District track Tune? what to do?

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derbyfever
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Re: District track Tune? what to do?

Post by derbyfever » Mon Feb 02, 2015 11:30 am

OK.wegave up on the original car. Madeca duplicate looking car. (Axle hole relocation didn't quite have accurate drilling. New body is spot on with drilled holes. Our dominate front wheel is proper left side . Should the dominate rear be right side? Shift a bit if weight to favor the right side rear or is does it matter which rear is dominate? I'm shooting for 3/4 - 11/16 COM.



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Re: District track Tune? what to do?

Post by Stan Pope » Mon Feb 02, 2015 1:06 pm

derbyfever wrote:OK.wegave up on the original car. Madeca duplicate looking car. (Axle hole relocation didn't quite have accurate drilling. New body is spot on with drilled holes. Our dominate front wheel is proper left side . Should the dominate rear be right side? Shift a bit if weight to favor the right side rear or is does it matter which rear is dominate? I'm shooting for 3/4 - 11/16 COM.
Since with centered ballast, the opposite (right) side rear will carry 1/2 of the car's weight, and the left side will split 1/2 the weight between the DFW and the rear wheel behind it. Some folks prefer that the rear wheels carry the same amount of weight. To accomplish that, they shift ballast slightly toward the DFW side of the car. It doesn't take much of a shift to equalize the rear wheel load.

This shift also places the CM more solidly inside the "support triangle" which helps stability, but the effect is pretty small.

On the other hand, shifting the CM away from the DFW side of the car pushes it toward the edge of the support triangle and reduces stability. I'd avoid that.

You said earlier that your bent axles were "weird." What symptoms did you observe?


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Re: District track Tune? what to do?

Post by derbyfever » Mon Feb 02, 2015 5:23 pm

Thanks for your answer Stan. As far as our bent front steering axle, we tried the 2.5 degree bend. 2.5 Probably too much for this long track. The 2.5 dfw on the test board seemed to bind with its extreme angle coupled with rubbing car body and the yard stick rail. We've opted to drill the positive camber of 1.5 and a very very slight toe in. The final steer will get accomplished with mild bent axle. Thanks STAN!
We're aligning rears tonight. Bias weight harness's have been made and new test board also built. I think we will go to first night of Districts before our race next night to check out some competition and track conditions before final drift setting gets glued in.



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Re: District track Tune? what to do?

Post by pwrd by tungsten » Mon Feb 02, 2015 10:19 pm

derbyfever wrote:Thanks for your answer Stan. As far as our bent front steering axle, we tried the 2.5 degree bend. 2.5 Probably too much for this long track. The 2.5 dfw on the test board seemed to bind with its extreme angle coupled with rubbing car body and the yard stick rail. We've opted to drill the positive camber of 1.5 and a very very slight toe in. The final steer will get accomplished with mild bent axle. Thanks STAN!
We're aligning rears tonight. Bias weight harness's have been made and new test board also built. I think we will go to first night of Districts before our race next night to check out some competition and track conditions before final drift setting gets glued in.
Good to hear on the new car. Always good to start with a firm alignment on the rears. I would keep COM at 5/8-3/4 if you can. However no big deal if it is a bit off.

DFW bend is no big deal... Your technique will work great though. Just so you know. I use over 5 degrees on the DFW but 2.5 is fine as is your method.

For the case of 2.5 degree bend you move the axle from 3 o clock (most steer) to 6 o clock (no steer). You run it down a 4' long board to see how many inched of steer. Most of my cars are in the 2.75" range on a 4 foot run.


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Re: District track Tune? what to do?

Post by derbyfever » Tue Feb 03, 2015 12:10 am

Our COM is right at 11/16. I think that's the most aggressive this build will go using canopy lengthwise and body design. 4 of the 3/16 cubes at far back of car. Its a spoon type hour glass shape ..5/16 thick. I've never seen an extreme bent front axle car on the podium at our district races..we've been there 4 years now. This is 5th and last year. I got the drift at 2in in 4 ft. Front axle hole drilled at 1.5 approx.. Utilized natural bend for steer..wasn't enough.. So used shims(pain..lol) kicked the axle down a bit more basically 2 parchment paper shims at top and 2 shims rear of axle( sitting around 2 degrees positive camber ( I think)...what's the benefit of running 2.5 ,3 or even 5 degrees on dfw? What's best for my COM and long track ? I checked rears with bias weight of .85 oz with Stan's wire rig..I can't detect any deviation from rail either side. I guess I got straight holes and axles to match... I think I'll trow in a wacky axle to check the bias weight test. Need to see it run wacky..thanks for your input pwrdbytungsten!!
Lol



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Re: District track Tune? what to do?

Post by pwrd by tungsten » Tue Feb 03, 2015 4:26 am

derbyfever wrote:Our COM is right at 11/16. I think that's the most aggressive this build will go using canopy lengthwise and body design. 4 of the 3/16 cubes at far back of car. Its a spoon type hour glass shape ..5/16 thick. I've never seen an extreme bent front axle car on the podium at our district races..we've been there 4 years now. This is 5th and last year. I got the drift at 2in in 4 ft. Front axle hole drilled at 1.5 approx.. Utilized natural bend for steer..wasn't enough.. So used shims(pain..lol) kicked the axle down a bit more basically 2 parchment paper shims at top and 2 shims rear of axle( sitting around 2 degrees positive camber ( I think)...what's the benefit of running 2.5 ,3 or even 5 degrees on dfw? What's best for my COM and long track ? I checked rears with bias weight of .85 oz with Stan's wire rig..I can't detect any deviation from rail either side. I guess I got straight holes and axles to match... I think I'll trow in a wacky axle to check the bias weight test. Need to see it run wacky..thanks for your input pwrdbytungsten!!
Lol
11/16th is right on (disregards my earlier note about 11/16).... it is in the zone 5/8-3/4. You do not need an extreme bend on the DFW. Assume track is in 40-42 foot range aluminum? If that is the case it is not a long track. Just a full size one :-). Many league racers have a larger bend but it is not critical at all....

Your steer is light. it is hard to say without track tuning it is just a guess... If you turn too hard you will go slower. My guess is the car will start wiggling at 30-35 feet. That may actually be perfect or it may leave a tad of speed on the track...

If you had track access you would bring your tuning table and record the setting, run the car down the track and watch where it wiggles. if it runs straight back off the steer, run it down the table to record steer and down the track until you see it wiggle just as it passes the finish line. Then record that time. Lighten the turn and see if it goes faster or slower the less turn you give it.... Get the wiggles out as a base line and record that then tune more and less stir around that point to see if better times result...


Disregards the below. It is just what to do on a really long track. :-)

If it is longer then this (think 100 feet or more) at some point you go with a middle weighting and you shift the weight all the way to the DFW side and/or drop the forth wheel and at some point you go with full weight wheels.


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Re: District track Tune? what to do?

Post by derbyfever » Tue Feb 03, 2015 11:08 am

Yeah, I wish we could have access to this track, but its restricted to race day only. They lock it up all year until districts. We can practice tune on the packs track but its plastic side rails.you think 2 1/2 inch drift in 4ft might be the magic setting? My Fever is increasing. Almost there. :pray:



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Re: District track Tune? what to do?

Post by pwrd by tungsten » Tue Feb 03, 2015 1:48 pm

derbyfever wrote:Yeah, I wish we could have access to this track, but its restricted to race day only. They lock it up all year until districts. We can practice tune on the packs track but its plastic side rails.you think 2 1/2 inch drift in 4ft might be the magic setting? My Fever is increasing. Almost there. :pray:
Hard to pick a turn rate. However I would sleep better with 2.5" than 2" because 2" is light.


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Re: District track Tune? what to do?

Post by derbyfever » Tue Feb 03, 2015 6:49 pm

Uh yeah. I'm getting sleepless. So when tuning drift and checking rears etc on our test board,( that we have set at 1half inch drop/ slope per ft. (6ft long board),,))should graphite be added for proper accuracy? I've been aligning and setting drift while totally dry of lubricant.



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Re: District track Tune? what to do?

Post by ngyoung » Tue Feb 03, 2015 7:47 pm

I would err towards 4" over 4'



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Re: District track Tune? what to do?

Post by Stan Pope » Tue Feb 03, 2015 8:22 pm

derbyfever wrote:Uh yeah. I'm getting sleepless. So when tuning drift and checking rears etc on our test board,( that we have set at 1half inch drop/ slope per ft. (6ft long board),,))should graphite be added for proper accuracy? I've been aligning and setting drift while totally dry of lubricant.
I always include lubricant if the wheels are turning!


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Re: District track Tune? what to do?

Post by pwrd by tungsten » Wed Feb 04, 2015 12:56 am

derbyfever wrote:Uh yeah. I'm getting sleepless. So when tuning drift and checking rears etc on our test board,( that we have set at 1half inch drop/ slope per ft. (6ft long board),,))should graphite be added for proper accuracy? I've been aligning and setting drift while totally dry of lubricant.
Check your PMs. I sent you some helpful info....


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Re: District track Tune? what to do?

Post by pwrd by tungsten » Wed Feb 04, 2015 12:58 am

derbyfever wrote:Uh yeah. I'm getting sleepless. So when tuning drift and checking rears etc on our test board,( that we have set at 1half inch drop/ slope per ft. (6ft long board),,))should graphite be added for proper accuracy? I've been aligning and setting drift while totally dry of lubricant.
How long is your track at Districts?


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Re: District track Tune? what to do?

Post by derbyfever » Wed Feb 04, 2015 9:57 pm

Not too sure on exact length
I'm looking to up load some video here of last years runs so uoi guys can see our district track. Pwrdbytungsten..thanks
I'll check my PM inbox.
With the rears at 2.5 neg and the front positive, I'm getting dfw side rear to follow a hair just under 1/8inch off rail.is this too much gap? The body has been shaved 1/16 at dfw. Is shaving off the 1/6 at dfw even needed when the wheel are opposite camber like that? And What is the "standard" width of pwd tracks center rail anyway? Thanks for all your help guys!



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Re: District track Tune? what to do?

Post by derbyfever » Wed Feb 04, 2015 10:11 pm

Our drift in 4 ft,is averaging 2.75 now some 2.3..some 3s. I did do some math on it. Our board is MDF built at 6ft long by 18 inches wide with side rail supports. Built sloped.
( didn't want to flip board over for drift setting and have yard sticks fastened 4 inches from inside edge along length .It seems real smooth and is level side to side BUT getting different measurements from say 6 inches away from yard stick.compared to 8 inches. Farther away from.me is less drift and closer in (just those 2 inches) its measuring 3 inch to 3.75 drift. I must have a slight Swale in the board . Sure looks nice though. And heavy .



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