Wednesday, October 27, 2010

McArlus Cars - 10

I have started assembly all of the bolt on bits to the newly painted chassis, which is really quite fun actually, but more on that shortly.
In the meantime, I have cleaned up the spare engine that I will use and take the opportunity while it is still out to do some work on the clutch, before it is installed for, I hope, for the last time!
Ever since I started the first car, about a million years ago, I had been concerned about the clutch. Initially I was worried that a clutch that was designed to carry a 250-300kg motorbike and rider would struggle with a 550kg car and driver, particularly as were now driving two 7” race Tyres and not one relatively narrow motorbike tyre. Standing starts were always a worry.
Fortunately it appears that Honda have built in a fantastic margin for error in the clutch and it has proved to be most reliable. The only trouble has been due to my own doing.
In the yellow car I used a quality car engine oil in the engine, forgetting that the clutch is also running in the same oil. After about 12 months of use some clutch slip started to creep in, mostly with an over  rev as each gear was changed up.
Initially I feared the worst and that we were in for a constant clutch issue, but since chaging the oil, clutch springs and friction plates (which had been soaked in the wrong oil) I have never had any more trouble.
So in the picturews you can see the cltch plates and springs.
The new springs are on the RHS and are advertised as being about 10% stiffer that the standard LHS spring. That may be an issue on a bike hand clutch , but has been fine on our foot clutch.  I check these on my trusty bathroom scales not so much for accuracy, but to at least compare the springs. There is nothing worse than changing a failing part with one that I inferior!
By clamping the cross piece of steel onto the two blocks on each side it is easy to compare two springs at the same compression.
The standard springs read 16kg and the new springs read 20kg.
You can also see in the picture the discoloration on the steel plate on the LHS. This plate was quite blue and had clearly been overheated. Compare it to the new plate in the middle. The overheating is possibly not caused by us but may have been, because it is second hand engine, but I have replaced all 9(!) of these plates any way.
I also replaced the 10! Friction plates (RHS of photo) as these had been soaked in the wrong oil, although they still had plenty of friction I didn’t think it was worth the risk.
Hopefully the clutch will now be fine, so I will install the engine and shoulid have a complete rolling cahssis by the end of this lkong Cup weekend.
Lots of assembly happening now. More on that soon.

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