Steering issue

[Michael R]

I have MK 4 with Rack and pinion steering I didnt think I needed power stering but here in Michigan the roads can be sometines less than faverable.
Not many miles on the car yet but the other day it scared the sh_t out of me when I hit bump and the car over steared severly both directions.
The car has been aligned and has a sway bar, is there a way to tighten up the rack to slow this problem down or do I need power steering

[OVCobra]

Difficult to diagnose from a distance but it sure sounds like you have a very bad case of bumpsteer. If so, changes to rack or power steering will not change this, need to address the geometry issue.
JMO
Dave

[michael everson]

Need more info. Donor spindles or FFR? If FFR are the tie rod nuts on the top of the steering arm? Pretty sure Factory Five has solved most of the bumpsteer issues.
Mike

[Railroad]

What kind of front tire pressure are you running?

[Murd]

Do you mean true oversteer? The back end was sliding sideways one way then the other?
Front or rear sway bar?
What were you doing when you hit the bump? Straight, cornering, accelerating, braking?

[NAZ]

Like others have said, not enough info to determine what the likely cause. Think you should start with a grounding in terminology -- most will understand "oversteer" as the rear sliding (traction loss) or sometimes called "loose". I suspect you may have experienced bump steer but I have also experienced the wheel being forced to turn from a big impact (think pot hole) and this always comes with the steering wheel being jerked hard. Since you said it oversteered in both directions I'd think this is more likely what you experienced if you tell me that the steering wheel gave you a big jerk. If this is the case, the steering in both directions comes first from the initial impact and second from your reaction to the wheel being jerked hard.

Power steering won't help bump steer but may help reduce the uncommanded steering inputs from a wheel impacting a pot hole. Anything that reduces the steering effort will also help this as will adding a steering damper. If you have rather quick steering, rough roads in general will cause uncommanded steering inputs. One driver trick to mitigate this is to drive with your elbows tucked in close to your sides. It will lessen your unintentional steering inputs from your body being tossed around during a rough ride.

[CraigS]

Power steering can help in one way. W/ PS you can run more caster. This raises the height of the steering arm end where the tierod attaches. This usually helps w/ bumpsteer. The two MkIVs I have checked, both w/ FFR spindles, the bump steer was almost perfect w/ +6.5 deg. caster.

[RBachman]

Not sure about the FFR roadsters, but typically if you have bad bump steer or "death wobble" something is not aligned properly.

[NAZ]

Death wobble is not the same as bump steer and death wobble is not caused by alignment unless you want to include modified suspension, and incorrectly installed or worn components under alignment. It is mostly found in solid front axle vehicles like 4X4s that have been altered such as lifting or the components are seriously worn. This condition can be very annoying to downright dangerous but is not what the OP described. In a death wobble the front tires will rapidly oscillate and the steering wheel will shake hard. This may last until you lightly apply the brakes or slow your speed. Anyone that has experienced this will never associate it with bump steer.

Bump steer is a suspension geometry issue that causes uncommanded steering input of one or both tires when the suspension travels through compression and rebound. The steering wheel typically does not move from bump steer, however, it may seem to move as you unconsciously react to correct the uncommanded turn.

[RBachman]

Death wobble is not the same as bump steer and death wobble is not caused by alignment unless you want to include modified suspension, and incorrectly installed or worn components under alignment. It is mostly found in solid front axle vehicles like 4X4s that have been altered such as lifting or the components are seriously worn. This condition can be very annoying to downright dangerous but is not what the OP described. In a death wobble the front tires will rapidly oscillate and the steering wheel will shake hard. This may last until you lightly apply the brakes or slow your speed. Anyone that has experienced this will never associate it with bump steer.

Bump steer is a suspension geometry issue that causes uncommanded steering input of one or both tires when the suspension travels through compression and rebound. The steering wheel typically does not move from bump steer, however, it may seem to move as you unconsciously react to correct the uncommanded turn.

My experiences are different. I had a new IFS 2015 Toyota with less than 1500 miles pull a death wobble when hitting a bump just right. It was due to an alignment issue along with a bump steer issue. An alignment fixed both. I know that Ford had some issues with their SUVs and trucks. The fix was to increase the caster, replace/adjust the track bar and replace the steering dampener. But I do agree on it being more prevalent with 4x4's and solid axles, especially with cheap/extreme and poorly installed lift kits.

[Michael R]

32-33

[Michael R]

I'm going to address my terminology and try to explain it better I need to go home and look for additional information Thanks

[Michael R]

Front sway bar and I was going straight 4th gear just normal acceleration speed about 40

[Michael R]

FFR and the nuts are on the bottom I think, I'll get back to you

[Michael R]

going straight not accelerating just a lot of input to keep it going straight

[Michael R]

I'll check my alignment spec sheet to see the setting

[Michael R]

It tracks straight on a smooth level surface and was aligned on a Hunter

[Michael R]

yes on the terminology I might not have explained correctly. It wasn't a pot hole more like 5 ft of rough and uneven black top. The problem was I was able over correct very easily not as common in automobiles made to todays standards. I just wish there was a way to tighten up that feel, it was to say at least surprising.

[Big Blocker]

1st - If you answer in post #11 (32-33) is tire pressure, you are running WAY TOO MUCH!! Normal for our cars is 22-23 with the rears having a pound or two higher than the fronts. Your tires are pumped up so high that they don't have any chance for the sidewalls to work.

2nd - What alignment specs are you running with your manual steering, mostly toe-in / toe-out spec?

3rd - How many turn, lock-to-lock in your steering? quick ratios will compound a bump steer issue. That being said, F5 has almost completely eliminated bump steer issues with the MK-IV and their newest spindles.

We all need more information to help you with your issue . . .

Doc

[Jeff Kleiner]

32-33

If this is your tire pressure then as Big Blocker said it is WAAAAY too high. 22-23 would be appropriate


FFR and the nuts are on the bottom I think, I'll get back to you

If this is in answer to to the type of spindles and whether the tie rod nuts are top or bottom the steering arms and tie rods are assembled incorrectly. The steering arms should angle outward from the spindle, the tapered hole should be wide at the bottom and tie rods installed so that the tapered stud goes in from below with the nut on top. If they truly were installed opposite with the rods above the steering arm it would induce a great deal of bump steer.

Jeff

[davekp]

Pictures would really help.