Tie Rod Extenders?

[tikibeast]

I'll skip the long drawn out story but while leaving the beach the other day I committed one of the cardinal sins of driving. Driving aggressively while tired fortunately nobody was hurt and no property was damaged aside from my own, I nodded off in a curve and woke up just in time to watch my driver's side front wheel smash into the curb. Fortunately I can only assume my foot had come off the gas because I wasn't going fast enough to do much more than road rash the hell out of the lip on my rim. On the down side it knocked my alignment out and when I took it in to get aligned my shop told me A my car is too low to guarantee any work they do on it and B as low as my car is they feel I need a set of tie rod extenders to straighten out my tie rods. I've heard of using these on Miatas and Rhinos but this seems a little odd considering when I got the tires rotated and got everything aligned a month or so ago there was no mention of this.

 

[N8Dogg98]

I'll skip the long drawn out story but while leaving the beach the other day I committed one of the cardinal sins of driving. Driving aggressively while tired fortunately nobody was hurt and no property was damaged aside from my own, I nodded off in a curve and woke up just in time to watch my driver's side front wheel smash into the curb. Fortunately I can only assume my foot had come off the gas because I wasn't going fast enough to do much more than road rash the hell out of the lip on my rim. On the down side it knocked my alignment out and when I took it in to get aligned my shop told me A my car is too low to guarantee any work they do on it and B as low as my car is they feel I need a set of tie rod extenders to straighten out my tie rods. I've heard of using these on Miatas and Rhinos but this seems a little odd considering when I got the tires rotated and got everything aligned a month or so ago there was no mention of this.

They are probably referring to a bump steer kit. UPR and Maximum Motorsports sell them. On lowered cars, you ruin the stock geometry of the suspension components. Bumpsteer kits change the relationship of the tie rods so your suspension can function as it was designed from the factory. You may also want to consider a set of caster/camber plates from Maximum Motorsports. They will give the alignment shop much more flexibility in aligning your car correctly.

Both the CC plates and the bumpsteer kits are fairly popular mods, and definitely improve the handling ability of a lowered car.

 

[tikibeast]

They are probably referring to a bump steer kit. UPR and Maximum Motorsports sell them. On lowered cars, you ruin the stock geometry of the suspension components. Bumpsteer kits change the relationship of the tie rods so your suspension can function as it was designed from the factory. You may also want to consider a set of caster/camber plates from Maximum Motorsports. They will give the alignment shop much more flexibility in aligning your car correctly.

Both the CC plates and the bumpsteer kits are fairly popular mods, and definitely improve the handling ability of a lowered car.

I've got the MM C/C plates installed, problem is the "gentleman" I purchased her from had a bit of a fender bender and damaged the driver's side plate and from a visual inspection I'm under the assumption that I may as well leave the plates alone and avoid replacing them until I can get her to a body shop and get the frame straightened a bit.

 

[tikibeast]

So I wandered around over at UPR and MM for a bit and it's looking like UPR is a little cheaper but there are two separate bumpsteer kits and aside from the price and the name the only difference I can see here is one requires spindle modification and one kit doesn't. Before I place an order and find myself stuck with the wrong kit I figure I'd post links and lets some more experienced people eyeball the two kits and chime in.

Requires spindle modification
94-04 Mustang Maximum Power Bumpsteer Kit

Does not require spindle modification
94-04 Mustang Extreme Bumpsteer Kit

 

[flstang65]

I'd go with the second ones. I have used them and they work really well. When they say 30 minute installation, that's right about what it took me to install them (with a lift).

 

[trinity_gt]

FWIW, I wouldn't get any of the currently available bump-steer correction kits for a daily driver. I personally don't care for the un-lubricated, exposed-to-the-elements spherical joint they use and the mechanical "extension" from the spindle to the tie rod gives me the creeps. You're adding a moment arm to the end of the tie rod and, if I were a mechanical engineer that designed it, I wouldn't sleep at night.

Bump steer correction kits are required if you find the suspension behavior objectionable over bumps. Because the car is lowered, the steering rack -- mounted to the chassis -- is physically lower, causing the tie rods to angle upwards to their mounting points on the spindles. As the suspension cycles through its range of motion, the tie rod follows an exaggerated arc, pulling the wheel inward which gives the car a feeling of moving around on the road over bumps and the like. Hence the term "bump steer."

Give the mechanically eerie solutions offered right now I would live with the bump steer and enjoy the engineering of OE steering mounting hardware and ball-joints. There's no reason toe cannot be adjusted even with the tie-rods at a sub-optimal angle due to lowering. The only issue you'd have is out on the road with a potentially darty feel over some bumps.

Find another shop -- preferrably a Mustang tuner -- to do the alignment and leave the bump steer kit on the shelf.

IMHO. YMMV.

 

[Flghtmstr1]

I agree in part with trinity gt above; you don't need a bump steer kit. My car has been lowered for years with Ford C-Springs (which lower the car about 1.5"), and I've never had any problems with bump steer.

However, his explanation is, at best, incomplete. The reason you don't need a bump steer kit is because you still have the factory suspension geometry (well, you did until you crashed, anyway). Think about it: if you didn't change any "hard parts" in the front suspension, then the A-arms are still traveling through the same arcs they always have. You only need a bump steer kit if you relocate the steering rack (as with certain aftermarket k-members), or otherwise alter the relationship between the rack and the spindle.

I agree 100% with his assessment of the safety of those aftermarket bump steer kits. They always gave me the creeps, too.

What you need to do is take your car to a competent alignment shop and have them check the frame for straightness. Also make sure they check that the k-member is in good shape, and is square with the frame. Finally, make sure the a-arms, tie rods, tie rod ends, and ball joints are all in good shape and aren't bent or damaged.

If everything checks out, have them align your car to the following specs: 4.5 degrees caster, -0.5 degrees camber, 0.5 degrees toe-in. These are Maximum Motorsports' recommended figures for street-driven cars, and will provide a stable, bump-steer-free ride, with a great on-center feel, great handling, and good tire wear characteristics.

 

[trinity_gt]

Think about it: if you didn't change any "hard parts" in the front suspension, then the A-arms are still traveling through the same arcs they always have.

With all due respect, no, they're not. For the A-arms, the pivot point has been moved lower by whatever your lowering is -- 1.5- or 2-inches, for example. The A-arms are thus already part-way through an arc that would normally have taken 2" of wheel jounce to get. And at full suspension travel, the arc will have gone that much further depending on how the bump stop is adjusted.

As for the tie rods, the really important thing here, think about the car with an untouched factory suspension sitting on the road. If you look under that car you'll see that the tie rods are, for all intents, parallel to the ground and level with the tie rod mounting bosses on the spindles. This is the most "neutral" position the suspension will take. Up and down suspension movements from this posture generate the least "steer effect" because the arc angles are minimized.

When you lower the car, the rack drops (with the K-member) but the tie rod outer ball joints remain at the same position, bolted to the spindle bosses. The tie rods are now partially arced "upwards". If the suspension is now cycled through its range of motion, on the jounce (upward movement of the wheel) the already-angled tie rods will attain an angle even more severe and will tend to toe the wheel(s) inward moreso than if the tie rods had started out level.

The whole idea of these kits is to lower the outer ball joints of the tie rods to the same level as the steering rack to get back to that neutral, level posture while static.

You only need a bump steer kit if you relocate the steering rack (as with certain aftermarket k-members), or otherwise alter the relationship between the rack and the spindle.

When you lower the car inches this is exactly what you are doing. The rack is bolted to the K-member which drops 1.5- or 2-inches (or whatever). However, the mounting bosses on the spindles do not drop at all. You are effectively relocating the steering rack by virtue of having lowered the body of the car -- all sprung mass including the K-member and everything bolted to it -- with coils.

 

[Flghtmstr1]

With all due respect, no, they're not. For the A-arms, the pivot point has been moved lower by whatever your lowering is -- 1.5- or 2-inches, for example. The A-arms are thus already part-way through an arc that would normally have taken 2" of wheel jounce to get. And at full suspension travel, the arc will have gone that much further depending on how the bump stop is adjusted.

Yes, but it's the same arc. If it didn't bump steer when stock, it won't when lowered. Again, think about it. When stock, it is possible to hit the bump stops when going over bumps, yet nobody complains about bump steer then. When people are lowered, they start having "bump steer" issues as a result of having an improper alignment.

As for the tie rods, the really important thing here, think about the car with an untouched factory suspension sitting on the road. If you look under that car you'll see that the tie rods are, for all intents, parallel to the ground and level with the tie rod mounting bosses on the spindles. This is the most "neutral" position the suspension will take. Up and down suspension movements from this posture generate the least "steer effect" because the arc angles are minimized.

The tie rods do not have to be parallel with the ground. They do have to be parallel to the a-arms, however (or at least as close as possible). Again, with factory "hard parts", the relationship between the rack, a-arms, tie rods, and spindles will not change when the car is lowered.

Look, I'm not trying to say that a lowered Mustang won't bump steer, because it will. Bump steer is an inevitable, unfortunate byproduct of a MacPherson strut suspension. What I am saying is that if you are just installing the typical springs, shocks, and struts to lower your car an inch or two, you do not need a bump steer kit. The alignment specs I gave in my last post will help minimize the effects of bump steer on a street car.

If you don't believe me, call Maximum Motorsports. They'll tell you the same thing. But I don't really know why we're arguing about this, because we both agree that a bump steer kit on a daily-driven street car is unwise, anyway.

Cheers!

 

[tikibeast]

Ok so basically we're all mostly agreed on no bump steer kit. Works for me, that's an extra $100+ that I can put in the PI savings account.

 

[N8Dogg98]

Yes, but it's the same arc. If it didn't bump steer when stock, it won't when lowered. Again, think about it. When stock, it is possible to hit the bump stops when going over bumps, yet nobody complains about bump steer then. When people are lowered, they start having "bump steer" issues as a result of having an improper alignment.

The a-arms are moving on the same arc, but here's the difference. If you are in a Mustang with stock suspension, are turning, and you hit a bump that pushes the a-arm up 2" you won't see much if any bumpsteer effect.

Now same situation, but with a car that has been lowered 2". Again you are turning and hit the same bump pushing the a-arm up 2". Now, the a-arm is up 4" from the factory rest position which dramatically throws off the geometry of the tie rod.

 

[trinity_gt]

I really want to avoid getting into a back and forth internet pissing contest on this so I'll sign off with this and be done with this.

If you're familiar with mathematics, think about the geometry involved in terms of a Cartesian coordinate system.

In this system, a point in the plane can be described by 'x' and 'y' coordinates. A line from the origin of radius 'r' has its end point described by:

x = r cos (ø)
y = r sin (ø)

So picture the tie rod pivot point at the rack as the origin of this plane. The length from this origin to the ball joint on the spindle is 'r'. The terms x and y describe the position of the outer ball joint in the plane relative to the pivot point on the rack. The angle ø is the angle off horizontal of the tie rod.

If you were to disconnect the tie rod outer ball joint from the spindle and swing it up to its range of motion upper limit you would find that while 'r' does not change, x and y do. The x coordinate of the ball joint -- projected down to the x axis -- decreases as the angle ø increases: a plumb bob on the outer ball joint hanging to the ground would move inward toward the center of the car as the tie rod is swung upward.

The key thing to note though is that because the x coordinate is based on the cosine of the angle of the tie rod, the amount the x coordinate moves is not linear as the angle of the tie rod. For example, assume 'r' is 15-inches. For an angle ø of 0-degrees (horizontal), x sits at 15*cos(0) or 15". If the tie rod is moved upward to an angle of 10-degrees, x now moves inward: x = 15*cos(10) or 14.772". This is a difference of ~0.228" and is a decent approximation of how much the wheel will be toed in when the suspension deflects enough to give a 10-degree tie rod angle. Given that toe angles are typically measured in 16ths or less, 4/16ths of an inch is actually fairly substantial.

But what if the tie rod is already at, say, 20-degrees due to a suspension drop and that same 10-degree suspension transit is performed. At the start, x with no additional suspension drop is 15*cos(20) or 14.095". (NOTE: This, of course, would require a lengthening of the tie rod via adjustment to bring the static toe back into spec. This results in a larger 'r' but I'm ignoring that for the moment.) Apply 10-degrees more upward movement and x drops to 15*cos(30) or 12.99" This is a difference now of 1.105" or nearly 18/16", more than 4x more than the previous example. So the wheel is toed in over an inch during this suspension movement on the lowered car versus just under 1/4" for the unlowered car. This is definitely going to feel like **** on the road.

So the same 10-degree absolute angular change brought by suspension movement results in drastically more toe if the tie rod is already angled. This is, of course, because the derivative (rate of change) of x as you move in fixed ø increments around a circle increases as you increase from 0 to 90-degrees. It's easy to conceptualize this or draw a circle and play with a protractor and a ruler...

Bringing the tie rod angle back to close to zero is critical for minimizing the cosine effects described above. That's what these kits are intended to do.

 

[N8Dogg98]

I really want to avoid getting into a back and forth internet pissing contest on this so I'll sign off with this and be done with this.

If you're familiar with mathematics, think about the geometry involved in terms of a Cartesian coordinate system.

In this system, a point in the plane can be described by 'x' and 'y' coordinates. A line from the origin of radius 'r' has its end point described by:

x = r cos (ø)
y = r sin (ø)

So picture the tie rod pivot point at the rack as the origin of this plane. The length from this origin to the ball joint on the spindle is 'r'. The terms x and y describe the position of the outer ball joint in the plane relative to the pivot point on the rack. The angle ø is the angle off horizontal of the tie rod.

If you were to disconnect the tie rod outer ball joint from the spindle and swing it up to its range of motion upper limit you would find that while 'r' does not change, x and y do. The x coordinate of the ball joint -- projected down to the x axis -- decreases as the angle ø increases: a plumb bob on the outer ball joint hanging to the ground would move inward toward the center of the car as the tie rod is swung upward.

The key thing to note though is that because the x coordinate is based on the cosine of the angle of the tie rod, the amount the x coordinate moves is not linear as the angle of the tie rod. For example, assume 'r' is 15-inches. For an angle ø of 0-degrees (horizontal), x sits at 15*cos(0) or 15". If the tie rod is moved upward to an angle of 10-degrees, x now moves inward: x = 15*cos(10) or 14.772". This is a difference of ~0.228" and is a decent approximation of how much the wheel will be toed in when the suspension deflects enough to give a 10-degree tie rod angle. Given that toe angles are typically measured in 16ths or less, 4/16ths of an inch is actually fairly substantial.

But what if the tie rod is already at, say, 20-degrees due to a suspension drop and that same 10-degree suspension transit is performed. At the start, x with no additional suspension drop is 15*cos(20) or 14.095". (NOTE: This, of course, would require a lengthening of the tie rod via adjustment to bring the static toe back into spec. This results in a larger 'r' but I'm ignoring that for the moment.) Apply 10-degrees more upward movement and x drops to 15*cos(30) or 12.99" This is a difference now of 1.105" or nearly 18/16", more than 4x more than the previous example. So the wheel is toed in over an inch during this suspension movement on the lowered car versus just under 1/4" for the unlowered car. This is definitely going to feel like **** on the road.

So the same 10-degree absolute angular change brought by suspension movement results in drastically more toe if the tie rod is already angled. This is, of course, because the derivative (rate of change) of x as you move in fixed ø increments around a circle increases as you increase from 0 to 90-degrees. It's easy to conceptualize this or draw a circle and play with a protractor and a ruler...

Bringing the tie rod angle back to close to zero is critical for minimizing the cosine effects described above. That's what these kits are intended to do.

+1 /thread

 

[Rusty67]

If that shop is scared to align your car go somewhere else.

One trick I've seen used to get alignment done properly on really lowered cars is to use CC plates and then get some cam bolts for the strut which will allow extra adjustment. You can correct with the CC plates after using the came bolt to move the strut further out. This gives that extra bit of adjustment.

I had a MM bump steer kit on my daily driver for over 30,000 miles before some jackass t-boned me and I never had one bit of problem with them or any extra NVH. I do agree however that they should be greasable.

You may need a new tie rod if you whacked the ball joint out from the impact. I would take it to a good shop and have them examine the rack to make sure the inner and outer rods are still in good working order after the smack.

 

[Flghtmstr1]

I really want to avoid getting into a back and forth internet pissing contest on this so I'll sign off with this and be done with this.

If you're familiar with mathematics, think about the geometry involved in terms of a Cartesian coordinate system.

In this system, a point in the plane can be described by 'x' and 'y' coordinates. A line from the origin of radius 'r' has its end point described by:

x = r cos (ø)
y = r sin (ø)

So picture the tie rod pivot point at the rack as the origin of this plane. The length from this origin to the ball joint on the spindle is 'r'. The terms x and y describe the position of the outer ball joint in the plane relative to the pivot point on the rack. The angle ø is the angle off horizontal of the tie rod.

If you were to disconnect the tie rod outer ball joint from the spindle and swing it up to its range of motion upper limit you would find that while 'r' does not change, x and y do. The x coordinate of the ball joint -- projected down to the x axis -- decreases as the angle ø increases: a plumb bob on the outer ball joint hanging to the ground would move inward toward the center of the car as the tie rod is swung upward.

The key thing to note though is that because the x coordinate is based on the cosine of the angle of the tie rod, the amount the x coordinate moves is not linear as the angle of the tie rod. For example, assume 'r' is 15-inches. For an angle ø of 0-degrees (horizontal), x sits at 15*cos(0) or 15". If the tie rod is moved upward to an angle of 10-degrees, x now moves inward: x = 15*cos(10) or 14.772". This is a difference of ~0.228" and is a decent approximation of how much the wheel will be toed in when the suspension deflects enough to give a 10-degree tie rod angle. Given that toe angles are typically measured in 16ths or less, 4/16ths of an inch is actually fairly substantial.

But what if the tie rod is already at, say, 20-degrees due to a suspension drop and that same 10-degree suspension transit is performed. At the start, x with no additional suspension drop is 15*cos(20) or 14.095". (NOTE: This, of course, would require a lengthening of the tie rod via adjustment to bring the static toe back into spec. This results in a larger 'r' but I'm ignoring that for the moment.) Apply 10-degrees more upward movement and x drops to 15*cos(30) or 12.99" This is a difference now of 1.105" or nearly 18/16", more than 4x more than the previous example. So the wheel is toed in over an inch during this suspension movement on the lowered car versus just under 1/4" for the unlowered car. This is definitely going to feel like **** on the road.

So the same 10-degree absolute angular change brought by suspension movement results in drastically more toe if the tie rod is already angled. This is, of course, because the derivative (rate of change) of x as you move in fixed ø increments around a circle increases as you increase from 0 to 90-degrees. It's easy to conceptualize this or draw a circle and play with a protractor and a ruler...

Bringing the tie rod angle back to close to zero is critical for minimizing the cosine effects described above. That's what these kits are intended to do.

Thank you for typing this out and explaining it. You have convinced me. I should have thought it through more before just parroting what I heard from Maximum Motorsports.

I'm curious as to why they explain it the way they do, though. Perhaps they just want to dissuade customers from putting bumpsteer kits on street cars without diving into the geometry lesson.

Posts like yours are why I love Stangnet.

:SNSign:

 

[SaleenGT2001]

If that shop is scared to align your car go somewhere else.

One trick I've seen used to get alignment done properly on really lowered cars is to use CC plates and then get some cam bolts for the strut which will allow extra adjustment. You can correct with the CC plates after using the came bolt to move the strut further out. This gives that extra bit of adjustment.

I had a MM bump steer kit on my daily driver for over 30,000 miles before some jackass t-boned me and I never had one bit of problem with them or any extra NVH. I do agree however that they should be greasable.

You may need a new tie rod if you whacked the ball joint out from the impact. I would take it to a good shop and have them examine the rack to make sure the inner and outer rods are still in good working order after the smack.

ding ding ding, we have a winner. sounds like some of my advice!

the shop is full of crap and basically they dont know how to align your car so they arent giving a warranty. with the right parts i can align almost ANY lowered car.

get a free alignment check (most shops do this) and post up the specs. i will tell you what needs to be done if anything. also have them check for a bent inner tie rod, the outer usually doesnt bend on our cars.

 

[tikibeast]

ding ding ding, we have a winner. sounds like some of my advice!

the shop is full of crap and basically they dont know how to align your car so they arent giving a warranty. with the right parts i can align almost ANY lowered car.

get a free alignment check (most shops do this) and post up the specs. i will tell you what needs to be done if anything. also have them check for a bent inner tie rod, the outer usually doesnt bend on our cars.

From everything I read here I'm probably just going to take it back to the shop that did my alignment last time, they're a little more expensive, but they knocked it out without any complaints aside from a comment about a damaged CC plate. Thanks for all the input and the math lesson gentlemen.

 

[lang williams]

If after the alignment you have bump steer issues you could also try the off set steering rack bushings. They are pretty cheap an raise the rack to off set some of the drop of the springs. Here's a quick read for some basic info: Late Model Mustang Suspension Basics