lightened/stock flywheel compatibility

[jardyDB]

hhhhhhhhhhhhhhi

ive got a B3 in my 121, clutch needs doing soon and since its a DD im planning on getting clutch, flywheel, rear main, shaft seals etc all at once so i can do it in a night

id have to get flywheel machined which is inconvenient so nows a good time to upgrade to something lighter

the trouble is there isnt much for B3's over here, so what other B series flywheels fit the B3's starter/5spd? B5, B6? differences between DOHC or all same?

ive searched and found FMS, another quick search and all i get are part numbers but no catalogue to reference them. anyone have the relevant part number for one of theirs? if they still make em i dunno

fidanza do for the B6 i think, but i dunno if its cool with the B3

[FestYboy]

you must use the flywheel that goes with the transmission.... any B series engine will accept E F and G series trans and flywheel. so if you kept your stock trans and swapped a BP engine, the BP would HAVE to use an E series flywheel, NOT the BP flywheel. alternately, if you mated a B6-DE to a Laser, you'd have to use the G series flywheel from the laser, NOT the F series flywheel from the donor B6-DE.

take your stock flywheel and have it surfaced, then have them remove 1.5 kilo from the BACK of the flywheel, then balance it.

[rmoltis]

I personally wouldn't lighten my flywheel. First off inline 4 cylinder engines have bad mechanical balance and the weight of the flywheel helps keep engine operation smooth. As well as the flywheel is also used to store energy while driving to help keep engine rotating. Say your driving on flat road. then you come up to a hill. The stored energy helps sustain engine rotation and speed to help you get up the hill better without slowing down as much. So it helps give you better mpgs and sustain speed and rpms. It is actually quite useful for what is was designed for stock.

But if you want to lighten it do what dude said and remove material from the backside and make sure they don't touch the outer weight ring so it still helps retain inertia based on the leverage point from the outer circle of the flywheel. And it will still be decent to drive from day to day.

[jardyDB]

nice, thanks for that

im familiar with the mechanics of it and not overly keen to lighten the stock flywheel. im sure its worked for many but im not comfortable with the principle, id rather get one aftermarket - made for that specific purpose

the trans i have is tiny tiny, starter at the top, looks like this:



i cant find much info on trans, doubt its G, probably not F, guessing its an E trans?

[blkfordsedan]

If its the stock trans behind the B3 then it's an E series. The B3 flywheel you have is the smallest anyway. The FMS ones were just factory ones turned down like FesYboy said.

[standard235]

I went from a 18lb flywheel to 9lbs on my Talon with a clutchmasters fx400 unsprung 6 puck... I think a few pounds off this boat anchor wheel will be fine

[Festy46]

I was researching light weight flywheels several years ago and found these guys. If you got the money, they will make you a flywheel. IIRC, you had to send them an old stock flywheel for them to use as a pattern to get all the dimensions right.

http://www.10000rpm.com/index.php

[bobbyspider]

I lightened my stock flywheel. Don't remember the final weight though sorry

[jardyDB]

ah i see, so noone really keeps a stock

fair enough ill stick with oem

for the record, exedy dont make em either. they make a button clutch kit for this trans though haha

[blkfordsedan]

If you were to do an engine swap and planned on driving it hard, you would probably want to upgrade to an F or G series trans anyway. Then you may be able to find an aftermarket aluminum flywheel that's readily available. Many members on here have had their stock B3 flywheel lightened. I don't remember ever hearing of any issues, and most report a noticeable difference.

[Festy46]

We have used a local machine shop lightened one and also one from FMS. Both were run over 7,000 rpms with no problems. The best light flywheel performance seemed to be in the B6-ME. It may have just been the distinctive 16 valve sound, but it sounded like somebody dumped the throttle on a sprint car in the pits doing a tune up when you punched the throttle in the B6-ME with a carb.