Rotare' twin hammer - on the cheap

[Rotare]

So the Hammer section of this forum seems a little quiet of late, so I thought why not post a few pics of my ride. It's nothing special compared to some of the other quality rigs on here though!



My hammers was purchased on eBay as a second hand unit, but seller said it was used only once. It certainly looked brand new but I managed to buy it less than half the new price. I immediately starting doing some mods once it arrived. I like having a go at making what I can, and having two young boys with RC cars that all need constant fixing and maintaining I can't justify spending dollars on all top quality components - although I'd love to! So my Hammers is built around as much DIY as I can, as well as affordable upgrades and components.



So some of the first upgrades included metal transmission gears, sway bars front and back, 500K oil in the front diff and DIY rear diff truss. I changed the stock tyres & rims for some generic eBay ones, and also made my own aluminium bell crank steering. Body wise I made some aluminium side panels along with custom stickers and paint, removed the rear tyre and added a scale radiator. I also brought some cheap as chips LEDs and made a light bar on the roof and mounted a couple of lights at the front (I still need to clean up the wiring).



Everything was fine for a while but got the bug for more power, so fitted a 3520kv 4 pole Turnigy Trackstar motor and 80a ESC running 28/78 gearing. Also upgraded the steering servo to a 14kg Turnigy and whilst at it the stock shift servo was replaced with a 8kg Turnigy job.



Suspension wise I'm running the stock lay down shocks in the front, and 110mm Boom racing shocks in the rear connected to aluminium suspension mounts. I think I might undertake a DIY upright shock mod in the future just for the scale look. I found that the stock plastic upper suspension links often bent, so they were replaced with some aluminium ones from boom racing.



Overall I've been pretty happy with the Twin hammers. It's been pretty reliable and it's a great car that is able to be bashed and thrashed, then shifted down to low gear to do some half capable crawling. Just wish they made a gear set that made low gear much much lower!



Thanks for reading. Enjoy the pics!

 

[Dbx]

Looking good. Liking the scatch made bits especially.

 

[Rotare]

Some up dates on my twin hammers. Decided to under take a front upright shock mod using Boom Racing type 1 shocks. All went well for the 5 minutes it ran before one of the shocks unexplainably failed and the shock shaft sheared at the thread. Pretty disappointing since I'd only gone over a few small jumps, but I'm still waiting on a response from Boom Racing to see what they have to say.



As a temporary measure I've fitted the stock rear shocks to the front, limited the stroke and changed out the springs. I'm surprised actually how well this works.



Some other changes include swapping the 3650 3520kv motor running 2S to a 3660 2600kv can running 3S - goes a bit harder now. Also changed the colour and graphics, and since its wet and muddy here modified the tyre tread which made it much more capable.



Some pics before its first run with the upright front shocks.



Cheers.

 

[danvincent999]

Great lookin truck!

Is it possible for you to post pics of the front side without the covers? Im really curious on how u set-up your front sus

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[Rotare]

Great lookin truck!



Is it possible for you to post pics of the front side without the covers? Im really curious on how u set-up your front sus



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Not sure whether this helps you. Currently have fitted the stock rear shocks at the front whilst I'm waiting for replacements for the Boom Racing ones.

 

[Rotare]

In the spirit of DIY I decided to remove the rear locker and undertake the open rear diff mod. Purchased another set of axles and the front diff gear set, along with two 2mm cobalt drills and a bottle of cutting fluid. Did it on my pedestal drill at home and found the first axle easy to drill - I had the hole drilled in 5 seconds! Bizarrely the second one took a heap more time and persistence and I ended up breaking the first drill bit and reckon I wasn't far away from either breaking the second drill bit or giving up! Damn that axle was hard! Finally got it done and reassembled and filled the diff with 500k silicon oil. Overall the mod was a lot easier than I initially anticipated "thumbsup"



It's dark here at the moment and only got to use the car for 5 minutes, but wow, what a difference the open diff makes! Car seems to handle a whole let better and way less prone to roll over. Will post further updates on the mod once I'vve had a chance to use the car a bit more.

 

[Jeff Jenkins sr]

Are you running a locked front diff or is it open also?, why did you opt for so thick of oil in the rear you could get a lot more diff action with thinner fluids.

 

[danvincent999]

I think they would still prefer that semi lock effect if you have the thicker oil.

Just to give it an extra grip during rock crawling or trail running

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[Rotare]

Are you running a locked front diff or is it open also?, why did you opt for so thick of oil in the rear you could get a lot more diff action with thinner fluids.

No front locker.



I still plan to use the car as an all rounder - crawling and high speed. The 500K oil still limits the rear slip enough for crawling, whilst allows the diff to act like an open wheeler when at high speed and on turns. When I first assembled the rear diff with the open diff mod and 500K oil I actually thought 500K wouldn't be thick enough as I could easily hold one rear wheel whilst turning the other.



So an update. Haven't used the car a heap with the open rear diff, but when I did try it (on bitumen) it rolled over considerably less and seemed to handle better also. Turns on a dime now also.



Reason I haven't used it much is because I'm doing some other mods on the car. First one was to make a manual lever to change between high and low gear. Even though I set the end points on the shift servos spot on and regularly they never really lasted too long, so decided a simple way was to make it totally mechanical. I can easily poke my finger into the body and shift between low and high as needed. Kinda looks like a scale gear stick anyways!

Next, to improve handling further I made a custom steering mount and repositioned the steering servo, made a small tray to mount the ESC where the battery tray would normally sit, which allowed me to mount the battery lower next to the transmission.

I also got hold of some firm closed cell foam and made some foams for the tyres.



All the above changes gave further gains in handling and made the car much more stable at speed "thumbsup"



Not satisfied with those mods:ror:, I purchased some Associated B5M arms to fit to the front and am currently working on a solution to replace the front dog bones with CV's to maximise suspension travel.

Also purchased some yeti rear links to extend the wheel base (interested to see if it makes a difference). Just waiting on delivery on some longer upper links and a longer rear drive shaft.

I should stop modifying this car..... but I really enjoy tinkering and trying to improve it "thumbsup"

 

[danvincent999]

No front locker.

I still plan to use the car as an all rounder - crawling and high speed. The 500K oil still limits the rear slip enough for crawling, whilst allows the diff to act like an open wheeler when at high speed and on turns. When I first assembled the rear diff with the open diff mod and 500K oil I actually thought 500K wouldn't be thick enough as I could easily hold one rear wheel whilst turning the other.

Ordered myself a 500k weight... havent tested it yet since I still dont know where to go to have the shaft drilled.

Hows the 500k? Enough? Or still needs more?

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[Dbx]

Reason I haven't used it much is because I'm doing some other mods on the car. First one was to make a manual lever to change between high and low gear.

Next, to improve handling further I made a custom steering mount and repositioned the steering servo, made a small tray to mount the ESC where the battery tray would normally sit, which allowed me to mount the battery lower next to the transmission.

Cool mods there. Loving the 'gear stick' manual shift! Putting the battery down there is a great mod too. Made a big difference to mine.

 

[Rotare]

Ordered myself a 500k weight... havent tested it yet since I still dont know where to go to have the shaft drilled.

Hows the 500k? Enough? Or still needs more?

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I find the 500K fine - for the short time I've actually used the car with the rear diff mod.

The open diff in the rear with 500K is a compromise between a fully locked diff and a fully open one. If you read the numerous posts on the forum regarding the removal of the front locker and filling the front diff with 500K oil, the same pro's and con's of this mod apply to the rear diff.

At the moment I've been enjoying 'bashing' with my Twin Hammers, more so than pure crawling, hence why a lot of the recent changes to my car are focussed on improving handling at speed and reducing the cars tendency to roll over, without losing the cars ability to still be a crawler when needed.

The other upside to having open diffs front and rear is that it reduces the strain & stress on drive shafts, out drives and the gearbox because the diffs provide an amount of 'slip' in the drive train - much like a secondary slipper clutch.

I hope this helps.

 

[danvincent999]

I find the 500K fine - for the short time I've actually used the car with the rear diff mod.

The open diff in the rear with 500K is a compromise between a fully locked diff and a fully open one. If you read the numerous posts on the forum regarding the removal of the front locker and filling the front diff with 500K oil, the same pro's and con's of this mod apply to the rear diff.

At the moment I've been enjoying 'bashing' with my Twin Hammers, more so than pure crawling, hence why a lot of the recent changes to my car are focussed on improving handling at speed and reducing the cars tendency to roll over, without losing the cars ability to still be a crawler when needed.

The other upside to having open diffs front and rear is that it reduces the strain & stress on drive shafts, out drives and the gearbox because the diffs provide an amount of 'slip' in the drive train - much like a secondary slipper clutch.

I hope this helps.

I agree with you on that one. Thats one of the reason y i bought the open diff kit.

1s I have someone who can help me drill the shaft, I shpuld be smiling like you. Hehehe

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[Rotare]

So just finished doing this to my TH.

Tried a cantilever set up with the shocks positioned under the hood, but they were just too big too fit, so I knocked up an up right shock mount from some 6mm sheet I had laying around. The MIP style drive shafts are just the generic type from eBay.



The original intent of adding the B5M front arms was to make the car wider and more stable, more so than improving the suspension travel. I also fitted yeti rear lower suspension arms to increase the wheel base.



..... And although increased suspension travel wasn't what I was after, this is what I ended up with.



Static body position

Under compression

Full droop

From the front.

And the obligatory flex shots

I'm just waiting on a set of 14mm axle wideners to fit on the rear which should make the front and rear width almost identical.



These recent mods, along with the open rear diff has turned the car into an animal. It turns on a dime and is soooo much more stable at speed. Roll overs rarely occur now. With the extra flexibility the crawling seems to be vastly improved too, but I've only done a small amount of crawling so will need to spend some more time on the rocks to say how much more it has improved.



Cheers!

 

[Di_Spencer]

Looks good can you post some pics of how you made the axles work. I am considering doing a similar mod.

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[Rotare]

Looks good can you post some pics of how you made the axles work. I am considering doing a similar mod.



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I'll do my best to explain how it was done



I also purchased some stainless steel pins that had a 5mm shaft. The head was ground down so they would fit snugly and centrally in the out drives.

The stainless pin is welded to the outdrive, a flat is section is filed down on both sides of the shaft so the drive shaft can screw onto it.

Male drive shaft (that has been shortened to suit ) and out drive fit together as shown above.



Stock axle is cut as the dog bone is no longer required. A portion of the female drive shaft is cut and then welded on the remaining portion of the axle which connects to the stock CV.

Male section of drive shaft is connected to the outdrive side, female side of drive shaft is welded to the remaining stock axle with CV joint.

I can't remember exactly what lengths I cut the axles or cut the drive shafts to suit, as I was working on the fly.



Hope this makes sense.