LOSI LST XXL Conversion ideas - Page 17 - RC-Monster Forums

mistercrash · 06.20.2010, 09:38 PM

Today's damage

One broken wheel (it was cracked before so no big loss)

And one pebble wedged in the wrong place. I was wondering why I lost steering all of a sudden.

pinkpanda3310 · 06.20.2010, 10:11 PM

So you lost steering but kept the throttle on and that's how you broke the wheel. And you call youself mistercrash, lol.

mistercrash · 06.21.2010, 09:03 AM

Not really, the wheel broke like that from hitting a rock on the construction site we were running on. I kept on going. The pebble incident happened some time later on the second set of lipos.

mistercrash · 12:49 PM

Hmmm... After a 40 minute run with my 3S 5800 mah lipos, the temps were lipos: 120 F, ESC: 135 F and motor: 200 F

I was not happy that my beloved NEU 1521 got up to 200 degrees. I am presently geared with a 54 tooth spur and a 23 tooth RCM pinion. I was running MT Crime Fighters which are a lot smaller then the Losi LST wheels and tires. I also noticed after the run that there was a rock wedged between the rear tranny output CVD and the chassis top plate. This might have contributed to something but I think that I'm still geared too low. I can't go smaller on the spur so I just ordered three new RCM pinions. 24, 25 and 26 tooth. I hope I can find the correct gearing with those. It was an extremely hot and humid day with no wind and I ran the truck very hard on sand and gravel jumping a 5 foot gravel hill that was dumped in an empty lot yesterday near my house. I ran non stop for the whole lipo cycle, maybe I should give this truck a break from time to time

suicideneil · 06.23.2010, 01:46 PM

40 minutes straight? hmm...

I tend to check temps fairly regulalylllyylyylyy, allowing a 10 minute cooling down break as required- I know some guys prefer to just run & run, but sometimes the truck doesnt

mistercrash · 02:07 PM

I am not sure what to think of what you just said thererererere. Stop frequently to check temps and allow to cool if needed? I should be able to run this truck as I please for a whole lipo cycle and once it hits LVC, THEN I allow everything to cool before I put a fresh set of lipos in and keep going. With the outside temperature being what it was at the time and running non stop for 40 minutes, I expected the MMM to have the fan on and the lipos to be close or at 120 degrees. But I would have been happier if the motor showed 170 or 175, not 200. I'll try a larger pinion next time (gotta wait 'till they get here) and see if the motor temp goes down a bit. I hope it does.

Thanks Neil

mistercrash · 06.27.2010, 02:47 PM

I updated my MMM with new settings, it was at 10° timing so I went to 0° and brought down the braking from 40% to 30%. The motor temp went down a bit from 200 to 190. ESC was at 135 and lipos at 118. It's a little better but not quite enough. The weather was pretty much the same as the other day, very hot and humid and I was running the same lipos, bashing in the same spot and doing the same things with the truck which is run it fast and jump it high. I'm thinking a motor heat sink would help.

Anyone know where I can find a good heat sink for a 40 mm motor?

How in the world did a rock get in there,

and when I yanked it out, I noticed my first breakage of a suspension component.

mistercrash · 07.05.2010, 07:52 PM

I received the Losi motor heat sink today. It is very well made and has very large fins. It fits perfectly in my converted LST XXL and doesn't interfere with anything. What a difference this thing makes in motor temp. On the first test run on 4S, the motor ran at only 125 degrees. Tomorrow I will charge a couple sets of 3S and test running on 6S. Right now I am very pleased with this heat sink.

mistercrash · 07.06.2010, 09:52 PM

I received my pinions from Mike last week. Thanks Mike. So I tried going up one tooth on the pinion. 54 spur and 24 pinion with Crime Fighters MT tires on MT wheels. I had my new heat sink on the motor and went out on 6S. Outside temp was 91 F with the sun shinning, with the humidex, it felt more like 105 F. It was really hot in my garage and the temp of the motor before starting was already at close to 100 degrees. I ran hard for 20 minutes, non stop. Climbing, jumping, speed runs on asphalt, grass and gravel, donuts. Had a few tumbles, broke a front suspension arm again and the doohicky in a rear CVD that you put the grub screw in to hold the pin.

Temps were:

Motor: 170
ESC: 140
Lipos: 145

front and rear diffs: 140
Center diff: 170 at the tranny casing. So the CD inside might have been close to 200.

The heat sink really helps but I think I need to go back to the 23 T pinion to bring the lipo temp down. The front tires were balloning like crazy so I will take out the CD as I suspect that when it gets too hot, too much power is wasted on the front wheels making the motor rev needlessly. This truck is so tough. My old E-Revo would have been in pieces if I subjected it to what I do to this XXL.

nuz69 · 07.07.2010, 03:44 AM

Hello, this kind of temp is the CD is normal, I hit the same in my truggy with a 1520/1Y. Are your wheels really balanced ? I had temp issue with non balanced wheels, which is always the case when you use monster truck wheels... Try maybe to do some air flow in the body, that helps a lot...
The hot batteries means that you are pumping of lot of amps, can you reming us your mph gearing setup, the weight of the truck and the type of batteries ? Maybe something is wrong in the transmission, and that would explain this temps.

mistercrash · 11:37 AM

I had these Proline 40 series Mashers mounted on Axial 8 spoke over sized chrome wheels. The chrome was flaking off and it just looked ugly. I dipped the wheels and tires in Acetone for 36 hours and ended up with very clean wheels and tires but it ruined the foam insert. I took the chrome off the wheels with Easy-Off oven cleaner and then dyed them with black Ryt dye. I purchased Racers Edge two stage 40 series foam inserts and put an extra layer of foam around the middle part. This over stuffs the Proline Mashers, making them firmer and gives a nice crown that I like. I like the 40 series Mashers on the LST because I think they are the perfect size for the truck. The same width as the Losi 420 series ATX but a tad smaller on the diameter.

mistercrash · 11:00 PM

Has anyone ever thought of getting rid of the E clips on the LST's suspension? I did some web searching and it looks like the 4 mm hinge pins with E clips could be replaced with M4 X 0.7 X 55 mm 12.9 grade socket head cap screws. These screws don't have threads all the way. only at the end, leaving a long shoulder before the screw head (not sure but it looks like around 40 mm long) that could act as the hinge pin. Put an M4 washer on the screw, slide the screw in, put a second washer and a lock nut and cut the excess threads with a dremel. No more E clips. I also thought about using the shock shafts but the screws would be easier. I know there's other Losi RCs that use threaded outer hinge pins but I'm not sure of their dimensions and I won't pay 5 bucks plus shipping just for two.

Here's a link to the screw I'm thinking about.
http://www.fastenal.com/web/products...5PF0000&ucst=t

The image in the link is not representative of the real screw which does not have threads all the way up to the head. I found a CAD drawing of the 60 mm and 50 mm screws but I couldn't find a drawing of the 55 mm screw. The 60 mm screw has a shoulder of 46 mm, the 50 mm screw has a shoulder of 36 mm. A little more than 38 mm is needed so the 55 mm screw with an estimated shoulder of 40/41 mm would be perfect.

JThiessen · 07.17.2010, 11:56 PM

JAILBIRD found these http://www.teamstrc.com/ebproductdet...mainid=3&id=68
You might get away with sckt hd cap screws if you are still running all plastic parts there, but the finish on them is not meant to be used as a bearing surface. Thread length on them should be around 14mm - so your guess of 40mm was close. Probably function ok though. Use a nylock nut.

mistercrash · 10:29 AM

Someone on the LST forums gave me the link to the ST Racing threaded hinge pins also. Like I said to him, $20 plus shipping for 8 bugs me a bit. They look good though but for $0.65 for a screw and the Nylock nut, I can have the same thing, maybe better for so much less. All it needs is a little effort on my part to make the surface of the shoulder smooth. I'll just chuck the screw in the drill press on high speed and use fine sand paper to smooth out the shoulder. It'll work very well I'm sure of it.

mistercrash · 07.21.2010, 10:36 AM

A little while ago, the pinion and internal gears stripped in my rear diff. I repaired it thinking it was just what happens when you bash too hard. A couple days later, I blow the internal gears of my front diff and a pinion in the rear diff. I thought I was just unlucky. Yesterday, the internal gears of the front and rear diffs blew. This is a problem. I can explain pinions stripping if I didn't shim correctly but internal gears, there's not much I can do in there. I use the Losi HD diff cases so I'm baffled. What can cause the innerds of my diffs to strip so often?