The Cartrix GP cars are nice looking. But There is a few things that have to be done to get good performance .
The guide should be Ok for most racing if the braid is changed. I have found Slot Car Corner braid to be good for this application.
The most common problem is the pinion splits and becomes too loose to drive. I replace the pinion with a Plafit 9 tooth plastic and the problem is solved.
However before replacing the pinion I would suggest fitting a BWA 14.6k FC130 motor.These give a bit more power in most cases but not excessive The motor is a bout $7 and the pinion comes in a pack of 4 for $4.
Once the motor has been fitted & the gear mesh is correct place a drop od supper glue on the top of each side of each of the plastic motor bracket this is flowed to the end bell on one end and the can on the other. The four dots shouls be enoufg to hold the motor. They can be cut to remove the motor. Alternatively the motor can be wired in through 2 small holes drilled in the chassis alongside the motor can.
Next replace the rear tyres with DArt Canada or MJK Vintage Ninco. The original tyres are too grippy on most tracks & lead to tipping in the corners.
Also the tipping is due to the front axle being free to move up & down.I found an easy fix to this . I used the rear axle bushes to fit to the front. Plastic bushes salvaged from a Scalex car would do the job. I used the MJK plastic bushes.
First remove the body top and slip off one front wheel wheel. Slide out the front axle. Open up the hole in the plastic bushes to allow the axle to run freely - can be a bit sloppy. Get 2 of 3/32" axle spacers about 3 mm long. Slide a space to behind the remaining wheel . Slide on the two enlarged axle bushes then the final spacer and the wheel first removed . If the tyres are fitted to the rims & the rima are tight on the axle the front tyres can now be trued on the tyre lathe - using the new bushes assembled on the front axle.
The chassis with all tyres & wheels fitted can then be placed on a tech board. This will get the front axle height correct while the bushes are super glued to the chassis. Careful not let the super glue get inside the bushes & glue the axle. The glue is just to hold the bushes in place so it is not critical as the body top recess will hold the bush in place as well. However make sure the bush is attached to the chassis .
Make sure the axle is very free to turn and spins freely.
Use 2 of the Slot.it 2.2 mm brass body retaining screws to replace the body shell. Adjust the screws so the body is free to rock on the chassis . This may leave a slight gap along the join to the chassis . It is worth it though. The car will be a lot more smoother and better handling. It does improve the situation of de-sloting on FPR going up the hill on Blue lane.
Gluing the tyres to the rim is not necessary with the MJK tyres. The DArt are softer but you may be able to get away without gluing. Sand tyres to true and round the corners inside and out is important.
Lube the gears and the trunnion where the motor shaft runs to keep the mesh. Use the correct grease for the plastic gears. Lube the axle bushes front & rear. Also the motor bush on the can end - not the end bell bush as it may get on the brushes,
You should be right to do some quick laps now.
I did the same procedure to the Kurtis Offy . It does have some suspension links that get in the way.They either have to be either cut or removed to get the body to sit closer to the chassis . I left it a bit loose with the cap & will work on that later. The Offy runs well though and is clocking 6.7 secs on FPR green . The BRM P35 does 6.6 sec. Both have the BWA 14.6k FC 130 motor
The Lotus 16 still has the Cartrix motor and does 6.8 secs.
Those times are very close if not the same as the Before 70's GP Cars fitted with the BWA 14.6 FF slimline. So we may be able to mix them in races. if we wish.
The after 70's GP's with he same ff motor get down to 6.2 secs so they will have to run separate at this stage.
The bushes are added and super glued to the outside upright axle guides and also to the radius on the chassis. The top shell fits over the groove in the bush. The shell radius may have to be enlarged slightly to clear the bush .
The front tyres have been trued and coated with Bostick Multibond.
do not use the Multibond or other acetone glue on the plastic bits .
The axle spacer is between the hub & the new plastic bush.
have had the rear axle bush brackets broken - on receiving the car. In that situation I would suggest fitting a new axle and a slot.it 27T crown gear because the rear bushes have to be super glued to the remainder of the bearing bracket.
I fit NSR 3/32 oilite or similar bushes . With the axle in the bushes for alignment put the super glue on the brackets. Push the bearings & the axle into the correct position. Hold until the bushes are fixed by the glue. Once the super glue is set use super glue again to replace the loose broken piece of the bracket. Once that is secure cover with Araldite ( super strength is the best but 5 min. will do the job) . Make a gusset to the chassis with the Araldite to strengthen the bracket s to the chassis and loop across the top of the bushes to help retain them.
The changing of the axle is necessary as the original Cartrix axle has no clearance
in normal 3/32 bushes - or replacement alloy wheels . Changing the axle & bushes means the holes wheels do not have to be reamed out . I replaced the bushes because the original are sloppy on the original axle - therfore no use on the replacement 3/32 axle.
Because our FPR states the wheels have to be original plastic I made a hybrid wheel .
This was from a PLafit 1/32 scale wheel . I cut off the rim & reduced the center to fit inside the plastic original hub plastic wheel . I did this to retain the required plastic rim. The hubs of the original rims had both split so the wheels were not retained straight. This happened on the Lotus 16 rims . The BRM & the Offy seemed good.
Also the axle brackets were ok so I retained the orginal axle assembly and wheels
Even though the bushes have play they seem to operate OK
This is a repair to cracked hubs so the legal plastic rim can still be used .
A lathe is required to do this . Also a 3/32 drill blank to mount the completed assembly on & true up the plastic rim if out of true. I used Araldite to glue the plastic rim to the hub made from the Plafit Rim. Of course if the rule did not state "plastic rims only this procedure would be unnecessary as I would fit new DArt alloy rims with the correct insert for the car. Much better solution but them's the rules I guess.