XTM Pro 24.7 2.75HP in a T-Maxx conversion

[steve0357]

The subject title says it all...LOL! I have a T-Maxx, all rebuilt with it with all aluminum, and I had a OS .21 in it, until I burned that sucker up! Anyway, I just got this new XTM motor and wanted to know if anyone has installed this same motor in a T-Maxx? I have all my parts ready, motor, feral that came with the motor, a aluminum flywheel made for a regular t-maxx, clutch and clutch bell. I noticed that this will not all fit, as the shaft looks too long. This motor also has a screw in the tip of the shaft, where the stock t-maxx uses the retaining clip. On my OS .21, I had to add a couple of washers on the shaft, before the feral, because that shaft was too long. What needs to make this new XTM Pro job work with my t-maxx? I hope I don't have to cut that sucker! I see a 1/8th inch gap, between the clutch bell and screw at the end. Also, the screw won't hold the clutch bell in anyway???
Help!

Thanks,
Steve

 

[visioneer_one]

You don't have to cut the shaft.

Do yourself a favor and go to a 1/8-scale spur/CB setup. I have a similar setup on my T-Maxx - the 1/10-scale spurs, clutches and clutchbells simply do not hold up well at these power levels.

Just posted my configuration here : https://www.rcnitrotalk.com/forum/showthread.php?t=24736

The 1/8-scale spur gear is smaller in diameter, so you have to raise the engine slightly. I added eight standard 4mm washers between the engine and the mount; two per screw. As for the fore/aft clutchbell gap IIRC I have two teflon washers between the clutch and CB.

Going on 4 gallons with this setup with no problems.



visioneer_one,
needs practice

 

[steve0357]

Thanks dude! I really appreciate the help! So you recommend that I ditch the stock setup and buy
- RC Solutions 54T spur
- stock Savage 1/8 scale clutchbell (16T)
- XTM 1/8 scale sliding clutch kit (part # C90231)

All of that will fit, without any mods? And, you say that you only needed two washers to fix the gap caused by the the shaft being too long, and you put them between the clutch and clutchbell. What size of washers did you use, cuz the gap is at least 1/8th inch.

How did that fourth tank go? Do you know the weight of your rig? How fast do you think yours is going?

Thanks,

Steve

Being it will take a few days to get all of the 1/8th parts, I would still like to know how to make the stock stuff work with this new motor. When I say stock, I mean it was made to replace the stock t-maxx stuff, but I have the hardened spur gear 72t, hardcore racing aluminum clutch and a stock 16t cb. Adding a couple of washers may help the gap, but what about the screw at the end?? It won't hold the cb on, and I cannot use the original retainer clip.

Thanks!

Steve

 

[visioneer_one]

Thanks dude! I really appreciate the help! So you recommend that I ditch the stock setup and buy
- RC Solutions 54T spur
- stock Savage 1/8 scale clutchbell (16T)
- XTM 1/8 scale sliding clutch kit (part # C90231)

All of that will fit, without any mods? And, you say that you only needed two washers to fix the gap caused by the the shaft being too long, and you put them between the clutch and clutchbell. What size of washers did you use, cuz the gap is at least 1/8th inch.

How did that fourth tank go? Do you know the weight of your rig? How fast do you think yours is going?

Thanks,

Steve

Being it will take a few days to get all of the 1/8th parts, I would still like to know how to make the stock stuff work with this new motor. When I say stock, I mean it was made to replace the stock t-maxx stuff, but I have the hardened spur gear 72t, hardcore racing aluminum clutch and a stock 16t cb. Adding a couple of washers may help the gap, but what about the screw at the end?? It won't hold the cb on, and I cannot use the original retainer clip.

Thanks!

Steve

Mods - I had to mount the engine as far toward the rear of the truck as possible. This meant mounting towards the rear of the engine mounts. I also elected to slide the engine to the right in order to make up for *some* of the height difference between the 1/10 and 1/8 spur gears. If I had a taller motor mount that would work as well.

The 1/8 CB is wider than the 1/10 ones, so that 1/8" gap isn't as big.

Just remembered that the 1/8 CB is *taller* than the 1/10 ones. I had to dremel away a bit of the chassis plate to clear in addition to raising the engine.

I cannot recommend a 72/16 combination. My truck originally had 72/20 gears - way too much torque. It spent much time sliding on its lid until one of the gears in the transmission melted.

At 66/21 and 66/23 the truck was far more driveable.

I'm using all stock gears in the transmission. I did do a FOC, though.

It weighed 11 lbs, 2 oz. I recently switched to Revo wheels and tires, which dropped the weight to 10 lbs, 8 oz.(My mate's Sportmaxx weighs exactly 1 pound less) I've just ordered a lightened chassis. Hope to shave another 1/2 pound off that way.

Speed - my buddy's Revo in stock trim is a hair faster than mine at WOT. Mine accelerates faster, though.

4th *gallon*, not tank. It runs great! Starts quickly and holds a consistent tune. I'm using an one of the ACNCM "enormous heads" - temps rarely get above 220, even when running hard. I keep it a little on the rich side anyway. As an experiment I switched out the stock tank for a 4 oz. Great Planes tank - this has eliminated the trucks tendency to run a little lean when the fuel level is low (and while making right-hand turns)...




visioneer_one,
trying a thing

 

[steve0357]

thanks

Cool, it sounds like I need to get the rest of the parts and upgrade to the 1/8th cb setup. I will do that, but would like to at least break in my motor with the stock stuff. Did you ever have the stock flywheel, clutch, clutchbell on the XTM Pro motor? If so, where did you add the washers and how did you secure the cb, using the screw or what?

When all the 1/8parts come in, I'll upgrade like you did. Yours sounds killer!

Thanks,

Steve

 

[visioneer_one]

Mine is OK. It runs consistently, which is my main concern. Too many weekends wasted waiting for replacement parts to arrive with the previous setup.

I had all the stock stuff on a 'standard' XTM .24. Had a regular threaded shaft.

When that one blew up (!) I replaced it with a Pro (w/ SG shaft) and all the 1/8-scale stuff.

It sounds like your engine has the SG shaft. The only way you'd be able to mount the stock stuff would involve shortening the crankshaft. If you do that you won't be able to easily mount the 1/8 scale items.




visioneer_one,
DNT a Rotostart backplate with no spring.

 

[steve0357]

Thanks again! Do you have any pictures of your setup? I will just order all the 1/8th stuff, and wait to breakin this new motor. I'm ordering the spur gear, clutchbell and clutch. Can I use the stock flywheel? Did you use the feral that came with your new Pro motor? Will I need anything else to put this rig together?

You say that all the 1/8th stuff will fit, so did you use the screw at the end of the shaft to secure the clutchbell?

Sorry, but I'm trying to ensure I understand how all this will go together and be sure I order everything I will need.

Thanks again,

Steve

 

[visioneer_one]

Did you use the feral that came with your new Pro motor?

?? Don't know what you mean.

I don't have any pictures, but I can certainly shoot some tonight.

The XTM sliding clutch kit comes with a flywheel. You can't use the stock flywheel because (a) the sliding clutch shoes don't use pins and (b) the diameter of the 1/8 shoes is nearly th same as that of the stock Maxx 1/10 flywheel.

My clutchbell is secured with the screw at the end of the shaft. I seem to recall there being a slight amount of play. I don't recall whether I needed to add a washer between the CB and the screw.

Pics will tell the tale.





visioneer_one,
Stay tuned

 

[steve0357]

forums sure are cool!

Thanks!

I meant, my new XTM motor came with a feral in the box, to be slid on the shaft before the flywheel. I didn't realize that the new clutchbell kit came with a flywheel, that explains that. Cool that you were able to use the screw to secure the cb. I just need to get these few things, and I should be able to put it all together.

Can't wait to see your pictures of all of this!

Thanks,

Steve

With all the messages, I'm not totally clear as to what gear setup you are currently running. Do you have the 54t spur gear from RC Solutions and the stock 16t cb made for a Savage, meaning you are running a 54 / 16 setup?

Steve

 

[visioneer_one]

Thanks!

I meant, my new XTM motor came with a feral in the box, to be slid on the shaft before the flywheel.

I think you're referring to the brass collet. Yes, you have to use it.

Do you have the 54t spur gear from RC Solutions and the stock 16t cb made for a Savage, meaning you are running a 54 / 16 setup?

I rechecked my invoices - I'm using a 52T RCSolutions spur and a stock 16T Revo CB. The Revo cb uses bigger bearings than the HPI and Ofna clutchbells. (5x11mm vs. 5x10mm)

Bigger bearings are less succeptible to heat stress, and in theory should last longer.

I'll edit my original post.

Pics:

Its no show truck.

Visible here are the XTM flywheel and the clutchbell. As I mentioned I *had* a RRC double-disc slipper setup before I moved to the 1/8 setup. I'd misplaced the stock slipper washer, so I used the RRC one. No slipper pegs or pads; you're supposed to run this completely locked down. You can also see the washers I needed between the mount and engine - these were necessary to close the gap between the cb and spur.

Note the odd angle of the header. The stinger is pressed against the rear edge of the bottom cutout. I need to elongate that cut a bit more, but haven't gotten around to it.

(read: LAZY)

I'm using a Rotostart; you can sort of see the backplate. These work great unless you forget to put in the spring.

The cooling head is an ACNCM Enormous Head. It works a treat as compared with the stock (puny) XTM head. My temps never exceed 220. The two extra vertical fins on top are sacrificial skids they protect the head against damage in rollovers. Inspired by one of my flying/racing mates after he flipped it and slid the thing 30+ yards on its lid on blacktop...

The fins appear to have increased the heat-absorbing ability of the head, as I had to lean the top end a tad more after installing them.

This shows some of the detail of my experimental fuel tank, fuel,line routing, fuel filter placement, etc. The odd angle of the pipe -> header junction is more pronounced here.

I should have pulled off the air filter before taking these pics!



visioneer_one,
giving back

 

[steve0357]

thanks for the pics!

cool pics, and that look like a kick ass setup. Ok, the bad news is I already ordered my stuff, per your other post. So, I have the following on order
- RC Solutions 54T spur
- stock Savage 1/8 scale clutchbell (16T)
- XTM 1/8 scale sliding clutch kit (part # C90231)

This will give me a 54 / 16 ratio. My truck is a bit heavy, 17lbs! Therefore more low end is needed.

Will this stuff work, or do I need to order the 52T spur and change to a Revo cb?

Steve

 

[visioneer_one]

cool pics, and that look like a kick ass setup. Ok, the bad news is I already ordered my stuff, per your other post. So, I have the following on order
- RC Solutions 54T spur
- stock Savage 1/8 scale clutchbell (16T)
- XTM 1/8 scale sliding clutch kit (part # C90231)

This will give me a 54 / 16 ratio. My truck is a bit heavy, 17lbs! Therefore more low end is needed.

Will this stuff work, or do I need to order the 52T spur and change to a Revo cb?

Steve

17 lbs!

Mine weighs 10 lbs 8 oz, and I still think its heavy.

I'm trying to keep it light for racing purposes. Metal parts only where necessary.

Added benefit - I haven't needed to do any major drivetrain upgrades besides a FOC. Stock transmission, stock diffs & drive shafts, etc. The lower ratio lessens the stress on these components as well.

Had RPM shock towers, but pulled them off. The rear RPM tower was bending after jumps and was smashing the shock into the header... replaced the header, then went to aluminum towers.

Aluminum bulks, naturally.

Had RPM arms on it when I originally bought it. After I realized that the seller misrepresented them (they were arms for the original narrow-track T-Maxx) I replaced them with stock Traxxas plastic.

Used to blow caps off the stock shocks after landing jumps. Went to
Integy shocks and springs. Tried RCRaven's 'dual-rate' springs, but found them to be too stiff for my application. The Integy springs are too soft for jumping, but are excellent for racing. I'm going to try some one-hole shock pistons next.

5-cell 1000mAh NIMH rx pack mounted in the stock traxxas battery box. Stock receiver for now - just ordered an XS3.

Stock Traxxas steering servo runs the throttle and brake. Steering is handled by a Hitec HS-5625 MG. This is the second one I've put on here - the first one took a hit (or got wet, or the warranty expired, or something) and locked full-left. Lucky I have a bunch of these sitting around as I've been pulling them from my planes and swapping in HS-5945s.

No reverse servo, obviously. FOC.

Revo wheels and tires. They look cool and are lighter than other all the other low-profile offerings out there. I will be trying a set of S-Maxx wheels and tires soon, though - the Revo tires have soft sidewalls and are getting torn up due to my Hazzard County-style dirt track driving technique

A lightened chassis plate is on the way. I'd really like to get this thing under 10 lbs - I'd then be able to drop to a 17T clutchbell and would still retain the truck's rocketship acceleration.

9 lbs and an 18T CB. Nnnngh!

54/16 = 3.375 ratio. You should be OK. If you feel you need more torque at the low end then try a 15T or 14T clutchbell.

FYI - I don't think that HPI clutchbells come with bearings when ordered as parts. You'll need a pair of 5x10x4mm bearings - the stock Traxxas ones are bigger in diameter (5x11x4mm) and won't fit. I prefer sealed bearings - polyolin is best, but rubber will work fine. Metal shielded ones require maintenance - cleaning, regreasing, etc. Sod that.

What's your purpose for this truck? Racing, jumping, or just general bashing?
I'd also love to know what your shock & spring setup is like.






visioneer_one,
Stunned.

 

[steve0357]

Thanks!

Sorry, my truck is 14lbs, empty tank, still heavy but that was a typo, LOL

So, the stuff I ordered will work, and my gear ratio is ok.....cool.

I just need 5x10x4mm bearings, do you know how many I'll need?

My truck is a project out of control! General bashing, but with a little extra eye candy. I'll post a pic once it's actually running...

Your pictures arse very helpful, thanks again. I hope to put this pos together very soon! I just hope I have everything.

Oh, I have GPM shocks, but I changed the springs to harder chrome springs. I'd have to look up the name, can't remember. They work ok, given my weight.

Steve

 

[visioneer_one]

You'll need two bearings per clutchbell.

I'm down for repairs again... blew out my rear diff. Came off a jump and landed *on* my mate's T-Maxx.

Tip: an overpowered T-Maxx with no rear diff resembles a Honda under hard acceleration...





visioneer_one,
the fronts are smoking!

 

[ToRqUe]

What did u do about the tranny ??? u left it stock ??? And in those pics. how did u mount the engine? I hove those same engine mounts and i can't figure out how the stay in place, but luckely i havent got my new engine yet.

 

[visioneer_one]

Motor mount - there are 4 bolts which hold the mount to the chassis. The engine attaches to the mounts with bolts and locknuts.

Stock transmission with a FOC. I'm keeping the loads is sees down by through the use of higher gear ratios. I originally had the stock 72/20 gears - the truck would flip onto its lid during hard acceleration, and quickly shredded the 2nd speed gear assembly. Replaced it with stock Traxxas parts.

I am on gallon #7 or 8 with this transmission. No problems.

I do have a new one on hand as a spare. Just in case.




visioneer_one,
"If you have spares you'll never need them."

 

[offroader]

i have a xtm 24.7 motor in my tmaxx and it has an unlimited engineering transmission in it and it drives like a dream.

 

[steve0357]

Got pics?

Cool, another 24.7 t-maxx setup. What motor did you get, the regular or the pro? What flywheel and clutch setup did you go with, 1/8th stuff? Do you have any pictures of your rig?

Thanks,

Steve

 

[offroader]

i think its the regular and we used the robinson racing clutch setup ill see if i can get pics

i jux remembered that that motor is putting out 3 hp because it was ported

 

[jon2]

Looks like the pro as the pro has a black case with 2.75 HP and the regular is grey with HP closer to 2.5( I THINK )

Jon