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ThunderDragonCy

Grafting foam bumper onto a buggy chassis - help please on road people!

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I am pretty unfamiliar with on road stuff, but I have noticed they all run these foam bumpers.  RR-03Ra has a massive gap between the buggy bumper and the body and I am not sued to all this space around a chassis! 

20190404_152055 20190404_152108

I have seen 45mm foams on ebay, which would bridge the gap fairly well, but I don't know how to mount them. There are 4 screws on the buggy bumper as you can see, but the foams all seem to have these plastic platforms with two large locating posts. Any on road officiandos got any ideas on a stock bumper mounting that might work here of I might modify? Thanks all! 

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9 minutes ago, TwistedxSlayer said:

TB01 bumper. Sand the lips flat. Redhill the holes and stick a lovely piece of foam on it.

Nice one. I will look into that. 

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I was going to suggest a Tamiya 54819 XL Urethane Bumper; this is the part included with the MAN TGS Racing Truck.  You can cut it back to fill the nose of your shell with a coping saw blade, and then sculpt it further with 60 grit or 100 grit sandpaper.  Cutting and sanding will be messy and it's best done outside or near a trash can.

tamiya-op-1819-1.jpg

Another option is adapting GPM's TT02 bumper and fiber plate to the TRF201, part number TT2200R.  It's a little more expensive.  Or, since they have a good idea, you could always source some FRP, aluminum standoffs, and fasteners, and make your own mounting plate for the foam bumper.

b_tt2200r.jpg

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What about the kick up? It's 25 deg on the TRF201 front end, so the foam will point up at that angle too would it not? Does that matter? 

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Sure, that's a good point.  Depending how much the fiber plate kicks up from the bottom of the buggy, one idea would be to mount the bumper foam UNDER the plate and shape it into a wedge.  You could still capture the bottom of the bumper foam with another fiber plate or washers, standoffs, and screws.  It would be like taking a touring bumper assembly and mounting it upside down.

Another thought is to get a block of nylon machined into a 25 degree wedge, and have some counterbored/countersunk holes drilled at 25 degrees to match the TRF201 front end.  Then drill and tap another set of holes at 0 degrees for the fiber plate, and mount the bumper foam on top as usual.  It's tempting to say "let's 3D print that!" but I question how long a printed wedge would survive all those impacts, even with 100% infill.  I think starting with a block of nylon, shaping it into a wedge, and drilling/tapping the right holes would work better over the long haul.

Another perspective is to forget mounting the bumper to the chassis; instead, mount the bumper to the shell and let it make contact with the front of the chassis.  You could buy a couple of bumper foams and glue them together, sculpt them to fit the nose of the shell, and glue or Velcro that assembly in place.  If you have a second clear shell it becomes easier to check what part of the foam needs more sculpting to fit.

I'm kind of attracted to gluing the foam to the nose of the shell and letting it touch the front of the chassis; it would really stiffen the whole nose of the shell that way and leave the chassis untouched for use with other bodies later.  That way you don't have to install unique bumpers for each body you want to run; the bumpers are already part of the shells.

Food for thought...

 

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If it were me, I'd make my own... cut/heat/bend a scrap of flat plastic, drill holes in it to mount where the stock bumper goes, then attach a block of scrap foam from a craft shop or an upholstery/furniture shop to it with a couple of screws and big washers. But then, I hate spending money on something I can make out of off-cuts for cheap or free. Your mileage may vary.

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@speedy_w_beans All very good thoughts. Although the foam will dissipate impacts, I am not keen on 3d printing. Even using SLS nylon from Shapeways the bumper I did for my DT03 didn't survive long. I think velcro the foam to the shell is a winner. I can't replace the buggy bumper because it has retainers for the front arm pivot shafts, so it would have to bolt on the bottom. The TB01 parts looks very promising but would definitely angle up at 25 deg. 

Thanks for the help chaps. 

 

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Ok, gap measured at 60mm so I have bought a 72mm bumper and some velcro double sided tape. I'll post up the results on the build thread. 

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