Saturday 19 September 2015

Suspension build up - Front

Progress hasn't been as quick as I anticipated - hence the delay in writing this latest post.
I started by trying to level the chassis. It seemed that one bit would level, and then another bit would be out. I posted a question on the cobra forum and was told not to worry - you'd never get it laser level. I then read a bit further into the build manual and could see once the front wishbones are on you then level across the top wishbone. So on to the next stage - fitting the front wishbones.

I had quite a struggle to fit these. First off my fulcrum bolt wouldn't fit through the chassis tube on one side (on the other it was very tight but went in). I also couldn't see how you could fit 2 spacer washers each side of the chassis tube. I called a fellow builder (Chemicaltrucker) who is slightly ahead of me in the build. He had the same challenge and told me that a bit of emery on the bolts would help, and as for getting the washers in, it is going to be tight and you just have to use a screwdriver to help them in. With this info in hand I had another go and managed to get he bolts and washers in.

The front lower wishbones threw up some different challenges. I managed to fit the right hand side one fairly easily. Bolt went in no problems and this had a 3 and 1 washer combination. However, the lefthand side bolt took 2 hours to get in. Although the bolt fitted in fine, this side needed 4 washers at the front. As the thread of the bolt is narrower than the bolt shaft, this makes it difficult to get the washers onto the bolt. I tried taping up the bolts but this didn't work. To cut a long story short, I got the washers on by initially fitting 3 washers which were easy to move around, and then holding on to the washers, I got a friend to pull the bolt back so I could get the 4th washer in. All looking good, bit of a boost to the build confidence, feeling quite pleased about things. This build is going to be okay I thought......Until I overtightened one of the bolts holding the lower ball joint into the vertical link and snapped it off. I couldn't believe it. The service manual says to torque these to 62NM which I did, and it snapped (On rereading the service manual, I realised that I'd got the wrong torque setting). 
To remove the sheared bolt, I drilled a hole into the bolt and then inserted a screw in bolt extractor. These have a reverse thread and should free the stuck bolt. In my case, the bolt extractor snapped in the bolt. So I now had a stuck bolt with a hardened steel bolt extractor stuck in it - no way this was going to get drilled out. I called Jon at AK as I was thinking I'd need to buy a new vertical. Jon suggested welding a nut to the top of the stuck bolt and then using this to free the bolt. Not having a welder I took it down to my local garage and they were able to free the bolt - result!

Now that I had the wishbones and uprights on I could set the caster angle. I followed the AK manual using the m6 set screw and washer technique. On the passenger side I initially got a caster angle of 9 degrees (see picture with cat in it). I then moved the washers around on the lower wishbone so that there were 3 washers at the front and 1 at the back. This reduce the angle to 7.5 degrees.
On the drivers side I had 7 degrees so didn't need to move any washers. I spoke to Jon and asked if it was okay to have 0.5 degree difference between sides and he said it was okay and you wouldn't notice.
UPDATE: I went back to this a few weeks later and by moving the top washers managed to get 6.9 degrees on the passenger side.

Next I installed the front coil over shocks and power steering assembly - all of which was pretty straight forward. I then installed the front hubs and brake callipers which I'd recently had back from Ed Ward. He did a fantastic job on reconditioning the rusty parts I sent him
It was starting to look more like a car now. You can also see I've started to run the brake lines. I'll cover this in more detail in my next post.