Disaster…

I took the crank up to Andy yesterday to see what he thought. As I was beginning to suspect he reckoned that the #2 and #3 big end journals were toast. This is a real bugger, as you can’t get undersized shells and therefore can’t get the crank reground.

It’s kind of hard to see on the photo, but there’s some quite large grooves in the journal.

So, this crank is not going to work for me. The problem is, what am I going to do about it. Buying a new crank is ridiculously expensive. However, Andy reckons he can get a short engine for a pretty reasonable price. So, I’m leaving it with him for now. Mind you, I’m not sure why short engines exist on the second hand market. Perhaps there’s a chap who goes around bashing in cam covers?

I put all the engine bits on the floor and protected them so that they didn’t get loads of rubbish in them. With that it was on to the next job. First up was to have a massive cleanup around the rear of the car where there’s a lot of general grot and quite a lot of oil that escaped from the cooler when it expired. So, after much spraying of brake cleaner I cleaned a good deal of it up. One problem, though, is that after all the modifications there’s splodges of paint all over the place. All of which is POR-15 which started out as grey but has now gone various shades of greyey green.

One of the things I want to do is to stiffen up the rear of the car somehow, which I think is important. I’ve also been concerned for some time about the way I had to modify the car to get the suspension in the right position. This ultimately required me to locate the top damper mounts above the top of the chassis at the rear. This isn’t a very good idea and in the long run I’d like to completely rebuild the rear of the chassis. However, when I did this to the chassis I included the additional diagonals you can see in the photo here. This is pretty gruesome. It hasn’t fallen apart though.

An alternative I’ve been considering is binding the engine mounting frame into the chassis rather more effectively. You can see this in the next photo where I’ve mounted the engine mounting frame in the chassis. Well, I pushed the bolts into the holes… The idea is to remove those additional diagonals and make a removable section, as a long turnbuckle so I can make it tight, between the suspension turret and the top bar of the mounting frame. Depending on what this looks like I might also add some additional triangulation in the engine bay.

 

9 thoughts on “Disaster…”

  1. I had wondered why you did not have a strut brace across the top of the shock mounts because it did not look like it clashed with any thing but would make things that bit more ridged.

    Looking at the photos have you considered taking the idea you discribe but extending as follows. Mounting the shocks inboard across the top of the brace between the existing top shock mounts and then using a bell crank and push rod. That way you can move the bracket down on top if the chasy rail and you will be able to tie all the unconnected points together.

    hope you can understand my dodgy explanation

    1. Unfortunately, though, a brace straight across doesn’t work because it conflicts with the gear change. Mind you, I’m thinking about sorting that.

      I’ve thought about using pushrods and bellcranks. In fact, I’ve discussed it with Jeremy. In fact, I’ve even drawn it out. My idea was to make a chassis, perhaps a subframe, that was tighter around the engine and diff. I could then make some longer wishbones (I’ve done the suspension calculations as well) and use a bellcrank and pushrod to get the spring rates right.

      Problem is, I just don’t have the time. I did think about it but decided that I just wouldn’t have the time over the winter. As such, I’m just going to make what I’ve got work as well as I can.

  2. for your engine woes. how about throwing it together and filming an engine blow for u tube! the proceeds will help towards a new engine.

    that frame has had some chopping about! could you use it to make a jig to make a new rear end with tubing going sraight to each point.

    as for the suspension keep it simple. longer wishbones sounds better but mount the shocks direct to them. belcranks and linkages will only add flex and backlash. not to mention more construction time.

    whatever you decide to do, good luck;)

    1. Hmm, not sure about a deliberate blowup! 🙂

      The frame isn’t as bad as the photos make it look, although I must admit I was considering sorting it out a bit. To be honest, one of the reasons it’s the slightly odd shape it is is because I originally thought that I’d take the engine out attached to it, which meant that the mounting had to be positioned in a common plane. It’s turned out that you can’t do that, because everything bashed into it. So, it could probably be a simpler shape. Now you’ve made me think of that perhaps I should do it…

      The reason for the pushrods is that if you make the wishbones longer and there’s no structure above the upright (which there wouldn’t be) then you have to incline the springs so much that you get a horrible falling-rate suspension. Hence you need to build some sort of rising rate into the kinematics; bellcranks are by far and away the easiest way to do that. The big advantage of the rockers at the front is that it minimises the falling rate aspect; be a shame to wreck that at the rear…

  3. Thanks for the info, and thanks for a great build diary. its the place i have found most photos of a J15 build.

    1. Thanks. If you need any more photos I’ve got thousands (literally). The vast majority of them don’t make it onto the blog…

  4. I would be interested in seeing a couple of photos of how you have panelled the rear top part of the tub to the frame i.e. along the top of the sills and the same area at the front if you have any photos? Have you considered up loading all the photos and just having some on you-er blog posts

    1. Not sure which bit you mean. Is this the bit in question? If so, there’s nothing special at the front. This is a race car, after all, and sealing is not a bit deal…

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