Futaba FXT build (somewhat)

[Dave145]

Ok since I couldn't sell my FXT I decided to do some work to it. It's far from finished, but it's fun to beat around the yard and down the street. Here's my current (and growing) list of mods that I've done to the truck:
- Proline Masher 2000 monster truck tires on all four corners
- Custom lightweight aluminum axles that I made for my Baja King
- Drive axles from a Tamiya Mud Blaster
- Full steel Ball Bearings
- BELL CRANK STEERING from an RC10GT (really helps with eliminating bumpsteer)
- Shifted battery position to sideways in the chassis to clear recessed servo
- Aluminum shocks on all 4 corners filled with 70wt oil and with light springs for a firm yet bouncy ride
- Adjustable turnbuckles with heavy duty ball ends
- 12mm hex rear wheels from traxxas
- ball bearing front wheels from Tamiya
- Reinforced front chassis with a piece of aluminum

Only issue I'm having with this is electronics. I read somewhere that it was originally powered off a silver stock can motor and a 13 tooth pinion. I do have a silver can motor and a Kyosho mega motor that still somewhat work, but when I put either one of them into the truck the truck hardly moves and they get very hot. My battery is a Duratrax Onyx 5000mah nimh battery, and my esc is a Novak NESC-1X. The smallest 48 pitch pinion i have is around 18 teeth but it will not fit into the transmission (too small to touch the main gear). What motor/gear combo should i use in this truck to giv good acceleration and decent top end without overheating my electronics?

[kaiser]

can't help you on the motor/gearing, but 70wt seems like it's gonna be wayyyyy to stiff. that thing should have 30-40wt in it.

[Coelacanth]

Ok since I couldn't sell my FXT I decided to do some work to it. It's far from finished, but it's fun to beat around the yard and down the street. Here's my current (and growing) list of mods that I've done to the truck:
- BELL CRANK STEERING from an RC10GT (really helps with eliminating bumpsteer)

To reply to this particular upgrade, and having dealt with bump-steer on a few cars already, my experience is that bump-steer is mostly caused by the angle of the tie-rod arms relative to the control arms. If they're not parallel, you can get bump-steer. Upgrading to better-quality steering components, but not addressing the angle issue, will probably not fix bump-steer.

If you're getting bump-steer, read this post of mine, hopefully the pics will demonstrate the problem and how I resolved it.

http://www.rc10talk.com/viewtopic.php?f=30&t=21530&start=108

I agree with kaiser, 70 weight oil would be way too thick. I've used between 25 and 35 weight.

[Dave145]

I need to keep it stiff to go through the tall grass around my house. I'm going to venture a guess that the tall grass and the excessively large tires are what's causing my electronics heat up so quickly . Anyway I had messed around with the bump steer a ton with no results... I like bell cranks anyway. I got tired of the excessively large stock servo saver and breaking servo gears so this works like a simulated servo saver I guess for a lack of better description... I'll have to try to get some pics up after I get home from school in a few hours.

[kaiser]

you get ride height from springs, not oil.

[Dave145]

True. I'm a little short on parts for trucks around my house so I just used what I had for the time being. It actually handles really well both in grass and on pavement for being so stiff. I'll get a video up sometime. It's actually a pretty sweet truck considering I didn't think I'd be able to use it. I'd still trade it for an rc10t any day though...

[Coelacanth]

Grass and bigger tire diameter will definitely cause overheating. Usually if you go with much bigger tires, you downsize your pinion gear accordingly, or vice versa. I did an onroad conversion of an Optima that called for using tires that were about 30% smaller than original, so I put in a bigger pinion gear (with motor and all else being equal) that was 30% bigger, to the nearest tooth number. I think I went from a 10T pinion to a 14T pinion (didn't have a 13T, hehe!).

[Dave145]

Yeah i have an 18 tooth pinion that I've got and thats the smallest size I have, but when I put it on the truck it never contacts the main tranny gear. I've tried several.motors and every mounting hole but nothing fits. That's why i was hoping to know what motor and pinion go in there...

[Lowgear]

An adjustable motor mount might help.

[GoMachV]

Isnt the ftx a metric trans? Metric 48p is different! If you take out a gear let me know. I have 3 nip

[Dave145]

Thanks I'll be sure to do that. I suppose the gear does appear to be sligtly larger pitched than a standard 48 pitch gear. So would any tamiya pinion work for this truck? I know tamiya used the metric 48 pitch at some point if not still currently.those might be easier to get I think. Also what about the diff? Mine is beginning to slip REALLY bad. It sounds like a slipping clutch even though it doesn't even have one so I'd assume it's the diff. I know its a ball diff so I'm guessing it's coming loose?

Also, just how valuable is this thing? Id still like to get rid of it in favor of an rc10t, but i dont want to just give it away. I've had it listed both on here and on craigslist for $100 and I can't get rid of it...

[Lowgear]

I've never tried it but using a Tamiya pinion gear sounds logical.

The problem with selling something like this is you either have to sell it pretty cheaply or wait for the right person to come along.

[Dave145]

Yeah i guess so. I'll have to try the pinion swap tomorrow and see if that works just a thought: would changing the pinion to the correct pitch help keep some heat down? Kind of like when gear mesh is adjusted corectly that heat goes down a bit? Heat build up seems to be my largest problem at the moment.

[Dave145]

Well if anyone wants it it's in the BST area for sale as a parts lot...needs some parts but to would make a great beginner runner. I kind of needed some of the parts for later and I need the money from its sale.