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trying to figure out some details for my Bike engine powered project (hopefully around 1000 lbs curb weight)

for the front i`m planing on rather huge brakes for such a light car (292mm x 16mm vented rotors with aluminum 4-piston calipers)

while drawing the rear suspension on CAD i asked myself if i really need two heavy rotors
if i only put small lightweight two-piston brake calipers on them.

how about one driveshaft mounted rotor with a single caliper (preferably with integral mechanical parking brake)

the positive effect on unsuspended mass would be huge ...


what do you guys think ???

any ideas on possible negative effects i could experience

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- Stephan -

If you use any kind of differential, no. ..
Solid (eg lincoln locker) Ya sure you betcha'.

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"There are times when a broken tool is better than a sound one, or a twisted personality more useful than a whole one.
For instance, a whole beer bottle isn't half the weapon that half a beer bottle is ..." Randall Garrett

Jack
most likely i`m going to run a "lockable" Auburn LSD (LSD mixed with a 100% E-locker) ... its expensive

but i rather spend the $$$ on a LSD/locker then on a reverse unit

talking about reverse ;
if i have to build a stout center driveshaft support bearing to support the rotor/caliper anyway,
i could easy add a small starter ring gear & starter motor for reverse at the same location

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- Stephan -

If you have any icy roads you can test the behavior of this style of brake pretty easy. ..
(on an ice covered road) Roll up to @ 40 mph then drop it in second and (without touching the brakes) do a closed engine decel. .. Wheeeeeeee

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"There are times when a broken tool is better than a sound one, or a twisted personality more useful than a whole one.
For instance, a whole beer bottle isn't half the weapon that half a beer bottle is ..." Randall Garrett

actually my DiamondT truck has a driveshaft brake

today when i was under the truck (swapping over to big tires and lowering the front suspension)
and looked up at the driveshaft brake i figured this could maybe solve the problems on my BEC

i`m thinking to may use a small "Bert" circle track racing transmission flexplate for the starter driven reverse ...
something like this:

http://www.ebay.com/itm/NEW-Bert-BER370-F-Small-Block-Ford-Internally-Balanced-Flywheel-IMCA-CircleTrack-/111262414385?pt=Race_Car_Parts&hash=item19e7c1b631&vxp=mtr

...and bolt it together with a vented rotor to a stub shaft that is supported by a bearing block ....

my target is a near perfect 50:50 weight distribution so my brake bias will be heavy towards the front
the rear brake is very secondary

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- Stephan -

The problem with considering copying the driveshaft brake on a medium duty is that it's intended to be a "standing" brake not a "service" or "foundation" brake. .. and a differential does it's thing irregardless of which end is providing the motive force. You risk extremely rapid changes in applied braking force per wheel as you steer the car or drive over changes in road surface.
But I don't see why you couldn't put motorcycle rotors on the inboard ends of the axle shafts and use motorcycle calipers, that would keep curb weight down, reduce unsprung weight and it should be real easy to make an rotor adapter plate if you use 930 style CV's.

_________________
"There are times when a broken tool is better than a sound one, or a twisted personality more useful than a whole one.
For instance, a whole beer bottle isn't half the weapon that half a beer bottle is ..." Randall Garrett

That sure looks like a nice piece, much nicer than the B&S flywheel option. What's the diameter?

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"There are times when a broken tool is better than a sound one, or a twisted personality more useful than a whole one.
For instance, a whole beer bottle isn't half the weapon that half a beer bottle is ..." Randall Garrett

This subject made me remember I saw this somewhere. And wouldn't you know google sent me back to this site. This link has some additional links sending you to more ideas, so I figure sending you there is easiest. Granted these are inboard brakes on the axles...the only thing I can think of that would be on the driveshaft that is not a parking brake is the stuff you see on 5 ton truck axles.
http://www.locostusa.com/forums/viewtop ... 4&start=15

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Brian

this is commonly done on FSAE and DSR's. They usually do it with a Quaife or Torsen diff. I dont know much about the Auburn unit, but I am getting educated on diffs for my latest build. Eaton has a nice unit as well. I have not yet figured out exactly what I am doing, but using a single rear brake is a definite possibility for my P2 car. I will likely end up with something that looks very much like the picture in the above post.
Paul

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Parts left out cost nothing and cause no problems!!

I have the same concerns as Oldejack.

I have a P32 mail truck with a large brake on the transmission outputshaft. It is just a parking brake and only works if both rear wheels are on the ground (open diff).

I've seen them on older bec single racers without a diff.

A high quality diff may be okay, but I'd avoid clutch or toothed type diff.

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Using the two thin disks on the inboard of the halfshafts gives you a lot more cooling area and good airflow compared to something in your driveshaft tunnel.

It's a good idea to combine an electric reverse and the emergency/parking brake disk though.

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Marcus Barrow - Car9 an open design community supported sports car for home builders!
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I've driven a few FSAE cars with one rotor on the differential housing. In all cases the differential was a Torsion Type 1. You can tune the torque bias ratio under braking and acceleration by making thrust washers out of different materials; it took some tweaking to get right but it wasn't too terrible as long as one wheel didn't lose 100% of its grip. I completely forget what material we settled on but I believe it was some sort of bronze. At one point Torsen had numbers on their site that correlated a torque bias number to the washer material.

The biggest real issue was the heat transferred to the differential. It is easier to screw up venting a chain driven differential than it is to get it right. With the rotor on the housing, we had to run grease since the oil would expand too much and find its own way out.

This is more theoretical but reverse loading the axles is a really bad thing. Think bending the paperclip left and right and left and right; if you only bend it left then back to center you can get a lot more bends before it breaks.

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-Andrew
Build Log
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thanks for all the responses

yeah .... i guess the driveshaft mounted brake is probably not really a good idea.

Andrew

yes, i had similar problems on some quickchange IRS cars where i mounted the brakes "inboard"
(with a adapter plate to the 930/935 CV flanges)
the heat transfer to the CV`s was a huge problem


i just found fairly light OEM rotors with integral hat that fit my lo(w)cost needs (cheap, fairly light, easy available )
so i guess i stick with what works instead of trying to solve problems that are not there

oldjack

i could not find a diameter measurement anywhere ... but judging by the (SBC crank) bolt pattern i guess od is around 6-7 inches ?!?
i may still use that flywheel in some kind of a home made reverse contraption

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- Stephan -