Strut Bar – Explained

Strut Bar – Explained

Hello everyone and welcome to this week’s video. Today I’m going to be explaining
strut bars and the purpose of strut bars. Now, essentially strut bars are
used to increase the rigidity of a car, for when you’re cornering or
if you hit bump or something like that, you’re gonna increase the rigidity of your car and basically it’s going to make it a bit more predictable, give it a little bit better handling so that
there’s not flex in your chassis when you hit a bump or something
like that or you’re going to a hard corner. Now, these particular strut bars that I’m going to
use in this video are courtesy of I’m gonna have a product link and a link
to in the description, so if you’d like to check that out, feel free. So let’s take a look at first of all
where these will be installed. Okay, so here we have the engine bay. Basically,
if you just follow the tires directly up, you can get to your strut towers. So there’s the front right strut tower and
here is the front left strut tower. And what we’re essentially going
to do is connect those two. Ok, so now that we understand where these
strut bars are going to be installed, connecting the two strut towers, let’s take a look and kind of analyze the forces that are going on. So I’ve got two different suspensions
setups here, one is Mac Pherson Strut, which is basically why strut bars are created. Mac Pherson Struts are load bearing at the top
whereas double wishbones aren’t really where the— the coilover connects. So I’ve got a double wishbone here and a
Mac Pherson Strut here and I’m going to talk about some of the forces involved. So first of all we’re going to pretend that we’re looking at the back of the car and it’s going around a corner— we’ll say it’s going it’s going to be taking a hard right corner, and so, what’s going to happen is the car is going to want to go to the left,
but friction is going to push the car and allow it to maintain that corner and not slide. So this is your friction force here coming in
from the road and here’s your tire. So that friction force—here we’ve got our lower control arm and the friction force is going to want to rotate this tire kind of down towards the ground
about this point of your lower control arm. So it’s going to create a moment about this
control arm and when it does that, it’s going to be pulling this tire kind of down like that and it’s gonna be pulling on the upper strut, where that strut connects with the body of the car.
So this right here is the body of the car and then this is where your strut connects, so it’s going to be
pulling—there’s going to be a force pulling on that. So that strut reaction force is what—basically, if you don’t have a strut bar—you’re just going to have the body of the car, which is going to be the reaction force.
If you do have the strut bar, you’re going to be using both sides—both towers of the car and that force is going to pass along here and both of these towers are going to take that force, opposing the friction. So, once that has been kind of
cancelled out by the two towers rather than one, you’re going to have less
flex going on in the body of the car. Now, if the other setup is a double wishbone
suspension—so here we gonna have the car going in a different turn. So now it’s going to be taking a left hand turn and so we’re going to have a friction force coming in because the car wants to slide out but friction is
going to prevent it, and so it’s gonna push this way. That’s going to cause a moment, created about this lower control arm, and in order to counter that moment, there’s going to have to be a force—a reaction force in the upper control arm which is countering it. So, basically, here what we’ve got going on:
this strut reaction force is going to cancel out that moment there, whereas on the double wishbone suspension, this upper control arm force is going to counteract that moment
created at the lower control arm. So that’s going to basically take on the
forces from the G-force—the lateral forces are all can be absorbed within this suspension setup, which is one of the advantages of
a double wishbone suspension. so that said, a strut bar will play a bigger
role with a Mac Pherson Strut vehicle. Now, for example with my car, this strut bars are
for an Accura Integra and the base Integra does not come with strut bars. However, the GSR or the type-R Integra
do come with the strut bar, even though it’s a double wishbone suspension. So why might you want a strut bar even if
you do have a double wishbone suspension? Well, as the car leans in cornering, it’s going to
compress that spring and so you’re gonna have— as the weight transfers over and the body rolls,
It’s gonna compress this spring and you’re going to have a vertical force
pressing on the body of the car. So by connecting that you can kind of
transfer this force across the strut bar and allow both sides of the car to take on that force. Also, if you hit a bump, you’re going to have very large vertical force, and that’s all going to go to that one single strut tower, and so if you’ve connected your strut bars, some of that—the horizontal component of that force will pass over and you can absorb
the force with both sides of the strut tower. So, as I was saying, that’s why
on a type-R it comes standard. In quite a few cars out there it comes standard. Also, in the rear you can apply the same principles, whether this is in the front of the car or the rear of the car. I believe the JDM Accurate Integra type-R did
come standard with a strut bar in the back. So we can take a bit more
detailed look at these strut bars. In the front, this is the front strut
bar and this is the rear strut bar. So basically one thing to keep in mind is a strut bar is only a strong as its weakest component, So, for example, these are some high-strength bolts here, since there’s going have a shear force. And then you’ve got this thick
metal here to pass that force along. So thanks for watching. If you have any questions or comments, feel free to leave them below. And don’t forget to check out

About the Author: Michael Flood


  1. Reason why the Integra and civic s with the double wish bone front suspension benefit from a tower brace is because the front upper A-arms bolt on to the towers so high that they essentially exert the same force a MacPherson strut does on to the towers.

  2. There should've been more emphasis that a solid piece bar is far more rigid than one with pivoting bolts. Much more thought has to go into a solid one-piece bar as it must be custom made, vs parts-bin approach for screw-out bars with pivoting bolts attached

  3. i got a founders performance "shock" tower bar (no struts on a 98 firebird) for 3 reasons… 1- every lil bit helps, 2-it looks cool, & 3-it gives me a place to grab/lean when workin under the hood (& thats honestly the main reason i say money well spent)

  4. Thank you so much for these video's! My textbook methods are terrible.. I just watch your video's to understand what I'm supposed to learn 😀

  5. adding a strut bar in the rear of a fwd car with double wishbone suspension will increase the chance of oversteering and decrease the chance of understeering?

  6. You forgot to mention the most important fact about the strut bar: Only the solid welded in is worth doing. These adjustable with many moving parts simply doesn't make any sense because they are not functional. You should know that! But then your sponsors wouldn't be happy about it…

  7. Your freebody diagram is wrong. You do not have any moments on the lower control arms. They are pin connected so they can't transmit moments.

  8. Don't think the ITR came stock with a rear strut bar.
    How about a roll cage?! That's adds a lot of torsional stiffness right?

  9. My vw has a cover over the engine bay does this mean if I wanted to added a strut bar would I have to take the cover off in order to have the strut bar?

  10. Great Information! Thank you for explaining to me this strut bar concept. On a Challenger 392 should I go with putting the bar in the front of the engine?

  11. i say its worth the price i paid (founders-cost $45) for a place to grab & prop urself up while leaning under the hood on my formula

  12. What are your thoughts on installing a strut bar on an RD1 CRV for off road purposes, to improve torsional rigidity of the chassis?

  13. I moved from a 2014 accord saloon to a 2017 accord coupe which is basically the same car with 2 doors less. But the handling of these 2 cars is way different. I guess part of it could be because of the strut bars and part of it could be because of the rigidity of the coupe body type.

  14. I saw a video of a manager (?) at a (4 wheel shock?) testing facility that said, "no aftermarket strut bar has ever improved structural rigidity". It didn't look like their test equipment was able to apply any simulated lateral (friction-type) loads, but I'm not sure.
    Anyone have thoughts on this ?

  15. Hey man , have a small question. Will using a better made tyre with same dimensions aid in lowering down body roll.
    Will better tyres affect body roll ?

  16. PS one thing if the left wheel has its friction going to the left while cornering right, than the right wheel has the same. Does that mean the rights strut also want to lean to the left?

  17. Hi, what would be the impact of strut bars in relation to fuel economy in city and highway driving? Considering bumps and holes on the roads. Thank you!

  18. I don't know, I don't think most strut bars do anything besides a placebo affect. That cap-head bolt only supports a moment about the axis of the strut bar, that stand-off mount give that rear bar a nice parallelogram effect, and the jam nut is just silly. I think the only strut bar worth buying is a static, non-generic bar that is specifically made for your vehicle and has welded joints instead of all the bolt/cantilever joints on the bars in this video.

  19. It's no use, they still don't get it. Their minds are polluted by auto forum mods who don't allow them to think for themselves.

  20. I'm planning on adding this to make it more stiffer at the front and I'm not sure if the same type strut bar can fit on the back suspesion coilover spring thing it's a sedan I'm talking about

  21. I found it strange the bar itself was thick, made to prod an elephant but was expected to transfer ALL that inertia force thru it and into a small 1/4" bolt?  Just sayin..

  22. Hate it when I get flex in my chassis. Accidentally did that at the gym and I been flat on my ass for the past 2 days.

  23. 2019 Honda civic type R. You drove this Type R and do you think other 10th Type R owners will enjoy better handling experience putting both front and rear strut bars? Please advise with your expert opinion. Thanks. By the way, I do enjoy your channels. Cheers.

  24. So a really they are hinged as they are more about transfer of horizontal force than acting as a true solid component to the chassis?

  25. Does strut bars effect comfort of the car as the force gets transferred from one side to another while hitring bumps? Is it OK & good to use strut bar in a bumpy road or is it meant for a flat carpeted road?

  26. Ok. Ok. Thank you very much for this post! Until today, I had no idea what a strut bar was or what it did. We have a PT Cruiser and the previous owner installed a strut bar (Alutec UltraStrut) that is welded right beside the strut bolts, as you indicated. My problem is it goes directly over the power steering reservoir which means I can't open that reservoir to check it. It almost blocks the coolant reservoir ▬ but at least I can open that one.

  27. I have a 2017 Subaru Forester XT. The rear sway bar did make the car feel more planted around corners (it's a 20 mm vs 16 stock). Would a front strut bar help my car at all feel a bit more planted and less rolling/yaw? Anyone try it?

  28. Can you explain what about the rear strut bars? Suppose the front will affect the handling …. How about the rears? Also, is it dangerous to only insert front strut bars not rears? Furthermore, there are upper strut bars and bottom strut bars. Do they serve the same function and purpose?

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