Has anyone cut big bits off an alloy frame before?

**koba** · 7th March 2011, 18:54

Has anyone cut big bits off an alloy frame before?

Has anyone cut the front engine mounts off an NSR before?

I'm thinking about doing this at some stage, there is plenty to do before I get this far but I was pondering whether it is a good idea or not.

I would probably cut through the cast part of the front down bits that the NSR engine was once rubber mounted to.

I know some castings can release internal stresses when cut and crack but I'm not sure if I need to worry about that or not. Also I don't know what I will find inside so I may drill a few little holes to feel it out first.

Anybody have experience with this they would care to share?

**Grumph** · 7th March 2011, 19:02

If the frame originally used the engine as a stressed member, you may finish up with something pretty limp...
A well known example was Tony Mcmurdo putting a Kawa twin into a VFR honda frame. Without the V4 bracing it, it wanted to walk around on turn in....he welded a full length reinforcement on top of the side rails which stiffened them up just enough.

**Gigglebutton** · 7th March 2011, 19:08

I have welded up loads of ali frame part when cracked or after crashes with no problems. We have had no problems welding any ali on bikes but it does soften the higher tensile ali. If you anneal it before cutting it will lesson any chance of cracking.

**koba** · 8th March 2011, 06:28

Originally Posted by Grumph

If the frame originally used the engine as a stressed member, you may finish up with something pretty limp...
A well known example was Tony Mcmurdo putting a Kawa twin into a VFR honda frame. Without the V4 bracing it, it wanted to walk around on turn in....he welded a full length reinforcement on top of the side rails which stiffened them up just enough.

That sounds scary...

The bits I'm cutting off are all good in that respect, while they may have had some contribution to overall stiffness they have been flapping in the breeze the whole time the thing has been a bucket and I don't notice any ill effect. The main Beams are nice and chunky.

Cheers for the warning.

Originally Posted by Gigglebutton

I have welded up loads of ali frame part when cracked or after crashes with no problems. We have had no problems welding any ali on bikes but it does soften the higher tensile ali. If you anneal it before cutting it will lesson any chance of cracking.

Cheers, I will have a look into this...

**Hawkeye** · 8th March 2011, 06:44

Had to read that title a second time.

I thought it said 'tits' - ah well - ho hum

**Henk** · 8th March 2011, 16:37

Originally Posted by koba

That sounds scary...

The bits I'm cutting off are all good in that respect, while they may have had some contribution to overall stiffness they have been flapping in the breeze the whole time the thing has been a bucket and I don't notice any ill effect. The main Beams are nice and chunky.

Having read that I'd be breaking out the hacksaw, but then I'm a bit on the rough side when it comes to this sort of thing.

**koba** · 8th March 2011, 18:26

Originally Posted by Hawkeye

Had to read that title a second time.

I thought it said 'tits' - ah well - ho hum

So did I for a moment and I bloody typed the thing!

Men!

Originally Posted by Henk

Having read that I'd be breaking out the hacksaw, but then I'm a bit on the rough side when it comes to this sort of thing.

I would have too but have seen a sawn off bellhousing recently that didn't cope with it. I think I'm being a pussy tho and should just hack the feckers off.