Savage XL conv. problem with Reverse module
 

Hi all,

I finally got to do the first little road test of my XL conversion project.

The Savage XL it pretty standard: the 3 speed tranny, stock brakes, 52T spur, 15T pinion, own designed motor mount, HPI reverse module and mixer.

Everything seems to work smooth on the bench. But on the road I have problems with the reverse module. After giving full throttle forward, the reverse module decides to go into reverse!!! ugghh nasty sound!

I followed the mixer setup program several times. I tried to use either the ESC signal or brake servo signal as input CH2 on the mixer. It stills pops out of forward. The servo actually change position, it's not just some mechanics being pushed. I use a Graupner C577 servo for the reverse module.

I dont get it - how is it possible? I only run on a 7.2V NiMH pack, so the car runs real slow (I dont want to break anything at this stage!).

Anyone having experience with the reverse module and mixer?

Thanks for any tip, hint or comment!

- Lars

1.)Why are you using one? Seems expensive and complicated.

2.) Did you try reversing the Thr signal and switching two wires on the motor?

3.) You will prolly just blow up the Rev module anyway. Lock the tranny and use motor for brakes and rev.

1), 3) I read the threads about locking 2. speed etc. or using the kershaw mount etc. And yes, I might break something - but right now its just exciting to make all the complicated stuff work! :-) Sometimes I have more fun screwing (on the car) than actually driving! :-))

2) No, I will definetely try that! I think as it is now, it is like in the instruction manual.

why are you linking or mixing it? your third channel should be seperate. you only use the third channel when you shift into reverse, so if you mix it with another channel it is not seperate.

there should be a switch or lever or button that activates your third channel.

unmix it. It sounds to me like when you hit the brakes it shifts, which is what it would do if you mixed it with channel 2.

you created your own problem!:yes:

Ok, here is what I do:

Ch1 is of course steering. Ch2 throttle. Only forward makes sense (on the ESC I enabled only forward mode). The brake servo is using Ch3! So it is mixed with Ch2 on the transmitter. In the car, the HPI mixer 'listens' to the brake servo (or ESC signal) and activates the reverse servo when the brake has been activated for 3 seconds.

So, it should only be able to switch to reverse after full stop - brake for 3 seconds, not just when doing releasing the throttle or doing a quick brake.

Can I wire it differently?

after your last post and re-reading the first post it sounds to me like the reverse mixer is engaging after 3 seconds of throttle, rather than 3 seconds of brake.

it sounds like you need to reverse the servo direction on channel 3

you could also just run a y cable and use the esc and brake on ch2 and use the 3rd channel independently (without a mixer, that's a kitchen appliance) to shift the reverse servo

I have run a 2 speed in my savage for a while and in the end I didn't like it. It tends to shift at the wrong time and due to the torque of the brushless cause the car to accelerate when you least want it too (eg. towards curbs). I would say grab the Flux single speed setup and use that.

If you really want your current setup to work though these guys are probably on the right track or is it possible that your using the brakes for longer then 3 seconds and thats why reverse is kicking in. I know my savage would take close if not longer then 3 seconds to stop. After one or two full speed runs and stops you can smell my brakes burning too.

Thanks for comments!

I did a further check of my system and found the rather disappointing fact, that the HPI mixer will move the reverse servo without notice - not only when the brake has been activated for 3 sec! It seems to happen when I pull the throttle in a lively manner (without braking). crap..

So, I took out the mixer and used a Y cable so the brake and ESC is on ch2 and ch3 is dedicated to the reverse function. It works perfect. Except I have to be carefull not to push the ch3 button when the car is moving!

This leaves me ready to continue, throw in some more lipo cells and get more speed. I am excited to see if if the 3 speed gearbox is any good - otherwise I do have a Kershaw mount lying around that I could use.

I find it really neat to have the servo operated brakes, instead of using battery power. Should give me a little more running time, right?

i hate to tell you this, but, the 3speed tranny is much weaker than the 2speed. the 3speed has narrower gears to allow the extra 3rd speed gear. the gears in the 2speed are much wider and will withstand much more abuse.