Newbie w/ 1994 F-SUPERDUTY (450) Violent/Deadly shake! Help!

[krawlr]

BTW, I own a lightly modded 96 Grand Marquis as well. What swaybars you running?
You can read all about my mods here http://www.crownvic.net/drock96marquis/MERCmods.htm

They're just Addco's from Summit. 1 1/4 front and 7/8 rear. Yours looks very clean compared to mine.

http://www.krawlr.com/panther/panther.htm

 

[82fordtruck]

would a shackle reversal help here?

 

[RedTruck]

dRock96f450,

I have experienced exactly what you speek of with my rig. I called it violent wheel hop whenever I talked with someone.

Details of my situation:

Background:
My rig is an '84 F250. I replaced the independent front with a solid
D60 from a '94. In the midst of upgrading I did some research on
the leaf springs. It turns out that because of the physics involved
with the independent front suspension the springs are a heavier
weight spring. I decided to keep with the original independent
springs with my d60 upgrade.

Problem:
When I took my rig for a drive after the upgrade, everything was
going along nicely. It ran out just fine. Then I hit a few small
bumps in the road and I literally almost got thrown from the cab.
Uncontrollable wheel hop. I gently hit the brakes as everything
continued to shake till I stopped. After that I could feel it in the
steering wheel before it would happen, so I'd back off or stop so it
would quit

Research:
As near as I can figure, the caster was really off. I believe the
bumps in the road would initialize the bounceing and the vehicle
would force the front end into the road causing the bouncing to
get worse. Kind of like dribbling a basketball.

Fix:
I checked with a few places on replacement springs. There were
several spring packs available for my application, but every one of
them created different caster for different applications. I found
a set of 1 ton springs at a bone yard from a '94 one ton and replaced
my old springs with those. If they didn't work I could bring them back
to the bone yard for replacement...I had this worked out ahead of time.

Currently:
After upgrading the springs it works great. I've pulled 25,000 lbs 600
miles with not so much as a shimmer in the steering wheel.

You mentioned you had the front springs replaced. When you replaced them, did they use springs matched to the VIN number on your rig or did they match the new springs to the old ones? Is the frame bent at some point that would throw off your front suspension angle? Are you're shackles bent or broken?

I agree with some of the other folks that a good alignment would help. I'd mention that you think you have caster problems and that you may need a shim, so they can pay attention to that during the alignment. It's hard to find a good alignment shop.

Also, if you need another point of few on your situation, the people at Husky Spring may be able to give you some ideas.

Good luck,

Paul

 

[f-two-fiddy]

You might want to inspect all the linkage mounting points. I've heard of the 'Death Wobble' actually breaking rivets on some frame mounting points.

 

[dRock96f450]

You mentioned you had the front springs replaced. When you replaced them, did they use springs matched to the VIN number on your rig or did they match the new springs to the old ones? Is the frame bent at some point that would throw off your front suspension angle? Are you're shackles bent or broken?

RedTruck (and everyone else for that matter) thank you very much for your reply.

To be honest, I could not tell you if they did it by vin or by part match. The spring change was done a few years ago now, about ~40k miles ago. Maybe we should look into some custom stiffer springs? The springs on it now look the same as the factory springs on my 96 f-450, both use the same spring code as well, so I assume they did it via spring code. The shackles appear to be in tip-top shape, is there anyway to visually identify worn inner bishings easily without removal?

The frame is straight and true. I have noticed it does flex some in rare occurances (ie traveling over traverse terrain), and it was accounted that it was only more so noticable as he has a long wheel base. The steel landscape body, mounted on the rear most part of frame, indicates when this is occuring as the body moves but the cab will not as much. Mine seems to do the same thing, but with the much shorter wheelbase it is not as noticable, so I take it this is normal

Another thing i have noticed, his springs have always seemed much softer in comarison to our other trucks. For instance, my truck feels like the axles are welded directly to the frame without the use of a spring when there is no extra load in the truck ;p Where as his rides closer to a passenger car.

Mine: Can take corners as fast as the tall and squishy tires can allow, with zero body roll.

His: Feels like a beached whale ;p

I agree with some of the other folks that a good alignment would help. I'd mention that you think you have caster problems and that you may need a shim, so they can pay attention to that during the alignment. It's hard to find a good alignment shop.

We are going to ask some of the local tow-truck operators where they get their alignment work done in hopes of better results. I looked into the road force balancing some, I found a place that can do it but they won't take in large dualies So I am still thumbing through the phonebook ;p

THanks again for the help guys, I really appreciate your input. I wish he would have gotten rid of this truck when he first contemplated it, but he has always liked it. It came with a nice sounding radio, A/C, nice paint job, and is very quiet inside. Makes me think Ford decontented the sound insulation in my 96 lol. The truck may just be cursed though

 

[supercab79]

DROCK I work for VERIZON formerly Bell Atlantic and we have about 200 F450's from 91 to 97 in my garage alone and our Motor vehicle depot works on trucks from 8 different garages. I drive a 97 F450 with a Telsta 35' bucket and all of them do this at one time or another. I like to hang around our Motor vehicle depot to see whats up for grabs as far as stuff and info and a while ago about 4 years ago the one and most common fix that our motor vehicle department has found that works is to simply replace the trac bar or if you would like to save a alittle $ you can just replace the track bar bushings. Now alot of money, time, theories and parts have been tried and it has now been accepted that all the mechanics start there and no kiding around 95% of the time it's the colprit.


Good luck this is a good fix for 4x4 F350's that do this also.
Marc

 

[94f450sd]

ok first off the F450 is a completely different animal from the F250-350.

second check the front end REAL good!king pins,tierods,drag link,wheel bearings,steering box,steering shaft from box to column,trac bar,U bolts,tires,spring bushings,stabilizer.

i had this death wobble in my 450.i needed king pins bad!i replaced the front axle and the wobble went away.

 

[bikepilot]

When I was working at an auto shop, the construction guys next door asked us to look at their truck (was an F-450 IIRC) saying it had a terrible shake that nearly caused an accident. IIRC we found the track bar (the bar that's nearly horizontal across the front to keep the solid front axle from moving side-to-side bushings to be totally shot. Replaced them and all was well.

I'm sure there are other things that could cause the same symptom, but its something to check.

good luck

 

[Agnem]

Welcome to the forum. Your getting plenty of good advice now.

 

[adrianspeeder]

Welcome, hope you get it fixed!

Adrianspeeder

 

[offroadohio]

Glad I found this post, I'm having this issue aswell. Found a loose steering box on mine, and havent gotten to test it yet, prefer not to exsperiance death wobble again, not so bad in a little lifted 4x4, but an f450 is totaly differant. Alot more lvies at stake than you own when ya hit that little geometro in the other lane.

Trackbar bushings is something i didnt think to check, gonan check those out now aswell

 

[93turbo_animal]

welcome offroad wheres roseville at?

 

[offroadohio]

Few miles south of Zanesville ( 45m west of columbus) Ive been to Marengo but forget where it is. I travel alot.

 

[93turbo_animal]

Oh Ok I get to zanesville for tractor pulls and was just down to the freeland valley tractor show

 

[offroadohio]

The pulls at the county fair?

We've got a monthly pull in Glenford thats a pretty good show. Also one at the hunting club up the road.