Senton Shock absorbing front bumper for the arrma Senton!

[NewSensei]

So far in the month or so I've had my Senton I have only broken the front bumper but I have had the aluminum plate that holds the A arm pins fall out a couple of times. Though, I think that was due to the poor bodge job I did on the bumper after the first break flexing the skid plate. That said, I've upgraded to brushless and 3s on occasion (have two 3s and 5 2s) and so far it seems to be holding up well, I did buy and install the center drive shaft support (haven't screwed it in yet since I need to drill a hole) but other than that and new tires it is stock. No leeks in the shocks yet and no broken anything else except the upper support of the front bumper. It really doesn't take much to break that...

Has anyone tried making a spring loaded replacement for the upper support? I've seen the after market bumper but have also heard it doesn't fair much better than the stock one for more than twice the cost... I'm thinking of making an upper support that is spring loaded (or maybe even with small shock absorbers) but before I reinvent the wheel I was curious if anyone else had done this sort of thing and what commonly breaks on the mega/BLX other than the bumper. I may just be lucky, had a few bad landings but those were only after a 6 to 10 foot jump so I haven't REALLY ragged it out but I'm thinking of getting some spare parts to have on hand as well as modifying the front bumper to be a little stronger...

 

[Camaroboy383]

Sorry I'm not sure on the breakages of those vehicles.. if it's a mega I know it has the same chassis so you could use a typhon buggy bumper from tbone.. but will have to deal with the retainer fix.. but any 3s and 4s bumper will fit.. outcast, kraton, typhon, granite.....

Also as a side note, there is no hole for the center shaft bearing carrier.. the screw enters the carrier from the top, under the bearing, the screw spreads the tabs and then wedges itself into the honeycomb.. don't drill a hole in the chassis...

 

[Cheapbastard]

I broke the skid plate and bumper on my Senton. The stock bumper is not very sturdy it's a common break and seem to be in the same spot also. When mine broke I almost lost the hinge brace didn't realize the skid plate was broke. I made kind of my own fix. I drilled two holes through the skid plate bumper mount into the hinge pin brace and into the chassis then screwed 2 3mm bolts in. I also busted one of the parts on the front of the bumper that most commonly breaks. I took it off and drilled a hole so I could put in what amounts to a threaded rod like a turnbuckle then drilled a hole in the other part of the bumper and threaded it in to bumper. I drilled it off center and could have done a better job but it works. Been running with a broke skid plate and threaded rod piece bumper now run into things and haven't broken it again. Was going to the T-bone route but don't think I will now. It's not really a fix but has worked for me.

 

[NewSensei]

Sorry I'm not sure on the breakages of those vehicles.. if it's a mega I know it has the same chassis so you could use a typhon buggy bumper from tbone.. but will have to deal with the retainer fix.. but any 3s and 4s bumper will fit.. outcast, kraton, typhon, granite.....

Also as a side note, there is no hole for the center shaft bearing carrier.. the screw enters the carrier from the top, under the bearing, the screw spreads the tabs and then wedges itself into the honeycomb.. don't drill a hole in the chassis...

Thank you for letting me know about the bearing carrier, I might never have noticed

I broke the skid plate and bumper on my Senton. The stock bumper is not very sturdy it's a common break and seem to be in the same spot also. When mine broke I almost lost the hinge brace didn't realize the skid plate was broke. I made kind of my own fix. I drilled two holes through the skid plate bumper mount into the hinge pin brace and into the chassis then screwed 2 3mm bolts in. I also busted one of the parts on the front of the bumper that most commonly breaks. I took it off and drilled a hole so I could put in what amounts to a threaded rod like a turnbuckle then drilled a hole in the other part of the bumper and threaded it in to bumper. I drilled it off center and could have done a better job but it works. Been running with a broke skid plate and threaded rod piece bumper now run into things and haven't broken it again. Was going to the T-bone route but don't think I will now. It's not really a fix but has worked for me.

This is really starting to seem like a manufacturing defect, all of the bumper breaks have been the exact same spot. I'd tried unthreaded steel rods in the middle but it did eventually pull apart. I might try threaded and see what that does till I can come up with a solution for taking hard hits and it not mattering...for the bumper at least

Arrma needs to be putting better bumpers in, I literally broke the last one not even doing 10mph and bumping the curb (not even a hard hit)!

 

[NewSensei]

So, I went and bodged together an actual shock absorbing bumper, I'd love to see something like this made available stock but not likely...that said, really wasn't that hard outside of getting the metal sorted since all I had was a thin gauge aluminum sheet laying about. Still, worked out pretty good so far, might redo with thicker aluminum or possibly 3d print (if I ever buy one) but it is pretty solid so far

 

[jondilly1974]

Are those bumper shocks oil filled? They seem really soft. Once the bottom out then they are no longer dampening. ??‍

Seems like the small piece of plastic in the stock mount would be cheaper to replace ??‍

 

[NewSensei]

Are those bumper shocks oil filled? They seem really soft. Once the bottom out then they are no longer dampening. ??‍

Seems like the small piece of plastic in the stock mount would be cheaper to replace ??‍

They are oil filled and I can adjust them but when they bottom out the whole thing moves on the fuel line and the metal flexes. I will probably adjust the spring tension but keep in mind my hand squeezing it may make it look softer than it really is. I've already run into several things faster than I was going when I broke the factory bumper and it's handled it. However, I think I'm going to replace the 20w oil currently in them with some 30w or 40w...once I've got it dialed in replacing bumpers will be a thing of the past. I already spent $25 on replacing with the original and I have two spare rear bumpers now (because I couldn't find just that one piece that breaks in the same place ALL THE TIME) so a little elbow grease and some $15 shocks later I am quite happy with the result.

Remember, this is so I won't have to keep buying a new bumper set just so I can replace that one support which inevitably breaks when you try to have any fun...doing something for the first time often takes a lot of research and money but this was cheaper than all the replacement bumpers combined and I feel I won't have to worry about it as much as that bumper support

If I could have found some shocks that were aluminum I'd have gotten those but these seem to have nylon or some other very flexible plastic so we'll see...

 

[NewSensei]

As an update: I put some silicone fuel tube over the shock shaft and changed the 20w oil to 30w then tested at half throttle on 3s against the curb a few times without issue. So I upped it to full speed on two hits, no damage! None at all, not even seeing plastic strain on the shocks themselves which I thought would be the weakest part. I'll update after a while of bashing, bit too cold right now to keep hitting this thing too hard so...may be a bit but I'll update if anything changes. So far, so good

 

[jondilly1974]

As an update: I put some silicone fuel tube over the shock shaft and changed the 20w oil to 30w then tested at half throttle on 3s against the curb a few times without issue. So I upped it to full speed on two hits, no damage! None at all, not even seeing plastic strain on the shocks themselves which I thought would be the weakest part. I'll update after a while of bashing, bit too cold right now to keep hitting this thing too hard so...may be a bit but I'll update if anything changes. So far, so good

I gotta give you credit for intentionally ramming a curb in the spirit of science ????????

 

[NewSensei]

Are those bumper shocks oil filled? They seem really soft. Once the bottom out then they are no longer dampening. ??‍

Seems like the small piece of plastic in the stock mount would be cheaper to replace ??‍

I added some fuel line on the shock shaft and changed the oil to 30w, it is dang near perfect...full speed impact tests (4 against curbs and brick wall) show no sign of stress yet...I couldn't have pretended to do that with the stock bumper support! Working out great!

I gotta give you credit for intentionally ramming a curb in the spirit of science ????????

I have to prove the concept, is it good enough to make replacing the support constantly a thing of the past or would it be better to stay with just spending $10 every other bash. I also rammed a brick wall a few times and the temp here was around 50°f, no breaks yet! All just in case someone Google's this subject some day...for posterity and all

SCIENCE! LOL

 

[NewSensei]

So I found a use for all the spare rear bumpers I have before making this mod, now maybe my suspension arms won't take such a beating

It's a COMPLETE bodge, just zip tied on...proof of concept I guess but it looks decent and sticks out further than the stock bumper...

 

[NewSensei]

So I broke the first set of shocks and decided to go all aluminum with larger gauge shafts and I think that's the way to go.

https://www.amazon.com/gp/aw/d/B016Q85BTE?psc=1&ref=ppx_pop_mob_b_asin_title

Filled with 30w oil and put a piece of silicone fuel line on it so that will take most of the initial hit before the springs really get involved (currently have pieces about 50% bigger than what you see in this photo) and since these have ball joints on them they're a lot more flexible so I am hoping I won't see the sheering issue I had with the other shocks which really only broke because I over tightened the end that connected to the bumper.

 

[Neilski]

So far in the month or so I've had my Senton I have only broken the front bumper but I have had the aluminum plate that holds the A arm pins fall out a couple of times. Though, I think that was due to the poor bodge job I did on the bumper after the first break flexing the skid plate. That said, I've upgraded to brushless and 3s on occasion (have two 3s and 5 2s) and so far it seems to be holding up well, I did buy and install the center drive shaft support (haven't screwed it in yet since I need to drill a hole) but other than that and new tires it is stock. No leeks in the shocks yet and no broken anything else except the upper support of the front bumper. It really doesn't take much to break that...

Has anyone tried making a spring loaded replacement for the upper support? I've seen the after market bumper but have also heard it doesn't fair much better than the stock one for more than twice the cost... I'm thinking of making an upper support that is spring loaded (or maybe even with small shock absorbers) but before I reinvent the wheel I was curious if anyone else had done this sort of thing and what commonly breaks on the mega/BLX other than the bumper. I may just be lucky, had a few bad landings but those were only after a 6 to 10 foot jump so I haven't REALLY ragged it out but I'm thinking of getting some spare parts to have on hand as well as modifying the front bumper to be a little stronger...

POS make a decent bumper that fits the senton 3s

 

[NewSensei]

POS make a decent bumper that fits the senton 3s

Not sure which you are referring to but if it is anything like tbone's bumper I wouldn't expect too much better of performance from it. Anything with a ridged support will break. That upper support cannot be ridged at all, it'd be one thing if it is the classic single piece that can flex to absorb damage but putting the upper support on removes a lot of that flexibility but at the same time provides support to keep the bumper in place. The problem is that is a weak point and I believe it's designed to fail. With the stock bumper it fails too easily for my tastes and I've heard similar complaints about other supported bumpers so rather than go and spend money on something you'll likely be buying again before too long just strap some shocks on the front.

My goal was to find a better solution that wouldn't have me replacing parts all the time and I think I've hit the sweet spot. It was easy to do and cheaper than two replacement kits for stock bumpers just to not use 85% of (I bought a few before making this mod). That said, the first iteration was fantastic but not the best. However, I've more than confirmed the newer all aluminum shocks with the larger gauge shaft is superior in all ways to the crap I had before. Even the smaller gauge shocks took quite a beating but these bigger gauge are triple the threat. I can now confidently hit things and only cringe slightly rather than recoil in fear as I was before

Lesson learned, always get the largest you can when it comes to something like this. Funny thing is the better shocks cost the same price as the smaller ones but I got four shocks instead of two. All said, this whole mod costs less than the tbone bumper and I don't believe I'll need to replace this one any time soon.

 

[NewSensei]

TLDR, shocks ultimately don't last, they eventually always break BUT I have found a mod that works gloriously! Stock bumper support (new) wrapped in prodigious amounts of silicone tape seems to help prevent easy breakage. I don't know if it is strong enough to ram a brick wall (scared to try) but I do know it'll stand up to hitting a car tire at speed...long as you actually hit the bumper and not the tires...

Anyhow, way cheeper mod to wrap it rather than buy a bunch of after market parts or shocks...while cool and real good while they last the shocks just don't have the durability versus cost to say it's worth keeping. Go with some silicone tape and you'll be happier

 

[rflx]

Thank you so much for posting the whole process of your investigation. The senton 3S is my first RC car and the dang bumper broke on my second run. A new bumper set (why do I have to buy a rear bumper also?) is like 20 Euros here, I don't want to keep replacing that every week.
I will probably buy the replacement once and just try wrapping it in tape. I'm a little sad about your shock-based design not holding. Looked really cool, would have loved to do it like that.
Cheers

 

[Goingnorth75]

I broke my front bumper 2 times in 3 days, going to try zip ties for a short term solution.

 

[Yonic]

I broke so many of those, I'm working on a 3d printed design to replace this part. will share when I'm done.

 

[rkj__]

I broke the skid plate and bumper on my Senton. The stock bumper is not very sturdy it's a common break and seem to be in the same spot also. When mine broke I almost lost the hinge brace didn't realize the skid plate was broke. I made kind of my own fix. I drilled two holes through the skid plate bumper mount into the hinge pin brace and into the chassis then screwed 2 3mm bolts in. I also busted one of the parts on the front of the bumper that most commonly breaks. I took it off and drilled a hole so I could put in what amounts to a threaded rod like a turnbuckle then drilled a hole in the other part of the bumper and threaded it in to bumper. I drilled it off center and could have done a better job but it works. Been running with a broke skid plate and threaded rod piece bumper now run into things and haven't broken it again. Was going to the T-bone route but don't think I will now. It's not really a fix but has worked for me.

I tried repairing this break with glue and cloth tape, but ultimately, the repair was too soft, and it did not hold up.

I read your post, and it sounded like a good idea, so I executed a similar repair, drilling into each peace, and gluing in a small steel nail. It took it's first few hits well. I'm sure I'll break the bumper again soon, but I just wanted to thank you for sharing your idea.

 

[Sosnl]

lol but why all that tinkering? and why not just buy a bone bumper ??