Alignment of Pinecar Single-Axle

[garthbro]

We are preparing for a Pinecar race, but I've found very little suggestions on how to address alignment of the single-piece axle. When I roll the axles on a flat surface, there is little "chatter", so they seem fairly straight. Also, the axle slots are already cut in our wood block.

Regardless of how much adjustment we make, are there any suggestions for shimming the axle? I'm guessing just a combination of rotating the axle and using wax paper or filing the slot.

On a basic level, I would think the focus should be on trying to get a straight alignment out of the car.

Beyond that, I was thinking of the following:

- Try to align the rear wheels per the methods documented in the forum
- Angle and shim the front axle to try to create a 3-wheel, rail rider
- Offset the front axle to the DFW is closer to the body (shave 1/16" off body on this side) to try to prevent rear wheels from rubbing against center track guide?

The obvious difficulty is the loss of flexibility in having 4 independent axles to adjust. Seems like adjustments will be much more difficult to accomplish with the single-axle.

I appreciate any thoughts, suggestions or experiences.

 

[Kinser Racing]

I've never ran pinecar before. Maybe somebody with that experience will chime in. Don't they also have the kits without the solid axle? Maybe you could start out with on of those. /images/boards/smilies/smile.gif

 

[IAE Racing]

So here is what I do. First, relax your axle slot by scratching the bottom and sides slightly and evenly, Front and back.
For the front: to make just a three wheeler, I use my coping saw to scratch a little more wood from one side. Be sure to push your axle through from the side. A lot of people make the mistake of trying to push in from the bottom.

To make a rail runner, make a slght relief cut same as bending a scout axle. to bend my axles I lay over an old block with some curve. I center the cut over the dip in a curve and push down with a heavy straight screwdriver. I shoot for s 5 deg bend. (The bending is basicly the same as doing a scout axle. As you can see in the pic, I used my router bit mount in drill press and made a slot for tuning with needle nose pliers. For the lifted wheel, I took a small dab of cotton and made a tread. threaded it through the lifted wheel then put wheel on axle. This keeps the wheel from vibrating.

For the rear wheels, make sure axles are the same distance from the bottom of the car and square. All other rules apply. The "right way" to cant the rears would be cut the axle in half and drill holes. We had an issue with one car this year and split out the wood around the slot (I should have relived the slot before I cut the weight pockets (like we preach on a BSA build) and slightly bent the axle, instead of straightnig the axle I bent it in the middle and we glued it (less desirable ((hard to get right)) and wasn't the fastest we built)

The car in the pic has too much steer, left it so it was easier to see.

 

[garthbro]

Appreciate the quick feedback...

I've seen the advice to cut the solid axles. Unfortunately, the rules state that the axles cannot be modified. I'm going to polish the axles where the wheel hub will run, but I'm expecting that's all I'll be able to do.

Definitely clear on making a three wheeler...it's in line with what I was planning.

Sounds like the most challenging part will be bending the solid axle for a rail rider. I'm guessing the 5-degree bend you suggest is so that I've got flexibility to adjust +/- 5 degrees from "straight"? It appears that most feel that a 1.5 to 2.5 degree DFW angle is optimal for rail riding - just enough to keep it on the rail.

Would it be worthwhile to create a three wheeler even if I don't bend the axle for rail riding? I may avoid axle bending...at least this time around!

 

[IAE Racing]

If you cannot "modify" axles, is bending for RR allowed? When you say "three wheeler" do you mean one lifted, or only three wheels? Either way, I'd only put three down. I don't have any experience with an actual 3 wheel car that wasnt't RR. We did build two actual three wheel cars this year. We cut the front axle so we could put a 90 deg bend on the no wheel side. We ended up having to put the fourth wheel on even though the rules didn't state you had to have four. Outcome was the same either way..

 

[IAE Racing]

I don't remember the exact degree of the bend. 5Kids just suggested lock down the NDFW either way. There really hasn't been much testing done on Pinecars. Sorry I don't have a quick link to axle bending, but same as a regular axle.

 

[garthbro]

I'm wondering whether I can bend the axle any myself...have to go back and read the rules again.

If I cannot modify the axle (or if I don't go through the trouble to do it), I figured I would at least raise one of the front two wheels (i.e. three wheeler) to reduce rolling resistance.

I'm also thinking that there may be enough slop in the axle (i.e. not perfectly straight) and/or the axle slot in the wood block (i.e. not perfectly squared with the body), that I can get some position of the axle going where I will still get some turn into the rail to give me some rail rider effect. I'm thinking this might be my best approach considering the limited adjustments I can make on alignment.

 

[IAE Racing]

We've discussed angleing the slot in a different thread where axle bending is not allowed. If you haven't built your car yet, cut your front axle slot at a slight angle. ~2deg, cut your NDFW slot a little deeper. (the more forward would be your DFW) Now I haven't seen any out of square slots on a pinecar block (unlike BSA blocks) but out of the five blocks we had this year, there was close to 3/8" difference in where the wheel base was positioned front to back. KID YOU NOT! But yes raise one and lock it. The slop in the axle/wheel won't steer.

 

[IAE Racing]

Don't forget to polish your axles and bores.

 

[garthbro]

Thanks for all the great feedback..races were this morning and won!

Here's a quick summary of what I did:
- Polished axles
- Polished wheel bores and hubs where they contact body
- Made sure rear axle was adjusted (was able to rotate to get where I needed) so that rear wheels were aligned
- Filed front axle slot so I was able to (1) raise front left wheel (3 wheels of contact only) and (2) angle axle so front right wheel was DFW and riding on the rail
- Worked in plenty of graphite on the body contact points and on the axle and wheel bores

By winning today, we get to move on to races next weekend that include more winners in our area. To prepare, do you have any suggestions on the following:

1. Cleaning the Car
I'm wondering if I should clean the wheels and axles of graphite and next weekend repeat the process of working in "fresh" graphite into the wheels axle. If I leave the current graphite on the car all week, will it start to "gum up"?

2. Eliminating Wheel Wobble
While I was working graphite into the car by spinning the wheels and repeatedly applying graphite, the rear wheels would spin smoothly and seemed well-balanced. However, both front wheels had quite a bit of wobble and "chatter" in them when I would spin them. To me, this seems to indicate an area where we could possibly improve performance.

I would assume that the problem lies in the wheel bores. Should I try to polish the wheel bores again and see if I can improve the spinning balance of them? Any suggestions?

Thanks again!

 

[DerbyDad4Hire]

Look for a burr on the outer hub of the wheels.

 

[IAE Racing]

Congrats!!

+1 on the burr on the outside of the bore.

Look down the bores, I would not most likely repolish the bores however. You may enlarge the bore too much. Generally it is not needed to "reprep" depending on how many heats you ran. Usuaaly just reapply more graphite.

If you do take the wheels off, you can polish the inside of the black cap where they meet the wheel. My fingers don't allow me to do this, so I don't anymore.

If you chose to clean the bores, I don't know if it warrants, Maybee one of the graphite days guys would chime in here, clean the bore with rubbing alcohol with a fuzzy pipe cleaner. The outside of the wheel though DEFINITLY wipe off the tread with rubbing alcohol after you reapply graphite.

To get the graphite grime off the car, use olive oil.

Since you got the fourth lifted, adjust your wheel gap on your DFW side close, but still spin freely. Then use a thread of cotton ball in the bore of the NDFW, so it won't turn or vibrate.

 

[garthbro]

Thanks for the feedback. After thinking about it for a while, I'm thinking I might do the following:

Rear wheels:
- Cone the wheel hubs (I did not do as much coning originally as I could have)
- Light sanding and cleaning of the wheel surface

Front wheels:
- Check the wheel bore for any burr that might be causing whobble
- If no luck, prep some new replacement wheels to see if I get a better balanced wheel
- Additional hub coning
- Light sanding and cleaning of the wheel surface

I ran about 12 races, so I think I'll take my chances with just another graphite application next weekend.

Sound appropriate?

 

[IAE Racing]

sounds good