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Where to cut and weld V8 driveshaft


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Guys,

I am working on getting the driveshaft make for my LS1 conversion. I have the clutch LSD and I am using the 300ZXT flange and driveshaft. I was wondering where is the ideal place to cut the driveshaft and weld it to the GM driveshaft? In other words where do I put the welding joint? in the middle, forward or rear etc.. and what are the reasons behind it? Thanks for the info.

Vinh

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Well it all depends, Do you have BOTH drive shafts? All I can say for sure DON"T do it in the middle. And use the larger diamemeter of the two. I had a new drive shaft made with new parts and it cost me $350. I've heard members here getting driveshafts modified for as little as $200. Last thing, how are you going to balance it if you do the welding yourself? I would just take it the driveline shop and have it done. Just my opinion.:mrgreen:

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I can tell you from experience that for your application you don't want to do that unless your experienced at it. I've done both automotive and truck driveshafts but I wouldn't even consider doing one for the z or any race car for that matter, too much at stake! They are relatively easy to do provided you have the right tube size and the correct yokes, flanges, etc. Balancing is a must for high rpm vehicles like cars. Big trucks rarely see over 2300 rpm at the drive shaft and don't need it although it makes a truck alot smoother to drive.

 

If you do it yourself you'll need a pipe cutter to get the tube straight or use a lathe. Once you cut the tube you place one flange in the end of the tube, they have a machined weld joint. If your using an old flange, have it remachined as it makes it alot easier. you have to get it square or it's junk, this is the hard part. They press fit slightly into the tube so you tap on it with a hammer to get it true. Several ways of doing it, by bottom of the ujoint cup works about the best for me. Tack weld it on opposite sides and double check it for square, tack it again so you have 4 sides done and check it again, then weld it all around with a mig. Same for other end, measure bottom of ujoint cup to ujoint cup and make sure that they are phased correctly otherwise the ujoints won't last a week. Send it off to get balanced.

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Sorry for the misleading info. I wasn't doing this myself. I have both driveshafts and will bring them both to the driveshaft place. I was just wondering where is the ideal place to cut and mate both DS. I did a search and found some info about the 1/2 critical speed balancing so I will make sure I will ask the driveshaft shop about it.

 

Again I have no idea where the driveshaft shop will cut both driveshafts and weld them together. That's why I asked here so that I make sure to mention where they should cut and mate the shafts together if they don't know better. Thanks for the info guys.

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They SHOULD shorten the Chevy unit, and either use a conversion U-joint for the 300ZX flange, or you can buy the 300Zx flange from JTR, either way would work fine.

 

I had the Chevy driveshaft shortened and balanced for mine at a large truck (tractor rig) place locally. $65 to shorten and balance, about another 35 for 2 new Spicer u-joints installed.

 

I've used them quite a few times and never had any issues.

 

Might look around your area for a large truck repair facility...

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