Will this 8 1/4" work in place of my 7 1/4"?

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moparfreak77

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I have a 68 valiant slant six auto, wanting to put in my "new" 8 1/4" from a 73 dart. Will the parking brake bolt up fine? Do I need a new driveshaft?
 
Your parking brake should bolt on with no problems. You do not need a new drive shaft unless you go with big HP. Lengthwise you will have to get your driveshaft shortened by 1 1/4-1 1/2 inches.(To be on the safe side just measure from the middle of the forward joint to the middle of the back one.) I have had my old 6 cyl driveshaft behind my 360 with 350HP for over 7 years and it never said boo, just make sure you have the good U-joints and you should be good to go.
 
Ok, so by "new" I meant different length. What would a normal charge for getting that shortened? I have heard of ppl shortening the driveshafts themselves, how well does that work if you make sure the yoke is "clocked" right when you weld it?
 
What difference does it make how much it costs? You need to have it done. No way will we have that info, since we all live in different areas and cost is different everywhere.

"I" could get it done for probably around 100 bucks parts and labor. Your results may vary.

But then "I" would do it myself......as you eluded to.

All that's needed is a good straight cut. That's the key to it all right there. I have done probably a hundred through the years and got no vibration whatsoever.

I use my woodworking miter saw with a metal cutting blade. Works like a charm. Make sure the yokes are timed, like you said. I weld in 2 opposite places first. Then stop and make sure the yoke is good and still snug against the shaft. Then weld in two more 90* opposing points and finally finish all the way around welding about an inch at a time so as not to over heat the shaft.

I am sure there will be professionals who will scoff at the method, but it works.

At least it does for me.
 
"What difference does it make how much it costs? You need to have it done. No way will we have that info, since we all live in different areas and cost is different everywhere. "

It matters, do you like to know what something is going to cost before you do it? Maybe you don't, I do. I also realize the cost isn't fixed across the globe, but a ballpark guess is fine.
 
Just like Rusty said. Before whizz cutters I would take a hacksaw and cut the weld around the yoke just deep enough so I could knock it out. It has a nipple area that centers it inside the shaft that you want to leave intact. A level and very accurate measuring will get it done. Pay close attention to the orientation of both yokes on the shaft before you take it apart. Mark it, photograph it, remember it!
 
RustyRatRod said:
I am sure there will be professionals who will scoff at the method, but it works.

At least it does for me.
Click to expand...

The only thing pros do different is put it on a balance machine afterwards, but if it doesn't need it then it doesn't need it.

My OEM driveline had the yoke welded crooked so I had it removed, re welded and balanced. (100 bucks)
 
moparfreak77 said:
"What difference does it make how much it costs? You need to have it done. No way will we have that info, since we all live in different areas and cost is different everywhere. "

It matters, do you like to know what something is going to cost before you do it? Maybe you don't, I do. I also realize the cost isn't fixed across the globe, but a ballpark guess is fine.
Click to expand...

If I HAVE to have it done and cannot do it myself, no it does not matter how much. Since I have to have it done, it's GONNA get done.
 
My local top driveline shop here in Ottawa charged me $200 to shorten, balance and install new Ujoints (included).

Call your local driveline shops and get a quote

As was mentioned, it really doesn't matter the price as it's get it done or cant drive the car.... or stuff it in as is and wreck something. lol

If your near Ottawa... http://www.malmbergtruck.com/1427-michael-st/
 
I don't think there is a driveline shop within hours of me :( i'll have to do some asking around. What about the u joint size? Do the 8 1/4" and 7 1/4" use the same u joint?
 
Just as a note, if you've never cut and welded a driveshaft yourself. It can be interesting. Just watch the cropduster episode of roadkill to see potential results from said surgery if not done right.

There should be a drive-line shop near you. Most (around here anyway) transmission, and some auto service shops do drive shaft cutting/balancing/etc. Don't give up hope.
 
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