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So I have a Hitec 645MG servo on the way along with a castle sidewinder & 3800kv motor . Just wondering if I should also be thinking about replacing the old original steering bellcrank with something different than the factory plastic parts...? I see here is a FT part for around $25. Any other options I should consider?

You mean on the T4? There should be a factory team part, which is likely better (less flex)

Yes sorry by FT I meant factory team. Some times those "team parts" are more for show than for go, so I was just curious about peoples' experience.

stock bell cranks are fine. it took me years to break a stocker, replaced with a stocker.

Good to hear thats not one of the weak points. I figure as soon as I bolt in some brushless 3800kv power and a twitchy 133 oz-in torque servo, I'm gonna start breaking stuff…

But unlike some of the other cars we have, I think the T4 deserves the investment in upgraded parts because of how fun it is to drive.

In my experience, you'll need to worry more about the 645mg frying than any other steering components breaking. Be sure to set your endpoints well, and don't be surprised if your steering locks up and the servo starts smoking.
I have two 625's (one of which was converted to a 645). After sending them back to hitec about four times each to have fried motors replaced, I finally gave up. Based on this experience I'd never get another cheap Hitec servo, though my more expensive Hitec (a 7965) has been great.
For the price of the 645, I recommend the Solar D771. They're faster, torquier, digital, coreless, with full metal gears, and much more reliable. They even have aluminum cases! I've had two for a while, both are still going strong.

85Edinger wrote:In my experience, you'll need to worry more about the 645mg frying than any other steering components breaking. Be sure to set your endpoints well, and don't be surprised if your steering locks up and the servo starts smoking.
I have two 625's (one of which was converted to a 645). After sending them back to hitec about four times each to have fried motors replaced, I finally gave up.

Really. That's disappointing to hear. Based on what I've read they seem to have a very good reputation (albeit slow at 0.20 sec compared to 0.08 for a Savox 1258). But I just wasn't quite ready to drop $80 on a servo just yet. Hopefully I don't learn the hard way… I'll post back with pictures and results as I put things together.

-Brent

So I just finished bolting in a Castle 3800 and Sidewinder SCT combo, along with a Hitec servo. It took a bit of creative dremeling to get the servo to fit properly and a few shims here and there, but I tested it on the old brushed motor and it was solid and centered.

Next I bolted in the Castle system and despite it getting a bit dark, I couldn't wait to go outside and test it. After a couple of speed runs and wheelies, I decided to do some slow-speed circles just to warm things up a bit. Well, the steering wheel on my radio got stuck (it had a piece of zip tie stuck in it!) and I slammed into a curb at about 1/3 throttle…

Looks like I'm in the market for a new chassis pan and Top Plate...

Aww, bummer! It happens, though.

I figure as soon as I bolt in some brushless 3800kv power and a twitchy 133 oz-in torque servo, I'm gonna start breaking stuff…

On servos, don't worry about your bell cranks. That's what servo savers are for (works both ways). I'm running a Savox SC0251MG in one of my 10GTs (that's a 222 oz oversized servo) and Kyosho KS200s (200 oz) in two of my buggies and my 10T.

As for power, the castle 3800 isn't over the top, especially not on 2S. About equivalent to the Hobbywing 10 turn I'm running in my 10T, which has only caused one stripped idler gear. I run that truck on a 2S 40-80C 8,000 mAh pack with the punch turned all the way up, and mostly on a high grip clay indoor track.

Older pic, with outdoor tires on and the now-dead S1903MG servo:



Really, AE stuff can handle quite a bit of power. My carbon fiber "destroyer" buggy still has the original, completely stock stealth. It went brushless early last year, and has been getting hammered with 3S to the 3,300 KV Venom motor with 24/81 gearing. It's a tad heavy at 4 lbs, on account of the 4mm thick chassis, custom 7075-T6 arm mounts, rear carriers and super-duty nose brace. Also way overpowered, and the diff and spur are both pretty tight to effectively transmit that power. I tore up a set of universal axles after about 20 packs, but the trans is hanging in there just fine.

I run a T4.1 that's been converted to a JConcepts J82. It's my beater car that goes with me to the desert and sand dunes. It's a blast with the Castle 3800. It's plenty fast geared 21/81 and runs nice and cool. I'm pretty impressed you managed to break the chassis. Mine has been run very hard and the only thing I seem to break, is the rear T-plate. When you get it fixed, have fun...it's a great setup.

Thanks guys! I already ordered a top plate and chassis along with a new steering bellcrank. $36!and I should be back in business in a week... The broken parts seemed very brittle wondering if maybe they were just old or if maybe it was a carbon composite chassis...?

So how do you like the brushless setup now?

sbsyncro wrote:Really. That's disappointing to hear. Based on what I've read they seem to have a very good reputation (albeit slow at 0.20 sec compared to 0.08 for a Savox 1258). But I just wasn't quite ready to drop $80 on a servo just yet. Hopefully I don't learn the hard way…

I wouldn't worry about the servo, I ran a 625 in my touring car for several years until it stopped working. Took it apart and it had run so long the motor brushes had worn right down so they were no longer reaching the armature.

They do have a good reputation, I probably just got unlucky.

So I moved everything over to the new chassis and top plate today and fiddled with the steering to get it set up properly. I didn't pay enough attention before - the PO had the tie rods all jacked up so that it would only go full lock in one direction (I had just duplicated everything when I put the new servo in). I reset the servo horn position, installed a new servo link with new ball cups, and re-centered everything. Now it turns lock-to-lock and will do nice tight little circles. I had to use the servo horn that came with the servo, so some jerry-rigging was required. (Anyone have a spare "H" servo horn they'd be willing to part with?). Once I did that I was able to set up the end points to 65% on one side and 70% on the other, and needed a bit of trim to get it to run straight (I have the servo link as short as I could get it, but its still a bit long).

I've noticed that this car does not aggressively re-center its steering - it tends to want to hold whatever line you set it to, which I think I might grow to like - it just requires a different driving style. The servo itself snaps back to center when I release the steering wheel, its just that the wheels seem to want to track in whatever direction they are going until they are aggressively repositioned. I've set the camber to about 2 degrees and eyeballed the toe-in at maybe 2 degrees. Everything in the steering seems to be free and loose.

I'm running the 87T spur that was on the car when I got it and a 16t pinion, with the slipper clutch adjusted three turns down from the nut just touching the spring. Definitely not scary fast, but with a 14:1 final drive ratio, I'm being pretty conservative. I'm thinking about stepping up to a 72t or 75t spur - those seem like more popular choices. Does one need to buy those clutch pads separately for each spur gear?

Lots of questions, I know….

Bottom line, though… this car is a BLAST to drive compared to the 3 Traxxas cars we have (Slash 2wd, Rustler VXL, Stampede 2WD). By comparison, the T4 can do sudden sharp turns on the pavement without flipping - it seems to have such a low center of gravity and supple suspension that soaks up bumps without becoming jouncy or unsettled. I can't wait to get some track tires for it and bring it out to the track!