I was hoping I can get some help from the community on 3 distinct noises I am experiencing with the 1995 Mitsubishi Eclipse on the Indy Oval turns (#1 & #3) or right after exit of turn #1. The 3 noises include sort of a (1) “thump” noise, a (2) “slap” noise", and, a (3) scraping noise. Here is what I have done so far.
I built the car (D-class) and through in a base tune to test out at the Indy Oval. I started to get some decent times and wanted to now start tweaking my tune. I had heard the noises yet decided to tweak a couple of other items prior to addressing this part. So, now to get rid of the noise(s).
I decided to first focus on the Ride Height. On my initial base tune I had set the ride height to minimum (5.6/5.3 F/R), so, I went to the max (7.8/7.5) just to see if the noises went away…and, yes they did. I then proceeded to change to drop the ride height until I could here the noise(s) again. I changed both from & rear, and, also tested just changing the rear or front ride height. For example at minimum front and 6.4 rear I got no noise.
I did not want to just blame the ride height, so decided to now play around with the Rebound & Bump settings. I initially had these at 12.5/13.0 R and 2.5/2.0 B. I decided to set the ride height at 6.5 for the front & 6.2 for the rear, basically +9 clicks for both to start. So now I just modified these to 11/11 & 4/4, 10/10 & 4/4, 9/9 & 4/4…finally getting to a combination of 9/9 & 3/3 with no noise. I proceeded now to decrease ride height with no success.
I know there is probably a combination where it will/should allow me to reduce the ride height so I can get some additional speed from the car, and, get rid of the noises (which impact performance).
Any suggestions or ideas for me to try out (ride height, rebound/bump combo, other)? Where do you usually start when encountering this issue and/or if you were to run into this? +9 clicks for RH seems excessive, thinking maybe (at the most +4)…thoughts?
Good point! I actually do keep the throttle down, however, at the turns the speed inherently decreases thus these interdependencies come into play and the noise(s) comes up. I’ll try at another track and check turns.
I’m not sure about a D class car (they usually can be pretty high off the ground compared to race car), but I find that max ride height on the front almost always works out the best. More speed even not just the bottom out factor.
I’m not knowledgeable enough to comment on the suspension settings. I would start with springs from your base. I just move in increments and run laps continue.
If you look at the benchmarking on the left after adjusting (especially high HP). You can see it for your self. Higher ride height in the front than rear is pretty normal for oval tunes.
I tested font at max and rear at min, and then reversed these (front min, rear max) and just got a less than two tenths of a second difference. yet, not sure my driving inconsistency can alter this either way. The RH difference between min/max in this car is a total of 2.2". I tend to not fully take the Forza data for “granted” since I have encountered many inconsistencies. I’ll keep testing. Thanks for your inputs.
Here is what Forza provides for speed on this car:
Changing Ride Height (all else the same)
Front Rear Speed
Min Min 167.0
Max Min 166.1
Min Max 167.9
Max Max 167.0
So, it shows max speed when front is Min and rear is Max! When car is set at both Min or Max is 2nd highest speed. When Front is Max and Rear is Min, it’s the lowest (1.8mph less that best shown)!
My experience was in the zonda, toyota LMP, and Indy car. (#22 in S, #34 in R both in my Zonda tune, #189 in P ( need to revisit- but it was a quick throw together tune- To run in an actual LMP car instead of an Indy car with drag tires - I feel the class is for LMP cars so I’m restricting myself - but at one point I was #89), #99 in X ( That Guys Average tune - Takumi’s is fast too - mine tune never made it to the light of day - I had maxed out everyone elses tune in the Zonda at the time so I was forced to do it on my own with some help from SatNite - but it since evolved away from that)
I would still suggest the higher ride height in the front to stop the scraping ( May be not max- there isn’t much adjustment on the cars I did it in). But honestly it’s all what works best for you. Now that I’ve gained a little more experience modifing OS tunes, talking with tuners (mainly PTG), and reading tuners comments here I feel I can do a bit better and not shoot in the dark as much as I was and I plan on revisiting the Zonda to see about getting back into the top 10. My indy car tune attempts were terrible, but I’ll have another go at them.
This is a total guess (my gut says)- adjust your springs - or your bump may be too low or rebound, but me personally I would adjust spring evenly (if balanced) a bit stiffer and see what it does. But it may be that you have too much travel and the bump may solve it — THIS SHOULD ALL BE TAKEN WITH A GRAIN OF SALT… I just trial and error to a result… but either the car is too low (scrape). If you don’t break - which I assume you don’t you shouldn’t be getting to much transfer to the front- rather it the road rising in front of you… At Prague- I thought I would need stiffer springs but it was actually the other way… so I would just move evenly one way or the other and find out if it solves the problem. My springs on my Zonda are pretty stiff but that was back in January and I had absolutely NO idea what I was doing… My metric was is it faster around the track or not… I would make sure to set your braking pressures really low as well, some times a slight tap makes all the difference between hitting a wall or not and with low pressures it works as a trail brake minor correction and you don’t have to do another two laps to get going again.
I follow the advise given to me by Rosney and Mesa and I have no idea half the time… in the math thread over there, and then moving springs around to achieve balance and then moving them 50 at a time softer then move to 25s… to fine tune… Keeping in mind of the ARB stiff for soft springs and then once there i make tweaks on the ARBs to get more or less understeer. I’m a fool when it comes to Rebound and bump- I start with high rebounds 10.5 and low bumps 3.0 and tweak each in .2’s … (from the how to tune base tune to specific track- thread) It would be nice to group all the info in one place. But it seems when you do it becomes too much to understand for a n00b like me. SO I get in a good tune and then modify to the new track and that way I’m starting to pick out what works where and what to change. But I make the wrong assumptions a lot- think stiffer and the answer is softer… kind of thing. So in other words its just a slow process (for me)… But I’m getting the car to the way I like it and I was able to coax another 2 seconds from a Spa tuned car to a Prague tuned car so I say the method works pretty good…
I wish you the best luck and if you want me to try it out I will and give you my feed back. I’ve got to work on my S class Viper for Road America - 30 lap race so I won’t really have the time to try on my own, but If I get some time may be I throw one together and we can compare…
I think I shared my Zonda Oval over at PTG Forum… If you want to take it for a spin ( or I can forward in a PM)… And the S800 Viper '13 is pretty fast as well - Rosney helped on the suspension - and now I modify from track to track. The Zonda is probably going to get reworked now that I get the suspension… but it’s hard to argue with the results… I think I’ll get it balanced and then maybe see if toe helps afterwards instead of the guess method, I used…
Make sure you post your results and findings. I’m definitely interested to find out what ends up working and how you get along with it!
I will certainly keep some extra clicks on the front. My testing so far suggests it needs at least 3-4 clicks.
This is actually a good guess and I yesterday I “reset” myself and revisited the springs…and…still tweaking to see which I have seen a lot of improvement, yet, still getting some noise depending on the line I use on the track…so…it depends on the are of the track and/or bumps in the neighborhood. I am adjusting springs and Rebound/Bump combo. After that, I will start dropping the ride heights and ensure I do not get the scraping from height body interference.
Yeah, the PTG group (Rosny, Mesa and others) are a great resource. I also use their site and as a beginner tuner I have learned much from it. I also start my rebounds in the 9.5-12 zone and bumps in the 1.5 to 4.0 zone and use a similar process to get a “good” landing spot.
Thanks for the offer! I’ll let you know when the car is ready (for now, if you’d like you can check my BRZ tune for the Oval, D-class, posted on another thread)
I’ll certainly check out your Zonda & Viper and take them for a spin.
I will keep posting my results as I continue to learn & tweak/adjust for these issues.