Joe's TH's with BMRC and Traxxas bellcrank

[honchojoe]

I picked up a stock RTR THs from a mate cheap and it also came with a Blue Monkey RC (BMRC) front shock tower plate new in a packet. I did some research and found it can be used with traxxas slash bellcrank steering but had no luck finding any actual instructions on how to do it. So I took photos along the way.

Stock form when I got it.




Since it was coming apart to do the steering I replaced the plastic gears with steel ones.

This is the BMRC plate with the traxxas bellcrank bolted on. There are 2 mounting pins that came with the plate. Optional purchase from BMRC. The bellcrank must be the alloy upgrade version as the arms all need moving around.



Bolted on but the arm that connects to the servo was wrong and needed to be removed and adjusted until it moved in both directions without hitting anything. Final position was this.



The arms on the bell crank system are pressed onto the 2 hex posts and can be removed and placed back on. They can also be moved up or down on the hex posts. You need to slide the main arms up as far as they will go without anything hitting the BMRC plate. As per this pic.



Ensure it still swings in both directions without hitting anything.



The other arm needs to be adjusted as high as it can go also but leaving enough room to swing under the plate.



I used the factory drag link that was used on the old setup. I fitted a Hitec servo and cut down a clamping servo horn. I also put a slight bend in the drag link and trimmed the edge of the plate a little as it was rubbing. If I had a shorter servo horn it wouldn't have been required.



View from the other side.



Please note some of the pics taken where befote I got the lower arm set at the right angle. Make sure you set that correctly according to the 2nd pic not the following ones.

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[honchojoe]

I then fitted some gmade 85mm shocks.







However those shocks need to come apart again and limited a little as the drive shafts are popping out in certain scenarios. Common issue with vertical shocks on a THs.



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[honchojoe]

As the BMRC front plate also accommodates a front mounted battery I converted it to flip front.

If you look at the frame on the front you can see the point where I cut.

It just fits a 2200mah 3S.



Then I removed the screws on the side and and am currently using a pair of large body clips in place of the screws when closed.





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[honchojoe]

Not sure why the pics are sideways. I'll try to work out how to fix that.

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[honchojoe]

So far it has been running well other than the dog bones popping out. I'll need to pull the gmade shocks apart and fit an oring inside to limit the travel. Or somehow raise the mounting point on the BMRC plate a few mm. Also I've found the lipo cut off is not working on the original esc which is very odd.

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[MaxxPain]

I bought my Twin Hammers used and it came with the same setup. I had trouble getting that system to work correctly. The RED drag link on the Traxxas Aluminum steering, I think is too long. When you press down on the suspension, the wheels toe outward quite a bit and caused me odd steering when driving. It was a few years back when I did this and maybe yours if fine or maybe different. But maybe check the steering when you cycle the suspension. Wheels should stay straight.

[honchojoe]

It does do that. And most bellcrank steering setups will do this if turning and deflecting the suspension. It's something I want to eventually address but not to worried about it at this point.

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[honchojoe]

The reason it bump steers is due to the pivot point on the bellcrank is in a different location to the suspension arm pivot so the steering knuckle is either pushed or pulled. To get rid of this you need to modify the bellcrank somehow so the rod end mount is perfectly in line with the swing arm pivot point.

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[MaxxPain]

What I did to fix it was replace the steering with IRIE's Bellcrank setup. I also changed to the GCM Plate. No more problems. Steering works awesome. Plus I haven't had any dog bone issues popping out.

[jimmiejump]

Originally Posted by MaxxPain

What I did to fix it was replace the steering with IRIE's Bellcrank setup. I also changed to the GCM Plate. No more problems. Steering works awesome. Plus I haven't had any dog bone issues popping out.

Specifically what battery are you using with the GMC plate?

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[MaxxPain]

I use a 2200mah 3s pack that I put in the rear.

[jimmiejump]

Originally Posted by MaxxPain

I use a 2200mah 3s pack that I put in the rear.

Thanks but I'm looking for a battery to run up front within the stock cage dimensions.

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[MaxxPain]

Yes I agree. I would too. But I haven't really looked that much for a 3s pack. I bought a shorty pack hard case before, but it was too too tight.

[jimmiejump]

Originally Posted by MaxxPain

Yes I agree. I would too. But I haven't really looked that much for a 3s pack. I bought a shorty pack hard case before, but it was too too tight.

Yes it seems if you want to run a forward battery purchasing the GCM 3d printed hood is a must. Which I'm not crazy about the look. Would pefer to run stock cage and fab my own aluminum body panels. Maybe someone with more experience can join in here with some advice, measurements and pictures. Otherwise I can see my wallet suffering.

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[honchojoe]

I used the BMRC plate because it was given to me with the THs. Also the GCM plate is 4x the price. The Irie bellcrank is great and if I had the GCM unit I would be running it.

As for the battery I run a Zippy 3S 2200mah lipo in the front. It just fits. But it's very tight. Slightly shorter would be better.

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[jimmiejump]

Originally Posted by honchojoe

I used the BMRC plate because it was given to me with the THs. Also the GCM plate is 4x the price. The Irie bellcrank is great and if I had the GCM unit I would be running it.

As for the battery I run a Zippy 3S 2200mah lipo in the front. It just fits. But it's very tight. Slightly shorter would be better.

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First let me apologize for jacking your thread. Space is at a premium however and seeing as how either option requires cutting the forward part of the cage I'm leaning towards fabbing a whole new set of front frame panels from .035 5052 aluminum accommodating a larger 3c batttery. 1:1 grassroots crawling is a very diverse sport and body work wise there's all kinds so I'm going that way.

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