Interesting read that was, as like others I'm going to try and get the cobra and a old astute ready to take on the world again, the astute is coming nicely but realistically it will never race. The cobra build not so much :( but stands a better chance when finished.
I'll pm you for some details if you can help that would be great :)

Restoring my Cobra
 

Hi,

New to the forum but spent a lot of time reading through this thread and got the itch to restore my Cobra. I now live in the US which makes getting parts a little tricky. The original shocks leaked, couldn't get them fixed so replaced with some 3 Racing although reused the original shock mounts at the bottom. Replaced the tires with Proline Dirt Hawgs and added a mild brushless setup we'll see how long the diff lasts :D

Really interested in the B4/B3 mod to fix the slipping diff if anyone has any success and some steps on how it's done I'd be very interested in it!

Photos:
https://plus.google.com/photos/11734...IfYorb22NjaoQE

Also links to original manual and exploded diagram:
https://drive.google.com/file/d/0B7o...ew?usp=sharing
https://drive.google.com/file/d/0B7o...ew?usp=sharing

Hey up Rooford,welcome to the Cobra/CobRat/Cobra-ish fiddler's den.

Your best bet for the B2/B3 gearbox mod is to pm Adey.

He came up with it,engineered it and tested it all to the good.

With mine I just got shot of the chocolate Mardave'box and fitted a Mad Rat onto it,miles better.
I couldn't get the Mardave diff to play with just a 25 year old Parma
Cyclone 27t super stock in it.
It'd last a couple of minutes(well,seconds really),come undone and
slip it's naughty bits off.

The Rat'box has transformed it from nearly going into the trash to
a pretty competent and fun dirt car.

Just got my hands on pair of RC10B3 3-3 rear arm mounts and a pair of composite B3 rear arms for the next bit of modding.

Having got the whole shebang to drive nicely,go where I point it and do the odd party trick(opposite lock slides,drifts,etc),I find that the screws are pulling out of the rear
mounts that were cut from the original Cobra gearbox.

The B3's 3-3's and rear arms should make the back end tougher plus keep the toe-in
and add some decent anti-squat.

Hey Miggers,

Interested to see how you mod the B3 arms.

I couldn't get the original gearbox to work with my brushless setup, it was stock with no slipper clutch so not surprising that the diff slipped. Tried fitting the B4 outdrives to the original diff, but they made the original diff too wide and the original gearbox didn't go back together so went with the MadRat graft mod.

Took me two attempts, original gearbox was cut wrong, but I learnt a lot from that first attempt. Fortunately Mardave still sell the gearbox so I had a second chance to get it right.

The new gearbox sits inside the old gearbox, I used a Dremel to grind away parts from the old and new gear box to get a good fit.

So far it's working pretty well, I drilled the original chassis and bolted the old gearbox and new gearbox together which held the back pretty securely. To hold the front of the new gearbox in place I drilled two holes in the old gearbox which lined up with the original gear box front mounts using a rod inserted through the whole assembly to hold the front in place.

My Cobra has some play in the front wheels and rear. When reversing it can sway backwards and forwards, is this normal and if not anything which can be done to fix it?

Like the idea of the rod.Mine has a custom machined alloy block at the front that uses
the Rat box front holes and then is bolted to the chassis.

I found that the suspension mounting on what was left of the Cobra box far too wobbly as was,so that was why I then went for a custom alloy mount and homebrewed alloy rear shock tower.

Much firmer and it allows the shocks/springs to do what they should.

As you've seen,mine also has a complete B3 front end on it with a custom top brace.
No wobbles or play and it goes where I want it to.

I have a B3 manual downloaded and the dimensions for the hole spacing for the B3 3-3's,so it's a matter
of stripping the back end down,marking,drilling and fitting,then take the chassis to work and get
all the not needed holes welded up.

Yep suspension mount isn't as firm as I'd like it. We'll see how it holds up, if not I may well be bugging you about home brew alloy mount.

While I've got a few spare wheels I don't have any spare axels or wheel screws. Are you running the stock axels or have you modified those too?

Quite enjoying getting this running again, definitely has some pep with a brushless setup and a lipo pack really makes it fly. I wonder how far off the pace it is, I might be tempted to try a local track but there's more risk of breaking something and spares aren't so easy to come by.

Hi Guys, not sure if any of you are interested but I have two Mardave Cobra's that I'm looking to sell, can send pictures of them both.

Pm me with your email address for pictures to be sent.

Richard

B3 front axles,Cobra rears.Like I said,the front end except for the steering
arms and upper brace is all B3.


I should get to measure up and re-drill the chassis sometime this week,then narrow the rear end
down ready to re-fit the 'box,3-3's and arms.
One of the boys at work has already welded up all the so far unwanted holes,it was like a Swiss cheese
at the front end where I'd test fitted various steering/front end set-ups in the past.

Just waiting for the DEX 410 rear suspension tower to arrive,I'll knock up a mounting bracket for it at work
and then post ya'll some pics of the B3 back end mods.
The chassis is fully welded up,drilled,painted and once I've made a mount for the DEX410 tower,ready for re-assembly.
Ooh yeh,got to get the drive shafts welded up too.

For those that really want to know,the DEX410 rear tower arrived,a mounting was made up and fitted,the Cobrat is now back on it's feet.Man,it looks w-i-d-e.

The motor and other electrics(though the steering servo is in place)need to be fitted,so it's sitting way high on it's suspension,but with the body and wing dropped on,it looks great.

I'll post some pics up of the mods needed to fit the B3's 3-3's and suspension arms
together with some general pics ASAP.

Here we go:
Spot the difference
http://i91.photobucket.com/albums/k3...ps6t5xlf6n.jpg

http://i91.photobucket.com/albums/k3...psjdcyv4t1.jpg

Back end o't'chassis,cut narrower,shorter and drilled to take the 3-3's
http://i91.photobucket.com/albums/k3...psnrsgeeko.jpg

Just in case anyone says that ain't a Cobra chassis:
http://i91.photobucket.com/albums/k3...psbgy7elzt.jpg
Oh yes it is:
http://i91.photobucket.com/albums/k3...psmen0tbhj.jpg

Wingless shot
http://i91.photobucket.com/albums/k3...ps5crwtwvy.jpg

Close up of 3-3/'Ratbox interface:
http://i91.photobucket.com/albums/k3...ps6puwlcd2.jpg

If anyone needs more info or pix then just shout up.

Hi guys,i’m looking at replacing the slipper clutch spring washers on my cobra,can anyone recommend where i could find replacements?? Does anyone know of a spring that could replace these washers??
Thanks Mark.

Thanks,but i only need the spring washers or a suitable spring.
Does anyone know of any period mods to help try and improve the slipper clutch?

I think the tlr one fits. You need to speak to Adey who has posted on this thread before. He did loads to the cobra to make it competitive and his car is pretty much the ultimate cobra in terms of mods and upgrades. I maybe wrong but I think his car was the car used by mardave for development work some years ago.

sorry to resurrect an old method of modding this gear box but I just wanted to check that this was really as simple as fitting a new bush in the mardave diff gear and fitting B4 diff parts?


The Outdrive bearings need modifying it seems? Is it possible to order correct sized bearings to fit from someone?



so I'd just need these parts and to look at the idler gear and bearings as well to go brushless?



https://wheelspinmodels.co.uk/i/24592/
https://wheelspinmodels.co.uk/i/24591/
https://wheelspinmodels.co.uk/i/24590/

I had a look around,but couldn’t find any suitable bearings to do the job,so you still need to do the mods to the associated diff outdrives.

I still get asked a fair bit about my cobra. It’s currently in bits in the cupboard and hasn’t been used in years. I’ll put it back together and run it or sell it. The bearings can be obtained from a bearing supplier. I modified my outdrives to accept b4 diff plates and thrust bearing but because my diff halves were cobra se ones they were too soft and needed replacing every few meetings so I then used b4 diff halves. I managed to get a good reliable gearbox eventually but then needed to find new driveshafts as they became the weak link. I used tamiya ones. All mods were done to make the car brushless friendly as mardave were planning a new cobra called the cobra evo which was to replace the cobra se. Take it from me, if you want a cobra to modify and race you need an early car like the cobra tq. The diff halves were much harder and the alloy chassis is made better than the cobra se chassis.

like to fit a lipo
 

Any tips on fitting a lipo in a Mardave Cobra please?

Mine just slots in between the original stick pack holders and sits lengthwise
in the chassis.