Spring compressor

[Gary Waugh]

I also borrowed a spring compressor from O'riley, it looked brand new and worked a treat, I was surprised that they don't charge a rental fee!! the springs need quite some force to compress (I guess the expedition is a heavy old girl so needs stiff springs!). Took me about 3 hours to change all 4 shocks, i was surprised that I got the tracking checked afterwards and it needed adjustment, as I hadn't undone any of the steering joints, I had assumed nothing would need adjustment!! Maybe it was out before I changed the shocks, but I would suggest getting the tracking checked after you change the shocks.

Gary

 

[07navi]

I also borrowed a spring compressor from O'riley, it looked brand new and worked a treat, I was surprised that they don't charge a rental fee!! the springs need quite some force to compress (I guess the expedition is a heavy old girl so needs stiff springs!). Took me about 3 hours to change all 4 shocks, i was surprised that I got the tracking checked afterwards and it needed adjustment, as I hadn't undone any of the steering joints, I had assumed nothing would need adjustment!! Maybe it was out before I changed the shocks, but I would suggest getting the tracking checked after you change the shocks.

Gary

We have an O'reillys in this little town also thankfully. I think your front end was out before you worked on it but it's all good now.

 

[Vancouver Bob]

What does better springs have to do with larger tires?

Probably nothing... but my logic was heavier tires, more force against the springs when hitting bumps. Same reason I want a firmer shock.

 

[07navi]

Probably nothing... but my logic was heavier tires, more force against the springs when hitting bumps. Same reason I want a firmer shock.

No more force from bigger tires, the force comes from the bump, plus firmer shocks will just jar you more. You have that all backwards.

 

[Vancouver Bob]

No more force from bigger tires, the force comes from the bump, plus firmer shocks will just jar you more. You have that all backwards.

F=Ma... bigger the mass, bigger the bump, bigger the force

 

[Vancouver Bob]

F=Ma... bigger the mass, bigger the bump, bigger the force

Plus I added a new bumper up front so I increased load on the springs... front ones anyways.

 

[07navi]

F=Ma... bigger the mass, bigger the bump, bigger the force

The force comes from the weight of the vehicle pushing down and then rebounding with a given spring pressure, and the tire size and weight doesn't enter into that. Your analogy sounds good but not true.

 

[Robert McMillan]

F=Ma... bigger the mass, bigger the bump, bigger the force

Force on spring is acting in a downward vector, from the weight directly on top of the spring perch

 

[mjp2]

Plus I added a new bumper up front so I increased load on the springs... front ones anyways.

View attachment 37359

Seriously nice job on that bumper paint job. Really flows with the truck and minimizes the underbite look that a lot of the offroad bumpers have on our rigs.

 

[Vancouver Bob]

Force on spring is acting in a downward vector, from the weight directly on top of the spring perch

Very true. There's also an upward force from the road to the tire thru the lower control arm and eventually thru the strut perch. Spring isn't moving so sum of the forces must equal zero. When you're driving along and hit a bump in the road the tire bounces up, strut pushes up against the bottom of the spring, spring compresses, top hat holds the top of the spring in place, opposing forces must eventually equalize zero again. I'm just saying with a heavier tire that upward force is going to increase.