Agile RIP kit "gave" me death wobble??? - Page 2

nemesisnight · 04-30-2019, 04:55 PM

Quote:

Originally Posted by Pntyrmvr

Replace every single bushing on the vehicle.

Sounds drastic, but it worked for me.

I have, got new shackles and custom leafs in the rear.

front has new control arms (and bushings), new track bar bushings, new tie rod and ends, drag link isn't new but pretty tight, rotates but no play, new ball joints, not sure what else I can replace in the steering arena.

Only other thing that hasn't is the rubber mount that holds the sway bar to the frame (the axle bushings for the sway bar were replaced though) but I have yet to find out what the part number for that is, still need help there......

carringb · 04-30-2019, 07:28 PM

I agree with 5-6 degrees on caster.

Also going slight toe-in will make it a little more stable.

The sway-bar frame bushings are usually in stock at any Ford dealer. I have a couple sitting in my van now, but I'm not at home until this weekend, so I can't tell you the numbers. They were cheap. Not something I'd bother trying to match up aftermarket. Beware they come in 2 inner diameters, so it's really just easiest to come in with your VIN.

saline · 04-30-2019, 10:03 PM

Maybe I missed it but when you say death wobble are you speaking of a violent shaking of the steering wheel? Or is it a sway of the vehicle itself?

If it's a sway that requires white knuckle corrections it can be as simple as tire choice and pressure. Or a shot rear end..

So I had a very scary sway that would develop on my 04 EB SMB at highway speeds. A rut or a passing semi would send me all over and it was scary.
I noticed that my rear tires were wearing funny so I jacked the rear end up and I had a lot of play in my semi float axle when a jack handle was placed to lever the wheels.

I replaced it with a full float and the sway problem diminished substantially (no more play in the rear axle).

Additionally, I switched my tires to true E rated Toyo MT's. At 65 PSI they're rated for 3850lbs per tire. This strong sidewall and higher pressure reduced the amount of sidewall flex that more than likely contributed to the sway for me.

I know this may seem like a stretch but it's worth considering.

JWA · 05-01-2019, 05:09 AM

RE: Sway Bars & Bushings

It appears you're running the factory front sway bar and bushings in the I-Beams---I've replaced those with urethane parts from Energy Suspension to good effect. If replacing the I-Beam bushings that kit does come with new frame-mount bushings too---well worth the upgrade IMHO.

Not sure if a Hellwig front bar works with your 4x4 front axle but they do offer a choice of strengths based upon your chassis weight. FWIW I'm running an '05 E350EB former wheel chair lift equipped to which I've added Hellwig's short wheel base motor home (cutaway style). Those are significantly heavier and stiffer than anything stock or previously installed Hellwig bars.

Bilstein shocks for the same MH chassis give me on very firm ride but knowing my eventual built out weight will exceed what we'd use in a stock configuration. I don't mind if the ride seems too stiff because I know it'll "soften up" just a bit when I'm running at my normal daily driver loaded GVW.

Also if there are any factory "rubber" bushings still in the suspension attachment points consider urethane replacements there too. Keep in mind I'm NOT familiar with anything 4x4 so if what I offer is contrary to what's best in those systems feel free to ignore it.

Another aspect is caster---that does need to be pushed out a bit more than your current figures. Talking with a big truck shop specializing in frame/spring service might be better than chain store alignment shops. They're accustomed to going slightly outside factory spec's where the chain store shops cringe if you even suggest such a thing.

Best of luck with this---sounds dicey for sure.

nemesisnight · 05-01-2019, 09:18 AM

Quote:

Originally Posted by carringb

I agree with 5-6 degrees on caster.

Also going slight toe-in will make it a little more stable.

The sway-bar frame bushings are usually in stock at any Ford dealer. I have a couple sitting in my van now, but I'm not at home until this weekend, so I can't tell you the numbers. They were cheap. Not something I'd bother trying to match up aftermarket. Beware they come in 2 inner diameters, so it's really just easiest to come in with your VIN.

Is it a stock sway bar for a Van or a Truck? Since most of the front end is from a F250 with the Quigley conversion I assumed it was a sway bar from a truck as well, is this wrong. Does anyone know what energy polyurethane bushings I would need for my sway bar? Here are pics of my frame mounted one, it's pretty shot so it's worth a try before spending tons on a custom one with quick release although I would like to do that eventually too.

Oh and here is a new pic of the drag link and it seems to line up decent with the track bar

nemesisnight · 05-01-2019, 09:25 AM

Quote:

Originally Posted by saline

Maybe I missed it but when you say death wobble are you speaking of a violent shaking of the steering wheel? Or is it a sway of the vehicle itself?

If it's a sway that requires white knuckle corrections it can be as simple as tire choice and pressure. Or a shot rear end..

I do have a full float rear end that has had new seals in the last year and everything seems tight and this issue only happened after the RIP kit. But yes you nailed it, it's a vehicle sway and white knuckles are right on, it's terrifying thinking you will sway into another car.
My tires are rated about the same, maybe 3650 off the top of my head but I think that's at 80psi so that brings up a good point, I had them do 75 rear 70 front so I'll max that out to get all the help I can, the new suspension will help the ride. But again it wasn't an issue with my old shot suspension.

nemesisnight · 05-01-2019, 09:39 AM

So here is my solution and issue with my plan to get Caster...... So I plan on using these Jimmy joints to push my bottom control arms forward giving me more positive Caster

I will do this by cutting the end opposite the axle and welding in these threaded inserts (or rather a shop since I sadly don't have a welder and don't want to learn on this type of project)

Ideally I would like to do this top and bottom but unfortunately I have the fully boxed square upper arms so this method may not work for the top to give me the 1 1/2" push forward of the axle I ideally wanted for future bigger tires. If I do just the bottom arms I will still gain some positive Caster though, does anyone have any ideas on how to make the upper arms work with the square tubing and round threaded sleeve to still be strong. Without new upper arms and new shock mounts (since they are on the arms with my old style Quigley)

Here is what I have (sorry for all the mud, it was a wet weekend)

I am hoping this option will work and be fairly easy to get more Caster without new $1500 custom arms, and also changing my sway bar bushings to hopefully get rid of the death sway.

The only other option I can think of is a drop pitman arm to drop it back down 2" to where it was to reduce bump steer, but as I'm writing this I'm thinking it will make the angle of the track bar and drag link different so will that really help or cause more issues?

I really appreciate all the help, hope to get this fixed so I can go enjoy it.

velo47 · 05-01-2019, 10:08 AM

Quote:

Originally Posted by saline

If it's a sway that requires white knuckle corrections it can be as simple as tire choice and pressure...

...Additionally, I switched my tires to true E rated Toyo MT's. At 65 PSI they're rated for 3850lbs per tire. This strong sidewall and higher pressure reduced the amount of sidewall flex that more than likely contributed to the sway for me.

I had an old Suburban that was significantly under-tired for the weight we were carrying, and it had the same scary swing and sway. Higher load-rated tires eliminated the problem.

I know this still doesn't help explain why yours would start just after RIP install, but it's another data point.

carringb · 05-01-2019, 10:25 AM

Quote:

Originally Posted by nemesisnight

Is it a stock sway bar for a Van or a Truck?

That is a stock E-series sway bar. The in-axle bushings are the ones you want to switch to polyurethane. Moog sells them for about $15.

https://www.moog-suspension-parts.co...k80222#fitment

The frame bushing, I recommend keeping OEM. It has enough mass so it doesn't squish much until it ages, but they last a long time. Switching this one to poly can create some pretty good squeak as your suspension travels.

On edit: Moog has a delrin version now! This would address the squeaky mattress syndrome with the poly frame bushings. Beware this section of the sway bar came in 2 sizes. You probably have the smaller one linked below, but the wagons came with a bigger bar, so it's always possible yours was swapped.

https://www.moog-suspension-parts.co...uestionanswers

carringb · 05-01-2019, 10:28 AM

Quote:

Originally Posted by nemesisnight

The only other option I can think of is a drop pitman arm to drop it back down 2" to where it was to reduce bump steer, but as I'm writing this I'm thinking it will make the angle of the track bar and drag link different so will that really help or cause more issues?

Drag link and track bar angle need to match. Yes, reducing the drag link angle would help, but only you also drop the track bar angle by extending the frame bracket. Otherwise it makes it worse.