Unstable on the highway

[PopFly]

I have a 1990 pathfinder. I bought it used a year ago, did a little maintenance which included a new pair of good Monroe shocks and took off on a 2 1/2 week, 3500 mile, camping trip to New Brunswick with my fiancee and two teenaged kids. It was a wonderful trip I highly recommend it. The truck performed very well and has continued to do so ever since except for one thing; it is very unstable at highway speeds.

 

Anytime I am cruising and let off the gas, releasing the torque off the rear end, the back of the truck sways a lot. In a straight line it sometimes slowly rocks side to side. When I am going around a long turn at speed the truck sways too. In fact in this situation I am afraid to brake or vary my turn radius (like to switch a lane). It's a bit scary. I have looked at all the shocks, they are good; stabilizers are good and the springs and torsion bars are okay too. When I bounce the truck manually it recovers quickly although the springs seem to have quite a bit of travel. I am beginning to wonder if it's not the tires having just too much give in the sidewalls because if I push sideways at the rear of the vehicle I notice I am able to flex them a bit which seems odd. The tires are Firestone Firehawk R4S 31x10.5x15LT.

 

Any advice is greatly appreciated

[Precise1]

Tire wear and pressure could have something to do with it, but I would check all the bushings, especially the pan hard rod's. Unfortunately, some of the bushings are hard to check without disassembly/removing them. I'm sure others will have additional suggestions, but I fear you have a sloppy rear end my friend...

How many miles on the vehicle ? Do you live in salt country ?? Hows the front end also, that can magnify things also.

Congrats on the camping trip. I've been on a few like that and cherish them as life memories.

 

B

[FLApathy]

make sure your tires have the right psi in an suv it should be about 35, 32 in a car,

and then what b said, oh and make sure your tires have not been recalled, im not sure what the firstone deal is now but most of the time one gave out was due to under inflating

[headpeace]

by stabilizer do you mean sway bars? rear sway something you could possibly check, thats all I know

[Mookie]

In addition to what the others have said, have a peek at your upper and lower link arms. Worn bushings in those can cause swaying.

In the newer Pathys this is a common problem, not as much with our WD-21s.

[denisb]

Same problem with mine and Mookie is right. My vote is for control arm bushings. This effect will be increased with weight.

 

Not that I would know, but lets say you were to have 4 people in the truck, be passing a Transport truck and hit a bump, you would probably find it quite harry.

 

I bought them , just haven't replaced them yet. I guess it could be called pro......procrasti......ah, I'll look up that word in the dictionnary later

 

Denis

[PopFly]

Thanks for all the responses!

 

The truck has about 115,000 miles on it. When I bought it a year ago there were about 95,000. It appeared to have been recently revitalized after sitting for quite some time.

 

I live a few miles west of Detroit. Not that many people know it but Southwest Detroit sits atop a huge salt mine. In winter it's slung on the roads in excess. So yes, in a way I do live in a salty environment. Perhaps one of the worst.

 

I am not sure about the recall status on the tires but I will check that ASAP. My inflation is good.

 

Yes, I did mean sway bar bushings when I said stabilizer bushings. There is some cracking on them but nothing I would have expected would cause the kind of drivability issues I'm having. I am not sure what "pan hard rods" bushings are. As far as the front end I am not too sure about the ball joints. They are original and have no zirc fittings so they may need changing. Aside from that the front end looks good. There is no cupped wear on any of the tires.

 

I will start by reinspecting all my bushings, especially the control arm bushings, more carefully and replacing any that are the least bit suspect. That is after checking on the tire recall.

 

By the way, my clutch pedal is very spongy near the top of it's travel. It seems to disengage well and I get a good response when it grabs, never any slipping, noise, smell or anything. It makes sense that it's wearing out but somehow it "feels" like the clutch is okay and the problem lies elsewhere; like in one of the cyliders or perhaps a worn or bent shift fork. Somebody told me it acted like it was the slave cylinder. That seems unlikly but I thought I'd ask.

 

Thank You,

John

[Vsicks Pathy]

Mookie is correct. The problem lays in your front end (steering). The Pathy will spit out front end components pretty quickly if you are going off road. This piticular problem sounds like your drag link has sh!t itself. Is it worse on corners? When the drag link STARTS to fail it can change your front end 'toe' up to 5 degrees as the car travels over the slightest undulations in the road. I know it can make for some scarey moments first hand. I used to get the 'death' wobbles bad going around corners.

[Guest peeny420]

I just towed with my pathy for the first time and noticed that I would get a wobble when I was going down hill and hit a bump or got a large crosswind. Do you guys think this could be caused by the same thing?

[iLLlegal]

hmm ya I wobble when ever I have to break fast at a stop light or somethin and it just goes all over the place...dunno if thats the same thing but I might check it out.