The way 620s drive. Frame twist?

[Willdatsun]

So I am having my first driving experience of a 620. Its a 76 KC. I'm used to tons of old Datsuns and they all drive pretty well but this 620 really is a boneshaker. Feels floppy. When you hit some potholes and bumps it feels like the whole truck sort of oscillates, like a sort of torsional spring, like.. scuttle shake. The passenger bucket seat shakes. Is that normal? Do they all do it? Am i making any sense? Drives ok on smooth roads but steering seems to pull to one side a bit and is a little on the heavy side. Almost like too much caster, has anyone experimented with shimming the top pivot to change the caster?

 

Do short wheelbase 620s drive better?

 

Thanks!

[metalmonkey47]

Never driven a KC 620, but I'd say this probably isn't normal.

 

 

My 620 is pretty smooth for the most part.

[I'm BLUE]

Check your shocks

[datzenmike]

620s have a boxed frame which is very strong and rigid. My old frame was severely rusty and rotting away which takes away the strength. Think of a square tube and try twisting it... very difficult to do. Now imagine a C shape with one side open ... it will twist very easily, and this is what was happening on mine.

 

It's a truck, so built mostly for carrying loads and not so much for comfort. The torsion bars and rear leaf springs will be firm. Tires are another thing that can stiffen or soften a ride. Tires are part of the suspension system and have lots of 'give'. Nylon tires are firmer than good radials. Even some radials are firmer or softer than others. Running at the lowest recommended safe tire pressure will soften the ride. Replace the shocks... these are likely the biggest cause of a harsh ride.

 

Caster is designed in at the factory and optimal for the truck. Increased castor will make the steering wheel return to center faster when finishing a turn. High speed is more stable but there is an increase in effort to turn the wheel. I wouldn't mess with it unless there has been damage that needs correcting.

 

Perhaps you are thinking of camber. This is the tipping in or out of the top of the tire. Again this is set at the factory and shouldn't need changing unless the ride height has been changed.

 

Toe is the turning in or out of the wheels as viewed from the front.

 

 

Do short wheelbase 620s drive better?

 

Thanks!

 

In my experience the longer the wheelbase the smoother the ride.

[Stupid_fast]

align it, replace shocks, rusted leaf springs ? rotted bushings ?

 

Passenger seat bolts loose? If frame is bent 90% of the time its extremely easy to tell, you can see where panels are not aligned properly.

 

 

edit, aaand two people beat me to it. :)

[Willdatsun]

Hi no I was thinking reduce caster as it may lighten the steering. It feels like too much trying to return to centre. Frame is solid and truck has no damage. Even the paint is original.

 

The shocks seem pretty good (bouncing the truck it doesn't keep bouncing, just comes back up once. ) Only sensation similar I have experienced is in a Mopar C body convertible, when one wheel hits a bump.

 

I currently have 185 60R14 tyres up front which could use being a little taller.

 

Thanks for the replies.

 

Might try the truck with a bunch of weight in the back.

[Sealik]

I would take it in to an alignment shop.....get them to check it out.

Here....I can take a vehicle in and get them to go over it and tell me what's wrong before they do any work.

Sooooo...I can take it home, fix the issues....and eventually head back for an alignment...maybe... :sneaky:

 

Which I'll be doing in the next few days :D

[Eagle_Adam]

youve been here long enough man! where the pics!!!! :P

 

ive driven long beds, KC's, and I DD a standard cab. What you are describing is not normal.

Check the shocks and bushings to start with.

 

 

 

Hell put it up on ur fork lift and take a look see ;)

 

 

 

 

 

now, i will patiently wait for Pics...............

[datzenmike]

Grease the king pins. I had a 521 and the pins get seized and are hard to steer.

[]2eDeYe]

youve been here long enough man! where the pics!!!! :P

 

ive driven long beds, KC's, and I DD a standard cab. What you are describing is not normal.

Check the shocks and bushings to start with.

 

 

 

Hell put it up on ur fork lift and take a look see ;)

 

 

 

 

 

now, i will patiently wait for Pics...............

 

Lot's of pics in his thread in the 620 section ;)

[Eagle_Adam]

2eDeYe' timestamp='1347550718' post='756556']

 

 

Lot's of pics in his thread in the 620 section ;)

 

but that requires effort :rofl:

[Suspect]

even on the rustiest 620 I've drove, it still drove good down the road. My 77 Kc rides excellent, way better than any s-10 or ranger I've drove. 620's are real firm in the back, they have a thick leaf spring that some people take out to make it ride a little better in the back.

 

my 74 with torsion bars removed drives better than you are describing

[Willdatsun]

Ok thanks

 

[banzai510(hainz)]

76 dont have kingpins

 

Lift it up and feel if one side is tighter ,then grease it.

ck the steering box if soemone set it to tight.

ck wheel drag. bearings?

 

OH Eagle Adam

He had posted photos already from the trailer is towed it home with.

[]2eDeYe]

76 dont have kingpins

 

 

?? :confused: