New Losi U4???

[Jimbobjr]

This thread name should be changed to Losi Lasernut. The search engine here will not allow U4.

Anyhow...notice the wear rings on these shafts. Tires are maxing out suspension travel in the cvd/dog bones in the front. Rear is not as bad but the dog bone end has a ring around it.

As I suspected, the tires are too big for the suspension travel. Limiting shock travel with o rings or smaller tires would be an easy fix. Losi needs to redesign the knuckles, axles and cvds to make this a great buggy. Also 17mm hex would be nice.

I'm sure some fancy youtuber will tell you all this but you heard here on the AF first...

 

[Caleb428]

This thread name should be changed to Losi Lasernut. The search engine here will not allow U4.

Anyhow...notice the wear rings on these shafts. Tires are maxing out suspension travel in the cvd/dog bones in the front. Rear is not as bad but the dog bone end has a ring around it.

As I suspected, the tires are too big for the suspension travel. Limiting shock travel with o rings or smaller tires would be an easy fix. Losi needs to redesign the knuckles, axles and cvds to make this a great buggy. Also 17mm hex would be nice.

I'm sure some fancy youtuber will tell you all this but you heard here on the AF first...
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I bought the 17mm conversion parts off m2c for the scte to put on mine. There are some hyrax tires for the UDR that are a half inch smaller but that may not be enough difference. I went with the same size hyrax

 

[Jimbobjr]

Wear on ball as well. Eventually this will fail between the pivot and pin slot.

 

[Jimbobjr]

Without the shocks mounted the chassis has to be forced to touch the floor. That is the point where you can feel the wheels not wanting to turn because of resistance in the cvd. Major design hindrance to a great model...

 

[Caleb428]

I had to shim up my center diff. It was sounding pretty rough when I got on it. Thought I stripped a wheel! No apparent damage done at least and after the shim job it ran fine with no more scary noises.

 

[Jimbobjr]

I had to shim up my center diff. It was sounding pretty rough when I got on it. Thought I stripped a wheel! No apparent damage done at least and after the shim job it ran fine with no more scary noises.

Mine has been great but I can see the cvds are going to be an issue. I don’t want to go with different wheels and tires because I might as well run one of my other buggies. The extra clearance is one of its strong points.

There’s really no way I see to make this size cvd work. You can’t make the ball bigger, the wheel bearing is too small. No way to make more clearance at the shaft, it’s already tiny...

 

[quad_rocket]

there is a good step by step video for a tekno cvd upgrade on yt:

as it is a gift, my preoder is sitting in the garage until next month

probably better this way, let you all figure out the fixes 1st

 

[jym73]

So, finally i was right about tenacity shafts and 4s

 

[quad_rocket]

Not that I know of. I run these and so do a few others in here:

https://www.amainhobbies.com/hot-ra...hub-adapters-4-6mm-offset-hrawh17hs01/p649937

They hold up to 4s all day long and the 2-3 times I ran 6s which was stupidly insane! . You will need a small spacer on the 12mm side to fill some of the deep gap these have, otherwise they wont spin freely, they rub the carrier. I eventually ended up using a spacer washer. They work perfectly though!

can you recommend a 17mm tire/wheel for the lasernut?

 

[gotnitro]

can you recommend a 17mm tire/wheel for the lasernut?

I like the 1/8th scale buggy stuff (currently have black dish PL badlands) on my DB pro, not sure what they would look like on this thing though.

 

[arrma_tigger]

can you recommend a 17mm tire/wheel for the lasernut?

I like the 1/8th scale buggy stuff (currently have black dish PL badlands) on my DB pro, not sure what they would look like on this thing though.

I put the Traxxas TRA6774X wheels on my DB Pro (note: you need a deeper wheel hex).

 

[calebgilmore]

4092 yes but you'll rip out of everything its attached to 1480KV you'd need a UGE pinion to get any type of speed and you'd have to dremel out the mount slot like I had to. 24T pinion is the largest on that mount still having enough material to bolt it up.. I have a 4274 w MAX6 on my Tenacity and had to raise the CD 3mm to fit. Can just clears the chassis. I'm assuming its the same CD and mount. You can see the spacers below. Also, running this motor on 4s without almost locking up the CD made more heat in the CD than the motor and ESC did. Crazy heat! The innards were hot enough to melt the O ring!




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Do you think it's worth upping to the max 8 combo? I know this is a rock racer and not a speed machine but I am fighting putting this setup in there hahahaha. The stock spectrum motor is hitting 170 degrees before I get to lvc so I'm working on a cooling setup for it. I know the hw motor is a higher kv but it's also a little bigger motor so wondered if it would take the strain a little better than the 3668.

 

[gotnitro]

Do you think it's worth upping to the max 8 combo? I know this is a rock racer and not a speed machine but I am fighting putting this setup in there hahahaha. The stock spectrum motor is hitting 170 degrees before I get to lvc so I'm working on a cooling setup for it. I know the hw motor is a higher kv but it's also a little bigger motor so wondered if it would take the strain a little better than the 3668.

170's are just fine for temps. I have a typo in my post, I said max6, meant max8. Max 8 with the 4274 still gets hot too. If you decide to go that route, you will need to shim up the CD case and motor mount about 2-3mm for the can to clear the chassis.

 

[Caleb428]

170's are just fine for temps. I have a typo in my post, I said max6, meant max8. Max 8 with the 4274 still gets hot too. If you decide to go that route, you will need to shim up the CD case and motor mount about 2-3mm for the can to clear the chassis.

Yeah I need to look through my stuff for a good shim other than washers hahaha. I picked up a max8/hobbystar 4074 combo for the price of the max 8 that I may stick in. I was going to use it on a shorty 6s arrma project. I already have a stretched mojave I was calling fat bastard, so if I call it fat boy I need little man hahahahaha

 

[calebgilmore]

170's are just fine for temps. I have a typo in my post, I said max6, meant max8. Max 8 with the 4274 still gets hot too. If you decide to go that route, you will need to shim up the CD case and motor mount about 2-3mm for the can to clear the chassis.

I got a hardened steel spur in, so if I put it on i'll up the diff fluid more too. I had upped it to 100k. it was making a bad noise like the diff was slipping so I took it apart and looked through it, and added a shim to every spot inside. I think I read earlier on here someone had to darn near lock it up to keep the heat down. I have some 20m from my K8 I could put in, or up it to 1 or 2 mil. i'll be able to put a better heat sink on it and a good 40mm fan too

 

[gotnitro]

I got a hardened steel spur in, so if I put it on i'll up the diff fluid more too. I had upped it to 100k. it was making a bad noise like the diff was slipping so I took it apart and looked through it, and added a shim to every spot inside. I think I read earlier on here someone had to darn near lock it up to keep the heat down. I have some 20m from my K8 I could put in, or up it to 1 or 2 mil. i'll be able to put a better heat sink on it and a good 40mm fan too

I had to almost lock my CD up with 20m with that motor ESC combo. The heat it created when it unloaded was unbelievable. I was temping the out drives in the 170's while the motor ESC were still in the 120's. This drive train was not made for that kind of power but I don't care It's fun!

 

[calebgilmore]

I had to almost lock my CD up with 20m with that motor ESC combo. The heat it created when it unloaded was unbelievable. I was temping the out drives in the 170's while the motor ESC were still in the 120's. This drive train was not made for that kind of power but I don't care It's fun!

hahahaha! Good thing it's a steel cup from the factory. What gear do you run? I was guessing with the bigger can it could handle the 14t even though it's a higher kv.

 

[gotnitro]

hahahaha! Good thing it's a steel cup from the factory. What gear do you run? I was guessing with the bigger can it could handle the 14t even though it's a higher kv.

Currently 21T pinion 2200KV. To get a 21T pinion on that mount you will need to dremel the mounting slot. 21T is the largest I can go without dremeling away too much material to be able to tighten the motor down. I might have said 24T pinion before on another post and that is another typo, my bad. Too many projects going on at that time.

What I don't know is the gear ratio on this unit in the F&R diffs. I'm going off of my Tenacity DB pro. The tires on this unit appear to be taller too VS. the stock DB pro tires so if you run those tires with the gearing I'm running assuming the ratio is the same, that might be way too much pinion and that would create heat.

 

[calebgilmore]

Currently 21T pinion 2200KV. To get a 21T pinion on that mount you will need to dremel the mounting slot. 21T is the largest I can go without dremeling away too much material to be able to tighten the motor down. I might have said 24T pinion before on another post and that is another typo, my bad. Too many projects going on at that time.

What I don't know is the gear ratio on this unit in the F&R diffs. I'm going off of my Tenacity DB pro. The tires on this unit appear to be taller too VS. the stock DB pro tires so if you run those tires with the gearing I'm running assuming the ratio is the same, that might be way too much pinion and that would create heat.

Yeah I have been playing with wheel/tire ideas and spent some coin on those aluminum wheels and the hyrax tires so I will probably stay that route on it, so it'll have the same size tires as what is on it now. They will probably weigh a little more. I may stay 12t (think I said 14 earlier, I'm equally messed up hahahaha) and let the added kv boost it a little. I don't want to make it a ripper since that is how all my arrmas are now, but want a little more speed. Jim with Jim's bearings is working on a bearing kit for it, and now I'm trying to catch the tekno drive shafts which are OOS everywhere like most everything else. I snagged a 35kg servo for it, and the metal center braces. i'll do one big teardown when I get all the parts in and do them all at once.

 

[joeing224]

You've got the CVD thing right. On about my 6th run one of the front shafts just snapped at the ball (see pic). The other front shaft is warped.

During my 4th run I lost power to the backend. Opened up the dif and had metal shards everywhere but the ring and pinion looked good... then noticed that the rear pinion bearing was gone. It just came apart and got ground to bits.

All of this is in addition to the tire issue I mentioned earlier in the thread (right rear just keeps spinning the nut off no matter how hard I tighten it down).
This is just like what Greg experienced with it in his RC Driver review

(watch at about the 21:30 mark)


Finally, and this is minor but I'm wondering if it's common, the front screens on the body keep popping out (see pic). Not a big deal, but annoying. Wondering if anyone else has this issue.

I haven't even had this thing out of my backyard grass yet.

I contacted Horizon Hobby over a week ago but so far they haven't responded to me. Worried they aren't going to be standing behind this product.