Lets talk front driveshaft drive angles with the SM465, np205 & 10bolt corporate axle

[Wilfred]

Hey all,

I removed my AT (700R4) and transfer case (np208) and installed an SM465 MT and np205 transfer case. In the process, I had to move the cross member that holds up the adapter between the transmission and transfer case forward about 2". The truck suspension imight be lifter like 4" I see that I have a couple extra leafs in my leaf springs so..... CV output flange on the transfer case is pointed up at a 4 degree angle. The yoke on the front diff is also pointed up at a 4 degree angle. The center of the CV flange is approximately 7" higher from a level line off the center of the yoke on the front diff. The center of the CV flange is approximately 26" away from a vertical line off the center of the U Joint cap on the front diff. The U Joint at the diff is a 1310 to 1330 adapter (Spicer part # 5-134X) and there is a double cardan at the transfer case that uses two 1350 U Joints (Spicer Part # 5-1350X). There is a 6 inch slip yoke in between the front and rear portions of the drive shaft. I realize in this set up that the differential is pointing in the neighborhood of 4" - 4.5" below the double cardan joint which is not ideal. This is causing a lot of undue stress to the front diff to driveshaft U Joint (I am sure of it but am I wrong?) but if I start to shim the spring perches on the axle to rotate the diff up towards the double cardan I start to loose caster angle making my steering more precarious which I would like to avoid. If I were to remove the double cardan now I have to rotate the axle down 8 degrees to match the transfer case causing entirely too much caster angle - assuming no clearance issues with the drive shaft and cross member that the double cardan helps avoid.

Does anyone have any ideas?! Am I doomed to replacing the 1310 to 1330 U Joint every 3 to 6 months for all eternity cause i'm to cheap to spend money on a high pinion axle or to get my spring perches/steering knuckles rotated on my axle by a machine shop. To be honest I don't think the movement of the cross member has made much of a difference on the geometry but it certainly didn't help.

 

[Wilfred]

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[TubeTruck]

Does your crossmember have spacers? I know all the Squarebodies that I have had have spacers in the C channel of the frame. I've swapped them down between the frame and crossmember. Probably not ideal but see if that helps. You might get a little more upwards angle off the T-case but it might lower your driveshaft enough to not bind?

 

[AuroraGirl]

Does your crossmember have spacers? I know all the Squarebodies that I have had have spacers in the C channel of the frame. I've swapped them down between the frame and crossmember. Probably not ideal but see if that helps. You might get a little more upwards angle off the T-case but it might lower your driveshaft enough to not bind?

where should they go? the spacers?

 

[TubeTruck]

where should they go? the spacers?

I had one truck where they were between the frame and crossmember and my Suburban has them in the frame. No idea where the factory put them. I would think inside the frame like my Suburban would be correct.

 

[SquareRoot]

GM made lots of manual trans equipped 4wd square bodies. 205 or 208 t-cases. What did they use?

 

[fast68chevy]

1983 changed to W crossmemer and 32 spline output shaft, even with the 465 tranny.. tons of info and threads posted even the forums here all about this very exact thing. the 1983 up adapter has short length foot casting for the W crossmember that have the taller/more upwards center of the crossmember..
unlike the old 1982 older ones that are flat and lower..

this is with the 208 case trucks anyways.. and i have owned driven daily one original untocuhed 1983 K20 with 465 and 208 bone stock original totally.. it as 32 spline output shaft and W crossmember still factory correct.

 

[fast68chevy]

Does your crossmember have spacers? I know all the Squarebodies that I have had have spacers in the C channel of the frame. I've swapped them down between the frame and crossmember. Probably not ideal but see if that helps. You might get a little more upwards angle off the T-case but it might lower your driveshaft enough to not bind? ok well

ok, well that was for 1982 and older adapters and 208 cases 465 trannies.,.,. but '83 up went to W crossmember and short height adapter footing casting.. no spacers or anything anymore,, at least with 465 208 anyways,,

 

[fast68chevy]

You must be registered for see images attach

that is an 82 and older. or non-W crossmember,.

 

[fast68chevy]

and there are good and correct and better ways to lower the T case etc to correct driveline angles and distance from yoke to yokes..etc.

 

[bucket]

1983 changed to W crossmemer and 32 spline output shaft, even with the 465 tranny.. tons of info and threads posted even the forums here all about this very exact thing. the 1983 up adapter has short length foot casting for the W crossmember that have the taller/more upwards center of the crossmember..
unlike the old 1982 older ones that are flat and lower..

this is with the 208 case trucks anyways.. and i have owned driven daily one original untocuhed 1983 K20 with 465 and 208 bone stock original totally.. it as 32 spline output shaft and W crossmember still factory correct.

You don't go read posts when people quote your posts, do you?

 

[bucket]

Hey all,

I removed my AT (700R4) and transfer case (np208) and installed an SM465 MT and np205 transfer case. In the process, I had to move the cross member that holds up the adapter between the transmission and transfer case forward about 2". The truck suspension imight be lifter like 4" I see that I have a couple extra leafs in my leaf springs so..... CV output flange on the transfer case is pointed up at a 4 degree angle. The yoke on the front diff is also pointed up at a 4 degree angle. The center of the CV flange is approximately 7" higher from a level line off the center of the yoke on the front diff. The center of the CV flange is approximately 26" away from a vertical line off the center of the U Joint cap on the front diff. The U Joint at the diff is a 1310 to 1330 adapter (Spicer part # 5-134X) and there is a double cardan at the transfer case that uses two 1350 U Joints (Spicer Part # 5-1350X). There is a 6 inch slip yoke in between the front and rear portions of the drive shaft. I realize in this set up that the differential is pointing in the neighborhood of 4" - 4.5" below the double cardan joint which is not ideal. This is causing a lot of undue stress to the front diff to driveshaft U Joint (I am sure of it but am I wrong?) but if I start to shim the spring perches on the axle to rotate the diff up towards the double cardan I start to loose caster angle making my steering more precarious which I would like to avoid. If I were to remove the double cardan now I have to rotate the axle down 8 degrees to match the transfer case causing entirely too much caster angle - assuming no clearance issues with the drive shaft and cross member that the double cardan helps avoid.

Does anyone have any ideas?! Am I doomed to replacing the 1310 to 1330 U Joint every 3 to 6 months for all eternity cause i'm to cheap to spend money on a high pinion axle or to get my spring perches/steering knuckles rotated on my axle by a machine shop. To be honest I don't think the movement of the cross member has made much of a difference on the geometry but it certainly didn't help.

So to put it shortly, you are mainly concerned with the angle on the u-joint, correct? Imho, just run it with a good quality joint and it should be fine. With those beefy looking springs, you probably won't have much axle droop.

 

[Wilfred]

I think the 4" lift is my "problem". I am going to try a 2 degree shim between the springs and the spring perches. I can't lower my cross member because the distributor cap is just about hitting the firewall as it is.

 

[Greybeard]

You are seriously overthinking it. A 4" lift is marginal at best, it doesn't bother the driveshaft angle much at all. With a short lift like that there will/should be zero binding even with a jump joint at full droop.

I took an automatic with a 208 out and replaced it with a NP465 and 205 in my short box. 6" lift was no problem with 38" tires. I did have to space the cross member down an inch with store bought pipe couplers that fit over the longer bolts. Leave the stock spacers where they are if they are still there. If I remember correctly the cross member was mounted inside the rails as stock and had to be moved to under the rails with the 4" lift but the 6" lift required that extra 1" drop. However, that was eons ago, I might be misremembering. Granted, this was on a pre-80 truck with Dana 44 diff but there shouldn't be much difference between diff's to my knowledge. A 10 bolt and 44 are nearly identical in size.

I'm sure you are aware that there may be limitations to how much you can lower the cross member due to interference in the engine compartment (fan to shroud, possibly distributor cap, exhaust connections, etc.) and as you expected, any lowering at the rear does impact the drive shaft angles, but in reality it's not terrible.

There's always the option of using limiting straps...it's less expensive than high angle joints. My guess is you don't have very much travel anyway with stock length shackles. It looks like you have two add-a-leaves installed (maybe not), those stiffen the ride so much you likely have even less travel than before the lift.

As always---- YMMV