51 replies to this topic

[James Grandi]

Hey all, food for thought topic here.

 

Only built two F1 chassis so far, and raced my most recent build at Hudson Valley Raceway this past weekend with Retro East.

 

The car ran well and I didn't have any problems with it popping out (other than driver error), but I noticed that coming out of the bank it would seem to almost break loose, twitch back and forth before straightening back out. It didn't cause any problems other than breaking momentum, and it wasn't something I noticed much in other cars.

 

This sound familiar to anyone? If so, are there some specific causes to look for?

[MSwiss]

What type of tires did you run?

[Half Fast]

Most people run pretty soft tires at HVR (i.e. untreated) which seems to prevent this.

 

Cheers,

[James Grandi]

Mike, I ran Kelly Retro. I believe five other cars in that main also ran Retros, though I didn't observe the same behavior from their cars.

[MSwiss]

You might be running a slightly stiffer chassis.

Also, if you haven't already, carefully check the adhesion of the rubber on the rim.

On a long shot, it might be a tiny spot where it's peeling, just enough to only show up at high speeds.

[James Grandi]

This is true, it isn't a car built with a lot of movement in mind. Eight rails of .047" soldered all the way, Z-rail pan setup with .047" into 3/32" square for up/down stops.

 

I didn't think to check the rubber for how well it was glued, I will once I'm at my workbench again.

 

Thanks!

[MSwiss]

Is the car that Eric has been doing well with, full soldered?

At our IRRL races on the Gerding King, at M/A, F1's twitching coming out of the bank, was fairly common, especially in practice and the early Mains.

Also on my King right after cleaning if I sprayed it on the light side.

[James Grandi]

Eric's is full soldered, using a shaker pan setup instead of Z-rail pans.

[Rick]

Most King tracks lay the bank exit over too quickly for non-air cars; it doesn't show with air cars.

 

Probably your tires were too hard for this track and as rubber builds up this will go away. A too loose floppy guide can also do this or contribute to it...

[W. J. Dougherty]

Also check your chassis clearance as it exits the bank and transitions to the chute. It may be bottoming out... Your clearance may be good on the straight but if it is off on the exit of the bank you may have some problems. We have had that issue...

[Cap Henry]

What body? Did you try adding some lead to the back of the pans? If you can put lead on the center weight to just increase total weight without a major effect on balance.

 

It may be the difference in pan set-ups. Some F1s twitch out of the bank on my King, and a car with the Z-rail style pans did and a car the same other then having shaker pans didn't. 

[JerseyJohn]

Tires too loose, pal. My car was swinging out of the bank as well as several others. Untreated rubber cured the problem.

 

The greatest chassis in the world doesn't do squat unless your tires have the correct bite.

 

JJ

[MSwiss]

He finished fifth out of 30 guys.

His tire selection couldn't have been that far off. LOL.

[Cap Henry]

First and third ran Retros, second ran JK naturals.

All three had shaker pans though.

[James Grandi]

Cap,

 

I ran an O/S M7. Added 5 grams of lead to the center weight, 3 on the pans toward the rear of the chassis, total weight was 112.4. I'll have to build a chassis with a shaker pan setup and test it out

I tried JK treated and untreated in practice, but it killed my momentum running up the donut so I had to switch to Retros. The car wasn't slow or bad handling by any means; it was a good race. Retro racing is so tight that those little quirks that break momentum can end up making a difference at the end, one of the reasons I like this style of racing so much

[MSwiss]

And also Eric in fourth.

But on my phone, I can't quite figure out for sure how Edsel's pans move.

[Noose]

Spoke to Edsel.

 

The dimensions on his car are: 3-15/16" wheelbase and 31/32" guide lead. Side pans .062". The front, middle, and rear pieces are .045". He said there is not a lot of movement side to side or front to back but the rear list is .015".

 

This thing was on rails the whole race. He ran 4.7s on every lane.

 

Here are bigger pics of this car.

 

 

[MSwiss]

Great pic. Thanks.

As Johnny Nash says, "I can see clearly now."

It looks like he just relies on "S" stops in the front to keep the thing together... and one peeled off (edit) and a miniscule "L".

Probably his secret to success. LOL.

[Tex]

Very interesting...

[Rick]

When did they start drilling the balance holes instead of the grind slash?...

[Noose]

That is a slash, Rick. It goes backwards toward the end of the stack. I had some like that from the old batch and new batch.

[Half Fast]

Thanks, Noose and Ed. It's good to get a good close-up of top cars!

 

Cheers,

[Noose]

Ed thanks K&S of course. LOL.

 

He used a JK bracket, too.

[Half Fast]

 He used a JK bracket, too.

 

One shot and it folds up like a cheap suitcase! Good thing Ed is always in the A Main. 

 

Cheers,

[James Grandi]

Noose, thanks for the great pictures of Ed's car. He was definitely on rails the whole race, blew me away how bad-fast he was down in black, too. Think he cracked off some 4.6s down there.

His car is a bit shorter overall, I built mine at a simple 4" wheelbase, 1" guide lead. I like how he split the main rails; it's got a very unique look.

One thing I've yet to try using on any of my chassis is that dampening tape.