Proud new owner of a pair of XXT-CR Graphite+

[Miles]

Hi All,

I just purchased a pair Losi XXT-CR G+ off eBay. I think I might have paid a little too much for the condition they are in, but it will be fun restoring them. I found the Losi/AE Parts house, which has some of the old parts and things for restoration. Alot of the screws are rusted, and I want to replace them all with new ones. One of the chassis is broken, so I will be using that as a parts car and optimizing the primary car to have all the best parts.

I have been out of the hobby for about 10+ years now. I used to have a Jrx2 and an RC10T when I raced in middle school. It's been a long while, and I have been doing alot of reading. Vintage really appeals to me because I am familiar with alot of the parts, and was going to restore this XXT-CR as a learning tool to prepare myself for going brushless/lipo. I would LOVE to convert the XXT to brushless/lipo if it's possible?

Are there any good FAQs or tutorials or any reading material that you can all advise I look at? I have been reading what I can, but alot of message boards seem to be full of new-age technologies and lots of 1/8th nitro garble to sift through. Most of the 1/10 off-road message boards don't seem very interested in helping those with outdated product.

Also picked up an XX-CR G+ buggy, and an XXX buggy... but I think I might restore and re-sell those. I might also resell these XXT-CR's, but only if I get a good offer. Anyone have an idea of how much they would be worth as a rolling chassis? Depends on quality I guess.. do vintage radio parts help at all?

Anyways, any info you could pass along, it would be greatly appreciated.. I look forward to seeking help here

I will snap some pix and post them up here in a few...

[Bongo Fury]

I would LOVE to convert the XXT to brushless/lipo if it's possible?

Absolutely it’s possible, I’ve ran my early XX buggy this way before.

Some considerations though, not all of the lipos fit in the chassis, check before buying. Orion 3600, with the fake cell bumps and rounded corners, fits sweet. TrakPower 4900 with much sharper corners does not, it won’t sit flat in the battery area. Height issues can be resolved by using the velcro straps like an early XX instead of the later battery bar, I believe all of the chassis have the velcro slots.

Recommend a "hard case" lipo, required for ROAR racing, helps prevent damage. Lipos do not like being punctured. You MUST have a lipo charger, a balancing lipo charger is best. They are not all that expensive generally. Do not fully discharge a lipo, best to only use 80%. Over charge or under charge is where lipos cause, umm "thermal events" . Most new speed controls have a low voltage cutoff to help prevent over discharge, or there are add on units for older speedos.

The brushless speed controls tend to be larger, can be a snug fit on the chassis, may need to put it on the rear shock tower. Of course they are also heavy, not so good to have the weight up high, but I’m assuming it won’t be used for highly competitive running. Or spring for a Tekin, I think they are small enough to fit on the chassis.

Brushless involves 2 choices, sensored: Novak, LRP, etc, or non sensored, Mamba, Tekin R1, etc. Sensored provides better starting/low speed control. Sensorless is more effective at high speeds. Tekin RS and SpeedPassion GT are hybrid systems, they do both. Motors come both ways too. Sensored motors required for ROAR stock classes.

See how simple this is?

Good Luck! Dave

[Miles]

Thanks for all the info! I learned alot from your post

[Bongo Fury]

You are most welcome, glad to be of some assistance. But fair warning, you are only encouraging my tendency to ramble….

Do not discharge a lipo below 3 volts per cell, 3.2 or so is better/safer. Do not even leave the battery plugged in, many ESCs have a small parasitic drain, could end up over discharging the lipo. Not sure on this, I do not believe that over discharge is a safety issue, but the battery may not recharge.

Over charge, and puncture is where the safety issues are. No more than 4.2v per cell, I think 4.25v is the absolute limit. No averages here, it’s per cell, recommend a balancing charger, it takes care of that. Shorting a battery is always a bad idea, but the immense power of a lipo warrants another reminder. Careful with the wiring.

Charge at the 1C rate, i.e. a 3600mah at 3.6 amps, a 4900 at 4.9 amps. No benefit to hammering it like we always did with the old round things.

If you notice any swelling, carefully and swiftly get the thing away from anything you want to save, get it outside. Salt water and burying it in sand are other approaches if things get any more “exciting” than swelling. I forget the details, but common fire extinguishers are a no no, it takes a special expensive kind.

That said, don’t be scared, just be aware and treat it correctly.

They hold charge well, no problem to charge say the night before running. Long term storage a 50-80% charge state is recommended, 3.8v per cell is frequently mentioned. No need to cycle it, little/no benefit. But you can recharge right after running, one of the best features, very cool.

Oh, and on the brushless motors, if you get a stock 17.5 (stock) or 13.5 (both sensored), be prepared to buy some frickin’ humongous pinions if you want any speed. Today I ran 28/76 pinion/spur with a 17.5 on a XXX-T CR (2.43 tranny), possibly could have went a little higher. Used 35/76 on the buggy with the 17.5, 29/76 with a 13.5 some, ditto. All on an indoor hard packed offroad track with lots of big jumps. Just watch your motor and speedo temps, ~140F is safe, 160 not too bad, above 180 well you were just asking for it.

Novak’s gearing guidelines, a safe starting point:

http://teamnovak.com/tech_info/brushless/br_gearing.html

Cheers, Dave