Saturday, August 18^th, 2012

by Jeremy Bibbee (bibbster)

I'd recommend taking a look back at the initial review first to get acquainted with this model.

Spirit Porsche 936 from 2007

I've had this car for about four years, but sad to say it has had very little run time...until now! Why? Well...this car came to me at a time when I knew nothing about tuning a car. If a car went on the track and didn't run well, it just went back on the shelf or was sold. Thankfully, I chose to keep this one on the shelf because it has lots of potential. Upon running this car, it had a bad habit of fish tailing and occasionally coming up out of the slot so it got put aside. Guess, what? It still does it today, but we're going to fix that and a few other things. Let's get started!

The Parts: Take Your Pick!

When this car first came out 5 years ago, the after market parts were a bit scarce and/or pricey. Yes, there were some folks in the business back then but you had to really want to fix a car to place that order. Today the options are almost endless and affordable. We have at least a half dozen companies that offer every part that makes up a slot car, and some that specialize in just wheels, tires, guide parts, decals, bodies, and the list goes on. With the choices we have today, there isn't a car on your shelf or in your box that can't be tuned to run well. Of course, doing this can cost money, which was what stopped me from fixing my Porsche 936 back then. But after getting into tuning cars over the past couple years, it's amazing how much a car can be tuned without spending a dime. With this Porsche 936 from Spirit, we have a great base to work from so cost should be minimal.

For this review, all that we need to make this 936 scoot and more driver friendly is tires, braid, some weight, styrene, and a little TLC. The cost of parts was under $10USD, assuming you only factor the length of braid needed and the amount of weight that may be added. 

Parts used:

Paul Gauge Tires – Item# PGT-20115

Ninco Super Racing Braid – Item# 80103

PineCar Tungsten Putty – Item# P3922

Evergreen Sheet Styrene – Item# 2040 .020”(.5mm) 

Instead of the styrene mentioned in the parts list, I also like to use Shopping/Gift/Gas cards. I like these because they can almost always be found at the gas pumps for free. Folks leave them laying on top of the pump instead of throwing them away after they no balance remaining. Cheap way to get some plastic for building and helping the environment a bit as well. I have found that these cards glue up well if you lightly scuff the surface with sanding paper so it's dulled.

You'll also need various tools of the trade such as, sand paper, hobby knife, glue, etc. Since everyone likes their own flavor of tools, I won't list any, but I'll mention them briefly in the 'How-To'.

Is There a Body Man in the House?

As mentioned in the original review, my model also suffered from the tires rubbing the body, so in order to fix this, we'll first need to remove the body. There are three screws that hold the body to the chassis, with the front one being slightly covered by the guide blade. Using a small Phillips screw driver, remove all three screws; locations highlighted in yellow below.

In order to fix the body rub, I used a small piece of styrene to elevate the body above the chassis a bit. What this piece does is give the black plastic part that the motor detail is mounted to, and what essentially causes the body rub, a place to rest. It will not be enough to cause the center of gravity to change much so don't worry about that. And of course, this isn't the only way to fix it, just the way I chose to do it.

Using your hobby knife, cut a piece of styrene, 1-1/8” long (about 28mm) and 1/4” wide (about 6mm). Using just a tiny dot of CA glue (super glue) so you can check for fitment, attach the piece to the top of the chassis so that it extends past the rear edge 1/16” (about 1.35mm). If all looks good, and the body rests above the tires where you like, glue the edges of the styrene to the chassis. You may find that you need to add another piece of styrene, or sand down the piece you added a bit to get the body to rest the appropriate height to prevent rubbing the tires. Just adjust it as you see fit, and once that is done, you can paint this piece black or color it with a black permanent marker so it doesn't stand out.

 What a stiff...braid.

Now that the hardest part is done, no really, that was the hardest part, let's replace those stiff braids. You can use your favorite brand of braid for this since most any after market braid is softer than the stock braid. I chose Ninco as that was what the online retailer I purchased my parts from had in stock, and it's good braid. Simply remove the old braid by removing the guide wires and their eyelets from the top of the guide. A hobby knife blade under the lip of the eyelet to pop it out works well, or sometimes a fingernail will do. Once the guide wires are removed, pull the old braid out from the bottom of the guide, if it doesn't just fall out as they sometimes do. The stock braid is a little short for my liking so I cut mine so that it runs almost the full length of the guide. To allow enough braid to be inserted into the guide and run the length of the guide, you'll want to cut the braid at least 3/4” long (about 18mm). You can cut it longer and then just trim it once installed if you'd like.

Before you install the new braid, I prefer to re-route the guide wires. In stock form, they run up above the front axle. Normally this is fine, but due to the nature of the curvature of the nose of the body and the placement of the guide, the wires have a tendency to bind between the body and the top of the guide post. This prevents full guide travel and can lead to a car that is hard to control, and one that de-slots. To fix this, I simply remove the eyelet from the wire and run it between the axle and the bulkhead/axle block. You can see a photo of this below in the section discussing adding weight.

To install the new braid, put the braid down through the guide and then just before the trailing end of the braid goes through the top of the guide, squeeze the eyelet into the braid and push it through with the braid. It's easier to do than it is to explain, so do it the way that works for you.

Get a Grip, Will Ya?!

There are stock tires being produced by manufacturers these days are actually really good tires. They have decent grip and will get that slot car around the track pretty darn good. However, that's not always the case. The stock tires on this Porsche 936 are a bit to hard and just don't grip well, at least on my track. There are so many aftermarket tire manufacturers out there that a guy can go crazy trying to pick one. Some of these manufacturers are hobbyists like you and I, and they make tires for the pure joy of it. Some of the leading slot car manufacturers also produce tires to complete their full line of slot car products, but these are typically just the same tires you find on their complete cars.

How do you pick the right tire? Well, you try them all of course! Okay, try a few and pick the one that works best for you. I use urethane tires on my track (wood) as they are more forgiving as far as dirt goes, than silicone. I've used numerous brands of urethane tires from folks such as Yellow Dog Super Tires (Slot Car Corner), Paul's Slot Car Shop (Paul Gage Tires), and a few from guys that do some one offs for themselves or their club. In the past year or so, I decided to settle on one brand, and I chose that brand based on fitment, compound, and price; Paul Gage Tires. But with so many choices out there, find the one that's right for you, and by all means support those who support the hobby! There are some really great tires out there from some really great people!

With your choice of tire in hand, lets true them up. Before you true those tires though, you need to true those wheels. You can take a perfectly true tire and put it on a wheel, but if that wheel isn't true, that tire won't be either. I used to true my wheels and tires the old school way. It works really well, and most times will do the trick. You can read about that method HERE. I've since stepped up a notch and now use a Tire Razor, and although not necessary, it sure makes the job easier while looking cool at the same time! So, using whatever method you choose, true up those wheels, then install your tires on the wheels and true them as well.

Regardless of what brand of tire you use, you should glue them to the wheels. I would advise against using CA glue (super glue) because if you ever need to remove that tire, your going to have a mess on your hands. Either the tire will tear, the tire will melt into the wheel, or both. It was suggested by Paul Gage to use clear fingernail polish when using his tires, so that is what I use. It sets up fast, holds just fine and if you need to remove a tire it will break free without causing any damage. You can also paint your front tires with it to make them zero grip.

Weight for It!

For this 'How-To' I wanted to use a product that was new to me; tungsten putty. It's apparently used in the fishing hobby and pine car derby hobby, and maybe other places to. While not as dense as lead weight, it has one huge benefit; it's mold-able! You can also use modeling clay, Play-Doh, and other similar items, but none are as dense as tungsten putty...and tungsten putty doesn't dry out. This is a great item to use because it can be molded into crevices that lead weight can't. Not only did I use it here, but I used it in a recent Scalextric Lotus 49 project that kept me from having to cut off the drivers legs. That was a big deal to me and the driver!

I found that placing a ¼ ounce of weight on the chassis just behind the guide prevented the car from popping up out of the slot. This can sometimes be caused by front wheels that are out of round but on my model I adjusted them so they just barely touch the track surface for that perfect tripod effect. You may choose to place weight in other areas that suit your needs, or you may not need any at all. What I really wanted to do is bring to light another form of weight that is available for use in our hobby...we have so many choices!

The Sum of the Parts = Lots of Fun!

Like most models, with a little effort, and possibly a few inexpensive parts, this car can be made to run really well. Aside from the addition of the styrene, everything I have shown in this article can be carried over to other cars in your collection. So grab that car that gets little to no attention and try some of these tuning tricks!

I hope that you found this article useful and can take what you have read and improve the way
your car runs. I think you'll find that with just these simple tips, your stock Porsche 936 will come alive! If you run into an issue or have any questions at all, point your controller over
to the Message Forum and we'll help you out.

- Jeremy

Feel free to contact me about this article or just the hobby in general at bibbster@homeracingworld.us.

Thanks go to BRS Hobbies for their great service
and providing a place for me to buy the car & parts used for this article.