[black dc5]

seems like you've over stiffened the suspension past what the tires require.

Remember, there is a big difference between tuning the amount of grip a car has and tuning the cars handling balance. and stiffening the suspension past what the tires would require just means less overall grip (higher suspension frequency = lower mechanical grip)

so, i'd ask is the cars problem a balance issue or a grip issue.

^+1

 

[black dc5]

for the most part the same things that make your car handle better will also make the tracking problem worse, such as wide, sticky, low profile, tires, lots of neg. camber and toe out. I have just learned to live with it and realize it is the price you pay.

how wide are ur front tires?

this is the reason i'm selling my 255s tho...
it is insane just daily driving.

 

[black dc5]

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.

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)

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.

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.

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???

Too much work and is probably why it hasn't been done.

 

[black dc5]

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?

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.

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.

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).

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).

 

[black dc5]

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.

it's been years, but this to me makes a DC5 driver more credible as a driver than anything else then.

 

[black dc5]

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???

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???

It might as well be. I'm no shock builder, but I think that high speed/low speed piston disparity is due to the sub-optimal curve our coil-overs may have. Sounds more/too progressive which is typical of these cheaper dampers a few of us run and from my experience, you must make a compromise as it will not have a good/decent setting @ both. I choose to optimize it at low speed piston speeds if the track is faster (for high MPH control), hoping it doesn't get too upset at bumps (high speed). Buttonwillow, for me, for example, and the opposite for a slower course-- Streets of Willow (which many just call an overgrown Auto-X course). On the street, I prioritize the high speed valving range since the roads around here are rather rough. Above all, give the suspension travel to do the best it can.

 

[black dc5]

i just think of piston velocities of the force the damper is capable of