Chassis bracing questions; sharing loads and increasing understeer?
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Chassis bracing questions; sharing loads and increasing understeer?
2006 Civic Si Coupe, no suspension modifications.
I have purchased but yet to install the Progress rear sway bar. There are numerous reports of endlink brackets breaking under hard cornering forces, so I'm a little wary.
Will a rear lower tie bar share the load with the sway bar? I am looking for anything that will help in preventing the endlink brackets from snapping.
Also, will adding a front tower strut bar increase the understeer on a FWD car? From my limited knowledge of suspension dynamics, I feel that adding stiffness to the front won't be desirable, at least without compensating in the rear as well.
Thanks for any input.
Modified by televascular at 12:51 PM 4/18/2008
I have purchased but yet to install the Progress rear sway bar. There are numerous reports of endlink brackets breaking under hard cornering forces, so I'm a little wary.
Will a rear lower tie bar share the load with the sway bar? I am looking for anything that will help in preventing the endlink brackets from snapping.
Also, will adding a front tower strut bar increase the understeer on a FWD car? From my limited knowledge of suspension dynamics, I feel that adding stiffness to the front won't be desirable, at least without compensating in the rear as well.
Thanks for any input.
Modified by televascular at 12:51 PM 4/18/2008
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From: strathcedar, nsw, australia
Re: Chassis bracing questions; sharing loads and increasing understeer? (televascular)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by televascular »</TD></TR><TR><TD CLASS="quote"> Will a rear lower tie bar share the load with the sway bar? I am looking for anything that will help in preventing the endlink brackets from snapping.</TD></TR></TABLE>
I can't see a 'tie-bar' having any affect on taking load off the rear ARB or it's linkages. If the endlink brackets on your car model are weak then that's what will need to be re-inforced.
I'm not sure what the brackets on various Civics are like, but I do know the endlink brackets (that attach the ARB links to the suspension radius rods / trailing arms) on the rear ARB on CB7 / CD5 Accords are quite flimsy, and while I haven't heard of them breaking they do flex quite a lot. Such bracket flexure effectively deducts stiffness from the rear ARB and makes it behave as if it were less stiff than it actually is (the affect is somewhat like would be the case with very soft ARB mounting bushes).
Anything you can do to stiffen the rear ARB attachment brackets (on the suspension <U>and</U> chassis) is likely to be a good thing. CB7 / CD5 Accords suffer from soft / flexible rear ARB mounting brackets on both the chassis and suspension (Civics may be similar?), stiffening these up on my Accord made a noticable difference to reduction in understeer.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by televascular »</TD></TR><TR><TD CLASS="quote">Also, will adding a front tower strut bar increase the understeer on a FWD car? From my limited knowledge of suspension dynamics, I feel that adding stiffness to the front won't be desirable, at least without compensating in the rear as well. </TD></TR></TABLE>
In theory yes it should to some slight degree, in practice it may not to any noticable degree. I have a very robust (home made) front tower brace fitted to my CB7 and didn't notice any significant increase in understeer when I fitted this, but did ntice a significant improvement in steering response and a sensation of chassis 'tightness' (not as in 'understeer').
It's hard to explain, but it feels like the tower brace assists the chassis to be more effectively connected to the suspension and is connecting the suspension at each corner to the suspension at the other corners. You can actually feel this if the tower brace is a good / rigid brace, but probably not with a cheap / flexible brace (more $ may not mean more stiffer though...).
Even if the tower brace did cause a slightly noticable increase in understeer (which it didn't on my car) I'd still fit it beause of this feeling of 'structural integrity' that it gives to the chassis. I'd also recommend a rear tower brace, definitely worthwhile.
I can't see a 'tie-bar' having any affect on taking load off the rear ARB or it's linkages. If the endlink brackets on your car model are weak then that's what will need to be re-inforced.
I'm not sure what the brackets on various Civics are like, but I do know the endlink brackets (that attach the ARB links to the suspension radius rods / trailing arms) on the rear ARB on CB7 / CD5 Accords are quite flimsy, and while I haven't heard of them breaking they do flex quite a lot. Such bracket flexure effectively deducts stiffness from the rear ARB and makes it behave as if it were less stiff than it actually is (the affect is somewhat like would be the case with very soft ARB mounting bushes).
Anything you can do to stiffen the rear ARB attachment brackets (on the suspension <U>and</U> chassis) is likely to be a good thing. CB7 / CD5 Accords suffer from soft / flexible rear ARB mounting brackets on both the chassis and suspension (Civics may be similar?), stiffening these up on my Accord made a noticable difference to reduction in understeer.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by televascular »</TD></TR><TR><TD CLASS="quote">Also, will adding a front tower strut bar increase the understeer on a FWD car? From my limited knowledge of suspension dynamics, I feel that adding stiffness to the front won't be desirable, at least without compensating in the rear as well. </TD></TR></TABLE>
In theory yes it should to some slight degree, in practice it may not to any noticable degree. I have a very robust (home made) front tower brace fitted to my CB7 and didn't notice any significant increase in understeer when I fitted this, but did ntice a significant improvement in steering response and a sensation of chassis 'tightness' (not as in 'understeer').
It's hard to explain, but it feels like the tower brace assists the chassis to be more effectively connected to the suspension and is connecting the suspension at each corner to the suspension at the other corners. You can actually feel this if the tower brace is a good / rigid brace, but probably not with a cheap / flexible brace (more $ may not mean more stiffer though...).
Even if the tower brace did cause a slightly noticable increase in understeer (which it didn't on my car) I'd still fit it beause of this feeling of 'structural integrity' that it gives to the chassis. I'd also recommend a rear tower brace, definitely worthwhile.
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From: NJ, USA
Re: Chassis bracing questions; sharing loads and increasing understeer? (johnlear)
Thanks for the input, John.
From the threads I've read, the brackets fail when the endlinks rip through the holes that they're mounted to. I've briefly considered taking my car to a shop to have them weld extra mass onto the brackets to prevent this from happening, but I was hoping a tie bar would add stiffness and share loads at the same time.
A good thing I've discovered, however, is that upgrading the stock endlinks is unnecessary for my car, since they're not the weak link in this scenario.
There are several different braces available for my car (rear/front lower tie bars, rear/front tower braces, underbody H-brace, B-pillar bar), and while I'd like to add stiffness overall, I want to be able to feel the difference with every single mod before adding another. I'm not too keen on a rear tower bar either, since it eats up trunk space.
I guess I'll start with the sway bar and go from there. I will definitely consider the front strut tower bar too, thanks.
From the threads I've read, the brackets fail when the endlinks rip through the holes that they're mounted to. I've briefly considered taking my car to a shop to have them weld extra mass onto the brackets to prevent this from happening, but I was hoping a tie bar would add stiffness and share loads at the same time.
A good thing I've discovered, however, is that upgrading the stock endlinks is unnecessary for my car, since they're not the weak link in this scenario.
There are several different braces available for my car (rear/front lower tie bars, rear/front tower braces, underbody H-brace, B-pillar bar), and while I'd like to add stiffness overall, I want to be able to feel the difference with every single mod before adding another. I'm not too keen on a rear tower bar either, since it eats up trunk space.
I guess I'll start with the sway bar and go from there. I will definitely consider the front strut tower bar too, thanks.
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From: strathcedar, nsw, australia
Re: Chassis bracing questions; sharing loads and increasing understeer? (televascular)
Sounds like your issue is to do with the brackets that attach the ARB to the chassis, or the actual subframe that the brackets attach to, rather than the end-links attachment to the susopension.
When I made / fitted my front tower brace I didn't really expect it to have more than a barely noticable affect (and wouldn't have been surprised if it had no noticable affect). However, I was surprised by how much affect it did actually have, much more noticable than I expected.
Funny thing, you don't really know that your car needs what the tower brace does until you fit the brace! I had a similar experience with the rear tower brace, i.e. didn't expect much from it but pleasantly surprised at how much positive affect it had.
Note that rigidity is the key to a good and effective tower brace, if any part (including the attachment brackets) is not very rigid then it won't work very well. There are a lot of very poor tower braces around (i.e. less than rigid), and a lot of people who think tower braces do nothing. I suspect a connection...
When I made / fitted my front tower brace I didn't really expect it to have more than a barely noticable affect (and wouldn't have been surprised if it had no noticable affect). However, I was surprised by how much affect it did actually have, much more noticable than I expected.
Funny thing, you don't really know that your car needs what the tower brace does until you fit the brace! I had a similar experience with the rear tower brace, i.e. didn't expect much from it but pleasantly surprised at how much positive affect it had.
Note that rigidity is the key to a good and effective tower brace, if any part (including the attachment brackets) is not very rigid then it won't work very well. There are a lot of very poor tower braces around (i.e. less than rigid), and a lot of people who think tower braces do nothing. I suspect a connection...
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Re: Chassis bracing questions; sharing loads and increasing understeer? (televascular)
Speaking of front shock tower braces, I went from the very good Comptech Aluminum brace to the Neuspeed tubular steel brace (don't think it's manufactured anymore), and noticed a huge difference. If there is any way that you can get a brace that has no pivots (or at least uses two bolts for a pivot) then you are going to get the best bang for the buck.
Also, adding braces is probably one of the best mods out there simply because they are cheap (some are easily DIY), and because they have such a large effect on chassis stiffness. Remember, a stock car is just really thin (like less than 1/4") sheet metal all over, if you go to the junkyard and see a cut up Civic you will realize how structurally weak these cars really are.
Also, adding braces is probably one of the best mods out there simply because they are cheap (some are easily DIY), and because they have such a large effect on chassis stiffness. Remember, a stock car is just really thin (like less than 1/4") sheet metal all over, if you go to the junkyard and see a cut up Civic you will realize how structurally weak these cars really are.
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Re: Chassis bracing questions; sharing loads and increasing understeer? (ginsu2k)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ginsu2k »</TD></TR><TR><TD CLASS="quote">Also, adding braces is probably one of the best mods out there simply because they are cheap (some are easily DIY), and because they have such a large effect on chassis stiffness. Remember, a stock car is just really thin (like less than 1/4") sheet metal all over, if you go to the junkyard and see a cut up Civic you will realize how structurally weak these cars really are. </TD></TR></TABLE>
I'm a little more concerned than the average tuner, since I plan on only lightly modding this car and driving it until the wheels fall off. I've read somewhere (on the internet, so, grain of salt and such) that adding structural bracing is great for performance but transfers more stress to the frame and will shorten its life.
Any merit to this statement?
I'm a little more concerned than the average tuner, since I plan on only lightly modding this car and driving it until the wheels fall off. I've read somewhere (on the internet, so, grain of salt and such) that adding structural bracing is great for performance but transfers more stress to the frame and will shorten its life.
Any merit to this statement?
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From: Sherman Oaks, CA, United States
Re: Chassis bracing questions; sharing loads and increasing understeer? (televascular)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by televascular »</TD></TR><TR><TD CLASS="quote">
I'm a little more concerned than the average tuner, since I plan on only lightly modding this car and driving it until the wheels fall off. I've read somewhere (on the internet, so, grain of salt and such) that adding structural bracing is great for performance but transfers more stress to the frame and will shorten its life.
Any merit to this statement?</TD></TR></TABLE>
I fail to see how preventing the frame from bending under loads it would have bent under would shorten its life. If anything, it should extend it.
That said, I also don't think most of the chassis reinforcement bars available for our cars actually do much to prevent anything that would have moved from moving.
All of that is just my opinion. Take it for what its worth.
I'm a little more concerned than the average tuner, since I plan on only lightly modding this car and driving it until the wheels fall off. I've read somewhere (on the internet, so, grain of salt and such) that adding structural bracing is great for performance but transfers more stress to the frame and will shorten its life.
Any merit to this statement?</TD></TR></TABLE>
I fail to see how preventing the frame from bending under loads it would have bent under would shorten its life. If anything, it should extend it.
That said, I also don't think most of the chassis reinforcement bars available for our cars actually do much to prevent anything that would have moved from moving.
All of that is just my opinion. Take it for what its worth.
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From: strathcedar, nsw, australia
Re: Chassis bracing questions; sharing loads and increasing understeer? (TunerN00b)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TunerN00b »</TD></TR><TR><TD CLASS="quote">That said, I also don't think most of the chassis reinforcement bars available for our cars actually do much to prevent anything that would have moved from moving. </TD></TR></TABLE>
I tend to agree that most of the various reinforcement bars probably don't do much if anything (significant), but some / many chassis respond very well to well designed tower braces...
I tend to agree that most of the various reinforcement bars probably don't do much if anything (significant), but some / many chassis respond very well to well designed tower braces...
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From: strathcedar, nsw, australia
Re: Chassis bracing questions; sharing loads and increasing understeer? (ginsu2k)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ginsu2k »</TD></TR><TR><TD CLASS="quote"> Speaking of front shock tower braces, I went from the very good Comptech Aluminum brace to the Neuspeed tubular steel brace (don't think it's manufactured anymore), and noticed a huge difference. </TD></TR></TABLE>
If you noticed a "huge difference" between the two tower braces then one of them wasn't a good brace...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ginsu2k »</TD></TR><TR><TD CLASS="quote"> If there is any way that you can get a brace that has no pivots (or at least uses two bolts for a pivot) then you are going to get the best bang for the buck. </TD></TR></TABLE>
Tower braces do not increase vertical chassis stiffness at the towers, only lateral stiffness. All forces acting on the tower brace are resisted in compression and tension through the brace bar, which hasn't got the beam strength that would be required to significantly resist vertical deflection at the towers (the chassis is quite stiff in this direction at this pioint anyway).
Whether or not a tower brace is a welded up one peice or bolted together three piece unit makes no in principle difference to the rigidity of the brace. The bolts (if they exist) don't act as 'hinges' because the forces resisted by the brace don't act vertically within the bar but laterally in compresssion / tension through the bar. If the brackets attaching the brace bar to the tower tops are rigidly designed and securely attached to the tower top then no 'hinging' action can occur.
I have seen at least one exception to this, but it was because the brackets were attached to the towers in a less than secure manner, meaning that the brace had to rely upon having two bolts at each end of the bar (attaching the bar to the brackets) to prevent 'hinging' (not a great design).
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ginsu2k »</TD></TR><TR><TD CLASS="quote">Also, adding braces is probably one of the best mods out there simply because they are cheap (some are easily DIY), and because they have such a large effect on chassis stiffness. </TD></TR></TABLE>
Good tower braces are one of the best mods because they work, poor tower braces are a waste of money because they don't work. A lot (most?) of the other various chassis braces available are also a waste of money, well made or not...
If you noticed a "huge difference" between the two tower braces then one of them wasn't a good brace...
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ginsu2k »</TD></TR><TR><TD CLASS="quote"> If there is any way that you can get a brace that has no pivots (or at least uses two bolts for a pivot) then you are going to get the best bang for the buck. </TD></TR></TABLE>
Tower braces do not increase vertical chassis stiffness at the towers, only lateral stiffness. All forces acting on the tower brace are resisted in compression and tension through the brace bar, which hasn't got the beam strength that would be required to significantly resist vertical deflection at the towers (the chassis is quite stiff in this direction at this pioint anyway).
Whether or not a tower brace is a welded up one peice or bolted together three piece unit makes no in principle difference to the rigidity of the brace. The bolts (if they exist) don't act as 'hinges' because the forces resisted by the brace don't act vertically within the bar but laterally in compresssion / tension through the bar. If the brackets attaching the brace bar to the tower tops are rigidly designed and securely attached to the tower top then no 'hinging' action can occur.
I have seen at least one exception to this, but it was because the brackets were attached to the towers in a less than secure manner, meaning that the brace had to rely upon having two bolts at each end of the bar (attaching the bar to the brackets) to prevent 'hinging' (not a great design).
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ginsu2k »</TD></TR><TR><TD CLASS="quote">Also, adding braces is probably one of the best mods out there simply because they are cheap (some are easily DIY), and because they have such a large effect on chassis stiffness. </TD></TR></TABLE>
Good tower braces are one of the best mods because they work, poor tower braces are a waste of money because they don't work. A lot (most?) of the other various chassis braces available are also a waste of money, well made or not...
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