people (it's the geek in me I guess), but misinformation leads to a lot of problems. Usually this stems from the fact that someone saw an aluminum part in a catalog and it said "aircraft grade" so they assume that it must be good for their application.

 

Magazines go around quoting "aircraft grade aluminum" to try and fool the masses into thinking that somehow this alloy is the best thing for every application. On the contrary, a good designer will know which alloy should be used with which design. An alloy with high shear strength for shear situations, high hardness for wear applications, etc....Besides, 6061-T6 alloy is way too overexaggerated for what it is. In fact, I'd go so far as to say that 7075 might be a better choice in this particular case.

 

That said, Aluminum may not be the best choice here. The Maxima bracket was steel for a reason. We can only speculate for that reason, but one thing is for sure, someone was PAID to design that part and spec'd steel. The amount of torque encountered during braking can be significant, especially with a sudden and hard stop, which is why I speculate the steel bracket was originally spec'd by Nissan. Aluminum may begin to yield ever so slightly under these conditions which may lead to bigger problems. Cost, on the other hand, wasn't so much of a factor, especially in high-volume.

[pparaska]

Just saw this thread. Another MS Mechanical engineer with structures background here.

 

That bend is very tight and thin. There's alot of bending and shear going on in that area. For all the reasons Dave and Dan mentioned (property degradation with heat, brittleness of 6061, NO FATIGUE LIMIT OF ALUMINUM) I'd agree that steel is the only way I'd go on this design.

 

On the other hand the Arizona Z car rear brakes I have on my car have an AL bracket. But it's a flat plate type of bracket, no bends. This makes a HUGE difference as there are no nasty out of plane bending and shear going on in a tight corner (stress concentration).