It was a mixed bag this weekend. By the end of these two days I have a direction I want to pursue with RWD.
No photos to show. Forgot my SD card again.Read only if you have Rear Wheel Drive.
First of all.. I apologize to all that I crashed into and spun in front of today. SORRY!
My drift package rear wheel drive setting is a painful process. I'm trying to set this up to run without gyro on polished concrete. 7.5T turn motor with the endpoint at 14% is hardly desirable and will need to be changed. But I made a lot of progress even with this combo in place.
The chassis itself handles fine. In fact I think it handles better than my DRB off throttle sliding beautifully into corners, but the struggle with accelerating 2Kg through rear tyres only creates an issue. That means searching for the "grip" you need. through tyre choice, weight, balance and setting
Low speed with a lot of steering lock in the slow haipin corners is a struggle for everyone.
When these Rear Wheel drive machines are running very slow almost all of them are spinning even with gyro. With about 5 MST FXX - VIP at the track today it was good to see a bit of variation and reasonable success.
I think in a high speed circuit they all would have no problem, but that point where you almost stop during a hairpin is a real issue. Taking the outside line usually eliminates this, but it is something that needs to be looked at.
I tried the following tyre combos and various suspension settings and throttle settings on each..
F: Spice Carpet
R: En Route Carpet tyres.
Result No- traction
F: Spice Carpet
R: HPI T-Drift
Result limited- traction
F: En Route Carpet tyres.
R:HPI LP38 T-Drift
Result average - traction good control
F: Spice Carpet
R: DS Soft
Result decent traction
F: Spice Carpet
R: HPI Rubber
Result no drift and off throttle stopping. No sliding.
F: Spice Carpet
R: Raikou tyres (medium?).
Result decent traction - pretty good actually.
F: Spice Carpet
R: RNR tyres.
Result Good- traction
I persevered with these for a while, balance was not great,
F: DS Soft
R: RNR tyres.
Result Good- traction, good steering but easy to spin.
So in the end. Others were running DS with gyro machines. so I reverted to these and really tried hard to get my driving, the balance of the throttle and the tyres in check.
F: Spice Carpet
R: DS Soft
Result decent traction and nice sliding. bit zero rear camber. I'll be shaving these flatter for a better contact patch.
I've added more weight to the front and now it's pretty decent and has started to eliminate the slow corner issue.
I can definitely run laps without spinning at similar speeds to 4wd now but there's a few issues I need to address before I can confidently "hook it up everywhere".
1 is castor.
I'm not enjoying the way a lot of castor is behaving. I'll be moving to a low degree only castor setup in a move to try and enliminate front end droop changes due to castor in a move to get a "Flat" front end. Instability under lock to lock steering changes is an issue.
I find up to about 40 degrees I am pretty happy but over that there are some issues. the transition of the angle of the front tyre is a problem. At the moment I'll try to avoid the ugly round MST tyres.
2 is motor.
the current motor is extremely hindered and needs to be changed.
I'll probably swap the 17.5T in
3 is differential.
I think to overcome the issue of slow speed high angle cornering a differential (albeit a very tight one) might be worth a try,
Rear wheel drive is looking real... only some of the time. so I want to head in the REAL look direction. similar to the Jack Style setups.
more to come.
Looked good for the time I was there, I think the fact your running no gyro is a credit to the skill level.
ReplyDeleteToo kind Neale. It wasn't until about 5pm I kind of had it sorted. But it's all fighting against bad design. So I'll change some things and try again.
Deletethats how we roll. test run test run test run. At least i got exercise doing squats all day. picking my car up off the track and putting it down again. I think 100 changes or more.
For the tight hairpins, maybe try adding some unsprung weight to the front arms or hubs?
ReplyDeleteI found that when some of our locals started adding some unsprung weight, it made the cars much easier to drive through the tighter corners. They added 5g each side. Mind you these were FR-D's...
Really interested in the development of this car though, I've been slowly rebuilding my leftover Doripake parts into a budget RWD car as well :D
funny you should say that. the last thing I added on Sunday was weight to the front end. temporarily on the Body though.but it helped a lot. I added 35g each side haha!
DeleteMy car is heavy because I want it to flow and hold the line without too much "twitchiness". I found the light weight cars just stop almost instantly when there is no throttle. I'm not a fan of that. I want mine to have an ability to hold a long handbrake situation like my other cars and the only way to do that is with weight.
Yea, I know that stop and go off throttle feeling all too well. The biggest difference I felt when driving the FR-D was the 5g unsprung weight on the front arms. It really helped drive the car through the corners. An additional 25g was added to the front bumper after, and the car basically felt like it was driving itself after these 2 changes.
DeleteI'm not sure how much this will help you in tuning your doripake though, considering the car has a complete different weight distribution, and I was driving a car with a Gyro :S
My experience with RWD is very limited right now >.<
Me too, but I can "see/feel" what the car is doing.
ReplyDeleteI've tried to go up in grip on the rear tyres but there's a limit where they don't slide anymore even though it is stable under full power slides. when off throttle grip comes into play (ie the handbrake scenario) the reality is instantly gone when the cars stop too quickly. I like my cars set up to have controlled slide a long way so I can go deeper into corners. I played around with the front end last night. But without a Japanese shop just around the corner obtaining the parts I need isn't going to happen in a hurry. So I'll be trying the constant grip front tyres from MST to get the smooth control at full aft angle without droop changes.
Yes!! That's one of the first things I noticed when I drove RWD. Every change you make you can see and feel the effects it has on handling, while on my CS car some of the changes go completely unnoticed.
Delete