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Retro F1 front clearance question


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#1 John Good

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Posted 23 June 2017 - 09:21 AM

How important is it to be at or near the IRRA minimum front clearance on a Retro F1?  How high is too high?  All thoughts appreciated.






#2 Upfront slot cars

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Posted 23 June 2017 - 10:25 AM

Lower COG is always better.
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#3 Tex

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Posted 23 June 2017 - 10:26 AM

lowest possible CoG is always to be strived for in any form of car racing. of course, we don't realistically have a way to measure the difference in overall adhesion(other than a driver's "feel") between two identically scratchbuilt slot cars(an impossibility) with the only difference being a few thou of clearance. bear in mind that any difference in front clearance affects overall clearance of the car all the way back to the rear axle and beyond(gear guard). a difference in front clearance is just one of the many little factors that can add up to the overall performance of the car; the more of those little details you pay attention to, the better off you'll be.


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#4 Dominator

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Posted 23 June 2017 - 11:09 AM

Switching from a .750 to .760 front tire will also require the guide to be adjusted.
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#5 JerseyJohn

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Posted 23 June 2017 - 11:13 AM

 some help in setting guide hight.

 

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#6 Ramcatlarry

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Posted 23 June 2017 - 12:01 PM

It IS checked in tech.


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#7 Mike Patterson

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Posted 23 June 2017 - 08:33 PM

I build my chassis with 0.032+", so as not to damage Tom Thumb's bank any more than it is.


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#8 James Grandi

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Posted 23 June 2017 - 08:37 PM

You want it as low as you can get. If passing tech is a real concern, aka you don't feel confident about using a .015 gauge to set the clearance, use a .016 gauge - but no more than that


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#9 Richard G With

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Posted 24 June 2017 - 04:06 PM

I use jig wheels but usually wind up finishing the axle installation with the chassis sitting on the wheels,

no guide and a piece of .015 wire under the "farthest forward" point of the frame. I usually use hard JK fronts which tend to be

around .760 so this method will get the clearance with the actual tires. If you go with the jig wheel result you will

be a little high.

 

Yes, I have access to a tire truer but figure by the time my fronts have worn enough to be too low the tires will still be legal diameter

and I can use the same method to reset the ride height assuming the chassis is still usable.

 

.015" is not much clearance, it took me a few builds to believe my ride height was right!


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#10 Ramcatlarry

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Posted 25 June 2017 - 10:57 AM

Jig wheels CAN get you in trouble if the fronts you intend to use are not the right size to match the jigs.  Allow an option to confirm chassis clearance with the tires installed....they DO wear over time, as well.


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#11 JerseyJohn

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Posted 25 June 2017 - 01:23 PM

ok IRRA front clearance spec is .015. with a min tire diameter of .750 . Jk Fronts average about .765-.770 HVR BB front are .775-.780 so right off the bat using these wheels un cut is goin to raise the front an additional .010- .015 almost double the min clearance.

You can do several thing to get it right.

 

A. BEST WAY Cut the tires to .752 and use your standard jig wheel

 

B.  GOOD WAY Dont cut the tires so add .010 on jk or .015 on HVR under the jig wheels. Average business card is around .010 . keep putting the same UNcut tires on and all is well.

 

C.  CLOSE ENOUGH WAY Use standard jig wheels , mount all 4 tires . put .015 gauge under front and adjust axle height by un soldering and adjusting chassis down to set clearance. 

 

Also remember rear wheels higher than .812 will pitch nose down. lower than .812 will raise nose.

 

So if your running .790 rears on your F1 You might want to check the nose clearance. And use step C. to adjust. 

 

Regards JJ


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#12 John Good

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Posted 29 June 2017 - 12:13 PM

Thanks to everyone for their thoughts.







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