4PL or 7980th adjustment?

[Trainee]

I'm getting my Super all together finally after getting one new defective 7980th servo repaired by Hitec and can't seem to get it dialed in.

First, on the steering side, the servo horns I'm using don't line up 90 degrees from the servo when the servo is at neutral so I have to use the sub trim adjustment to crank it either left or right to about 85, front and rear, respectively. That, in turn, causes the bars on the radio display for those two channels to be partially shaded, where normally they would be centered at neutral.

My question there is: is this a radio setting? Or is it a servo setting that I would need to purchase a servo programmer?

Second, on the throttle side, going forward, the front ESC commands the front tires to start spinning first. If I apply light throttle, I can hold it so the rear don't turn at all when it is on a stand. Same thing happens in reverse, but the rear start spinning first and can be run independent from the front under very light throttle.

Again, is this a radio setting or an ESC setting? They are Holmes ESCs.

I have read through the manual and the 4PL thread and didn't see anything about it. Maybe they're newb questions, but I'm a newb!

[Charlie-III]

For the servo.... if the trim is "0" and the horn is "centered" as much as possible, you should be able to adjust the draglink (servo to 1st wheel) to get forward steering.


As to the ESC's, maybe try to recalibrate. If still an issue, check drivetrain binding as well as pinion/spur gear mesh. Sounds like "clod stall".

[winnerone23]

I have never tried a full dead centered horn, atleast not that far off.. but if ur trim and sub-trim are zero when you put power to the servo and it goes to center, you should be able to put ur horn on closest to left or right and trim it to center. Then use sub trim to fine tune.

As for ur esc's, I would make sure ur tx is set to neutral an trims are centered. Try recalibrating ur esc's one at a time, or if that's how you did it, try them at the same time..
My HH Br mini's are still a touch off, as where my fxr's.. I adjusted that in my tx tho.

[RcBro]

The guys seemed to hit the servo issue on the head. However a programmer for the servo can really fix your issue.

As for the motors. It sounds like you are saying your front motor starts up before your rear. Are these matched motors or off the shelf motors?

First and foremost you want to ensure your esc's are programmed properly to your radio and both sets of axles have equal drag and same pinions. If the issue still exist you can slightly advance the rear motor to achieve matching startup.

[Trainee]

Thanks all! I didn't even think to adjust the drag link! I'm over thinking this whole project! Although, with as much money as is already tied up into it, I'm going to get the servo programmer if that will do what I want.

I have recalibrated both ESCs twice and still have the same problem, so I'm fairly certain that's not the problem. Both motors are matched Holmes Torquemasters.

I'm running a 12 tooth on the front and 11 on the rear pinion in my Super Bully 65:1 axles. That doesn't seem to be the issue though, because it does the same thing in reverse, only the rear one starts up first. I am checking with no drag on the tires, up on a stand.

Thanks!

[Charlie-III]

When you say "matched", were they ordered as a MOA set?
If not, they both have timing in them, but in a MOA one is advanced & one is retarded. Thus the speed difference in each direction.

[Colgout]

Are the trim and subtrim for channel 2 and 4 (both esc) at zero? you can do a bit of trimming there too I think.

[Trainee]

I did order both motors at the same time, but didn't request a matched pair, so maybe they're not.

I did get the Castle Creations USB link, so I'll have to check the ESCs tonight.

I have another box of goodies coming from CKRC for the end of the week that will have the servo programmer in, along with some new tires and wheels. Going to attempt my own cut and shuts.

[Colgout]

If they are not matched pair. Then you problem will most likely be the timing, set both at zero timing and see if the problem goes away. Then read up info about timing and goes from there.

[Charlie-III]

Originally Posted by Trainee

I did order both motors at the same time, but didn't request a matched pair, so maybe they're not.

Well, for a MOA, you should order as a "matched MOA" set. They will then come labeled "front" & "rear".

So, as I stated before, my bet is the timing is incorrect.