length difference in 70 6cyl swb driveline to sbc line?
 

got a project a 70 steppy came with 305 and TH350 out of a 83 firebird- dont ask
was originally a 6cyl 3spd -longer motor hence my drive shaft is too short (about 56" center to center of jonts- 'about')

a stock 1 piece driveline from sbc motor ahould work right? i dont want to lengthen too much $ and there are lots of boneyards around, i can use u jonts i have..

how long is stock driveline for shortbed v8?

thanks guys!
and yes i searched- so much info here my head hurts

Re: length difference in 70 6cyl swb driveline to sbc line?
 

All the shortbed v8 auto trucks I've seen have a 2 piece driveshaft with a center support bearing. All the 6cyl straight shift trucks I've seen have had a 1 piece driveshaft.

With that being said... I haven't seen every truck ever built and I'm not an authority on them.

Re: length difference in 70 6cyl swb driveline to sbc line?
 

I believe the V8s are mounted a bit forward relative to the 6 cyl mounting. But I guess you know that since your driveshaft is too short.

If you in an area that has junkyards then a V8 driveshaft might be available. Where I live there are no junkyards with these old trucks so had a new driveshaft made up by a shop (I didn't swap motors but changed trannies and new tranny was longer).

Re: length difference in 70 6cyl swb driveline to sbc line?
 

Best to get under the truck and measure it yerself so you can blame the right person if it dont fit

Re: length difference in 70 6cyl swb driveline to sbc line?
 

yes the v8 mounts are forward of the 6 mounts in the frame. so no real way to know what a 1 piece DL for small block is since no such stock animal

ok well the 2 piece driveshaft for v8s now poses another problem- more parts haha is it completely necessary to go 2 piece? not running big HP...

i could measure tail to diff but whats the slipjoint tolerance and its lowered so less angle than normal...
maybe i am stuck with driveline shop and thier services. dang

thanks guys

Re: length difference in 70 6cyl swb driveline to sbc line?
 

One piece works fine for me, mine was too long when it snapped, now its to proper poportions and has not given me any issue yet

Re: length difference in 70 6cyl swb driveline to sbc line?
 

thats good to know. did you have is shortened? what is length now? tranny?
thanks

Re: length difference in 70 6cyl swb driveline to sbc line?
 

The one i had was 60 inches but i found one that was 58 inches from a junkyard from some unknown vehicle. i have a turbo 350 trans and my engine is in the 6cylnder position, id take a tape measure and double check how far you need to go, just remember to compensate for suspesion travel or you will run into the same issue i had

Re: length difference in 70 6cyl swb driveline to sbc line?
 

blackedout- ouch yeah dont want that.

you running 58" line now? from pix in your build thread your motor is in correct forward v8 mount holes....

Re: length difference in 70 6cyl swb driveline to sbc line?
 

Damn your right:thud: I kept thinking it was in the six cylinder position since I was a inline six truck but I forgot that I changed it, I guess the mind wonders off when ya work third shift :lol:

Re: length difference in 70 6cyl swb driveline to sbc line?
 

blackedout- haha thanks understood and agreed

58" working now?

Re: length difference in 70 6cyl swb driveline to sbc line?
 

My son has a 72 LWB with a 305 and turbo 350 from a 75 monty carlo. It has leaf springs. We used a one piece drive shaft. However we torched the center crossmember elongated the hole so the driveshaft wouldn't rub.

Re: length difference in 70 6cyl swb driveline to sbc line?
 

Yuppers the 58 inch has not given me a problem, the issue was when I bought my truck they lowered it all the way around and didn't think the driveline would be an issue, I drove it for three years like that till I was on the interstate going 75 and hit a bump while turning and well lets just say even though it was unfortunate I am very lucky the driveshaft didn't catch on a bump in the road:lol:

Re: length difference in 70 6cyl swb driveline to sbc line?
 

thanks guys! when i got this truck they guy that sold it to me had a few others , blazer, suburban ll same gen- said this forum was the best and folks here are fantastic. so far i agree

thank you, ill be back soon im sure haha

Re: length difference in 70 6cyl swb driveline to sbc line?
 

What's wrong with staying with a two piece driveshaft.? The big rigs use them and so, seems to me, that they are strong. And wouldn't a two piece make it easier for a lowered truck.?

Just asking..I don't know the answer to this...

Re: length difference in 70 6cyl swb driveline to sbc line?
 

'staying with a 2 piece driveline' implies i already have one...

Re: length difference in 70 6cyl swb driveline to sbc line?
 

Have a shafy made the correct length for your truck. They aren't that expensive when compared to driving to a junkyard, buying a shaft, putting new joints in the shaft, and having the shaft ballanced IF its the correct length and wasn't hurt in an accident or by the fork lift operator.....

I try to run a one piece whenever I can but I have built many 4, 5, and 6 piece shafts, nothing wrong with multile piece drielines when they are properly built and engineered.

Re: length difference in 70 6cyl swb driveline to sbc line?
 

ok i measured more / again whats that saying?

60" center of rear u joint (on diff) to end of th350 tailhousing (6" housing)
the shaft i have measures 61" to end of (3") yoke - 1 inch would go inside.

if the rule is 1 inch between that would normally leave 2" overlap inside for slip correct? ( i understand there are 3" and 9" tail housings for different applications which prob need less and more slip like cars and 4x4s respectively?)

so i could theoretically get a 1" longer yoke? or maybe a bit more? what ya think? disclaimers for all haha

benefit of a lowered swb 2wd is not much angle to deal with...

thanks fellas!

Re: length difference in 70 6cyl swb driveline to sbc line?
 

Longer yoke, still leaves a lot of yoke hanging out the back of the trans. If your trans bushing isn't tight it won't last long. Especially if its not ballanced. Give the shaft you have to a driveline shop with your measurements and have them retube and ballance using your weld and trans yokes.

Re: length difference in 70 6cyl swb driveline to sbc line?
 

its only an inch or so short so i dont see a big rotating mass problem especially since its in a more parallel orientation than stock (lowered and more in line with crank/tranny rotation) not running lots of hp or torque. and at this point a new yoke is simple and cheaper than driveline services. in future it may need addressing but there are lots of other things more pressing- like getting it to run?!

thanks for all the help guys

Re: length difference in 70 6cyl swb driveline to sbc line?
 

New yoke would still require ballancing.