Cant Install Flywheel - Crank Too Big?

[jaik]

Hi Guys,

Im trying to install an Xtreme Lightweight flywheel on my RB20DET A31 and I cannot seem to get the flywheel on! Ive done some quick measurements and the Outside of the crank is about 36mm and the internal diametre of the flywheel is about 35.25-35.50mm - the factory flywheel is about the same as the Xtreme. Im using those caliper thingies and they definately have to extend after measuring the flywheel to fit over the crank.

Am I missing something here or is the fly too small to fit over the crank? I know it should be tight but is there a trick I can use? Ive tried sitting the flywheel just over the crank and hitting a piece of wood on the flywheel to get an even fit but it wont budge. Ive also tried a little lubrication but to no avail.

I had thought about installing all 6 flybolts and tightening them evenly to get it to "press over" the crank but If its not gunna go then I can see me crossthreading something and I would hate for that to happen!

Thanks!

JK

[Scotsman]

Couple of options from one backyard mechanic to another.

1. Put your flywheel on your BBQ on low heat for 10min, then with some heavy duty gloves try to install quickly. The heat should grow the flywheel by just enough. I have done this before when shifting ring gear (the bit the starter turns) from one flywheel to another and it works a treat. I know it sounds a bit redneck, but this should work. Alternative is an oxy torch to heat it up, but can be hard to get an even heat with an oxy.

2. The press method with the flywheel botls 1/2 turn at a time should work. Just take it easy.

I'd say heating it would be the way to go thou. Hope that helps.

[GTRgeoff]

But it has to come off some time Chris so I don't recommend it. Talk to the supplier and check the dimensions, my suggesdtion is it didn't get checked at manufacture. It shouldn't be an interference fit but a sliding fit. A machine shop or engine builder should be able to quickly take it out to the right dimension

[jaik]

I have been contemplating getting 40tho taken off from the inside of the flywheel - BUT i tried to get the factory flywheel back on today and it wont go back on either... how bizzare.

My crank has grown haha

JK

[jaik]

I also noticed that the factory flywheel has some extra machining done on the inside whereas the xtreme doesnt.

So it should be safe to take material off the inside of the flywheel? It should still bolt up OK and should still be "hub centric" over the crank but it wont be tight as buggery like it is now.

JK

[dezzabye123]

if it is the alum one i just left mine in the sun for 30min and it went straight on. to get it back off u just heat it back up.. easy!!

alum expands at diff rates to steel so i wouldnt machine it

[jaik]

I got the Chrome Moly one.

Im going to ring Xtreme now to pick their brains about it

JK

[Scotsman]

if it is the alum one i just left mine in the sun for 30min and it went straight on. to get it back off u just heat it back up.. easy!!

alum expands at diff rates to steel so i wouldnt machine it

hmm I dunno if i'd go machineing it, unless you can confirm your crank is actually bigger than stock. Plus it will be under heat cycles because of the fact it is a friction surface item.

Let's say you take a bit out of it, then it will fit on nicely while cold. But the flywheel expands at a different heat rate to the crank... I dunno perhaps then it may not run 100% true. Just chuck it on the Bar-by and cook yourself up a flywheel with sauce, slide it on and bolt it up. I'd go for tight fit anyday!! (no sexual inuendo intended of course)

[jaik]

I called Xtreme and they recommended heating it aswell. I will give that a go before looking at machining it. I'll have to use the gas stove top inside to do it (whilst the missus is out haha)

JK