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Rear end wander on icy roads

25K views 43 replies 17 participants last post by  elsolo 
#1 ·
Had a bit of a little snow storm blow through the other evening, and I had to make a 40 mile trip on the highway.

On the icy patches, where the road was ice rink slick, the back end of the car kept wandering around, like someone was shoving it from side to side, or fishtailing badly. Very disconcerting above 25 or mph.

I bought the car used in August. The tires are all the same brand and model, but the front pair were in better shape. The back were worn down pretty good, but I didn't think they were completely shot. Goodyear GS-A's, I think they were.

Its been absolutely fine otherwise, rain, and dry.

I ended up putting a new set of tires on the next day, but the ice had cleared up so I couldn't confirm, was this just a bad tire problem? Or something else?

I mention it, because a co-worker says he's had the same problem in his 2003 ZTW. And he's been back and forth with the dealer, and tire shop i think.

2002 Focus SE sedan
 
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#37 ·
thenorm - honestly, the "wiggle" in my experience came from toe-in - so minimizing that should help. (Winter driving specific info., summer or performance driving preferences could vary)
 
#39 ·
Hmmm...

I'm seeing a MAJOR adjustment (needed) to front toe, as well as a change in L.R. camber.

The ODD thing, is that there isn't a "shim" to adjust camber on the Focus (it COULD be done, but it would be quite difficult) The normal way to make such an adjustment would be with a "camber bolt", which replaces an upper control arm bolt and can be twisted for some adjustment, then tightened in place.
 
#40 ·
He called it a shim. I suppose I could look and see what that part looks 'new'. He charged me, like $70 for the part. Sound about right for a shop cost + markup? I plan on keeping that sheet he gave me, and going back in a few months, maybe when winter is over, and getting it checked again, and make sure its not going out of spec over time...
 
#41 ·
Sounds about right for the camber bolt (would be silly expensive for a "shim").

When people use generic descriptions that don't really apply, you begin to wonder what they actually are doing - or what kind of wool they're trying to pull over someones eyes....

I've heard it explained that "people won't understand the real description anyways" as a reason for such verbiage - seems like a poor excuse for not attempting a proper explanation...

Looks like you got fixed up in any case!
 
#44 ·

There are rear camber shims available for the focus, they are tapered and the kit retails at $70
Customer probably only got part of the box of shims, but there is the install too. Half box of shims plus an extra half hour labor. $70 is not too bad.
 
#42 ·
the camber bolts cost about $30. 70 installed would be reasonable.

front alignment looks good.
keep and eye on rear tire wear still. the rear toe could be reduced further to 0.1°.
 
#43 ·
thenorm, you stated

'i dont believe that a very slight toe out will cause the wobble.'

You should drive a double positrac four wheel drive with toe out and see just how creepy toe out under power is on front end, the vehicle constantly darts one way and then the other with no warning. One of the most unstable setups there is, terrifying to drive. The tires try to pull car in two different directions.

With toe out the tires will constantly be fighting each other to go opposite ways, you may not see it on dry pavement but that's exactly the type of scrub and slip that could easily untrack car on very substandard conditions like ice. Both toe in and toe out scrub tires but toe in scrubs and both sides pretty much slip evenly as they are scrubbing. Reason why is that both tires are trying to come together, if suspension tight the slip is gradual and evened out, the tires can only drive against each other so far before they HAVE to slip and keep on doing it. Toe out more like one tire scrubs a bit then slips when other tire yanks it back. An alternating slip-slip-slip as the two tires fight with each other. May not be dead even one for one trade either. They trade slip because tires are moving away from each other and at some arbitrary point one gives in to the other. The car weight trying to yank tire back straight in line (think of a trailer) adds to it too. The scrub/slip at same time does much less to untrack car in ice than the alternate scrub and slip. Slip in second case is worse because it accumulates before relief rather than being dissipated gradually.

Basic difference..........toe in, tires can both be out of dead straight but their combined motion can still result in dead straight tracking, toe out cannot do that, one tire goes one way and the other one goes its separate way, no way to make them work together. The skittishness from that makes hell on ice, or rain for that matter. You won't see slight amount affects unless you lose control of car too easily, that's it showing up.

Ford's reason for more weight increasing toe..................designed in for safety.

By 'scrub' I mean rubber rolling not dead straight, the friction is at an angle and not in line with tire sides. It produces the feathering on tread blocks.

By 'slip' I mean any giving of tread to neutralize distorting forces, the tire could actually slip on road surface (in water or on ice) or tread blocks can squirm to relieve that scrub force. Yes, a very small amount occurs on dead straight normal tires. A small amount allows tread to fit into road irregularities for better traction but more can be bad. It kills tire life past a certain point.
 
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