Friday 30 August 2013

Days 9 & 10 (Full days)

I've been really busy trying to get as much of the car done before the weekend arrives so this post is long overdue. With Engine, Gearbox and Diff all in and the cooling pipework all sorted in the engine bay, the last couple of days have been all about the derriere (not mine!). Here's what i've been up to and the order I elected to do it in.

Dedion Tube

This was the obvious starting point. The tube is all one piece and has 'ears' which attach to each end which later become what the drive shaft pops out of and the rear calipers attach to. the first job is to attach to brake lines to the Dedion itself. A right and left are supplied for you in the kit and you need to rivet them in place, 2 rivets one side, 3 the other. You then mount a 3 way union to the back of the tube which the lines connect into. You then connect your last remaining flexible brake hose to the top of the union and you are then ready to fit it to the car.

Unfortunately no pictures of me doing this but I found the best technique was to pass the tube in (from RH side) rotating it so it would go underneath the diff and then, having popped out the other side, rotated and lifted over the chassis rails on the far side. So far so good, I had the tube lying just behind the diff, resting on the chassis tubes which I had duly covered in foam pipe insulation to stop it marking.

Rear Radius Arms

I then fitted the rear radius arms to the car. This was quite straight forward although it took me a while to work out what orientation to fit them. I even fitted one back to front initially (oops). The large bush goes at the Dedion end, narrower one on the mounting point towards the front of the car and you will find indents 'wasted edges' on the sides of the radius arms. This gives extra clearance for the caliper once fitted so make sure those are outmost.

There are actually 2 mounting points that you can choose. 'Comfort' is the higher one of the two, the lower one being more 'handling' focussed. I opted for the latter which left the radius arm tightened up and running perpendicular to the ground. I then fitted the bolt to the mounting point on the Dedion. No problems there.

Rear Radius arm bolted in

Rear ARB

I then moved on to the Rear anti-roll bar. The first stage is to get the supplied bushes on to the roll bar itself. The guide tells you to apply rubber lubricant at this point and to slide the bush down the flat part of the bar, around the corner and onto the main tube. What it fails to mention is that this is rather like being told to pull your lower lip over your forehead! Its got quite a bend to go around.

The problem

In the end i found a solution which seemed to work pretty well. Just remember to coat both the bush and the ARB in rubber lubricant to make sure everything slides nicely. Use a screwdriver to lever the bush around the corner, they are quite tough but have plenty of stretch.

The solution
The ARB is bolted to the lower chassis rail using the supplied aluminum fitting. Its exactly the same system as that used for the ARB

Rear ARB mounting point

A Frame

I grabbed this out of the box and thought yeah, this one will be on in 5 minutes. WRONG. This job took me a fair old while. Initially I started off by attaching the middle part of the A Frame to the mounting point on the Dedion tube. I got half way to 'drifting' the bolt through when I realised I hadn't put any copper slip on it, It was already a tight fit and trying to get it to come back out was really hard work. It was equally hard to get the bolt back through again and in the end it required some assistance from my better half who kindly pushed against the join with her foot from the far side of the car so that we could stop it from moving whilst I hit the bolt through from the other side. Anyway eventually it went through and I then moved on to the other 2 mounting points. At this point the guide uses the words 'centralise' and as soon as you read it you know you are in for the same difficulties as you had with the diff earlier in the build process and sure enough its near enough the same process. You have to use large washers to get the A frame (and the Dedion which is attached to it at this point) centralised. In my case I got quite fortunate as it ended up being an equal number of washers either side to get the tube within 1mm of being completely central.

Washers in place
Having done this both sides, I then had a quick look to see how close the Dedion actually is to the diff and the answer is very close indeed. Without the suspension attached at this point, I was able to move the Dedion up through its full range of travel to see at what point it would touch. The suspension would have to compress quite a way before this happens but it could conceivably happen under large compression. I'm interested to see what amendments Caterham have come up with to combat this as I can't see how anything other than a completely revised plate would solve it. We shall see...

Tight, very!

Drive Shafts

I then had a go at fitting the drive shafts. These are actually different lengths as the shape of the diff is such that the distance to the hubs is longer on one side of the car to the other. Before they can be fitted, the covering plates on the BMW diff had to be removed. A quick check with Derek at the factory confirmed that these were not to be used in anyway so it was OK to 'take to it with a screwdriver' so thats what I did. The shots below show the covers mid way through removal and then completely removed

Diff covers before removal
Mid removal

After removal

Before i stuck the drive shafts in I took a shot of what the diff looked like inside. I remember seeing a forum post some while ago saying that the type of LSD fitted to the diff could be identified from the patern inside. No idea where i read it but now that I can see what this looks like I'll be sure to dig the article out again and see if I can work it out.

LSD Inside the Diff

To fit the drive shafts, I lightly greased the ends and they slotted right in.

Gently does it

Drive Shaft push fitted into place

Dedion Ears and Hubs

I then moved on to fitting the Dedion ears to the ends of the tube. Straightforward enough once you know how although I did have to give Derek a call at the factory to confirm which bolts to use. I think the fastner packs have had a recent update and so unfortunately, where the guide tells you to use bolt (5) it is in fact bolt (6). With that all cleared up on went the ears. 2 bolts secure the ears to the Dedion, you then have 4 more bolts which are used to secure the hubs to the ears. Nuts behind the ears secured the whole thing in place.

Top Down view of Dedion Ears with Hubs attached

At this point the whole thing was nice and stable and with the suspension struts not currently fitted to the car, I took the opportunity to fit the roll bar.

FIA Roll Bar

I'd head from another 7 owner (and indeed the guide also tells you this) that you can't fit the FIA bar once the suspension dampers are in place. This is because you have to pass a bolt up through and into the roll bar from underneath, right where the suspension top mounts would be if you have them fitted.

The bar was simple enough to fit once I'd found the correct fastener pack although where the bar attaches to the rear of the boot, the bolts needed a bit of gentle persuasion to get them to go through. I really am extremely happy I purchased a soft faced hammer. It's seen a lot of action and has been great.

Rear Dampers

With the roll bar in, I then went back to fit the rear dampers. These were quite straightforward to do save for the balancing act that I had to do because I was doing it single handedly. The struts attach at the top by way of a bolt that passes through from behind where the backs of the seats would be in the interior. A straightforward 2 man job but tricky on your own as you need to line everything up by eye and then, whilst holding the strut in place, contort yourself round into the interior to try and get the bolt through. A light tap with the soft faced hammer helped here.

Shot of rear suspension needed

Drop links

The drop links supplied need to be fixed to the Rear ARB. This is straightforward enough but unfortunately I ended up breaking one of them during fitting. The link comes with two copper/brass coloured nuts at either end. One is re-used to provide a locking nut when attaching the large hexagonal spacing. At the other end (where it attaches to the roll bar), you are supposed to use the nyloc nut supplied in the fastener pack. Unfortunayely I used the supplied nut in error, threaded it and now can't remove it or do it up! I'll have to hacksaw it off completely tomorrow and await the replacement I have just ordered of the Caterham website (oops)

Drop Links to ARB

Rear Discs and Calipers 

The disks were simple enough, slide them into the hubs (they are splined) and then duly do the whole lot up using a HUGE nut. Luckily I had a 41mm socket for this, it's massive. For now, the whole lot has been torqued up to about 100 NM. Eventually I need to get this to a whopping 280 NM but I can't do that at the moment as the whole hub moves under that sort of force. Final adjustment will have to wait until the brakes have been bled and the force of the brakes can hold the whole thing still.

The rear calipers were then put on the car. Took me a while to get the orientation right but otherwise fine. I also fitted the pads at this point and I found the best method was to fit part of the caliper to the Ears then slide the pads in and then fit the bigger part of the caliper over the whole thing and then bolt it all together. Again remember the Copper Slip!

Pads fitted to 1 half of the Caliper
I've shown a picture of the bolts that attach both parts of the caliper together. I was looking through the fastener pack to try and find bolts that would work and then suddenly realised the bolts were in the boxes the calipers had arrived in - Duh!

Here is a shot of the whole thing once it had all gone together. You can see the handbrake cable has also been routed to the caliper and attached. I found getting the end of the cable over the clip on the caliper rather tricky. Loosening off the cable by winding the handbrake adjuster (white plastic thing mounted to diff) back helped with this process as did removing the spring temporarily on the caliper (copper bit shown below)

Brake Assembly

All I need to do now is see If I can find some guidance on how to finally attach the brake line to the caliper. At the moment the pipe is siting at completely the wrong orientation to get it to fit onto the calipers connection. Not sure If I'm supposed to lightly bend it into place but I'm sure a bit of investigation and I'll have it worked out.

Starting to look like a real car now, not long before I move on to doing the interior.

Coming along nicely


  1. Looking good. Would be interested to hear how you get with the rear ARB on the road. I assembled it exactly as you have, but found there was a metal knocking noise (which you could feel through the seat) when driving over bumps. I think it was either the droplinks hitting the ARB edge, or the centre of the ARB hitting the diff, but removing the ARB altogether cured the problem. Car feels fine without it - possibly slightly looser at the back, which is nice!

  2. Hmm interesting, well I will be sure to keep you posted once I have it on the road. Did you try any of the other positions on the Anti Roll bar? At the moment I have it in the lowest hole which is apparently the most gentle of the settings.