ALF

How exactly does a clutch get glazed? My clutch is showing signs of glazing. It's a stage 1 Clutchnet a couple months old. I am pretty confident that I broke it in properly. No, I'm not a clutch rider. City driving during break-in was smooth and normal. Blah blah blah...in other words, no abuse AT ALL during break-in.

nfn15037

Im pretty sure glazing occurs when the clutch gets very hot. This could be caused by a lot of things such as: riding clutch, beating on/abusing a new clutch, etc. BTW, how long did you go easy on it? Most clutches, esp organic and kevlar full face clutches need like 1k miles to break in properly.

dyezak

Glazing on clutching occurs due to overheating. Over heating can be caused by more than riding the clutch or high RPM clutch dumps. If the flywheel was incorrectly machined it will not properly break the clutch disk in and allow it to slip constantly, and slipping clutch produces heat, and too much will cause glazing. Also, if your engine is making enough power that the clutch cannot hold it it will also slip leading to the glazing you are speaking of. Incorrect clutch installation (flywheel re-surfacing) will usually cause clutch chatter, easily recognizable, so I doubt it was that. Also, I don't think your engine is making too much power for the clutch (I see no sig with major power adders). So more than likely it was improper breakin or being abusive. If it was a Kevlar based clutch disk you should break it in a bit longer than an organic disk due to kevlar being a harder material. Organic disks can be abused after 500mi (plus or minus a little) and be just fine, Kevlar takes QUITE a bit longer. If you get a metalic based clutch disk you can just put the clutch in, rev it to 6000rpm and dump it, no breakin required . Although metalic clutch disks are usually reserved for high end race cars.

ALF

Thanks for the great info! I guess somehow my clutch was improperly broken in. Very strange...I drove like a grandma for 1k+ miles during break-in. I didn't mention that my clutch chattered during break-in. It has since gone away, but does that have anything to do with flywheel being improperly machined? What are the causes of improperly machined flywheels? Everything seemed fine when I had mine resurfaced.

dyezak

Well, if your clutch WAS chattering then what probably happened was improper machining of the flywheel. Most of our FWD cars have a "step" style flywheel. When the flywheel's surface is resurfaced the "steps" (raised surface on the flywheel that the pressure plate bolts to) has to be machined down also. There is a factory specification as to how high the steps are supposed to be above the surface, and each different aftermarket clutch has their own specification. Go with the step height that matches your clutch (stock or aftermarket).

What is going on in there is your surface of your flywheel has just been machined, and is now farther from the steps than intended. Your pressure plate can only push the clutch disk with sufficiant force for "x" ammount of distance, after that distance your pressure plate's holding power is reduced (that's why each aftermarket clutch has their own step specifications). Your clutch will slip, then grab, then slip, then grab, etc., producing the chattering effect.

How to fix glazing. Some people say that it is possible to fix glazing by having the flywheel resurfaced and the stepsize put to the correct height, put the clutch back in and do ONE high rpm clutch drop to remove the glazing from the clutch. The theory behind this works...but I'd personally get a new disk.


[Modified by dyezak, 3:35 AM 11/29/2001]

rioninja

Ahhh, gotta love my 6 puck ACT. I broke mine in on the way to the corner
I dont think i would ever go back to an organic disk, for the sole reason of not having to hassle with the break in. They arent that hard to drive.

nfn15037

Not that their hard to drive, they just break tranny cases, axles etc. I just pulled out my ACT 6 puck after it cracked my GSR case. Screw that, im sticking with kevlar or organic disks from now on, they are way easier on your flywheel too. Id rather have the clutch be the weak point rather than bust another tranny.

dyezak

Which pressureplate are you using with that disk? An ACT 2600 with a 6puck is WAY overkill for ANY *streetable* FWD car. An ACT 2100 with 6puck will actually hold more power than a 2600 with a street disk. In the NHRA ranks on the blown nitromethane monsters they have flywheels with only 4-700lbs of clamping force!!! The clutch disk is a sintered iron. They can get away with a low clamping force because the disk's friction coefficiant is so high and because they usually use dynamic pressure plates. Meaning as RPM's increase the clamping force increases from 4-700lbs to 2500-4000lbs. This is accomplished by placing weights on the pressure plates "fingers" so that cintrifugal (sp) force increases clamping force the faster the plate spinns. This allows those AWSOME high rpm powershifts and leaving the line without overpowering the tires...once the car gets moving and the tires can take more power the clutch is grabbing harder.

These are "Long" style clutches opposed to our "diaphragm" type clutches used in our cars.

rioninja

I'm just using a new stock pressure plate. Its still very slippable, so its not like i'm slamming it through the gears or anything. just takes a little more practice taking off in 1st.

nfn15037

Try that same disk with the extreme PP, thats the way to break stuff!

John

I'm about to get a new clutch... hopefully the ACT heavy duty clutch w/ organic disc will suffice... but what about a flywheel? any recommendations? i'm looking for the best option for H and F-series motors?

nfn15037

I just got an act HD/organic, i jut hot 800 miles and hit it a few times. Its very nice! I like it alot an would recommend it to anyone

dyezak

I can tell you a few things about flywheels, and you make your own choice. Flywheel's are basicly three things, first it's a means for your starter to rotate the engine to start it up. Second it's a friction surface for the transfer of torque from the engine to the tranny. Last it is an inertia compasitor.

The last two items are the only ones we are worried about, so we'll descuss those.

Friction Surface: All friction surfaces (reguardless of flywheel material) are machined steel. Aluminum flywheels have a replaceable steel insert, usually bolted in, for the clutch to grab. Stock flywheels (except in select vehicles) are obviously all steel.

Inertia compasitor: When your flywheel spins it creates inertia. Inertia is dependent on two factors, flywheel weight and flywheel diameter. Since you won't be changing the diameter of your flywheel, only the weight we will forget about that. If you have a heavy flywheel your engine will revv slower, but it will be easier to drive because of the "stored" energy in the flywheel, conversely a light flywheel will allow your engine to revv faster, but...if you aren't producing enough power, you may bog and stall on launches. Usually you want to keep a stock flywheel unless you are producing more than 1.5x the engine's original output, or if you reduce the weight of your car by 1/3.

EXAMPLE:
Stock cars spec's: 150hp, 2400lbs. 1:16 or .0625 HP:weight ratio
To warrant a lighter flywheel you would want either 225hp with 2400lbs or 150hp with 1600lbs. There are many variables also, but this is a good rule of thumb to go by when looking at buying an aftermarket lightweight flywheel.

So if your civic had a SOHC 1.6l engine stock in it with 150hp and weight 2200lbs, and you put a h22 in it with an intake and exhaust a lightweight flywheel would probably help. Remember, inertia is your friend, but if you have the power to spare, or your car is light enough you don't require as much of it.

John

should we be looking at horsepower specs or torque specs to determine the inertia? i know horsepower is a function of torque over the rpm band, but torque is rotating power... while my motor doesn't have a lot of hp, it does have much more torque than most other motors out there... and even more torque with NOS... but my car is a daily driver, so i'm trying to determine whether or not a lightened flywheel would be in the best interest for the performance of my car...

dyezak

You should look at HP not TQ for this app. Remember, TQ get's things moving (ie acceleration) and HP keeps them moving. We want to keep the flywheel moving, and inertia helps with that, so if you have low HP you need a heavyer flywheel than someone that has high HP. That's as simple as it gets...but vehicle weight comes into play also .

nfn15037

Why would someone with, say, a civic DX want a dlywheel thats heavier than, oy, maybe a turbo GSR? Doesnt make much sense to me. The throttle response would suck on the DX. I dont have a car with huge horsepower #s, but a lightened flywheel definately halps response. It doesnt make it go faster i dont think, but heel toe downfhifts are much better now due to better response. So, i would say a lightweight flywheel can benefit any car, and certainly wont make any car slower.

Suprdave

A 6-Puck Copper Disk with a Stock Pressure Plate is a Good Combo.

I have a Clutchnet Stage 2, which is basically the above.

I can slip when I want to, and it'll grab like a Beast when I need it to.

Only Downside is it squeaks when you engage, and shift.

Suprdave

rioninja

My last one squeaked when it was cold, but my current one doesnt. Who knows.
good setup though

ALF

You can eliminate the squeeking by lubing your throwout bearing. But it wouldn't hurt to just leave it alone if you can live with the squeeking.

dyezak

Why would you ever want a heavier flywheel? Let's go to the extreme's here just to make explaning this easier. Say you have a 6000lb car and a 100hp engine (hmm...sounds to me like a common mid sized tractor). Let's give this car a 2lb flywheel. Now, that 100hp engine is going to have good throttle response due to that light flywheel, but once the engine is engauged the engine isn't putting out enough power to really get that thing moving. More than likely it will bog and stall out. Now, let's give it a 50lb flywheel. The spinning inertia created by that flywheel is so large that that 6000lb vehicle will start moving with less of a problem.


OK, now lets go to the other end of the spectrum. A 1500lb car with 750hp. If we used that same 50lb flywheel here you would create excessive wheel spin due to the high HP and high flywheel inertia. Lower that down to a moderate 7lb (most full race flywheels) and you can control wheelspin or even eliminate it.

Now, when it comes down to real world senerios it get's more complicated and the only true meathod for finding what flywheel works best for you is trial and error. There is math out there that can point you in the right direction, but it depends on your specific combo, weight, hp and driving style. If you want to drive the car on the street you would obviously want a heavier flywheel than if it was a full track car, cause a full track car doesn't have to worry about part throttle takeoff and smooth acceleration.

Like I said when I started this flywheel explination...I can give you the theory, but you have to decide what's best for you.

John

would a good option be to get your OEM flywheel to be resurfaced enough to take off a few pounds? that way you can find an intermediary between having enough rotating mass, but allowing your motor to rev faster...

dyezak

Resurfacing doesn't take off very much weight. Although most machine shops will lighten a flywheel for you. This involves removing material from the backside of the flywheel, but talk to a machine shop first to see how and where they remove the weight. The only place you remove weight that actually matters is close to the edge, if you remove weight from the center of the flywheel it doesn't do squat to reduce rotating inertia (see my above post).

Oh yea, and keep in mind...a lightened OEM flywheel is going to be more prone to flywheel explosion due to reduced structural integrity. So continuous high RPM usage is illadvised, as is upping the revlimiter. Also, this meathod is not NHRA legal. Food for thought.

Last thought...an exploding flywheel will always murder your transmission and 90% of the time will kill your engine. I have seen them total a car out too (one huge chunk of a flywheel severed the unibody a-frame structure of a local car at an event a few years back). Plus it's common for bodyparts to become misplaced, your bodyparts. There are numerous accounts of people missing feet and a couple accounts of missing hands. Just picture a hunk of metal flying at you at over 500mph, not pretty.

Now that I have scared you and given you the bad news, the good news is that this has been common practice for many years and can be done correctly without any ill effects. Just make sure the shop you talk to is well versed in lightening flywheels...oh yea, run a scattershield just to be safe. I run one on my stock flywheeled Talon (I am not producing enought power to warrant a lighter one YET) to be NHRA compliant at all tracks.


[Modified by dyezak, 6:52 AM 12/1/2001]

nugget8000

I would just like to share my own experiences driving a 94 GS-R with I/H equipped with a 7.35 lb flywheel. It took about a week of getting used to, but I after that i ceased to notice it at all. I would recommend it unless you can't drive stick worth anything at all.

Also of note, the two people I have ever let drive the car were able to get it going just fine after stalling it on the first try or two, and after that they did just fine. These people are not experts or do they have a lot of experience driving. One has never owned a car and doesn't drive on a regular basis, and the other only owned a car for a year. You can handle it. HTH.