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Old 09-23-2014, 08:31 PM   #781
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Speaking of VTA, I put the Evo4 gears in for the 2.294 internal, and it helped the car get down the straight a lot better. It didn't get as wound out as it did at 2.5 at the same final. Sounds crazy, but my buddy even noticed.
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Old 09-24-2014, 12:43 AM   #782
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Speaking of VTA, I put the Evo4 gears in for the 2.294 internal, and it helped the car get down the straight a lot better. It didn't get as wound out as it did at 2.5 at the same final. Sounds crazy, but my buddy even noticed.
Can you explain what you mean? If I did my math right, you dropped your FDR by 0.3 and the car was... faster? I mean, I'd expect higher top speed but slower acceleration. What was the crazy part?
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Old 09-24-2014, 01:35 AM   #783
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Can you explain what you mean? If I did my math right, you dropped your FDR by 0.3 and the car was... faster? I mean, I'd expect higher top speed but slower acceleration. What was the crazy part?
He changed the pinion/spur combination as well as reducing the internal drive ratio, keeping the fdr the same. You would then expect no change in speed/acceleration, the intriguing thing is that he and his buddy did notice a change. My wild guess is that he did a better job shimming for the newer gears which freed up the drivetrain
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Old 09-24-2014, 01:43 AM   #784
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Why would he change the pinion/spur combo?

The way I read it (based on the info in the post above and nothing else) is he has a longer FDR now, so he should have less acceleration but higher top speed. Not a huge difference for either but depending on track might be noticeable.
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Old 09-24-2014, 03:24 AM   #785
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Robk "Speaking of VTA, I put the Evo4 gears in for the 2.294 internal, and it helped the car get down the straight a lot better. It didn't get as wound out as it did at 2.5 at the same final. Sounds crazy, but my buddy even noticed"

Here he is saying at same final (meaning fdr). If thats true, he had to change the pinion/spur combination to compensate for the lower idr
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Old 09-24-2014, 05:54 AM   #786
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No i dropped teeth on the pinion to maintain the same fdr.

I know a lot of people have argued about internal ratios in the past. Engineers always say it makes no difference, and that you are stupid if you think it does.



I don't know, but it didn't seem so peak-y. Before, going one way or the other seemed like it either was rev'd out or not getting up to speed until too late on the straight.

Anyway, I like it. so I will continue to delude myself.
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Old 09-24-2014, 08:17 AM   #787
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Oh, right.

Missed that.

In theory it doesn't matter until you introduce details such as the fact that the mesh on the gears is not perfect, the fact that drag is dependent on rev speed (now you've got the motor spinning slower, but the drivetrain compensates by de-multiplying the revs less), who knows?

In a perfect world, it shouldn't make a difference, but this chassis has some problems with the drivetrain so I guess more investigation is necessary.

I am curious to chase if after the drivetrain is well worn in the difference is still apparent.
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Old 09-24-2014, 08:39 PM   #788
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FWIW, I had about 6-7 runs on the car before I changed gears, so we are at least comparing like to like.
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Old 09-28-2014, 12:58 PM   #789
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Second night with the EVO was... interesting. I was keeping the screws in my transmission cases just barely tight to keep things nice and loose. Well, during practice, the car started to suddenly lose rear traction like crazy. I pulled it and realized all 6 screws in the rear case backed out. Oops

During the qualifiers and main things were better. I had one of the fastest qualifier paces until I screwed up, but the car is still very capable. I switched from Tamiya springs to Spec-R 2.6F and 2.5R, which was definitely better.

In the main, however, our traction was WAY up (CRC carpet, humid evening), and mid-main my handling became a handful. A ton of steering, rear end breaking loose, the car basically dancing around the front tires. Just not balanced at all. I went over it after the race and nothing looked broken, so I'm not sure what happened.

I now switched to Yokomo pink and blue springs, I'll try them out this week and see how it feels. I need to play more with droop, I think I had too much in the rear, which could explain the situation in the main (was running 6.6F and 6R on Hudy droop gauge and blocks). Gonna go up to 7F and 6.4R to start. Most of our track records were on Yoko springs, so might as well try those. HPI silver or blue could be another test.
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Old 09-28-2014, 03:30 PM   #790
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Second night with the EVO was... interesting. I was keeping the screws in my transmission cases just barely tight to keep things nice and loose. Well, during practice, the car started to suddenly lose rear traction like crazy. I pulled it and realized all 6 screws in the rear case backed out. Oops

During the qualifiers and main things were better. I had one of the fastest qualifier paces until I screwed up, but the car is still very capable. I switched from Tamiya springs to Spec-R 2.6F and 2.5R, which was definitely better.

In the main, however, our traction was WAY up (CRC carpet, humid evening), and mid-main my handling became a handful. A ton of steering, rear end breaking loose, the car basically dancing around the front tires. Just not balanced at all. I went over it after the race and nothing looked broken, so I'm not sure what happened.

I now switched to Yokomo pink and blue springs, I'll try them out this week and see how it feels. I need to play more with droop, I think I had too much in the rear, which could explain the situation in the main (was running 6.6F and 6R on Hudy droop gauge and blocks). Gonna go up to 7F and 6.4R to start. Most of our track records were on Yoko springs, so might as well try those. HPI silver or blue could be another test.
Metalnut, what TC did you run before the EVO6? Have you done back to back comparisons yet where you were timing both cars?
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Old 09-28-2014, 05:17 PM   #791
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Metalnut, what TC did you run before the EVO6? Have you done back to back comparisons yet where you were timing both cars?
I'm coming from an Xray T4'13, but I haven't done back to back comparisons, no. This was only our second carpet race of the new season.
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Old 09-28-2014, 09:47 PM   #792
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Originally Posted by metalnut View Post
Second night with the EVO was... interesting. I was keeping the screws in my transmission cases just barely tight to keep things nice and loose. Well, during practice, the car started to suddenly lose rear traction like crazy. I pulled it and realized all 6 screws in the rear case backed out. Oops

During the qualifiers and main things were better. I had one of the fastest qualifier paces until I screwed up, but the car is still very capable. I switched from Tamiya springs to Spec-R 2.6F and 2.5R, which was definitely better.

In the main, however, our traction was WAY up (CRC carpet, humid evening), and mid-main my handling became a handful. A ton of steering, rear end breaking loose, the car basically dancing around the front tires. Just not balanced at all. I went over it after the race and nothing looked broken, so I'm not sure what happened.

I now switched to Yokomo pink and blue springs, I'll try them out this week and see how it feels. I need to play more with droop, I think I had too much in the rear, which could explain the situation in the main (was running 6.6F and 6R on Hudy droop gauge and blocks). Gonna go up to 7F and 6.4R to start. Most of our track records were on Yoko springs, so might as well try those. HPI silver or blue could be another test.
Wow that's not allot of droop at all. Is this what most are running with this car? I Always run way more like 5/4 4/4 or some times more.
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Old 09-28-2014, 10:47 PM   #793
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Wow that's not allot of droop at all. Is this what most are running with this car? I Always run way more like 5/4 4/4 or some times more.
Assuming I didn't screw up my droop measurements, 7F and 6.4R on a Hudy gauge gives about 2mm front and 3mm rear droop, which is still a lot for carpet. Last season I ran 1.5mm front and 2mm rear on my T4 on the same carpet/layout.
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Old 10-01-2014, 06:23 AM   #794
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Considering the Evo 6 for USGT. What do I need to purchase (part #'s) for the internal gears for this class?
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Old 10-01-2014, 07:01 AM   #795
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Considering the Evo 6 for USGT. What do I need to purchase (part #'s) for the internal gears for this class?
You won't have to upgrade anything for a 21.5t. I have been running my tb04 (same drivetrain as the evo6) for over 3 months now with a 21.5t and all the internal gears, ring and pinions and bevel gears have no signs of wear. My car is quieter than most belt drives that run 21.5t at the local track
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