106 replies to this topic

[Mike Patterson]

I'm going to build an F1 chassis in the near future, and I am looking for design input. What type of pan hinge seems to work the best, plumber, shaker or floppy? Narrow center section or wide (1")? I'm not looking to build anything super trick, just a good handling basic chassis that is within my constuction skills.

I realize there are probably several examples on the chassis building forum, but with a dial-up ISP, that's pretty much off limits !

I would appreciate any and all suggestions.

[gascarnut]

Mike,

4" wheelbase, 1" guide lead from the front axle.

3/4" wide JK bracket, then three rails each side, one of .062" steel, 2 of .062" brass or low-fuming bronze brazing rod.

The nose piece - .062 thick by 1" to 1.25" long, then another loose shaker plate behind it that's about 1.5" long.

Side plates - .062 thick by 1/4" wide and 5" long so they go from the front of the nosepiece all the way to the back of the motor bracket. Connect the side plates to the center shaker plate with your pin tubes, then use some little wire saddles like the pan stops on a CanAm frame to hold the whole lot in place and let it "rattle about .010 to .015 up and down and about .030" or so fore and aft.

Ask Jay Kisling how this one works.......

[Pappy]

Dennis,

Do you solder the three side rails together all the way from front to back or just on the ends?

[Tigwldr]

Do you have pics of one of these designs?

[Noose]

Here are some pics of the chassis that Dennis is talking about. It's Jay Kisling's from this past weekend and at the R4.







This one is mine which works just as well. The top pic of mine though is without the center pan as I took it out a particular race where on an old style King it turned the fastest laps during the race eclipsing the TQ time. The bottom one is with the pan as it was at the R4

[tonyp]

Dennis's design is a good bet for all all around great handling F1 chassis which will work on just about any track. You can not go wrong at all.

[gascarnut]

Dennis,

Do you solder the three side rails together all the way from front to back or just on the ends?

I try to keep them as separate as possible, so they are all soldered together at the rear and the front, and then where the stops are the two inner rails are soldered together.

You have to be careful soldering long lengths of brass to long lengths of steel, as they expand at sifferent rates and it is difficult to keep the rails straight. small amounts of heat at a time, and short lengths of solder joint are needed.

Do you have pics of one of these designs?

Sure, this is the one that Jack Beers used at the R4/2 (he won it at the Sano 2):





This is Steve Brown's frame, the pan attachments are a bit different:





I see Noose snuck in some shots too, while i was writing this.

[Pappy]

Dennis,

Have you tried this same design with a little longer wheelbase?

[gascarnut]

No - with a 5" guide lead from the rear axle it is already quite long, and I don't know if anything longer will fit under the bodies properly.

There's nothing stopping you trying, though. A longer version might be nice on a flat track.

My D3 design runs well on the BPR flat track, and it is the same length:





Disclaimer: Remember that the front end design of this car is not IRRA-legal.

This car was modified slightly after the photos were taken, to add more weight at the rear. There is now a piece of .062 brass filling the inside of the bracket, and another strip of .062 x 1/4" wide connecting the two pans across the back behind the bracket. The steel rails are also on the outside in this design, as opposed to being on the inside in the IRRA frames. On this particular car, I used .055 steel and .062 bronze for a slightly more flexible frame. The owner is very happy with it so far.

[Mike Patterson]

Dennis, thank you for sharing. I have a couple of questions: The wire that connects the pans in back is not soldered to anything but the pans, correct? And why the brass rod? I would think this would tend to make the chassis more flexible, am I correct in this assumption?

[gascarnut]

Mike,

The wire across the back joins the two side pans and rests on top of the motor bracket brace so the pans don't droop. It is not attached to anything except the pans. On some of my frames I have a little "up-stop" back there as well to limit the upward travel of the pans, but mostly I just let them move up as far as they want to go naturally.

The combination of brass and steel makes for not only a more flexible frame, but for more "dampened" flex. The frames react a little slower than the equivalent flexibility in an all-steel frame would do, so they feel more forgiving.

Plus, they look cool.......

I'm glad you find all this helpful, steal as many ideas as you like, add some of your own and let's see the photos when you're done.

[TSR]

That's a pretty car. Love the front end...

[Dooner]

Dennis,
I have never seen anything you have built that I did not like. I really like the clean lines of this chassis. And I have to agree with Philippe; that front end is too cool. It looks as though the car has a lower control arm.

[Mike Patterson]

Dennis,

I'll post some pictures when I have some. Right now I have to scrounge up a couple of narrow motor brackets. I like to draw a plan view of the chassis I'm building, usually to use for patterns, as well as to check measurements, and I need the brackets to start. Give me a couple of weeks.

Have you ever built one of these chassis where the center weight is NOT connected to the pans?

[Pappy]

Mike,

Rick has a new narrow motor bracket that I like.

[gascarnut]

Have you ever built one of these chassis where the center weight is NOT connected to the pans?

No, but I know that others have. Mike Steube had a few like that where the center pan was suspended from the front axle by a piece of .047 wire. He called it a "Mass damper" and I think it worked pretty well. It's difficult to say what works with Steube's stuff 'cos he's such a good driver, everything he builds looks "jet".

I should try that on my next one.

[Mike K]

No, but I know that others have. Mike Steube had a few like that where the center pan was suspended from the front axle by a piece of .047 wire. He called it a "Mass damper" and I think it worked pretty well. It's difficult to say what works with Steube's stuff 'cos he's such a good driver, everything he builds looks "jet".

I should try that on my next one.

The Steube F1 I have has the body mounted off of a wire from the front axle, as you describe. A true floating mount!

[Tigwldr]

Mike,

4" wheelbase, 1" guide lead from the front axle.

3/4" wide JK bracket, then three rails each side, one of .062" steel, 2 of .062" brass or low-fuming bronze brazing rod.

The nose piece - .062 thick by 1" to 1.25" long, then another loose shaker plate behind it that's about 1.5" long.

Side plates - .062 thick by 1/4" wide and 5" long so they go from the front of the nosepiece all the way to the back of the motor bracket. Connect the side plates to the center shaker plate with your pin tubes, then use some little wire saddles like the pan stops on a CanAm frame to hold the whole lot in place and let it "rattle about .010 to .015 up and down and about .030" or so fore and aft.

Ask Jay Kisling how this one works.......

How are you using the 1" wide nose plate with a 3/4" motor box? Are you shimming the sides of the motor box or something to make it the same width as the nose pc when you run the rails from front to back?

[MSwiss]

How are you using the 1" wide nose plate with a 3/4" motor box? Are you shimming the sides of the motor box or something to make it the same width as the nose pc when you run the rails from front to back?

I think .062 thick by 1" to 1.25" long threw you off a bit.
It's not 1" x 1.25".

Dennis can confirm but I'm 99.9% sure the plate in the pic is 3/4" wide.

[Tigwldr]

I think .062 thick by 1" to 1.25" long threw you off a bit.
It's not 1" x 1.25".

Dennis can confirm but I'm 99.9% sure the plate in the pic is 3/4" wide.

I think that answered my question. I need to trim 1/4 off of it. Thanks for the help.

[Mike Patterson]

All of the necessary pieces/parts have been acquired, except for a body (I'm still working on that). There's a good chance construction will begin this weekend.

Dennis, on your front end setups, I've noticed that on some the middle brass mainrail bends up to support the back of the front axle. Is the front "L" shaped piece steel? On Jay Kisling's car, it appears to only have 1 (one) front axle support per side. True? Any particular reason for rhe variance, or just experimentation?

Thanks!

[gascarnut]

Mike,

All the IRRA frames use two steel axle mounts on each side. THe middle brass rail stops short of the axle mount. Take a close look at this one, and you can see the joint:



I don't think that the brass rails would be stiff enough for an axle mounting.

To answer Tigwldr's question, the nose pieces are always 3/4" wide, it's the length that varies from 1" to 1.25". The center pan also starts out at 3/4" wide, but I usually file about 1/32" off the width so there's a bit of side to side movement between the rails.

[Mike Patterson]

Dennis,

Thank you for clearing that up. I can see the joint now that you pointed it out!

Hopefully I'll have some pictures here in a couple of days.

[Mike Patterson]

Well, it's been four days instead of two, and here's what I have so far:



I stiil have to add the pans and "inertial dampener", and trim various things to length. Also size, machine and install the pans. THAT ought to be fun!

More to come.

[gascarnut]

Looking good!

Nice strong construction around where the axle tubes go through the bracket.

When you cut the center pan, make it about .020" to .030" narrower than the space between the rails.

Then when you solder the pin tubes across to hold the center pan to the side pans, space everything over one way, solder one pan, then the other way to solder the other pan, so you have some side-to-side play in the whole assembly once you're done.