If you mean the outer ring, that's the lip that centers the IP on the flywheel -- later cars use pins for locating the IP. If you mean the groove in the flat surface I think that is there so that as the flywheel surface wears, it doesn't wear a pocket in the surface of the flywheel that will cause problems later if you swap in a new disc without resurfacing.

 

Blanchard grinding is to rotary surface grinding as Kleenex is to tissue paper.

 

Thanks

 

Actually a better analogy would be:

Blanchard grinding is to rotary surface grinding as Xeroxing is the photocopying.

 

So "Blanchard" is the machine thats used to do the rotary surface grinding?

i assume this is something like a decking machine or a planer or something, can you do this type of surfacing on the outer brake disc, the side which has the hub?

 

Can a flywheel be welded and then re-surfaced, safely? That could take care of surface cracks.

 

No. The temptation would be to metal-spray the surface and regrind, but the thermal stresses endured in normal use would strip off the new metal. Buy a good used one if the surface cracks don't grind out. It takes some serious surface cracking to get beyond the grinder's capabi;ities. If you have a doubt about it, let the machinist give you a specific opinion about the part that you have.

 

I don't have a manual trasnmision, but damn! this thread was great........

 

The machine is very similar to the grinding/decking/surfacing machine used for steel cylinder heads, but adds the ability to rotate the flywheel during the surfacing process. Heads are generally done in one direction, passing over the rotating grinding head.

Grinding brake rotors is a little more complex. Two rotary grinders are used, one set up on each side of the rotor. The grinding heads are maintained parallel as the rotor is slowly turned between them. It's a bit more complex than setting up a double single-cut on a disk lathe. And costs more. In many places, it's cheaper/better to just replace worn holed/slotted/relieved rotors even if they are still thick enough.

I will probably get holed rotors when I replace just because they look cool. Originals will come off with about 100k on them, and it's not real likely that I will live long enough to go through another set.

 

also dont forget that for every bit of material removed from a flywheel, the less clamping force the pressure plate will have.
Yes, dump the cracked flywheel and get a good used one or new one.

 

+1 I tried that years ago on an old drag car with alot of abuse given to it and destroyed the new disk in the process.If it's gone,say goodbye and get another. Ed.

 

Mark, that makes no sense at all. Care to elaborate?

 

Nevermind. I forgot that the mounting hole surface for the pressure plate would be machined as well. if you machine the pressure plate surface, then that could be an issue. (reduced clamping forces)

sorry

mk

 

DAMMIT KIBORT LOL

 

Paul, there's gotta be a brazillion places near london that will do this properly. i hear there are 1 or 2 manual transmission motor cars on your island.