Carrera Bmw M-1 (UPDATE)
Posted: Fri Mar 11, 2016 12:25 pmAll right Fellers...I have not been a fan of the stock wheels since Dave posted the pics. I think the car is absolutely beautiful but the wheels let it down. I understand that they have to be correct when making a car but that doesn't stop us consumers from improving on those looks (IMO).
First thing to do was to see what Carrera car I had that had some wheels that would an acceptable replacement. I got lucky with the Porsche RSR. It had to look I wanted AND had the same wheel track as the Bmw. Time for dissection..
Rear: As seen in the pic the wheel track width and the spacing is exactly the same so the axle was a straight swap. Nothing was changed. The only difference was the rims are wider on the Bmw but the offset is on the inside. Not an issue.
The Bmw uses different gearing than almost all of the other Carrera cars hence there is a size difference in the pinion and sidewinder gear. When you swap to the RSR axle the gear is taller so you must change to the smaller 10T pinion on the motor at the same time. Again a non issue.
Front: The axle track was almost the same. The Bmw was about 1mm wider. Not enough to make a difference. The only modification I had to do was to take the plastic axle shims off of the RSR axle and sand them to 1/2 of their current thickness to allow the axle's brass bushing to sit properly in the chassis.
Tires: This is where it gets interesting. Now you have to use the RSR tires because of the wheel swap. The front tires off the RSR were just a touch taller than stock so they were trued down to the right height. The rears..... Starting with the stock PG RSR rears tires they were much to tall. After spending a lot of time on the truer I managed to cut 1.5 mm off the height to where they would fit in the wheel wells without rubbing. After a lap around the track (Mag out) the car handled terrible. Reason. The rear tires were still about 2 mm taller than the stock tire raising the chassis off the track. Off come the tires and figure out a plan B. :doh: What I need is a rubber band thick tire to offset the taller RSR wheels. Looking at Carrera's offering I couldn't find anything I could use. I looked at the stock rear tires but they were too wide to make work. I was stuck till I looked at the stock Bmw front tires. They were about the same width. The ridge on the inside of the tire was wider than the ridge on the rim but it would work if I glued the tire exactly in the center of the rim. I measured the overall size and it was almost the same as stock. All right lets do this. After the setup and trueing the tire it ended up being just a touch smaller than stock. Back to the track. Car ran well but not great.
I started looking at the chassis height and compared it to my Carrera GT cars and it was still anywhere from 1-2mm taller at the chassis. No wonder it doesn't run as well. I'm not going to just run the Bmw's as their own class. To start with I'm not really thrilled with the current Bmw offerings so this may be an orphan. Disappointed yes. I wanted this car to run with my GT cars but until I can figure out how to lower the car some more...... :think:
I may have some ideas though... :shhh:
Dave
First thing to do was to see what Carrera car I had that had some wheels that would an acceptable replacement. I got lucky with the Porsche RSR. It had to look I wanted AND had the same wheel track as the Bmw. Time for dissection..
Rear: As seen in the pic the wheel track width and the spacing is exactly the same so the axle was a straight swap. Nothing was changed. The only difference was the rims are wider on the Bmw but the offset is on the inside. Not an issue.
The Bmw uses different gearing than almost all of the other Carrera cars hence there is a size difference in the pinion and sidewinder gear. When you swap to the RSR axle the gear is taller so you must change to the smaller 10T pinion on the motor at the same time. Again a non issue.
Front: The axle track was almost the same. The Bmw was about 1mm wider. Not enough to make a difference. The only modification I had to do was to take the plastic axle shims off of the RSR axle and sand them to 1/2 of their current thickness to allow the axle's brass bushing to sit properly in the chassis.
Tires: This is where it gets interesting. Now you have to use the RSR tires because of the wheel swap. The front tires off the RSR were just a touch taller than stock so they were trued down to the right height. The rears..... Starting with the stock PG RSR rears tires they were much to tall. After spending a lot of time on the truer I managed to cut 1.5 mm off the height to where they would fit in the wheel wells without rubbing. After a lap around the track (Mag out) the car handled terrible. Reason. The rear tires were still about 2 mm taller than the stock tire raising the chassis off the track. Off come the tires and figure out a plan B. :doh: What I need is a rubber band thick tire to offset the taller RSR wheels. Looking at Carrera's offering I couldn't find anything I could use. I looked at the stock rear tires but they were too wide to make work. I was stuck till I looked at the stock Bmw front tires. They were about the same width. The ridge on the inside of the tire was wider than the ridge on the rim but it would work if I glued the tire exactly in the center of the rim. I measured the overall size and it was almost the same as stock. All right lets do this. After the setup and trueing the tire it ended up being just a touch smaller than stock. Back to the track. Car ran well but not great.
I started looking at the chassis height and compared it to my Carrera GT cars and it was still anywhere from 1-2mm taller at the chassis. No wonder it doesn't run as well. I'm not going to just run the Bmw's as their own class. To start with I'm not really thrilled with the current Bmw offerings so this may be an orphan. Disappointed yes. I wanted this car to run with my GT cars but until I can figure out how to lower the car some more...... :think:
I may have some ideas though... :shhh:
Dave