B20 lightened flywheel - for a DD

AndrewNance · 02-10-2013, 11:48 AM

How light is too light for a daily driver?

JERIC · 02-10-2013, 05:21 PM

Idk for a b20, but my 2.0 Porsche 914 has an 11lbs flywheel in it and drives great, once used to it, I want a lite flywheel for my 142 but don't have cash for that yet, my m41 is on its way out and am gathering parts for a t5 swap (tranny easy part)
JERIC

740tankDriver · 02-10-2013, 05:25 PM

15 pounds is probably just right. you want just enough energy storage for comfort. remember that the disc and plate is also part of that assembly and net mass.

AndrewNance · 02-10-2013, 06:11 PM

I will take these things into consideration. Thanks guys.

gsellstr · 02-10-2013, 09:08 PM

I have a 17lb one on mine, love it, could probably go down a couple more pounds but that's it for a daily. sure beats the 24.5lb stock flywheel.

towerymt · 02-11-2013, 02:42 AM

~16lb was excellent on my b23. 9-10lb of the aluminum one I have now I feel is too light. the flat b21 flywheel started off at ~20-21lb and was thinned out to around 16lb as I recall.

John V, outside agitator · 02-11-2013, 03:30 AM

Quote:

Originally Posted by AndrewNance

I will take these things into consideration. Thanks guys.

Does anybody know what the bolt circle is and bolt size?

Steel at around 14 lbs could be done pretty easily when one has blanks and other dimensions set.

gsellstr · 02-11-2013, 12:13 PM

Depends on what motor he has John. The 8-bolt B20's run the standard B21/23/230 pattern. Not sure on the 6-bolt stuff.

John V, outside agitator · 02-11-2013, 01:05 PM

Quote:

Originally Posted by gsellstr

Depends on what motor he has John. The 8-bolt B20's run the standard B21/23/230 pattern. Not sure on the 6-bolt stuff.

Yeah that's why I was asking, like is it same bolt, same bolt circle just 6 vs 8?
Same register on the back?

Redwood Chair · 02-11-2013, 01:12 PM

We're not much for hard numbers around here, but I suppose I could mosey downstairs with a verynear brake caliper and grab some approximate numbers.

AndrewNance · 02-11-2013, 01:13 PM

It is an 8-bolt flywheel. Probably should have mentioned that in the OP. I have heard a lightened flywheel is a great bang for your buck and a great way to please the butt-dyno with 40 extra faux HP.

grnmachine02 · 02-11-2013, 01:28 PM

Quote:

Originally Posted by AndrewNance

It is an 8-bolt flywheel. Probably should have mentioned that in the OP. I have heard a lightened flywheel is a great bang for your buck and a great way to please the butt-dyno with 40 extra faux HP.

Also it depends on what kind of driving you're doing. Lots of stop and go traffic could make a difference in DD quality. When I still had my GSR swapped CRX ( say what you want vtac, and fwd, that thing was fun as hell) I had a very light flywheel in it and it was a bitch in traffic.

Redwood Chair · 02-11-2013, 01:30 PM

The guys at the machine shop were comfortable removing 4lbs on the 6bolt flywheel I took them.

Redwood Chair · 02-11-2013, 01:32 PM

Quote:

Originally Posted by grnmachine02

Also it depends on what kind of driving you're doing. Lots of stop and go traffic could make a difference in DD quality. When I still had my GSR swapped CRX ( say what you want vtac, and fwd, that thing was fun as hell) I had a very light flywheel in it and it was a bitch in traffic.

^ This.

I know I'm going to be branded a pariah for saying it, but I like the lighter clutch pedal and heavier dog dish flywheel for what I do with the car.

gsellstr · 02-11-2013, 02:23 PM

I was dd'ing mine in stop and go rush hour for quite a few years with the lighter flywheel, never bothered me actually. It's actually still able to recover, perhaps a little easier from a near-stall than with the heavier flywheel, still has easily enough grunt to keep things going. I'm actually quite happy with the weight, both for dd'ing and for beating the piss outa it. The shop I took it to had no real concerns with pulling 7.5lbs from it. Only thing is he said never bring another one of those back...he killed 3 cutter bits on it, damn thing was so hard. He's used to American stuff, not old Swedish iron.

AndrewNance · 02-11-2013, 02:26 PM

I might just take it over there and ask them about removing 5 pounds. If they seem sketched out then I'll go from there.

John V, outside agitator · 02-11-2013, 02:59 PM

Quote:

Originally Posted by gsellstr

I was dd'ing mine in stop and go rush hour for quite a few years with the lighter flywheel, never bothered me actually. It's actually still able to recover, perhaps a little easier from a near-stall than with the heavier flywheel, still has easily enough grunt to keep things going. I'm actually quite happy with the weight, both for dd'ing and for beating the piss outa it. The shop I took it to had no real concerns with pulling 7.5lbs from it. Only thing is he said never bring another one of those back...he killed 3 cutter bits on it, damn thing was so hard. He's used to American stuff, not old Swedish iron.

Those damn things have become half ceramic with all the millions of heat cycles..

And almost nobody is used to machining cast iron anymore....it ain't hi-tech enough.

gsellstr · 02-11-2013, 03:25 PM

This shop is well versed in iron stuff, hell, even YOU may have heard of em....Rex Hutchinson (been around since before your rally days

).

Not many shops in town that could both lighten AND balance a flywheel. Many could do one or the other, not both, he was able to do both, and that was around 10 years ago.

blitzwagen · 02-12-2013, 07:58 AM

A stock flywheel is about 24 pounds and the consensus on the p1800 group is that 20 pounds is safe.

Here's what Phil Singer has to say about where the material should be removed :

"You need to be conservative for safety reasons, and some shops don't
want to lighten them because of liability concerns. Having a flywheel
come apart is seriously dangerous to your health.

My machinist usually takes off 1/4" depth of the rim on the clutch side,
going about 1/2" in from the ring gear. On the block side, you can taper
the thick outer section somewhat. The overall thickness is unchanged,
other than what's taken off as a normal part of resurfacing. Of course
you need to rebalance it once that's done.

It's only a few pounds lighter, but all the weight comes off the outer
edge where it does the most good."

7mgtesup · 02-12-2013, 09:06 AM

I found putting the TTV flywheel on my 940 turbo actually improved its on road manners. The total mass including the clutch dropped from 24kg (53lbs) to 17kg (37.5lbs) thats 15.5lbs all the stuff people said would happen hasn't. If anything I would like less mass and centre it all better with a 7" clutch and get that weight down even more.

Canuck · 02-12-2013, 11:30 AM

I had 6 lbs taken off the stock flat flywheel. No problem...

I've since decided to do the TTV steel piece (they will do either 6 bolt or 8 bolt).

With clutchnet clutch to drive the T5.

I haven't driven the new set-up...car is a little "apart" right now. The TTV is around 11/12 lbs and I don't foresee any issues.

02-10-2013, 11:48 AM	#1
AndrewNance Amateur hour! Join Date: Oct 2011 Location: Winston-Salem, NC	B20 lightened flywheel - for a DD How light is too light for a daily driver? __________________ '67 122 - b230, t5, 8.8 Feedback

02-10-2013, 05:25 PM	#3
740tankDriver Post-Hypnotic Sigma Join Date: Aug 2006 Location: Under your nose.	15 pounds is probably just right. you want just enough energy storage for comfort. remember that the disc and plate is also part of that assembly and net mass. __________________ Happy Passover! Great Victory!

02-10-2013, 09:08 PM	#5
gsellstr Vintage anti-ricer Join Date: Oct 2004 Location: Somewhere in a northern California smog bank	I have a 17lb one on mine, love it, could probably go down a couple more pounds but that's it for a daily. sure beats the 24.5lb stock flywheel. __________________ RIP Doug Williams "Mr. Doug" 4/15/2009 Pete Fluitman "fivehundred" 7/14/2013 Mick Starkey "TrickMick" 1/10/14 Mark Baldwin "blue850t5" 7/19/18 Nick Fengler "fengler" 8/6/18 Thomas Fritz "stealthfti" 10/11/18 Bob Davi "bob davi" 10/2021 74 144 B20 http://forums.turbobricks.com/showthread.php?t=224983 90 745Ti http://forums.turbobricks.com/showthread.php?t=334698 If you need Superpro bushings PM me for price and availability!

02-12-2013, 09:06 AM	#20
7mgtesup Board Member Join Date: Apr 2011 Location: Norfolk, England	I found putting the TTV flywheel on my 940 turbo actually improved its on road manners. The total mass including the clutch dropped from 24kg (53lbs) to 17kg (37.5lbs) thats 15.5lbs all the stuff people said would happen hasn't. If anything I would like less mass and centre it all better with a 7" clutch and get that weight down even more. __________________ Turbo lag is the moment the car next to you thinks he's going to win.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

02-10-2013, 05:21 PM	#2
JERIC Board Member Join Date: Sep 2007 Location: SOUTH JERSEY	Idk for a b20, but my 2.0 Porsche 914 has an 11lbs flywheel in it and drives great, once used to it, I want a lite flywheel for my 142 but don't have cash for that yet, my m41 is on its way out and am gathering parts for a t5 swap (tranny easy part) JERIC

02-10-2013, 06:11 PM	#4
AndrewNance Amateur hour! Join Date: Oct 2011 Location: Winston-Salem, NC	I will take these things into consideration. Thanks guys.

02-11-2013, 02:42 AM	#6
towerymt the real Towery Join Date: Sep 2002 Location: VA, USA	~16lb was excellent on my b23. 9-10lb of the aluminum one I have now I feel is too light. the flat b21 flywheel started off at ~20-21lb and was thinned out to around 16lb as I recall.

02-11-2013, 12:13 PM	#8
gsellstr Vintage anti-ricer Join Date: Oct 2004 Location: Somewhere in a northern California smog bank	Depends on what motor he has John. The 8-bolt B20's run the standard B21/23/230 pattern. Not sure on the 6-bolt stuff.

02-11-2013, 01:13 PM	#11
AndrewNance Amateur hour! Join Date: Oct 2011 Location: Winston-Salem, NC	It is an 8-bolt flywheel. Probably should have mentioned that in the OP. I have heard a lightened flywheel is a great bang for your buck and a great way to please the butt-dyno with 40 extra faux HP.

02-11-2013, 01:30 PM	#13
Redwood Chair - Stock PSI Or Bust - Join Date: Mar 2007 Location: Ocean Beach S.F.	The guys at the machine shop were comfortable removing 4lbs on the 6bolt flywheel I took them.

02-11-2013, 02:23 PM	#15
gsellstr Vintage anti-ricer Join Date: Oct 2004 Location: Somewhere in a northern California smog bank	I was dd'ing mine in stop and go rush hour for quite a few years with the lighter flywheel, never bothered me actually. It's actually still able to recover, perhaps a little easier from a near-stall than with the heavier flywheel, still has easily enough grunt to keep things going. I'm actually quite happy with the weight, both for dd'ing and for beating the piss outa it. The shop I took it to had no real concerns with pulling 7.5lbs from it. Only thing is he said never bring another one of those back...he killed 3 cutter bits on it, damn thing was so hard. He's used to American stuff, not old Swedish iron.

02-11-2013, 02:26 PM	#16
AndrewNance Amateur hour! Join Date: Oct 2011 Location: Winston-Salem, NC	I might just take it over there and ask them about removing 5 pounds. If they seem sketched out then I'll go from there.

02-11-2013, 03:25 PM	#18
gsellstr Vintage anti-ricer Join Date: Oct 2004 Location: Somewhere in a northern California smog bank	This shop is well versed in iron stuff, hell, even YOU may have heard of em....Rex Hutchinson (been around since before your rally days ). Not many shops in town that could both lighten AND balance a flywheel. Many could do one or the other, not both, he was able to do both, and that was around 10 years ago.

02-12-2013, 07:58 AM	#19
blitzwagen Board Member Join Date: Feb 2009	A stock flywheel is about 24 pounds and the consensus on the p1800 group is that 20 pounds is safe. Here's what Phil Singer has to say about where the material should be removed : "You need to be conservative for safety reasons, and some shops don't want to lighten them because of liability concerns. Having a flywheel come apart is seriously dangerous to your health. My machinist usually takes off 1/4" depth of the rim on the clutch side, going about 1/2" in from the ring gear. On the block side, you can taper the thick outer section somewhat. The overall thickness is unchanged, other than what's taken off as a normal part of resurfacing. Of course you need to rebalance it once that's done. It's only a few pounds lighter, but all the weight comes off the outer edge where it does the most good."

02-12-2013, 11:30 AM	#21
Canuck Frozen Garage Hell Join Date: Feb 2006 Location: Lethbridge, AB, Canada	I had 6 lbs taken off the stock flat flywheel. No problem... I've since decided to do the TTV steel piece (they will do either 6 bolt or 8 bolt). With clutchnet clutch to drive the T5. I haven't driven the new set-up...car is a little "apart" right now. The TTV is around 11/12 lbs and I don't foresee any issues.