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Discussion Starter · #1 ·
Hi All,

After last night's blistering pace at the WHO Mod round, I've already started thinking about April's round two and what I can do to squeeze even more performance out of my cars and hopefully try to cling onto Dr. Who's coat tails.

And after the usual processes of lowering the front with ground down tyres, changing the gearing, upgrading the traction magnets and running silicones my thoughts have turned to this:

Is there a performance advantage to be gained from running a larger hub with a lower profile tyre over a smaller hub with a larger diameter tyre?

I have noticed quite a few of the Pro-Mod cars at EAHORC plus a couple of very well prepared Mod cars at WHO and EAHORC all seem to have very skinny rear tyres but proportionally larger hub sizes to what I have been using. This leads me to suspect that, similar to real life, there is a disadvantage in having all of that flexible silicone moving around on the hub and pushing to the outside during cornering and that a lower profile tyre would be beneficial.

Has anyone done any experiments with this and what did they notice? I'm going to post this one on the US forums as well and see what wisdom they can share.

Cheers

Gareth
 

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Hi Gareth---you know well that I am not up to scratch with technical bits but I can give you one piece of advice----make sure I am nowhere near the track when you race!!!!!! You may stay on then!!!!
 

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Discussion Starter · #3 ·
QUOTE (pne4ever @ 12 Jan 2012, 13:09) <{POST_SNAPBACK}>Hi Gareth---you know well that I am not up to scratch with technical bits but I can give you one piece of advice----make sure I am nowhere near the track when you race!!!!!! You may stay on then!!!!

I'll give you a cigarette for when I do my heats!


And you can take Rick with you as well after last night!

I don't mind too much if I get knocked off by a marshalling slip up. These things do happen and it isn't like people try to do it!! As long as people marshalling try their best and pay attention to the cars incoming all is good.
 

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QUOTE (Gareth @ 12 Jan 2012, 12:32) <{POST_SNAPBACK}>Is there a performance advantage to be gained from running a larger hub with a lower profile tyre over a smaller hub with a larger diameter tyre?
If running strong traction magnets, yes.

The stronger the traction mags, the more pressure on the tyres - and if they squash, you run the risk of the car bottoming-out, the arm heating up and the car slowing down. That's all bad news, plus the car components will wear out quicker.

In that case, larger hubs and thin tyres are better than just bigger tyres. A good idea is also to go for the hard 'B' compound Supertires (in the club shop) or use stock rubber tyres - the SCD SRTs run well on these.
 

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Once you get into the really fast stuff rigidity starts to really pay off, this is why you will start to see more stiff G3 chassis nationally, .300 wheels and low profile tyres.

The same applies to the WHO class.

Is the G3 chassis allowed?
 

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Discussion Starter · #6 ·
Thanks for the replies chaps. Useful stuff. I did have a couple of good replies on SCI as well and the .300 seems to be a good wheel to look at.

The G3 is allowed yes. I think I'm already using one in my Nascar so I may swap it over to the Mod car instead.
 

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QUOTE (montoya1 @ 12 Jan 2012, 17:17) <{POST_SNAPBACK}>The whole car, or the chassis with SG+ part in?

Just the G3 chassis and traction magnets are legal but all the other parts need to be Super G.

Reasons:

The G3 chassis is ment to to be a direct replacement for the flawed black SG chassis. The grey SG chassis is only available as part of a complete car to the best of my knowledge. Plus SG's are no longer being made.

The BSRT traction magnets are allowed its an open traction magnet class. Even if you used a standard SG chassis you can use LB neo's or HC tractions magnets which are comparable in strength.
 

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I'd recommend a stiff G3 with the LB Neos and .290 or .300 wheels, and SPG guts if nobody has tried that already. If there are cars at WHO that are quicker than that then somebody should try them at national Pro-Mod level.
 

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Discussion Starter · #10 ·
Your comment intrigued me Deane so based upon knowing the average lane length of 60 feet, 12 inches per foot and the last fastest lap that I heard called from my final (which was for me) which was 2.8 seconds I know that I achieved an average lap speed during that lap of 257 ips which is quick but not really quick enough for Pro-Mod territory although it isn't a million miles away.

And I also know that I was running tyres a lot lower than I was in my earlier heats and I was starting to feel it bogging down, struggling and not running freely. So presumably that is the optimum size tyre once I switch to big rims and low profiles. I am also upgrading the gearing again so I'll be interested to see how much closer to that magical 300 ips figure I can get.

Just done some more calculations based on the performance in the finals.

John managed 60.5 laps in 3 minutes which is an average speed for the whole race of 242 ips whereas my (rather more pitiful) score of 48.8 is only good enough for 195 ips.

If Andy can supply us with the fastest lap of the A Final which I think he knows then he can also calculate the average speed of that lap and tell us how near his Mega G was to Pro Mod pace!

Please let me know if I've done these calculations wrong.
 

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Andy Player
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Sorry, no fastest lap times from Wednesday - it was all a bit too hectic at the end


With Trackmate we can do stuff like that easier. Hopefully February or March...

But I think we are getting into tail-ender Pro-Mod territory.

Personally, I think the successful road to understanding this is to change one thing at a time. You might get the tyres right but the gearing wrong, but if you did both, you'd be none the wiser. Development at this end of the speed spectrum is a patient process, but one worth doing right.
 

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FYI we run the Slottechs on .275's

Going to be trying Super Tire B's Instead of slottechs for the first time in sunday on spanking new WHP hubs. As Andy says change one thing at a time, last month the arm and it was too damn fast.

I'm convinced a marchon with a better arm and a lexan has pro mod potential as maybe would a heavily modded mega g. Someone using a hobby chassis should always be able to do a better job, but their complexity means we rarely all do a good job on the same day.
 

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Discussion Starter · #13 ·
Shame there were no laptimes from the A Final. It was so quick that it would have been interesting to know. Track Mate is going to be great.

Good tip on not doing everything at once. I'll add the hubs and low profiles and then look at gearing again.

Lucky Bob only has the coloured Quicker hubs so green for .300. Any other stockists?
 

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QUOTE (marctownsend @ 13 Jan 2012, 12:28) <{POST_SNAPBACK}>I'm convinced a marchon with a better arm and a lexan has pro mod potential as maybe would a heavily modded mega g. Someone using a hobby chassis should always be able to do a better job, but their complexity means we rarely all do a good job on the same day.

As I have been running the MR1 for many years I have also looked into that possibility, but came to the conclusion as good a chassis as that is, the traction mags would not quite be up to it and there are no hop-ups for the mags that I know of, for a 20 or so, year old chassis. Yes it may be very good, but would be a monster to control with a hot motor, even with the mags nearly dragging the track!

Now where did I put those big gold Neo's, I might resurect the project yet!
 

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QUOTE (Gareth @ 13 Jan 2012, 12:52) <{POST_SNAPBACK}>Lucky Bob only has the coloured Quicker hubs so green for .300. Any other stockists?

BSRT do .300" rims. But I reckon the Quicker hubs are more versatile and the colours a good reminder of what OD you're running


I'd try .275", .290" and .300" rims with .418" or .422" Tyco 'B' compound Supertires. See what works. Going too high is also a disaster at those speeds...

You could compare distance travelled in 3 minutes at EAHORC pro-mod and WHO Mod. Our track lengths are approximate, but I do have a gizmo that AndySlots built that I could use quickly at the beginning or before we break up the track.

John's MR-1 is very quick with the lexan shell, but I suspect Martin has got that car within a micron of it's ultimate potential. I think the Life Likes and Tycos will go faster. I might even do it with the Mega-G
 

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Discussion Starter · #17 ·
QUOTE (woodcote @ 13 Jan 2012, 13:16) <{POST_SNAPBACK}>BSRT do .300" rims. But I reckon the Quicker hubs are more versatile and the colours a good reminder of what OD you're running


I'd try .275", .290" and .300" rims with .418" or .422" Tyco 'B' compound Supertires. See what works. Going too high is also a disaster at those speeds...

You could compare distance travelled in 3 minutes at EAHORC pro-mod and WHO Mod. Our track lengths are approximate, but I do have a gizmo that AndySlots built that I could use quickly at the beginning or before we break up the track.

John's MR-1 is very quick with the lexan shell, but I suspect Martin has got that car within a micron of it's ultimate potential. I think the Life Likes and Tycos will go faster. I might even do it with the Mega-G

Looks like I'll be breaking out the garish coloured hubs then!


I agree on John's MR-1. If Martin churns out a further update this season then we are all truly screwed!! Although fairplay, it is an amazing car.


But I also agree that there is plenty more potential in the other chassis. So many goodies to buy what with spacers, gear bosses and all sorts of other gizmos too. I am contemplating being incredibly decadent and keeping the current car as is and building up a different car so I always have a benchmark to compare it to.

And I'm going to try and do it still using my trusty Parma Eco as well!
 

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QUOTE (montoya1 @ 13 Jan 2012, 13:34) <{POST_SNAPBACK}>BSRT will be discontinuing a lot of their wheels and tyres, as they unleash a new tyre which is molded in some super-duper way and is a 'must have'. I remain unconvinced, just as I always am when they keep bringing out new magnets.

Is BSRTs tire/hub "discontinuing" common knowledge or something you found out from a USA insider? Just curious as it would be a shame for the 5 star/spoke wheels to be discontinued as they look so good.
 

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Discussion Starter · #19 ·
QUOTE (woodcote @ 7 Apr 2011, 07:58) <{POST_SNAPBACK}>A quick stat: Robin's A final run works out at 226.4 inches per second over 3 minutes. That is comfortably beyond EAHORC Mod pace and beats some of the pro-mod's fastest laps of the day at Marlborough.

After Andy posted links to the April Mod round from last year and to the Mod round just gone I was interested to spot this stat. The fastest car of the A Final in January 2012 being 16 ips faster or a 1.3 feet a second quicker than April 11.

And I know the track wasn't exactly the same as the layout posted on the Jan thread but they were very similar. The diagrams are identical though!


Be good to keep an eye on what is achievable come April 13. 300 ips perhaps?
 
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