build diary

May 6, 2004:
Lots of differential design going on!
This is fun stuff. Lester Seal reports that he built an E Production Miata that didn't have a PPF. His solution was to run a short piece of tube forward from the top of the diff and anchor that. It was triangulated with a tube coming up from the bottom of the diff. This reportedly worked quite well, and an upside-down version could certainly be adapted to the Seven. It's also something that could be retrofitted so I'm going to try simply putting in a hard mount in place of the rubber bushings I have at the moment. Combined with a proper locking nut that should prevent any movement. It's also very light (I have some aluminum spacers to replace the rubber) and easy. I figure I'd rather put the existing mount into compression than try to hook something up to the bottom of the frame and have it in tension.

This is interesting. They're basically intended to bypass the bushings in the diff mounting arms to give a more solid mount. A shiny version of my Shoe Goo and the plastic inserts I'm using now. I can't see how it benefits a Miata but I was actually considering exactly the same thing for the Seven yesterday before these were brought to my attention!

I've also been looking at the driveshaft angle. I've got the nose of the diff too high at the moment - it really should be parallel with the output shaft. It's a good thing I was looking at the diff and caught that.
entry 277

May 7, 2004:
I didn't have a chance to do any measuring of driveline angles last night.
However, I did order my brake and clutch pedals and hydraulics as I figured it would be easiest to run the lines before the engine goes in. I'm pretty excited about this!
entry 278

May 10, 2004:
Lots of work this weekend.
First, driveline angles. I suspect all of CMC's engineering has been done with the smaller 1.6 diff, but even then a mounting point that is about 1" higher would make a big difference. The bottom of the bigger 1.8 differential hits the frame before the diff gets level, and the longer nose of the 1.8 also means the driveshaft is shorter. Thus the driveline angles in my car are now are as good as they can be but still not ideal. The driveshaft angle is a touch under 4 degrees and the diff and transmission output shaft are about 3 degrees out of alignment. I'll see how this works - if there are vibration problems I'll remount the diff higher up in the frame.

I've talked to a couple of engineers about the rear diff mounting as well. They are unanimous in condemming the existing mount for the nose of the diff. I'll have to make a stumpy version of a PPF to fit inside the frame. This could be a bit of a challenge, but it should be worth it in the long run. Lester Seal has the correct idea with his plan to use the PPF.

In other news, I've cut out the bottom of the dash for more legroom. The dash is looking good although my first attempt at some glass to cover the gauges was pretty hideous. I also riveted the rear bulkhead body panel into place - I've been looking forward to doing that for some time! It's the best fitting body panel so far. It needs one small bend at the bottom and two notches needed to be cut out of it, but all the angles appear to be square and it looks good in place.
entry 279

There's a limit to how low I can drop the big 1.8 diff.
You're looking at the bottom of the diff meeting the frame. I'd shaved this down a little since the photo was taken but there's only so much meat that can be removed.
entry 280
In order to level out the differential as much as possible, I shaved down the steel inserts inside the diff bushings.
It helped.
entry 281
A great way to measure the output angle of the transmission.
entry 282
The dash has been reshaped for leg clearance.
entry 283
I'll call this panel the rear bulkhead for lack of a better name.
It's the best fitting panel of the lot so far. I needed to cut two notches to allow access to the front bolts for the lower control arms, otherwise adjusting the alignment would be difficult.
entry 284

May 11, 2004:
I started installing the rear sheetmetal last night.
The passenger's side went in pretty easily, but I hit some snags with the driver's side. More information to follow...
entry 285

Beginning to install the rear sheetmetal.
entry 286

May 14, 2004:
The problem with the rear body panel was alignment on the driver's side.
I had an inkling this might be a problem, but I thought it was due to a badly cut panel. That wasn't it - the round tube that forms the upper portion of this body is welded on crooked. You can get a hint of it in photo 87 - the driver's side is higher than the passenger's. It's not bent as there's a consistent angle from one side to the other. I'll either have to make a matching, crooked rear panel or cut those parts up and reweld it. This has prompted me to measure a few other dimensions on the frame, as you might expect. I got a bit of a scare when the wheelbase came out 1" longer on one side than the other but this was tracked down to a rod end that wasn't installed quite as far as the others. A few other measurements are showing up 1/4" out here and there, but nothing crucial as yet.

My brake and clutch pedals have also arrived! This was a fun day of unpacking white Wilwood boxes. I'm going to have to modify the frame in order to fit these. Time to wire the garage for 220v, then. I'm using twin master cylinders for the brakes with a balance bar. I've also got an adjuster so that the bias can be tweaked from the cockpit. I'd rather not have to get inside the driver's footwell to adjust the bias once everything is installed!
entry 287

Uh-oh.
That's not how things are supposed to line up. Look at the cutout for the shock mount as well as the bottom tube.
entry 288
Brake pedal and masters!
entry 289
Clutch pedal and master!
entry 290
The brake pedal in place.
It'll take some modification to get this mounted.
entry 291
Playing with switch layout.
That's the ignition switch and starter button. The blue knob is the brake bias adjuster and it's going to go over by the handbrake lever. I figure that if I'm adjusting the bias while driving, I won't want to accidentally turn off the ignition...
entry 292

May 17, 2004:
A fun weekend of playing with brakes.
The frame surgery has been done and it worked out quite nicely. In the next few days I'll put together a reinforcing plate to replace the parts I had to cut out. It should be a nice clean setup when I'm done. Now that I have the pedals in place I can start finalising the rest of the driving position. Happily, there's even enough room in the footwell for me to wear normal shoes. I'm not sure if I'll be able to work out a dead pedal of any sort. I also have to find a couple of pipe to flare adaptors - for some reason, the Wilwood master cylinders have pipe fittings on them. That seems a little odd but there may be a good reason. I'm used to dealing with flare fittings for the brakes.

A bit of a puzzle. CMC put a small bracket on the frame that's intended to be the junction between the clutch flex line and the hard line. It's placed in a similar location to the Miata one - but the Miata has it quite a bit higher. I realised that the factory bracket could be bolted on the firewall on the other side of the engine, giving a nice clean install that still leaves enough room for significant engine movement. This makes the hard lines easier to route and tidies up the engine bay. I'm pretty happy with it.
entry 293

In order to fit the pedals, the frame needed a little surgery.
entry 294
The pedals in place!
entry 295
The final location of the gas pedal will be finalized when the brake system is plumbed.
entry 296
To reinforce the frame where it's been cut away, I'll be welding a plate into place.
Here I'm working out the dimensions.
entry 297
The master cylinders.
Those brake masters have bigger reservoirs than is necessary, but I'd rather have too much fluid than too little! It was also a matter of bore sizing and availability.
entry 298
There's not much clearance between the clutch master cylinder and the frame - but there's enough.
entry 299
The balance bar for the brakes can be adjusted remotely.
You can see the cable running through the transmission cover.
entry 300
In order to use my residual pressure valve (required because of the low mounting of the masters), I'm going to have to be a little more creative with the plumbing.
The motor mount is in the way!
entry 301
The clutch hydraulics.
For some reason, CMC put a bracket for the clutch flex line on the passenger's side of the transmission tunnel. I'm not sure why. This is close to the Miata location, but it's much higher on the Miata. To use this on the Seven would mean the clutch line would be fairly convoluted. I found that bolting the factory bracket to the firewall on the driver's side made the installation much cleaner and simpler.
entry 302
The clutch system is done.
This line is very three-dimensional and the bends make a lot more sense when you see it in person!
entry 303
<< | show individual entries | >>