Engine Mountings

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Engine mountings completed this weekend with the engine set to be two inches below chassis underside. This is a bit more under-hang than I wanted but I may modify my sump to bring that back up a bit. The alternative is to have the engine way too high and have problems getting a bonnet to cover it.

As you can see here I have essentially fabricated a crossmember just like on many RWD cars. The other advantage of this approach is that the extra uprights along tubes J1/2 and F1/2 will allow me to use more effective triangulation in what tends to be a weak spot on the chassis. This will result in greater torsional rigidity which will be important with the V8 engine...

Closeup view of the engine mounting. Note that this is just tacked in place for now, I'll fully weld at the same time as the rest of the chassis. Note also that it is a shadow at the top of the vertical tube, not a badly fitted tube. When I saw the picture I thought I'd made a mistake with the cut of the tube but on closer inspection it is just a shadow...

Reverse view of above. Note that I have welded in crush tubes into the SHS box section so that the bolts can be torqued up without crushing the box section. I may plate the little triangle with 3mm plate later too for extra strength. Also, the plate spanning tubes G and F is made from two thicknesses of 3mm plate (6mm total) which were welded together carefully before adding the uprights.

Overview

Well that's about it for now. I'm busy creating a CAD drawing of my chassis in Solidworks so that I can see how things will go together before I actually weld them from now on...

Gearbox Fitting - Chassis Changes

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Had to take a few steps backwards over the last few days to enable me to make enough room to fit some seats and an engine...

After visiting a fellow Locost V8 builder from a nearby town (Hi Bruce) I decided to rebuild my transmission tunnel to maximise seat room. Bruce managed to keep the tunnel width to a minimum and is still having trouble fitting his seats. My tunnel was 3 inches wider so I'd have ended up with a child's booster cushion for a seat! I also took some advice from Bruce regarding engine space and moved my engine and gearbox 3 inches further back to avoid my crankshaft pulley from impacting my steering rack.

Anyway, the tunnel has now been replaced and is almost complete with just a couple of extra uprights and some fillets to put in place. As you will see from the following pictures, I have also cut out tubes Q and C to allow the gearbox to go back into place. I have also changed the way that the two foremost 'H' tubes attach to Q and C by inclining them. This give more foot room for the driver which was another concern I had previously. Finally, I don't have a photo of it in place but I have modified the standard SD1 gearbox mounting and welded it to a couple of SHS tubes which will span across the tubes 'm' and 'l'

 

View of gearbox in place in modified tunnel

Rear part of tunnel. Just needs another pair of uprights and some cross braces

Here you can see how far back the gearbox is now. The mating face is just 93mm from the front edge of the bulkhead. I also fitted the engine block to establish a level and it looks like I'll have to make do with the sump being 2 inches below chassis rather than the recommended 1 inch. At this level the flat top of the rocker cover is 6.5 inches above the chassis tubes J1/J2 with the SU carbs sticking a good bit further up than that. Ideally I hope to get a Holley or Webber carb setup to avoid having a bonnet bulge the size of Mt. Everest!

Low angle showing transmission tunnel detail. Note how frontmost 'H' upright is sloping towards the gearbox at the top. It has to stay wide at the bottom to clear the clutch slave cylinder bulge. Also note staggered lower tunnel tubes. This is not ideal for strength but I will add in a fillet using 20mm SHS to restore strength. This arrangement was required to allow the standard gearbox mounting to be used and to accommodate the odd shape of the LT77 gearbox whilst maintaining a parallel tunnel width.

Next main development should be engine mountings followed by completion of the rear suspension. I can then turn attention to the front suspension and work towards getting this thing rolling!