Given I'm still on Holiday due to Chinese new year, and not having a lot else to do with everything shut (and I literally mean everything!), and not being able to go to the track and run due to yesterday's, umm, driver error, thought I'd sit down and have a fiddle with the car. Mainly wanted to try out how fast I can switch out between transverse and longitudinal motor (not as long as I thought), and the standard and IAS (the same
). I also wanted to check the weight balance with the transverse, which is something I could do even with the broken ball cup.
Finally, also wanted to make it a little easier to remove the top deck without poping off the ball cups. So excuse the following ramblings... I'll try and keep them to make sense!!
First up, Top deck ball joint
s. Given I've been regularly loosening the top deck screws as part of my general habits vs tweak, I was finding having to pop the ball joints off each time a little concerning. Could also see them starting to look ragged due to my pliers.. Anyway, I've switched out all the inner ball joints on the long links for Tamiya 8mm hexheaded Ball studs, and Tamiya ball cups with the top cut off... bingo, can now drop a 2mm wrench into the hex head, and not have to pop the cup off. Also means only one tool to take the top deck off the car, me likey!
Only difference is that the Tamiya ball joints are 0.5mm lower than the kit ones, so have to add an extra 0.5mm to the shims to raise the link back up to the correct height.
Next up, Transverse motor switching
. I was really surprised at this, as it didn't really take as long as I expected to switch this over as I thought. Could easily have it completed and ready to go in ten minutes at a push, as long as you don't have to resolder wires (truth be told, I was waiting on some 14AWG wire before I could do this, all my stock is the wrong colour... yellow, urgh!). In terms of motor positioning, I think I'll forget looking for a motor with a short shaft, and buy what I think will be fastest and cut the shaft down. The X12 I had for trial fitting only required 2.75mm of shims between the motor bracket and mount bar. Even then had a comfortable amount of clearance between the end if the shaft and the centre shaft, so could still bring the motor in closer if needed.
Whilst I had the car in that config, I wanted to check the weight balance as well, as having the motor hanging out is always going to change the balance. With the transverse setup, I've found having the cells flush with the side of the chassis gives a pretty good L-R balance, and tweaks up well on the station. For the transverse motor, I had to move the cells out 4.5mm from the chassis edge to achieve the same L-R. Couldn't put it on the tweak station, but I'm pretty confident that will be good too when I can.
Obviously this would change a bit with a) lighter electrics (I'm using Savox 1251MG, Sanwa RX451-R, and HW v2.1 120A), and b) motor spaced out differently. But that should give a pretty good ball park figure to work in.
Thirdly, IAS trial fitting
. Ok, got to admit, this is the one I've kept putting off testing before, mainly as it looked like it would require a pretty big dissemble to fit, and I always had other things higher on the list to run through. Anyway, sitting down with some time to think out it, I figured out it's not so difficult to switch out, and with a bit of magical screw balancing through holes, can fit it without taking out the front gearbox
. Wouldn't be as quick to fit as the transverse, but a good 20mins, plus setup time on the gauges (as the links need shortening), and would be good to go.
Anyway, the above then led me to have a look at the bump steer spacers
, and this is when I realised that I haven't been adjusting the bump steer spacers when sorting out the castor...
This was especially noticeable on the rear, in that I was gaining a fair bit of toe-in with compression on the rear, and this would possible explain the mid-corner push I had been experiencing. Since the first test, I had reduced the rear castor from 7.5° to 2.5°, so quite a large change. Also on the front I was having a bit of toe-out under compression, although I was running the spacers that I had seen on other setup sheets.
To solve the front, I dropped 0.5mm shim out off the rack, whilst at the rear had to switch from having 1mm inboard, to 1mm outboard. This pretty much made the links flat, and completely removed any bump steer.
I think this is a pretty important point to remember, so lesson learned for me.
As a question for Oleg, do you have any advice on how to adjust the bump steer spacers when adjusting castor on the front/rear? Or just play it as you see it?
Anyway, enough of the ramblings... I'm off to bed, one more day of holiday, then the city wakes back up again