DC4... 19mm ST rear bar... do I need a subframe brace?
03-26-2018, 05:16 PM
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DC4... 19mm ST rear bar... do I need a subframe brace?
2000 Integra GS 2dr, 8k springs front and rear on Skunk2 Pro-C monotube coilovers. 15x7 +35 9.8lb wheels with 205/50 Kumho V720s (200tw)
Car will be street driven and autcrossed 6-8 times per year.
I picked up a brand new Suspension Techniques (KW) sway bar kit 25mm(f)/19mm(r) cheap from a guy that lost interest and sold his car
Now the stock bar is 24mm(f) and 14mm(r), I’m wondering if I need a rear subframe brace to use the 19mm rear bar safely with the 8k/8k spring set up? I plan to install just the rear and if it’s oversteer biased with the even spring rates and 19mm rear bar, I’ll then add the 25mm front bar to neutral balance the car.
i know it’s needed for the big 22-23mm ITR bars and larger 24mm bars in other kits, but the 17mm and 19mm bars from Eibach and ST don’t really comment on the need for a subframe brace.
Thanks!
Car will be street driven and autcrossed 6-8 times per year.
I picked up a brand new Suspension Techniques (KW) sway bar kit 25mm(f)/19mm(r) cheap from a guy that lost interest and sold his car
Now the stock bar is 24mm(f) and 14mm(r), I’m wondering if I need a rear subframe brace to use the 19mm rear bar safely with the 8k/8k spring set up? I plan to install just the rear and if it’s oversteer biased with the even spring rates and 19mm rear bar, I’ll then add the 25mm front bar to neutral balance the car.
i know it’s needed for the big 22-23mm ITR bars and larger 24mm bars in other kits, but the 17mm and 19mm bars from Eibach and ST don’t really comment on the need for a subframe brace.
Thanks!
03-27-2018, 04:23 AM
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Thanks, are you saying it will likely tear out the subframe? Is this based on experience?
Id like an opinion from a seasoned veteran, and maybe someone that has successfully used a 19mm bar without bracing for some period of time.
It is somewhat of a budget build, things that will have little-to-no effect on the real performance or safety of the car should be avoided to save funds for things that will have an effect. If its an absolute must, Ill buy one. Maybe even just sell these again and get the Progress rear bar/brace set up.
Id like an opinion from a seasoned veteran, and maybe someone that has successfully used a 19mm bar without bracing for some period of time.
It is somewhat of a budget build, things that will have little-to-no effect on the real performance or safety of the car should be avoided to save funds for things that will have an effect. If its an absolute must, Ill buy one. Maybe even just sell these again and get the Progress rear bar/brace set up.
Last edited by Pdahondas88; 03-27-2018 at 06:25 AM.
03-27-2018, 09:53 PM
#4
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Re: DC4... 19mm ST rear bar... do I need a subframe brace?
Not an absolute must. But when your looking to refine your package later on it's a worth while add on.
03-28-2018, 05:54 PM
#6
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Re: DC4... 19mm ST rear bar... do I need a subframe brace?
no direct experience but from the research i did..if you're driving the car aggressively (tracking/autoX/bombing on-ramps) and you dont have it..it will tear it apart eventually.
i dont see a reason not to get one unless you plan on just thrashing on the car and selling it to someone else so they have to deal with it.
a $150 brace sounds alot cheaperthan having the thing get ripped apart and having to have it welded/repaired/whatever
just my 2 cents. as someone who is a born penny pincher ive learned over the course of my motorsports career (motorcycles and now cars) is that being cheap is worth it if the downside isnt going to cost more than the part/service.
i used to use cheap clutch levers on my motocross bikes and if you drilled a hole in them or cut them short they'd survive if you fell over sometimes but if you took a big digger the perch would break and it would ruin your whole day at the track unless you had a spare. i upgraded to fancy folding levers (clutch and front brake) and never had to worry about it. they paid for themselves in time...
i dont see a reason not to get one unless you plan on just thrashing on the car and selling it to someone else so they have to deal with it.
a $150 brace sounds alot cheaperthan having the thing get ripped apart and having to have it welded/repaired/whatever
just my 2 cents. as someone who is a born penny pincher ive learned over the course of my motorsports career (motorcycles and now cars) is that being cheap is worth it if the downside isnt going to cost more than the part/service.
i used to use cheap clutch levers on my motocross bikes and if you drilled a hole in them or cut them short they'd survive if you fell over sometimes but if you took a big digger the perch would break and it would ruin your whole day at the track unless you had a spare. i upgraded to fancy folding levers (clutch and front brake) and never had to worry about it. they paid for themselves in time...
03-28-2018, 09:33 PM
#7
Re: DC4... 19mm ST rear bar... do I need a subframe brace?
Thanks, are you saying it will likely tear out the subframe? Is this based on experience?
Id like an opinion from a seasoned veteran, and maybe someone that has successfully used a 19mm bar without bracing for some period of time.
It is somewhat of a budget build, things that will have little-to-no effect on the real performance or safety of the car should be avoided to save funds for things that will have an effect. If its an absolute must, Ill buy one. Maybe even just sell these again and get the Progress rear bar/brace set up.
Id like an opinion from a seasoned veteran, and maybe someone that has successfully used a 19mm bar without bracing for some period of time.
It is somewhat of a budget build, things that will have little-to-no effect on the real performance or safety of the car should be avoided to save funds for things that will have an effect. If its an absolute must, Ill buy one. Maybe even just sell these again and get the Progress rear bar/brace set up.
You can reduce this effect somewhat by making sure that the sway bar moves as freely as possible in its bushings. It won't solve the problem entirely but you will reduce the amount of forces that are trying to yank the sway bar from the subframe by encouraging the sway bar to rotate and twist like it's designed to. If you have polyurethane bushings between the sway bar and mounting brackets, I recommend wrapping the bar in Teflon tape where it contacts the bushing then applying the Teflon / silicon grease on top of the tape. If you're using the stock rubber bushings, make sure they are relatively new. Rubber bushings get harder over time, and that's bad news for a joint that has to rotate.
If your class rules allow for it, install the subframe brace. Cornering loads are very high in Auto-X so you're more likely to experience this problem than us track day guys. It will also help you get a better feel for the rear end which will probably help with this too.
Last edited by boxedfox; 03-28-2018 at 09:33 PM. Reason: Typoed sjg88's username. Oops.
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03-30-2018, 04:08 PM
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Re: DC4... 19mm ST rear bar... do I need a subframe brace?
Can’t run R compound in STX. I’ve got the V720s
I’ll add the brace eventually I think. This 19mm bar comes with reinforcement brackets much like the BSQ/Beaks style, do you think that’s sufficient? Or add bar anyway?
I’ll add the brace eventually I think. This 19mm bar comes with reinforcement brackets much like the BSQ/Beaks style, do you think that’s sufficient? Or add bar anyway?
04-01-2018, 07:26 AM
#14
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04-01-2018, 10:34 PM
#15
Re: DC4... 19mm ST rear bar... do I need a subframe brace?
Doesn't matter the tire, if have a bar, and are tracking I'd put in the brace.
Some may not have ever had any problems but any one I've ever tracked have braces installed. Better to be safe than sorry.
04-02-2018, 05:47 AM
#16
Re: DC4... 19mm ST rear bar... do I need a subframe brace?
You're should be fine to start. Lots of folks did stock rear bars on r-comps in Stock class AutoX before the rules changed a couple of years ago and I don't recall hearing about torn subframes littering parking lots.
I wouldn't worry about it if you're going to a rear bar in the near-future and just going with stock for some events to get a feel for things. I wouldn't go stock bar/no bracing forever though on r-comps.
I wouldn't worry about it if you're going to a rear bar in the near-future and just going with stock for some events to get a feel for things. I wouldn't go stock bar/no bracing forever though on r-comps.
04-02-2018, 07:25 AM
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Re: DC4... 19mm ST rear bar... do I need a subframe brace?
I’m running 200tw tires... idk where he R comp thing came from but I didn’t mention it.
*******NO R-COMPOUNDS WILL BE USED******
Also the bar I have comes with flat plates that bolt to the sub frame to reinforce the mounts. And it’s only a 19mm bar, and I’m running a fairly stiff spring rate, and at the limit of my V720 200 treadwear street tires (NOT R COMPS) the car has very little flex and I don’t see it being a huge issue.
Im not slamming a 24mm bar in the stock holes with no reinforcement, stock suspension, and r compounds... I feel like I laid all that out in the first post but it was just not read.
NO R COMPOUNDS... 8k REAR SPRINGS ON MONOTUBE SHOCKS, NOT THAT LOW, 200 TREADWEAR STREET TIRE/AUTOCROSS TIRES, 19MM BAR, WITH REINFORCMENT PLATES.
Do you still think I’m going to tear out the subframe?
*******NO R-COMPOUNDS WILL BE USED******
Also the bar I have comes with flat plates that bolt to the sub frame to reinforce the mounts. And it’s only a 19mm bar, and I’m running a fairly stiff spring rate, and at the limit of my V720 200 treadwear street tires (NOT R COMPS) the car has very little flex and I don’t see it being a huge issue.
Im not slamming a 24mm bar in the stock holes with no reinforcement, stock suspension, and r compounds... I feel like I laid all that out in the first post but it was just not read.
NO R COMPOUNDS... 8k REAR SPRINGS ON MONOTUBE SHOCKS, NOT THAT LOW, 200 TREADWEAR STREET TIRE/AUTOCROSS TIRES, 19MM BAR, WITH REINFORCMENT PLATES.
Do you still think I’m going to tear out the subframe?
04-02-2018, 09:11 AM
#18
Re: DC4... 19mm ST rear bar... do I need a subframe brace?
I’m running 200tw tires... idk where he R comp thing came from but I didn’t mention it.
*******NO R-COMPOUNDS WILL BE USED******
Also the bar I have comes with flat plates that bolt to the sub frame to reinforce the mounts. And it’s only a 19mm bar, and I’m running a fairly stiff spring rate, and at the limit of my V720 200 treadwear street tires (NOT R COMPS) the car has very little flex and I don’t see it being a huge issue.
Im not slamming a 24mm bar in the stock holes with no reinforcement, stock suspension, and r compounds... I feel like I laid all that out in the first post but it was just not read.
NO R COMPOUNDS... 8k REAR SPRINGS ON MONOTUBE SHOCKS, NOT THAT LOW, 200 TREADWEAR STREET TIRE/AUTOCROSS TIRES, 19MM BAR, WITH REINFORCMENT PLATES.
Do you still think I’m going to tear out the subframe?
*******NO R-COMPOUNDS WILL BE USED******
Also the bar I have comes with flat plates that bolt to the sub frame to reinforce the mounts. And it’s only a 19mm bar, and I’m running a fairly stiff spring rate, and at the limit of my V720 200 treadwear street tires (NOT R COMPS) the car has very little flex and I don’t see it being a huge issue.
Im not slamming a 24mm bar in the stock holes with no reinforcement, stock suspension, and r compounds... I feel like I laid all that out in the first post but it was just not read.
NO R COMPOUNDS... 8k REAR SPRINGS ON MONOTUBE SHOCKS, NOT THAT LOW, 200 TREADWEAR STREET TIRE/AUTOCROSS TIRES, 19MM BAR, WITH REINFORCMENT PLATES.
Do you still think I’m going to tear out the subframe?
04-04-2018, 07:39 AM
#19
Re: DC4... 19mm ST rear bar... do I need a subframe brace?
I’m running 200tw tires... idk where he R comp thing came from but I didn’t mention it.
*******NO R-COMPOUNDS WILL BE USED******
Also the bar I have comes with flat plates that bolt to the sub frame to reinforce the mounts. And it’s only a 19mm bar, and I’m running a fairly stiff spring rate, and at the limit of my V720 200 treadwear street tires (NOT R COMPS) the car has very little flex and I don’t see it being a huge issue.
Im not slamming a 24mm bar in the stock holes with no reinforcement, stock suspension, and r compounds... I feel like I laid all that out in the first post but it was just not read.
NO R COMPOUNDS... 8k REAR SPRINGS ON MONOTUBE SHOCKS, NOT THAT LOW, 200 TREADWEAR STREET TIRE/AUTOCROSS TIRES, 19MM BAR, WITH REINFORCMENT PLATES.
Do you still think I’m going to tear out the subframe?
*******NO R-COMPOUNDS WILL BE USED******
Also the bar I have comes with flat plates that bolt to the sub frame to reinforce the mounts. And it’s only a 19mm bar, and I’m running a fairly stiff spring rate, and at the limit of my V720 200 treadwear street tires (NOT R COMPS) the car has very little flex and I don’t see it being a huge issue.
Im not slamming a 24mm bar in the stock holes with no reinforcement, stock suspension, and r compounds... I feel like I laid all that out in the first post but it was just not read.
NO R COMPOUNDS... 8k REAR SPRINGS ON MONOTUBE SHOCKS, NOT THAT LOW, 200 TREADWEAR STREET TIRE/AUTOCROSS TIRES, 19MM BAR, WITH REINFORCMENT PLATES.
Do you still think I’m going to tear out the subframe?
Most ITT with experience tracking these cars run the brace if rules permit. What you do with that knowledge is up to you.
04-04-2018, 05:02 PM
#20
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Re: DC4... 19mm ST rear bar... do I need a subframe brace?
I’ve actually sold off the ST kit and will soon order the Progress rear bar/brace/link set.
My mind was not made up, that’s why I made this.
I was frustrated in that reply because people kept talking about R-compound tires and such, I felt as though my original post had not been properly comprehended.
But after careful research it seems even the subframe reinforcement kits rip out under hard enough abuse, which is what I had with the 19mm bar. Damaging the chassis of the car isn’t worth saving $100. I just didn’t want to waste money on something that might be overkill if im not running a 22-24mm bar.
My mind was not made up, that’s why I made this.
I was frustrated in that reply because people kept talking about R-compound tires and such, I felt as though my original post had not been properly comprehended.
But after careful research it seems even the subframe reinforcement kits rip out under hard enough abuse, which is what I had with the 19mm bar. Damaging the chassis of the car isn’t worth saving $100. I just didn’t want to waste money on something that might be overkill if im not running a 22-24mm bar.
04-07-2018, 04:53 AM
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Re: DC4... 19mm ST rear bar... do I need a subframe brace?
Since we're on the subframe discussion and autox to an extent...Has anyone read the '18 rules? Are subframe braces even legal in the street touring classes? From what I'm reading you can have front to back in a 2-point mounting brace, but no brace, or SFC if you will going from DS->PS.
Any insight from those experiecened with the rule book wordings/rulings?
Thanks -Dwight
Any insight from those experiecened with the rule book wordings/rulings?
Thanks -Dwight
04-07-2018, 06:05 AM
#22
Re: DC4... 19mm ST rear bar... do I need a subframe brace?
Since we're on the subframe discussion and autox to an extent...Has anyone read the '18 rules? Are subframe braces even legal in the street touring classes? From what I'm reading you can have front to back in a 2-point mounting brace, but no brace, or SFC if you will going from DS->PS.
Any insight from those experiecened with the rule book wordings/rulings?
Thanks -Dwight
Any insight from those experiecened with the rule book wordings/rulings?
Thanks -Dwight
Section 12 of the Solo rulebook defines a strut bar as:
- A transverse member connecting the upper or lower suspension mounting points at the front or rear of the car. Strut bars may be mounted only transversely across the car from upper left to upper right suspension mounting point and from lower left to lower right suspension mounting point. A two-point strut bar fastens only at the left and right suspension pointing points. A triangulated strut bar has a third area of attachment at the chassis (e.g., at the firewall/bulkhead). All connections to the vehicle must be bolted. No connection point to the chassis can be welded.
The Street Touring Section permits strut bars with the following provisions:
G. Strut bars per Section 12 are permitted with all types of suspension, subject to the following constraints:
G. Strut bars per Section 12 are permitted with all types of suspension, subject to the following constraints:
- A 2-point strut bar may be added, removed, modified, or substituted, but only with another 2-point strut bar.
- A triangulated (3-point) strut bar may be removed, modified, or substituted; substitution may be with either a triangulated or a 2-point strut bar. The connection to the chassis (e.g., firewall, bulkhead) must be in the standard location.
- Lower suspension braces must be attached to the lower suspension pickup point locations on the chassis within 2” (50.8mm) in any direction of the actual suspension attachment to the chassis.
- Except for standard parts, no connections to other components are permitted.Additional holes may be drilled for mounting bolts. Only “bolt-on” attachment is permitted. Interior trim panels may be modified to allow installation of strut bars. Holes or slots may be no larger than necessary and may serve no other purpose. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.
Basically I'd assert that the subframe brace is a strut bar that ties together the lower suspension pickup points using holes that are within 2" of the lower control arm mounting bolts on either end. You don't need to weld the bar on and you don't need to modify the subframe to attach the brace.
In practicality I don't think anyone's going to argue with you or make you take it off. It's not enough of a performance difference to make an advantage, even if the car feels more solid with it on.
Last edited by boxedfox; 04-07-2018 at 08:03 AM.
04-07-2018, 09:46 AM
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Re: DC4... 19mm ST rear bar... do I need a subframe brace?
I just looked at the 2018 March SCCA Solo rules, and based on their definition of strut bar, the Street Touring allowances for strut bars, and the subframe braces I've seen, I would say the answer is yes.
Section 12 of the Solo rulebook defines a strut bar as:
- A transverse member connecting the upper or lower suspension mounting points at the front or rear of the car. Strut bars may be mounted only transversely across the car from upper left to upper right suspension mounting point and from lower left to lower right suspension mounting point. A two-point strut bar fastens only at the left and right suspension pointing points. A triangulated strut bar has a third area of attachment at the chassis (e.g., at the firewall/bulkhead). All connections to the vehicle must be bolted. No connection point to the chassis can be welded.
The Street Touring Section permits strut bars with the following provisions:
G. Strut bars per Section 12 are permitted with all types of suspension, subject to the following constraints:
G. Strut bars per Section 12 are permitted with all types of suspension, subject to the following constraints:
- A 2-point strut bar may be added, removed, modified, or substituted, but only with another 2-point strut bar.
- A triangulated (3-point) strut bar may be removed, modified, or substituted; substitution may be with either a triangulated or a 2-point strut bar. The connection to the chassis (e.g., firewall, bulkhead) must be in the standard location.
- Lower suspension braces must be attached to the lower suspension pickup point locations on the chassis within 2” (50.8mm) in any direction of the actual suspension attachment to the chassis.
- Except for standard parts, no connections to other components are permitted.Additional holes may be drilled for mounting bolts. Only “bolt-on” attachment is permitted. Interior trim panels may be modified to allow installation of strut bars. Holes or slots may be no larger than necessary and may serve no other purpose. This does not permit any modifications to the frame or unibody beyond the allowed mounting holes.
Basically I'd assert that the subframe brace is a strut bar that ties together the lower suspension pickup points using holes that are within 2" of the lower control arm mounting bolts on either end. You don't need to weld the bar on and you don't need to modify the subframe to attach the brace.
In practicality I don't think anyone's going to argue with you or make you take it off. It's not enough of a performance difference to make an advantage, even if the car feels more solid with it on.
Thanks man!
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