1-ton swap

[Shack]

Welding cast perches can be tricky, you have to use high nickel rod and cool the weld slowly or it will just crack at the weld. If it was me I would source another axle from a 3/4 ton, or buy some stamped perches to weld on. As far as driveline angle your tcase output and pinion angles should match or be close. If it looks like your tcase output points down a little your pinion should point up the same degree. This is why the front uses a double cardan joint. The tcase output up front just about always points up a little so 2 joints on the tcase side helps eliminate vibration.

Perfect. When the time arrives, I will refer back to here and ask again juts in case I forget. lol Thanks!

 

[Greybeard]

Originally Posted by crazy4offroad
Welding cast perches can be tricky, you have to use high nickel rod and cool the weld slowly or it will just crack at the weld. If it was me I would source another axle from a 3/4 ton, or buy some stamped perches to weld on. As far as driveline angle your tcase output and pinion angles should match or be close. If it looks like your tcase output points down a little your pinion should point up the same degree. This is why the front uses a double cardan joint. The tcase output up front just about always points up a little so 2 joints on the tcase side helps eliminate vibration.

Perfect. When the time arrives, I will refer back to here and ask again juts in case I forget. lol Thanks!

What crazy4offroad said^^^
One point about the t-case angle, some folks drop the tail of the t-case to ease rear driveshaft angle, however, this also increases the 'upwardness' of the front output. This also moves the distributor closer to the firewall, might cause interference with the fan shroud and the list goes on...Ain't life a beach? Nevertheless, I lowered the rear of my t-case 1" due to a six inch lift with no ill effects on my old 78. I did, however, have to relieve small areas on the front CV joint (Saginaw style) to accommodate the droop of the front axle. YMMV. My truck was a SWB though. I guess that was more than one point...

 

[Shack]

[QUOTE
One point about the t-case angle, some folks drop the tail of the t-case to ease rear driveshaft angle, however, this also increases the 'upwardness' of the front output. This also moves the distributor closer to the firewall, might cause interference with the fan shroud and the list goes on...Ain't life a beach? Nevertheless, I lowered the rear of my t-case 1" due to a six inch lift with no ill effects on my old 78. I did, however, have to relieve small areas on the front CV joint (Saginaw style) to accommodate the droop of the front axle. YMMV. My truck was a SWB though. I guess that was more than one point...[/QUOTE]

1. No distributor here (5.3 Vortec).
2. Fan shroud is built into the radiator I purchased with electric fans. That shouldn't be an issue.
3. How did you lower just the rear of the t-case and how did you relieve the stress up front?
4. Mine's an SWB as well.
5. I've since decided I will go with a 6 or 8 inch lift and run 35x16x16 (if I can get the 16" wheel to fit the 8-lug without spacers. I think the 8" should clear them. We'll see.

 

[crazy4offroad]

If you look at the t-case cross member there should be some 1" spacers on the top side of the frame. Put a jack under the cross member, remove the bolts, lower the cross member a little more than an inch and put the spacers between the frame and cross member. You just gained an inch of drop in the back.

To relieve the front angle (this is what I did at least) take a carbide burr bit with a long shank and clearance the contact pads in the double cardan joint. You might put a jack under the center of the front bumper and take it up till the axle is at full droop then spin your front shaft and you'll see the contact pads if you have interference. Be sure to wear leather gloves, long sleeves and eye protection, and use compressed air to blow out the cuttings. The burr bit makes them like tiny needles. Get them all over you and you'll be in a hell of a mess.

Another alternative is to install a 1350 pinion yoke, then source a front driveshaft from a Dodge 2500, around a 2005 model. They have a double cardan like ours but it runs 1350 joints in it unlike ours with the wimpy 3R joints, allowing between 30-35 degree running angle, much more than ours can do stock. You'll have to have a driveline shop cut it down a few inches but it will be much stronger than our stock front driveshafts.

 

[Greybeard]

If you look at the t-case cross member there should be some 1" spacers on the top side of the frame. Put a jack under the cross member, remove the bolts, lower the cross member a little more than an inch and put the spacers between the frame and cross member. You just gained an inch of drop in the back.

To relieve the front angle (this is what I did at least) take a carbide burr bit with a long shank and clearance the contact pads in the double cardan joint. You might put a jack under the center of the front bumper and take it up till the axle is at full droop then spin your front shaft and you'll see the contact pads if you have interference. Be sure to wear leather gloves, long sleeves and eye protection, and use compressed air to blow out the cuttings. The burr bit makes them like tiny needles. Get them all over you and you'll be in a hell of a mess.

Another alternative is to install a 1350 pinion yoke, then source a front driveshaft from a Dodge 2500, around a 2005 model. They have a double cardan like ours but it runs 1350 joints in it unlike ours with the wimpy 3R joints, allowing between 30-35 degree running angle, much more than ours can do stock. You'll have to have a driveline shop cut it down a few inches but it will be much stronger than our stock front driveshafts.

Good overall advice. I do have a small debate even though I agree with your premise to gain stronger u-joints. The point I want to make is about the weakest link. Do you want to replace the easiest to replace link or the hardest one? The driveshaft u-joints are easy, the steering joints are not. I want my weakest link to be something I can get home with despite it breaking. This may or not be possible when a steering joint breaks. It's a PITA changing a steering u-joint in the sand or mud or worse yet- a trail full of snow.

It just shows that the overall design has to be considered. I put a 400 horsepower 355 in my K10 back in the day, still had the stock 12 bolt, that didn't last long, put in a car 12 bolt with four spider and a posi, it didn't last a six months with 36" tires, went to the 14FF with a Gov lock. Then started busting my driveshaft, two shafts later I went to a big truck shop and told the what I wanted, they got the parts and fixed it up- never broke another driveshaft, It has sm 465 and a np205 in it so that was rock solid. I bused a lot of front driveshaft u-joints, but never did bust a front steering u-joint in the seven years I owned that truck. A $10 dollar and twenty minute fix as opposed to a $20 dollar and three hour plus fix (if all goes well). Just sayin...

 

[Shack]

If you look at the t-case cross member there should be some 1" spacers on the top side of the frame. Put a jack under the cross member, remove the bolts, lower the cross member a little more than an inch and put the spacers between the frame and cross member. You just gained an inch of drop in the back.

To relieve the front angle (this is what I did at least) take a carbide burr bit with a long shank and clearance the contact pads in the double cardan joint. You might put a jack under the center of the front bumper and take it up till the axle is at full droop then spin your front shaft and you'll see the contact pads if you have interference. Be sure to wear leather gloves, long sleeves and eye protection, and use compressed air to blow out the cuttings. The burr bit makes them like tiny needles. Get them all over you and you'll be in a hell of a mess.

Another alternative is to install a 1350 pinion yoke, then source a front driveshaft from a Dodge 2500, around a 2005 model. They have a double cardan like ours but it runs 1350 joints in it unlike ours with the wimpy 3R joints, allowing between 30-35 degree running angle, much more than ours can do stock. You'll have to have a driveline shop cut it down a few inches but it will be much stronger than our stock front driveshafts.

Good overall advice. I do have a small debate even though I agree with your premise to gain stronger u-joints. The point I want to make is about the weakest link. Do you want to replace the easiest to replace link or the hardest one? The driveshaft u-joints are easy, the steering joints are not. I want my weakest link to be something I can get home with despite it breaking. This may or not be possible when a steering joint breaks. It's a PITA changing a steering u-joint in the sand or mud or worse yet- a trail full of snow.

It just shows that the overall design has to be considered. I put a 400 horsepower 355 in my K10 back in the day, still had the stock 12 bolt, that didn't last long, put in a car 12 bolt with four spider and a posi, it didn't last a six months with 36" tires, went to the 14FF with a Gov lock. Then started busting my driveshaft, two shafts later I went to a big truck shop and told the what I wanted, they got the parts and fixed it up- never broke another driveshaft, It has sm 465 and a np205 in it so that was rock solid. I bused a lot of front driveshaft u-joints, but never did bust a front steering u-joint in the seven years I owned that truck. A $10 dollar and twenty minute fix as opposed to a $20 dollar and three hour plus fix (if all goes well). Just sayin...

Lots of great info guys!! I'm definitely a fan and always have been of having my weakest link something that's easy to fix and relatively inexpensive for that very reason.

Carbide bits are amazing but the mess they generate. I've been down that road in the past. Thanks again, like I said, a lot of great info!!

 

[JIMs86K5]

My 1 ton swap

I put CUCV axles under my 86. I bought new perches from Offroad Design as well as top plates and u-bolts for the rear. Had to relocate the shock mounts too.

 

[JIMs86K5]

new perches

A couple shots from when I welded the new perches on.

 

[HotRodPC]

I think also part of the reason of the being level suggestion for a 14 bolt is for making sure the pinion bearing is getting oiled. I heard the same about being level or close to it at one time.

For ease of installation, and as common as 3/4 ton 14 bolts are, I'd wait for the direct bolt in swap. Of course with that much lift, if you're going to be changing the angle, then it doesn't matter, use what you have.


EDIT: OK as usual, I'm late to the party. I see you already got the perches moved now. Installed it yet?

 

[stlbob]

plasma cleared all the old perchs off and got new ones,used angle finder to get it right the first time..a lot of extra work just had to have it right the first time.It really turned out nice no axle wrap or twisted up feeling on a tight curves..

 

[theblindchicken]

I've just got a 3/4t 14bff waiting to go in.... haven't made the decision whether to convert to the 14bff to 6 lug, or convert the d44 to 8 lug.

Sure do love my slot mags, but they're nearly impossible to find in a set of 8 lugs.

 

[HotRodPC]

I've just got a 3/4t 14bff waiting to go in.... haven't made the decision whether to convert to the 14bff to 6 lug, or convert the d44 to 8 lug.

Sure do love my slot mags, but they're nearly impossible to find in a set of 8 lugs.

Is there a way to convert a 14b FF to 6 lug? If there is, I'd damn sure do that instead of looking for all these parts to convert the 10 bolt to 8 lug on mine. I've got 6 lug wheels, and @irishman666 has some nice wheels for me if I go 6 lug. I'd like to run the cheaper tires and I like the size options in 15in better too. So if I do this, then I really won't have a K20 conversion. It'll just be a 14b Full Float rear axle and 3/4 ton C6P rear springs. I want the heavier capacity plus the little lift I'll gain from the 3/4 ton 56in springs. So how does this 6 lug conversion work? Just redrill the axles or what? I have a disk brake conversion kit for the 14b FF too, so I think I can run the 15in wheels if I convert it to rear disks. Rear disks and 6 lug on my 14b FF would be great for several reasons.

 

[theblindchicken]

Is there a way to convert a 14b FF to 6 lug? If there is, I'd damn sure do that instead of looking for all these parts to convert the 10 bolt to 8 lug on mine. I've got 6 lug wheels, and @irishman666 has some nice wheels for me if I go 6 lug. I'd like to run the cheaper tires and I like the size options in 15in better too. So if I do this, then I really won't have a K20 conversion. It'll just be a 14b Full Float rear axle and 3/4 ton C6P rear springs. I want the heavier capacity plus the little lift I'll gain from the 3/4 ton 56in springs. So how does this 6 lug conversion work? Just redrill the axles or what? I have a disk brake conversion kit for the 14b FF too, so I think I can run the 15in wheels if I convert it to rear disks. Rear disks and 6 lug on my 14b FF would be great for several reasons.

https://www.sneveysoffroad.com/gm_14_bolt_ff_6_lug_conversion_kit/4_wheel_parts_off_road_parts

It's a full disk conversion for it, but instead of the typical 8 lug conversion, it's to 6 lug.

 

[HotRodPC]

Yikes, very pricey. It appears I'd be better off using my disk brake kit I already have on the standard 8 lug hub. I think I can still convert the front axle to 8 lug and then find some 15 inch 8 lug wheels later on when I buy tires.

 

[theblindchicken]

Yikes, very pricey. It appears I'd be better off using my disk brake kit I already have on the standard 8 lug hub. I think I can still convert the front axle to 8 lug and then find some 15 inch 8 lug wheels later on when I buy tires.

Super pricey, and you still need rotors, calipers, and all the other goodies.

Isn't that only a little bit higher than the cost of 8 lug swapping a 6 lug d44?