^^^

 

what happened..???

 

nothing, I just want a spare bumper to hack for superlap sessions. The bumper cavity is being a real "drag"

 

ohhh I see... you should try asking V35Coupe... I doubt he will need his rear bumper... well not until it was damaged... hmmm... I haven't seen him up in this forums ever since that topsecret widebody G from Maui made it's debut...

 

chris, you seem to be a real superlap enthusiast. just make cut outs for diffusers already. just like drag racing. is it really noticeable how it drags more with the single than with the OEM muffler??

 

I can feel the back end getting a bit lofty at over 130mph when I was testing the car's power. Under hard braking the back end gets squyirly, swaying side to side till I hit a neutral feeling and and the back end stabilizes. But that was long course and Solo 1 territory. SLS utilizes the short course. On the Short course, it hinders me a little bit through the sweeper that the **** end wants to come loose...it "looks" cool and adds to drama...but I dont need that. I need the back end to stick. The under braking it does the same thing where it sways side to side but not as bad as coming from +130 mph braking for a corner. The stock muffler has an effective spoiler the pulls the back end down, and I could feel why it needed it. The bumper as it is is causing a parachute effect where it captures air...granted that the stock underspoiler did that, it ultimatly didnt cause any slowing down. Thats why I want a spare bumper to hack and cut out holes (the diffusers sen_jen is regarding) to relieve the pressure built up pushing the back end up and outwards the bumper.

 

^ okay, i may be able to get you a stock one that is scratched up. i'll let you know. it may take a while, but i'll keep you informed killer.

 

thanks!!

 

could you put an aluminum sheet under there, kinda like the carbon ones the r34 has. it would help to get the air under there flowing a little better, if you can design one correctly that won't add drag.

 

heh..the last thing I need is to "add drag"...but I get what you mean be reducing drag.

I did contemplate that idea but it's too hard to execute. I'd have to some how mold a template and shape it then try and take it off to make a finish. the cost of materials would probably be the same as just buying a used bumper and hack it. given that it would be a unique oppurtunity and an accomplishment if I could pull it off...but it's just more work than I need to deal with.

 

i might be able to sell u mine, it got rear ended, so getting a new one. doesn't anyone have a good aftermarket bumper i can buy?

 

How were you going to reduce that pocket of dead space between the rear suspension mounts and the rear bumper? There are no anchor points to gerry rig something to it? The lip of the bumper curls down a little to close the gap that was between the edge of the OEM muffler..but nothing more than that. Are you trying to modify the bumper...or the gap in the rear?

My suggestion would be to just remove the piece in the outlined area. Unless you close the gap between the suspension mounts to the rear of the car....just modifying the bumper alone wont really help. BTW, not to disrespect your experiences on the track...but could the float be from the reduced weight in the rear? I think that I lost about 50-70 pounds from the removal of all the extranious pieces back there...like I said...enough that the right rear corner actually lifted up a couple of inches.

When running in SCCA..there is a little bit of a sensation of a slight lift when braking hard going into a turn. Its also a little easier for me to transfer the weight from the rear to the front to induce oversteer and change slip angles on the fly.

On your track outings you exceed 90 MPH while I hit 60-65 MPH...so maybe you experience more "float" and drag than I do. Different track activities create different symptoms and issues, I understand.

Anyhow, my thoughts are just that modifying the bumper alone will still cause air to build up behind the rear suspension mounts as it flows over and hits the backside of the bumper...modified or not...there will still be a slight pocket due to the size of the now apparent dead space back there.

Just my thoughts though.

 

Oh all this talk of racing around lol... Solo II is this sunday! I hope I can make it.

 

Hey Dave, I see what your saying about the weight, it's ugly face shows itself when I'm midway and exiting turn-1 where I'm sliding and getting oversteer, I'd have to be redlining the bizatch out of the engine, powering out of the turn. And the Sweeper? It has all of a sudden gotten a lot scarier because the tires breaks loose more than before and the slide angle is a lot steeper. I found myself backing off and letting the body weight move foward going at part throttle all the way through instead of going WOT after hitting the apex by the guardrail like I usually do. Sooner or later I'll be able to force it in...but for now...I'll be playing safe. The crappy thing is, the runs were on the RT615, and I expect something different when I get the 17x10s and NT01 on. I hope I'll get them in before the 28th. A few other things are going to be installed by then...but it's just a matter of when I get them in on time.

As for the lift, I can't really feel it till I'm over 100-110ish on the straight. More so when I'm closing in on turn-1 long course at over 120mph. I could always take the time to fabricate some kind of plate to cover up the void, I could also risk creating more lift that I need. I just thought that i figured that the natural tendency is for air to fill up the void, creating holes on the will provide a means of relieveing the pressure.

I could always do the D1 look and get one of those low height Signal Auto wings. then I'd need a spare trunk to bolt that on to.

 

LOL. Okay, I am not imagining things when I refer to the rear of the car getting a lot lighter. The weight transfer and pitching has changed a lot and I do find it a little uneasy at times in anticipating when its going to break loose. Just a matter of getting used to the new feel I guess.

I have been testing out the BF Goodrich KDW 2's. Not too bad for a street tire. Even though the treadwear rating is high...the tire grips relatively well. So far I am impressed and happy. I needed a street/strip type of tire anyway...this sort of works. Just need to heat them up a little and then its a lot better.

I think that if you could find a way to channel the air out past that little void area, you will be okay. Creating a outlet in the lower bumper may solve some of the problems...but create another in regards to appearances. Use the area right above the exhaust tips and cut upwards a little more to allow more air to pass through. Might be the easiest way to solve the issue without looking too ghetto. Then get a flat sheet of aluminum and fill that gap in front of the rear bumper to the rear suspension supports. Simple but should be effective in keeping the air from building up there.

Look into the Nismo wing. I heard that it was actually supposed to create downforce and aerodymanics as well. That would also solve the issue in keeping the rear down as well.