Losi Baja Rey 1/10th 4WD RTR desert truck

[Orange peel]

I know. Everyone asks what it is and thinks its a 2wd because it's tracking sideways most of the time lol! But like you said competition is getting stiffer so I've let mine sit on the shelf. Glad you're keeping yours racing, good truck I think and feels good when it places well.

 

[TheLetterJ]

FedEx just dropped off my new battery, an SMC 7200mah 90c 3s hard case. Fits like a glove with the battery box spacer removed. I don't see myself ever running through that in one shot, but I figured I'd go big so I can get 2-3 runs before needing to charge when we're out away from home... heck, I could probably use it to charge my little crawler batteries!

We're headed out to the desert this coming weekend so I'll get to run the Baja Rey on its home turf.

 

[skeeler]

@TheLetterJ

SMC lists this battery as 139x48x37 mm. Would you say that's the largest battery that will fit? This is a useful data point.

 

[TheLetterJ]

Absolutely the largest I could see fitting in there. It doesn't rattle in any direction, the little foam pad on the battery door has to be compressed pretty good to even get the door shut.

The wires are also 10 gauge which is one heck of a tight fit in an EC3 connector, but I got it soldered on there! It would have been nice if this truck used the more appropriately sized EC5 instead, but now that I've got this monster in there, I doubt I'll need a bunch of batteries.

 

[skeeler]

Thanks. I agree; EC5 would be much better.

 

[TheLetterJ]

My wife asked how long the truck would run with the new battery and I said "it will probably break something before I go through the pack." Well, I was right. Angry, crunchy noises in the front diff. I had replaced the pinion bearings already, then replaced the pinion bearings and the cases, but this is the first time I heard it make crunchy sounds. The pinion bearings don't even feel bad, but the bearing fit in the cases is loose again. The ring and pinion aren't stripped, but I can feel some sharp edges so it may be best to replace them this time. It feels smooth, but I still need to open the diff to inspect the spider gears too.

The rear diff with the Metal Concepts 3rd member is holding up like a champ, now we really need a billet front diff housing to match! I sent an email to Metal Concepts, but who else might be up to the job?

 

[CM9000]

are you running 3s?

 

[JDM74]

are you running 3s?

Yes he is.

 

[CM9000]

that's his problem right there, 3s will just destroy crap on this truck. ive replaced my bearings once in the front and the back from when I first bought it last july. ive put.. eh 40+ packs through it on 2s. but im also running a 12t pinion.

 

[Expo_cam]

These should be pretty rad, he said the uppers will also be made soon. Would look amazing with the trailing arms, and rearend also

Sent from my SM-N920T using Tapatalk

 

[mewalsh100]

Baja Rey manual seems to jive with "Table 2" on the HW card. For now I just made a couple changes the "old fashioned way" and reduced the timing from 18.75 down to 3.75 as well as reducing start mode to level 3 and turning reverse up to 50%... I think I might put that back to 25%.

Were you able to confirm that it was Table 2? I finally got a chance to plug mine in and play around with it for a bit. It seems like table 2, but it didn't seem to change my brake force under item 5 on table 2?

[/QUOTE]

 

[TheLetterJ]

that's his problem right there, 3s will just destroy crap on this truck. ive replaced my bearings once in the front and the back from when I first bought it last july. ive put.. eh 40+ packs through it on 2s. but im also running a 12t pinion.

Yes, I've been running 3s exclusively, but I won't say that's a "problem." I've been running an average of 1 3200mah pack through it a day (some days I've run 3-4 packs, others not at all) since I got the truck 6 weeks or so ago, so similar run time to what you've had. Yesterday was my first outing with the 7200mah pack, I haven't charged it to see exactly how much I used, but I'd imagine I ran a bit over 5000mah before I heard the crunching.

I'm not at all complaining about it, if I wanted it to never break, I could always switch to NiMh, or buy a Slash! This truck has been reasonably reliable, power and usage considered. Just like with our crawlers, if something breaks, we want to upgrade so that we can continue driving it in the same manner but more reliably.

I switched to the 10T pinion after the first couple packs (truck was WAY too fast for the space I have available) so it definitely has much more punch off the bottom, which certainly contributes to the diff housings deforming. I'd rather pay for an aluminum housing than cut the power back.

 

[TheLetterJ]

mewalsh100: Yes, the blue table 2 sticker is the correct one for this truck, and as you've already found out, the program card gets plugged into the fan port as JDM74 already said.

Are you trying to get more braking force? It seems like 75% max brake force is enough to make the truck pick up the back wheels on a hard surface, but not enough to send it into a front flip. I've yet to try 100% braking force to see if it might actually be enough to make it cartwheel. I'm wondering if bumping up item #7 "initial brake force" to 20% (or even 40%) might be the better answer instead of increasing the max brake force? With the center diff completely open, you'll lose a bit of front braking when the back tires get light or come off the ground since it will allow the rear wheels to lock (which won't do anything to help slow you down if they have no traction) and the front will effectively "diff out." I did notice slightly better braking once I locked the center diff, without making any ESC changes, but that has its own handling quirks.

 

[CM9000]

Yes, I've been running 3s exclusively, but I won't say that's a "problem." I've been running an average of 1 3200mah pack through it a day (some days I've run 3-4 packs, others not at all) since I got the truck 6 weeks or so ago, so similar run time to what you've had. Yesterday was my first outing with the 7200mah pack, I haven't charged it to see exactly how much I used, but I'd imagine I ran a bit over 5000mah before I heard the crunching.

I'm not at all complaining about it, if I wanted it to never break, I could always switch to NiMh, or buy a Slash! This truck has been reasonably reliable, power and usage considered. Just like with our crawlers, if something breaks, we want to upgrade so that we can continue driving it in the same manner but more reliably.

I switched to the 10T pinion after the first couple packs (truck was WAY too fast for the space I have available) so it definitely has much more punch off the bottom, which certainly contributes to the diff housings deforming. I'd rather pay for an aluminum housing than cut the power back.

when I say 40 plus packs.. I mean from 8.4 volts straight down to 7.6 volts in 7 min mains, down to roughly 7.8 volts in 5 minute qualifiers. that's only 8 points race days. I didn't include the 3 fun runs, the great lakes showdown 3 day event, or they days I take it to the skatepark.

I have to replace my chassis plate before I have to bearings, if that means anything to you. 3s in this truck will break stuff. 2s is moderate and raceable and bashable. but I guess that's just my opinion to some and not facts. ive probably put 80 cycles or more through this truck on a 7200mah pack.

to say 3s isn't the problem.. is like saying ice cream doesn't melt in your mouth.

not trying to bust your balls, just trying to help you save a little downtime and money while still being able to have fun with the truck.

 

[TheLetterJ]

I get it. I'm not trying to one up anybody here. But I think you're missing my point.

3s isn't a problem FOR ME, differential housings distorting and taking out tiny bearings (and gears if it's not caught in time) is the problem. Does running 3s make the problem surface faster? Without a doubt. But let's be honest, even stock brushed/nimh rc's use bigger pinion bearings.

Plenty of people running 2s have already had the same problem too. So to make that part of the car reliable we can either fix the real problem (with a sturdier housing and bigger bearings like MC has done for the rear axle), or reduce power to the point of not being fun anymore. I'm not saying 2s wouldn't be fun, I'm saying it's gonna take much less power, like NiMh, to be able to truly call that part reliable. I'd just prefer to go with the former.

Maybe if a solution to this problem is found, I'll throw a 4s in there to find the next weak link in the drivetrain for the greater good? Nothing wrong with trying to find improvements, even if not everyone feels the need.

When my very mild SBC ate it's 8.5" 10 bolt rear axle I didn't choose to reduce power, I built a stronger 8.875" 12bolt. When I tore a 1350 yoke off of that and busted a chromoly shaft, I built a 10.5" 14 bolt. Problem finally solved. Imagine if I just kept putting more 10 bolt in instead of fixing the problem. Much the same scenario as what I'm working with here. (BTW, the tranny was definitely the next weak link!)

For now, I'll order stock replacements to get the truck going again, turn the punch mode to its lowest setting in an effort to minimize shock, and drive the thing. Maybe I'll try a hose clamp around the front pinion support. No sleep lost. I'll ask Michael at Metal Concepts if he needs a housing to use for prototyping.

 

[SSD]

We will have a HD third member out in a couple of weeks...

 

[TheLetterJ]

That's good to hear. Any plans for a front housing?

I measured the gap that had opened up at the outer pinion bearing of the front housing at 0.009" with a feeler gauge. Both pinion bearings are still in good shape. The inner pinion bearing seems to be fairly well supported having a pinch bolt in the housing above and below, but the outer bearing is just hangin' out in space, not a good thing when the bearing sits dead center of a seam. I know I said I might try wrapping a hose clamp around the outer pinion support, but now that I look at it, that's not really a possibility... any other ideas the hold it together tightly?

 

[skeeler]

That's good to hear. Any plans for a front housing?

Agreed. Sounds like front diff housing would be popular.

 

[mewalsh100]

mewalsh100: Yes, the blue table 2 sticker is the correct one for this truck, and as you've already found out, the program card gets plugged into the fan port as JDM74 already said.

Are you trying to get more braking force? It seems like 75% max brake force is enough to make the truck pick up the back wheels on a hard surface, but not enough to send it into a front flip. I've yet to try 100% braking force to see if it might actually be enough to make it cartwheel. I'm wondering if bumping up item #7 "initial brake force" to 20% (or even 40%) might be the better answer instead of increasing the max brake force? With the center diff completely open, you'll lose a bit of front braking when the back tires get light or come off the ground since it will allow the rear wheels to lock (which won't do anything to help slow you down if they have no traction) and the front will effectively "diff out." I did notice slightly better braking once I locked the center diff, without making any ESC changes, but that has its own handling quirks.

Actually, I was just playing around with a bunch of the settings to get a feel for how much change they provide. I did stick at 75% brake force. (I may decrease it from here even depending on track/course conditions). Any more and the truck will go ass over tea kettle with good traction. In addition to that, I ran 6 packs through today on my little side and back yard "test course". (3 2s packs and 3 3s packs.) This thing is a beast on 3s! Track has some small jumps, corduroy, and tight turns. I added some toe out to the front end (TLR adjustable turnbuckles) which definitely increased drive ability and keeping this thing straight - sort of:shock:. I kept 35W in both the front and rear shocks, but I did locate the rear shock mounts to the setting further back. (on the new Losi aluminum lowers) It sacrifices a tiny bit of travel, but the truck seems more planted in the corners and definitely scoots out of them quicker. I was a little underwhelmed with the 10T pinion on the 2s, but since I knew I was going to be running the 3s packs I figured better safe than sorry. Motor temps were right around 122 degrees pretty consistently. (Yeah racing fan on) I also played around a lot with the AVC function on the new Spectrum DX4C transmitter. I basically shut off throttle and vastly minimized steering. This truck likes to be steered with the throttle so...... Anyway, I'm pleased overall with the changes so far. Waiting for our local track to dry up so I can really suss things out. As much as the rear shock positioning helped on my little track, I think I'll have to move them back for the local course here. Much bigger jumps and woops that the increased travel will be required on.

 

[CM9000]

scored 6th in points with a solid axle truck... the f am I doing? thought I got 4th because of someone not showing up and I beat the two people ahead of me in points... place 4th this past raced.

and yes, I will argue 3s is the problem. ive only had to replace bearings once.