Slot Cars Adelaide
MJK FJ Holden Kit - Building Tips
The MJK FX/FJ Kit comes with most parts to build the kit. It is 1/24 Scale. At FPR we allow different car models to be used on the MJK FJ Chassis. Examples are the S Series Valiant & the Charger , Holden Monaro & Falcon GT. The class is based on the full size Cams Group N class. The bodies used are Vacuum formed. So Here are some bulding tips for the FJ Holden but most of the tips apply to the other makes of cars. The wheel base does vary for different bodies but the MJK is adjustable for most Group N cars.
The axles that come in the kit are longer than needed for the FJ . I have found cutting to around 60mm long fits the FJ front & Rear. I grind three flats on the axle for the grub screws that secure the wheels and crown gear. The flats for the wheel start 2mm in from the end of the axle and are about 3mm long. The Crown gear flat is central and about 4 mm long. The brass tube spacers ( not supplied in the kit) are from Stock # 128 - 5/32" x 0.14" (3.97mm x 0.35mm) tubing . To cut the tube I drilled a hole through a 30mm wide block of wood - near the end,then cut the tube with a razor saw. The tubing lengths are: 5mm for the rear - allowing for thrust washers against the axle bushes. The front spacers are 7mm for the front - no washers needed. Shown are the tools I used for cutting the axle. There is a Dremel with a cutting disc and a grinding wheel for the flats. Firmly mount the axle and use eye protection for cutting.
The lower photo shows the axle in the chassis. Make sure the bushes are pushed fully into the chassis. Some chassis holes may need a little relief with a file if the bush is hard to drive fully into the chassis hole. Also as you push the axle into the bushes see that it lines up exactly with the bush. Slight alignment by gently bending the bush support may be necessary. The line on the wheel with Texta is to indicate the grub screw position . When the tire is fitted to the rim the grub screw can't be seen. So for wheel removal the tire can be lifted where the wheel is marked to locate the grub screw. I also lined up the flats on the axle to assist with assembly location.
I gluing the tires to the rim make a puddle of superglue (Bostick Super Glue is excellent) then with a toothpick or meat skewer ( wood) dip the tip into the puddle and put 4 around the rim hub and toward the outer of the rim hub. Have the tire mounted while doing this and lift away from the rim for each dot of glue. Stay away from the grub screw hole with the glue so the wheel & tire can be removed & replaced.
Motor Set up
The pinion is not fitted to the motor so a pressing device is needed. These are available from model suppliers. They usually are designed to remove the pinion as well. Other pressing methods can be used . the push should only engage the pinion and the motor shaft at the opposite end - not any force on the motor case or bearings.
The pinion is pressed so that 2mm of the shaft is protruding through the pinion. To do this the press foot must have a hole to accept the shaft end and the push is only on the pinion - not the shaft at that end.
That 2mm of shaft protruding through the pinion has to be removed by either cutting or grinding. It will contact the grub screw in the crown otherwise. the contact is shown in the lower picture. This occurs even with a reasonable flat on the axle.
I found it easier to fit the motor retaining screws were easier to fit in the horizontal holes at the pinion end. The motor also seems to sit flatter on the chassis. The vertical screws seemed to lift the other end of the motor off the chassis. The spacer plates on the front motor bracket could of been used to space the motor up but using the horizontal holes this was not necessary so they became just spacers to stop the chassis screws protruding through the chassis. When all is correctly in place a dob of superglue on all the mounting screw head (or thread) to chassis should stop them coming loose. There are other operations to do but should be fairly straight forward -any queries contact me , John [email protected]
Befor painting the body it is best to use a suitable tape along the sill to stop tearing where the body retaining clip fits. I use Tara Tape from USA but there may be other similar tapes here in Australia. I used the full width of the tape on the inside and outside of the sill. It probably could be 2/3 the tape width and be satisfactory,
It is best to locate the clip holes in body while they can be seen though the body an tape. Take care to get the body at the right hieght and the wheels in the correct position in the wheel arch. I run the body mount plates slightly loose. this is done by loosening the screw where the mount is attached to the main chassis. I secure the screw with super glue once the body mount float is adjusted. It is best to do that before locating the body.
Before painting wash the body inside & out with water & a small amount of detergent. while still wet obtain a small micro fiber block (usually there is one in the kitchen cupboard at my place) With the Micro fiber rub the surfaces to be painted - inside the vacuum body only ( not the windows). When done the surfaces should appear slightly "milky" so the surface is now ready for painting.
I usually do the chrome bumpers & trim as well as the brake lights. If spray in the body with the special poly carbonate paint ( used on RC bodies) all masking will have to be done first. This paint usually is followed with a coat of black of the same type of paint. Tamiya has a big range of colors now because of the RC boom.
I use the standard brush on water mix Tamiya paint with reasonable results. ( do not use any form of lacquer paint as it will damage the vacuum formed bodies). I do the cutting in around windows & headlights first with a small brush . I then paint the rest with a chisel brush about 6mm wide. This gets the paint on quickly with less brush marks , Try applying with the minimum brush strokes. It will take 2 coats usually. Do both coats with the minimum of brushing, The highlighting chrome trim takes a steady hand and may be best not done if you have trouble there. Best to practice be for trying it.
Decals are available from Patto's in NSW. http://members.optusnet.com.au/pattosplace/home.html He has a very nice range of stickers now. he supplies 3 sizes of roundels on separate sheets as well as different styles and sizes of numbers to stick in to the roundels. Sheets of sets of numbers and advertising are also available,
Have Fun! - John
The MJK Chassis Body Clip - fits most MJK chassis
Making your own clips
Hi, I have done a diagram for you . This should enable you to make your own body retaining clips for most MJK chassis.
I made a jig to do it . But I only use this to do the 38mm length bend . The rest of the bends are easily done with needle nose pliers - using 0.07mm piano wire.
You should not need a jig really but they are simple to make.
The piano wire is available at Aero Flyte on Goodwood Road and many other hobby shops .
Here are the dimensions for you . You have to do a slight adjusting to line up the end of the wire to line up so it goes in easily. Do not adjust at the “Z” end of the clip though.
If you print this off it should be the correct size but check the measurents in case .
For Sprint Plus chassis the 38mm length becomes 32 mm.
I suggest you draw a copy of the clip full size to use as a pattern.
or download & print the PDF Click this link.