How do I get stable, self-centering steering?

[Chevy-SS]

I've had my T-Maxx for a couple of months and love to bash it, however, the steering leaves much to be desired. I put in the Hitec 645 steering servo, which has plenty of power to turn the wheels even at rest. I have also carefully cleaned and adjusted all front-end components to make sure the entire front end pivots smoothly. My problem is, the truck never seems to track the same way twice. In other words, if you hammer it and try to go in a straight line, you never know which way it will veer off. Sometimes it will go straight, other times it will go to the right or left. You really gotta pay attention and keep correcting the wheel. I wish it would snap to center when I release the steering wheel. Real cars have positive caster built into the front end which will cause the steering wheel to straighten out if you let your hands off the wheel. The more positive caster you have, the more pronounced this effect. However, the T-Maxx has no provisions for caster adjustment and the centering appears to all come from the servo. What magic tricks are you guys working to get these trucks to drive in a straight line?

Thanks for the great forum.

 

[GilBeQuick]

I used to have that problem pretty bad. For me the problem was in the rear wheels. When I'd accellerate hard the rear would squat down enough to put the rear wheels to a tow-out position. What I did was add some rear toe-in and it's tracked fairly straight pretty consistently. Maybe that'll work for you too!

 

[Chevy-SS]

Gil,

thanks for the tip. General wheel alignment would be my primary suspect also. How do you get an accurate four-wheel alignment with everything in synch with the chassis? What alignment equipment are you using? I am using street tires (ProLine Road Rage), so what would you use for settings?

Thanks

 

[GilBeQuick]

I myself am not using a gauge or anything....I just eyeball that biotch untill I think it's right. RPM sells a camber gauge for the big MAXX sized tires and wheels.....I can't seem to find a link right now though....

 

[Domination]

i belive you can get toe and camber gauges to measure each adjustment from RPM if i remember correctly

EDIT- Oh and i belive you can adjust camber by loosening one pillow ball a bit and tightening the other

 

[SkyMaxx]

I think that proper wheel alignment and a rock solid servo is about as good as you are going to get until you experiment with something else. You could probably work something with some springs that recenter the steering linkage when the servo input goes away (kind of like a throttle return spring). You would just have to make certain you balanced the springs so that they keep the wheels centered...then you would need a stronger servo to work against the springs to turn the vehicle.

I personally use a digital servo and trim the truck up for straight running when at WOT. Kind of like an inflight alignement. Since digital servos have excellent re-centering capabilities...all you need is sufficient torque to make it work. I run the HS-5645MG digital high torque servo by HiTec. This sucker cranks out about 160 oz-in of torque and centers beautifully. When I drop the hammer...she goes straight as an arrow.

As for adjusting camber and toe in...that can be best accomplished by using a set of clean rims on all four corners (ie set the camber and toe prior to gluing the tires to the rims). Find a nice flat surface and put the truck on it. The rims should sit flat at all four corners with zero camber. Look at the truck from the top to eyeball adjust the toe. Get it the way you like it...then apply the tires to the rims...and go. That at least, is the way I was taught to do it. No nifty gauges here, but you could always buy them and get the same results.

 

[30%NitroBoy]

Yeah....

Like the above posters have said...A kick ass servo, proper alllignment and camber settings and a nice Bellcrank system would be nice to. I just threw my Stock T-maxx bellcrank and Servo saver in the garbage (that's where it belongs...IMHO).

I also run the 5645-MG Digital servo on my Maxx and It kicks ass.....like Skymaxx said...you drop it and it's ready to go STRAIGHT. I like the Guages from PRM FYI.

Peace

 

[Chevy-SS]

Thanks Gil, Dom, Sky and 30%,

Sounds like the 5645-MG digital servo is the way to go. Will that servo work with my stock T-Maxx transmitter? Also, what about batteries? I heard the digital servos eat up juice fast. However, it would be worth it to have solid steering in the straights.

I ordered a new ProLine bellcrank kit plus the RPM toe-in and camber guages. I also ordered a set of rims which I will use exclusively for alignment purposes.

How about locking up the rear differential? That should really help keep the truck straight. Is that a bad idea?

 

[FastEddy]

It sounds like your servo saver may be its way out the door.

You can change it and see if it helps, or do away with it by installing a ProLine servo saver setup.

-Ed

 

[Losi-HPI]

Can you use digital high torque servos with a non digital transmitter?

 

[wdavidhicks]

As far as alignment goes, if you want to go one step further than just eyeballing it you can measure the distance between the wheels. Once between points forward of the axles. Once between points behind the axles. If the distance forward of the axles is slightly shorter than the distance rear of the axles then you're toed in.

I've actually used this method on a 1:1 car after replacing tie rod ends. I almost didn't bother taking it in for a wheel alignment.

[edited for clarity]

 

[SkyMaxx]

Yes, you can use digital servos with non-digital transmitters.

Yes, you can use digital servos with the stock receiver.

Yes, rechargeables are a good idea when using digital servos, but they are not required. Alkalines or dry cells work just fine.

 

[Chevy-SS]

As always, you guys are full of good ideas. I installed a digital servo, along with Pro-Line bellcrank kit. Plus I bought alignment jigs and a new JR XS3 radio. Truck runs straight as arrow now.

Muchos gracias :mex:

 

[wdavidhicks]

[homer]
"mmmmm..... XS3........."
[/homer]