Slow Car Fast
LIFE OF A GT
November 28, 2008 - Here's a shot of the only MGB - that I know of - to be fitted with Miata suspension.
The car was never completed, but it's very useful info. I've shown the rear subframe installation in the past, here's a shot of what was done up front. New frame arms. I'm going to do a little more reinforcing, especially of the upper shock mounts.
This picture also shows how much more potential space there is with the new setup. Combine that with a tubular front subframe like this one and all sort of room opens up.
entry 85 - tags: engine bay, subframe
November 30, 2008 - I wheeled the car outside and went nuts with the pressure washer.
The car's actually pretty clean considering it's 37 years old. None of the really thick oil-and-dirt goo I expect on something this age.
Once that was done, I brought the car back into its home for the next few months and put it up on jackstands. I was careful to get the car level, this will make it a lot easier to fabricate everything properly!
entry 86 - tags: dismantling
November 30, 2008 - The next step was to pull the front subframe.
Not a difficult task. It's astoundingly heavy. I forgot to weigh the car before taking it apart (whoops) but it's possible the V8-powered result could weigh less than the original.
I'm starting to reconsider the independent rear suspension. It would be cool to do, but it would be easier - and cheaper - to simply have the Camaro rear end cut down and reworked to run a 4x100 bolt pattern to accept Miata wheels. The solid rear isn't my first choice, but it's how the car was designed to run in the first place and there's a good body of knowledge on locating the rear axle already. Plus, it'll save a bunch of cash and I won't have to redesign the entire rear end of the car.
This car was never meant to be a lap record holder, but it'll end up on track at some point. Hmm. Decisions, decisions.
entry 87 - tags: dismantling, suspension
November 30, 2008 - The current engine bay.
I'll build up a brace to keep the front in line, then chop out those frame rails and inner fenders before building some new rails to fit the Miata subframe. My biggest worries are aligning the new parts and making sure I have sufficient strength, but looking at the factory stuff makes me wonder how much I need to be concerned about the latter. Still, it's going to see more stress than before. I should have an LS3 to measure for dimensions later this week, that'll help put me on the right track.
entry 88 - tags: dismantling
December 1, 2008 - I posted some questions about shortening the Camaro axle to the Grassroots Motorsports forum.
A good bit of information popped up: the Chevy S10 pickup used the same 7.5" rear end, but with a much narrower axle. In the case of the 2WD model, the axle is actually a little bit narrower than the Miata one. That's perfect! It gives me a little more room for wider tires and I'll have a cheap option.
I'll still have to adapt the axles for disc brakes (I can't bring myself to run drums) and convert them to a 4x100 bolt pattern. All possible. I have a good feeling about this, I think it'll be a good solution.
An extra bit of info from the LS1Tech forum - the 1998+ S10 use the same 28-spline axles as my Camaro, earlier trucks use a 26-spline. Very important to know.
entry 89 - tags: suspension
December 4, 2008 - Time to do a test-fit of the suspension.
In order to get it in approximately the right place, I'm going to set the lower control arm up so a line drawn between the inner and outer pivot points is horizontal. Most people try to set the arm horizontal, but it's the pivot points that matter. So step 1 is to figure out how high they should be off the ground.
I attached an upright to a wheel and measured the distance from the ground (approximately 8.5"), then figured out how high the car was jacked up (10" above normal ride height). So I want my pivot points 18.5" above the garage floor.
entry 90 - tags: suspension
December 4, 2008 - I can't lift the subframe quite as high as I'd like without cutting something, but here's an idea of the location.
Pretty good, actually. That rear mounting point should actually attach right to the bottom of the stock frame rail. The rails converge and rise in the engine bay, where I need them to spread wider apart. This is going to go fairly well, I think.
entry 91 - tags: suspension
December 4, 2008 - Of course, what I really wanted to know what how the wheel looked on the car.
Would my painted Miata wheels suit it? How far would it stick out of the fender well?
The answer is that it looks good. I like it. The tire diameter is 23" instead of the stock 24" on the MG, but I can probably live with that. I can run a 205/55-14 RA-1 (or some similar R-compound) to give me good traction without having to use a ridiculous tire size, and a 225/45-15 is a future possibility. The fact that I have a set of the RA-1s on these wheels in this size already is just icing on the cake.
entry 92 - tags: suspension, tires, wheels
December 4, 2008 - The tire does stick out a bit.
About as much as I'd expected based on my measurements, which is reassuring. A rough test fit shows that the Rabbit fender flare covers it almost perfectly. I'll pull one of the RA-1s off and test fit with that as well, but I have a good feeling about this - as long as I stick close to the stock +45 wheel offset, anyhow. I should probably make sure the +30 wheels with 205/50-15s fit, as that's what half of my race tires are.
The fairly radical camber is because I assembled this suspension out of spare parts and everything's just finger-tight. No attempt at alignment has been attempted!
entry 93 - tags: body, flares, wheels, tires, suspension
December 4, 2008 - Okay, I should stay away from that combination.
A +30 offset wheel with a 205/50-15 sticks out 3/4" further from the body. As the math says it should - there should be 20mm more when compared to a 195/60-14 on a +45 wheel. The flares don't quite cover them with room for wheel movement. That's okay, I can run a greater offset. We'll see exactly where the flares end up when they're welded in.
I pulled the rear axle off as well. There's a lot of room under there now!
entry 94 - tags: body, wheels, tires
December 6, 2008 - My secret weapon has arrived!
It's a plastic LS1 from P-Ayr that I picked up from Summit Racing. It weighs next to nothing, letting me pop it in and out of the engine bay easily instead of humping around 500 lbs of metal. All of the factory mounting points are represented by steel inserts, so I can also use this to work out my header setup as well as things like motor mounts. If I wanted, I could even install different heads. There's no plastic version of the T56 transmission yet unfortunately.
Most importantly, this lets me experiment with fitment without taking the Camaro apart quite yet.
It was expensive enough that I'm taking very good care of it, and I should be able to resell it after the build is over. Meanwhile, it's going to make life a lot easier.
entry 95 - tags: engine, replica
December 6, 2008 - The engine is in!
And there you have it, an LS1 in an MG. Wow, that was easy.
Okay, maybe getting the complete functioning engine with transmission and suspension might be a little more difficult. But still, the first test fit, fits.
I've got the engine positioned to put the shifter in the same place as stock. Actually, it'll end up maybe an inch further forward. This is the best I can do without actually cutting anything other than removing the motor mounts at this point. With the Miata subframe in place, I should have a decent amount of room for headers.
entry 96 - tags: engine, replica, test-fit
December 6, 2008 - The engine height was set to put the oil pan at or slightly lower than the frame rails.
This is a bit of a guess, but I think it'll work nicely. I might be able to sink it down another 3/4" or so.
With this positioning, the engine ends up in almost exactly the same position relative to the wheels as the Miatas we do at Flyin' Miata. Only the front pair of cylinders are ahead of the wheels and the height looks to be the same. This means I could use an off-the-shelf subframe. Wow, could it be that easy?
The threaded holes in the plastic engine mean I could simply bolt up the extra oil pan. I like this thing more and more...
entry 97 - tags: subframe, engine, replica, test-fit
December 6, 2008 - A test of the hood clearance will have to wait until I get an intake manifold.
There's one on the way right now. As with a number of the other parts, it'll probably get sold after the swap as I won't need it anymore. But placing a ruler across the edges of the hood opening looks promising. We'll see.
I might be able to push the engine back slightly, which would have a beneficial effect on the weight distribution. But again, given where it sits relative to the Miata and the extra weight of the coupe body in the rear - I think it will work pretty well here.
This picture also shows the huge amount of room I'm building in. There's about 3' of clearance all around the car with my work area up front. This is definitely a home project!
entry 98 - tags: engine, test-fit, replica
December 6, 2008 - These spare parts are left over from a Miata conversion.
They'll come in handy with my engine test fits, although I don't have a way to mount the crank pulley.
entry 99 - tags: replica
December 8, 2008 - The complete engine.
No, not mine. This is a 480 hp crate LS3 with a hot cam from GM Performance Parts. Yes, 480 hp. The Miata that's getting this is going to have more than 50% more power than our little MG. Yowza.
entry 100 - tags: engine
December 8, 2008 - Here's a new T56 to go with that LS3.
It's the same transmission as is in our Camaro donor, so I'll be using it for measurements.
entry 101 - tags: transmission
December 10, 2008 - The intake is here!
The ruler test shows that it doesn't really fit under the hood - but the hood isn't flat. Still, I'm hoping to get the engine a bit further down and back. I really need to borrow a transmission to try it for clearance. I think what I'll end up doing will be to strip the interior, cut out most of the tunnel and then rebuild to clear the trans.
entry 102 - tags: engine, fitment
December 10, 2008 - Before I spend too much time obsessing over the engine, I need to get the car's suspension in place.
That's a fixed location, unlike the engine which has a bit of leeway.
Basically, what I'm going to do is to hollow out the engine bay. The frame rails will come off, along with the inner fenders. That's not a big loss on the passenger's side, it was hammered very hard to clear that massive AC compressor years ago.
Once the bay is empty, I'll rebuild the frame rails with the right geometry to mount my Miata subframe. They're going to look quite different, but they'll attach up to the factory ones under the car if my tape measure is telling the truth.
Before any of this can start, however, I need to empty out the bay a bit more. So I'm pulling all the brake lines, clutch lines, wiring and miscellaneous parts. I've also reinstalled the radiator support to provide a bit more strength to the front of the car during surgery, and welded a couple of posts to it to prevent things from sagging.
entry 103 - tags: suspension, frame rails
December 10, 2008 - And here's what is going inside.
I walked into the shop at work and found this behemoth sitting on the floor. I have to say, it's very handy doing this swap at home while there are two LS3 Miatas being built at work as well as a completed LS1 Miata that's undergoing constant development. That's the drivetrain from the LS1 car, removed to get new heads and a cam.
It's a pretty close match to what I'm going to use. The subframe is the tubular version of a Miata subframe, with the same control arms and steering rack. It looks as if my engine positioning will be a bit further back than this one, which helps a bit for rack clearance, oil pan clearance and weight distribution.
It sure makes the transmission look huge!
entry 104 - tags: engine, subframe, transmission, fitment