m42 JB racing Lightweight Flywheel

[redcarbon]

I'm not sure if I've seen a post on here about it, but I just got the JB racing flywheel installed in my 318is so I thought I'd share my thoughts so far.

I just got it installed last night, I haven't driven it too much but the whole car seems lighter and easier to rev in the lower gears. There are a few extra vibrations now off throttle, but nothing unbearable.

Revving in neutral is a bit quicker than it was before but rev matching while down shifting is much quicker. And the car shuts off more quickly and starts up quicker. Transitions on throttle are much quicker, it gets going very well.

I was expecting to have a hard time starting it from a standstill but it's not much different than stock. I have not tried starting it up a hill so we'll see. It doesn't like to hang in gear around 1000 rpm as well as it used to but that is to be expected. Traffic this morning wasn't unbearable but takes a bit different driving style.

It's a nice upgrade, I needed a new clutch anyway so it was a good time to do it. I'll do some harder driving later this week and let you know. I also have an autocross this weekend.

[Rob]

Price?


please post a followup after you have some more time with it. From this post, it doesn't sound like nearly the upgrade that it looks like on paper.

[nickmp0wer]

any thing else to say?

[gazellebeigem3]

i did the single mass 325i conversion, it was free, probly wouldnt pay much more than that.

[redcarbon]

I have driven it some more and my review hasn't really changed. It's not as drastic of a change as I was expecting, but definitely better. The flywheel seems not to eb the only overweight rotating part in the M42.

It's most likely not worth the $600 I paid from Bimmerworld, but I plan on staying with the M42 for as long as it'll go so I thought I'd do all I can to get the most out of it.

I like it, revs quicker, definitely quicker when you get on throttle, just overall nicer to drive. It likes to rev in the upper rpms even more. Between 6 and 7,000 rpms the M42 sounds really nice, like where the engine was designed to run. I'm glad I did it and, if you have the tranny and clutch off and have $600 to blow, go for it.

[john318isau]

gazellebeigem3 -- did you notice much difference after the 325i flywheel conversion?

Has anyone done the M40 single mass flywheel conversion?

[robweenerpi]

I have one in my spec E30 car. Car isn't running yet, so no comparison and it's not much lighter. I can get these for about 300 bucks and I'm sure you could have it machined down to much lighter. Also, you have to use a different and hard to get clutch kit.

[nickmp0wer]

are you doing spec e30 with a m42?

[robweenerpi]

Sure am and will probably be the only one. It will probably be REALLY tough for me to pass though. It'll be fun but i'm not sure how well the car will do. I think it should be about as fast as a 6 but it's tougher to beat cars with more power.

[john318isau]

I just fitted a M40 flywheel a few weeks ago. Saves about 6 lbs. Seems a little more responsive and makes gear changes a little faster. Not a huge difference though. There is a noticable increase in vibration when accelerating at very low speeds in a gear too high. Only cost $100 AUS so a cheap worthwhile modification if you have to change your clutch anyway as I did.

[Snowmann]

are the 4's allowed to weigh less in spec e30? the m42 isn't that far off pace with a m20 in race form... however racing e36's in an m42 e30 is pretty much a setup for failure...

[permit]

Must be just the M42s that these flywheels don't make a huge upgrade on, because my JBR flywheel completely changes the way the car drives. It's just disgusting how easily you can blip the throttle during downshifts, I love mine and is very much worth the cash.

[fiftytakedowns]

Sorry for digging up old thread, but do you know if there is a Rivet to lock the flywheel at TDC?