Van Pogo-ing...

[Theshwed]

Hey all - i've recently been troubleshooting some issues on my 2002 Ford E350 Quigley. I've been making one chnage at a time to identfy some driving issues. The most recent issue is the feeling of the van pogo-ing/bucking like a horse. It happens distinctly in two driving conditions.
1. When i stop. Doesnt matter if its a hard stop or light stop. I get 5-6 oscillations front to back before it settles to a stop.
2. Above 60mph. At this speed its a constant undulation up and down.
The change that made this noticeable was tires. I switched from BALD bfg ta ko2 to hankook dynapro atm, both in 285 75 16 E.

So... any thoughts on if tires can actually be the culprit, or is it just letting a symptom shine?

 

[brianjwilson]

Worn out or improperly valves shocks. Speak to Agile Offroad.

 

[Theshwed]

Thats one of the previous changes. To be reviewed at a later date. For now im giving them the benefit of the doubt and ruling it out as a root cause.

 

[Herbie]

Thats one of the previous changes. To be reviewed at a later date. For now im giving them the benefit of the doubt and ruling it out as a root cause.
View attachment 459550

I wouldn't. Anything more than 1.5 strokes on the suspension from a single input (like braking) means the suspension is under-damped. Just because new parts got bolted on, doesn't mean they're working. Either faulty valving or an improper spec would cause what you're seeing. From that photo, it looks like you changed springs too - what are the chances your shock valving doesn't match the springs? How can you be sure the shocks are working?

 

[Theshwed]

I wouldn't. Anything more than 1.5 strokes on the suspension from a single input (like braking) means the suspension is under-damped. Just because new parts got bolted on, doesn't mean they're working. Either faulty valving or an improper spec would cause what you're seeing. From that photo, it looks like you changed springs too - what are the chances your shock valving doesn't match the springs? How can you be sure the shocks are working?

Fair enough. That is the full Agile RIP kit; matched springs and shocks. The kit went on prior to tires, and i didnt notice the bobbing. But the van has had a lot of work lately in a short period of time. The suspension may still be or have been settling.

 

[brianjwilson]

Interesting. How many miles on the RIP kit? What psi in the tires?

 

[Theshwed]

Interesting. How many miles on the RIP kit? What psi in the tires?

Around 1k miles on the RIP kit. I am up to 65 psi front and 75 psi rear right now.

 

[Arctic Travelller]

I would give John at Agile a call.

 

[Buliwyf]

Text book shock problem. Time for real shocks if you ate Fox 2.0's that quick. It's possible they were valved soft for people that don't know what proper shocks should feel like. (Americans)

 

[s.e.charles]

"porpoising" - if the mechanicals are installed & working correctly, could weight distribution of payload be adjusted in fore-aft configurations?

 

[Raul]

At 65 psi your tires should be very hard and should not create any bouncing by themselves. My vote goes to the shock absorvers as well. When I did my MG conversion I got the Fox 2.0 from U-joint and one of the shocks blew up in less than 1000 miles. Chris got me a replacement very quickly and the handling improved significantly.

https://www.expeditionportal.com/fo...10-e350-5-4-diy-coil-conversion.167666/page-7