Wednesday, January 28, 2015

Informational Series Part 4 Tie Rods

I've talked about knuckles, and I've talked about steering racks, so why not talk about the parts that go in between and connect the two.  I've mentioned them previously and I think it's time to talk about them.  This post will be all about tie rods, both inner and outer.

Like always I want it to be known that I'm going to try keeping this rather simple, so don't treat this as an end all be all post about tie rods.  The point of this is to give you information on them to help you further your understanding of the parts and help you make better decisions with your car.  It's also meant to clear up some confusion and false information out there.

With that all said, lets begin!

Tie rods are broken down into two parts, the inner tie rod or rack end as some call it, and an outer tie rod.  There really isn't much to say when it comes to describing them, the inner is a threaded rod with a joint that screws onto the end of a steering rack and the outer is a joint that bolts to the steering knuckle and screws onto the inner tie rod.  When put together and installed they make up the link between the steering rack and steering arm.  As simple as that.

Now that you know what they are and what they look like lets get to some more in depth details starting with the inner tie rods as these are incredibly simple and there's not a whole lot to say about them.  The jointed end has a threaded portion that acts as a bolt and threads directly into the end of a steering rack.  The base of the joint is usually flat and when turned all the way will bottom out on the end of the rack casing and doesn't go inside of it like an angle spacer does.  Then we have the joint itself, it's a spherical ball joint that's essentially the same as a lower ball joint.  Just a ball that's fixed inside a casing in which it can pivot around.  They are able to move in every direction and can also spin.  On the end of the ball is a rod which also has a threaded end to it.  Tie rods are typically consisting of two parts, the ball casing, and the ball/rod portion. (please note these are not their actual terminology just what I'm referring to them as).

Here is an example showing those two parts that make up a tie rod.  I've coloured the casing green and the rod blue as well as made 3 different views showing how the 2 portions are put together to make up an inner tie rod.  I've also included the jam nut in this drawing which I'll talk about later.

As you can see there isn't much to these, so why are there so many different brands and options available?  Well the big difference and reason why you see people upgrade their inner tie rods is due to the factory ones not being strong enough.  Factory tie rods are designed and meant for commuting, they aren't typically designed to handle extreme loads. On top of that they also are used as a "weak point" in the steering so if a large amount of stress was put on the steering system this is the part that will break first and save the rest of the steering components from suffering damage.  This is a very good thing to have as tie rods are incredibly cheap and are incredibly easy to replace.  I can tell you right now you'll be a lot happier about replacing a tie rod than replacing a steering rack.

Back to upgrading them.  With race use, steering components will see a lot more stress and abuse than they would driving to and from work.  On some cars the factory inner rods were made too weak for this.  The S13 is a good example, they use a very small diameter tie rod from the factory and are notorious for bending or breaking.  This is why stronger ones are needed and are sought after.  A stronger one won't bend or break under the heaver loads that are experience when racing, this keeps the car from breaking and lets you keep driving!  Not all aftermarket tie rods are the same when it comes to strength, they all have different designs and are hardened to different levels as well as variances in the materials themselves.  It's pretty much safe to say that any big name brand tie rod will be plenty strong, and in some cases OEM replacement brands are just as strong as upgraded aftermarket ones.  Take Moog brand tie rods for example, I run a pair of Maxima OEM replacement ones on my car and have never had an issue with them.

So now that we've got the main reason why people upgrade their inners out of the way lets talk about another reason someone might choose to get an aftermarket one.

Some companies have caught on to the benefits of an angle spacer and have began making tie rods that are more suited for their use by adding longer threads to the end or even putting built in angle spacers on the tie rods themselves.  By doing that a person can simply buy new inner tie rods, throw them on with the angle spacers and achieve more steering angle.  

I think this is where some confusion about tie rods has come up.  I've heard a lot of people say "tie rods give you more steering angle".  Saying that isn't exactly right.  The tie rods themselves aren't giving you more angle, its the angle spacers that are.  Saying aftermarket tie rods in general give you more angle is wrong as not all aftermarket ones have built in spacers so those ones wont add any angle at all.  All the angle comes from the spacer and not the tie rod.

The second biggest reason why people change out their inner tie rods is because of length.  A lot of race cars and pretty much every drift car with big angle setups have a widened track (how far away the wheels are from each other).  Drift cars with big angle almost always have to lengthen their control arms in order to move the wheels out further.  This is done to allow more clearance within the wheel well and prevent the tire from rubbing on the frame of the car at high steering angles.  Of course since the control arms have been lengthened this also means the tie rods must be lengthened as well.  This is where you'll see a lot of people swap out tie rods for longer ones as too short of a tie rod won't allow you to set your toe right and your alignment could be off so much that it'll make the car impossible to drive.

One last thing thing to talk about with tie rods is quality.  This is a big one here as not all brands put the same amount of quality into their parts.  When looking at tie rods take this into consideration, if they are super cheap and you're buying some no name replica brand ones off Ebay you might be in for a bad time.  The main area where some companies will cheap out is in their joints, a cheap and poorly designed joint will wear out faster which means you'll be looking at buying the same part twice which in the end will cost you more money than if you just bought a nicer quality part from the start.

All right, it's time for some potential downfalls to take in.  Unlike most parts different inner tie rod designs can't really have any negative effects on your car.  Brand A tie rod compared to brand B won't really make any difference in your cars handling or feel, one will just be nicer than the other or one might have an angle spacer that's built in where the other doesn't.  The only real bad effect you can have from a tie rod comes from it's joint.

Not all joints are the same and not all companies design them the same.  The misalignment angles (angles they are able to move around) that they offer are different between brands.  You almost never have to worry about this but with rare occasions this could be a problem.  There could be one that's designed with very little misalignment built into them so if your suspension travel is extreme enough you could very well have it go past the point of it's misalignment ability and in turn put the weight of the car on your tie rod which will lead to bending or breaking it.  This could be very bad for you because as I'm sure you've figured out, a broken tie rod means you no longer have control of steering your car which could very well cause you to have an accident.

This is something you shouldn't beat yourself up over when looking at tie rods. I can only think of one brand that could potentially have this be an issue and they have it clearly stated on their website as part of the description of their tie rods.  On top of that the misalignment amount theirs still offers is more than enough for your normal setup, most cars don't have enough travel in their suspension.  The only people who should be concerned about this are cars that are lowered an extreme amount and don't have any supported modifications to correct it from being an issue.  The opposite as well, cars that are raised an extreme amount also face this as being an issue.  Then there's cars with extreme suspension travel, and I mean extreme amounts of travel!

That should cover inner tie rods so lets move on to outer tie rods.

There are many different style of outer tie rods, the two above are the ones I will be referring to as they are what you'll see used almost all of the time.  The one is your basic factory style outer tie rod where the other is your common aftermarket style.

Your factory rod will usually consist of two major parts.  The rod/casing and the joint/shank as pictured above, there's also a shank nut as well.  For aftermarket ones however they are usually broken down a little bit more.  For these the rod and casing aren't one piece and neither is the joint and shank.  Instead there is a threaded hex rod, spherical rod end, rod end jam nut, shank, both a bottom and top nut for the shank, and bump steer spacers.  Keep in mind both styles also use a jam nut on the inner tie rod which will be tightened against the outer tie rod where it threads into the inner tie rod.  This is used for locking the outer tie rod in place after aligning the car.

There are a few different reasons people change out their outer tie rods.  Strength, adjustability, and sometimes you just don't have a choice and are forced into it.  Again let's take a look at an S13 for an example.  As mentioned earlier their inner tie rods are of a very small diameter and when upgrading the aftermarket ones are larger, because of this they have a larger diameter thread on the end.  This means the factory S13 outer tie rods are no longer able to thread onto the new inners and you're forced with buying different outer tie rods.  Luckily for the S13 this is as easy as buying the later generation S14 or S15 model tie rods.  Some other cars might not have this choice and be forced to go all aftermarket.

Lets talk about strength, like before, sometimes the OEM outer tie rods aren't all that strong.  I can't think of any car to use for an example on this one as every one I have experience with has had very strong factory outer tie rods that aren't a problem.

The main reason you'll see people go aftermarket is for the adjustablility they offer.  Not just for toe but for bump steer as well.  Bump steer being the main reason to get them and also the most misused steering part I've seen on a lot of cars.  I'm not going to go in depth with bump steer on this post, it'll be a topic I'll cover later on.  It's one of the most misunderstood things I've seen throughout the grassroot community and if you've got some on your car and simply just set them at the lowest setting thinking that it's how you get rid of bump steer you've probably just created a serious bump steer problem because of it.  How the adjustments work is like this.  Generally on rear steer cars adjusting your bump steer down adds toe in under compression, adjusting upwards adds toe out under compression.  On front steer cars it's the opposite so adjusting down adds toe out and adjusting up adds toe in.  Of course it doesn't always work out that way as there are a lot more factors than this that effect your bump steer, but this is the general effects that it has.  The goal of adjusting is to find that happy medium so it doesn't add toe in or toe out, or at least reduce the effect to be as minimal as possible.

Each different brand outer tie rod will all have their pros and cons.  Things to look at is adjustability, quality, size, and length, along with some other aspects.

Speaking of this, lets take a look back at the "tie rods add angle" comments people have said.  Here's another area in which they have caused some confusion.  The actual size of the tie rods themselves can play a roll here.  On some cars the outer tie rod is what makes contact with the steering bump stop, on cars where this is the case, the size of an outer tie rod can effect at what angle the steering will reach it's bump stop.  A larger tie rod will hit the bump stop before a smaller one will.  A smaller tie rod adds more clearance and thus allows for more angle to be achieved but it should be noted that the tie rod isn't actually adding any angle, just offering clearance to allow for it.

Here is a quick comparison of two different sizes.  You'll notices when talking about size in this situation we will be working from a top view.

Above I've drawn a quick example of how a tie rods size can affect the overall steering angle.  For the example the "bump stop" is the lower control arm itself like it is on an s-chassis.  The top example has a smaller outer tie rod where as the bottom one is larger.  Instead of drawing a steering arm I've simply replaced it with a line.  The point of contact for the outer tie rods has been placed in the same position as well.  After the lines were made I copied them and set the two on top of each other to show the difference in angle that was created.  It's not a super crazy amount of a difference but there is a difference.  Also, keep in mind none of these drawings are to scale and the difference on an actual car is usually much less than this.  I did a rather extreme example so the difference would be more visible.  Another thing to note about this is if your tie rods aren't even reaching the bump stop then size of course wouldn't change anything at all.  A lot of times you'll see the steering rack bottom out before the tie rod will reach the bump stop.

Time to move on to the "cons" portion of these.  Just like inner tie rods there aren't really any cons to talk about.  Doesn't matter what design you have be it an oem ball joint style outer tie rod or an aftermarket spherical rod end style outer tie rod.  If they are both set at the same bump setting neither will have an effect on how the car drives.  You could argue weight or the amount of friction the joints have as potential cons but those differences are so minimal you're not even going to know there's a difference going on.

So instead lets talk about potential problems you could run into.

Like inner tie rods outer tie rods also have the potential to have some misalignment issues with its joints.  Unlike inner tie rods this is something I've not only seen but have personally experienced with a pair I ran on my car.  Outer joints experience a lot more misalignment changes than inner tie rods, when turning they can experience a good amount of change and on top of that its also when you'll see the most amount of suspension compression occur when hitting a bump.  This means there's a very good chance you might just find yourself in a situation where you max out your outer tie rods misalignment angle.

What happens when this occurs?  You guessed it, you run into some problems.  How much damage that happens has a lot of factors but you're going to run into one of these things.  The most common one being bending or snapping an inner tie rod.  Other problems are bending or breaking the the bump steer correction shank, breaking a steering arm, or breaking or causing serious damage to the outer tie rod joint itself.  This could potentially be a serious problem to have happen, as you know what happens when a steering component like this breaks.  You lose control of your steering and you run an incredibly high risk of wrecking.

With all of that said make sure you pay attention to these things when looking at purchasing some outer tie rods.  For pretty much every car the factory outer tie rods are a good choice and are sometimes even a better choice than some aftermarket ones I've seen.  One thing I always recommend is if you don't know what you're doing when it comes to setting your bump steer you're probably better of with using the factory ones.   If you don't know what you're doing when making changes to your car there's a good chance you could wind up making changes that cause your car to drive worse than if you had just left it how it was.

For this this post I've also decided I'm going to add an extra portion which I will not normally do.  This portion I'm going to talk about installation of the parts as I've seen waaaaaaay to many tie rods installed incorrectly and doing so puts those drivers at risk and the people around them at risk as well.  I would really hate to see an accident occur because of an incompetent person installing parts wrong.  A lot of parts come with installation instructions, I don't give a crap about how smart you think you are, read the damn things before putting them on.  If yours didn't come with instructions use Google, you can find what you're looking for by just searching.  Worst case if you can't find the answer, reach out to someone who has some experience and has the knowledge to properly help you.

Installing inner tie rods is simple, don't double up angle spacers.  Run one spacer.  Always use some thread locker, ALWAYS!  You don't ever want these to find a way of coming loose!  Another thing, get the right length tie rod, if yours is too short get a longer one.  If its too long you can almost always trim it down to be the right size. In fact I recommend buying ever so slightly long ones on purpose, this way you can ensure the inner tie rod has as many threads as possible going into your outer tie rod.  Figuring out what length of tie rods you need is as easy as grabbing a tape measure and putting it to use.

Outer tie rod time.  First of all, always make sure you put the jam nut on the inner tie rod.  Without a jam nut your alignment can change while driving, so always make sure there's one on there.  On the shank that bolts to the steering arm, always use a pin on the castle nut, and if you've got one that doesn't use a pin, use a nylon locking nut or some thread locker.

Now for the big one.  This is the one I've seen installed wrong more times than I can count.  With aftermarket outer tie rods that use a spherical rod end that bolts onto a hex rod.  ALWAYS use the jam nut on it and thread the rod end into the hex rod the proper amount.  For this you'll want to check with the manufacturer for a recommended amount.  Too little of threads in the hex could result in pulling the rod end out of the threads.  If you're unsure about how much is needed it's always a safe bet to thread the rod end in as far as possible to avoid any problems.

This should cover pretty much everything you need to know for now.  Hope you enjoyed reading it, possibly learned something new, and that this might have even helped you with your decision on what tie rods are right for you.

I'll see you guys next post!

1 comment:

  1. Great informations and great job! Thank you for your time and for sharing! Cheers mate!