Piano wire works in the cold weather wrapped around two wooden handles. You need a "helper" one outside ,one inside & 'saw" it back & forth!!!!

I've used the piano wire trick too. I also soaked the butyl with varsol to soften it up.

I think you should wait until i can go with you!

I always go from the inside with a Olfa knife.  Use lots of blades.

I'd do it

If you are woried about temp,  take a heat gun along,  that stuff will soften fast.

Rear glass is alot more forgiving than a windshield, but id still try it

as a winshield technitian, think i spelt that wrong, any way butyle is nasty stuff i always tried to cut this stuff when its cold, with the proper pull knife. the reason is that butyle resticks itself when its warm, a way to compensate for this is to do a section and then blow some talck into the cut. temperd glass is durable stuff unlike plate glass. what it does like is pinpoint stress like piano wire cutting into it i will shater not break. when you stick it back in use urathane but make sure to bloke it up until it hardens

Thanks to you as well. I hadn't thought about the resticking part. Very good point.

And yes, for sure it's not seeing butyl when it goes back in. I think I have a bunch of those little rubber blocks here too.

I've never shattered a glass cutting it out but I suspect it's been close because I've chipped a couple.

I just use a plazma cutter/ torch , and cut the whole back roof section...

  Then take it home, and warm up the glass later?

I find butyl a lot easier to cut than urathane,a lot of the time the stuff isn't stuck worth a hoot. I usually use a pull knife from the outside but an Olfa knife on the inside works well. Take someone with you to apply a little pressure to the inside of of the glass as you cut the glass from the butyl. If you don't have help use plastic windshield sticks or some sort of plastic wedges to hold the glass out a bit as you cut ( don't use anything metal or bye bye window ).

Good luck....

Carl,

Any chance of getting the donor car in a warm garage and let it sit a while before you try getting the glass out? Might make it easier...