machocave

Wow! Cool build Please keep us all posted It's a super interesting project

TomErickson

I do like the B5M front end design. If this pans out I will want to change over to that as well.

Thanks for the detail on the center shaft. I was planning to try the rear center shaft so it's good to know that it will work. I now have a lot of work to do to convert, LOL. Hope to get this done before Saturday and test.

Also I think I will try the C tower on the hub with the stock ball stud position first once I get the motor moved back.

Thanks for all the help everyone!

fredswain

iTrader: (1)

With the standard short driveshaft you still need to run the slipper so that the spring is on the backside. There is just enough room for a shorty. You will need to make a new top deck for it. Here's a picture from when I was initially laying everything out. The B44 chassis is still in this pic but I only had it there to hold the front end on for a picture. I made this top deck. This front end was a B3 since I originally planned on using it's front end. I also have the SC10 front and the X Factory nose piece as well with the B4 parts so I had a few options.I made the top deck.

TomErickson

Thanks for the pic. I tore down the car tonight to check packaging and confirmed your layout. The B44.2 rear shaft is 1mm longer than the original part so I may get one since I need to cut a new chassis plate. Too many wholes in the first car. I agree that a new top deck is required. I am not ready to cut a new chassis yet so I am planning to revert back to rear motor for now. I may go ahead and cut an SC10 chassis and mount the motor as I had it in the current design. With a longer chassis it may just work out. What do you all think? The Team C TM2SC has the motor farther forward with a stick pack along the side.

The only issue with the SC10 is that the half shafts are 2mm too long. I'll need a solution for that to go forward.

TomErickson

I have renewed effort on my upgrades to this project. I am cutting an aluminum chassis to replace the carbon fiber so I can set the motor mount just in front of the Shorty pack which is the most rearward possible. Also I plan to flip the rear tower around and mount the shocks to the rear arms. I will be testing this Saturday. I will post some pics once I get the chassis cut.

TomErickson

I finished the build and now will transition to testing.



The weight distribution feels very good. Once I get the body shell mounted I will weigh the car and post here. The aluminum chassis is a 2.4mm 7075 plate that I custom cut to fit everything including the milled area recess to allow the motor to mount properly. It is not perfect but it is the first prototype. I can see a nice CF 2.5mm plate in the future if this handles well. I did end up fabricating a new rear top deck as was mentioned before.

Body shell is a bit of a challenge. The Team C TM2 and Rudebits DB2 are the same architecture so the bodies may fit fine. I decided to use a C4.2 Centro body to start with since the side pod height was high enough to clear the motor mount. It is too narrow so I will probably find another body shell at some point to improve coverage of ESC and Battery. I should have used my heat gun to form the lexan. I'll add some pics once I get the Body shell complete in a few days.

I also shaved 0.030" off the forward portion of the rear arm to move the arm forward slightly. I read that this was done on B44.2 vehicles for improved forward bite. We'll see as we test and tune.

I need to layout a Set-up sheet now. Should be easy enough cut and paste the AE set-up sheets from the B4.2 and B44.2. This is why I am calling this the B24.2

TomErickson

One decision I had to make was whether to place the shock tower forward or aft of the rear diff. The shock tower mount can be mounted either way and with just a few wholes drilled into the stock arms I could mount the shocks to the rear like many mid motor 4-gear transmissions do. My understanding is that shocks to the rear seem to settle down the twitchy feeling often which is why many 4wd have the shocks forward to increase how reactive the car feels. I hope to test this at some point.

It seems that many mid motor cars that use 4-gear transmissions are forced to locate the shocks off the trailing edge of the rear a-arms (B5M, Centro, X-Factory, and most of the convertible cars do this). To start I decided to stick with stock mounting location with a plan to test the rear mounted shocks.

Krio

iTrader: (159)

Nice! I wonder if a TLR 22-4 body would fit the bill. The profile is roughly the same, would be easier to find, and it might have higher side pods depending on the brand.

TomErickson

I will have to look at the 22-4 body again.

First test session was decent. Weight bias is a challenge for this design. Original build left me with a 60/40 weight bias. This did not do well on the medium to high bite track I was testing on. So I decided to make a drastic change and flip the rear arms and tower to both move the rear wheels forward and shift the weight of the shocks rearward. This worked well but the angle of the CVDs was not optimal and I had the shafts popping out on large jumps.

So I am planning to leave the shocks mounted to the rear and shave the rear arms so that they shift back about 4mm. This should allow me to improve the package and align the CVDs better. I will post photos once I get the modification done. Next testing will be Sunday I suspect.

Thanks for you help Krio!!

TomErickson

After a little brain storming I decided to revert the arms to stock position and shave 2-4mm off the front to move the wheels forward. I will mount the shocks rearward for weight bias reasons. it looks cool as well.

TomErickson

I have one test session under my belt with this design. I had some issues with on power traction exiting corners. My weight bias is not exactly were I would like it at 60.2% Rear/39.8% Front. I would prefer more like 62%/38% in general for medium traction. During trials I decided to flip the rear tower and mount the shocks on the rear of the arms and flip the rear arms. This was complex with the B44 rear design and drastically improved the rear traction since the rear hubs were moved 12mm forward. The geometry was not good for the rear shafts with an increase angle. The shafts were popping out easy.

Given the performance issues I decided to go through the car and really focus on rearward mounted Shocks. With a 12mm change in hub position it was clear that flipping the arms was not going to work well without major modifications. I can now understand why RudeBits used the Kyosho platform for their designs after trials with the Associated platform while developing the DB1. So I reverted the arms back to stock but with more material removed from the arm to allow it to move forward on the hinge pin. I have about 3mm removed and installed plastic shims to take up the gap on the rear side of the arm. Prior to this the rear shock angle and CVD angle were not adequate but now they are fine. I drilled the trailing edge of the arms for shock mount holes. I also added a new hole further inward to stand the shock up for better on power rear traction. Something I plan to test in the next session tomorrow.

I had the revise my body mounts since the rear mount is eliminated when the shock tower is flipped. So far I am very pleased with the results. Shocks are mounted good. Wing mount is rigid enough. I used lexan L bracket strips with servo tape along the sides for a body mount. Seems to be fine.

I removed the 80g stock AE ballast weight and mounted 60g of Tungsten Pinecar weights bolted under the top plate above the outdrive. The goal here was to shift ballast weight more rearward without added aft of the Diff. I am still not at 62% rear bias in the photos below but we'll see how it runs.

Waflet

iTrader: (35)

Hideeho
Your design has just gotten easier...
http://www.redrc.net/2014/04/x-facto...onversion-kit/

TomErickson

Yeah, I think I am done now!! LOL. All I need is about $250 and I can get everything that I want right?

I did determine that I needed to flip the diff to ensure the motor rotation was normal default rotation. Some speedos don't offer the same features in reverse.

I may purchase the X-Factory kit. I have talked with Paul Sinclair about the nose piece components so I can replicate what the UK guys have done. Notice that they have the shocks on the leading edge of the rear arms while I was testing with them on the trailing edge.

Pellefa

Thanks Tom for sharing the evolution of your work, I have followed with great interest!

Just because there is a kit out soon, you might still push development further for tracks with not-so-high grip…

So thanks, highly appreciated!

fredswain

iTrader: (1)

nm