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To lighten or not flywheel

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Windrideror Avatar
Windrideror Carl Rosenburg
Redmond, OR, USA   USA
Ok so going to pull the flywheel off of the engine and send out to have machined to except the Datsun pressure plate and clutch. This is being done in prep for putting in the Datsun 5spd transmission with Gerards install kit. Question is should I have it lightened while having the other machine work preformed or just leave it as it is. Engine is not really going to be anything radical. Maniflow header to 1 1/2" exhaust to a Harley Sportster muffler. Going to rebuild the SU carbs and reinstall them losing the Weber DCOE carb that was on it. I'm installing a Swiftune SW5-07 cam while engine and transmission are out of the car as well as a set of 1.5 forged rockers. So what are the pros and cons of taking some weight off of the flywheel? I'm thinking of maybe losing 4 lbs. Enough to let it spin up quicker but not so much as to cause issues with take off from a stop. Any input would be helpful.

Thanks Carl

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ice Avatar
ice Gold Member Larry Ice
Lawrenceville, GA, USA   USA
CArl, not too long ago flywheel lightening was a topic of discussion. You might look it up in the library. But...since you asked, a couple of years ago I had my 1275 engine rebuilt to OEM specs and while I was at it had the flywheel lightened by 4 lbs. I have noticed no ill side effects from doing that. A bit later I installed a Datsun 5spd using a Rivergate kit and have had no side effects with that transmission and flywheel assy either. I do keep the rpm's at idle 1000 and 1100 though. The reason I did that is as you mentioned about take off with street driving.



Iceman

Atlanta GA

60 AH MK1
62 AH MKII
67 Midget
71 Midget

halloween Gregg B
Sheridan, WY, USA   USA
I did what you're planning about 20 yrs.ago. My flywheel machinist lightened my flywheel as much as he could safely, and I didn't have any downside effects at all, but I can't tell you how much it helped because of the motor modifications I also made. It was a street car.
GB

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Windrideror Avatar
Windrideror Carl Rosenburg
Redmond, OR, USA   USA
Larry, Greg Thanks for the replies. Think that while it is out and in the shop I will go ahead and have some weight taken off. The new clutch and pressure plate will weigh more than what the stock units did so it may end up being equal in the long run. I am using this car as a summer time road car. Just a fun little car to play around with. Not looking for it to be a race car and I want it to remain well mannered for road use.

200mph Avatar
200mph Platinum Member Mike Joy
Winston-Salem, NC, USA   USA
DO IT! Anytime you reduce rotating mass you free up available power and torque for better acceleration.



"Have you ever thought... Everyone driving slower than your MG is a MORON, everyone driving faster must be a FREAKING IDIOT!". . . George Carlin

Cruisedon66 Avatar
Cruisedon66 Pete W
St. Louis, MO, USA   USA
1976 MG MGB
If you haven't seen this thread. It might offer some tips on Rivergate conversion.
http://www.mgexp.com/phorum/read.php?1,2201944

ice Avatar
ice Gold Member Larry Ice
Lawrenceville, GA, USA   USA
Carl, just a thought, I would have the flywheel balanced by itself. If you balance both the clutch assy and the flywheel together and you need to change the clutch, both it and the flywheel will have to be balanced together again. That means removing the flywheel from the crank. For the most part the clutch assy's are balanced well enough for a street car.



Iceman

Atlanta GA

60 AH MK1
62 AH MKII
67 Midget
71 Midget

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halloween Gregg B
Sheridan, WY, USA   USA
What I asked for and what I got may not be the same, but I asked for my flywheel to be balanced separately, then the clutch bolted on and rebalanced without changing the already balanced flywheel.

S1 Elan Kurt. Appley
Akron, Ia., USA   USA
In these parts I have not found a shop that will balance the flywheel separate from the crank. They also want to balance the whole assembly if possible.

Kurt.

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halloween Gregg B
Sheridan, WY, USA   USA
Keep looking??

ice Avatar
ice Gold Member Larry Ice
Lawrenceville, GA, USA   USA
Kurt, my bad, you are right. When I did the balancing it was a package deal for all parts in the engine, not just the flywheel alone. The clutch apparatus was not balanced since I expect to need a clutch plate before rebuilding the engine. I have replaced numerous clutch assys and not had a problem with them being unbalanced.



Iceman

Atlanta GA

60 AH MK1
62 AH MKII
67 Midget
71 Midget

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