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Squarefour's Miata Based +442
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Author:  squarefour [ October 27, 2018, 8:39 pm ]
Post subject:  Re: Squarefour's Miata Based +442

Front Big Brake update:

I ended up using 05-14 Mustang (rear) rotors (11.8" OD) and the stock '90 Miata calipers. I had to drill the rotors for 4x100 and reduced the braking area width to match Miata pad size. The Miata caliper brackets had to be clearanced a bit for the bigger diameter. The caliper adapter brackets were super simple to make -the 1/2 aluminum thickness was perfect as-is!
Total cost of this mod was less than $100, including new brake lines.

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Author:  squarefour [ October 27, 2018, 10:28 pm ]
Post subject:  Re: Squarefour's Miata Based +442

K motor update:
Installed very expensive oil pan that I naturally had to spend hours grinding on to get to fit. (I guess DC5 oil pump is a little bigger?)

Spent pretty much an entire weekend making the silly FPR bracket.

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Author:  squarefour [ January 7, 2019, 3:01 pm ]
Post subject:  Re: Squarefour's Miata Based +442

So the 2000 Miata 3rd member triggered a giant domino-effect clusterf--k. I am just now seeing the light at the end of that tunnel.
Unbeknownst to me, I have a 1983 RX-7 rear-end housing, not the 84-85 I wanted. Thanks, junkyard!
Two differences:
-bigger bearings
-26 splines from 24

I learned this when my axle shafts clunked around inside the newly-installed Miata 3rd (26 spline).
OK, I thought, I will get custom axle shafts with small bearing size/26 spline. Moser Axle says "can't do it", after a month of miscommunication.
My next idea was to get 84 housing ends, machine/weld some adapter parts and weld into the ends of the 83 housing. This will increase track 5", not a big deal as I was using big wheel spacers to use FWD wheels.

I got 84 ends from an RX-7 guy in Tennessee, and ordered 2.5" longer 84 rx7 axle shafts, 4x100 pattern, from Moser. I made little adapter pieces from 1/2" wall DOM, pressed them into the housing ends, had a buddy TIG them, then machined some more.

I got the shafts from Moser.
Two problems:
-No 4x100 pattern, just a weird 4x127.
-There was only about 1/2" of spline interface into differential. This is probably not be a problem with the Moser axles, and may be the case anytime a Miata 3rd is used in an RX7 housing.

I decided getting another set from Moser would take too long, so I machined these to work. I made a drill guide on the mill, and modified my drill press to accept axle shafts (big hole in the table).

I machined 7mm off the bearing stop to get 7mm more spline interface, and will use 7mm spacers between the axle flange and the brake rotor to compensate.

I then hammered the adapter pieces into the 83 bearing races. I machined an aluminum puck to press on an axle shaft so I could use it as an alignment fixture while welding. I also used bolts thru both brake tabs.
I then welded away, stitching to avoid heat/warpage.

Now I just have to finish my brake brackets, a little paint, and I may be on the road again.

PS1: Yes, I probably should have just given up and went back to the 3.90 3rd, but the 83 axles would have been a weak point with the new motor.
PS2: Yes, I probably should have just started over with a fresh 84 housing, but there is a LOT of custom bracketry on there...

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Author:  squarefour [ January 13, 2019, 6:08 pm ]
Post subject:  Re: Squarefour's Miata Based +442

Almost done -finished the brake brackets and the "hubcentric spacers". Had to do a little more machining on the rotors and then paint them.
You can also see the new 2.5" monotube coilovers.
The first picture is just to prove I sanded and painted the boat anchor before putting it in. (Also, chopped off the useless bracketry.)

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Author:  squarefour [ January 14, 2019, 4:31 pm ]
Post subject:  Re: Squarefour's Miata Based +442

RideTech 24139901 coilovers, BTW, chosen because of very short 9.4" compressed hgt (same as previous QA1s). I have lost an inch of travel over the QA1s, however.

Author:  squarefour [ January 14, 2019, 4:56 pm ]
Post subject:  Re: Squarefour's Miata Based +442

The rotors, which I forgot to take a pic of, are modified Raybestos 980221R, Mercedes E320 03-09, among others. 11.8" OD x .394" thk. I just had to drill the 4x100 pattern, and I machined down the contact strips to match the RX7 pads.

Author:  squarefour [ March 11, 2019, 3:30 pm ]
Post subject:  Re: Squarefour's Miata Based +442

Back at work on the K motor. Cleaned up and simplified the wiring harness, plus a giant cut and shut operation to the valve cover, which saves a whopping 3/8" of height. Engine will now fit (barely) under hood. I may trim a little off the trans/motor mounts for insurance.

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Author:  squarefour [ March 12, 2019, 10:28 am ]
Post subject:  Re: Squarefour's Miata Based +442

welded up-

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Author:  FastG [ March 12, 2019, 2:26 pm ]
Post subject:  Re: Squarefour's Miata Based +442

I did a K24 swap, i don't know if you checked out my posts. some i did the same as you some i later changed. I used a very small alternator and was able to keep it in the stock location and still get the steering arm thru, checkup

download/file.php?id=42992&mode=view

I used the same style front facing throttle body, as soon as I opened the hood at the dyno shop, the first words out of the dyno operators mouth was " why have you used a front mounted throttle body, you inlet system sucks". So last year I swapped to a rear facing setup, it's a lot better and soon there will be a nice cold air airbox setup.

viewtopic.php?f=4&t=19374

General K24 swap

viewtopic.php?f=4&t=16975

Love the Honda motor, I am really glad I made the change.

Graham

Author:  FastG [ March 13, 2019, 11:22 am ]
Post subject:  Re: Squarefour's Miata Based +442

Just a couple of other things I found

1. I also used a Canton sump, I had real problems getting it oil tight, the original is cast with a perfect machined face, were the Canton is a stamped steal flange that has been welded to, so it's not perfectly flat. I had a couple of goes sealing it without perfect success. I found Rock Auto list a gasket, the stock does not use a gasket. The gasket sealed it up perfectly.

2. I was plagued with a slight oil leak from the front timing cover that I had real problem tracking down. On the K24 there is a provision for an engine mount on the front cover that I obviously did not use, but it turns out one is a thru bolt, it's not in a high oil area so the leak was slight and tough to track down. A short bolt and some thread sealer solved the leak.

Hope this info helps

Graham

Author:  squarefour [ March 13, 2019, 1:43 pm ]
Post subject:  Re: Squarefour's Miata Based +442

>>I also used a Canton sump, I had real problems getting it oil tight.

I used a gasket, because of these reports. The flange seemed flat, but I had to clearance the baffles a LOT to clear the oil pump. Perhaps because it's a DC5 pump?

>>A short bolt and some thread sealer solved the leak.

Well that's alarming. I am using those holes to mount my alternator. I will pull the bolts and put on some sealer.

>>I did a K24 swap, i don't know if you checked out my posts

I studied them very intently:)

>>I used a very small alternator and was able to keep it in the stock location and still get the steering arm thru, checkup

I did not have room for even the tiny alternator in the stock location, with my steering setup.

>>I used the same style front facing throttle body, as soon as I opened the hood at the dyno shop, the first words out of the dyno operators mouth was " why have you used a front mounted throttle body, you inlet system sucks". So last year I swapped to a rear facing setup, it's a lot better and soon there will be a nice cold air airbox setup.

There is no way I could do rear feed without modifying the chassis. I am not sure why front feed would drop power, maybe because it picks up hot radiator air? I will rig up some kind of airbox that pulls from the nosecone.
A few Miata guys have posted decent hp #s with front feeds, BTW.

Thanks for the input!

Author:  FastG [ March 13, 2019, 2:44 pm ]
Post subject:  Re: Squarefour's Miata Based +442

I guess the K series motors like a long smooth inlet tract, The dyno guy just pulled out a longer inlet pipe screwed it in and we got an extra 8bhp, plus your picking up air that has already been thru the radiator. So in you can build some sort of cold air setup. Its very tough to use a rear throttle body setup on a Miata because the head is very close to the firewall, with a front mount you can easily get outside of the radiator to get nice cold air.

Graham

Author:  Miatav8,MstrASE,A&P,F [ March 13, 2019, 4:01 pm ]
Post subject:  Re: Squarefour's Miata Based +442

I've been meaning to say for some time now how much I like the groovy paint job. :cheers:

Author:  squarefour [ March 13, 2019, 6:23 pm ]
Post subject:  Re: Squarefour's Miata Based +442

>>The dyno guy just pulled out a longer inlet pipe screwed it in and we got an extra 8bhp

OK, that makes sense. How long are we talking? I don't think I can manage more than a couple feet to the airbox, and then another foot to the air inlet next to the radiator.
I probably shouldn't sweat 8hp. I mean, I have a hundred now...:)


>> I like the groovy paint job.

Thanks! I'm definitely not tired of it yet (like was predicted by some friends).

Author:  davew [ March 14, 2019, 7:44 am ]
Post subject:  Re: Squarefour's Miata Based +442

Duck the inlet air flow to the cold air box over the top of the radiator.
Then seal the cold box up against the top of the nose cone, preventing entry of the hot air from behind the rad. davew

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