17 replies to this topic

[John Good]

Not sure where to post this.  After about a thousand laps of practice Sunday (and attempts at tuning), I'm left with a handling issue.  My Retro F1, which weighs 114 grams, wobbles side to side at the rear under hard braking.  Only happens at the end of the straight following the Bend.  Adding weight on the center pan didn't help.  Neither did adding spacers to guide.  any thoughts/advice????

[Dominator]

Try double checking the guide spacing on the track in 3-4 spots with the body off. When you push down on the guide the front wheels should touch without the rear tires lifting or lifting very little.

Also check to make sure your front tires are round and the same size. F1 fronts can take a beating so be sure to check the rims also.

Check to make sure the chassis is flat and that the front and rear axles are set at the proper ride height.

If after you have checked this it may simply be time to replace the main rails on the chassis. This is something that has to be done every so often especially with thinner gauge wire like .047 as after time if develops memory.

[TG Racing]

John,  Dom has some good ideas.  I think I woud try sodering a rail on top of the other rail first.

[slotcarone]

Sounds like there is nothing wrong with the car--you need to back off on the brakes!!  Coming out of the bank into the deadman the track is still crooked so it is exaggerated there.

[John Streisguth]

On one king track my F1 was doing the same thing, but when I changed to a wheel that the hub wasn't full width, it stopped.  Try a tire with a smaller hub.

 

And as Dom mentioned, check the car on a flat block to make sure the chassis isn't "tweaked".

[James Grandi]

Well all these guys pretty much covered the lot of it. Only thing I would add, check your rear bearings. Make sure they spin nice and free. If you've got one that is starting to give up the ghost, it can play havoc with the attitude of the car under braking/corner entry

[tonyp]

All good replies.


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[John Streisguth]

Two other things that came to mind:

 

-Check to make sure the wheelbase is the same on both sides. F1s, with the exposed front wheels, are prone to getting the front axles bent from a crash.  It may not be noticeable by eye, but a caliper will show. Also use straight edge to check the axle itself.

 

-You don't say who built the chassis, but sometimes beginners try to "force" rails to lay flat (I'm guilty of that myself).  If you do that, that chassis will always have a "spring" to it.  Regardless of that, you can also try putting the chassis on a jig and heating it up a section at a time.  There may be stress in the chassis that this will relax.

[Noose]

Seeing from where you are leads me to believe you are running RETRO rules perhaps and using the PS 4002FK motor. Those have a tremendous amount of brakes as soon as you let off even a bit which as Mike Katz noted can be the problem.

[brnursebmt]

Coned tires can make a F1 act real funny under brakes.  Or any car for that matter.

[Dallas Jackson]

Bobby hit right on the head.  I'll  say this. Do not use plastic rims;;;baaaad

[JerseyJohn]

Not sure where to post this.  After about a thousand laps of practice Sunday (and attempts at tuning), I'm left with a handling issue.  My Retro F1, which weighs 114 grams, wobbles side to side at the rear under hard braking.  Only happens at the end of the straight following the Bend.  Adding weight on the center pan didn't help.  Neither did adding spacers to guide.  any thoughts/advice????

 Setting proper guide height.pdf   251.58KB   156 downloads

[JerseyJohn]

Setting proper guide height.pdf

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[John Good]

Thank you all for the advice.  I stripped the car down and found a loose bearing in the motor bracket.  Re-soldered that.  Also, put it on a block and it seemed flat.  Checked the squareness of the axles to the chassis by measuring the distance between them with a micrometer on both sides, and they were within a thousandth.  I'll check the guide height at the track this weekend.

[willy wonka]

Bobby hit right on the head.  I'll  say this. Do not use plastic rims;;;baaaad

I strictly use plastic rims with no problems.

[willy wonka]

If your using the psfk proslot motor odds are your using to much breaks..

[Radical Racing]

Make sure your rear axles bushings/bearing are the exact same height.    I am not finished filing the holes and soldering in my rear axles bushings/bearing until they are within 1/1000 of each other when measured with calipers.    We discovered this the hard way with the original Champion Turbo Flex chassis wobbling side to side under braking many years ago.   Champion's stamping die and QC were bad at first and the rear axle holes were off by 15 - 25 thousandths.  

[Bill from NH]

Butch Dunaway once made Jiggy & Magna Jiggy jigs. Either of these jigs made it easy to set equal axle heights  & be sure the axle is perpendicular to chassis center line on stamped chassis. Unfortunately, these jigs are not still available, but how-to build a Magna Jiggy instructions are still loaded on OWH.