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The vented rotors on my Deman Motorsport SR7 are stock early 90's T-Bird and are extremely heavy, having been designed for a car that is almost 4 times the weight of the SR7. They barely get warm after a track session, especially the fronts. Does anyone know of lighter, unvented rotors that would fit and do not break the bank? All the 2 piece ones with aluminium hats that I have seen are ridiculously expensive.

It is unlikely to be a 90s tbird due to the spindle height. It is more likely to be an 80s tbird with a a balljoint adapter where the strut would normally bolt on. Is the bolt circle 5 x 4.5, 4 x 4.5, or 5 x 4.25?

If it is an 80s tbird, I suggest using an 80s 4 cylinder mustangs spindles, calipers, and rotors (4 x 4.5). The rotors are smaller in diameter, so the weight is less, plus the weight is reduced where it will have the most effect. Pedal effort will increase and the brakes will get hotter under the same circumstances.

You can have the rotors drilled, surface to minimum thickness, and deburred to reduce the weight further. You could do that with the rotors you have now. The holes reduce the heat sink more than they aid cooling, so the rotors should run hotter.

You can adapt Willwood calipers to fit the rotors with custom brackets.

Another option is to machine off the rotor from the hub, press and turn a concentric ring, then use a slip rear rotor with the same bolt pattern and make brackets to fit matching calipers, but that adds up too.

Willwood and Baer make/made drag racing sets for the 80s mustang, with aluminum hubs and nonvented rotors but they are expensive.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
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Since the rotors barely get warm, make use of that wasted thermal capacity and turn down the OD of the rotor to decrease weight. Probably an easy 20% weight savings.

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The bolt pattern is 5 X 108mm (4 1/4" ) from the MN12 T-Bird.
Turning down the outside diameter will certainly reduce the rotational inertia and the "hat" could safely be thinned as well. I would prefer non vented discs as found on most Caterhams etc, though. On a car as light as a Seven, a low unsprung weight is certainly important.

I see. 91-93 tbird spindles cut off above the sway bar attachment, then use the swaybar attachment point for a uca and load the lca.

Solid rotors would also require new calipers or spacers, depending on what you have.

There probably won't much area to remove that isn't swept by the pads. Moving the caliper inboard with a new bracket may work if there is extra surface area behind the rotor on the spindle side. You could use calipers with a smaller pads, then move them inboard and cut.

Install the ford splash shield on the spindle. You can tweak it a bit to reduce the air flow over the brakes.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12

How about a Taurus SHO rear rotor? 10 lbs vs. 15.

Bill

Sorry, I should have added that if the rotors are cut down, smaller calipers can and should be used for even more weight savings and to best make use of the swept area.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

Just to bug people, my buddy showed me a set of all-aluminum SHO (I think) rotors. He claims only a couple sets were ever made... Those things weighed about 2 lbs, if that.

_________________
Midlana book: Build this mid-engine Locost!, http://midlana.com/stuff/book/
Kimini book: Designing mid-engine cars using FWD drivetrains
Both available from https://www.lulu.com/

I've seen vented rotors in an oval track catalog that weighed around 3 pounds. I'm pretty sure they cost a metric boat load though.

Ford Escorts had small vented rotors that would be light. You could put in Mustang II spindles and get lots of choices including Pinto disks. Do you have a budget for this? The Caterham spindles ( or Spitfire ) would likely save you 5 lbs. a piece too.

So look for a set of Spitfire spindles, disks and calipers and then modify what's required.

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
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Are you sure the benefits will be worth the cost and effort involved? To the best of my knowledge there are no easy direct bolt on options for what you want. So it's going to require custom machining/fabrication, purchasing new parts, or more likely a combination of both. Plus it's going to screw with the bias of the braking system relative to the rears, likely resulting in even more additional cost and effort to bring balance back to the (braking) force.

Since they were designed to be marginally adequate for a car ~4x the weight but ~1/2 as fast, and considering that the energy effect of velocity is squared, maybe you just need to use the brakes more aggressively and with stickier tires.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Not that it makes a difference in this situation, but why would you want to reduce airflow?

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Noah

... to make the brakes run hotter.

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Warren
Isuzu Pickup/SR20DE, +401 COLD frame
Build Log: viewtopic.php?f=35&t=11601

yes but ptrxly didn't say his cool brakes weren't effective, just that it meant they were unnecessarily heavy

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Noah

Volvo 240 has the same bolt pattern. They are 10.8 lbs unmodified for the Vented ones.
Solids are about 9.5 lbs. Don't know how the offset matches up but you will have to run some kind of adapter. The RX7 Turbo genII calipers are very good an pretty light. still not willwood light.

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Volvo 240/P1800 Based Locost
2004 Aprilia Mille Factory
1988 Volvo 240 5 Speed ( For Sale)
2002 Toyota Tacoma
1999 BMW M3

He initally stated a desire for lighter brakes, that are unvented for less air flow, and the justification was the brake temp after a session.

It isn't a stretch to consider that maybe a person concerned about track sessions in a custom built car will have "high performance" compound pads rather than oem compound pads. Such pads frequently do not perform as well as oem pads at lower brake temps, so if there is no lighter, cheap rotor available, then reducing cooling flow for the hi po pads to work better is an option or just revert to oem compound pads.

_________________
Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12