SAS front driveshaft help

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toy4x4runner

toy4x4runner

10 Year 15 Year
Joined
Oct 1, 2007
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18
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84
Location
derry NH
I am a little over half way through installing trail gears 3" SAS kit on my 87 4Runner. I am wondering what people have experienced with this or similar builds. I don't know if i can get away with just extending a 84-85 front shaft or if i will have to get a longer spline solution. The cost of the front shaft slipped my mind when planing for this project. So i am trying to keep it cheep.

Also curious to see if anyone here has modified a IFS front driveshaft to have more flex. Or went the square tube route and can tell me what kind of vibrations may have experienced.
Thanx!
 
seems like you could take the ifs shaft to a drive shaft place and have them lengthen it pretty easily.

that way you retain factory parts that you can easily replace if you break a u joint or something. plus it already has the cv at the top.

while i have no experience with square drive shafts, it seems to me they would rattle at higher speeds. and you could probably forget about getting the thing balanced. then you have to either reuse the flanges and cv from your existing shaft, or buy new ones.

and at that point, i dont see why you wouldnt just use the oem one to begin with. seems like less work to me.
 
The problem with the IFS shaft is the CV has a lot less flex built in. Not a problem for an IFS rig where the diff stays stationary, but on a SA, depending on how much flex your suspension has, you need the driveshaft to have more flexibility at the CV end.

Steve, here's an article I found about the conversion: Driveshaft CV Modification for Increased Angle

(OP is my son, BTW. He doesn't get on here much, usually he just calls me)
 
bryan89 said:
while i have no experience with square drive shafts, it seems to me they would rattle at higher speeds. and you could probably forget about getting the thing balanced. then you have to either reuse the flanges and cv from your existing shaft, or buy new ones.
Click to expand...

I do not know if they would make a noise at highway speeds, seems plausible but I have not heard of anyone I know complain about that.

You would have to reuse the flanges, and cv if needed. As far as balancing i've been told by the ones who run them that there is no balancing needed. Just make sure the flanges are welded true. The big benefit (for a trail rig) is they are super stout. You can make as much slip as you want, and if you use two 1/4 pieces (one inside the other) that's 1/2" wall thickness.

The other cool factor with that much slip is that you can make one spare and use it for the front or the rear.

If you go with tubing, make sure to add a zerk fitting to the tubing so it can be greased.
 
I'm recommending to him that he NOT go the homebrew square tubing route. Two reasons: this truck is his daily driver, so he will have some times when he will need the hubs locked at highway speed. This truck is in fantastic condition, not a trail beater. He also very new at welding (just did his first weld on Sunday), and I don't think he has access to a metal chop saw, so I doubt he'd get the thing well centered on his first try.

I believe he is moving his axle 2" forward (as I did), so I think even if he does find an older SA driveshaft, it will need to be re-tubed (as mine did).
 
If i went the square tube route it would only be a temporary solution to get the truck on the road until i could get a real one made. I do have access to a chop saw so I can probably get it relatively straight. Brookline Machine gave me a quote for extending the length at about $120. I also have 2 IFS fronts to play with. Does anyone know if the spline on a IFS driveshaft is shorter then a pre 85?
 
To clearance an IFS shaft to have more travel and a SFA shaft isn't hard. If you have one sitting around, its easy enough to try and do.

From a travel standpoint: there isn't enough travel in a stock driveshaft to accommodate a longer travel front suspension. So if your running over 8" travel shocks, your probably going to need a longer slip yoke.

I have a driveshaft kit from all pro (https://www.allprooffroad.com/pickupdrivetrain/31) and still have good results after 4 years.
 
All useful info. I will be messing with some ISF shafts tomorrow and the next day. Ill post updates with any luck.
 
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