TT MTA4 S50 conversion

[j.f.s]

Some progress has been made!

I mentioned earlier that I would swap out the knuckles for some beefier stuff. I went with the Revo knuckles and LST XXL drive shafts. Thanks for the guides and sharing your knowledge mistercrash!

This alters the suspension geometry a bit. The CC between the pillow balls on the stock knuckles are 35mm (~1.4") and the E-Revo measures 45mm (~1.8"). I can see some bumpsteer going on but it's not too bad. I'll be trying different shims and see if I can tone it down. I'm using Mugen MBX6-T hexes. I cut off 5mm from the a-arms so the axles will sit in the middle of the drive cup. This mod with the 6T hexes adds 50mm (~2") in total width.





New hole drilled in the stub axle.






Stock vs mod


Liqiud RC was clearing out their old GPM parts so I bought the following:
1 ea. AGM1012AF08 Silver Alum. Fr Gear Box Brace - 1pr
1 ea. AGM1012B08 Silver Alum. Fr/Re Gearbox Tightener
1 ea. AGM1013AR08 Silver Alum. rear gear box brace
1 ea. AGM1014A08 Silver Alum. Fr/Re Chassis Mount
1 ea. AGM1331F Blue Alum. Skid Plate W/Steering Mou
1 ea. AGM1331R Blue Alum. Rear Skid Plate - 1pc
1 ea. AGM1048 Blue Alum. bushing Steering Blue

I know GPM doesn't have the best rep (on par with Integy perhaps) but for $25 shipped I couldn't resist. Figured the would be stronger than the stock plastic parts at least.

Ball bearing steering:


Front differential


Rear differential:


GPM vs stock

[j.f.s]

Before adding Fullforce upper arm mounts




One side of the front is complete


Radio box mounted:


This is what the radio box looks like with the lid on


Beefier (Kimbrough 124) servo saver


Another GPM part found on E-Bay. Dirt cheap so I'm not so sure about the Ti:


The shocks are in bad shape so ignore the sag. Stock body without bumper




Proline F650

[j.f.s]

More parts are on the way. Updates will follow. :)

[coolhandcountry]

Very interesting!
I have never thought of going to the newer revo knuckles on a Monster GT.
I was just looking at mine today.
Maybe this will be my new project.
Out with the Gmaxx and in with a new improved MGT.

[yzinger02]

I cant help but notice how similar the MGTs are compared to the emaxx/tmaxx.....like some parts seem identical. Did traxxas or Associated make their truck first?

[j.f.s]

Time for an update! :)

New toe links:




New shocks. Mugen MBX6 front shocks with rear springs.


Toe link and shock


Front shock


Modified the shock towers. Removed the extension for the shock mount on one side of the tower


Mugen shock mount




As the Revo axle carriers widen the truck the rear toe links were too short. Two pieces of Mugen MBX-6T shock towers were used as extensions. Need to trim them and seal the cut with epoxy.

[j.f.s]

I've used this body on my 6T so it has a large chunk cut out of it in the rear. That's why there's a lot of duct tape on it

[coolhandcountry]

I like it. :)
Nice looking project.
How does them new turnbuckles handle?

[Overdriven]

Good looking truck! I know you said the bumpsteer isn't that bad, but you might be able to reduce it some. If you buy the "Hollow Ball" kit for the Revo (part #5355X) you can adjust the height of the rod end of the tie rod in the steering knuckle. It looks like you have the rod end in the center right now, I'd try lowering it so its parallel with the lower arm.

You must get a pretty big increase in camber as the suspension compresses too. Is there any way to raise the upper arm mount at all? If you could, it would definitely help with your bumpsteer issue as the rising camber is the main cause of it.

[j.f.s]

Originally Posted by coolhandcountry

I like it. :)
Nice looking project.
How does them new turnbuckles handle?

Thanks I haven't run the truck at all. Hopefully I'll be able to do a test run soon. Won't be much of a test though since we've finally got snow here.

[j.f.s]

Originally Posted by Overdriven

Good looking truck! I know you said the bumpsteer isn't that bad, but you might be able to reduce it some. If you buy the "Hollow Ball" kit for the Revo (part #5355X) you can adjust the height of the rod end of the tie rod in the steering knuckle. It looks like you have the rod end in the center right now, I'd try lowering it so its parallel with the lower arm.

You must get a pretty big increase in camber as the suspension compresses too. Is there any way to raise the upper arm mount at all? If you could, it would definitely help with your bumpsteer issue as the rising camber is the main cause of it.

Thanks for your input!

Yeah, I've been thinking about the Revo hollow balls but haven't gotten around to order them so thanks for posting the part number and saving me some time!

You're probably right about camber. I haven't paid much attention to any angles at all really other than looking at how much bumpsteer I got. It would probably be possible to raise the mounts but doing so would also raise the shock tower so new mounting points for the shocks would be required. Might be worth looking into though.

I'll try and shoot a video of the suspension articulation once I've set toe and camber.

[The Dude]

wow nice work, really !!

love your catch on the shock

can't wait to see it on a vid

[Overdriven]

Looking at the pics I can see the upper arm is pointing up while the lower is horizontal. Now look at the arms like a compass and draw an arc at the ends. As the suspension compresses the upper arm essentially gets shorter faster than the lower, creating the rising camber. Since camber is the knuckle moving in and out from the truck, it always effects toe. Making sure the tie rod is as close to parallel to the lower arm will help, but raising the upper arm mount is the best fix.

Whether or not the issue is bad enough to be bothered is up to you. I don't know much about MGT's but I kinda figured you couldn't get away with just shimming the mounts, that would be too easy! Maybe flipping the mounts over? Just throwing out ideas.

[j.f.s]

I greatly appreciate the input! Both the rear and the front upper arm mount are bolted directly in the frame. The front ones are mounted in an angle though. I'll take some pictures later on


Just realized that clicking the images wont show them in the original size so for anyone who wants to zoom in here's the album link: http://bit.ly/s5G5fv

[Krawlin]

Camber rise can be a good thing, especially on a heavy MT that has quite a bit of body roll, the camber rise will cause the tire to stay more perpendicular to the ground, as a result it maintains a larger contact patch as the chassis rolls away from the inside of the corner.

With camber rise, say you are moving pretty quick and make a hard left turn, the chassis rolls to the right, and the right side (outside) suspension compresses, causing the camber to rise up which keeps the outside tires to stay more perpendicular to the ground, maintaining a larger contact patch and thus more traction in the process, which means you can go faster through the corner.

Now the same situation without camber rise, you make a hard left turn and the chassis rolls to the right, and the right side (outside suspension compresses, the camber doesn't rise and it actually tilts the wheels towards the outside of the corner, greatly reducing the amount of area the tire has in contact with the ground, less contact area means less traction, resulting in the truck wanting to lose grip and push to the outside of the corner. Be it a banked or flat corner on a track or just bashing in a dirt field, camber rise is beneficial to handling in all situations.

Take a look at a 1/8 on road race car (Mugen or Serpent for instance), you'll see that their rear upper suspension links are angled very steeply, high at the hub and low at the chassis, so as they corner the camber rises quickly and keeps as much of those fat rear tires in contact with the ground as possible. Camber rise is very good in on road situations and its just as good in off road situations, it's not something you want to try to get rid of, however you can have too much and there is a fine line between just right and too much, but don't try to eliminate it.

I think your MGT will handle much better than a stock one with the addition of those Revo knuckles, if there weren't anything else factoring in to the handling there, I would say that alone would make a big difference.



Also, as far as being able to adjust camber rise, well that can get a bit confusing. If I remember correctly, changing the camber rise at the knuckle/hub (which would be changing the spacing of the upper and lower arms at the wheel) will not affect the car's roll center, but changing the roll center (distance between the arms upper and lower arms at the chassis vertically, as well as horizontally) will affect the camber rise, while typically very minimally, it does change the camber rise. So if you were to raise or lower the upper arm mounts on the MGT, you would be changing the roll center directly, and the camber rise would be changed as a result of changing the roll center.

I say run with it like it is, my MGT turned like a semi truck (stock knuckles, etc.), I'd imagine yours will handle alot better even if it does have some minor bump steer. And if you want some more info on suspension adjustments, download a copy of the Hudy Off-road & Truggy Set-up Book, tells all about that stuff.