Track Tac

Tires always seem to fall off early...

1fasttiller

1fasttiller

Member
Hi fellas, looking for some ideas again for my son. We moved to Jr3 this year and are now on a fresh '21 Slack Pursuit. Made our debut race this weekend at FDMS here in Florida for the New Years shootout. Once again I found my son starting out for the first 5 laps or so fast, and dramatically falls off as the race continues on. This was on a very high bite, calcium track. We ran the trophy race and the pro race and had the same thing occur both times. I had cured Maxxis (were fresh for the world 100 in November) Sets ranged in duro from 50-55-60. Most all were rolled with Track Tac's Kryptonite V2 at 75cc, 90cc rights and I had a set rolled with 75cc of Pink Magic as well. I also had an older very worn set that were fresh re-rolls done a week prior. All my tires were fast at the start of the race with my son turning lap times well within a few hundredths of the leaders (lap record is a 12.20 and he was turning 12.30's) But in the same token the leader was running a few 12.1's and consistent 12.20's late in the race where we fell of to 12.40s and 12.50's by the end.

What am I doing wrong! My theory is it is my inside prep game that is killing me. Our outside prep works well for the first several laps and he's fast then when its gone and the inside comes into play we slow down. Weirdest thing is this happens to us a lot even with using other inside preps and plagued us many times last year in Jr2 at big races.

Could it be kart setup? We basically went with Slacks out-of-the box setup and the kart seemed fast right out of the gate:

57.5% left
66% cross
53.6% rear

Camber at -2.5 and +.5

Any and all insight appreciated! He's a fairly experienced driver, very smooth and consistent for a 12 yr old. I'm sure he makes some mistakes but not a ton.
 
When the times start to fall off whats the kart doing? Is it getting loose/free, is it pushing the nose or sliding the RF. How big is the track? What do the tires look like after the race?
 
Dougherty#39 said:
When the times start to fall off whats the kart doing? Is it getting loose/free, is it pushing the nose or sliding the RF. How big is the track? What do the tires look like after the race?
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It seemed to go both ways for us Saturday, depending on the set of tires used. First set (harder tire) he said it started to get loose/free on exit as it got heat build, second feature and second set of tires that day (slightly softer since sun dropped and temps cooled down) he said it developed a push from center off. Definitely felt the RF sliding.

Track is fairly large, 1/5mile according to their site. Very fast track this race. Many track records were broken that day.

Tires were all showing slight graining after the features, very pronounced wear on the inside of the RF after the last feature.
 
Could go either way could be to soft, could be not enough prep, is the grainy look from to much grip or sliding in the million dollar question, since they were over 2 month old cured tires I'd lean toward your not prepped up enough, runs on prep 5 laps and gives up.
Another question were you turning high rpms again 6750 plus ? If so that's part of it as well if race stayed green flag mostly
 
No sir, after a chat with our new engine builder there he suggested we drop teeth and we did. Peak RPM was 6500-6600 all day, right where he wants it.
 
1fasttiller said:
No sir, after a chat with our new engine builder there he suggested we drop teeth and we did. Peak RPM was 6500-6600 all day, right where he wants it.
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I think your not prepped up enough and maybe wrong prep, if they were to soft and fell off in only 5 laps they would of ended up with bigger differences in lap times at the end. The grainy look is from sliding I think.
 
I really do think its either wrong prep or not enough internal. I just can't get a handle on it especially at this track!!

We're on Raging Bull Motors now, Definitely not lacking HP!
 
I'm thinkin not enough internal once the external wore off. I've been there lots of times and the kids yell at me lol.
Try dropping your cross a couple % also. The only time we're at 66-67 is on 1/4 mile tracks, found great speed at 63.5-64.
Both L blocks in front holes ?
 
1fasttiller said:
I really do think its either wrong prep or not enough internal. I just can't get a handle on it especially at this track!!

We're on Raging Bull Motors now, Definitely not lacking HP!
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I'd say not enough internal for sure, pretty sure not over prepped if it were by lap 5 by the end of the race it would of been all but undriveable with the hospital wobble, did you notice were the fast guys on fresh
Tires
 
Kj26 said:
I'm thinkin not enough internal once the external wore off. I've been there lots of times and the kids yell at me lol.
Try dropping your cross a couple % also. The only time we're at 66-67 is on 1/4 mile tracks, found great speed at 63.5-64.
Both L blocks in front holes ?
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I've been thinking that for awhile myself. I've crept up on amounts but still no luck it seems. This is a pretty big track and Slack recommended 65-66% cross in this new pursuit. I believe the LF L-block is in the front hole and RF is in the back hole (whatever PMI sets them to, we didn't touch)

Caster is at factory 10/12. I did have a well known guy there Saturday tell me we need to open the caster split up to 4* and run 7/11 to get it to unload the LR. I plan to try that in the coming weeks just to see how it reacts.
 
racing promotor said:
I'd say not enough internal for sure, pretty sure not over prepped if it were by lap 5 by the end of the race it would of been all but undriveable with the hospital wobble, did you notice were the fast guys on fresh
Tires
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Hard to tell for me really, most didn't seem to be "out of the wrapper" fresh though.
 
1fasttiller said:
I've been thinking that for awhile myself. I've crept up on amounts but still no luck it seems. This is a pretty big track and Slack recommended 65-66% cross in this new pursuit. I believe the LF L-block is in the front hole and RF is in the back hole (whatever PMI sets them to, we didn't touch)

Caster is at factory 10/12. I did have a well known guy there Saturday tell me we need to open the caster split up to 4* and run 7/11 to get it to unload the LR. I plan to try that in the coming weeks just to see how it reacts.
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For a 1/5th mile or bigger I'd get the RF in the front hole as Kj26 says, I'd also agree more caster split.
 
Thanks Gents, so you guys agree it could be some setup issues in addition to internal prep not being on point?

For hard, fast calcium tracks do I want to go more than 75cc internal? I was always taught not too. I know on the wet tracks down here we'll roll 100cc plus but thought you wanted to stay conservative on the fast tracks with lots of karts and a ton of bite.
 
1fasttiller said:
Thanks Gents, so you guys agree it could be some setup issues in addition to internal prep not being on point?

For hard, fast calcium tracks do I want to go more than 75cc internal? I was always taught not too. I know on the wet tracks down here we'll roll 100cc plus but thought you wanted to stay conservative on the fast tracks with lots of karts and a ton of bite.
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90 % of the issue I'd say was prep, were suggesting set up adjustment so if on right tire you will be the 12.1, your just not using enough Internal even for fast Calcium 75 cc is not enough for Jr 3 90 cc to 100 cc, wet tracks more slick 120 cc to 140 cc, you will stay more conservative on faster gripped up track, your just being over conservative especially for a cured tire.
 
1fasttiller said:
I've been thinking that for awhile myself. I've crept up on amounts but still no luck it seems. This is a pretty big track and Slack recommended 65-66% cross in this new pursuit. I believe the LF L-block is in the front hole and RF is in the back hole (whatever PMI sets them to, we didn't touch)

Caster is at factory 10/12. I did have a well known guy there Saturday tell me we need to open the caster split up to 4* and run 7/11 to get it to unload the LR. I plan to try that in the coming weeks just to see how it reacts.
Click to expand...
I don’t care what they recommend lol, you need to try stuff for yourself, especially being down there where there’s not a lot of Slacks. My daughter has been very successful on her 19’ Pursuit & my son is switching to one this yr. Open up the caster, add more RF camber, heck reduce LF camber, once you find that front end sweet spot your golden. Oh ya add more internal, you wouldn’t believe me if I told ya what I did to my Vegas in 95 degree weather haha.
 
Just a thought here . I would say the above posts are correct . Tire fast early would be outside prep , tire fast late would be inside prep .
The original statment -tires fall off early . Two or more sets act the same .
All appear prepped similar .
We had a similar issue . Driver/tire guy prepped the tires .
I said they all seem the same . Driver disagreed .
 
Kj26 said:
I don’t care what they recommend lol, you need to try stuff for yourself, especially being down there where there’s not a lot of Slacks. My daughter has been very successful on her 19’ Pursuit & my son is switching to one this yr. Open up the caster, add more RF camber, heck reduce LF camber, once you find that front end sweet spot your golden. Oh ya add more internal, you wouldn’t believe me if I told ya what I did to my Vegas in 95 degree weather haha.
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Understood! The guy that owns the kart is a little tough to persuade but I've got him talked into changing caster to 7/11 and I also think I'm going to lower the cross a bit before the next time out.
 
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