Targa Miata
March 7, 2007 - We were originally going to run a clutch from a Mazdaspeed MX-5 turbo car.
It's a great setup, with a smooth take-up and a light pedal. But our clutch got sold to a Flyin' Miata customer.
This particular clutch is a prototype unit of a model that will be available from Flyin' Miata in about six months. I had a chance to test its twin in a car earlier this week and it's a beauty. It will have no difficulty handling the power we need, but more importantly it's a real sweetheart to drive with a light pedal. Excellent.
entry 89 - tags: interchange, drivetrain
April 2, 2007 - Time to pop the diff in.
The stub axles are lubricated with a bit of grease to make sure they'll slide in nicely (which they did). Funny, that green grease is showing up all over the place now.
entry 113 - tags: drivetrain
April 6, 2007 - The halfshafts are in.
These particular ones have me a little concerned - they're from a very high mileage car. I may have to change them later. They'll be well tested before the race.
Another problem has appeared with the parking brake - one caliper appears to be misbehaving. I'll have to pull it off and see if something is seized. The history of the calipers is also a bit of an unknown. At least it's not difficult to find a replacement.
entry 115 - tags: drivetrain, brakes
May 3, 2007 - The transmission is in!
That's one step closer to firing up the beast. I've become used to installing transmissions on the lift with a nice transmission jack. I guess it was time to pay my dues, working alone under a car on jackstands. With a bit of muscle, a helpfully placed strap and a floor jack I managed to get it in without too much drama. Now all I need to do is find all of the various bolts to hold it in place.
I'm a little disappointed in myself. After I installed it, I figured it would have been fun to paint the power plant frame some bright and obvious color like red to draw attention to it. Why not? But I didn't. Maybe I'll pull it out tomorrow and give it a quick spray paint job...
entry 160 - tags: drivetrain
May 6, 2007 - I couldn't resist.
I had a spare power plant frame, so I blasted it clean with the pressure washer and gave it a coat of nice red paint. For those who follow my various builds, it's the same paint I used on the interior of Basil. But there's a functional reason to change to the other PPF as well. Note the little "tooth" at one end of the painted PPF. That's to protect the bolt heads at the differential. Not a bad thing to have on a car that could easily bottom out! So there is a method to my madness, although the red PPF does make me giggle every time I see it under the car.
entry 161 - tags: drivetrain, other cars
May 6, 2007 - The subframe brace here is from a 2003 model.
Not only does it stiffen up the rear suspension, but it also protects the differential. It doesn't protect against rocks as well as a legit skid plate would, but I'm more concerned about bottoming out the car on pavement and it should help out there. It also wouldn't be difficult to add a plate or two to this solid frame.
The little skid plate on the red PPF is visible here as well, and the brace does make it rather obsolete when I look at it now. Oh well.
It's also possible to see in this picture that the exhaust system is in place. The main power line running from the battery to the engine bay has been cut and modified so it goes through the cut-off switch, then the wiring was properly secured. The driveshaft is on - and all of a sudden, I have a complete drivetrain!
entry 162 - tags: exhaust, wiring, drivetrain, interchange
June 13, 2007 - Time to fill up the transmission and differential with some good fluid.
It was a quick and easy job - until I was cleaning up and I noticed an empty MT-90 bottle by the back of the car, and an MT-90 and 75-90 bottle by the middle. Whoops!
So, do I drain out the fluid and replace it all? Or do I figure that I'm probably in good shape? Or do I run this for a few miles and use it to flush out the diff and transmission? The latter could probably use it, honestly. I checked into the history of this particular unit and it turns out it spent a fair bit of time bolted to a 250+ hp car. Let's just say it's not the transmission that will be used in the race!
All I know is that I don't feel like making the change tonight.
entry 208 - tags: drivetrain
August 12, 2007 - A number of little things were done today in order to prep the car for the track day on Friday.
This little filter is on the valve cover to feed the PCV system. That's a pretty misunderstood system, and in most cases a filter on the cover would be a bad idea. In my case, I have an engine management system that uses manifold vacuum to determine load, so there's no problem if some air comes through the valve cover first.
The car also got the first oil change and is now running full synthetic. The transmission and diff were drained and refilled with the correct fluids this time (whoops), and judging by the condition of the stuff coming out of the diff it's not a bad thing that I "flushed" it. I spent a bit of time working on exhaust system alignment, I'm afraid I'll have a bit of a rattle on hard cornering.
On the less mechanical side of things, I put some small rubber bumpers under the trunklid to ensure it doesn't rattle at all. Windshield wipers are in place (and functioning) and I added Grassroots Motorsports and SSR decals to the side of the car in front of the door. This is partly to acknowledge the support from GRM (go pick up a copy of the October 2007 Grassroots, you'll find my Seven in there) and to give SSR a bit of credit for originally supplying the wheels being used on the car. It's also partly a test of how to arrange sponsor decals on the car. Oh, and there's a big black FLYIN' MIATA on the nose of the car now to match the rear bumper. Pictures will come.
entry 289 - tags: drivetrain, exhaust, decals
September 29, 2007 - The sways are installed.
There's a 7/8" bar on the softest setting up front and a 5/8" bar on the softest setting in the rear. I considered using the 14mm Mazdaspeed bar in the rear, but the aftermarket version has longer arms so I suspect they're about the same in the current setting - and this gives me more options. This current setup is slightly more biased towards front stiffness than I usually run. Typically I'd have that rear bar on the middle setting. I also have a factory 12mm rear that I can throw on if required. One nice thing about the Targa Miata is that I can install the rear sway bar without even jacking up the car, thanks to the cutaway rear bumper!
I headed out for a run to test the bars. To make things more exciting, the wind was howling and rain was splattering down. It's the best imitation I've seen of Newfoundland weather here in the Colorado desert. I'm assuming I won't have to dodge tumbleweeds in the rain in Newfoundland, though.
The car feels great. It's got a very nimble feel and it just glides over imperfections in the road over 20 mph. Below that speed there's more impact felt through the body but the car just deals with it. One 2nd gear corner with a very corrugated exit caused the rear end to lose traction, but it had more to do with the cool tires, wet road and too much power than with the damaged pavement. The Torsen diff let the loose wheel just spin up, an indication of how little traction there was. It was a smooth breakaway and I just rode it out. The car is very eager to turn in and feels a bit darty, but that could also be the strong cross winds. I'll see how it feels over the next few days. The next track session is scheduled for November 3rd, but I might be autocrossing the car next week. We'll see.
entry 320 - tags: suspension, drivetrain, testing
October 14, 2007 - Autocross baptism.
I've heard the Targa described as a combination of an autocross and Solo I racing. So I'm using both types of venue to test. This autocross was put on by the local Corvette club. They allow a small number of "metal" cars to participate by invitation, and I'm usually welcome. So I brought out both the Miata and the Seven.
So how did the car do? Quite well, really. I learned that it's quite easy to drive on the autocross course, with great braking ability and a nimble feel - just what you'd hope for out of a light Miata. The car's easy to drive although I'd like a little more feedback on a locked wheel.
What I didn't expect was the inability to put down any power. Again. It's not a wheel lifting this time, but it sure does act like it. I'm wondering if the Torsen LSD is actually a Torsen. Maybe I got my hands on an open diff instead. I never actually checked inside the casing. I have a good differential in the Seven that would work well in this application, but I hate to take it out.
On my third run, I almost entered a trance and just drove around the course. No real effort was involved, the car just did what it was supposed to. The end result? A time that was 0.3 seconds slower than a rotary-powered Fiat X1-9 autocross special and a C5 Z06 Corvette - good enough for fourth fastest of the day out of a field of about 24 cars. First place was, of course, the Seven.
So, in all a very good day. The car performed well despite a real weak point and showed no evil handling characteristics. That's about all I could ask at this point!
Video now available!
entry 324 - tags: testing, other cars, drivetrain
October 17, 2007 - Bad news.
I'm not sure how this happened, but it's my fault. Way back when I obtained the differential out of a wrecked 2003, I assumed it was a Torsen limited slip. I'm not sure why exactly, but I jumped on this particular unit because it had the 4.3 rear end ratio I wanted. Well, now I know why I've been having so much trouble with wheelspin.
It's not a Torsen.
The car was a base model. I might have been fooled by the big brakes on it, something that was exclusive to the Torsen-equipped suspension upgrade until 2003 when it became standard. But I've been trying to maximize rear traction with an open diff! Argh. Of course, Flyin' Miata doesn't have any Torsens of any sort in hand right now, so if I want an LSD for the Nov 3rd track day I'm going to have to pull the Guru diff out of my Seven. This is a great diff and one I'd love to run, but I hate to handicap the little car to get it. I could run the track day with the open diff and wait for a Torsen to become available, or I could source a diff elsewhere. Decisions, decisions...
entry 327 - tags: drivetrain
October 30, 2007 - Time to get ready for a big test.
There's a track day in Pueblo on Friday. This will be the first time I've taken the car on a "big" track, instead of the tight kart track I've been using. It's going to be interesting to see how it does.
One of the jobs to be done before heading to the track 200 miles away is to swap out of the differential. Howard Booster is building a Westfield, and graciously allowed me to borrow his differential for the weekend so I could test with a Torsen and not have to disassemble the Seven. Thanks Howard!
While pulling the diff, I discovered the source of a banging noise under hard cornering. I'd figured it was the exhaust hitting the differential. Close,but not quite. It was the exhaust hitting the flange on the two-piece halfshafts! You can see the evidence in the picture. The two piece halfshaft was never used from the factory with the 1999-05 exhaust system I'm running. I'd used two piece units because it makes it a bit easier to pull the differential, but after dropping the open diff out of the car today I've realized that it doesn't really make all that much difference! Substituting one-piece halfshafts gave me the clearance I need.
So, almost ready to go. I'm going to tow the car over so Janel can come with me. I'll pile a bunch of swaybars in the back of the tow vehicle so I can play with handling, and I'm going to try a couple of different alignment setups. Oh yes, and I have to receive and install the new suspension! Little stuff, you know.
entry 330 - tags: exhaust, drivetrain, interchange
June 8, 2008 - One of the things on my "to do" list after the TSD was to swap out the differential.
This will actually accomplish a number of things. It will let me see if a different differential still has the traction problem on right turns. The previous diff was from a 1999 Miata. The current one is a Type 1 Torsen, which acts a little bit differently and can handle a wider split of available traction.
It will also raise my gearing a bit. Right now, it's a bit on the short side. I had originally figured I'd run the 4.30 because it gave me a 120 mph engine speed of 6120 rpm. 120 mph is the maximum speed allowed in the Targa. But the gearing's just too short, and I'm always looking for another one. So I'm going to try a 4.10. 120 mph speed drops to 5835 rpm and I can reach 42 mph in first if I have to. You can play with Miata gearing on the Flyin' Miata website - the default setting just happens to be my new setup.
I'm also testing out some new polyurethane differential mounts. It will make my shifts a bit more precise. It's not that hard to do a 2-5 shift, and it'll really slow you down. This will help. Besides, it's a new product for Flyin' Miata so I had to give it a shot.
entry 469 - tags: drivetrain
June 10, 2008 - Testing results.
The influx of hot air seems to have succumbed to my patching and the car no longer smells like exhaust fumes. So that's good.
The car is much happier with the 4.10 rear end. I've always liked this gearing combination. The stiffer mounts in the differential have cut down on shifter movement and the car shifts very nicely now. So that's an improvement. There should theoretically be an increase in NVH from the new mounts but it's rather hard to tell in this car!
I took the car out to the track again for a few laps, just to see if the rear end was hooking up any differently. And the answer is nope. Maybe a little bit better, but I can still spin up that right inside wheel if I am being aggressive. It takes a turn that's tighter than any that would be used on the street - aka, that would be found in the Targa - but I'm starting to obsess about this a little bit again. On the theory that the car is rolling too much and the rear sway bar just can't deal with this much articulation, I stiffened up the low-speed compression. While the car get a bit happier in transitions (I need to spend more time with this adjustment, as I should be able to really make it pivot nicely) it didn't make a significant difference.
I do really have to thank the guys at the Grand Junction Motor Speedway for working with me and letting me drop in once in a while. When I left today, they were surprised that I'd only taken a half dozen laps!
I'm probably going to swap all the control arms out. The bushings seem to need lubrication again. That's odd, because I've run these sorts of bushings for years in the past without any noise. But that dirt road really seems to have done a number on them and they sound terrible. So the arms have to come out at least partially, so why not experiment? I will check to make sure it's not dry sway bar bushings, which I don't think were very well lubricated on installation. Remember, I installed them at the track and didn't spend a lot of time greasing. Hmm.
edit - I did check, and it is the ungreased front sway bar bushings. Duh. The control arms are fine.
One reason to swap out the arms is because I've managed to accumulate a set of 1999-05 control arms. The rears have only 1700 miles on them so they have nice fresh bushings, while the fronts are higher mileage. The later arms are more heavily reinforced for more strength.
Third, I'm also hoping it'll let me get a little more camber up front, which will allow me to run a smaller (or no) rear bar, which will help with the rear traction.
First, I'll check the cornerweights to see if the right rear is out of whack. The traction problem is not as bad with a passenger, and of course I'll have a passenger during the race! I can tell when I'm going to have problems with the traction, as it's all due to the weight on the right rear wheel. Actually, it's the weight on the right rear and the antics I get up to in order to provoke it.
entry 471 - tags: testing, drivetrain, ergonomics
May 16, 2011 - Try to guess which clutch is from a four-cylinder Miata and which one is used for a healthy V8.
Try to guess which clutch is from a four-cylinder Miata and which one is used for a healthy V8.
entry 822 - tags: drivetrain
May 17, 2011 - I found a culprit!
I've been having trouble getting the T56 to sit properly - it hasn't been fully bolted in to place yet. Well, it turns out that the pilot bearing was a special one for the T5, which is too thick (and too large a diameter) for the T56 input shaft. Frustrating, but easy enough to fix once Bill helped me find the problem. Once that's replaced, the engine and transmission can go in - and stay there!
entry 830 - tags: drivetrain
May 20, 2011 - Finally, the drivetrain is all buttoned up and ready to install.
I installed the headers as well as some of the power steering plumbing while I had easy access.
entry 831 - tags: Drivetrain, v8
May 20, 2011 - Much better - the engine and transmission snuggled into place.
The V8Roadster rails are laser cut, so the bolt holes were in the exact same location as the studs I'd welded into place earlier. That saved me a lot of drilling! The transmission crossmember location ended up a bit off because I'd aligned the rails for the T5 setup, but that was easy enough to cope with.
entry 832 - tags: Drivetrain, v8