TOPIC:

Continuing from Eddrick's thread...

I wrote:

...I have just bought a box of Cobra bits from the same guy (I can see his address on the first picture ). I live near Milton Keynes so could pick them up and save on postage.
Looks like a nearly complete rolling chassis - we'll see

Today I spent an hour or so at lunchtime quickly bashing the bits together to see what I've got, and it looks not too bad






If the seller had done this before he listed it, I am sure he would have got more than the 11 quid I paid!
As far as I can tell, it needs:
- metal drive gear in the gearbox - ordered for

Looks a lot better deal than the one I had!

I've got a funny feeling I've got one of those metal gear/shaft thingies in the loft - when I saw the one in my gearbox it spurred the thought "Ah, so that's what that undefined gear belongs to" (I think I aquired it whilst searching for cheap gear blanks to repair my Hilux gearbox, yes the intermediate transfer gear). I'll have to have a dig & see if I can find it (Assuming it didn't get used for something else!)

Definately got a spare diff - bought it to help me design the ball-diff for that old home-made 1/12th car I built ages ago.

I know I keep plugging them but, have a look on Kamtec's site for a body - I don't think they do a Cobra, but I'm sure they do an Optima Mid repro, which looks very similar (To me anyway!)

Definately haven't got front wheels
Rear springs - generic ones would do I'm sure!
No fasteners - gave all I had to my bro (In disgust at their slotted heads!)
Pinions - standard are 32DP, if fitting the slipper you need 48DP. Number of teeth, Jonny's your man, but I'll tell you now, whatever the standard pinion is, it's too small (I'd say go 2 teeth bigger if using 32DP & silvercan, on the assumption mine was standard).

One more thing, I'd suggest that if you plan to use an MSC, you need to ditch the Mardave one & use a Tamiya - the PCB tracks are way too thin & will burn through if you stall the motor. The pickups are a nuisance too once they start to wear.

& yet one more thing... if you haven't got posts to mount the steering servo, get some - I found the leverage from the steering setup too great for servo tape to cope with. Not sure if they're supposed to have servo-mounting posts, but the holes in my chassis were already there so I made some

lol. yes we are all old geeks who want to watch hairy porn.....

We'll get rid of spam like that as soon as we spot it...
I like vintage but not the hairy kind.

I have that feeling that I've missed something....

eddrick wrote:

I have that feeling that I've missed something....

Porn spam ... I guess you know your thread's popular when it gets hit ... none of mine have

eddrick wrote:

...
No fasteners - gave all I had to my bro (In disgust at their slotted heads!)
...

What screws did you use to replace the self-tappers? M2.5, M3, something else?

I didn't replace them in the end, I had enough kicking about to make up a full set of slotted to keep it as original as I could.

If I ever get one for myself I'd probably replace the screws with generic phillips-head self tappers (Like late Tamiya ones) as they're easier to match with fasteners with other thread forms.
I don't like using machine threads in plastic if I can avoid it, but if I had to for the Mardave, M3 would be closest. You're likely to have a struggle on your hands trying to source M2.5, but if you need some, best places to look would be Maplin, RS, electronics specialists or talk to your local fastener/engineering supplier. OR replace with the nearest "Ba" size from a model shop.

If you opt to keep with the slotted theme, it would be worth looking in places like Wilkinsons, B+Q, Homebase, Screwfix (Or RSwww.com) etc for packs of small wood screws. Be aware that they're usually specified with imperial sizes though (eg "No.4 x 1/2" etc) & asking for "3mm self-tapping screws" will probably just get you some hummy looks & clueless responses. Better still, take a screw with you to match - "Please can I have some like this"
Also note that for some bizarre reason, pozidrive & slotted heads are commonplace with stainless self-tappers, I guess to fit in with the imperial only sizes of stainless materials (Same goes for aluminium)

The metal drive gear arrived today, so I have popped it in the box just to make sure it all turns OK. I'll dismantle it again and clean it later.
Had a look at the slipper assembly. I think it is all there, but the old metal shaft has snapped off at the cross pin and is still stuck in the metal top hat thing.




In the second picture, you can see the pin, but that was stuck fast too. I was beginning to suspect it had be stud-locked or superglued in place.
The shaft would not budge in either direction.
So I fitted a M2.5 nut to the threaded end and started to tighten it as much as I dare. There was a "pop" and the nut went loose. It has either moved or sheared the thread.
However all was well and it came apart.


Slipper fitted.

I know the Mardave slipper is pants, but it will do for now and I will probably lock it up solid anyway.

Looking at the second picture, you can just see that the pin is being held in place on one side by the end of the shaft (the cross hole is not completely open). However this does not explain why it would not move the other way - must not have been hitting it hard enough I 'spose
The teeth on the gear look a bit worn, so we will see how it runs.
I had a look at one of my (many ) SRB spur gears and the 70T one is a similar size to the mardave gear. If I could find a sleeve with I/D 4mm and O/D 5mm I think it would be quite easy to fit. Any brass/ally tube in that size?

@JR - what pinion will I need with this gear for a silvercan motor? Good acceleration/battery life. Not too worried about top speed.