Corally Rear Wheel Bolts M2.5 !!!!

When I first built my "US Spec" Corally SP12X, I was expecting to fit standard 1/12th wheels with standard imperial bolts. This was not to be the case.

Corally are pasionate about doing this all in metric like the true Europeans they are.... as a result you are going to have to find metric M2.5 hex bolts to secure your wheels to diff and offside hubs.... these are as rare as rocking horse poo and they were ommitted from my kit! Argh!

Tip Number 1. The bolts used on standard brushed motor end bells are M2.6 and these will do the job in an emergency (thanks Pete).

Tip Number 2. I get my M2.5 screws from here http://stores.ebay.co.uk/stainlessbolts

They do 8mm ones but it is REALLY important that you file them down to 7mm long (threaded part) and no longer. If the screws are too long they do through the hub on the diff side and collide with the diff ring which will really mess up your diff action!

Corally SP12X Diff Nut Trick

I have noticed a few people suffering from the diff nut coming loose on the SP12X. Unlike other diffs, the Corally uses a carbon nut on a carbon threaded shaft. There is no lock nut as such and the location of the diff nut is reliant on the nut/thread friction and the grip offered by the serrated locking washer.


The Corally diff is one of the best I have used with a great smooth and reliable action provided by the outer thrust race that comes as standard. I have a tip here that will solve or prevent the diff nut coming loose. Before we start be warned!!!!

Warning 1. The tiny thrust race balls are NOT captive within the spacer and its "game over" if these go on the carpet!

Warning 2. I am going to do stuff with superglue, fingers, carbon parts and tissue paper. We need to make sure that all 4 of these components are separate at the end of the process.

Step 1. Read Warning (1) above and strip your diff down. We want the shaft.

Step 2. Place a small drop of super glue on the threaded part of the shaft and then quickly and evenly wipe it into the thread with tissue paper, forming a smooth and thin (very thin) layer coating of super glue over the thread. Do not allow super glue to touch the non threaded parts of the shaft.






We are not looking to fill up the thread groves with glue here. The objective is to use the glue coating to slightly oversize the thread.

I used a standard viscous super glue off the DIY shop shelf. I would worry about the "Orion" type of watery thin cyano that is popular for mounting rubber tyres. Introduce a drop of this and it can capillary itself all over the the thread, the shaft, your car, your fingers and the work table! That's Warning (3).

Step 3. Wait Wait WAIT for the glue coating to fully dry before you try the nut on the thread. You really do not want to superglue the nut to the shaft here! Try the nut on the shaft, it will now feel tighter. Ideally you want it to fell tight enough to be difficult to turn using your fingers alone but easy with your diff spanner. I repeated step 2 a couple of times until my nut was "locky" enough.

Step 4. You may now find the spur gear bearing will not pass over the thread as you have slightly increased the outer diameter with the super glue coating. This is easy to rectify. Just rotate the shaft by hand while holding the thread with some fine abrasive paper wrapped around it. This will remove some of the super glue and reduce the outer diameter of the shaft whilst keeping the coating in the thread groves.

Job done!

A final tip. I alway loosen the diff off after the end of a meeting. This prevents the O ring being over squashed and distorted.

Cheers


Mark

SP12X T-Bar Setup

Credit for this info to Peter Winton and Roger Manwaring

OK.... the T bar that comes in the Corally SP12X kit as standard is a 2mm piece. This is the one I think most people run in the UK on our "medium bite" carpet conditions but with two minor deviations.

Firstly the more recent Corally 2mm Tbars were strengthened which made them slightly stiffer. I am advising that you modify the T bar by filing away some of the material as shown in black on the following pictures. You can see below with one side only done to reveal the difference.

I use a set of small "diamond" grit files to do this (get them from most craft shops) as carbon and glass fibre ruins carbon steel tools. Keep the curve libe in the T bar as shown so as to not introduce a stress point.

Secondly, when you install the T bar, do not use the glass fibre spacer that comes in the kit. Use two washers of 1.6mm thickness or chop the little round ends off the spacer supplied in the kit to make the "washers". The idea is to keep a little more flex in the rear part of the T-Bar.

Also DO NOT install the centre screw. This stops the flex we want and I have seen the centre screw wreck the motor pod carbon under tray when and if the T-Bar breaks in a crash. Leave it out!

Photo on the left above shows the centre screw out.

Photo on the right. Two spare parts that all SP12X drivers should carry! Mine are as yet unused ;-)

Corally SP12X : Front End

Corally SP12X and the Associated Front End

In the UK we pretty much all use the Associated (AE) front end on the Corally SP12X. To be honest, I have never run the Corally one that comes in the box, pretty as it is! If the AE is what the World Champion uses then thats good enough for me!

I had enough Associated bits left over to build a front end up but you can now purchase the complete front end conversion kit from Corally as a "blueprinted" set. The part number for this is 75950 and its called the "12X WC Front suspension conversion kit". More details are here:

http://international.corally.com/news/news.htm

The chassis is predrilled to take the AE front arms so you will have no problems here.

You do have to drill two new servo mount holes in the chassis 8mm back from the rearmost set that are drilled as standard. To do this you will want a sharp 3mm drill and countersink bit. Remember carbon fibre really kills cutting tools!

The exact lateral (sideways!) location of the holes depends on the servo you use. Try to leave the servo mount posts a little wide (by say 2mm) so you can adjust the servo position to get it exactly in the centre. Think and double check yourself. It is important the the servo drive spline ends up crack on the centre line of the car.

If you need good instructions on how to build an AE front end accurately, you will find then in this blog... read on.