lemme guess..its been asked a million times. just a one word answer would be fine. i want to wheel damn it! if i make a square driveshaft because im a cheepass...i dont wanna have to make another longer one after. but if its gonna have to be shortened..ill just cut the bitch down!

--- i have soa w/ s/r if that means anything at all

It depends on if you are using a plate adapter or the AA 5" (I think) adapter. If you are usign the plate adapter you might have a slightly shorter DS, it will be close. With the AA adapter then you will certianly need a longer driveshaft. Also if you just did a SO and the SR you will probably need a long travel driveshaft..

i have a [plate adapter..a wardens to be specific. the reason im gonna do a square is because i need long travel. and im cheap cheap cheap!

--- also..im still left w/o an answer. i just need to know if its gonna be shorter or longer so much that ill need to rebuild my d-line if i make it be4 the 420 swap. thanks!

what drivetrain (tranny) were you using before? I believe if you were using a three speed then it will need to be longer, but if you were using a four speed then the 420 with the plate adapter should put you real close to the same as before. did you already have to lenghten them from the SO, or have you got that far yet?

Not to point out the obvious by why not make your dl after the swap? It's only a square so it shouldn't take that long to build...

like i said..i want to wheel damn it. thats why. if it is gonna force me to make it again to have it longer..then fawk it, ill wait. but i wanna go...shit.

--- ok, how much compression will the shaft need? then i can sacrifice some and..well the idea is in my head i cant explainbe. just how much stuff does it need? thanks!

If you go from a Cruiser 4-spd to an SM420 + plate adapter like you have, it is almost in the same spot. I think it ends up being 1/2" shorter in the front or maybe a bit less. If you have enough travel in the front, it won't really matter.

Yes your front driveshaft will need to be lengthed. But until you finish the transmission conversion you can't attempt to get the mesurement.
Mike:D :D

With Danny Warden's plater, there is less than 3/4" difference - closer to 1/2". So, you should be ok for your DL's - I know I was ok on mine.

Look at it this way, The adapter plate is about 3/4" thick, so that means that the rear out put will be that much closer the the rear pinion, and the front output will be that much further away from the front pinion.

So the answer is YES, you will need to lengthen your front shaft not only the 3/4", but the other 3/4" or so since its really your rear shaft not your front, and ofcourse the 6 inches or so of lift you've obtained with the SOA. Remember that the stock front shafts for the 3spds are about 3/4" longer than the rear shafts, and I swapped your front with your rear.

Jeff

As Dustin has a 72' Cruiser I assumed he had the stock 3 spd trans in it. Since they are approx. 2" shorter than the sm420, with the addition of the plate adapter that means the t-case is approx 2 3/4" further back than the stock position.
Mike;)

take and messure the distance from the back of the first tranny to the end of it.Then take the new messurements and subtract the two.Hope this helps.

LONGER

I went from a 3 speed tranny to an SM420 using a plate adapter and also did the spring over at the same time. My Driveshaft is WAY longer than stock. I can measure it tonight if you want.

ok, ko, ok....
i know i need a way longer one since im soa and i know it needs gobs pof travel...thats not my question. i was just asking...if i built a d-line now...how will it need to be changed after i do my sm420. thanks guys...

Originally posted by DCruiser138
ok, ko, ok....
i know i need a way longer one since im soa and i know it needs gobs pof travel...thats not my question. i was just asking...if i built a d-line now...how will it need to be changed after i do my sm420. thanks guys...

If you're going from a three speed tranny to an SM420. Yes it will have to be longer after the change is completed (Isn't that what I said? ;)

:D:D:D:D