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Discussion Starter #1
I figured you guys might know: After new springs and wider wheels/tires, I now notice my steering pulls around a lot when driving on the freeway where there are ruts or groves worn in the road way. I used to notice this a bit with stock setup, but not to this degree. Anybody experince this before? Is there a fix for this. Is this similar to bump steering?

THanks.
 

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My car used to do that with the stock springs. After installing c springs, x2 ball joints, and upr bumpsteer kit it tracked better than it ever had. Edit: After 20,000 miles it is just starting to follow the ruts a little now but nothing like it used to. I have a little wear in the heim joints of my bumpsteer kit and new ones should arrive today so that may cure it. I also need to check the alignment again since I've been moving it to max negative camber for auto-x then just pulling it back to the lines I scribed when I first set it up.
 

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It's not bumpsteer, it's called "tramlining". We're stuck with it to some extent thanks to the scrub radius built into the suspension, which makes for the tire having quite a bit of leverage over the steering.

Some of the biggest variables that contribute to it and therefore can mitigate it are:

TIRES: The wider the tire and the stiffer the sidewall, the more it'll happen. Also any "conicity" or uneven treadwear as they wear will make it way worse.

STRUT BUSHINGS: The slop in the stock strut bushing allows a lot of movement, and installing good caster/camber plates makes a big difference

A-ARM BUSHINGS: The more compliant they are, the worse the tramlining will be

RACK BUSHINGS: See above

ALIGNMENT: The more negative camber you have, the more it'll tend to tramline

TIE ROD ENDS: Worn inner or outer tie rod ends contribute to this as well as other problems

BALL JOINTS: See Tie Rod Ends

Bottom line is, the fresher your suspension is, the less you'll notice tramlining. The fresher your tires are, the less you'll notice tramlining. The narrower your tires are, the less you'll notice tramlining. Above all, the less slop you have in the front bushings, the less you'll notice tramlining, and until you eliminate that slop, you're pretty much chasing your tail. Even then, you'll still experience it to some extent, again because of the scrub radius built into the front end.
 

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I noticed it after adding 18" wheels with 245/35 series tires. Sometimes it bounces me around in my lane and can get scarry going fast on bumpy roads with little space around me.
 

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Discussion Starter #5
Jgorm, what are you going to do about it?

I will look into the items that MFE has suggested. I can live with a little "tramlining" I guess, but will have to test my car out some more to determine how bad it really is. I know a lot of people are running 9" wheels and 255+ tires up front so I am curious what they have done to reduce the issue.

Thanks.
 

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For now just keep my eyes open and hands on the wheel. Usually the car only moves up to about 8". I have 9" wheels with 245/35/18. It only happens if the bump/ groove is over about 1" high, so only on the rough sections of the roads.
 

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krtw,
The first thing you should do is check the camber and toe in. 1/2 to 1 degree negative camber and 1/16" toe IN should work fine on the street. I use 1/2 degree on mine and it works good for me. Make sure you have good shocks. If you have caster camber plates don't run to much caster for street driving. It tends to try to pull the car straight but can wear the inside and outside edges of the tires and makes tramlining seem worse. (just my personal experience)

If you have tires that are not worn unevenly and follow the setup I gave you in my previous post you should have a good driving car.

To recap for a good handling quiet riding car I suggest:
extended ball joints with thicker upper isolators rather than the aluminum spacers. The spacers made a popping noise in my car so I went to thicker isolators to cure that.

offset lower control arm bushings to gain a little extra positive caster

bumpsteer kit (set tie rods at the same angle as the pivot angle drawn from the center of the a frame bushing to the center of the ball joint pivot point)

stock camber plates in good condition (this is because caster camber plates usually get noisey if you don't constantly change the top bearing)

These are components and settings I have personally had good results with. Others will disagree on some point or the other, most likely on the stock camber plates.
 

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Han Solo said:
stock camber plates in good condition (this is because caster camber plates usually get noisey if you don't constantly change the top bearing)
Sorry, but I can't possibly disagree with this more. For one thing, even the stock mounts "in good condition" allow an amount of slop that will make your jaw drop, and that's exactly the opposite of what you want for reducing tramlining. For another thing, while the spherical bearings in better c/c plates do occasionally loosen up to the point of making noise, it certainly isn't endemic to the whole category. I had one loosen up on me and MM replaced it for free. That was years ago, and I now have at least 50,000 miles on mine including at least 1000 track miles and too many autocross runs to count...and they're silent. I wouldn't trade them for the slop in a stock mount if you paid me.
 

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Discussion Starter #9
What about the fact that with the new 9" wheels up front with 255s do appear to stick out a bit more as compaired to the rears. I am wondering if this contributes to the issue as well.
 

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Yes, the tire width is definitely an issue. Remember, a lot of this is due to leverage of the contact patch (wherever it may be at the moment, and ruts cause it to shift) on the steering linkage about the steering axis. The wider the tire, the more leverage ie exerted when the outer edge tries to climb the rut.
 

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MFE said:
Sorry, but I can't possibly disagree with this more. For one thing, even the stock mounts "in good condition" allow an amount of slop that will make your jaw drop, and that's exactly the opposite of what you want for reducing tramlining. For another thing, while the spherical bearings in better c/c plates do occasionally loosen up to the point of making noise, it certainly isn't endemic to the whole category. I had one loosen up on me and MM replaced it for free. That was years ago, and I now have at least 50,000 miles on mine including at least 1000 track miles and too many autocross runs to count...and they're silent. I wouldn't trade them for the slop in a stock mount if you paid me.
That is exactly why I made the closing statement and note I said these are components and settings I have personally had good results with. I invite anyone on the board to come take a test drive in my car.I have had it transend through most situations I've read about and I believe it handles and drives as good as any you have ever seen for a combined street/auto-x car.

BTW, I am running 275/40/17's on 9" rims on front and 315/35/17's on 10 1/2" rims in the rear.
 

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You may very well have had good luck with the stock mounts but that doesn't by extension mean you need to "constantly change the top bearing" in aftermarket c/c plates to keep them quiet (sorry, that's utter hogwash), or that it wouldn't actually be better to use something with more positive location, not to mention adjustability, than the stock type mount.
 

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Its basically a change in contact patch (not alignment) that causes the car to follow ruts in the road.
My 275's on 17x9-1/2" rims wanders more than a flock of sheep... I just live with it on the street that way.
 

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MFE said:
You may very well have had good luck with the stock mounts but that doesn't by extension mean you need to "constantly change the top bearing" in aftermarket c/c plates to keep them quiet (sorry, that's utter hogwash), or that it wouldn't actually be better to use something with more positive location, not to mention adjustability, than the stock type mount.
You are correct. There are performance gains to be had with quality CC plates and there may be some that don't need constant maintenance on the upper bearings. I only have my own personal experience to draw from and admittedly the only CC plates I have tried were a set I made myself and chose a bearing that wasn't up to the task for long. I have also read other posts of people having the same bearing wear problem I had with store bought plates. The plates I made also had the capacity to gain enough positive caster that while running them at full caster I wore out a set of front tires in about 7,000 miles which was about how long my bearings lasted before starting to make noise.

As satisfied as I am with my current handling and ride I will probably experiment with other options in the future. I like to make my own stuff whenever possible and I made a set of drawings for a set of 4 bolt plates with precision bearings. I made the last ones from 1/2" aluminum with 3 bolts but the next version would most likely be 1/4" steel with 4 bolts. I also have plans to make some rear upper and lower control arms with spherical bearings on the rear connections of both instead of the front location chosen by most manufacturers of those. No guaranty I won't return it to the present state after trying all of this though. LOL

The stock plates are a usable component that will achieve a comfortable ride along with adequate handling when using offset LAF bushings for a little caster gain.

I guess the main thing I should warn people about is not to run to much caster on street tires. It makes it handle better by feel but can eat away at the edges of the tires.

I did have an instructor who drove a 911 Carrera tell me my car handled the transitions at Road Atlanta better than a M3 BMW he instructed in a week earlier. That was with the car set up in it's present state, stock camber plates and all. Of course you never know what state of disrepair the M3 was in.
 

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huesmann said:
How does caster eat away at the edges?
Positive caster leans the tires into the turns effectively creating positive camber on one side while creating negative camber on the other. To much of it wears the inner and outer edges.

Examples:
In a right turn the wheels will look like this / /
In a left turn the wheels will look like this \ \
 

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It creates negative camber on the outside wheel though, where you want it.
 

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Can someone describe to me how excessive caster can wear tires on a Mustang?

On a car that takes up to 2 degrees negative camber to NOT wear outside edges, how would the addition of caster cause outside edge wear in any measurable amount?

DaveW
 

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Most of the time you are driving straight on the street so how does postive caster cause drastic wear? I can see negative camber doing that but not postive caster???
 

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silentst2000 said:
Most of the time you are driving straight on the street so how does postive caster cause drastic wear? I can see negative camber doing that but not postive caster???
My last reply on this one! :curses:

Aparently you can get away with 5 to 6 degrees positive caster as many have said they are doing and this is about all you could expect from just haveing CC plates. On SN95 cars you got a little more caster from the factory than fox cars did. Add to that some offset aframe bushings and you are up to 4+ degrees of positive caster. Then you put on CC plates and shove them to max caster and who knows what it comes out to be.

All I know is when I had CC plates and ran max caster on them with my offset aframe bushings on my 99 GT it ate the inner and outter edges of the tires up. :curses:
 
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