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Help! About To Do A Sunrader Axle Swap From 90-83. What Do I Need To Know?


AbleThought

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Hi, I have a 1983 Toyota sunrader 22-R 2x4. I managed to source out a 1990 6lug full floating axle that came off a 1990 Toyota dully pickup. Myself and a friend ( way more of a mechanic than I ) are going to do the job. What do I need? I am told a universal pinion-flange adaptor and seal... Where can I get this? Car part places are totally confused. Anything else? Am I going to be welding? Are things going to line up ok? I don't have the luxury of pulling it all apart and leaving it for a while as its being done at a friends house and I'm hoping to have everything needed to get the job done.

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You probably have to make a lot of changes to make it fit. Here's what I know or think I know. Double-check.

#1. 1983 and 1990 trucks use the same universal joints. Same joints are used 1979-1995. So I assume the bolt pattern on your existing driveshaft flange will line up with the holes in the pinion flange on the 1990 rear-axle-assembly. But . . Toyota increased the size of the bolts in 1984 from 8 mm to 10 mm. So - at the least -you'll have to drill out the flange on your driveshaft so 10 mm bolts will fit. If it IS a different pattern - many places sell universal-fit pinion flanges. Unless you really know what you're doing - it is easy ruin a rear-axle by trying to change a pinion flange or seal. One addition note. You can just take the entire differential center-section from your semi-floater rear and stick it into the full-floater. Then have NO issues with the driveshaft fitting.

#2. In 1986 - Toyota made the rear-axle assembly 2 1/4" longer and the leaf-springs wider apart. So a 1990 axle will NOT line up with the springs on a 1983. That means you have to cut the spring perches off the 1990 full-floater and weld them back on closer together. Your 1983 probably has the springs on 37" center-to-center. The 1990 will be 39 1/4" center-to-center. If you do this - you have to make sure that the perches are welded on with exactly the same plane as before. This is so the angle of the differential pinion centerline is correct.

#3. In 1986 - Toyota increased the outer-diameter of the tubes in the rear axle assembly to increase weight-capacity. The 1983 tubes are likely 2 1/2" diameter. The 1990 tubes are 3 1/8" outer diam

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I accidentally posted before done. I'll try again. Happens a lot to me recently. My grubby fingers don't work well with keyboards anymore.



#1. 1983 and 1990 trucks use the same universal joints. Same joints are used 1979-1995. So I assume the bolt pattern on your existing driveshaft flange will line up with the holes in the pinion flange on the 1990 rear-axle-assembly. But . . Toyota increased the size of the bolts in 1984 from 8 mm to 10 mm. So - at the least -you'll have to drill out the flange on your driveshaft so 10 mm bolts will fit. If it IS a different pattern - many places sell universal-fit pinion flanges. Unless you really know what you're doing - it is easy ruin a rear-axle by trying to change a pinion flange or seal. One addition note. You can just take the entire differential center-section from your semi-floater rear and stick it into the full-floater. Then have NO issues with the driveshaft fitting.



#2. In 1986 - Toyota made the rear-axle assembly 2 1/4" longer and the leaf-springs wider apart. So a 1990 axle will NOT line up with the springs on a 1983. That means you have to cut the spring perches off the 1990 full-floater and weld them back on closer together. Your 1983 probably has the springs on 37" center-to-center. The 1990 will be 39 1/4" center-to-center. If you do this - you have to make sure that the perches are welded on with exactly the same plane as before. This is so the angle of the differential pinion centerline is correct.



#3. In 1986 - Toyota increased the outer-diameter of the tubes in the rear axle assembly to increase weight-capacity. The 1983 tubes are likely 2 1/2" diameter. The 1990 tubes are 3 1/8" outer diameter. So, the old U-bolts from your 1983 will not fit. You have to buy new U-bolts or just get them made if you have a local auto-parts store that has a U-bolt bending machine.



#4. The bottom plates with four holes that mate with the U-bolts and also hold the shocks (at the bottoms) also will NOT work. You need the later plates for the later 3 1/8" OD axle tubes. Note that the later plates will not have shock absorber mounts that line up with your 1983. That is because the 1983 has non-staggered shocks that both mount in front of the rear axle. The 1990 has staggered shocks with one in front and one behind the rear axle. So you have to fabricate something. Two choices. Weld shock mounts to the newer plates and keep the old shock configuration. Or weld new shock mounts for the upper mounts on to the upper frame webs and convert to staggered shocks.



#5. A few added comments. The old parking-brake cables mate right up with the 1990 rear-axle. Also - on the subject of pinion flanges. Toyota changed the splines three times on the pinion gear so if you buy a new pinion flange it must match your splines. I think (but not sure) - Toyota changed from a coarse spline to a finer 27 spline in 1979. One way to tell, is IF you know your rear gear ratio. If it is a 4.11 then it is coarse spline. If it is 4.10, it is the finer 27 spline. 27 spline was used up to 2001.


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@jdemaris thanks so much for this info... How do you suggest mounting the sway bar?

I accidentally posted before done. I'll try again. Happens a lot to me recently. My grubby fingers don't work well with keyboards anymore.

#1. 1983 and 1990 trucks use the same universal joints. Same joints are used 1979-1995. So I assume the bolt pattern on your existing driveshaft flange will line up with the holes in the pinion flange on the 1990 rear-axle-assembly. But . . Toyota increased the size of the bolts in 1984 from 8 mm to 10 mm. So - at the least -you'll have to drill out the flange on your driveshaft so 10 mm bolts will fit. If it IS a different pattern - many places sell universal-fit pinion flanges. Unless you really know what you're doing - it is easy ruin a rear-axle by trying to change a pinion flange or seal. One addition note. You can just take the entire differential center-section from your semi-floater rear and stick it into the full-floater. Then have NO issues with the driveshaft fitting.

#2. In 1986 - Toyota made the rear-axle assembly 2 1/4" longer and the leaf-springs wider apart. So a 1990 axle will NOT line up with the springs on a 1983. That means you have to cut the spring perches off the 1990 full-floater and weld them back on closer together. Your 1983 probably has the springs on 37" center-to-center. The 1990 will be 39 1/4" center-to-center. If you do this - you have to make sure that the perches are welded on with exactly the same plane as before. This is so the angle of the differential pinion centerline is correct.

#3. In 1986 - Toyota increased the outer-diameter of the tubes in the rear axle assembly to increase weight-capacity. The 1983 tubes are likely 2 1/2" diameter. The 1990 tubes are 3 1/8" outer diameter. So, the old U-bolts from your 1983 will not fit. You have to buy new U-bolts or just get them made if you have a local auto-parts store that has a U-bolt bending machine.

#4. The bottom plates with four holes that mate with the U-bolts and also hold the shocks (at the bottoms) also will NOT work. You need the later plates for the later 3 1/8" OD axle tubes. Note that the later plates will not have shock absorber mounts that line up with your 1983. That is because the 1983 has non-staggered shocks that both mount in front of the rear axle. The 1990 has staggered shocks with one in front and one behind the rear axle. So you have to fabricate something. Two choices. Weld shock mounts to the newer plates and keep the old shock configuration. Or weld new shock mounts for the upper mounts on to the upper frame webs and convert to staggered shocks.

#5. A few added comments. The old parking-brake cables mate right up with the 1990 rear-axle. Also - on the subject of pinion flanges. Toyota changed the splines three times on the pinion gear so if you buy a new pinion flange it must match your splines. I think (but not sure) - Toyota changed from a coarse spline to a finer 27 spline in 1979. One way to tell, is IF you know your rear gear ratio. If it is a 4.11 then it is coarse spline. If it is 4.10, it is the finer 27 spline. 27 spline was used up to 2001.

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Mounting the sway bar means you need the links for each side and the upper link-brackets that need to be bolted or welded to the frame. I would NOT weld if it was mine. Welded destroys what is left of any rust-proofing on the inside of the frame where you cannot get to it to paint and promotes rust.

I found that since the Toyota frame is so thin - a good solid backing plate ought to be bolted to the frame. Then the link brackets onto the plates. Here are some photos of the last one I did (1987 full floater into a 1978 Toyota).

post-6578-0-55093000-1451156359_thumb.jp

post-6578-0-17219600-1451156361_thumb.jp

post-6578-0-75052700-1451156362_thumb.jp

post-6578-0-83361200-1451156363_thumb.jp

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Any preference on dif fluid?

Also I was thinking about putting a spacer/lift kit under there for a little more wheel clearance.. Any opinion on that?

@jdemaris thanks so much for this info... How do you suggest mounting the sway bar?

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Mounting the sway bar means you need the links for each side and the upper link-brackets that need to be bolted or welded to the frame. I would NOT weld if it was mine. Welded destroys what is left of any rust-proofing on the inside of the frame where you cannot get to it to paint and promotes rust.

I found that since the Toyota frame is so thin - a good solid backing plate ought to be bolted to the frame. Then the link brackets onto the plates. Here are some photos of the last one I did (1987 full floater into a 1978 Toyota).

I will be spraying the inside of my frame with Fluid Film, used to use motor oil but this appears to be a better option. Jim

http://www.fluid-film.com/

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Any preference on dif fluid?

Also I was thinking about putting a spacer/lift kit under there for a little more wheel clearance.. Any opinion on that?

Any oil rated GL5 will do the job just fine. If you run in very cold temps you might get an extremely small fuel-mileage gain by using a genuine synthetic 75W-90.

RE "spacer/lift kit." Where? Not between the axle and springs since that would lower it, not raise it. You certainly don't want to weaken the suspension by adding longer spring shackles. You could remount the rear axle under the springs and get a big raise in height. Or just add some air-bag "springs" between the rear axle and frame to jack it up like done OEM by several Toyota RV makers.

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In doing a little research I found that the 4x4 springs are SOA (like your suggestion Spring Over Axle) i am very interested in going this route even though mine is 2x4. I could use the clearance for adventures however would the front need to lift as well?

They are torsion bars up front right?

Basically how can I make mine look like this? http://www.pouringrain.co.nz/90_4x4_sunrader_004.JPG

I figure now is the time to do it if ever there was one.

Thanks again

Any oil rated GL5 will do the job just fine. If you run in very cold temps you might get an extremely small fuel-mileage gain by using a genuine synthetic 75W-90.

RE "spacer/lift kit." Where? Not between the axle and springs since that would lower it, not raise it. You certainly don't want to weaken the suspension by adding longer spring shackles. You could remount the rear axle under the springs and get a big raise in height. Or just add some air-bag "springs" between the rear axle and frame to jack it up like done OEM by several Toyota RV makers.

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So it looks as though I will have to have the ubolts and plate made as no parts stores around me have them (unless you can think of a better place to try) the info they need for the ubolts are...

"inside to inside"?

"length of rod"?

"Diameter"?

"Bend"?

Are you able to give me any of this? Just want to be sure cause they are about 70 bucks to have made :(

Mounting the sway bar means you need the links for each side and the upper link-brackets that need to be bolted or welded to the frame. I would NOT weld if it was mine. Welded destroys what is left of any rust-proofing on the inside of the frame where you cannot get to it to paint and promotes rust.

I found that since the Toyota frame is so thin - a good solid backing plate ought to be bolted to the frame. Then the link brackets onto the plates. Here are some photos of the last one I did (1987 full floater into a 1978 Toyota).

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So it looks as though I will have to have the ubolts and plate made as no parts stores around me have them (unless you can think of a better place to try) the info they need for the ubolts are...

"inside to inside"?

"length of rod"?

"Diameter"?

"Bend"?

Are you able to give me any of this? Just want to be sure cause they are about 70 bucks to have made :(

THAT is a pretty high price. A Carquest store near me has U-bolt bender. Last set with two new U-bolts, nuts and thick washers cost me around $25. ID of the U-bolt is the outer diameter of the new rear axle that is 3 1/8" OD (I already gave you that spec). You'll have to use 3 1/4" since 3 1/8" is an odd-ball metric size. Rod diameter is 9/16" but you can make it bigger at 5/8" if you prefer. Bend is round. Length is up to you. Depends on the thickness of your leaf-spring pack. Mine are 8 1/2" long with extra leafs and 2" to spare. Can't hurt if too long. Just cut off the excess. There are plenty of places on-line that sell pre-made U-bolts for $22 or less, total. $70 dollars is robbery. Either of these will work fine. If you choose grade 8 instead of grade 5 - you HAVE to use 5/8". 9/16" like OEM only comes in grade 5.

post-6578-0-55373200-1451415044_thumb.jp

post-6578-0-15716500-1451415047_thumb.jp

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Ok great! I got those bolts and almost all the parts I need. (Except for the plate the ubolts screw into)

I think my last devotion is if I go SOA? I really want more clearance.. Any suggestions on that? Even if it got me an inch or two. Would I have to raise the front if I did this?

THAT is a pretty high price. A Carquest store near me has U-bolt bender. Last set with two new U-bolts, nuts and thick washers cost me around $25. ID of the U-bolt is the outer diameter of the new rear axle that is 3 1/8" OD (I already gave you that spec). You'll have to use 3 1/4" since 3 1/8" is an odd-ball metric size. Rod diameter is 9/16" but you can make it bigger at 5/8" if you prefer. Bend is round. Length is up to you. Depends on the thickness of your leaf-spring pack. Mine are 8 1/2" long with extra leafs and 2" to spare. Can't hurt if too long. Just cut off the excess. There are plenty of places on-line that sell pre-made U-bolts for $22 or less, total. $70 dollars is robbery. Either of these will work fine. If you choose grade 8 instead of grade 5 - you HAVE to use 5/8". 9/16" like OEM only comes in grade 5.

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I suppose I don't need to go as high as the 4x4 any height would be ok with me. Have you seen this done at all. SOA? Without having to replace front parts?

I don't think you can adjust the front torsion system up high enough to match a 4x4 height in the back. Lots of members have been looking for more clearance but I've never seen an easy answer especially for the front

Linda S

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Ok great! I got those bolts and almost all the parts I need. (Except for the plate the ubolts screw into)

I think my last devotion is if I go SOA? I really want more clearance.. Any suggestions on that? Even if it got me an inch or two. Would I have to raise the front if I did this?

Get the original spring-arch back and you'll get plenty of lift, as it is. Jack up the rear a little just so the springs get the arch back in them and NOT with the wheels off the ground. Then see if that is enough height. I think you'll find it is plenty. To get it to stay that way -add some leafs to each pack.

Of course - another way is to just put on huge tires and a very high-number axle ratio to compensate.

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So it looks as though I will have to have the plate made

If you have the older shock mounts where both mount in front of the axle - Toyota never made any bottom plates to fit with the larger tubed rear-axle. One easy fix is to just get some later plates that are made for staggered shocks. Then take the old bottom shock mounts off the old plates and weld on to the new. That's how I did mine. Or - are you converting your rig to a staggered shock setup??

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I see U-bolt plates on-line to fit your Toyota for $11 each. No shock mounts on them since they are sold for axle-flips. If you want to keep your original shock mounts, these plates should work fine. Just cut off the shock mounts from your old plates and weld them onto these new ones. Like I did.

post-6578-0-04084000-1451516106_thumb.jp

post-6578-0-24893700-1451516117_thumb.jp

post-6578-0-32576000-1451516121_thumb.jp

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Mmm, spring over axle. Maybe that'd be my solution. I'm looking for more clearance for safer rough road excursions.

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I don't think you can adjust the front torsion system up high enough to match a 4x4 height in the back. Lots of members have been looking for more clearance but I've never seen an easy answer especially for the front

Linda S

From a good friend of mine who knows Toy trucks, especially 4x4s very well:

"You can only get at max 3-4in lift but that will also up the spring rate tremendously and you'll hate the ride. It's about a 10in lift to match a 83 4x4 ride height for a2wd.

I think you can get a pre runner setup though that lifts it pretty good via spindles."

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So I need new sway bar links. When the axle was taken off they cut one of the links. Toyota and parts stores around here keep telling me that they are discontinued... Anyone have any ideas?

I accidentally posted before done. I'll try again. Happens a lot to me recently. My grubby fingers don't work well with keyboards anymore.

#1. 1983 and 1990 trucks use the same universal joints. Same joints are used 1979-1995. So I assume the bolt pattern on your existing driveshaft flange will line up with the holes in the pinion flange on the 1990 rear-axle-assembly. But . . Toyota increased the size of the bolts in 1984 from 8 mm to 10 mm. So - at the least -you'll have to drill out the flange on your driveshaft so 10 mm bolts will fit. If it IS a different pattern - many places sell universal-fit pinion flanges. Unless you really know what you're doing - it is easy ruin a rear-axle by trying to change a pinion flange or seal. One addition note. You can just take the entire differential center-section from your semi-floater rear and stick it into the full-floater. Then have NO issues with the driveshaft fitting.

#2. In 1986 - Toyota made the rear-axle assembly 2 1/4" longer and the leaf-springs wider apart. So a 1990 axle will NOT line up with the springs on a 1983. That means you have to cut the spring perches off the 1990 full-floater and weld them back on closer together. Your 1983 probably has the springs on 37" center-to-center. The 1990 will be 39 1/4" center-to-center. If you do this - you have to make sure that the perches are welded on with exactly the same plane as before. This is so the angle of the differential pinion centerline is correct.

#3. In 1986 - Toyota increased the outer-diameter of the tubes in the rear axle assembly to increase weight-capacity. The 1983 tubes are likely 2 1/2" diameter. The 1990 tubes are 3 1/8" outer diameter. So, the old U-bolts from your 1983 will not fit. You have to buy new U-bolts or just get them made if you have a local auto-parts store that has a U-bolt bending machine.

#4. The bottom plates with four holes that mate with the U-bolts and also hold the shocks (at the bottoms) also will NOT work. You need the later plates for the later 3 1/8" OD axle tubes. Note that the later plates will not have shock absorber mounts that line up with your 1983. That is because the 1983 has non-staggered shocks that both mount in front of the rear axle. The 1990 has staggered shocks with one in front and one behind the rear axle. So you have to fabricate something. Two choices. Weld shock mounts to the newer plates and keep the old shock configuration. Or weld new shock mounts for the upper mounts on to the upper frame webs and convert to staggered shocks.

#5. A few added comments. The old parking-brake cables mate right up with the 1990 rear-axle. Also - on the subject of pinion flanges. Toyota changed the splines three times on the pinion gear so if you buy a new pinion flange it must match your splines. I think (but not sure) - Toyota changed from a coarse spline to a finer 27 spline in 1979. One way to tell, is IF you know your rear gear ratio. If it is a 4.11 then it is coarse spline. If it is 4.10, it is the finer 27 spline. 27 spline was used up to 2001.

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So I need new sway bar links. When the axle was taken off they cut one of the links. Toyota and parts stores around here keep telling me that they are discontinued... Anyone have any ideas?

Yes. Just make them. Not a huge project. The original links are around 11/16" OD steel, or 17-18 mm. Two bends, so three straight sections - 2" X 2" X 4". 4" part with the 3/8" or 9-10 mm threads. Then make a U-shaped bracket to weld on to the non-threaded end with a 3/8" hole and 7/8" of space inside to slip over the end of the stabilizer bar. The bar itself - where it attaches to the rear axle via the rubber mounts is 23 mm in diameter. A grade 8, 8" long 5/8" bolt with fine threads would likely work fine. Just heat with a torch and bend where needed. Then weld the U-bracket on the end. If you want smaller threads at the end, cut off weld on a smaller bolt.

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