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Old 01-27-2015, 06:05 AM   #1636
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Old 01-27-2015, 06:07 AM   #1637
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For a couple of decades I subscribed to the idea that the front of the pod lifted under acceleration. I visualized the the motor pinion wanting to crawl up the spur. If you look at that, it's easy to see and think that. There's a little more to it. You are accelerating a car so fast with a force point coming from the axle centerline which happens to be above the pivot ball at the front of the pod. That acceleration force at the axle is greater then the effect of the pinion wanting to crawl up the spur, therefore the pod collapses under hard acceleration. This why the car, with too soft of a center spring, will bottom out and veer into a corner with relatively good grip track.
Brian, have you experimented with changing the anti-squat? The height of the pivot balls determines this.

Viewing from the side of the car, imagine a line going from ground level directly below the axle on the center line of the car (between the two rear tire contact patches) through the center pivot ball. If that line passes below the CG, then the car will squat under acceleration. Raising the center pivot ball will reduce the squat. Unfortunately all the other pivot balls would need to be raised the same amount (on a car with the "normal" link rear), which raises the rear roll center, and this might be more detrimental to handling than any gains from adding anti-squat.

Of course, there are also inertial effects happening as the motor spools up, and that isn't affected by the anti-squat. I'd guess that is pretty significant.
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Old 01-27-2015, 06:13 AM   #1638
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Anyone know when CRC will be shipping this car again?

Thanks
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Old 01-27-2015, 07:54 AM   #1639
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Anyone know when CRC will be shipping this car again?

Thanks
Last thursday I contacted CRC to check on the status of my pending order for a new worlds edition car. The helpful guys there advised that they were in the process of packing up a batch of worlds edition kits in hopes of having some ready to ship out early this week. With some luck, the big brown truck will be dropping a nice box on my doorstep within the next couple of days.
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Old 01-27-2015, 09:22 AM   #1640
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But, I remember an IIC where you won just about everything else...
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That was one hell of a year...very impressive drives!
That was a good year. I've learned a "ton" since then. Now, it seems like I just knock on the door, but no one answers.

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finally - a well respected, open minded, and knowledgable guy has tried out running spec 1/12th scale tires and reported his findings. THANK YOU Brian for doing us all that favor and for sharing your observations and wisdom. Looks like I'll need to order me up a couple of sets of Lilac tires so that I can try and "prove" Brian's findings to our local club.......in hopes of convincing the guys that running spec 1/12th tires could simplify and grow our 17.5 1/12th scale class.
Thanks! A handful of us are going to race them this Wed night in stock. I am going to dial up the car for a little bit more steering and see what happens. Initially I found them to be only about a 1/2 lap slower then race foams and the wear is excellent.

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No Brian, you are not talking down to the masses. I don't take any personal offense to your information or method of communication. Too bad we didn't get any of this from our great pro mod drivers from 1995 on to 2009. The USA would have better performance at the WC level.

Regarding the spec tires, it is just me. I like the green/blue rears and the blue/double blue fronts so well I don't want to give them up.
Yep, quality info was like treasured gold and never shown. I am tired of that and I simply don't care. If you beat me with skill and better set up, I don't get all butt hurt. I'm more like: good job, guess I'll get back to work! Lets see what you did and see if it works for me. CRC is sitting on a great car, I want to clear the air of the difficult chassis' of the past two years.

I like my blues too!

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Brian, have you experimented with changing the anti-squat? The height of the pivot balls determines this.

Viewing from the side of the car, imagine a line going from ground level directly below the axle on the center line of the car (between the two rear tire contact patches) through the center pivot ball. If that line passes below the CG, then the car will squat under acceleration. Raising the center pivot ball will reduce the squat. Unfortunately all the other pivot balls would need to be raised the same amount (on a car with the "normal" link rear), which raises the rear roll center, and this might be more detrimental to handling than any gains from adding anti-squat.

Of course, there are also inertial effects happening as the motor spools up, and that isn't affected by the anti-squat. I'd guess that is pretty significant.
Several years ago I had a lowered pivot ball for t-bar cars I designed to make more rear grip. It was a crutch to get us past the pink/blk on Jack days with the hell fast for 6.5 minutes and then turned into a miserable pos. That is my only real experience on elevating the pivot ball. From that, I would conclude that lowering the pivot ball (and all the links) will make more rear grip. Elevating them will free the rear. But I do not play with that anymore. When Dave drove CRC, he played with it in mod to get the car to hold on longer. I understand far more now that corrects squat then going after the pivot ball.
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Old 01-27-2015, 10:00 AM   #1641
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The lowered rear pivot ball for the CRC 3.2 and the T-force was a great modification. It never occurred to me that it was because of tires going dry. 4-5 years ago I was running Magenta/Yellow and genuine black can paragon, so we had grip for hours.
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Old 01-27-2015, 02:40 PM   #1642
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I ran the spec tires at my local tack as blues and greens were back ordered so I thought I'd give them a try. On our old lay out with low-med grip I lost .1-.3 in my lap average and was 5 seconds slower on the same lap as blue/blue combo. Only changed my center spring and oil for a little more steering. When the lay out was changed is when I had issues. Wasn't horrible but car was sliding a little more and I could only get to .4-.5 per lap behind the leaders. Now if we were all on the same tire it would not have been a big issue. I got nothing against spec tires at all. If it gets more people in it great but don't think it's going to slow the fast guys down at all. If anything I say it's going to make set up and driving more important. But back to blues/ greens till there is a spec tire rule.
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Old 01-27-2015, 03:59 PM   #1643
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I wouldn't mind spec tire for 17.5 but really now we have a two option spec tire. You have two fronts to choose: blue and XX Blue and two rears to choose, Blue and Green. Really don't need anything else.

I freaking love WGT with the spec tires. I really can't understand why that isn't one of the biggest classes on earth.
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Old 01-27-2015, 04:43 PM   #1644
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Brian, have you experimented with changing the anti-squat? The height of the pivot balls determines this.

Viewing from the side of the car, imagine a line going from ground level directly below the axle on the center line of the car (between the two rear tire contact patches) through the center pivot ball. If that line passes below the CG, then the car will squat under acceleration. Raising the center pivot ball will reduce the squat. Unfortunately all the other pivot balls would need to be raised the same amount (on a car with the "normal" link rear), which raises the rear roll center, and this might be more detrimental to handling than any gains from adding anti-squat.

Of course, there are also inertial effects happening as the motor spools up, and that isn't affected by the anti-squat. I'd guess that is pretty significant.
Darn Howard, you beat me to it. I was going to suggest raising the rear roll center. My thought was raising the rear roll center meant raising the center pivot ball in the rear plus all of the links. The effect would be to shorten the distance of the thrust line of the rear of the car giving a smaller torque that forces the front of the pod towards the carpet. I did that on the IRS RugRat several years ago to fix a problem of lifting the rear inside tire. Worked on that car.

But I see that Brian has said there are better ways. But following your train of thought, using the shorter upper and lower pod plates available on the original XTi, you could get a steeper angle of the line so it would pass over the CG and stop the squat. Agree?
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Old 01-27-2015, 05:09 PM   #1645
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I wouldn't mind spec tire for 17.5 but really now we have a two option spec tire. You have two fronts to choose: blue and XX Blue and two rears to choose, Blue and Green. Really don't need anything else.

I freaking love WGT with the spec tires. I really can't understand why that isn't one of the biggest classes on earth.
On carpet the spec tires are fine but on asphalt they can be quite a chore to get to work. I think the biggest reason why is the same reason why 1/12th isn't more popular as well...granted 1/12th is more popular than WGT...and that is foam tires in general. Our hobby as a whole has grown more and more lazy and foam tire maintenance is anything but lazy. There are more reasons than that of course but that has to be one of the biggest if not the biggest. Conversely rubber tires are one of the big reasons why F1 isn't more popular...If someone could come up with a durable rubber tire that has near the performance of the foam tire I think the classes could really take off...unfortunately I also think that due to how light weight the cars are we'll never be able to get a rubber tire to work anywhere near as good as a foam tire.
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Old 01-27-2015, 05:12 PM   #1646
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I freaking love WGT with the spec tires. I really can't understand why that isn't one of the biggest classes on earth.[/QUOTE]

I'm with you, can't understand it. I love running WGT.
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Old 01-27-2015, 05:14 PM   #1647
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I was wandering what is a good tire size to start out with ( both front and rear ) for club racing
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Old 01-27-2015, 06:15 PM   #1648
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If you wander too much, you'll get lost!

I cut my stock12 tires 41.5/42.5 but I like them smaller.

I cut my mod12 tires 40.4/41.8

I cut my wgt on bsr's/crc's 51.5 front and rear, Jaco's 50.8.
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Old 01-27-2015, 08:43 PM   #1649
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The Spec tire debate is always interesting, I'd be more than happy to try it.
When I talk to people about racing 12th scale the confusion about tires seems to be the main problem that they have with the class. Over the last couple of years I've simplified things for myself by running Black front and Yellow rear everywhere. Effectively spec'ing myself and tuning the car to make it work. obviously it might not be the perfect combo everywhere...but its not far away.

Having said that, its time to order some more tires. I'm hearing so many good things about the Blue and Green compounds, I'm tempted to try some.
Question for you guys. What should I get? I race 13.5 on temporary carpet tracks starting with low traction building towards medium. Is it possible for me to spec myself with something that will work everywhere better than Black-Yellow?
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Old 01-27-2015, 09:42 PM   #1650
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Has anybody else tried the Ulti Z compound on carpet and basically had the car go from a perfectly good conventional weapon to a nuke? I may go broke buying these tires but I will be fast before I do, the grip is amazing.
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