Truck veers slightly

Dealing with all subsystems specific to the diesel powered Datsun-Nissan 720 pickup trucks.

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cseger1
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Joined: 17 years ago
Location: Houston TX

Truck veers slightly

#1

Post by cseger1 »

Hey folks,

I have had 10,000 trouble free miles since my last post and I'd like to thank everyone that helped me get back on the road. Especially Al for giving me the ability to drive in the rain :D .

My question today is about the cause of my wierd steering problem. When I am running at a constant speed the truck veers slightly to the left and I have a little pressure on the wheel to cancel this. As soon as I let up on the throttle the truck veers to the right and I have to steer left. Maybe I have that backwards, now that I've written it out, I can't remember for sure. Is there a fix for this?

Thanks,

Christian
Christian
1981 720 SD22
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asavage
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Re: Truck veers slightly

#2

Post by asavage »

If it pulls fairly constantly in one direction, swap tires side to side and see if the symptom changes.

But if application of power really does change the pull, look for loose suspension mounting points (A-arms, crossmember bolts), cracked frame, or loose rear axle mounting points.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.
cseger1
Posts: 122
Joined: 17 years ago
Location: Houston TX

#3

Post by cseger1 »

It is a slight veer to either side but when I lay off the power the shift from one side to the other is very pronounced. It feels like a single large wiggle. Like the rear end shifts over to the other side.
Christian
1981 720 SD22
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Knucklehead
Posts: 148
Joined: 18 years ago
Location: Phoenix

#4

Post by Knucklehead »

In that case you better check the U-bolts and shackles on the rear.
'82 standard cab 3 axle SD22 turbo
'89 int'l 9700 Cummins 444 (855 ci)
'29 HD FD export model
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philip
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Location: Southern California, USA

Re: Truck veers slightly

#5

Post by philip »

cseger1 wrote:-SNIP- My question today is about the cause of my wierd steering problem. When I am running at a constant speed the truck veers slightly to the left and I have a little pressure on the wheel to cancel this. As soon as I let up on the throttle the truck veers to the right and I have to steer left. Maybe I have that backwards, now that I've written it out, I can't remember for sure. Is there a fix for this?

Thanks,

Christian
Only because you noted "Maybe I have that backward", I'll mention ONLY about "veering."

You can have the truck's steering alignmet performed so that the CASTER, Toe-in/out, and thrust are .... correct (see in FSM page FA-25).

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Now let's talk about CAMBER. Both camber shall be equal. IF they are not, then the truck will "veer" as directed. For example on flat straight highway, let's say the left tire has 0° camber while the right tire is (negative) 0. 6°-. The truck will "veer" (for this I would say "wander") to the left.

Image

Bottom line is; the alignment setting to achieve equal camber is more important than equal caster (assuming left vs. right caster degrees are not hugely unbalanced).
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"
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asavage
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#6

Post by asavage »

All good information, but if the veering changes with accel/decel, the veering is not caused by an alignment issue per se. Loose or worn parts which dynamically change the alignment is the cause.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.
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philip
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Posts: 1494
Joined: 18 years ago
Location: Southern California, USA

#7

Post by philip »

asavage wrote:All good information, but if the veering changes with accel/decel, the veering is not caused by an alignment issue per se. Loose or worn parts which dynamically change the alignment is the cause.
Sometimes I am a minor deity ... while you are a minor "diety" :wink:

Without loose or worn parts or misalignment but ... having "setback" can bring about this slight "veer" response due to bent parts. That said, the prima facia suggests one or more sloppy rubber bushings found in a-arms, tension rods, idler arm, leaf springs or, metal components like ball joints, frame crack, and leaf springs shifting. :wink: Of course there -could- be an off-the-wall reason. :wink:

Maybe the 'member' should just install an automatic transmission which should soften accelerate / decelerate rates imposed on the suspension. :wink:
Image
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"
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asavage
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#8

Post by asavage »

Setback would not be affected by accel/decel. There is a worn part (sloppy, not just bent or mis-aligned), or loose part.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.
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Knucklehead
Posts: 148
Joined: 18 years ago
Location: Phoenix

#9

Post by Knucklehead »

Does cseger1 have an update for us? It has been 6 months. Something about actuality that just makes me warm and fuzzy. Yes, feedback just makes it all worthwhile doesn't it?
'82 standard cab 3 axle SD22 turbo
'89 int'l 9700 Cummins 444 (855 ci)
'29 HD FD export model
cseger1
Posts: 122
Joined: 17 years ago
Location: Houston TX

#10

Post by cseger1 »

Knucklehead wrote:Does cseger1 have an update for us? It has been 6 months. Something about actuality that just makes me warm and fuzzy. Yes, feedback just makes it all worthwhile doesn't it?
So sorry for letting it go this long. The truck has been running well and my wife and I are starting a small business. Its kept me away....

Anyway, the truck's rear end is not stock. I am not sure what the springs came off of but it sits way up in the rear. I put 4" lowering blocks on it to smooth out the looks. At first all was well but then the problem I described came up. In an effort to deduce the cause I removed the blocks. Problem gone. So now the dynamic veering is gone and the tail pokes up.
Christian
1981 720 SD22
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