Made up a Covid19 list of “maintenance” items that needed addressing. I have been “living” with most of these issues for years.

1. Improve throttle response (reprogram AT45 microprocessor in Throttle body circuit to eliminate MS delay on “throttle on”)
2. Stop supercharger moan when lifting throttle at high boost levels (higher flow control valves feeding SC bypass valve, and 2 of them)
3. Fix the boost pushing the wastegate open issue. (used a bleeder valve, to provide a lower boost source pushing on the wastegate)
4. Oil consumption -turbo is leaking oil into the intake again (biggest problem was a leaky PVC valve, but I ended up putting in a catch can -I should have read the catch can thread first though)
5. Need SC bypass to always work. (need vacuum storage -used a soup can)
6. To improve high end power, bypass the supercharger. (First program current SC bypass valve to open, when Turbo is bypassed. Then add an additional dump valve, using an electric solenoid)
7. Fix pipe from turbo to intercooler, which doesn’t fit properly (remake pipe with BOV on it)
8. Fix battery grounds. (this has been causing odd MS readings for a couple of years, but has really been just a nuisance)



Some Pictures:

rebuilt pipe from Turbo to Intercooler, and shorter more direct line from valve cover to intake pipe. Bleeder is also mounted to intake pipe. This bleeds off about 10psi that is being applied to the wastegate.
https://cimg0.ibsrv.net/gimg/www.mia...f537c3d310.jpg

Biggest bang for the buck was replacing the mac valve with 2 mitsubishi (Miata) valves. This improved throttle response, and reduced supercharger moan when letting off throttle.
Yes, the EGR is a bit weird but should work ok.
https://cimg9.ibsrv.net/gimg/www.mia...3523743797.jpg

This additional bypass valve looks a little wonky yes. The original valve had a vacuum actuator on it, which failed after about 5 seconds. This one is electric, so should be good
for a while (assuming it doesn't vibrate off) In the picture, it looks closer to the alternator pulley, than it really is.
https://cimg6.ibsrv.net/gimg/www.mia...95543eeec4.jpg

And I finished the clutch parts.
I didn't mention it, but I did buy an additional clutch/pully/electromagnet made by Ogura. This is a Japanese company which specializes in various types of clutches.
At first glance, the Ogura parts looked identical to the "no name" clutch I had, but close inspection revealed that the "no name" clutch had a number of changes which were not logical at all.
Anyway, I used the Ogura clutch as a guide and ended up with a clutch with 12 square inches of friction material, along with the standard 6 square inches of steel "friction" material.
I don't want to take the car out of service right now to test, but I will over the summer some time.

New clutch parts on top (pulley, clutch and centering ring). Old clutch parts on bottom. Bigger=better (I hope).
https://cimg3.ibsrv.net/gimg/www.mia...f1c8309996.jpg
I put pins in the hub, to keep the main shaft true. Hopefully this works for long enough to test this out. I also got a new DC-DC upconverter. The previous unit blew up again, so I got one that is rated at 1200w!
Maybe it will handle the 100w I am asking of it.
https://cimg1.ibsrv.net/gimg/www.mia...788c7fb182.jpg

By stopping the wastegate from prematurely opening, I am seeing the transition to turbo fully spooled about 500rpm sooner (4500rpm on 5th gear pull).
Also, by bypassing the supercharger (1 of the 2 bypasses active currently), I am seeing a bit more torque once the turbo gets going (also running a bit more boost).
Unfortunately I am having some traction issues, and have been unable to log high rpm HP. I contemplated putting on the drag tires, but think that will wait until I make another trip to the drags.

that's it for now.

Nice work man. The little things on these complicated systems really eat me up too. After the upgrades this last winter it appears as if I am on the backside of things in terms of getting stuff addressed. Looks to me like you are probably getting there too. Keep it up!

Great build mate many cats given! I haven't got all the way through yet but I'm saving this one to keep me entertained.

Absolute dictionary definition of built not bought, with all the highs and lows that entails. Massive props.

^ Hey, thanks man!

You are doing some cool stuff, which is reminding me that I have a few things I want to do this winter, but have not been motivated. (other things on the go)
Maybe as things warm up a bit.

So even though I am working very very slowly on the clutch and cool shirt project, I decided it was time to buy some more parts.

I got new turbo, fuel pump, 3.63 diff gears, 4 bar map sensor and rims/tires. May go for new injectors, but will see what the pump does.
https://cimg6.ibsrv.net/gimg/www.mia...fa6586560a.jpg

My current turbo is a TO4E 50 trim, which means that the turbine and compressor exducer sizes are ~9mm smaller on this GTX2867.
For some events, I get bumped up in class because of both SC and Turbo. So I disconnect the SC belt to get to a turbo only state.
The throttle response of the T04E by itself is not great so I didn't have too much success when I do this.
For example when turbo only, if I floor it and hold it at 4700rpm with the brakes, the TO4E takes 1.6 seconds to spool up to 22psi.
A lot can happen in that time.
So this new turbo will spool faster and support higher HP than the old turbo. For now, I will use the same crappy exhaust manifold.

I know most are going the Kraken/BW route, but this combo pushes the turbo pretty far forward in the engine bay which would give me some significant challenges routing the intake lines.
(I am not sure it would be possible) Maybe down the road a Kraken low mount might be made to fit.

I am very interested to see how this new turbo responds throttle response wise, both when on it's own, and when paired with the SC.

Wow! Quite a haul man!

225/245/15's RT660's on 9" rims compared to 205/50/15 RE71R's on 8" rims.
https://cimg6.ibsrv.net/gimg/www.mia...3dcca85910.jpg

At one point I lowered my radiator, so needed a longer than stock hose. I ended up splicing 2 miata hoses together, which was leaking badly last fall.
I discovered Dayco have a dimensional lookup tool so you can easily find if there is an available standard hose to fit your custom application
Dayco dimensional lookup
Old hose on the left.
https://cimg0.ibsrv.net/gimg/www.mia...df2f8d95ea.jpg
Yes, I have a bit of an oil leak too.

So I purchased a Fugi Diff, in order to get a 3.63 gear set. The purchase price was based on the Fugi limited slip being bad, but I reasoned that since not too many people
were complaining that they were failing, it was possible that it might be good.
https://cimg5.ibsrv.net/gimg/www.mia...ffed5bd1d1.jpg
After seeing what the part looks like in person, I have changed my reasoning. Probably most of them are failing, but few people are noticing.
There is room to make this part stronger which is disappointing.

So I took apart my MSM diff that was in the car, and was surprised to find that the pinion preload, was almost 0 in/lb, and the backlash was way over spec at .007".
I don't recall this diff making any noise, but the previous one I had in my car did. Anyway, after communicating with a couple of forum members who have either had work done, or
done it themselves, I have decided to have a go at assembling it myself. At least this way I will be directly responsible for the results, which I understand are not always positive.

Here are some of the dimensions of the parts in these 2 diffs. The pinion spacer was the same thickness on the 3.63 diff compared to the 4.1 diff.
Comparing the new crush sleeve thickness to the ones I removed, it looks like you crush the sleeve by about .050". I have shims would fit.
I wonder if I could have reused an old crush sleeve with a couple .007" shims.
I didn't realize the 3.63 pinion gear would be so much smaller than the 4.1.
https://cimg6.ibsrv.net/gimg/www.mia...982d321dac.jpg

And this is Max, who like most cats, likes to get into things.
https://cimg3.ibsrv.net/gimg/www.mia...cd9cce6c61.jpg
Next up is to re-assemble the diff, once I get the large pinion bearing in.

I'd not seen a picture of the inside of a Fuji before, but now I have I can fully understand why those tabs end up being broken off.

Interesting that the 4.1 pinion is bigger than the 3.6? If the ring gear is both the same 7" size on both then surely its the 3.6 pinion that has to be be bigger to achieve the longer gearing? Or is commenting before having a morning coffee doing me wrong here?

hen I built my diff I never had two of the pinions out at the same time to compare.

Good tip on the Dayco part finder! Very useful :bigtu:

Are you going to a solid pinion spacer with shims? Its my belief that anyone breaking 1.8 diffs that aren't breaking the small gears in the torsen are crushing thy crush sleeve over time which causes the pinion bearing preload to loosen up and makes worse tooth contact.

No, you're right Tchaps, thanks for correcting me on that. The 4.1 has 41 teeth on the ring, and 10 on the pinion while the 3.6 has 40 teeth on the ring and 11 on the pinion. The pinion gear needs to be bigger.

I am still just using a crush sleeve Leafy. Googling this didn't reveal how a solid spacer works to stop pinion preload loss. Some say this reduces preload loss but others say it's not true.
I have no experience or knowledge on this, so I decided to just go with the standard Miata part.
The commonly referred to advantages of a solid spacer on the internet.
1. You can replace the outer seal without worrying about preload.
2. You can tighten the pinion nut to any torque without changing preload.
The commonly referred to advantages of a crush sleeve on the internet.
1. Quicker to set up (unless you over crush the sleeve)
2. You can increase pinion bearing preload later, without removing the diff from the car.

I agree with Leafy.

In short, gears cam apart under load due to the contact angles on the face of the gears.

Some of that load pushes on the soft spring (the crush sleeve, designed to be weak enough to bend during installation to make setting preload easy).

If you push that spring too much, it bends permanently, resulting in a loss of preload.

A solid spacer is stiff enough that it won't bend permanently under load. Thus maintaining preload.

But more importantly, maintaining tooth engagement under load.

It would not surprise me if after setting preload with a stock crush sleeve, a single load event with high enough magnitude could yield that crush sleeve, resulting in a reduction or loss of preload.

I run solid pinion on my ford 8.8. Was a giant pain to shim it right.

Also, pretty sure I have a solid pinion kit for a miata diff if you're looking for one, I bough it years ago for the miata diff and never used it.

[QUOTE=oreo;1599519]No, you're right Tchaps, thanks for correcting me on that. The 4.1 has 41 teeth on the ring, and 10 on the pinion while the 3.6 has 40 teeth on the ring and 11 on the pinion. The pinion gear needs to be bigger.

No probs mate, sorry thought I was going mad. Intrigued to see the solid pinion spacer if you do go that route. As Pat said I can imagine it being more of a PITA to get correct and set up in the first place but if the torque demands it then might be a good addition, particularly for your Autosolo use with regular hard launches.

My knowledge of differentials is well, limited.

Pat
Can you tell me what torque levels you need to be at for this modification to be required/beneficial?
Can you help me understand better, why there is force on this crush washer?

If the crush spacer got crushed, would that change the preload?

As far as torque level, the only one that matters is torque at the pinion. So you could probably break it with stock power with a strong enough clutch, slicks, and a good launch.

The force is created by the tooth geometry on the gears. It's desired to only create forces that cause the pinion to rotate. But in practice, the teeth have to be able to spin and not run into each other while doing so. Thus, the teeth have an angle cut on them to allow clearance for rotation. This angle causes the force to act in 3 dimensions. There's an normal force at the face, and then resultant forces in X, Y, and Z. Some of those forces push against the pinion, which then transfers that load through a load path into the pinion bearing.

It's kind of like how a camshaft lobe pushes a lifter when the cam rotates. The gears are also trying to cam away from each other due to the contact angles. Same concept on gears, but to a lesser extent since that affect is not desired on gears but is unavoidable to some extent.

That's why the gear assemblies have to be both strong (to deal with load) but also stiff (to maintain geometry) so that wear is low, noise is low, efficiency is high, and strength through design geometry is maintained.

Yes if it gets crushed you will reduce or loose all preload.

Pat. Thanks for taking the time to post your thinking on this.

I'm with pat. I also believe that crush sleeve crushing is what kills 1.6 diffs with stockish power levels.

Is setting a crush sleeve really that easy? I've only build diffs with solid spacers and it only takes a couple trys to get it perfect. You only get 1 shot with a crush sleeve.

All about having the right tool for the job and a ready supply of satsumas.

https://cimg2.ibsrv.net/gimg/www.mia...3fa8ef15bc.jpg

Honestly, the only things I can see that would change pinion preload after it has been set are:
-bearing wear
-pinion nut loosening
-pinion shaft stretching
-housing deformation

Having said that, it would probably be pretty easy to machine a collar that would do the job. I will likely do that.

Tchaps Haha, is that the right tool? Actually I have seen others use similar set ups. -I have a small beam torque wrench.