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Old 08-19-2002, 10:18 AM   #331
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I've been working on dialing in my friend's Evo2. I think I've got a really good setup for smooth asphalt. I will update here when I get it all typed out.

Front:
40W, Tamiya yellow, no rebound sponge
center hole for shock, 3mm spacer under inner upper link
gearbox shaved and 1.5mm spacer underneath rear hingepin (less caster)
no swaybar, 6mm droop with TC3 gauge
wheelbase spacers fwd (arms back)

Rear:
30W, Tamiya yellow, no rebound sponge
center hole for shock, 4mm spacer under inner upper link
outside hole on hub carrier
1 dot rear hingepin block (414M)
stock swaybar, 7mm droop with TC3 gauge
wheelbase spacers fwd (arms back)

Tires: CS32R

One of the primary problems I see with the Evo 2 is weight distribution and overall weight. First of all, the thing is a porker. If you get rid of the old TB01 style battery tray and use strapping tape, you can run lighter electronics like a GM, LRP, or KO ESC and still come up 50/50 L/R. It also drops off over an ounce from the weight. After that, do whatever you can: Ti screws, etc to get that thing down to 53 oz. I remove the center post and the 2 central screws in the front top deck to get a little more chassis flex.

The next order of business is F/R weight distribution. The stock settings of the Evo 2 are something ridiculous like 6X/3X. By running the arms full rearward in front and rear the ratio is something like 5X/4X. Not optimal, but still better. One of my friends is experimenting with the 414M rear arms, but they make the wheelbase BARELY illegal (261mm) even in the forward setting (Same guy is also using 414M caster blocks with torque rods - something for me to try next). I would rather shave the rear section of the Evo 2 arms to get a little more room for adjustment. The other benefit of this is that the front universals are almost straight and the rears are closer to being straight. This greatly affects power transmission/efficiency, outdrive and universal life, and handling. This is one reason that I feel that the Evo 2 drivetrain is inferior to my mutant TB01. Like the Yokomo which has forward swept universals, the outdrives will wear very quickly if not lubed. If an outdrive develops a notch, CHUCK IT. Even the slightest notch will make your car hop under acceleration. I would still like to rework the gearboxes to see if any more efficiency can be freed up. Rear diff maintenance is CRUCIAL on this car. The driveline is so brutal that diffs don't even last that long in STOCK. Using the old David Jun trick of a Tamiya 5x11 bearing will make things last longer because the thrust goes out before the rings. Only use Tamiya bearings for this application because even Boca bearings do not hold up as well under the sideload.

The main problem that I found with the Evo 2 was a lack of corner speed. The car just wanted to stop and pivot instead of carve. Adopting Surikarn's method of raising roll-center, the chassis becomes more progressive at the limits, breaking away smoothly instead of suddenly. Take out a little caster for sharper turn-in. Rear swaybar for the rear to come around a little harder and get rid of some of the on-power looseness. Bingo. It could still use some tweaking, but it's not my car.
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Last edited by ruf; 08-20-2002 at 08:43 AM.
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Old 08-19-2002, 04:18 PM   #332
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I use a small drop of Loctite to keep the outdrives in and the diff cover attached. The new hardened 88T spurs are AWESOME... The only reason I would think about going to a Cross/Tobee gear adapter hub would be for mod gearing.

Quote:
Originally posted by wyd
As for gearing just run the stock 88 tooth for everything. The 72 is too small for almost anything.

The EVO2 is a really nice car. I had one and it was pretty fast but I didn't car for the loose outdrives which kinda is a poor design on a car of that quality. Other than that is can get the job done.
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Old 08-19-2002, 04:19 PM   #333
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VERY sensitive to droop. Most cars are. The thing with the Evo 2 is the default amount of droop is STUPID large.

Quote:
Originally posted by Aluma
the evo2 must be extremely sensitive to droop... I'm gonna play with that now and see if that can be the culprit all along.
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Old 08-19-2002, 11:41 PM   #334
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aluma:
u mean the car understears with NO rear droop ??

hm ...... have u tried leaving rear droop to 1-2 mm ??
its normal for tc to have 1-2 mm nothing more or less ...

try messing aorund with the front droop ..... see if thers any diffrence

btw ... where do u try ur car ??? in front of ur house or at the track ??

try it at the track cause ur discription of understearing when u have NO droop seemed wierd to me ....... normally with no rear droop the car understears when it starts to turn then suddenly it breaks traction going into a 360 spin-out
or if it does not spin out u will slide to the outer barrier

btw is the overstear on power of off power??

with rear droop ( not too much) the car will feel more planted troughout the turn but if u accelerate out of a turn u will overstear then suddenly strighten out ........ ( needs a bit of gettin used to ....)

maybe the overstear u discribed is that it will overstear too much on power???
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Old 08-20-2002, 07:02 AM   #335
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I only test it out at the track with traction additive to the entire track(grape soda) And yes.... I've got absolutely no droop front or rear right now... and it will not spin its tail out no matter on power or off power... I did add two washers to the front of the rear block and one to the rear block to gain caster and lower roll center a bit. the front has no spacers whatsoever.

I used to have bout 4 rear from associated droop gauge and 3 front droop...thats when it would go CrAZy oversteer off power and just a bit on power and straighten out after a bit. and trust me, the way i got it up right now this this is TOO planted...i have to slow down a bunch so it'll make the turn just right...it'll be a while before i can go test again...but I think i'll try rufs setup...maybe that'll be the ticket.
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Old 08-20-2002, 07:04 AM   #336
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Ummm, RUF... whats a gearbox shaved? what does that do and what does it entail?
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Old 08-20-2002, 08:31 AM   #337
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You have to shave (enlarge) the notch in the gearboxes if you are going to shim the hingepin blocks. They will hit otherwise.
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Old 08-20-2002, 08:40 AM   #338
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"Caster" in the back is called "anti-squat". If you put shims underneath the hingepin blocks, you are raising rollcenter, not lowering it. 3/4mm droop in TC3 gauge is too large as you found out, but no droop at all is too little (probably about 11-12 on TC3 gauge scale). The car will not transfer weight especially in transient sections and like you noticed, you will lose corner speed. I usually run anywhere from 4-8mm of droop (TC3) until the car will carve, but not unload in transition.

Just to make sure we're all on the same page, droop measurements using the TC3 gauge are opposite of typical droop numbers and can also vary depending on where you measure from. I typically take my measurements from the lowest/outside part of the arm, but on some cars, the bottom kingpin is a better reference. Typically I set my cars up with about 2-4mm of droop above static ride height.
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Old 08-20-2002, 03:33 PM   #339
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yeah, i measure from the bottom of point furthest out...using a nitro TC3 tool. ...i'll try it on the kingpin if possible...

Hey RUF and anyone else close by.... my local track (Harlingen G.E.A.R.S. club) is having a HUGE race November1st and 2nd for onroad elec/nitro + offroad elec/nitro.... we have a 55X90ft onroad course and a HUGE (750ft of driving) offroad track that was just built like a week ago.

If you're interested I can email ya an entry form and anyone else who might want to come down to Deep South Texas (in Harlingen)for a great race! There will also be a 1:1 car show and carnival and other stuff going on at the same time in case you get bored waiting for your time to race. we usually run 70 cars every other weekend on normal race days...lots of guys down here to race with and even visitors from san antonio and victoria come down too.

oh yeah, you can also check out our boardGEARS

theres pictures there of the track too
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Old 08-20-2002, 04:10 PM   #340
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Ugh. Owning a hobby shop means that I don't get to travel very much...

As for races, we are hosting the ROAR Region 9 Regional Championships this coming weekend. Check out www.reflexrc.com for info and sign-up.
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Old 08-21-2002, 12:49 AM   #341
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good luck aluma .....
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Old 08-28-2002, 06:20 AM   #342
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Hey RUF, i tried out your setup....but it just has way too much understeer.... I can almost get the rear end to swing a bit if i'm going full speed and turn/brake... have to slow down tremendously to even take a sharp turn even outside in the dusty parking lot. also noticed that on high speed turns the car is unsettleing...it leans in for the turn but then jumps a bit and leans somemore and repeats. Hmmmm.... this thing is drivin me NUTS
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Old 08-28-2002, 09:54 AM   #343
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Aluma - I'm sorry the setup didn't work out for you. We had our regional race this weekend and we blew off the track. This blows off all of the rubber "groove" that has been setting up over the last couple of months so traction is REALLY REALLY low initially. As the weekend wears on, the groove starts to come back. I noticed that for the initial few runs, I was having to set up my friend's car a little stiffer in the rear to get it to pivot more on turn in. I suspect that the car's weight balance makes push the dominant characteristic when traction is low. Once the track started grooving, I balanced out the chassis again by stiffening the front since the new layout had a lot more high-speed corners and the chassis was bottoming out on roll.

What kind of surface do you race on? What body do you use? Tires? Can you take a picture of your car? I will post some detail shots of my friend's so that you can see exactly what I'm doing. Keep in mind that no setup is perfect and it requires that you tweak it for all factors: track surface, layout, driving style, opposing drivers, heat, tires, body, wear, radio, etc. I think that the setup I posted is probably just WAY off for your track and/or your radio settings.
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Old 08-28-2002, 11:33 AM   #344
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well, the track is a 55X90ft slab of asphalt next to an offroad track. its rather old and has lots of bumps, sealed cracks and grooves. But, we do blow it off every race day and spray it with grape soda. I use HPI 27R's to race with or my Tamiya type A's. Bodies... hpi stratus, proline jetta, hpi bmw m3 coupe(the weird stationwagon like one), beetle, and tamiya altezza(havent used it to race yet) I setup the following way: i have front ball diff, and Ta04R front hubs/ carriers/caster rods...

front: 30wt/red middle hole, -2camber, 0toe,5caster with 2mm spacer under the front's rear hingeblock....3droop on nitro tc3 onepiece gauge taken from outer hingpin.ride height comes to5mm...with more preload on motor side

rear: 30wt/yellow middle hole, -2 camber, 0toe(comes that way), 5caster with 2mm spacer under the rear's front block...4droop from the outer hingepin.5mm ride height.more preload on battery side to compensate for batter weight.
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Old 08-28-2002, 02:38 PM   #345
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So wait, I'm confused here. Did you try the ENTIRE setup or just parts of it? The front oneway and the 1-degree toe-in rear block is a crucial part of the setup.

Are you checking tweak? Or are you just compensating for weight? If so how?

The jumping is probably your chassis bottoming out. You are running very soft on your spring rate and shock angles. This is a good thing for the bumps on your track, but your roll stiffness is compromised. Raise your roll centers so that you can keep your suspension compliance for soaking up bumps but still corner relatively flat. Swaybars will help too. My mentality is that I want as much roll as possible without upsetting the chassis (either from bottoming out or transition). I also think that you probably have a little too much droop which is letting your chassis roll over a lot more than it wants to.
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