How much does your rear end move down when you stand on the bumper? (Trying to diagnose harsh ride.)

[2004mountaineers]

How much does your rear end move down when you stand on the bumper? I just stood on mine, and it barely moved 0.25inches and I weigh 190pounds. In contrast, my Grand Cherokee moves very easily with just one hand... I am presently trying to diagnose a very rough ride on the below Mercury. (Presently the tires have 27psi in them.)

2004 Mercury Mountaineer, 4liter, v6, 'awd'.

 

[Mbrooks420]

That’s not enough air in those tires. I don’t care what the ride is like, it’s negligent to run that little air in your tires. You are a danger to everyone on the road.

The only thing that tells you is your spring rate. If you want it to sag more, get softer springs.

Blow those tires up to whatever it says on the door card.

 

[2004mountaineers]

That’s not enough air in those tires. I don’t care what the ride is like, it’s negligent to run that little air in your tires. You are a danger to everyone on the road.

The only thing that tells you is your spring rate. If you want it to sag more, get softer springs.

Blow those tires up to whatever it says on the door card.

Is a quarter-inch normal though for 190pounds ? Could the shock be seized or something else seized ?

 

[Mbrooks420]

I can’t say, I’ve never had a 3rd Gen.

What kind of tires do you have?

 

[2004mountaineers]

I can’t say, I’ve never had a 3rd Gen.

What kind of tires do you have?

Tires are P235-70-R16 M+S
I have included some pictures of the rear-suspension while I was out there.

https://imgdump5.novarata.net/dx85ap.jpg

https://imgdump5.novarata.net/8ah1ep.jpg

https://imgdump5.novarata.net/uwkcdw.jpg

https://imgdump5.novarata.net/e4n2rd.jpg

https://imgdump5.novarata.net/6fuxex.jpg

 

[Mbrooks420]

Typically a P radial will ride nicer than an LT or AT tire. I’d assume the struts would need replaced if they’re still factory. You might want to look up the spring code on your door and see if you can get a softer set.

Preassembled struts are a gamble as far as the spring rate.

 

[Mbrooks420]

It looks like MOOG sells a variable rate spring for these. That would likely ride better, without sacrificing all the capacity.

 

[J_C]

Struts don't normally seize, but then vehicles don't normally have their rear end get tighter over time either.

I might find a speed bump somewhere, and let the rear end have a jolt or two. *Not my fault if you break something that might be broken anyway*. At the same time, I agree with Mbrooks that if those are the original struts, they're likey due to be replaced but if it is your spring rate at issue, that won't soften the ride.

Maybe instead of the speed bump idea, just pile ~400lbs worth of cargo in and stand on the bumper. If it doesn't sag more than 1/4" you know something is wrong like seized strut, or if it unseizes you'd have a sudden drop.

 

[LMHmedchem]

If you have a hydraulic floor jack you could jack up, put in your jack stands, and remove one of the rear tires. Then move the jack to under the control arm where the strut bolts in. Use the jack to lift the lower control arm and watch the strut. If the strut rod shortens as you lift then it isn't frozen. If only the spring compresses and the strut rod remains the same length then you know what the issue is.

You probably have to do both sides to be sure. If it is frozen, you might be able to free it up with the jack in the same way but it would need replacing.

It seems more likely that the strut has collapsed from loss of compression than frozen. Is your rear end riding low as far as you can tell?
Do you go for long periods of time without driving it?

LMHmedchem

 

[Fix4Dirt]

at least this 2g standing on it badly makes a dent in the height, im 150 and i gotta jump to get it to really move any notable amount, and even then it isnt much. now with a few hundred pounds of weight and 4 bikes on the hitch then it sags an inch or inch and a half iirc.

 

[TechGuru]

You need to run all 4 tires at 35psi minimum on these vehicles.

3rd gen explorers ride like a 3/4 - 1 ton truck. They're stiff springs on purpose to prevent rollovers. Ford was extra cautions after all the 2nd gen law suits.

If you want a smooth ride look into a aftermarket kit to replace your springs with airbags.
(Anyone know if the airbag suspension out of a Lincoln Navigator would fit?)

 

[J_C]

I just had a crazy idea. It'll cost a little in gas but nothing in parts or labor.

Put a few hundred lbs in the back, and drive around with it for 1000K mi. Not only will this cause the rear to be less busy for that 1000K, but once you take the load out, the suspension should have settled a bit and not be as jittery.

If you do that, you definitely want every bit of 35PSI in the rear tires. With P235's, I'd go closer to 40PSI, then drop back down to 35PSI once the load is removed. This assumes they are rated for 40PSI if not more. Do not exceed max inflation rating on the sidewall.

 

[TechGuru]

I just had a crazy idea. It'll cost a little in gas but nothing in parts or labor.

Put a few hundred lbs in the back, and drive around with it for 1000K mi. Not only will this cause the rear to be less busy for that 1000K, but once you take the load out, the suspension should have settled a bit and not be as jittery.

If you do that, you definitely want every bit of 35PSI in the rear tires. With P235's, I'd go closer to 40PSI, then drop back down to 35PSI once the load is removed. This assumes they are rated for 40PSI if not more. Do not exceed max inflation rating on the sidewall.

Most say 44psi max on the sidewall.