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Old 11-29-2012, 11:40 AM   #1
mikeindustries
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Default Calling all SOA conversion guys......

I am getting ready to do a SOA conversion to my 1976 Scout II with a reverse shackles in the front. The Scout has the stock 304, 727tf, and Dana 20 drivetrain. My question is: when you did the SOA on the rear did you need to modify the drive shaft? I will be adding 5" shackles in the rear so I'm not sure what's gonna be required.

I know I will need a new shaft in the front. Gonna also add 5" shackles. Think I'm gonna go with a cv drive shaft up front. Your thoughts?
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Old 11-29-2012, 11:51 AM   #2
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Default Re: Calling all SOA conversion guys......

There really is no hard fast rule here, but the answer is usually yes. The rear driveline tends to be too short after a spring over.

For the front a cv is usually not needed unless you're planning on doing a lot of 4xhigh travel. What you need to insure is that you are getting a long travel front drive shaft to work in conjunction with the r/s.
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Old 11-29-2012, 09:08 PM   #3
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Default Re: Calling all SOA conversion guys......

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Originally Posted by ihpartschad View Post
there really is no hard fast rule here, but the answer is usually yes. The rear driveline tends to be too short after a spring over.

For the front a cv is usually not needed unless you're planning on doing a lot of 4xhigh travel. What you need to insure is that you are getting a long travel front drive shaft to work in conjunction with the r/s.
Was considering the cv joint only because I feel that I will be able to achieve pinion and caster angles more accurately when I do the cut and turn. I have also read that the cv joints have a longer life span than a traditional u-joint shaft.
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Old 11-30-2012, 07:18 AM   #4
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Default Re: Calling all SOA conversion guys......

Quote:
Originally Posted by mikeindustries View Post
was considering the cv joint only because I feel that I will be able to achieve pinion and caster angles more accurately when I do the cut and turn. I have also read that the cv joints have a longer life span than a traditional u-joint shaft.
If you build your setup correctly a non-cv driveshaft can have good angles as well. And if the angles are correct a cv and non-cv joint will last the same length of time.

I've never run a cv driveshaft iin the 10+ different front axle configurations I have built/run.

As for the original question - I needed to lengthen my rear driveline when I did my 1st SOA many moons ago...
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Old 11-30-2012, 07:31 AM   #5
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Default Re: Calling all SOA conversion guys......

Quote:
Originally Posted by chris pucci View Post
if you build your setup correctly a non-cv driveshaft can have good angles as well. And if the angles are correct a cv and non-cv joint will last the same length of time.

I've never run a cv driveshaft iin the 10+ different front axle configurations I have built/run.

As for the original question - I needed to lengthen my rear driveline when I did my 1st SOA many moons ago...


/\/\/\/\/\

this.

I feel that for 90% of the spring over applications a cv front shaft is really a waste of money.
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Old 11-30-2012, 08:42 AM   #6
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Default Re: Calling all SOA conversion guys......

And to add if running an automatic there isn't enough clearance between the cv joint itself and the transmission oil pan. Most end up having to notch the pan which can lead to leaks.
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Old 11-30-2012, 11:04 AM   #7
mikeindustries
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Default Re: Calling all SOA conversion guys......

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Originally Posted by ihpartsjeff View Post
and to add if running an automatic there isn't enough clearance between the cv joint itself and the transmission oil pan. Most end up having to notch the pan which can lead to leaks.
That's a good heads up. Was going to get under it this weekend to take some measurements. Would like to have the new shafts on hand at axle swap time. I've never done a cut and turn before but as a pipefitter/welder I am sure I can figure it out. Just want it right the first time.

Last edited by mikeindustries; 11-30-2012 at 11:40 AM.. Reason: spelling
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Old 12-04-2012, 12:36 PM   #8
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Default Re: Calling all SOA conversion guys......

Hello IH friends...I have a few questions and would like some input from someone who has done a swap.

I am going to help a local friend put a d60 in front of his 1978 Scout II over the holiday. We have 'mocked it up' so far and have cut the knuckles to prepare for a caster adjustment.

Setup: 345/727/d20. SOA using stock springs. No reverse shackle (but open to it if needed)

we are not sure yet if we should point the pinion up to the t-case and use a cv shaft or run the yoke angles parallel to eachother and run a conventional single cardan style driveshaft.

My concern is with the pinion shaft length of the d60...that angle with a single cardan would be pretty extreme with an SOA...anyone have experience (searching didn't provide a definitive answer on this).

If the pinion points to the t-case...then the spring perches become a question - using an angle shim and the existing studs would then be a challenge without additional fab work beyond our skills.

And finally caster angles... From Chad here at IHPA: 5* on the passenger side and 4.75* on the driver still the way to go?

We May extend the wheelbase to make room for bigger tires with less lift...any suggestions on which springs or hanger modifications to use if we have to go that route?
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Old 12-04-2012, 01:02 PM   #9
mikeindustries
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Default Re: Calling all SOA conversion guys......

Quote:
Originally Posted by brett View Post

Setup: 345/727/d20. SOA using stock springs. No reverse shackle (but open to it if needed)

we are not sure yet if we should point the pinion up to the t-case and use a cv shaft or run the yoke angles parallel to eachother and run a conventional single cardan style driveshaft.

My concern is with the pinion shaft length of the d60...that angle with a single cardan would be pretty extreme with an SOA...anyone have experience (searching didn't provide a definitive answer on this).

If the pinion points to the t-case...then the spring perches become a question - using an angle shim and the existing studs would then be a challenge without additional fab work beyond our skills.

We May extend the wheelbase to make room for bigger tires with less lift...any suggestions on which springs or hanger modifications to use if we have to go that route?
Hijacked......

I looked at mine over the weekend. I only have about 3/4" from the side of my front stock drive shaft to the side of the trans oil pan. Also the x-member for thetrans mount is very close. No way a cv shaft will fit without fabing a new x-member and a cut and mod on the trans oil pan.
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Old 12-04-2012, 01:10 PM   #10
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Default Re: Calling all SOA conversion guys......

Didn't intend to hijack, just felt no need to have another topic about SOA. Thanks for the info.
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Old 12-04-2012, 02:44 PM   #11
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Default Re: Calling all SOA conversion guys......

You could point the pinion up and then run a standard driveshaft. That is the el-cheapo setup.
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Old 12-04-2012, 03:02 PM   #12
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Default Re: Calling all SOA conversion guys......

Quote:
Originally Posted by chris pucci View Post
you could point the pinion up and then run a standard driveshaft. That is the el-cheapo setup.
Great site you have chris. That is what we have been using for our diy.

So...mikeindustries...my opinion is you will need a new driveshaft.

Have you considered your wheel base? Are you going to keep at 110" or extend the rear also? I believe with a reverse shackle you will gain 2" in the front (please correct me if I am wrong). If that is the case I May do the same to help with firewall clearance on full stuff.

We used a 14bff in the rear of this project and extended 2.5" in the rear...easier to do cutting of the wheel well for a good stuff with the 37s.
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Old 12-04-2012, 03:57 PM   #13
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Default Re: Calling all SOA conversion guys......

A non cv shaft will actually run at steeper angle than a cv shaft. The cv shaft is meant more for compound angles...ie if you have not only a down angle but maybe your diff is not in line with the output of your t-case.

I agree with the not needing a cv shaft in the front. In my Jeep comanche pickup I am running 10" of lift and I run a non cv shaft up front...I can stuff the 35's all the way into the fenders and have about the same amount of down travel. The front non cv shaft has held up fine.

If you were running a later model truck with a unit-bearing style hub assembly on the front end then you May need something else but chances are you aren't running that type and have the manual locking hubs. The only time that shaft will even be spinning is if you lock in the hubs in 4wd and then you won't be going very fast.
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Old 12-04-2012, 08:46 PM   #14
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Default Re: Calling all SOA conversion guys......

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Originally Posted by brett View Post
didn't intend to hijack, just felt no need to have another topic about SOA. Thanks for the info.
I know.
I read at one of the previously links that you can run a standard drive shaft close to 30* .
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Old 12-05-2012, 07:07 AM   #15
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Default Re: Calling all SOA conversion guys......

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And finally caster angles... From Chad here at IHPA: 5* on the passenger side and 4.75* on the driver still the way to go?
Anything between 5 and 7 for caster is good. Just set them as close to the same as possible. :d
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