3DServisas Fatboy 320 Thermal Expansion and Squeaking/Excessive Resistance.

I have noticed that on my 3DServisas Fatboy 320 drives and hangars, as they start to heat up, whether from the ambient air or motors heating up and transferring that heat into the rest of the drivetrain, the truck will expand just slightly and compress the rear rubber washer. When this happens, an extremely loud squeak develops, with increased turning resistance in the rear truck and a loss of smooth turning. I have found a way to demonstrate this by heating up the trucks by going for a longer ride and coming home and spraying some computer duster (difluoroethane) on the rear of the truck turned upside down so it releases the difluoroethane in liquid form, quickly cooling the area, as shown in the video attached and as I can feel by standing on the trucks and turning it, this cooling results in less squeaking and less resistance leading me to believe that thermal expansion is the root of the problems that I am facing, there is still some squeaking but not on camera, I sprayed more of it on and basically all of the audible squeaking went away. For context, this video was taken at the end of a 14-mile ride with 76*f ambient temperature. This problem does not happen in the winter with cooler ambient weather or often at the start of a ride when the trucks have not had any time to warm up from friction or the motors. Has anyone else had similar problems with this drive assembly?


Forgot video

You running the orange mbs bushings or
Something else? Lube the bushing top and bottom.

It’s a common thing apparently with hyper trucks.

I’ve personally not have had that happen to me on fb320 and mbs bushings 2 sets of them

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Orange MBS blocks, It’s not the bushings, I checked, I took both bushings out and twisted the trucks and there was no change, still squeaking like crazy.

Lube those king pin bushings I suppose.

There is a process to make sure those washers on the king pin are on straight to prevent squeaks as well.

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soap bar shavings

metal on metal lube/grease for pin maybe

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Ok, I disassembled both truck assemblies and cleaned everything and used some silicone lubricant and I would say It got rid of about half of the squeaking, less but it’s still there, then I switched the order of the washers and swapped the position of ones with higher wear with the ones that had minimal wear and that seems to have helped a little more, I’ll go for a ride tomorrow and put the results in this thread.

How many miles you got on those kingpin bushings? Are they the yellow ones from 3D servisas? Or the OE ones from mbs?

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The yellow ones, they were very dirty and had some signs of wear and scuffing but still looked all right.

about 1000 miles I would guess, I don’t have a logger

You send your clip to @3DServisas at all? See what they say

No, I haven’t yet, I didn’t think about doing that, I looked at buying new kingpin bushings but then I saw the price of shipping and closed the tab.

I might have a pair of new ones. Let me look. Are you based in North America

Yeah, Nothern California.

They didn’t fit any of the mbs base plates I’ve owned.

Did you grease the needle bearings with bearing grease during assembly? This sounds like everything is dry and squeaking because of that. Adding grease also gives some of it to the kingpin bushings during use.


I did not assemble this drivetrain so I don’t know what was done during the setup, I’ll try it.

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@ARCTIC did you end up resolving this?

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Sorta, used some spray silicone on the kingpin and that helps a lot but it’s not a permanent solution, and when the drivetrain gets really hot with high ambient temp like I was saying the OP, they will still feel like there is a noticeable amount of resistance if they arent freshly lubed.