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Old 04-03-2006, 03:06 PM   #1
Cheffy
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Rear bump steer - normal?

Hey everyone, I just got a 2001 focus wagon with the Zetec engine and a 5 spd trans, and I and learning to love the car. My previous ride was a 92 legacy wagon - versatile, but not exactly too sexy.

Now I love the shift, the acceleration, the look, and most everything about this car - except the handling! Don't get me wrong - it corners amazingly well, makes my old sube seem like a tank in comparison. But... it seems to have problems with rear bump steer. The dampening seems fine, hitting the bump itself isn't too harsh and doesn't bounce excessively. But the rear tires seem to want to "kick out" after hitting some bumps. PLus sometimes it seems to follow ridges on the road, and wander. And, when there is a somewhat rippled effect on the road, it seems to "waddle" side to side a bit. Strong cross winds exagerate this effect, making highway driving very tedious and sometimes aggravating. I keep thinking people must think I am drunk or something the way I must be swaying.


I know the rear suspension has some mild passive steering, which may alter toe on bumps. But this seems excessive. I'd really like to know how normal this is, and what I can do to minimise it. I do a lot of highway driving, so it's important to me. This car has been dealer serviced, and I intend to get all the records for it (I bought it at an independant place). MAybe somethign there will help me.

I respect and appreciate all those who change their suspensions for performance, but me I'm happy with a stock suspension, provided it works well. So I'd prefer to avoid solutions that are geared to performance rather than comfort. A quick look in the rear doesn't reveal any worn or damaged components, but I'm not very familiar with the set-up on the focus compared to most other compact cars.

Thanks all for any and all input - I've been reading these forums for a week now, and am quite impressed with the knowledge and willingness of everyone to help out.


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Old 04-03-2006, 04:55 PM   #2
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The rear tires do the same thing in my SVTF and I hate it. I think it is alignment related myself. Mine isn't real bad and I don't have the "wandering" affect but I would have the alignment and tires checked out. Granted my car is an SVTF and has stiffer springs and dampers but all-in-all, the suspension set-up is basically the same. Hope you get it firgured out and I will be having my alignment checked soon.
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Old 04-03-2006, 05:21 PM   #3
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Yup my car has the same thing.. Everything that Cheffy described. I've had 3 suspension setups (stock, lowing springs, full coilover) and in all three setups I've had that same problem. I'd go over a man hole cover with the right 2 tires and once my back tire drops into the manhole the rear of the car will kick out.
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Old 04-03-2006, 06:13 PM   #4
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Well I suppose it makes me slightly relieved to hear that it's "normal". I guessed that the naturally tight suspension combined with the rear passive steer toe out might make this a normal effect, but I must admit it's a bit irritating on a relatively new car. One of the reasons I got rid of my old sube is that it was suffering from a similar effect, but on the front wheels. Worn rack/inner tie rods in that case though.

I have brand new tires that came with the car, mirada sport gtx, inflated to 35 PSI all around - seem to grip well, but maybe these cheapie tires don't exactly help matters. Or maybe a better gripping tire only exagerates the problem too?

I'm all for ideas on trying to fix this problem, and might try to find a place that checks alignments for free. I've read that several people here feel the car is very sensitive to slight mis-alignment. Perhaps there is a little too much toe-out on the rear.

Thanks for the fast replies!
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Old 04-04-2006, 09:35 AM   #5
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I've been searching here for alignment info, but can't seem to find much. What are the stock alignment specs for the focus? I assume there may be some differences bewteen the hatch, sedan, and wagon. I'm thinking perhaps either stock rear toe out settings for the focus may be excessive considering the tendency to increase during turns, or that maybe that the vehicles we drive have been set for the incorrect type. It would be good to hear some input from more focus owners.

I'm assuming there should probably be 0 toe at the rear stock, likely the same for all models (except the SVT). Perhaps dialling a wee bit of negative toe on the rear may help (suggestions for amount?). Any thoughts? I really like this car so far and don't want this to ruin the experience.
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Old 04-04-2006, 09:48 AM   #6
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There isnt much REAL talk about suspension around here. People just want to see the Lowered effect. I lowered my car. And I cant find a garage around here to do an alignment for me because they say my car is to low to get up the ramps. So I feel stuck.
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Old 04-04-2006, 10:03 AM   #7
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Hmm, I can only spit back what I've learned pouring over posts here and elsewhere, but here's what I have to say.

I havent in particular noticed this effect in my SVT, its an 04 with stock suspension. Extreme bump oversteer, my first guess is the rear dampers. You've already said the damping feels fine, but if you havent already done so do a quick bounce check. Obviously, if the action feels too light and the rear bounces instead of coming right back up to rest, your dampers arent dissapating the energy quickly enough, and the spring gets to cycle more than once, unloading the rear contact patch and exaggerating oversteer.

Tendancy to follow grooved in the road I've always seen described as a sideaffect of strong negative camber. This causes the inside edge of the tire to load up more than the rest of the contact patch in steady cruising, so a small change where the load is concentrated can have a larger affect. As I recall, factory specs on the front camber arent anything crazy, but in the rear up to -2.3* is concidered inside spec. Later in the run there was a new control arm released to bring this up by 1*, to -1.3*, which is pretty nominal, -2.3* is pretty extreme. Its the cause of the unever tire wear focii are well known for. Given you have a 2001, I imagine your rear tires are cambered out pretty far. However, thinking about that, rear squirm wouldnt be as noticable as if your front were out of spec, and technically strong rear camber should resist oversteer.

Toe, like you mentioned, would also play into it. If your tires were toed out somehow, I'm not sure what the factory spec is, it'd encourage oversteer. Maybe if you toed it in an 1/8" you'd gain some stability without doing much damage to your rear tires, toe either way causes scrub on the edge of the tire.

You sound like you know what you're talking about, you'd probably be able to tell if you had a set of failing rear dampers, so if its not that I'd spring the $50 to get an alignment, then maybe tweak the toe a little to get your desired results. I BELIEVE rear toe is adjustable in the focus, there's an oblong bolt or something you can use, a search should be able to bring this info up.

Good luck!
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Old 04-04-2006, 11:01 AM   #8
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Yeah, the rear toe is adjustable. I didnt have that problem a few weeks ago, but the inside of my tires were worn down badly while the outside were ok. I took it to the shop, but they couldnt get my car over the alignment machine. I got new tires, took it home and put the toe out just a little to see if it would help with the wear. The next day i had to drive 3 hours down the interstate to come back to school. I noticed when hitting bumps or changing lanes where the road was rough, i got a little oversteer. I dont know much about the effects of suspension tweaking, but it seems that putting the toe out will give to the oversteer. I dont have a stock suspension, and i know that my rear camber is around -1.5 deg.
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Old 04-05-2006, 08:03 PM   #9
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Well, thanks for all the great info folks. I'd have to say in general the car definitely tends towards understeer, but really pushed or hitting bump the rear seems to toe-out and then quickly back in. It's tendency to wander is mostly due to a high crosswind sensitivity, being a wagon and all. Overall the problem seems more annoying then dangerous, but something I'd REALLY like to be rid off.

Been doing some more research on this and a walk through google forums seems to reveal a LOT of people with the same problem as myself, while severla others with no problem at all. Here are some relevant threads:

http://groups.google.ca/group/alt.au...865a721fa30ed1

http://groups.google.ca/group/alt.au...us+unstable&rn

um=2#b4aae30a84148810

http://groups.google.ca/group/alt.au...us+unstable&rn

um=9#46edb27a9017d002


Anyways, there seems to be little discussed regarding solving the problem, but at least one person suggested that a good alignment shop that changed the specs from Ford factory standard managed to cure it.

"I just solved my rear jumping around problem that has been with me
since new. The car had been aligned by Ford, shims installed, other
shops aligned it and still it would jump around. Also the left rear
tire wore real bad and was making lots of noise. Car was not quiet,
not fun to drive any more and only had 34k on it. I was running the
original tires at 40lbs pressure and not rotating them.

I went to a local tire shop and talked to them twice and even went out
and talked at length to the alignment guy. He told me, don't worry, I
CAN align that car and you will be rid of the handling issue, trust
me.


Well - to make a long story short I purchased 4 new tires and the
alignment and he was true to his word, my problem is gone, I look
forward to driving the car again, it's quiet, does not jump around and
I am VERY happy with it now. It's a 2001 SE wagon, I would buy
another for sure. I just love the car and I get 35 to 37 on the
highway with it even going 70 mph. "

I will call a ford dealer and ask if they'll check my alignment to see if it qualifies for the TSB regarding rear negative camber. If they fix this and the problem persists, I will seek out a good shop for an alignment.
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Old 04-05-2006, 08:05 PM   #10
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BTW, some musings about the Focus suspension by a guy of the google forums I found interesting:

"The focus suspension has

2 lower lateral links
1 upper lateral link
1 1 stamped trailing link with a voided rubber bushing connecting it to
the body, and an integral hub carrier.


all lateral links are bolted to the trailing link's hub carrier. the
voided bushing allows fore aft compliance for ride comfort. The passive
rear wheel steering works by having a softer bushing in one of the lower
lateral links, allowing the wheel to toe out / / minimizing unexpected
oversteer. In braking (my theory) this also allows the wheel to do this
\ / for stable stops. In bumps this may lead to a toeing out slightly \
(my theory) the anti roll bars may be different/or not strong enough for
the wagon allowing one wheel to do this \ while the other |.


in conclusion Ford sacrificed low speed ride for high speed stability. "

Here he mentions a softer bushing at work - I wonder if this may compromise ride over bumps.

Also:

"the focus suspension is just a standard unequal length
control arm suspension.

the difference is in the extensive use of stampings in place of parts
that would normally be cast or forged. This lowers unsprung weight and
cost.
ford uses a stamped trailing link. the link where the tire is attached,
the stamping replaces an almost universal cast iron part, forms the rear
hub and is where the lateral inks are connected. at the front where the
the link connects to the car, the the link is about 2" tall and there
is a rubber disk about 1.2" in diameter, with rubber cut out for
fore/aft movement.


the lateral links control the lateral movement and to control the angle
the wheel touches the ground.
]
The combined arc of the lower link ")" and the upper link ")" creates a
an arc that keeps the tire in level contact with the road. "|" . the
Aft lower lateral link is a stamping that the spring rests on and shock
Absorber connects to it too. the anti roll bar is bolted to the rear
link also. The front lower link is, far less robust than the rear, is
there to locate the wheel / vs \ is probably where the passive rear
steering geometry is located. the upper lateral link is shorter than
the lower links to tuck the wheel in to the wheel well and to aid
handling. like the SLA on the front of of some cars.


the Focus's rear suspension has very good wheel control but is very
compliant. ford likes it because it is cheaper to make and assemble
because the rear axle is a rebuilt module that just bolts to the bottom
of the car at the factory. quick and easy. "
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