Hm, everything seems to jive with your setup, its very similar to mine. Only difference that I can see affecting the steering feel is that you have much less camber therefore a larger contact patch and more frictional resistance. Also, are you positive your toe is straight? Toe in, especially with wide tires can contribute to increased steering effort.
RSX Suspension Modeling Results
I recently took a vehicle dynamics class. We needed to do a class project, so I (and two additional group members) chose to model the RSX suspension. I am attaching the final report so that everyone here can benefit from it. Note, I am posting this here in the autocross forum rather than the suspension forum because it is more relevant to those of us who track our cars or do autocross.
Basically, the car's suspension was measured so that the location of every suspension point was known in x, y, and z coordinates. Next, the suspension was modeled in Solidworks. From this point, lots of info can be measured/calculated.
Anywho, we looked at camber gain, both from suspension compression and from steering input. We also did roll center heights and bump steer. All of these were done for the front and rear. Additionally, aftermarket modifications were 'made' to the model and their effects on the above parameters analyzed. The modifications made were roll center adjusting ball joints, caster/camber plates that move the strut top inward 3/4" and rearward 3/4", raising the inner tie rod ends 1.25", and lowering the inboard side of the rear top link of the rear suspension 3/4".
DISCLAIMER: Every attempt was made to be as accurate as possible during this project. However, it is exceedingly difficult to measure the suspension perfectly. As such, I do not guarantee any values as being 100% exact. They should be pretty darn good though.
Basically, the car's suspension was measured so that the location of every suspension point was known in x, y, and z coordinates. Next, the suspension was modeled in Solidworks. From this point, lots of info can be measured/calculated.
Anywho, we looked at camber gain, both from suspension compression and from steering input. We also did roll center heights and bump steer. All of these were done for the front and rear. Additionally, aftermarket modifications were 'made' to the model and their effects on the above parameters analyzed. The modifications made were roll center adjusting ball joints, caster/camber plates that move the strut top inward 3/4" and rearward 3/4", raising the inner tie rod ends 1.25", and lowering the inboard side of the rear top link of the rear suspension 3/4".
DISCLAIMER: Every attempt was made to be as accurate as possible during this project. However, it is exceedingly difficult to measure the suspension perfectly. As such, I do not guarantee any values as being 100% exact. They should be pretty darn good though.
Attachments
-
620.8 KB Views: 3,300
-
32 KB Views: 1,148
81 - 100 of 107 Posts
So from what I've been reading, I guess its a good thing that I didn't get the bracket or inverted ends.
Wow...a lot of amazing information here. How is this not stickied?
:bowdown::bowdown::bowdown::bowdown::bowdown:
:bowdown::bowdown::bowdown::bowdown::bowdown:
Agreed. I need to take some more time looking at this. I've been experiencing a major bump steer issue and I'm trying to legitimately take the time to alleviate it, versus reading what most folks assume to be helpful.
i was thinking of relocating the whole steering rack to the bottom front of the engine bay and installing a Mustang rack/pinion , relocate the steering arms and knuckles to the front of the wheel hub. rack level with the front LCA's, shorter tie rods. now how do i do this???
^ That sounds like a lot of custom work...you might as well try to install a TSX double-wishbone in the front
Been peeping your Circuit DC5 build thread from time to time. Can't wait til you model the suspension specifically with the Buddy Clubs-- I still have mine but I've tested some other arms from other manufacturers to toy with the angles and what not. Sadly, I didn't measure the Buddy Clubs before I took them off. (RSDs)Hm, everything seems to jive with your setup, its very similar to mine. Only difference that I can see affecting the steering feel is that you have much less camber therefore a larger contact patch and more frictional resistance. Also, are you positive your toe is straight? Toe in, especially with wide tires can contribute to increased steering effort.
Keep us updated. I wouldn't have expected that with your coil-overs but it seems with this car, the height affects it too greatly. EasyE's EP3 is pretty low tho and my DC5 is at 4.5" front pinch and 4.75" rear pinch. Tie rod arms are close to perpendicular (forget the exact degree it is off) but jumping into a double wish car made the bumpsteer in the DC5 much more noticeable despite years and years of daily driving and track use w/o complaint.Agreed. I need to take some more time looking at this. I've been experiencing a major bump steer issue and I'm trying to legitimately take the time to alleviate it, versus reading what most folks assume to be helpful.
Too much work and is probably why it hasn't been done.i was thinking of relocating the whole steering rack to the bottom front of the engine bay and installing a Mustang rack/pinion , relocate the steering arms and knuckles to the front of the wheel hub. rack level with the front LCA's, shorter tie rods. now how do i do this???
Yeah, I didn't notice how bad it was until I went to Buttonwillow and wrestled the steering wheel for 2 straight days.
I have bump steer issues too... This is an interesting idea... but sounds like A LOT of work. Something to think about though.i was thinking of relocating the whole steering rack to the bottom front of the engine bay and installing a Mustang rack/pinion , relocate the steering arms and knuckles to the front of the wheel hub. rack level with the front LCA's, shorter tie rods. now how do i do this???
Does anyone know where I can get those spacers for the rear camber arm from the PDF file on the original post or can I just use washers?
It's funny...I didn't really notice it too much until 1.) I got to Buttonwillow and felt like I was wrestling a juiced up grizzly bear and 2.) my teammate who has won H1 and run in Speed World Challenge was completely blown away with how he had to fight the car. It's weird, it's not torque steer really, but the car just pulls and fights with every surface discrepancy.Keep us updated. I wouldn't have expected that with your coil-overs but it seems with this car, the height affects it too greatly. EasyE's EP3 is pretty low tho and my DC5 is at 4.5" front pinch and 4.75" rear pinch. Tie rod arms are close to perpendicular (forget the exact degree it is off) but jumping into a double wish car made the bumpsteer in the DC5 much more noticeable despite years and years of daily driving and track use w/o complaint.
The car is great under trail braking (as long as the braking zone isn't bumpy), and sometimes understeers mid-corner, but is fairly neutral for an FF car...but throttle on corner exit is rough. As much as I'd like to try to get on the throttle early, it's difficult with the understeer on corner exit, so instead I brake incredibly late, upset the car and try to minimize any coasting, thus rotating immediately before understeering.
I'm going to see what I can do to mitigate it, but from what it seems like, it's a bit of a problem that even the top teams had to compromise with to some extent.
While my teammate disagrees that it could be much of a possibility, I do sort of feel like it got worse once I didn't have to adhere to the Redline ride height rule. That said, I watched a bunch of my old videos and I always had a bit of bump steer. Hopefully I can resolve it before Super Lap. The car is pretty dialed in otherwise.
I think the revelation was a result of a decent amount of seat time at a new track that's really smooth (Thunderhill) and then going to a brand new track (Buttonwillow) that I wasn't used to. The bumps, especially in the higher speed stuff, were pretty unsettling when my first time out I was attempting to run close to 2-min.
After the weekend my arms were actually tired...something I've never experienced save for my first karting enduro. Kinda weird.
I'm trying to see if I can get some data from Realtime to see what they did with their RSX (rear suspension nonwithstanding), but so far no luck.
I'm not running any inverted tie rods, but I am running the J's steering arms (tie rods), RCAs and the Racing Gear/J's suspension has the flat, level bracket for the steering arms. I wonder if I need bigger RCA/ball joints to compensate for the lower roll center? Toe is neutral in front, maxxed out in the rear. I just don't know how to measure what the difference would be.
I'd ask EasyE-- saw some nice ones he made w/ new hardware (12.9 grade I assume) but I'm not sure if he's producing them for distribution-- sorry. Was going to ask him as I'm tearing into mine again, but haven't.Does anyone know where I can get those spacers for the rear camber arm from the PDF file on the original post or can I just use washers?
Funny-- I was at work today looking at RTR pics, and couldn't find any other than what's been posted here (rear sussy) I think. I know I saved many RTR pics on Pbucket before-- I'll try to post some, but I guarantee you it's a lot of changes, particularly in the rear (think sway bar visible in the cabin for starters).It's funny...I didn't really notice it too much until 1.) I got to Buttonwillow and felt like I was wrestling a juiced up grizzly bear and 2.) my teammate who has won H1 and run in Speed World Challenge was completely blown away with how he had to fight the car. It's weird, it's not torque steer really, but the car just pulls and fights with every surface discrepancy.
The car is great under trail braking (as long as the braking zone isn't bumpy), and sometimes understeers mid-corner, but is fairly neutral for an FF car...but throttle on corner exit is rough. As much as I'd like to try to get on the throttle early, it's difficult with the understeer on corner exit, so instead I brake incredibly late, upset the car and try to minimize any coasting, thus rotating immediately before understeering.
I'm going to see what I can do to mitigate it, but from what it seems like, it's a bit of a problem that even the top teams had to compromise with to some extent.
While my teammate disagrees that it could be much of a possibility, I do sort of feel like it got worse once I didn't have to adhere to the Redline ride height rule. That said, I watched a bunch of my old videos and I always had a bit of bump steer. Hopefully I can resolve it before Super Lap. The car is pretty dialed in otherwise.
I think the revelation was a result of a decent amount of seat time at a new track that's really smooth (Thunderhill) and then going to a brand new track (Buttonwillow) that I wasn't used to. The bumps, especially in the higher speed stuff, were pretty unsettling when my first time out I was attempting to run close to 2-min.
After the weekend my arms were actually tired...something I've never experienced save for my first karting enduro. Kinda weird.
I'm trying to see if I can get some data from Realtime to see what they did with their RSX (rear suspension nonwithstanding), but so far no luck.
I'm not running any inverted tie rods, but I am running the J's steering arms (tie rods), RCAs and the Racing Gear/J's suspension has the flat, level bracket for the steering arms. I wonder if I need bigger RCA/ball joints to compensate for the lower roll center? Toe is neutral in front, maxxed out in the rear. I just don't know how to measure what the difference would be.
I didn't get to BW with the RSX, only Willow Springs and Streets, but driving in a double wish with travel at BW 13CW was nice, even though I expected some rough turns-- the slight L after Riverside (only done 13CW twice) which kicked the rear end of a Miata flipping it several times, was no big deal in mine. Can't imagine in an RSX.
To the OP: not sure if he's still here, but reading the report again after how many years got me curious about how the camber plate changes were determined. It's possible to run a plate w/o changing kingpin/SAI (dead center) and it is not noted where the top pivot was changed in the camber plate config.
Like the OP I've ran Buddy Clubs for years and have ran the plates swapped from the beginning. Was able to get +4.5 caster which at the time was a lot supposedly for this chassis (moved subframe forward as well). Only after adding RCAs within the past couple years have I noticed how awkward the rear is compared to the front (no tie rod inversions/relocations here).
I was thinking of something similar, but trying to use an 06+ Civic Si electric power steering setup, mounted behinds the front axle but down low as on the 8th gen, then use the 8th gen knuckles and front struts. Just brainstorming crazy projects lol but I doubt I will ever attempt it in my car as Ive sorted out the front end pretty well now and am happy with how it behaves. Who knows maybe some day way down the road!i was thinking of relocating the whole steering rack to the bottom front of the engine bay and installing a Mustang rack/pinion , relocate the steering arms and knuckles to the front of the wheel hub. rack level with the front LCA's, shorter tie rods. now how do i do this???
What lower ball joints are you using? also what is your KPI? Sounds like when the front unloads under corner exit your arms are flattening out a bit, pushing out the back side of the wheel causing toe in, which would definitely cause your symptoms. An easy way of trying to reduce the affect is to prevent weight transfer to the rear which can only help in these cars. You can do that with either stiffer spring rates and or more compression damping in the rear which will slow the transfer of weight.It's funny...I didn't really notice it too much until 1.) I got to Buttonwillow and felt like I was wrestling a juiced up grizzly bear and 2.) my teammate who has won H1 and run in Speed World Challenge was completely blown away with how he had to fight the car. It's weird, it's not torque steer really, but the car just pulls and fights with every surface discrepancy.
The car is great under trail braking (as long as the braking zone isn't bumpy), and sometimes understeers mid-corner, but is fairly neutral for an FF car...but throttle on corner exit is rough. As much as I'd like to try to get on the throttle early, it's difficult with the understeer on corner exit, so instead I brake incredibly late, upset the car and try to minimize any coasting, thus rotating immediately before understeering.
I'm going to see what I can do to mitigate it, but from what it seems like, it's a bit of a problem that even the top teams had to compromise with to some extent.
While my teammate disagrees that it could be much of a possibility, I do sort of feel like it got worse once I didn't have to adhere to the Redline ride height rule. That said, I watched a bunch of my old videos and I always had a bit of bump steer. Hopefully I can resolve it before Super Lap. The car is pretty dialed in otherwise.
I think the revelation was a result of a decent amount of seat time at a new track that's really smooth (Thunderhill) and then going to a brand new track (Buttonwillow) that I wasn't used to. The bumps, especially in the higher speed stuff, were pretty unsettling when my first time out I was attempting to run close to 2-min.
After the weekend my arms were actually tired...something I've never experienced save for my first karting enduro. Kinda weird.
I'm trying to see if I can get some data from Realtime to see what they did with their RSX (rear suspension nonwithstanding), but so far no luck.
I'm not running any inverted tie rods, but I am running the J's steering arms (tie rods), RCAs and the Racing Gear/J's suspension has the flat, level bracket for the steering arms. I wonder if I need bigger RCA/ball joints to compensate for the lower roll center? Toe is neutral in front, maxxed out in the rear. I just don't know how to measure what the difference would be.
I didnt have these issues in my EP even with the crappy EPS. The car was a dream to drive around the track (granted it was fairly smooth). Daily and highway driving with that EPS was a nightmare though, so Im excited to see how the car does on the track now with my 06 DC5 power steering retrofit.
Does anyone know if maybe swapping the EPS from a EP3 type-R would correct some of the EP's stock EPS misgivings?
strikeflo: yes, the on power corner exits are a 2/10ths killer. did sfr autox from 05 to 10 and can say from numerous times out there that yes, brake late, rotate, point nose, then get on gas. seemed like forever. i'm open diff. i drove a 1.5 diff rsx on the same day autox as my own. slaloms felt better , tighter. and exit sweepers with smooth throttle roll on were nice.
trail brake at Thill? wow ! i did on turn 3 because of the small crest and off camber downhill , mistake for me, rear came out, not violently but at speed way faster than any autox. i caught it
i think i can say that the rsx suspension geometry is fine stock, but to drive it at the limit, you have to be very smooth. put a cup of water in the cupholder smooth.
all this suspension talk made me take a look at my own set up. and i know that it's weak. hks hypermax 6kgfr 9kgrr. these coils are 4 years old and i need a better set in the future.
front springs are weak in that i get slow rebound, i feel the springs do not have enough force to keep the nose level in certain surface depressions.
high speed compression=great ff and rr. low speed compression, not so good. the feel they want to bottom at 10-15 mph over small bumps.
for a daily driver, it's pretty good.
i hope this is still on topic???
trail brake at Thill? wow ! i did on turn 3 because of the small crest and off camber downhill , mistake for me, rear came out, not violently but at speed way faster than any autox. i caught it
i think i can say that the rsx suspension geometry is fine stock, but to drive it at the limit, you have to be very smooth. put a cup of water in the cupholder smooth.
all this suspension talk made me take a look at my own set up. and i know that it's weak. hks hypermax 6kgfr 9kgrr. these coils are 4 years old and i need a better set in the future.
front springs are weak in that i get slow rebound, i feel the springs do not have enough force to keep the nose level in certain surface depressions.
high speed compression=great ff and rr. low speed compression, not so good. the feel they want to bottom at 10-15 mph over small bumps.
for a daily driver, it's pretty good.
i hope this is still on topic???
Why couldn't I have read this 5 hours ago I just ordered inverted tie rods.
^ Cancel them, quick!
Don't think I can Im sure they are already on there way I overnighted them so I could get my alignment done tomorrow.
it's been years, but this to me makes a DC5 driver more credible as a driver than anything else then.i think i can say that the rsx suspension geometry is fine stock, but to drive it at the limit, you have to be very smooth. put a cup of water in the cupholder smooth.
thank you sir !!!it's been years, but this to me makes a DC5 driver more credible as a driver than anything else then.
81 - 100 of 107 Posts
- This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Acura RSX, ILX and Honda EP3 Forum
A forum community dedicated to Acura RSX, ILX and Honda EP3 owners and enthusiasts. Come join the discussion about performance, modifications, troubleshooting, K24 swaps, turbo kits, and more!
Full Forum Listing
Explore Our Forums
