Wow, you are making great progress! Here are some images to some of the torque values that you need. These came from the Gen 3 SR8 owners manual. Radical recommends using the latest manual because they are always updating the information as they learn more about the cars.
Charley
Geez Richard, you don't mess around! Nicely done. I'm just back from a track weekend, and will be taking stock of the car, including a thorough review of the brakes.
Brakes installed:
Was advised by Mark at SMR to redirect the cooling ducts from the rotors to the starter on the left hand side of the engine and the other towards the bell housing.
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming 'WOW-What a Ride!'"
Not a good day at the track.
Overfilled the oil system and dumped about pint onto the diffuser and ground whilst going through warm up. Crap.
Got the overflow tank level down to a workable level - but... Didn't have the correct tools so it was a lot of McGivering with fuel tubing and plastic bottles. I had one "poof" of blue smoke join me in the cockpit just before spinning at the end of the straight - pretty sure my McGivering failed.
On the way back into the pits I hear tink, tink, tink. Hmmm... Something feels like it just got caught in the left rear.
I get in and there are a couple of the brake mounting bolts missing. They've let go. Quite a few of them are loose and I'm not sure why. The one bolt I did look at appeared to be pulled apart where the nut was. I got grade 10.9 bolts so that shouldn't be the issue, should it? I never got things hot enough to do any serious expansion or the likes. Must say that the steel brakes have really nice modulation and a much better feeling at the pedal than the carbons did.
Not in the mood to mess with things presently - it's back in the shop, covered in dust with a pee pad underneath it. I'll CSI it later - already know I need to order floating hardware so that'll be the first step. I am curious as to why the bolts (or possibly jet nuts?) let go.
Arrrrgggghhhhh. Suffering from no fun and decently high frustration level presently. I'll go for an off road ride and reset my pea brain back to it's normal happy self. - plus we're headed to dinner at a really good place with really good friends tonight so the day won't be a bad one.
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming 'WOW-What a Ride!'"
Sorry to hear about your bad day at the track. I had a great weekend last week, but my gearbox has me a bit down today. 🙁
I've pulled my front rotors and calipers off the car and compared various measurements to the Wilwood catalogue. There's no easy way to swap over without replacing the uprights, or at least cutting the caliper mount ears off and moving them out and over about 35mm. The mounting distances of the calipers are quite a bit different. Really, the only thing that's common is the 5.25 mounting distance between the mounting lugs.
I'm dropping the Wilwood idea and will just put on new Radical rotors and pads.
Roughly 3/4 of my fasteners failed and of the 40 only four were still tight.
The 10.9 grade 6x1.0mm bolts have sheared off (and/or a few of the jet nuts have cracked in two) right at the back face of the disc's mounting ring. The loose, but still having nuts on them, bolts have failed in the threads right at the base of the nut.
10.9 bolt has a tensile strength of 150,000 psi which works out to about 4,800 lbs of force required to pull a 6mm bolt apart.
All bolts/nuts were torqued to 96 in-lbs (5 ft-lbs), all the floating setups allowed for the square floater piece to move and the bobbins were securely fastened to the rotors. I seriously doubt heat and expansion caused the issue - never got the brakes hot enough to do so. I'm a tad puzzled.
Will moving to a 12.9 grade (170K psi) solve the issue? Dunno? I believe that the OEM hardware is a 12.9 grade.
Being that the failure is exactly the same across the board there's obviously some very specific point that I've managed to not take into account (miss). The bobbins, with the large "washer" area, quality fitment in the disc, the floating hardware and how it mounts in the hat shouldn't allow for any torque style loading on the bolts - they really shouldn't do much more than hold the bobbins in place while the bobbins transfer the load between the rotor and hat.
I know there are other engineers (aerospace guys) here on the site - wanna throw out any thoughts you may have?
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming 'WOW-What a Ride!'"
Richard -- I wonder if you should have your torque wrench calibrated? That failure rate sounds like over-torqued bolts to me....
While I won’t argue that idea (have already entertained it) I will say that 5 ft-lbs of torque is minimal, the feeling of doing the torquing was minimal and overly tight just doesn’t seem to be the obvious culprit.
Think it’s possible that I did get enough heat in them to cause enough expansion to cause an overly tight situation? I have a hard time believing that I did with the minimal running time I got in.
I tried to keep my tolerances, where the shorter side bobbin pin goes through the rotor mounting ring, at about .005” clearance so the bolt/washer/nut clamped the bobbin to the rotor. My first round of cutting them left them proud by about .010” and allowed for the assembly (bobbin/bolt/washer/nut) to pivot in the rotor so both ends of the bobbin floated, which I would think is not ideal and could lead to binding issues.
Interesting observation regarding the carbon discs - the hardware was tighter than 5 ft-lbs (not measured but I know they required quite a bit more grunt than that to remove), the washers were much larger in diameter and were deformed where they’d been pulled into the mounting hardware. They also had a much longer bobbin protrusion in them than the steel setup.
I really wonder if it’s just a case of not a strong enough bolt?
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming 'WOW-What a Ride!'"
Yes -- it could just be the bolts aren't good enough. Is putting in 8mm bolts an option?
I don't believe there's enough room in the bobbins for an 8mm bolt - checking on the previous page it shows the through holes for the bobbins into the carbon rotors is a 9mm hole. That's getting oh too thin.
I'll look into ordering a set of grade 12.9 bolts and nuts and see what happens.
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming 'WOW-What a Ride!'"
Richard,
you may have assembly error. I was taught to use 242 loctite on clean new bobbin/fasteners. That increases the 5ftlbs torque because fastener is lubed by the loctite. I have never has a bobbin come loose. I have reused old hardware on occasion too but I am careful to clean the hardware well.
I have not done radical rotor so ymmv
Howdy guys, been a bit. Track season here is on the lam so I’ve parked my little blue beastie for a moment.
Hey John Parsons I got an e-mail from HiSpec regarding rotors:
Hi Richard
Sorry for the late reply to your enquiry.
I have just received this from our tech dep't:
Yes, we are the oem supplier for all of Radicals brakes. But the 1 thing we never made/supplied was the carbon rotors.
Radical found a source of carbon rotors & asked us to develop a caliper to suit.
We could produce/supply for you standard cast iron rotors (along with new centre bells & pads)
The only problem is that as we never saw the carbon rotors we have no data to re-produce them.
Option 1) you could send us the rotor & we measure it, copy it & send it all back to you.
Option2) you could measure it all up and send us a detailed sketch/design for us to produce the parts from. (this is a little tricky as there are a lot of small details that can cause big problems if they are not right)
Let me know what you think and we can take it from there
Kind Regards
Paul
Sales Department
HiSpec Motorsport Ltd
I got into a cleaning mode a week or so ago and tossed my carbon rotors into the trash bin. If I’d gotten this earlier they’d be making rotors for me.
If you still have your carbon rotors I’d be in on option 1 and would be happy to split shipping costs with you if you’d run with it.
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming 'WOW-What a Ride!'"
That sounds like a good opportunity!
Hey Richard -- neither of my cars have carbon rotors. They both have the 280mm floaters (but with different hat designs). If I had the carbons I'd happily send one over there. Sounds like Hi-Spec will be willing to help us on brakes without going through Radical, which is probably good news for owners of older cars.
John, I was under the impression you had carbons from your first post in this thread. No worries.
Looks like Charlie May have access to a carbon rotor for me to borrow and send to HiSpec. I’m going to respond to the email they sent me and see what the next step is. I’ll keep this thread updated as I find out info.
"Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming 'WOW-What a Ride!'"
