Track car flywheel choice

[sjw185]

Looking at fitting 0A3 gearbox on track car soon and was thinking about flywheels.
Car currently has 034 Aluminum flywheel which is around 4.5kg.
I suspect it maybe the culprit to a stalling issue I have and was thinking to fit a 7A this time round as I have one on the shelf.
If I was to go 7A is it worthwhile getting skimmed and lightened as I believe its heavier that 3b flywheel?
Any BTDT

Thanks
Steve

[k.alle]

Trim the casted bits sticking out on the back of the 7A flywheel, same side as timing pin.
Especially if you are using a standalone ECU to avoid trigger faults.

[sjw185]

Nice that should trim a bit of weight off as well, sounds like a good plan.

[sal_s2]

I have an o34 billet flywheel in my ur and it also occasionally stalls when slowing down/ braking to standstill. I have a 7a that I've sent to AndyP to get the timing pin welded on and some extra weight machined off
I was wondering whether the centre could be machined out so that it become like an rr flywheel, has anyone tried this as the needle bearing is in the crank on an ur

[sjw185]

I have an o34 billet flywheel in my ur and it also occasionally stalls when slowing down/ braking to standstill.

Stalling issue is a pain, went through changing ISV, throttle settings and checking vacuum booster trying to find an issue?
Then remembered I was using 7A flywheel before and suspected the flywheel.

[Error404]

I’ve machined a few 7A flywheels down, you can take a good chunk off the back which takes them down to the same as a 3B flywheel, which is a nice weight. You can also profile the perimeter around the clutch cover bolts to take a bit more off, but I wouldn’t want to take much more meat out of it really, it’s only cast iron at the end of the day. Also some thermal mass helps on a road driven car where the clutch is slipped

[AndyP]

What does a 3B flywheel weigh?

[Error404]

I have around 9kg in my head but it’s been ages since I weighed one

[sal_s2]

Alex, what do you reckon, can the middle be machined out to become an rr one in your expert opinion?

[Rusty]

Billet steel one? There have been a few over the years. 7-8kg and stronger than cast iron.

[Error404]

Alex, what do you reckon, can the middle be machined out to become an rr one in your expert opinion?

There is a big ring of material on the back (engine) side which you can machine off, but I don’t this it’s wise to reduce the thickness to less than that of an 3B / RR. Machine from
CrMo then the world is your oyster
As Andy says, 7-8Kg is the sweet spot for a fast road car with a road clutch you need to slip and nice manners

[Rusty]

Think mine's around 8.5kg machined from a 7A. Idle is a smidge lumpy and traffic isn't ideal but then the same could apply to the solid bushings, poly engine mounts and bucket seats...

If it's a pure track car, you could go alloy and get it all zero balanced.

[Error404]

Yours is most likely lumpy cos JNL “balanced” your bottom end

[Costash]

Alex is not helpful isn't it .Lol
I feel sorry for everyone spending loads of money on engines and be done for it .