'87 turbo II

iTrader: (1)

I am going to be doing a clutch job soon on my GSL-SE 13B powered GSL. I have the stock S3 13B 23 pound flywheel (a spare one that is gonig in the car to replace a cracked one that's in there now). I have access to a lathe at school and I was going to resurface it about 16 thousandths of an inch on friction surface. I was wondering if this was a good idea, or if I should just let a shop do it as I could mess the flywheel up. I heard whatever I take off the friction surface, I should also remove from the surface that the pressure plate bolts to, as it will keep the actual clutch plate itself the same distance from the friction surface and I will not be losing that little bit of extra pressure from a tighter tolerance. Now here is a stupider question. My friend suggested trying to lighten the flywheel, even a few ounces at the farthest edge of the rotating mass would help. I was wondering, as long as I didn't touch that asymmetrical lip (I think that's the integrated counterweight), and if I came in with the cutting tool at an angle, I could pull maybe a half inch to one inch groove around the outer edge of the flywheel (between the starter teeth mesh area, and asymmetrical lip that I believe is the counterweight casted on the flywheel. I was wondering if anyone has done this, and where the best places to pull weight from would be. Or if this is a bad idea to try. Any idea.

Neither of the pictures below are mine, as I just googled them,so the flywheel may vary.

I was thinking to machine everything highlighted in green down .016 inches for the actual resurfacing, is this the standard way to resurface? If there is no way to remove those pins that jut out, I was told I can just sand the surface area in the middle, will this work and be sufficient and save me the whole machining process?



Then I was thinking a 1/2 inch to a 1 inch deep groove where I highlighted here in green as well.



I figured since lathes machine circularly, I couldn't really throw the balance off unless I machine something that isn't symmetrical.

Crit

iTrader: (6)

There are a few issues I see. First off, why 0.016" I'd cover the friction face with dykem and make slow passes until it's all removed, then stop. What little bit you remove will be more than made-up with your new, thicker clutch so I wouldn't worry about engagement. Further, how would you resurface the flats, as the three dowel pins will be in your way on the lathe.

As far as the peripheral lightening of the flywheel, I wouldn't do it. Because the holes on the flywheel are drilled to balance it, you'll throw the balance off by machining. Probably not much, but who knows. You won't be able to remove the volume of the holes, so the previously-heavy side that got the holes will again become the heavy side. Is it significant? My gut tells me no, but then they wouldn't have bolted up a counterweight, spun the thing, and drilled the holes if it was insignificant.

'87 turbo II

iTrader: (1)

Ahh I didn't even notice the holes and like you said, if they're there for a reason I shouldn't mess with them. And I wrote up everything forgetting about those pins THEN looked up the pics and was like.... never mind haha. The .016 " is the number I read for resurfacing brakes somewhere so I thought I might try that. A ghetto flywheel diet seems like a bad idea the more I think about it so I think I'll just resurface the friction area like a normal person. The dykem and removal is also a smart idea, I knew you'd be who I wanted to chime in! thank you.

Crit

iTrader: (6)

Well, brake lathes are usually looking to turn the rotor that's been warped, and they're trying to get all the runout out of it. You just want to resurface, so I'd throw that 0.016 out the window. Go until it's all fresh steel, no further. In fact, I'd be tempted to start with some steel wool and work by hand on the lathe. If you don't get it chucked up dead square, you'll end up machining it out-of-plane. If you've got someone experienced looking over your shoulder then it's not such a big deal, but I wouldn't want to put a cutting tool to my flywheel on my first time ever on a lathe.

'87 turbo II

iTrader: (1)

Haha yeah, I've only ever made a bolt or 2 on the lathe before, but I definitely want the power of the lathe motor even if I am sanding by hand over just sitting there indian style with a 23lb flywheel in my lap and a lot of arm movement haha.

Vierte

iTrader: (2)

please pay $30 to have a professional do the resurfacing. first hitting the bolt pads with a hardened lathe tool at high speed is probably a bad idea. second using hand tools (sanding) on a metal lathe isnt the best idea either. any idea what would happen if you got your knuckle into on of those bolt pads while its spinning?

the preferred method of surfacing a flywheel is by grinding, not cutting. when you cut with a lathe tool hardened spots (hot spots) will not cut as easy and can lead to an uneven surfaced flywheel.

talk to your mill instructor about the process, he should be more knowledgeable then most people here.

by the way the pins pull out.

'87 turbo II

iTrader: (1)

If I set the RPM to 115 I doubt I could hurt my hand on the lathe so long as I didn't feed it into the starter gears and have it ripped up on the rails that the tailstock slides on. I could see the curring tool being a bad idea, and it would be really bad if I cut into a new plane. Lathe aided hand sanding won't work?

bwaits

iTrader: (12)

Take it to someone who has the equipment to do it right. They will not machine the bolt pads, just the friction surface.

Use that extra lathe time to make yourself a shift ****.


-billy

Vierte

iTrader: (2)

no matter how good you are at hand sanding, it will not give you a flat surface. thats kinda the point of resurfacing the flywheel - you end up with a nice flat rough surface for your new flat clutch to stick to. to add to that when a clutch is surfaced the tooling marks cross the frictional surface which would be different from hand sanding where the tooling marks follow the frictional surface.

just have it surfaced by a shop, you wont regret it, they may even do the bolt pads. you will end of with a clutch that feels absolutely brand new.

Twilightoptics

iTrader: (1)

You need a surfacer to do this. You need to pull the dowels. First measure the tickness of the flywheel at the friction surface. Then use a FLYWHEEL turner to turn it down until you see fresh metal. Then re-measure. The difference of the thicknesses is how much you need to turn down the bolting pads. Again with a flywheel surfacer.

NOT A LATHE. You'll spend hours chucking the flywheel up in the lathe and dialing it in true. THEN there is a good chance once you start working it with the lathe, you'll knock it out of true. PLUS most lathes have a left/right feed... not an in/out feed. So you'd probably be doing it by hand, which isn't a good idea in this application.

As others said, spend the $30 and take it to a pro.






I keep seeing people say they wont machine the bolt pads. That's incorrect information. The bolt pads much be machined to keep proper claming force on the disc itself. The farther in the pressure plate surface is, the less clamping force there is. Think about what happens when you bolt it down. The disc loads the pressure plate in clamping force. If the two are farther away because the bolt pads weren't turned, the the clamping force is reduced. It doesn't take much to make a good sized reduction.

Banzai

iTrader: (13)

If you realy want a lightweight fly wheel its probabbly best to just buy one. A lathe would work but the perfered way would be to blanchard grind it (a type of rotary surface grinder) untill the whole surface is cleaned up. (removing the dykem)

I can't see photobucket pictures, but if their are dowls, they would have to be pulled.

mustanghammer

iTrader: (3)

No way I would ever try to lighten a stock flywheel on anything, let alone a rotary. You can't take off enough meat to make a real difference without seriously compromising the safety of the flywheel. Not to mention the balance issue you would cause.

Saw pictures of a clutch failure on an stock port 12A FB racecar that occured at 7500RPM. Shrapnel went through the hood, heater core, fire wall, and destroyed the transmission case. Was most likely a pressure plate failure but it convinced me that you don't screw around with this stuff.

rxtasy3

iTrader: (2)

all machining lathes i've dealt with have both feeds.

now as for the 115 rpm speed, that's the chuck speed. the outside edge of the flywheel will actually be spinning faster than that. to more understand this, as a tire spins, the outer edge is turning faster than the center. so even at 115 rpm, if u catch ur knuckles on it, it's still going to hurt like a mf. the way i have considered turning a flywheel is to take an old eshaft and cut that end off and chuck that in the lathe. i think it can be done, but unless u know what ur doing i'd just leave it to those that do.

BlackWorksInc

I don't think that you can do it on a lathe easily, just too many variables. In all honesty a surface grinder would be better, but you'd still have to pull the dowel pins and figure out how to get the inside done properly. Also for your .016" I would look at the condition of the flywheel, if you have some chatter or burned spots you may want to go a tad deeper to try and remove that comprimised material, same as you would attempt on a cooked brake rotor.

But in the end its up to, I'd take it to get it properly done, but if you're sure that you have the right tools then go ahead.

Also something else, I might have missed it, but since you are replacing the flywheel you are going to be replacing the counter weight with the matching one as well right?

Banzai

iTrader: (13)

Bore a set of soft jaws or indicate it in and you could resurface it on a lathe. Of course it would have to be big enough (have at least a 9 inch swing). If any of this is puzzels you, you shouldn't attempt it on your own for the safety reasons mentioned in other posts. Yes the outer diameters are traveling faster than those at the center. It's expressed as SFPM, surface feet per minute. The amount of circumference distance which passes a stationary object (the cutting tool) at a given rpm. The smaller the diameter, the faster the rpm to maintain a constant SFPM rate.

Twilightoptics

iTrader: (1)

LOL Way too much work to save $30.

Not saying it cannot be done on a lathe, just way more time and setup. Flywheel surfacers are made for just that. Single bolt in the middle and a cone and you go.