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620 pickup camber!?


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just bort a 620 pickup and it has a huge amount of -camber, the lower arms look std but the upper arms dont look right as the bumpstop hits in a weird spot, any ideas on what upper arms these might be and what the best way to identify propper upper arms is?

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I hate to jack this thread, but I can relate.....


I got a '78 620 single cab, short bed. Ball joint front end. It's pretty low.... i'd say approximately only 3/4" (That's just under 2 cm for you, Mike  :angel: ) gap between front fender and tire. 


I'm running 15x8.5 with 195/65/15 and have SERIOUS bump steer issues! Is there a way to correct this terrible bump steer without lifting it back up? I haven't thrown it on the alignment rack at work yet, but i'd be willing to bet it's at 4+ negative degrees of camber. Toe is out too. Can toe cause bump steer? 



To help answer OP's question, the camber is caused from lower the vehicle. The way we lower the front end on the 620 is by loosening the torsion bars and literally sagging the weight of the vehicle. It just so happens that the camber adjustment is made on these torsion bars. Therefore, height will be affected when adjusting camber. Example, lift the front and you'll have serious positive camber issues, and visa versa with lowering the front.


I do think you can lower the front end with drop spindles only if you're 620 has balljoint suspension; post 1977.

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Ideally the steering box Pittman arm, cross rod, idler arm and tie rods should be in the same level plain. A bump or dip in the road will swing the outer end of the tie rods up and down in a small arc and there isn't much change in it's side to side length. BUT if you lower (or raise) for example, the tie rod ends tilt upward (or down) and through an arc becoming shorter in a side to side width. This will pull the fronts of the tires inward causing toe in. You can adjust this out so it steers straight but when hitting a bump (say on the right side only) the arc the tie rod end travels through is much more pronounced, shortening the side to side length, pulling the right tire in and it toes in severely (though briefly) and the truck veers to the left side.


Ideally the upper and lower control arms also are designed to operate best in one position. The lower control arm (LCA) is longer than the top arm and when the body is lowered or raised, the top travels through a shorter arc than the bottom one and pulls the tire inward at the top producing negative camber. A small amount can be removed by adjusting the shims but like the steering, the already angled upper control arm produces much more than when at it's proper ride height. A lowered or raised truck even though aligned will wear the tires more than one at the correct ride height. It's the camber equivalent of bump steer.

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Wow, Thanks for the thorough explanation. I have all new components for the front end ordered from Rock Auto but they sent me two right-handed thread inner tie rods in stead of a left and a right hand threaded tie rods (that bolt to the center link). I'll do an alignment on it after I receive my correct left / inner tie rod.


Speaking of tire wear, i've chewed through 6/32" in only 1,800 miles. Yes, that's 3/5ths of a new tire's tread in a mere 1,800 miles. Luckily, and the only reason why I run these tires, I work at Toyota so I can utilize used tires from customer's Priuses (195/65/15) so I'm not concerned about the wear ... until it persist after components are replaced and the alignment is done.

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Toe in is the worst for scrubbing rubber away. Additionally the two tires are fighting each other and normally it roughly equal and not too noticeable. Watch out in the rain! Hit a deep enough puddle with the left tire and it aqua planes and looses traction, the right is toed in and the truck will jump into the other lane. My 620 came to me this way from a botched toe in. Also when turning tight like into a driveway the wheel will actually start turning into the turn by itself.


I went across the street and took a good look at my front tires. They were both pointing directly at me!

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You get camber back by removing (on the early 620) or adding (later 620) shims to the upper a-arm. You can also adjust caster a bit this way by adding more or less shims to the front or rear mounting bolts.



Why you wouldn't get an alignment after lowering your vehicle is beyond me. Either pay for the alignment or pay for new tires, your choice I guess but I would choose alignment. 

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I just got the truck about a month ago. PO lowered it and didn't get an alignment. I get free used tires at work so I don't mind... For now. I have (almost) everything to rebuild the front suspension. Instead of doing an alignment now and potentially break something by reeding on it, I'll wait til I replace everything. There aren't boots on the tie rods, hence te reason in afraid I'll actually break them while trying to bust em loose.

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You're definitely right about that! Dragging tires around will most definitely cause more damage than wrenching on them and potentially breaking something.


I'm just waiting to receive my other inner tie rod and then replacing all front end parts and doing an alignment. Just the waiting game for parts in the mail at this point.


No sense in doing an alignment now and then then redoing in a week and a half. ...... Well maybe there is, but I'm just lazy I guess, There's my excuse. lol.

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