DWS44

Obviously...this guy does:



Just no granny shifting!

JerryU

Now the synchro rings have bonded linings and in the M7 with three, one is carbon faced.

Sounds like you might enjoy this video! He talks about the old standard transmissions but also shows a double synchro in a Tremic!

He goes into detail on what the synchros have to do in a very, very short time.

Even an old gearhead like myself enjoyed it! May have to watch it twice!

3 Z06ZR1

Halltech just came out with the Stinger intake for the model A's!

Emerald Eagle

Yep, hard habit to break.
My first car was a MG TD, which I drove today, responds well to the double clutch. Also my series 1 E-Type requires the fancy foot clutching to get through the box.

I agree that the C-7 shifts like a dream but I still double clutch when the rev match is off.

walleyejack

exactly, speeds the clutch up to match flywheel speed, and drops into gear much easier, without hearing the whine when one tries to jam it in.
Revmatch does not do this, all it does is speed engine up to match rear wheel speed.
been saying this for years, but people don t understand how the transmission and clutch work.

Foosh

ARM does perfectly match engine flywheel speed to clutch pressure plate speed. Clutch pressure-plate is disengaged and spinning at a rate corresponding to rear wheel speed, shifter moves to lower gear gate, ARM matches engine flywheel rpm to the corresponding speed for that gear and spinning pressure plate, clutch is re-engaged at a speed matching the flywheel speed.

When you downshift, the pressure plate is spinning faster than the flywheel when disengaged, so the flywheel must be spun up to match that speed. ARM does that. Otherwise, when the clutch is re-engaged, there is a more violent engagement, and that jerk you feel is the result of the flywheel/ pressure plate collision at mis-matched speeds, with the pressure plate mechanically spinning up the flywheel, and wearing itself out.

walleyejack

How can it be. The clutch is disengaged from the flywheel, tell me what is spinning it up to match flywheel speed then. Impossible.

Foosh

You're not completely comprehending how a manual transmission works. The transmission determines clutch pressure plate speed, and the throttle controls flywheel speed independently when the clutch is disengaged.

When the pressure plate is disengaged and a lower gear is selected during a downshift, the rear wheels/transmission are almost always spinning the clutch pressure plate at a faster speed than the flywheel when you're out of the throttle. Thus, during a downshift, the flywheel must be sped up to match pressure plate speed appropriate to the gear selected.

The pressure plate may be disengaged from the flywheel, but it's NEVER disengaged from the drive-shaft/torque tube/transmission. The transmission gear selected and vehicle speed in that gear determines pressure plate speed. The faster you're going with clutch disengaged, the faster the disengaged pressure plate continues to spin depending upon gear, and the flywheel must be spun up to match it appropriately during a downshift. ARM does that perfectly.

JerryU

Suggest you watch the synchro video I posted to see what they do just fine without your help! They spool up the cluster gears and do it perfectly not "close" as best you'll do! That is what they were invented for in the 1930's! Now with triple synchros on most gears in the M7 they do it very well with little wear! I even gave up my slip stick some years ago!

I seldom have Rev Match off as I find it does a better job than I can on low rpm downshift like going from 1400 rpm to 2800 rpm when making a turn shifting directly from 5th to 3rd! Have only driven standard shifts as my DD for almost 60 years and quite good at getting an excellent rpm match at higher rpm downshifts. However modulating the throttle to get a perfect match at lower rpms is not as easy!

Foosh

While the synchros allow you to shift the transmission into various gears smoothly, they do not govern the marriage between flywheel and pressure plate during each shift. What synchros do and rev match does are two different things.

Once the synchros do their job, the transmission spins the pressure plate to the appropriate speed for that gear, and then the engine/flywheel must be matched to that speed for a perfect marriage. It's the last part that ARM accomplishes perfectly every time.

JerryU

But the sychros accomplish what folks are trying to accomplish with double clutching which is spool up the gear clusters before meshing.

I contend the synchros do that better as does Rev Match the engine wheel speed match.

Metalgearsolid_x

Agreed. Owned a 370Z for 9 years. Yup, 9 years and 100,000 plus miles later - oem clutch, oem transmission are in flawless condition. The SRM (SynchroRev Match which is exact same this as ARM) worked beautifully and since it always rev matched perfectly, clutch and trans stayed brand new even after 9 year! Redline synthetic helped also imo.

TyBoo

Foosh, I am lost, here. Can you give me a quick primer on the clutch configuration in the C7, please? The last clutch I actually worked on had the pressure plate attached to the flywheel. I am old enough to remember double clutching and it has been quite a while since I put a clutch together. I guess things have changed a bit. Interesting.

Thanks!

Foosh

There's nothing fundamentally different about the C7 and any other manual transmission ever built in the sense that when you depress the clutch pedal to the floor, the pressure plate disengages from the flywheel. Thus, you can rev the engine to redline with the car stationary, which spins the flywheel up to max speed, but the car doesn't move until you let the clutch pedal out to re-engage the pressure plate and the flywheel.

When the car is in motion, the clutch pressure plate speed is governed by the transmission gear selected when the pressure plate is disengaged. Thus, the need for manipulating the throttle either with your foot or using ARM to match clutch pressure plate speed to flywheel speed when re-engaging the clutch if you want to be smooth, particularly on downshifts.

Plenty of people don't do that, and that's why there are so many jerky manual drivers and prematurely worn out clutch pressure plates.

TyBoo

I guess this is the part that has me confused. It would seem to me that the pressure plate is spinning at the same rate as the flywheel and the clutch plate speed is determined by the rear wheels.

Is the flywheel/pressure plate still attached to the engine and the clutch plate still on the transmission input shaft?

Foosh

When the pressure plate and flywheel are engaged they are absolutely moving at the same speed. However, when you change gears and depress the clutch pedal, you are disengaging the clutch from the flywheel temporarily, and they are no longer in synch without intervention.

The clutch pressure plate is always connected to the transmission, so when clutch pedal is on the floor, the pressure plate is disengaged from the flywheel, and the transmission is spinning the clutch plate independently of the flywheel, which is throttle controlled.

When mis-matched during shifts, you get jerky shifts. What may be confusing you is that the transmission is in the rear connected via a "torque tube", but the principle is still the same. Pushing the clutch pedal in disengages the flywheel from the pressure plate/transmission.

Yes, the rear wheels determine clutch pressure plate speed, but they are always connected to the transmission and pressure plate speed is determined by gear selected ONLY, when the clutch pedal is on the floor. When engaged, flywheel and pressure plate are moving at the same speed and turning the transmission and rear wheels in unison.

TyBoo

Maybe is is just semantics then. I've always considered the pressure plate to be the assembly with the spring fingers that force the steel plate to sandwich the clutch friction disc between it and the flywheel. When the car is stopped and the clutch depressed, what I always thought to be the pressure plate assembly turns with the engine and the clutch disc is not turning.

Foosh

Yeah, just semantics. The operative part I was trying to explain to some is that when the clutch is disengaged, the flywheel and clutch are moving independently, one controlled by throttle and the other controlled by vehicle speed and transmission gear selected. ARM handles the throttle part automatically to match clutch and flywheel speeds during downshifts, which is when mismatch is most problematic.

papillion

I don't have one.

JerryU

For those of us that have taken them apart and replaced in the past, we would see something different with a C7! It has a dual mass flywheel and dual clutch disks. Works the same fuctionally, actually better with the high hp and large displacement engine.





Pics Not From C7 But Parts Are Similar