Cen Gst based 6x6
 

Ok, time to do another 6x6...

Actually I am getting ahead of myself, but I am waiting on parts to fix the other 10 builds I have so why not start another build!!!

So I just received a cc 2028 motor. Big and powerful looking. I would take a pic but everyone knows what it looks like.

I also have a hydra hv18 boat esc. Got it from Mike via BB16, he used this esc in his baja (when he developed the baja conversion kit?) and had no isses with it. So I figure it should be ok. I have 10s of 3200 30c flightpower lipos, and a few 1/4 scale servos to choose from for steering.

So my plan is to get a NIB Gst off ebay, sell the offending nitro crap and radio gear. Should be able to get a roller for around 250-300 that way.

I will make a new rear skid plate, with an extension to hold the lower bace that the tvps mount to. That way I can make another, shorter, set of tvps to will connect with another complete gst rear section (bulks, diff, arms, etc).

Keep in mind that the gst is alot like the savage, tvp design. The bulks are multi piece, which allows me to easily add the necessary parts to attach a pair of tvps to the rear of the existing truck.

Now here is the fun part:

I plan to make a mod 1.5 transmission (kinda like the kershaw savvy center drive) that will sit between the center and rear bulks. The pinion will likely face the rear so the motor can get closer to the center of the truck.

The trans will be made up of two plates, that will attach to the new tvps. I will use 8mm shafts, and 2 30t spurs,1 15t pinion and 1 12t pinion. This will give me enough reduction to get mid 40s with the 2028 on 10s and the 2.8 reduction given by the cen diffs. I will run the big cen tires, as the are just too cool!

I would do a std spur and pinion, but the size of the spur would be wider than the tvps, and I would like to keep the individual gear ratios closer to 2:1 to cut down on wear. I will be using plastic spurs, but they should be strong enough.

The gear arrangement is: 12t pinion on motor driving a 30t spur that shares a shaft with the 15t pinion that drives a 30t spur on an output shaft that will go to the center and rear diffs. All mod 1.5 to handle the power and give enough spacing to clear the motor. I have not decided if I should run a solid output shaft directly to the pinion on the diffs, or use some sort of dogbone/cvd. The entire assy from bottom of the output spur to the top of the motor can will be close to 5". I could stagger it some to reduce height, but I want the motor centered, as it weighs alot. And I have a limited width between the tvps to work with. Not exactly sure on the dimension but it look to be close to the savvy width.

Now I will have to use mech brakes, so I plan to leave the stock trans in there and use the stock brakes. I will likely remove the unused internal gears. The mech brakes are supposed to be pretty good on these trucks, we will see. I may go with a 1/4 scale servo for the brakes too. Also, the stock center driveshafts will be left to power the front diff, for true 6 wheel drive.

Batteries will go where the nitro engine used to be, on a custom battery tray. Not sure where the esc will end up, maybe on the side of the tvp behind the center bulk.

I will have to make a pass thru diff. Looking at the pics the cen may have a plastic diff case, or it may be al. Might get a machined pass thru case made, or plastic weld one together like i have done before. A fair amount of load will be going thru this diff, so an al case may be mandatory.

I have to do some measuring, but I guess this truck will end up with a 26" wheelbase. Figuring I want about 4" between the rear tires and they are 7.5" diameter. Overall length will be about 3 feet. Stock the gst weighs 17lbs, so I figure th 6x6 will end up around 25lbs.

Thoughts?

Nice1 Linc! Looking very forward to this CEN Build! i havent seen a decent one yet....
Suscribed.

Sounds like it will be a very big beast!!! and i guess you have thought of everything you have needed to think of!
I just hope your custom tranny (which sounds quite kl) will hold up to the power!

Thanks, I have been "mentally designing" it for a few weeks. I like to type out my plans so I can go over them. Plus i tend to get stuff figured out and then forget it, so it is good to have notes!

I think the tranny plates will be something quite thick, like 10mm al, possibly 7075 as the weight of the motor will be on one of them. Depending on space I may tie them together with a few stand offs, so I can remove the tranny as a unit if needed.

I am selling of stuff so I can pick up the truck, then I will sell of the nitro stuff and gather the other required parts from the ebay chop shops. I found a few parts last night that were way cheap so I picked them up.

7075 alloy and 10mm thick is going to be expensive, and i think a little over kill. Yea it would be awesome, but if it costs a substantial amount more... just go with regular alloy as 10mm is thick enough!

Really looking forward to this badboy come to life!

Would think 5mm or 6mm would be sufficient, especially since there are effectively three bulkheads plus the tranny tieing the TVPs together.

I was mainly going with 10mm as the tranny bearings will likely be 8x16 bearings, and I think those are 5mm thick. I will have to see what material I can come up with. I do not need much, a sheet 6" by 10" would likely be enough.

i would use 7mm.. my alloy diff mounts are 7mm... so thats what i would use personally.

My new custom mounts are being made 7mm thick as well.

Ok, I will look into what material I can find. I also have to price the spur gears and 8mm bar stock. Something tells me this custom tranny is going to be pricey when everything is said and done...

Oh you meant 10mm for the tranny, not for the tvps? Well you could do something like what Jahay had made up for the suspension brackets and use a piece that holds the bearing and another thinner plate that keeps it from falling out.

Are you going to get the mount machined by dejan as well?

Yeah, the tvps will likely be similar in thickness to the stock cen tvps. I will brace them with the trans plates and also have a few other crossbraces. I also plan to make center skid plates, which will add strength.

Do you have pics of what Jahay did, or maybe a link?

It'll never happen - lol

See this post.

Ha, you may be right... But you have been around to see all of my half finished projects...

This ne will invole alot of machined parts (= big money) so once I buy the truck and start getting stuff made there is no turning back.

Thanks.

Ok, I understand. That may be an option, and I can make that stuff myself. The pass thru diff case will be the expensive part. This will have to be made to fit the cen diffs as they have weird ratios. I may be able to make on out of steel but it may get a bit involved. I can weld, but lack machine tools, and my local machinist is a bit pricey.

I would like to get cases made for the lst diffs, as they can be used in both lst and maxx based trucks, expanding their versatility. Building a 6x6 truck is very easy, and a tvp based truck is even easier as tvps are very easy to cut and drill. A cheap badsaw and small drill press are all that is needed. And to be honest you could make the tvps with a reciprocating saw. So 100 bucks for tools.

Linc, clear your pms

would you use the drill press to hold your drill and use like a mill to cut out sections in your tvps?

if so, what sort of drill bit would you use... and how safe is it putting so much side load on a drill?

I have not had much luck with using a mill bit with a drill press. I just use a skil saw to cut out stuff. Drill a hole to start, and finish with a file. I am pretty quick once I get start.

a skil saw? hmmm... i should get one of those. Does it make light work of alloy then? What does it look like so i dont get the wrong tool :/

Sorry to thread jack linc

Sure he means a jigsaw; "Skil" is just a brand. And you can get metal work blades for it. Personally I don't like the jigsaws for cutting metal, I never have good luck with it but could just be me... I went the route of getting a router with carbide tip to do it.

You do need good blades. The problem you run into is that the bade will load up with al and you effectively lose the teeth. I have a dewlat jigsaw and it has a function that offers a variable oscilation of the blade. So imagine the blade reciprocating, and moving forward and backward in line with the material. This helps the cutttings escape and stops the blade loading up. Works like a charm. Still not as good as a cheap badsaw, but you can cut an area out inside of something with a jigsaw. I spent around 90 bucks for the jigsaw, and the bandsaw was about 100. Setting up a bandsaw is a bit of an art, but you can use a finer tooth blade and get very nice smooth cuts.

I love my delta band saw for cutting aluminum. Candle wax works awesome at keeping debris from sticking to the blade/teeth. Even on softer aluminum.

Pretty sure I have a delta too. I will give the candle wax a try. Seems like the cuttings get lodged between the blade and the "tires" on the bandsaw wheels. I have had to replace the original tires already and have another set as spares. The stock tires were very hard plastic, and they dried out and cracked. At least the off brand replacements seem more like rubber.