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swapping ball joint front en on my 74 620


Thorpeado

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Hello Ratsun members, I have a 1974 620 pickup that is my daily driver. My question is this, the truck has been lowered a lot by the previous owner and it has beat up the old king pins tie rod ends etc. quite a lot and now there is a bit of play in the front end, so I have heard that it is possible to swap the ball joint front end off of later model dat suns or possibly a hardbody. I like the idea of this rather than dealing with rebuilding the old king pins. I would like to keep the truck lowered as well, are there aftermarket lower profile bumpers that allow for a little more suspension travel? any help would be great as far as years of trucks that will work for a swap. Sorry for no pictures, I haven't  taken any of the truck but will try to soon.

 

- cheers

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If you look at a later 620 frame, you can see the upper control arm mount is rotated back slightly.  In other words, it's not built the same so all the later parts don't necessarily align.  They will bolt up, but the upper control arm will be about an inch to short. 

 

You have a couple of options.  Change the frame to either the later 620/early 720 or get a set of custom upper control arms.  I made my own, a user by the name of Beebani makes some.  My gripe with Beebani's design is there is no tilt added to the ball joint.  If you look at the lower control arm it has about 20 degrees of tilt.  The stock upper control arm also has about the same amount of tilt.  Beebani's has no tilt, so  you lose over 70% of your ball joint range (30 degrees is a typical ball joint tilt range).  Is it that critical?  I don't know.  I haven't ran the control up and down in its range to see how far the ball joint actually rocks.

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If you look at a later 620 frame, you can see the upper control arm mount is rotated back slightly.  In other words, it's not built the same so all the later parts don't necessarily align.  They will bolt up, but the upper control arm will be about an inch to short. 

 

You have a couple of options.  Change the frame to either the later 620/early 720 or get a set of custom upper control arms.  I made my own, a user by the name of Beebani makes some.  My gripe with Beebani's design is there is no tilt added to the ball joint.  If you look at the lower control arm it has about 20 degrees of tilt.  The stock upper control arm also has about the same amount of tilt.  Beebani's has no tilt, so  you lose over 70% of your ball joint range (30 degrees is a typical ball joint tilt range).  Is it that critical?  I don't know.  I haven't ran the control up and down in its range to see how far the ball joint actually rocks.

 

That's not what this guy says...

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OK, let us understand something here about this link you provided, this guy bagged that truck, he has no way to properly align his truck, he has negative camber in ample supply, and he likely wants his front tires to tuck into the fender wells when dropped, so it worked out perfect for him.

This may be a bolt on, but it's not alignable unless the upper control arms are lengthened.

Drilling out the upper control arm mount holes and tapping them to the 720 bolt size is smart, very smart, also using early 720 lower control arm bushings is also smart, as one doesn't have to add washers to take up the slop, but the upper control arms are about 5/8ths of an inch short to be able to have it properly aligned on a stock height or slightly dropped truck.

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I missed that that guy bagged his truck. 

 

Touche'. 

Don't take me wrong, that guy did a lot of things right, and it worked for what he was doing to the truck.

I get kinda touchy on this subject, I did all this back in about 2005, and I did not figure everything out right away, it was kinda scary for a while, and until a couple years ago I had issues, so when I read incomplete instructions that don't cover everything, I go crazy.

You should have seen the complete reply I wrote, talk about rants. :lol:

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Thanks guys for the tips guys, from what it sounds like upgrading the upper control arms to beebani's might be the way to go and using 720 lower arms and hardbody spindles with disc brakes might work out the best. I assume that I would need to get the booster and master cylinder from the same truck to supply ample braking. The truck now has been converted to disk brakes up front using the honda passport conversion, however it requires a lot of pedal pressure so I'm guessing the previous owner did not upgrade the master cylinder and booster. I will PM beebani and find out whether the ball joint angle is within tolerances. heres some pics of  the lil' datsy

 

IMG_9973_zpsb19435ad.jpg

IMG_9975_zps51829c36.jpg

IMG_9974_zpsedbfd6ac.jpg

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I missed that that guy bagged his truck. 

 

Touche'.

 

 

Bagged indeed! My camber is actually correct at ride height, but that's because I cut and bent the upper arm towers. Not the thing to do if you're not comfortable with it. Purchase or build adjustable upper arms. All else should work well.

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Thanks guys for the tips guys, from what it sounds like upgrading the upper control arms to beebani's might be the way to go and using 720 lower arms and hardbody spindles with disc brakes might work out the best. I assume that I would need to get the booster and master cylinder from the same truck to supply ample braking. The truck now has been converted to disk brakes up front using the honda passport conversion, however it requires a lot of pedal pressure so I'm guessing the previous owner did not upgrade the master cylinder and booster. I will PM beebani and find out whether the ball joint angle is within tolerances. heres some pics of  the lil' datsy

 

IMG_9973_zpsb19435ad.jpg

IMG_9975_zps51829c36.jpg

IMG_9974_zpsedbfd6ac.jpg

 

Truck look good man! Keep us updated with pics of the suspension upgrade. I'm in the process of deciding to lower and modify the suspension on my truck too.

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ahh im looking at converting mine within the year also and was almost given a pair of hardbody drop spindles a couple weeks ago and turned them down haha i believe they were drop spindles tho...what year hardbody spindles are yall thinking of?i have a 77 kingpin and im gonna be swapping to discs soon!

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This is the combo I found that looks like it's going to work.  I have and 83 hub, 83 caliper and an 86 rotor.

 

Note the spacing difference with the 83 rotor.  There's about a quarter inch gap between the caliper and the drop spindle.  This is remedied by using the 86 rotor.

 

aOpUjV.jpg

 

Just for reference I put a picture of three different rotors.  From left to right 83, 86 and 82.  The hubs for the 83 will bolt on to the 86 rotor.  The added height makes up the difference in the previous picture.

 

i9R1RM.jpg

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  • 7 years later...

Super old thread.....sorry.  If anyone else comes across is like I did.......the reason for the gap and having to use the '86 rotor is because of the dropped spindles.  All dropped spindles are Hardbody units. When you buy them new, you'll probably get the spacers that go in that gap. They allow the 720 rotor to be used so they can sell the spindles as 720/HB units.  There's no advantage to using the 720 rotor with the spacers.....in fact, it makes wheel fitment a lot harder.  Just use the HB rotor with no spacers on the dropped spindles.  The calipers are the same and the hubs are very similar....the nose diameter for the center hole on the rim is the only difference.  

 

Okay......it can go back into hibernation again. :)

 

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