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T-maxx Hinge Pin Nightmare!

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BrowneR

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I have a .21 extended t-maxx which weighs in at about 13lbs (uk).

Why do I keep bending the front hinge pins?
I could understand that if I was crashing into trees or landing huge jumps - but I'm not. I recently fitted some Lunsford Titanium pins and after about 15mins ripping up the street in front of my house both the bottom front hinge pins were bent!

This totally screws up my toe-in and camber adjustments and makes the trucks handling erratic. But worse than that i'm afraid its going to damage my bulkheads. (and i dont have much money for replacing parts)

I have alloy bulkheads and shocktowers with stock A-arms and 40size proline wheels. What can I do to strengthen my hingepins? Is Titanium the strongest avaliable? (i know it allows a bit more flex which i thought would help?)

Its just the front pins and mostly the rear end of the front-lower pin if that makes sense.

Any help/personal experience welcome! Thanks
 
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Thats amazing that you are bending the lunsford pins that quick without crashing or anything.... You've got me stumped...
 
wow... i've nailed a tree wot and didn't bend a lunsford hinge pin!
all i can think is check and see if your bulkheads are straight
 
get RPM arms too....they help support the A-Arms w/o those castor clips...you loose the castor adjustment but who uses those on an MT anyway???
I use the stock pins on my maxxes cause they all bend at some point...I'd rather have a weak link in there somewhere to snap...the stock pins are cheap too...keep a buttload of them in my box and I haven't needed to change one in a long time......
 
Thanks for the info.

Really got me puzzled - why's it only me thats having these problems!

I'm thinking I could switch back to stock plastic bulkheads and see if that will cushion the blows a bit. I might try the RPM arms if you think that would provide extra support but i rekon its the larger wheels that are stressing things.

I feel like drilling out my bulkheads and a-arms and fitting big'n'fat 4mm pins! grrrr....

bent.jpg

The arrows show where the pins are bent inwards causing the A-arms to bind on the skidplate.
 
just had a thought, could i construct some kind of hingepin brace to fit across the rear of the pins (just below the red arrows in the pic above) and hold them at a fixed distance apart? I could use the longer pins from the rear of the truck to allow the braces to be fitted.

Found a set for a stadium truck and gave me an idea, but i've never seen any for a t-maxx. Anyone ever seen/tried any?

FFRChingebraces2.webp
 
Nice! wouldnt mind a pair of them up front - ouch on the price though, especially with uk shipping :(

I'm gonna give my homemade job a try and see how it holds up with some bent-and-then-straightened lunsford pins. I've managed to make a thin steel plate which fits on behind the c-clips with the stock length pins but I'm not sure if it will be strong enough to hold. Only time will tell...

Thanks for all the suggetsions and i'll keep my eye on ebay for some rc solutions bulkheads... :)
 
Wait, you said they were bending just driving up and down the street, you didnt say anything about crashing... You shouldnt be bending Lunsford pins easily, or even at all...
 
Thats correct i havent crahsed with them but maybe driving isnt the best word - i was kinda throwing it into the turns with heavy braking but it didnt flip or anything. As they DO seem to be bending i thought it was best to look for a solution. (or maybie i should be looking for the cause?) Hopefully the brace will do the trick because it certainly looks the part. I'll let you guys know how i get on.

I'm now on mark2 which is a 3mm aluminium block with longer lunsford pins made for the rear of the truck and a slight steering mod to make room for the brace. fingers crossed it'll stop raining and i'l be able to put it through its paces tomorrow..
 
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the mod seems to be holding up nicely even after a few bad landings and rolls. Can recommend it if your having problems just make sure you get your measurements right so it’s a nice tight fit with no slop. Now I must be off - i have some body mounts and shock towers to straighten...
 
well ebay actually but it was from a reputable guy in the US. it arrived in a lunsford marked pack with all the origanal stickers and c-clips and it all looks genuine but you may have a point... still at least things are holding up now.

It just the erratic tuning on my picco maxx .21 thats bothering me now. Really gets me pissed off sometimes when it wont hold a tune for more than a 1/2 hour and even when it is tuned it runs erratically and sometimes acts rich then second later its pulling wheelies because its so lean. and i know it has air leak written all over it but I'm having problems locating it
 
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What have you sealed? Or have you sealed anything?

Pull the engine out, clean it with DA thoroughly, pull the carb and backplate. Clean surfaces really well with DA. Put a small bead of sensor safe high temp silicone around the base of the carb, install the carb. Put a small bead around the backplate or crankcase where the backplate and crankcase connect, put the backplate back on. You have to let it cure for at least 24 hours. The longer the better.

Pull the high speed needle off the carb, seal the banjo fitting as well on the fuel inlet.

If you have erratic problems after this, the leak is in the fuel delivery system somewhere. Replace lines, check the tank for cracks/leaks, replace or at least check the header gasket and coupler for deterioration.

Good luck!
 
thx man I'm gonna give it a go - sounds like hard work tho :( hehe
 
I had the same issue w/ mine..it's the carb body where it seals to the metal throat.....PITA to figure that one out...I threw the engine on a stand after cleaning it real good and sprayed silicone grease type lube around the carb while it was running and looked for tiny airleaks.......the carb on theat thing is notorious for running like crap and I can't find one to fit it......also the slide for the carb should be fine polished more than they do from factory....if you have any point that feels like it's binding, take it off and use a fine sand cloth to deburr and then dremel polish it after...made a huge difference in mine....still is a bitch to tune but stays tuned a lot longer now.....also I find that when that mill's temp spikes high after running well for a while....DON'T re-tune it....I let mine cool down for a lil bit and then run it again for 20-30 mins or so and it's tuned right again but it will do this cycle all day.....otherwise I'd find myself chasing the tune all day again.....I don't think that engine like endurance running at all.....
 
Are your diffs too tight maybe? If so, then the front may be binding up with the rear tires pushiing them, thus bending your pins.

Pull the front diff to see if its stiff, it may be your problem. I had something similar on my maxx. Your case may be the same seeing that you are running a .21 picco rather than stock.
 
if the front one is binding up while the back one isn't, especially with a picco .21 engine (2.38hp) the back tires are pushing harder than the front ones are pulling. There is an imbalance of power distribution.
 
So, that means a 2wd would bend the front pins all the time, since there is no distrobution to the front... Your theory doesn't make any sense.
 

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