What things to look for in an aluminum chassi?

[Shea al'Thor]

As the title says: what are some things that you guys look for in an aluminum chassi? I've been looking around and I've noticed a few different brands of Al chassis out there and I was just wondering what some of the different pros and cons of each was.

Thanks
Shea

[dnvrldrdg70]

my main concern is one that weighs about the same as a factory chassis. or even better one that weighs less. some are really heavy, even seen a few that weigh more. type the name in google and see how many people complain about it. thats another deciding factor.

[Popoxx]

Weight. Ground clearance. Design. Direct fit. Alu quality.

Show us what alu chassis you like and we will tell you the pros & cons

[Mudweiser]

Personally i run the FLM chassis for the newer emaxx. Very durable, everything fit with no problems, and comes with the center drives. Looks rather nice too. Looked at most all of them when i bought this one..but the best bang for the buck and backed by warranty was the FLM one.

[PowerToTheMaxx]

Does UE make a Al chassis for the Maxx?

I'd go with the FLM or maybe the KD LCG chassis. The nice thing about the KD is that Dan will probally custom make it for little extra charge.

[Popoxx]

The UE SuperMaxx™ EXT Lightning Chassis was for the E-Maxx but you won't find one easily and cheap... Idem for Gorillamaxx chassis.

In fact, only FLM and KD chassis are available reliable alu chassis. You can't go wrong with them.

[Shea al'Thor]

I was looking more at a custom chassis rather than one of the normal ones like flm or kd. It's made by True Speed N-gineering (dont bother looking them up... No website yet...) and looking at the CAD models it looks like it comes with everything that it needs to make it a direct fit. Looking at it it's going to probably weigh a little bit more then stock but the chassis converts the e-maxx to a plate/tvp hybrid type chassis that includes a roll cage that ties together the shock towers, front and rear bulks and chassis. It also lowers the battery mounts. The CAD models aren't quite done yet but I'll post up what pictures I have a little later today.

Shea

[Popoxx]

Pics would be great indeed The idea sounds good.

[bentrocker]

Another thing to consider is customer support. FLM's is great. Most anything you break they will replace.
I take it you are looking for a low cog chassis ?

[Shea al'Thor]

Alright everyone here are some pictures of the True Speed N-gineering chassis that's in the works.

Some pics before the cage was added:










Some drafting for the shape of the cage:


Some pictures from after the cage was added (some of the shocktower and bulkhead mounting points are still being worked out and well as the spacers that will go between the 2 TVPs):
pic showing the size of the battery box (40mm spacer is included in the kit for 3s packs):





continued in next post...

[Shea al'Thor]

continuing...

There will be 2 different mounting points for the upper battery box holder, a 25mm spacing for 2s packs and a 40mm spacer for 3s packs. also the chassis could be used without the top plate without reducing the structure of the chassis too severely:
25mm:

40mm:


The shocktower is keyed to accept rpm bodyposts:

And the roll cage will mount to these tabs sticking up from the top:

And here is the whole shock tower:


So what do you guys think so far?? I would love to hear some suggestions

Thanks for any input
Shea

Oh and btw just in case anyone was wondering, True Speed N-gineering is a rc hop-up company in the works. I'm an engineering student in collage and since I am working with a CAD program and CNC mills I figured I'd make some custom parts for my Maxx to get some extra practice i might even expand it as a side job once I'm done with collage too.

[bentrocker]

I think it looks pretty similar to a FLM chassis. A lot of cool ideas in there. I like the cage.

[PowerToTheMaxx]

Ya, an intagrated cage, and one that alows easy axcess for the batts. Also factor in space for a single 4s or 6s in my oppinion, or 2x 4s if you want the castle 1/5 system (that would me insane power in a maxx BTW).

[Shea al'Thor]

If you wanted to you could take off the upper battery box tray for the use of even larger packs your only trouble then would be strapping them in since the loops the straps go through are in the top plate. There is also a 1mm sheet of carbon fiber inlayed into the lower battery tray to protect the batteries from debri kicked up my the wheels.

One problem I ran into while designing the chassis was that the TVPs had to be spaced 60mm in order for them to fit around the tranny. Since the stock spacing is ~50mm the chassis won't work with the stock skid plates and I'll have to use custom ones but they will be made from 2024 t3 aluminum which is basically the equivelant of spring steel, aka it takes heat and a metal bending machine to bend the skids.

I'll probably end up making the prototype out of 5051 al to keep costs down and because it will mill a lot faster than harder grades. The end product will be all 5mm 7075 t6 al with 1/4 inch thick shock towers.

Keep the critiques comin
Shea

And really truth be told, modifying the CAD model of the chassis for a custom height battery would be really easy.

[Shea al'Thor]

When browsing the erbe section of the forum I noticed that a lot of people who used hardcase packs ended up having to hack up their chassis due to the removable leads that came out of the top of the pack:
[IMG]http://i1036.photobucket.com/albums/a447/Shea_alThor/***************pic.jpg[/IMG]

So when I designed the top of my battery boxes I left 3 slots to allow the battery leads to be easily plugged in without dremeling the chassis:


Shea

[bentrocker]

That batt hold down idea is cool. That really isn't an issue with the maxx though. When you go to the 3s hard packs the hold downs aren't high enough so you have to mod the chassis so you can use straps to hold them in.
An adjustable hold down would be cool for 3s 4s hard packs.
Also I didn't notice if your shock towers had a place for body posts.

[Shea al'Thor]

That batt hold down idea is cool. That really isn't an issue with the maxx though. When you go to the 3s hard packs the hold downs aren't high enough so you have to mod the chassis so you can use straps to hold them in.
An adjustable hold down would be cool for 3s 4s hard packs.
Also I didn't notice if your shock towers had a place for body posts.

In one of the pictures I circled where the body posts mount. I designed it to work with rpm posts since theyre a better blend of plastic and flex more on impact, reducing stress on the towers. How tall are 3s hardcare lipos? The top battery plate could be removed for the extreemly large packs but like I said it would be really easy to make some mods to the chassis right now.

Thanks for the thoughts
Shea

[Popoxx]

This chassis looks heavy, have you already calculated its weight?
A roll cage is useless with an alu chassis + alu bulks. But it's good to protect the body.
You could lighten the alu battery cases if you replace the top plate with a simpler system, like this one for example (Stampede 4x4 VXL):



RPM body posts aren't sold separately so it will be easier to buy Traxxas body posts (and Proline sell similar posts, part 6003-10).

My 2cents ! Nice job I follow it

[SLASHFWRD]

I do like the design concept. Seems like it would make it much heavier though. Will this be considered a LCG chasis? I will be following this thread as I am very interested. Looks great!

[Shea al'Thor]

Pitty about the rpm posts... I guess I'll have to change that then. As for the weight, I just had a thought. What if I were to mill out the bottom of the chassis and other parts so that they were only 3mm thick in the center and leave it 5mm thick around the screws and edges? I'll edit this post and put up some pics after I try out the idea on my 3d CAD software later tonight when I get home.

It will be a lower cog than stock and the high flm chassis but it won't be as low as the flm low cog chassis or the gorilla maxx chassis since Im keeping the ground clearance the same.

Also, what are the screw hole locations and footprints of some of the popular brushless ESCs for the maxx?

Shea

[bentrocker]

Popoxx just wondering why you think a roll cage is useless? I like the idea of some sort of protection for the motor on the 3908 tranny. I am always worried that on a hard upside down landing that I may bend the motor plate because it is the highest point on the truck. I don't think it has to be so large. Maybe just a hoop to protect the motor.

[Popoxx]

A rollcage is great to rigidify a fragile/flex structure (stock E-Maxx chassis for example ).
pdcsq uses stock chassis and bulks with a rollcage and he has never broken these parts.
I use an alu chassis+bulks setup and I've never broken these parts too.
As I said, if I wanted to use a rollcage with an alu structure, it would be only to protect the body and electronic stuff.

[Shea al'Thor]

As promised, here is a pic of my idea for lightening the chassis a bit (even if I did get home a little later than I anticipated lol )
---the pink is to help highlight the area on the bottom of the chassis that could be removed to reduce the weight.



After removing some material from the bottom of the chassis the pink spots will be 3mm thick and the gray is 5mm thick.
I could do this to some other parts of the chassis as well such as the TVPs and battery trays which should help reduce the weight quite a bit. By just doing this part of the chassis, I was able to reduce the weight of this particular part from 160.8 grams (0.36 pounds) to 136.3 grams (.3 pounds). Admittedly its not all that much but if I were to do it to the majority of the chassis components it would bring down the total weight quite a bit. I might be able to take 1mm of material more out from the bottom (it would only be 2mm thick in the pink spots then :/) and that would bring the weight down to about 124 grams (.27 lbs). I'll have to do some structural analysis on it before taking another mm off.

The roll cage shouldn't add too much weight if I carve out the inside of the cage like I did to the chassis. I always liked the idea of having a cage on my truck and the option to run without a body if I wanted and to have some protection for the motor and electronics

I also just realized that I can make all the inside corners in the chassis half the radius that they currently are which should also help reduce the weight. I found a 1/8" (~3mm) cutter and a .070" (~1.75mm) cutter for the vertical mill so that should take a ton of weight off since before I was making all the corners for a 1/4" cutter.

Thanks for all the feedback,
Shea

[Wildman4910]

Looks good to me, not a fan of cages though.

But it seems you have most of the bugs worked out of the design tho.

[PowerToTheMaxx]

Looks pretty good. U dont know how lucky you are to have free axcess to those machines and computer programs.