any feedback on Mazdatrix 5.5" race clutch?
 

i'm looking get Mazdatrix aluminum flywheel and quartermaster 5.5" twin disk clutch. please give some feedback if you have used this setup or similar setup for road course. thanks

Does this use a stock slave cylinder and throw out bearing? I was under impression all the multi-disc setups used hydraulic TO bearings... if not then that is awesome and I may look into this setup closer if you have good luck with it!

AFAIK it use stock slave cylinder but I'll contact them and check. It use a standard throw out bearing but it's specific for the setup and cost $170.
https://cimg4.ibsrv.net/gimg/www.rx8...37b3b9aed1.jpg

Interesting, I guess if they make a TO bearing that interfaces it then that works.

It's only about $80 more to go with the hydraulic setup though, which may prove to be a better long term solution in race applications. I wonder if you could take measurements off of that one Mazdatrix sold and find a cheaper interchange part though... looks like a pretty standard assembly.

I contact them and confirmed that the setup is designed for the stock hydraulic system.

Also the TB is a custom piece. It's as small as possible to get the most leverage on the diaphragm. The retaining clip in the back is custom laser cut and fabricated to the bearjbe. You won't find and off the shelf unit that will work. Im hesitant to use hydraulic TB because if there's any issues with it you gotta drop the tranny.

Ah okay, I didn't realize it was custom made. Let us know when you get it all together, I'm curious how that setup works. I'm looking at making the jump sometime in the next few months... gotta get the diff back in the car and make sure it isn't going to explode first though.

subbed for review

I got the new clutch in over the weekend. It's the easiest tranny i ever had to remove. Took about an hour to remove it and I was taking my time since it was my first time on this car. Getting it back on is a different story. Took about half an hour just to fight it to line up both disk. Had to pull the tranny out a couple times to make sure both disk were still lined up.

Didn't drive it the road yet because we're working on a new muffler. I did drive it back and forth in the shop. It's noisy with the clutch disengage and it chatter like a mofo on take off, as expected with any multi disks race clutch. Rpm drops crazy quick. The clutch pedal is significantly more heavy. I haven't try to adjust the pedal travel yet. But initially, the pedal went to the floor. I and to hand pump it several times for the pedal to come back up.

https://cimg1.ibsrv.net/gimg/www.rx8...f0b8ea08a2.jpg

https://cimg2.ibsrv.net/gimg/www.rx8...fbde4dbec4.jpg

https://cimg5.ibsrv.net/gimg/www.rx8...ef9cad52d4.jpg

https://cimg8.ibsrv.net/gimg/www.rx8...bd71b4bf1e.jpg

https://cimg3.ibsrv.net/gimg/www.rx8...bc3d61ecca.jpg

https://cimg4.ibsrv.net/gimg/www.rx8...6c28691ea5.jpg

Looks good! Think you could still drive a car up onto a trailer with it?

i'm going to try to drive it on the trailer. slipping the clutch a little while its cooled shouldn't hurt it too back. a few guys ive talked to that use this clutch on different cars said they drive it on the trailer, but their engines also have lot more torque at low rpm. i'm prepare to get an electric winch if i have to tho.

Does this weight block on the tranny serve any purpose other than to reduce noise and vibration? I want to remove it to cut some weight.
https://cimg5.ibsrv.net/gimg/www.rx8...253a3583fd.jpg

Mazda just lists it as "Dynamic Damper" on the parts listings... I'd guess it's safe to pull off. I'm curious how much it actually weighs, I've never given the thing two thoughts.

This setup revs super fast. With a stock 1st gear, it should not be too bad. Plan on using the starter a few more times until you are used to it. Heel toe downshifting will take some getting used to but it's nice once you are there.

I drove my 2nd gen with this setup on to the trailer for years, that had a tall 1st gear. I ended up getting an electric winch, but waited 3 years to install it so it couldn't have been that bad!

This is awesome on the track, but would be a PITA on the street.

Steve

nice thanks for some feedback. i'm also installing 5.1 FD also, so 1st gear should be pretty short. how did heel/toe change? need to rev engine more and shift quicker?

We used the 7.25" version of this for a bit before switching to Tilton, while using the same style flywheel you have. We had significant issues with the QM unit that they could not diagnose. Especially when hot, it would drag like crazy, to the point it would nearly stall the car trying to put it into gear with the clutch in. Lots of 2nd gear grinding issues too, for the same clutch drag reason. We ended up replacing everything in our clutch system including the transmission, and went through multiple QM clutches trying to figure it out... before finally pulling the clutch out.

Ultimately we figured out that Mazda's input shaft is slightly over industry standard (not QMs fault, aside from not being able to give us the specs to check if that was the problem). We had to lap the clutch splines to give it a little more clearance, so it wouldn't bind up, and also used a very small amount of lube despite the instructions saying it must be totally dry. I would suggest you check yours for any bind before installation... but looks like I arrived a little late to the thread.

The QM units were also never well balanced and always had a strange resonance around 3500rpm for us. The Tilton is balanced (has specific markings to indicate which order and clocking direction to install the floaters based on their in-house balancing) and thus our resonance issues went away, and their engineering team was better at helping us diagnose and solve the clutch drag problem. It also has smoother engagement for driving around paddock. It's been a great unit and I would highly recommend them for both the quality product and their engineering team.

We use a winch. These clutches don't like slipping and will wear out much faster if you load onto a trailer without a winch.

yeah unfortunately i already have everything back together. the spline issue is probably what i was experiencing when i had trouble putting the tranny back in. it slid on the first disk fine but seemed to get hung up on the second disk. i guess i'll pull the tranny out again to check the clearance and lap the input shaft if needs to. thanks for the feedback.

There is very little rotating mass with this set up. On your down shifts, the throttle blips will be almost instantaneous and RPM will be higher than needed until you adjust. At Road America, I would come into T 5 in 5th gear, blip and go right to 2nd every lap. Like butter. Once you get used to it, you will love it.

I've run the Quarter Master 5 1/2" for 10 years and never had any issues. I use a "sawn off" input shaft as a clutch disk alignment tool so maybe that has something to do with it never hanging up when I pull/reinstall a tranny.

Don't forget about the angle of the tranny compared to the engine when installing. That inch or so between the clutch disks means it has to be dead nuts straight to go in. A little wiggle to get it to slide in is common. If you have the tranny/input shaft installed, why take it apart? Maybe I am wrong, but I believe a spline shaft is not supposed to move. Too much wiggle bad, too little is a pass/fail matter of getting it to slide in.

i used a plastic clutch alignment tool, they aren't the highest tolerance. Tamra gave a good suggestion, insert the tool and turn the disk to make sure both disks are lined up on one side of the tool. did you have issues with the oem input shaft being slightly over sized and bind up on the disks like Tamra did?

I've never had a problem but there is little if any tolerance using the steel input shaft I have a Team Support number with Mazda and get the clutches through them, not that it should matter. I have never heard any complaints about Quartermaster and that's what Mazda Motorsports stocks and sells. Not saying is did not happen, just news to me.

Making sure both disks are lined up on one side of the tool makes sense if you are stuck with that alignment tool. I assume you are torquing the bolts partially, then fully in a proper patter while the tool is still installed.

wow i didnt know that you can get QM through Mazdamotorsport. I have a support number and could have gotten it for cheaper. how long does a set of disks last you.

Mine last several seasons even driving it on to the trailer but it depends on a lot of factors. I trashed one on a chassis dyno that bolts to the rear hubs, never ever happened on a roller type. I just went to a PBS dog ring box so I only use the clutch to get out of the pits so I'm starting over.

Hi Tamara,

I've never lubed an input shaft. As a disclaimer, I had been running a 13b in a 2nd gen RX-7 in SCCA E Production. I bought the RX-8 in October and am replacing the Renesis and Mk II box with the RX 7 drive train. I believe I'm the first person in SCCA taking advantage of the new rules allowing a ported 13b in the R-8 chassis.

That being said, I'm not using a stock synchro box. When I went from ITS to E Prod, I started with a dog ring box built by Ron Olsen that fits inside the stock gearbox, then went to the stock synchro setup with close ratio Emco gears. After that I ran a close ratio box built by Jesse Prather with synchros and straight cut Houseman gears. Now I'm using a PBS dog ring box.

My new RX-8 has the 5 1/2" quartermaster and lightweight flywheel, stock gearbox and 5.12 rear diff. It's fast, and smooth through the rev band.

I'm glad you got it worked out. Where do you race? I'll be at VIR in April then again in the fall for the Runoffs.

too bad you dont race with NASA. i primarily race with NASA and go to VIR at least twice year. I mostly run in northeast tracks.

Watkins Glen is on my bucket list

Glen is an awesome track. scare the shit out of me but i love it. check out PittRace also, I think i like that more than Glen now.

so after getting the car back together, i start the car up and let it warm up. then it push the clutch down to get it in gear and the car would lurch forward and doesnt want to go in gear, i tried several times in different gear and its the same. i even put the car in gear and try to start it in gear with clutch down and the car would lurch forward. so the clutch is definitely dragging. i couldn't figure out why. then i tired something else. with the engine running, i put slight pressure on the shifter to put in gear, then press down the clutch slowly till it slide into gear. boom. that's when i realize that the over travel of the pedal cause the clutch to drag. the clutch has a very narrow window of disengagement, anything over that would cause it to reengage. i had already made a pedal stop but i didnt have it turned out far enough. i end up having to turn the pedal stop out so far, for the perfect clutch release, that the clutch pedal wouldnt engage the low switch to start the engine. i had to add a half inch spacer just so the pedal could engage the low switch to start the engine. i probably took about half of my clutch travel out. which is great, less clutch pedal travel

the clutch grabs like crazy, but can still slip if you try, doesnt chatter much. there's no engine momentum at all when taking off from stop. rpm drop so quick between shift. and if you take it out of gear coming to stop, rpm drop so quick then engine stalls out. gotta keep it in gear till rpm drop low enough then take it out of gear.

Yeah, they have a very narrow window of adjustment that is acceptable - about 1/4" actually. You have to be careful, because if you overstroke the pressure plate it will mess it up. Follow the instructions carefully.

That is a separate problem from clutch drag, however. If the pedal isn't adjusted right and you have too much travel, you will actually re-engage the clutch, which is what it sounds like happened for you this time.

Yeah definitely wasn't clutch drag but clutch re-engagement. I haven't driven the car hard and shift at redline yet. Still taking it easy to break in the new 5.1 FD and osg diff.

Fast Rev
 

I had mentioned that the aluminum flywheel and 5.5" clutch revs super fast. I found one of my blooper videos where the lighting was just right so you can see my feet and the throttle blips.

I figure its worth showing

nice, yeah i'm pretty decent with heel/toe but i dont think the throttle by wire react as fast as cable throttle when it comes to a quick throttle blip.

Is there any truth to this or is it just how you feel about it?

i had my first track event last weekend with the new clutch setup. the clutch felt amazing on track. shift was lightning quick and effortless. can feel the synchro doesnt have to work very hard, with the low inertia of the small disks. also probably because the rpm drop so fast that synchro doesnt have to do much to match the speed of the disk to the engine. getting the car moving from a stop is a pain. have to rev it up pretty high and ease off the clutch or it will stall. idle is also not very stable sometimes. i did drive it on the street for about 300 miles to break in the clutch and and final drive. definitely not DD friendly. getting on the trailer is not as bad as i thought. i pull the car up the ramp to line it up. then back up about 5 feet and get a running start up the ramp. didn't have to slip the clutch much. if you're car is primarily a track car, i would highly recommend this setup. it would probably make the tranny last longer also.

my tranny was grinding going into 5th at the last event last year. and i never had to use 6th on track. with the new clutch setup, i can bang into 5th without any issues. and getting into 6th is a breeze also, which i have to do a lot now with the 5.1 FD.

here's a short vid from last weekend.

Nice driving man, I can see what you mean. I'm going to have to pick your brain when I start my "24 Hours of Lemon Racing" thread in here when my Noob 30 days are up so I can start a thread. Your temp looks pretty solid.

Generally speaking, when you go to the smaller clutch sizes the PP doesn’t need as much actuation/pedal travel. Most of the mini PPs need a pedal stop added to prevent overthrowing & damaging it. So the thing to do if possible is to swap out to a larger diameter slave/release cylinder.

This not only decreases the amount of TB throw relative to pedal travel, it also increases the applied force to the throw-out bearing pivot arm. Which in turn decreases the pedal force on your leg and is helpful with high PP spring rates. It also helps with the engagement/slip control when releasing the clutch to move/launch the car forward.

FEED/Fujita Engineering sells a 21mm slave to replace the OE 19mm unit for this purpose. You’ll still need a clutch stop on the mini-clutches. Also a bit pricey compared to buying the OE slave; around $210/shipped from JP.

https://www.japanparts.com/parts/detail/18736

I tried to find an OE equivalent to save money, but gave up and just ordered it from them instead. My car is still not running yet to try it out though. Common mod for FD3 RX7TT cars using stiff /multi-disc clutches.

good info on the larger slave to reduce pedal pressure and elongating the engagement point. The QM had a very stiff pedal pressure, so i'm sure a larger slave cylinder would have reduced that pressure. i switched to Tilton because they offered three different pressure plate force. i went with the lightest one they had. pedal pressure is just a tab stiffer than the gas pedal, it's awesome. i also had to make a pretty long pedal stop, so pedal travel is short, which is also great for me since i'm short and usually have to tip toe the clutch pedal to fully disengage, but with the pedal stop, i dont have to anymore.

when i put the car on the dyno, after only putting about 200 easy street miles on the new clutch to break in the final drive, i think the clutch was slipping a little on the top end for the first few pulls. i thought the tires was slipping on the drum but there's no way it would slip with only 130 torque. but after a few pulls, it stop slipping. my guess is the disks wasn't fully bedded in during break in.

maybe ill go with the medium pressure plate spring when it's time to rebuild the clutch. the lightest spring that i have is rated for 300 torque.

A strong Renesis engine will make around 190 lb/ft torque at the flywheel. These smaller clutch discs are going to wear faster than a larger clutch. When you use the lighter PP you’re more likely to get caught out with a slipping clutch between maintenance inspections.

For Tilton the stiffest high-ratio PP will allow for the longest disc wear before slippage occurs.

https://cimg1.ibsrv.net/gimg/www.rx8...d1faf39b86.png


If you’re running the 2-disc cerametallic then you probably want the 480# PP, imo. I pushed in the pedal with one on the std slave setup and it didn’t seem stiff to me at all. Similar to a stock clutch.

the clutch was brand new with about 200 street miles. so i don't think there much wear on the disks. it felt like it was slipping on the dyno for the first couple pulls then it stop slipping. the pedal fells very light, just slightly stiffer than the gas pedal. i plan on servicing the clutch at the end of each season. sooner if it's required. i do about 30 track days a year.

https://cimg1.ibsrv.net/gimg/www.rx8...cfc603304e.jpg

Well if it lasts that long. Not saying it won’t though. I wasn’t implying anything about the initial issue you had or anything else really. It’s just general information for anyone else considering going that route. Based on what I already posted, I’d imagine the 2-disc 300# PP feels a lot lighter than the factory clutch.

But to put it into perspective, on the disc wear vs torque capacity image I posted in the previous reply above; take that same green line and put it about 1/3 lower than where it is and that would be the comparison between where your 300# PP is compared to the 480# PP being the existing green line. That’s mostly what I was trying to explain and also that people shouldn’t necessarily think they’ll get a super stiff pedal making that choice. It might make it a bit more on/off, but the larger slave cylinder will help offset that and if for some reason the clutch discs wear you’ll have more torque capacity coverage before it slips.

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I have it On my 13B PP rx7
Love it really change the engine response

Here are old video of my with oldschool mazdaspeed fltwheel with 4.5 inch
But is similar idea

wow i cant imagine a 4.5" clutch. my engine revs insanely quick, and shift super quick. my s1 tranny felt really notchy getting into 5th, would grind if i shift quick. after installing the 5.5", the tranny felt great and i could powershift any gears without issues.

vid of my recent event.

It’s not necessarily quicker depending on what it’s being compared to. It all depends on the mass and how it’s distributed. It’s also approaching the zero-sum gain of % difference. Pretty sure that’s why Tilton doesn’t offer anything less than 5.5” for metallic. I’ve never seen QM post this info, but for Tilton comparison:

7.25” Twin metallic
Weight**: 7.5 lbs/3.4 kg
M.O.I.**: 66.3 lb-in2/.0195 kg-m2

7.25” Twin carbon
Weight**: 6.2 lbs/2.8 kg
M.O.I.** (Step): 52.81 lb-in2/.0155 kg-m2
M.O.I.** (Pot): 52.26 lb-in2/.0153 kg-m2

5.5” Twin metallic
Weight**: 5.7 lbs/2.6 kg
M.O.I.**: 29.8 lb-in2/.0087 kg-m2

5.5” Twin carbon
Weight: 3.7 lbs/1.7 kg
M.O.I.: 17.8 lb-in2/.0052 kg-m2

5.5” Triple carbon
Weight: 4.4 lbs/2.0 kg
M.O.I.: 22.0 lb-in2/.0065 kg-m2

4.5” Twin carbon
Weight: 2.6 lbs/1.2 kg
M.O.I.: 11.4 lb-in2/.0033 kg-m2

4.5” Triple carbon
Weight: 3.2 lbs/1.5 kg
M.O.I.: 12.3 lb-in2/.0036 kg-m2
.

When I don't have trailer back then, I use to drive this set up on street to track
To get my life a bit easier , I bought a Rally disc
Which is a bit thicker then normal road race disc

Did you happen to weigh the OE clutch? I can’t seem to find a weight for one anywhere and never thought to check it myself.

Just weighed my used oem clutch which still has a lot of meat left on it, came out to 16.2 lbs, disk and pressure plate.

I was assuming 15 lbs, so not far off. On page 1 you didn’t mention that you must also use the auto counterweight, which adds another 3.6 lbs to the overall combined weight of the race clutch/flywheel assembly

thanks

You are right, good point about the counter weight. That weight is pretty close to center tho. The rev is insanely quick.

Yes, but it still adds static weight on the scales :)