Some back end decisions made

I'm behind on the blog... some of this was taken just after my last post and I'm just getting to it now. I also need to take some more pics. I've tacked in a few more tubes but I haven't taken any photos of it.



I bought the rear sub-frame home from the storage shed. I spun the frame around and put the entire rear subframe up on the table to see how it fits.



The back rail you can see on the left is the seat back of the car. The wheel is in its current position is about 200mm back from where the wheels would be if built by "the book". As you can see there is quite a bit of the sub-frame protruding into what should be the cabin. Main issue is the mount points at the bottom and the top cross member that the front diff mounts attach to.



Another picture of the top rail protruding in passed the seat back.



How the dif mounts at the front.



Another view of how the dif mounts



I removed the dif from the subframe so it was a little easier to move around (sub-frame with everything attached is heavy).



So I decided that I could cut off the front mounts and the top cross member. That way I could use the sub-frame and keep the rear wheels as far forward as possible. I was still a little worried that the wheels would be too far back and wouldn't look right. So I bought some cardboard and mocked up the outside shell of the car to get a feel for what it would look like.



After getting a feel for what the car would look like I thought pushing the rear wheels back would still look pretty good. So I decided to start major surgery on the sub-frame.



I took the sawzall to the to the top and cut it out. I took measurement before cutting it out so I can manfacture new front differential mounts.



Here's the subframe with the top tube cut out.



I marked up the cut of the front mounts and took the sawzall to it as well.



And after the sawzall has done its work.



And the other side.



Lining up the sub frame I tried to take as many measurement as I could so the sub-frame would be centred and square.



To get a good weld surface I cut a birds mouth in the tubes.



Another picture of the joint. I also welded a plate to the front but I didn't take a picture in detail of it.



At the top of the sub-frame I also cut a birds mouth to get a good weld area.



I took a wire brush to the area to clean off the black paint for welding.



Here it is with the the middle seat back tube mocked in place. The fit was pretty good. I also took all the subspension components off the sub-frame. After I was fine with the position of everything I took it all off. Made the job of measuring moving and cutting much easier when it is light enough to easily pick up.



A close up of the tube mocked in place.

So since these photos I've tacked it all in place. I've added a couple more brace tubes to the front of the frame, I added bracing in the seat back and I put a brace out to the sub-frame.

I put the differential back in so I could start the transmission tunnel. Got the first tubes in the seat back area tacked in place. I need to pull the engine out from under the construction table and start some detailed measurements for the transmission tunnel. I want to maximise the pedal box area as it will be pretty tight down there. The seating area is pretty narrow too. I was thinking about trying to sneek an inch or so extra room but I think I'll play it safe and go with the book dimension on it. A bit of movement in the differential on the rubber mounts without enough clearance wouldn't be good.

I put one side of the suspension back on and picked up the rear shocks from the storage shed. I'm still faced with 2 problems at the back.
1) I need to work out how to build the space frame for the back making sure I have clearance for the shocks which are mounted at the back of the subframe.
2) I was thinking of using the standard shocks for the back. But the weight of the car will be much less (so they may be too hard) and I have to work out mounting points. I was thinking I might try a push rod style suspension at the back. Put a pivot at the top of the subframe and mount the shock down to the rear cross-member of the sub-frame. I hadn't planned on doing push rod suspension but I might give it a go. I have to keep in mind I need room for a fuel tank somewhere at the back and it might be nice to at least have some storage space.

So I think the next little while will be me noodling on the rear suspension and measuring out the engine and transmission in detail for the transmission tunnel and engine mounts.

I still haven't done any more on the front suspension. I think I have picked what I want. I might try modeling my suspension in a software package that looked OK and not too expensive just to make sure its not terrible. I know I won't be able to manfacture it to the millimeter that I can model it to and that frames twists, tires deform etc.. I'm just looking to make sure that it is decent.

Frame continues

The build has been coming along quite nicely. A few things have happened lately.

I had an electrician come out just after Christmas and he put 3 new 20 amp circuits in the garage which has been great. I can have heat on, welder and run tools etc without worrying about whether I'm going to trip the breaker.

I also did a bit of a home insulation job on the garage door. So far it seems to be doing the job although we haven't had many cold days to try it out. I put the heat on to take the chill out of the air in the garage and it seems to stay reasonably comfortable. Hoping to continue to be able to work through the winter.

Now to the car. I've manage to get pretty much the full front of the frame tacked together. The only pieces I haven't tacked into place are the pieces around the transmission at the front. I need to get in and do some detailed measurements of the engine and transmission to get as much space for foot room as I can.

The frame tacked together from a couple of days ago. I've added side diagonal bracing since then.

At the back of the car I'm also up to the point where I need to decide what I'm going to do for the back-end. I've got 3 options that I'm considering.

1) Modify and weld in the S2000 rear subframe to the frame I've built to date. It is probably a heavy option but it should also save me a lot of time and its a proven rear end set-up. I've seen someone mid-build doing the same thing on another build site but I'm quickly catching up to where he is at and it isn't finished.

2) Create my own rear frame to accept the S2000 components. I'd replicate the geometry but using my own frame. Probably lighter but is likely a lot of work. Again... I've seen another mid-build doing this. It looks like a lot of work with notching bars etc.

3) Re-use the diff and uprights but but create my own a-arms.

I'm going to try to tackle the back of the car before moving onto the front suspension more than I already have. I'm pretty much decided on using Mustang II 2" drop spindles. I've done some drawing (cracked out my old drawing board... none of this CAD stuff) and done some calcs and it seems they should work nicely. The added bonus of using the Mustang II suspension is that replacement parts will be easy to source and it doesn't look like their popularity is going to subside. For the front upper a-arms I'm going to buy rather than build. I'll likely still build the lower a-arms. There is going to be some expense with buying new for all the front suspension. One of the reasons I'm going to tackle the rear first.

Parting shot is one I couldn't help doing. It seems everyone takes it "out for a drive" when the frame starts to look like at least a little like a car. Julie was a good sport and took the pics.