cbr74
09-19-2009, 10:15 AM
I solved the steering servo problem... for now anyway. I had an extra Hitec HS65HB sitting around so I decided to give a go at fitting it into the F18T.
The stock servo splines are just a bit smaller than the Hitec's. And by a bit I mean.. with a little "persuasion" the stock servo saver will fit a Hitec.
The 65HB comes with a long self tapping collared screw. The shank OD is just a little larger than the brass servo saver sleeve's ID. I don't remember the exact measurement.. but it's around .015" or so. I drilled the brass sleeve out with the closest size drill bit I could find. I think it was about .098".
I used the sleeve and collar screw to force the stock servo saver cam onto the 65. It went on with just a bit of force required. I won't be trying to remove it any time soon. (Tech note: make sure servo is on center and you have the cam properly oriented before you start torquing it down.)
I can't guarantee that forcing the SS to fit won't cause reliability issues later but it's working fine for now.
With the servo saver set at the tension I wanted, I had trouble with the screw loosening so I took it apart and stuck in a washer from an AE diff thrust bearing assembly. (If you're a part number nut, it's ASC21115) That allowed me to tighten the screw all the way down and still get good break away from the saver.
Fitting the servo and saver into the chassis required a little Dremel work. The 65 is a little taller than stock so the top of the saver was hitting the front of the chassis and it didn't quite sit comfortably in the moulded chassis brackets. I used a small cylindrical diamond bur to remove just a bit of material from the chassis in two places so the servo could snuggle in.
There's just enough play in the left side bellcrank pivot to allow the steering assembly to stay in alignment despite the altered saver position.
I'm not terribly fond of the stock mounting system and I'll be on the hunt for some servo mounts that I can use to hard mount the 65 to the chassis. The servo can wiggle around just a little more than I like
Interestingly... the Hitec is reverse polarity from the stock servo and I had to reverse my steering on the transmitter.
Road test: steering feel is much improved, the increased torque is immediately noticeable in the ability to hold high speed corners. It tracks surprisingly true considering the inherent slop of the design.
The carbonite gears are 4 times stronger than nylon so I hope that they withstand track abuse. If not.. I'll put in the metal gear version. I would have used an MG from the start but the HB is what I hand handy. The 65HB in my son's RC18B has held up so far and at just shy of 7 years old, my son isn't the best of drivers.
The stock servo splines are just a bit smaller than the Hitec's. And by a bit I mean.. with a little "persuasion" the stock servo saver will fit a Hitec.
The 65HB comes with a long self tapping collared screw. The shank OD is just a little larger than the brass servo saver sleeve's ID. I don't remember the exact measurement.. but it's around .015" or so. I drilled the brass sleeve out with the closest size drill bit I could find. I think it was about .098".
I used the sleeve and collar screw to force the stock servo saver cam onto the 65. It went on with just a bit of force required. I won't be trying to remove it any time soon. (Tech note: make sure servo is on center and you have the cam properly oriented before you start torquing it down.)
I can't guarantee that forcing the SS to fit won't cause reliability issues later but it's working fine for now.
With the servo saver set at the tension I wanted, I had trouble with the screw loosening so I took it apart and stuck in a washer from an AE diff thrust bearing assembly. (If you're a part number nut, it's ASC21115) That allowed me to tighten the screw all the way down and still get good break away from the saver.
Fitting the servo and saver into the chassis required a little Dremel work. The 65 is a little taller than stock so the top of the saver was hitting the front of the chassis and it didn't quite sit comfortably in the moulded chassis brackets. I used a small cylindrical diamond bur to remove just a bit of material from the chassis in two places so the servo could snuggle in.
There's just enough play in the left side bellcrank pivot to allow the steering assembly to stay in alignment despite the altered saver position.
I'm not terribly fond of the stock mounting system and I'll be on the hunt for some servo mounts that I can use to hard mount the 65 to the chassis. The servo can wiggle around just a little more than I like
Interestingly... the Hitec is reverse polarity from the stock servo and I had to reverse my steering on the transmitter.
Road test: steering feel is much improved, the increased torque is immediately noticeable in the ability to hold high speed corners. It tracks surprisingly true considering the inherent slop of the design.
The carbonite gears are 4 times stronger than nylon so I hope that they withstand track abuse. If not.. I'll put in the metal gear version. I would have used an MG from the start but the HB is what I hand handy. The 65HB in my son's RC18B has held up so far and at just shy of 7 years old, my son isn't the best of drivers.