RCknight

iTrader: (5)

Alright what's the public opinion on keying bulkheads on a chassis? Does it help prevent chassis tweaking or does it allow permanent tweaking? What is the census and opinions?

jeff jenkins

iTrader: (84)

If it keeps main components from.shifting during.impact then I would say it prevents tweak.

niznai

I think the main reason is to make sure everything is positioned exactly where it should be just like with matched parts on an engine (e.g. a ported head and its manifold).

Don't think tweak is avoided this way.

jeff jenkins

iTrader: (84)

But if you look at what causes tweak. In my opinion its.parts shifting or moving during impact. Well pining the parts properly in the right locations in theory reduce movement and stay in its origional position . So that is why I feel like it can prevent tweak. At least until the.pins and pin hole develope slop or wear.

RCknight

iTrader: (5)

I like the idea if the pins are large enough and do not bend from impacts. I'm just curious, it seems like a good way to eliminate tweak and I wonder why companies incorporate it. I wonder if it's due to production costs rather than having design issues.

howardcano

iTrader: (37)

Does anyone want to re-visit the subject of laydown or lever shocks/dampers to lower the center of gravity? I think we touched on it previously, but there's probably much more to discuss. Manufacturers seem to have paid much attention to lowering all the other parts of the car, but we still have those huge lumps and their towers sticking way up in the stratosphere.

jlfx car audio

iTrader: (37)

I'm digging the keying of bulkheads think it would be a wise thing to do I hate having to line up bulkheads and check them time after time wile building new kit or replacing chassis
Would also allow the company to claim " the lowest COG in chassis design " lol

heretic

Robitronic did that on their TC but they abandoned it along the way, not sure when, or why . Cost ? Tweak ? I don't know.

http://www.rcinfos.com/2006/2006_02_...0/P1010339.jpg

Tamiya had a super thick chassis for the 415, for foam use. They had some milling/machining under the bulkheads etc, but I think that was for the CG, not to key antyhing.

http://www.tamiyausa.com/product/ite...roduct-id=1011

niznai

Keying requires extra machining hence it can not be cost cutting. I have the Robitronic car and its keys are so tight you can barely push the damn things in (I think they subcontracted manufacturing and didn't get it quite right). A good idea, but with huge costs compared to what they achieve (as far as the buyer is concerned - how much more would you be willing to pay to have bulkheads/suspension holders keyed?). I would like everything keyed, but I am not the market.

As for the shocks and their CG lowering effect, I am not so sure. I think it's not worth the effort. The CG change would be minimal. The extra complication and the inherent slop induced becomes a problem too. Tamiya put the shocks on their M01 chassis flat against the bottom, now that woudl be nice but not easily achievable in a TC. Their M01 chassis/suspension arms was/were so soft it didn't really matter if you had shocks or not, but the idea was innovative and good that way (you can not have shocks lower than that).

Right now I think even bringing the motor out on the side for the sake of lowering the top deck is pointless. I picked up an old Xray T1 and it was wonderful to drive with a stock setup on a carpet with low traction. I think centralising the weight distribution is more important than lowering the CG by a few millimeters and I would even take a punt sooner or later the centralised design the likes of T1 will be back (perhaps along with other improvements).

Right now, to keep the top deck low, I would like to try a centralised design with two spurs (so you don't have to run a belt over the motor) and a saddle pack. I think this would be as close as possible to a perfectly symmetrical weight distribution. I know it brings extra weight but with Lipos we now have a bit of room to move. Torsional rigidity of the chassis is another problem, but I imagine it can be dealt with. Just an experiment I am contemplating. If a company put something like this out, I would buy it.

jeff jenkins

iTrader: (84)

I was thinking more on the lines of actual pins press fitted into the bulkheads which then go into holes drilled in the chassis plates

niznai

Yep, that's what I was thinking too. Still extra machining (and very accurate at that).

heretic

According to the rcinfos article from Nuremberg '06 from which I took the pictures, the top plate also had pins to position itself. I believe we can see one here :

http://www.rcinfos.com/2006/2006_02_...0/P1010335.jpg

Again, they didn't keep it. And I fail to see how it would bring a more precise/reliable alignment than a well manufactured top plate with countersunk holes, or like Xray does, button head screws with a tiny cone under the head.

Xpress

iTrader: (3)

The "tiny cone under the head" screws are not included with the T4. The new kit has plain button head screws.

heretic

oh, I didn't know. Any idea why ?

daleburr

The original Yokomo BD had bulkheads keyed to the chassis.

This is now back for the BD7. All bulkheads and the split suspension mounts are keyed to the chassis, and the shock towers are keyed to the upper bulkheads. Very nice little detail. Would much rather have this that a load of bling like Ti turnbuckles and hingepins.