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Body Post Repair and Replacement

by Dickie Pearson & Steve Sawtelle

Copyright (c) 2008 by Dickie Pearson & Steve Sawtelle - All Rights Reserved.

Copyright (c) 2008 by Slot Car Corner LLC - All Rights Reserved.

 

Introduction

How many of your slot car bodies see limited use (or can no longer be used at all) because of broken/damaged body posts like the one in the accompanying picture? You don't have to race 1/32 slot cars very long to experience some sort of problem with the body mounting posts. While in extreme cases they may break right off the body, more often they crack or split. Body post cracking and splitting can have many causes - some common examples include using the wrong screw (too large in diameter and/or the wrong thread), over-tightening the screw, or excessive screw insertion/removal cycles. Whatever the cause, repairs typically involve replacing all or part of the post, reinforcing the existing post or filling/retapping the existing screw hole. In all cases, there is a good chance the repaired post will eventually fail again. This write-up will demonstrate a fresh approach to repairing body posts. In fact, serious racers may want to consider using this approach to beef-up the stock body mounting posts and eliminate the stock body mounting screws and their limitations altogether.

The accompanying picture shows the key to this approach - a small, threaded brass insert. The insert accepts standard M2 machine screws which will replace the stock body screws to secure the body. On the outside of the brass insert are "teeth" which are designed to secure the insert into a plastic (or as we shall see, metal...) tube or sleeve. This system offers another important advantage over plastic body posts and (metal) body screws. With stock body posts, even posts that are in good condition, body screws have a tendency to work themselves loose and in some cases, fall out altogether. In either case, the car's handling and overall performance is adversely affected (in extreme cases, the car may not be able to continue racing). Threadlockers (e.g. , Permatex, Loctite) are one potential solution; however, ordinary threadlockers are not plastic compatible. While there are special threadlockers designed specifically for metal-to-plastic applications, they are very expensive (e.g. Loctite 425). In contrast, the inserts shown here along with the mounting screws offer a metal-to-metal mounting system - this allows ordinary medium-strength (removable) threadlockers to be used to keep the body mounting screws exactly where you want them.

Special Thanks to Jan Levine who first brought these wonderful inserts to our attention!

Note: For your convenience, the high-quality components shown in this how-to article are available for purchase at the end of this article (simply scroll to the bottom of this page) or by clicking the following link to the Slot Car Corner Online Store.

 

Step-by-Step Installation Instructions

What follows are step-by-step instructions which describe and show how to repair or replace body mounting posts for a 1/32 RTR car. In general, this approach works best with cars/bodies having longer body posts - ideally at least 7/16" (11mm) long. The example uses an older-style Scalextric Nascar for illustration; however, the same techniques can be used on a wide variety of 1/32 cars. The "sleeves" used to secure the insert in this article are made from brass tubing; however, plastic tubing can be used as well. Brass and copper tubing have thinner (and stronger) walls than plastic tubing - this makes it easier to "nest" different sized tubing which is sometimes necessary depending on the size (circumference) of the body post.

Caution: Always wear safety glasses and follow all manufacturer's instructions and safety guidelines when using hand or power tools.

 

Here is an example of a broken body mount. Again, this is an older-style Scalextric Nascar body.

 

 

First measure the length of the body post. Note this body post is mounted at an angle to the underside of the body - therefore, one side is longer than the other. Be sure to measure the longer side. In this case, the post is about 9/16" long.

 

For this repair, I have chosen to use some 3/16" copper tubing (I didn't have any brass tubing at the time...) because it fits perfectly over the stock body post. Ideally the sleeve will fit snug but not so snug that you risk further damage to the post while sliding the sleeve on/off. Measure a length of tubing about 1/32" shorter than the measurement you took in the last step. The 1/32" is necessary to compensate for the height of the insert's mounting flange.

Note:  I could have used plastic tubing; however, it would have required fabricating a "nested" set of plastic sleeves (because of available o.d.'s) to achieve a similar result.

Carefully cut the tubing - here I am using a tubing cutter; however, a cut-off wheel mounted to a Dremel or small hobby saw (with the appropriate blade for the material you are using) could have been used as well.

 

Carefully remove any burrs from the tubing where is was just cut. For the 3/16" tubing be used in this example, a 5/32" drill bit makes it easy to remove the burrs.

 

Carefully cut off about 1/4" of the body post. This will allow the body mounting screw sufficient adjustment once threaded into the insert in a later step. Be careful not to cut the body post too short.

 

 

Use a sanding stick (or sandpaper) the remove any excess plastic flashing which may be present from the cutting operation. Apply a slight chamfer to the end of the post to make it easier to slide the tubing over.

 

Carefully test fit the sleeve over the remaining portion of the body post as shown.

 

 

Pay particular attention to where the sleeve meets the body (circled area). Because the body post is attached to the body at a slight angle, it will be necessary to modify the "bottom" of the sleeve to match this angle. For the copper sleeve, a small file made quick work of this task. If you are using a plastic sleeve, a file or sanding block could be used.

Here is the modified sleeve (circled area) - it is now perfectly flush with the bottom of the post where it meet the body.

 

Before proceeding, double-check the new post length and adjust if necessary. Do NOT secure the sleeve to the post yet.

 

There are a number of ways the insert can be secured inside the tubing/sleeve depending on the sleeve material. Since the sleeve in the example if made of copper, I've decided to solder the insert in place. Start by placing a small amount of flux around the portion of the insert which will go inside the copper sleeve. Thread an M2 screw into the insert to make it easier to hold/position.

Note: Adhesive designed for joining metal parts could have been used as well. If you are using a plastic sleeve, be sure to use a plastic compatible adhesive.

Use your soldering iron to "tin" the outer portion of the insert. You only need a small amount of solder (just a thin layer). Wait for the insert to cool before handling.

 

Place the insert as far in the sleeve as it will go. Carefully hold the insert and sleeve as shown using a pair of needlenose pliers. Use VERY GENTLE pressure on the pliers while heating the joint - once the solder starts to flow, the insert can be pressed so the "lip" is flush with the end of the sleeve.

Here is a close-up of the completed sleeve/insert assembly.

 

 

Install and secure the sleeve onto the body post "stub" using your favorite adhesive.

Note: If you want to further beef-up the post, you can run a bead of hot glue or your favorite eposy (e.g. J.B. Weld) around the base of the post where it meets the body.

Now lets turn our attention to the rear body mounting post. In this case it is not broken; however, we'll go ahead and replace it with the sleeve/insert setup to reduce the risk of problems/failure in the future. Note that like the front post, the length of the post is not uniform around its circumference. The rearmost portion of the post intersects with the body at a sharp angle - this will require cutting a notch in the sleeve to ensure it will slide onto the post as far as possible.

Follow the same steps described earlier for the front post - measure the longest portion of the body post and cut a piece of brass tubing about 1/32" shorter (to compensate for the flange on the insert). For this particular body post 3/16" tubing provides a nice snug fit - there is no need to "nest" additional pieces of tubing.

Here's a tip to make working with the short sleeve easier. Slide the short length of sleeve over the flat end of a drill bit - in this case, a 5/32" drill bit fits perfectly inside the 3/16" tubing. Position the sleeve so the end you are cutting/filing sticks out just beyond the end of the drill bit. Using your fingers, you can easily "secure" the other end of the sleeve to the drill bit.

Use a Dremel with a cutoff wheel to cut the notch in the short length of sleeve. Test fit and use a file to fine tune. Use the drill bit to clean out the sleeve after each cutting/filing operation.

 

For this particular post, the notch should look something like the one shown in the accompanying picture.

 

Test fit the sleeve over the body post and check for overall length. Again, the sleeve should be about 1/32" shorter than the post to compensate for the "thickness" of the insert's flange.

 

Next about 1/4" of the post will be removed - mark where the cut should be made and use a Dremel with a cutoff wheel to make the cut.

 

Use a sanding stick or some sandpaper to carefully remove any flashing which may be present from the cutting operation. Apply a slight chamfer to the end of the post to make it easier to slide the tubing over.

 

Test fit the sleeve over the post stub to ensure everything fits properly. Make any last minute adjustments which may be necessary.

 

Apply some adhesive to the body post stub, slide the sleeve on, check and adjust the position of the notch and set everything aside to dry.

 

The completed repair (front post) and upgrade (rear post) is now complete. The body is now ready for mounting and adjustment. The body retaining screws can be held in the desired position using medium strength threadlocker.

 

Here are some more examples of the sleeves/inserts installed on a variety of manufacturer's bodies. All are excellent candidates for the sleeves/inserts because the body posts are relatively long. The first example shows a Slot.it 956 Porsche where sleeves/inserts have been used to strengthen and enhance the stock body mounting posts. Like the Scaley Nascar, the 3/16" tubing was the perfect size for the body post sleeves which secure the inserts.

 

The next example is a Ninco BMW. Sleeves were fashioned using 3/16" brass tubing. No angles/notches were required in the sleeves as the body posts have a uniform length around their entire circumference.

 

The last example is a Scalextric Porsche 911. Sleeves were fashioned using 3/16" brass tubing. Both sleeves required angles/notches to ensure a flush fit to the body.

 

Summary

Repairs (or enhancements) to body mounting posts are straightforward using the specially designed inserts and sleeves shown in this article. No special skills or tools are required - the results is a body mounting arrangement which is much less prone to failure than stock posts or posts repaired using traditional methods. This system also allows the use of threadlockers to secure the body mounting screws exactly where you want them without risk of damage to the posts. Scratch builders can also use these inserts when fabricating custom body mounts.

NoteFor your convenience, the high-quality components shown in this how-to article are available for purchase at the end of this article (simply scroll to the bottom of this page) or by clicking the following link to the Slot Car Corner Online Store.