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Old 10-16-2009, 05:26 PM   #1276
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Center springs in the range 17.5 to 30. On outdoor asphalt I like maximum suspension travel. It tend to use the center spring light enough to just keep the chassis off the ground.

Battle Axe 2.0 offset pod

Here is a pic with some red Hyperdrive hubs and nut. You can't put too much red on a CRC car.
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Old 10-16-2009, 06:07 PM   #1277
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John

which losi car does the shock on the genx 10 come from ?. I want to make sure i order the right springs ?. Also what weight is the stock spring ?.

Last edited by hippie; 10-17-2009 at 09:06 PM.
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Old 10-16-2009, 06:09 PM   #1278
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Hi John. I've started going through this thread and it's been interesting reading. You've done some brilliant work here so well done!

I have some questions about the 3-link rear end. Is there a relationship between the side links and the centre link in terms length and angle of the links? Also are longer links preferred and what is the advantage there?

Thanks and keep up the great work!
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Old 10-16-2009, 07:53 PM   #1279
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I think the springs are from the jrx-s Type R. Stock spring is a 25 lb spring LOSA5352. Losi sells them in 2.5 lb incriments. I am using a 12 lb AE spring on my BA and it seems pretty good.

Just got the new offset bottom plate on tonight. Will give it a test tomorrow.
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Old 10-16-2009, 07:57 PM   #1280
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Hippie-The shock is from the JRXS or JRXS type R

Roll Steer
You can mount that side link up. When you do this you add roll steer. That means as the car rolls the angle of the rear axle changes with respect to the car. It steers out a little with roll. This tends to free up the car. You can determine if you like this effect by just spacing that forward ball stud up .1 inch on both sides.

My 3 link cars use substantial rear roll steer out to very good effect. It makes the car nimble.

veecee-First Thanks. Yes the angles and length of the links have importance on the three link. With long links unwanted motion of the pod is prevented. Note CRC is now providing long links. For Example when a typical pan car hits a bump the motor rotates quite a bit. In order to come back down to ground the suspension must not only push the tires down but it must unrotate the motor. This causes inefficiency and loss of suppleness in the suspension and ultimately loss of forward traction. On the three link, motor rotation is very minimal. The tires (and motor) return directly to ground and forward traction is much better; there is more forward traction.
All pan cars have antisquat built in. Antisquat is the tendency of the suspension to lift the back (and the front) of the car on power. It transfers weight to the driving wheels on forward throttle. On the typical pan car the antisquat forces are dissipated by the center shock. The back cannot lift the front until the shock fully elongates. This means there is ineffective front to back weight transfer on forward throttle. If the center shock fully elongates it creates quite a disruption to the car on corner exit. On the 3-link the weight transfer is instant on forward throttle. There is a short video describing antisquat on my web site. The angle of the side link and top link affect the instant (longitudinal) center and thus the antisquat in a similar manner that front suspension arm angles affect instant center and roll center. I have the 3-link set for about maximum effective antisquat on a pan car.

The figure shows a car with 70% antisquat. % antisquat is a construct of Author Carrol Smith in the book "Tune to Win". If the line from the tire to the instant center reaches the center of gravity of the car then 100% antisquat is obtained. My experiments show antisquat levels greater than this (100%) to be of less use on a pan car. Cornering becomes more difficult. The car becomes hard to drive.

Another method of measuring antisquat is the torque arm of the pod (pivot to axle)/pivot height. Thus the shorter the torque arm the more antisquat. The T-plate car with the most forward traction and by no coincidence the most antisquat is the rear pivot T-plate cars like the Woods brothers and Superior Spectre oval cars that I tested earlier in the thread. You can certainly feel the better forward traction on the outdoor track. And then the 3-link kicks its butt. Differences are easily seen in lap times and on radar at the end of the straight.

John-Your hubs are on the way.
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CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-pitch-instant-center-antisquat012-resized.jpg  
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Last edited by John Stranahan; 10-16-2009 at 11:59 PM.
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Old 10-17-2009, 05:00 PM   #1281
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Thank you guys for the answers .




John i know you said your nerf wings were not designed to work with the CRC long side links. But i noticed they will fit on top of the wing . Because the hole is there . My ? is how will it affect performance by mounting the link on top of the wing , instead of lower on the chassis ?.

Last edited by hippie; 10-17-2009 at 09:06 PM.
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Old 10-18-2009, 03:16 AM   #1282
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I said I'd post how my 12th car with panhard bar worked last week.
The only problem I found was that I lacked vertical damping over bumps but I'm working on that atm.
The car's rear end was very stable allthough I had an incredible amount of off power steering (remember I'm driving the A123's and they're 150gr lighter than NiMh, about the same as Lipo). Slight understeer on power but that will be taken care of next time.
The mechanical grip of the rear was amazing, even in fast chicanes the rear wouldnt slide out the least, I didnt have a rear end slide the complete day... not even with a busted rear tire which is very critical on a 12th.
The A123s also held up awesome, 10min driving and 15 minutes of charging what could be better.

Now, lap times, there were 2 12th scalers at the track so grip wasnt all to great but my friend was running 16,4 seconds and I was doing about 16,05 at the end of the day so the car is promising.

After cursing on the Ride height shims I decided to draw up new ones which dont invoke the tweak that the CRC ones do. The problem is where the support of the arm is, tweak is introduced when the front isnt supported decently on the sides (I usually need to add a 0.25 one on one side extra to have the front height the same left and right . Mine have support on the sides instead of front and back.
Milled em yesterday, bolted them under the arms and measured the left and right arm to the ground. I am within 0.02mm using a digital caliper .
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Old 10-18-2009, 09:34 AM   #1283
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First test results of the offset pod. Started out with two cars set up for 13.5 1 cell to have a somewhat controlled test. Motor and battery were different, so it wasnt perfectly identical, but pretty close. Had the same setup on both cars.

First session the track was pretty slick. The offset car was very loose, seemed to skate over the top instead of rolling and digging in. Normal car was dialed right away. Added a little preload to the LR spring (2 turns) car started to work better. Turned in faster than the centered car. Lap times were similar. I did not expect the offset car to turn better. When I scaled the two cars, the offest car had 1 oz extra the LR and RF over the centered car. Cross weight on the offset car was 62% vs 54 % onthe centered car. Could get 3.7's from both cars. Was still .1 off the pace.

Decided to run the offset car as a 10.5, so swapped the motor. Car started to push. This is what I would have expected with the offset pod, not the better steering like on the 13.5. Took out the preload I added previously to the LR and the car was working well. TQ in this class has a 3.33 best lap. I pulled one 3.36 lap. My driving was not consistent enough and was down 2 or 3 laps over race distance. Oval is brutal is you are off just a little bit.

Did not provide a big change as expected. Looks promising in that it did add LR weight which is what I was looking for. Need to build another car so I can have two that are identical. I also have more batteries now so I can do more testing instead of 1 run per hour.

John
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Old 10-18-2009, 10:00 AM   #1284
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Hippie-I had answered that in a longer post. Here is the excerpt. Take a look at the quote below.

John-did you get a chance to tinker with the rear tire hardness on the offset pod car. I think this is going to be a needed change with it to see a benefit.


Dirk-Great news. Thanks for the report. I will look into that tweak situation. I handle my CRC ride height spacers a little differently. I sand the nubs off the top so that it is flat and then leave the screws that hold the caster block alone for each ride height change. I'll take a look at my world GT car to see if I still have the tweak issue. Nice spacers.

If there is too much rear grip, you can raise the front of your side links a little and add some roll steer. Otherwise the car sounds like it does what is promised. More forward and side grip on the rear in difficult conditions.


Quote:
Originally Posted by John Stranahan View Post
Hippie-The shock is from the JRXS or JRXS type R

Roll Steer
You can mount that side link up. When you do this you add roll steer. That means as the car rolls the angle of the rear axle changes with respect to the car. It steers out a little with roll. This tends to free up the car. You can determine if you like this effect by just spacing that forward ball stud up .1 inch on both sides.
My 3 link cars use substantial rear roll steer out to very good effect. It makes the car nimble.
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Old 10-18-2009, 10:33 AM   #1285
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Quote:
Originally Posted by John Stranahan View Post
Hippie-I had answered that in a longer post. Here is the excerpt. Take a look at the quote below.

John-did you get a chance to tinker with the rear tire hardness on the offset pod car. I think this is going to be a needed change with it to see a benefit.


Dirk-Great news. Thanks for the report. I will look into that tweak situation. I handle my CRC ride height spacers a little differently. I sand the nubs off the top so that it is flat and then leave the screws that hold the caster block alone for each ride height change. I'll take a look at my world GT car to see if I still have the tweak issue. Nice spacers.

If there is too much rear grip, you can raise the front of your side links a little and add some roll steer. Otherwise the car sounds like it does what is promised. More forward and side grip on the rear in difficult conditions.
Thank's john i did not understand thats what you were talking about . So you would raise just the FR & not the FR & RR in equal amounts ?.
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Old 10-18-2009, 11:52 AM   #1286
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Originally Posted by dumper View Post
My Gen X 10 setup from Vegas

http://www.teamcrc.com/crc/downloads...ICsetupWGT.pdf

Any questions, feel free to ask.



dumper
What would you compare the front 12th spring to the wgt tweak springs?
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Old 10-18-2009, 09:50 PM   #1287
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Dumper-Thanks for the setup link. New question above.

Hippie-Yes raise just the front to add roll steer and simulate nerf wings plus long CRC links.

If you changed all three rear pivots (center and 2 sides) up .1 inch and you had the Nerf wings or spacers to raise the front .1 inch, chances are good, from my testing, that you would notice no difference in handling or difference so slight it would be hard to notice. Raising that center pivot .1 inch would be trouble. You would need a spacer and a custom cut center post. If you just raise the two outer links pivots up then you would probably have binding or tilting of the pod on roll and poor driving car. These three rear pivots should be in the same plane for freest function. I have not actualy set up a car with two high rear link pivots and a normal center pivot. This would be easy to do. Set it up without shocks and see how it moves on bump and roll.

My test was lowering these three rear pivots and noticing no change. Also I have changed the height of my Panhard bar up and down and noticed no change. We don't really have control of the rear roll center with these changes.
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Old 10-19-2009, 06:48 AM   #1288
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What would you compare the front 12th spring to the wgt tweak springs?

The 12th scale front end springs and kingpins, react quicker and keep the front end flatter due to the fact that have less travel. With these cars having so much traction, they always feel kind of "stuck" on the carpet, so I have found that going to these springs in the front help keep the front end feeling lighter and less "stuck".
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Old 10-19-2009, 07:14 AM   #1289
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The 12th scale front end springs and kingpins, react quicker and keep the front end flatter due to the fact that have less travel. With these cars having so much traction, they always feel kind of "stuck" on the carpet, so I have found that going to these springs in the front help keep the front end feeling lighter and less "stuck".
Thats exactly the problem im having. Someone who was at vegas said our track has "vegas grip"..Here is what i had to do to not have the "stuck" feeling...Green front springs, 5 deg blocks, one caster shim arms front, wide track width, 17.5lb center spring, red tweak springs, thick damper tube fluid,1/4" front sause. I CA'ed the front sidewall. I had white, 10deg block, full caster, middle track width, 17.5lb center spring, red tweak springs, thick damper tube fluid. The car would dive so hard that the rear would lift.

The way the car is now its feels like it needs more on power steering. Should i add some caster back? How about damper tubes or tweak springs?
Thanks for the help.
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Old 10-19-2009, 10:15 AM   #1290
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John I just placed a order on your site for a H/D bottom plate .


As for your info on roll steer. i think i will try the car first with the standerd links. Before i order the longer links . I googeld the conversion for .1 inch . It comes out to 2.5mm . So that would be just about the same as mounting the longer (CRC) links on top of your wings .

I just ordered the longer ( CRC) links & side link balls, and some LOSI springs in 17.5, 20 & 30 spring rates . So i have some tunning options . I really looking foward to running this car for the first time .

Last edited by hippie; 10-19-2009 at 10:49 AM. Reason: NEW INFO
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