No more broken throttle shafts
 

When I began driving CSP Miatas, I heard of throttle shafts breaking at the butterfly screws, the engine ingesting the screw and the next thing to do is rebuild the damaged engine. The guys I knew would weld, braze, or even JB weld the screws to the throttle shaft. Pretty insane considering you are spending good money on a pro built engine then protecting it with JB weld.


So, I personally have had two throttle body's shafts break on me in the past two years. We usually would carry a spare. The latest one broke during the El Toro pro. Lucky for us, Tom had welded the screws to the shaft. The engine was saved but runs were lost. After this event I had enough of the same problem. I took pictures and was just going to copy Bill's throttle setup and run the Skunk2 throttle body. I called Bill and he told me to call Skunk2 directly and see if the throttle body that they had in the works was finally going to be built.

I am thrilled to say they are making exactly what we all have needed for years. A Miata specific throttle body with a throttle shaft that won't break! It is 64mm, instead of the stock 55mm. When we would use our factory stuff and would clean up the inner lip, it would then show hp gains on the dyno, so I can't wait to see what this increased diameter will prove on the dyno. They use all factory components/sensors for 1.8L NA and NB cars.

Tom just got the prototype for us to test. I will post up improvements after putting it on the dyno. As far as I'm concerned if it makes the same power AND will stay together it's a win!


Hopefully this will save someone else's engine,
Scott Fraser

:useless:

I'm not a pro racer at all. But, not once have I ever had a butterfly screw come out. Not on Subaru sandrails, not on Porsche's, bikes, or anything. I am willing to be proven wrong, please do. However, not once in my years has a perfectly good throttle just come apart. Bad assymbly maybe? Dumb people? I pulled screws out of race car oil pans before, never even once thought buttterfly screw. I was another shop dropping carb screws in a open motor.

It is a known problem with the miata throttle body. I know emilio has a few posts about it, I am believe it has happened to Braineack.

Great! Give it two years for the chinese to copy it and find them for cheap on ebay :)

To be fair, I screwed with them.


HAHAHAHA get it, screwed with them. the screws, i screwed with them.

HAHAHAFDhsaKFjsakf;dsa d dsaf:party::party::party::party:

I saw the words "shaft" and "screwed" and came as fast as I could.

Stop screwing your shaft brain

I've seen a DP Miata ingest a throttle screw and the results was not pretty. I've talked to a guy that builds Spec Miata and other race cars about what to do on my car. His opinion on why the throttle breaks is the gas pedal and cable are not properly adjusted. After checking it on my car, I'd have to agree he has a point.

It seems the stop on the gas pedal is not very strong. You can actually flex the pedal and bracket when you really mash it. Once you get the throttle to fully open any extra pull from the cable is still getting applied to the shaft. It is this twist that fatigues and eventually breaks the shaft. His solution is to either put a better stop on the pedal once you get to fully open, or adjust the cable to have enough slack.

I had a friend push the pedal as I watched the throttle and shaft. It did look like there was more pull after the throttle fully opened. I adjusted the cable so that there is a little more slack and less tug after the floored position.
After pulling the pedals during the off season upgrades last year, the whole side of that thing for the gas pedal is pretty flimsy. I think I'll be reinforcing the stop on the bracket the next time I have some down time.

In for a reasonable price.

Less posting before coffee kicks in.

i dont drink caffinated coffee.

I was always under the impression the screws/shaft failed because the throttle cable tension was not set properly. So at full throttle the shaft was actually being twisted/loaded instead of the throttle cam hitting the stop.

AAAANNNNNNDDDDD... here it is! http://www.good-win-racing.com/Mazda...v_source=News1

https://www.miataturbo.net/attachmen...ine=1340741202

srsly 300 bucks for a throttle body? what are we, bmw owners?

A little on the pricey side, and nothing for 1.6's? :facepalm:

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Red loctite is overpowered

A broken throttle shaft nearly destroyed the $4000 motor in Rover a few weeks ago. I would pay a lot more than $325 to ensure that I never broke another throttle shaft ever again.

I'm hoping that in addition to not destroying engines, it actually makes some power an/or has other performance gains... anybody know what they are?

the one goodwinn sells suposedly gains like 5hp or something.
but 300+ is pretty steep for anyone that doesn't have a racecar like sav and a few others.

If Skunk2 sells it, it's more than likely made somewhere in Asia already.

After seeing how Skunk2 acts in the Honda community, I am not surprised they're trying to find some new customers. Doing ---- like this kind of killed their reputation in the Honda world:
https://www.miataturbo.net/attachmen...ine=1341020277

thats awesome

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It ended up in a lawsuit against a cam manufacturer/former owner of k20a.org (Nikos). I would post more details but based on how sue happy Skunk2 has been, I'd rather not get some detail wrong and get named in a case. This thread has all the details of the law suit: Skunk2 v. K20A.org - Honda-Tech

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Put my Skunk 2 throttle body on tonight and it whistles LOUDLY at %10-%20 or so throttle opening, is anybody else getting that???

I'm wondering if it's just not matching up well with my DDM Stage 2 intake, the inner diameter of the intake pipe is 60mm so the air is going from 60 to 64 (throttle body) and then back down again at the lip of the intake manifold where it meets the throttle body.

I was also thinking it may be the really weird idle air intake setup, there's that weird adapter plate with the offset holes before the IAC itself that's creeping me out.

Any ideas???

whistles = leaks.

I honestly thought it was just ours or how I did the intake porting until last week at nationals.

It is not an air leak.

I am going to make a call today and ask the question.

Scott Fraser

looks likes others are hearing the same thing with it... n/m.

I've heard TBs whistle when they had a bad seal at the gaskets between the IACV and MAP sensors.

It's the idle valve. Nothing to be concerned about.

They also whistle when there's sharp corners at a specific angle (usually an accident while dremmeling).

Teeheehee!

I hadn't seen the honda-drama in this thread earlier. Skunk2 owns Kraftwerks who sold me my Rotrex. Now I'm less surprised at the lack of support.

Sav: you running one of these?

Spent a chunk of my day on the phone with Brian from Skunk 2 and in the end his tech guys said that there's no way around the whistling, it's the resonance from the hole that goes down into the idle valve like Savington said. Sort of like blowing 90 degrees across the open top of a glass beer bottle.

Piss poor design, then.

Here's the sound, for the record...

http://www.ciottiindustries.com/audio/Miata/Skunk2.mp3

I took it off and boxed it up today, hopefully I can find someone with a turbo car and $300 burning a hole in their pocket at Miatas in Boone :)

Not to hijack, but out of curiousity, if FM can develop a small adapter to use a 1.6TB on a 1.8, why can't someone just make the same adapter to use a common Ford/Chevy TB? Seems much more cost effective....

Obviously it's a need basis type thing. More people need the 1.6 > 1.8 adapters than the alternative. I highly doubt they would want to manufacture a plate that will be purchased by maybe 4-5 people.

I was under the impression that the restriction is directly behind the throttle body in the throat of the manifold? Wouldn't that give you similar gains?

Personally i think making a pipe that allows you to get rid of that ugly 2" bottleneck at the intake manifold is better.

Got one as soon as I could get my hands on one, yes. One junked $4000 race motor is one too many.

Sav, have you guys done any testing on that? A replacement for that ugly upper manifold piece?

? I don't know what you're referring to. A replacement upper intake manifold?

You know how the manifold is split into 2 pieces? The upper piece of the manifold has a wimpy 2" diameter bottle neck right after the throttle body.

The stock manifold does. The squaretop improves on that drastically, and any aftermarket intake manifold does as well. I have no idea why you would bother replacing the upper half when you could just change the entire thing and see even more of a gain.

OK so a replacement top half that is similar to the square top and has a throttle body flange for the small ford pattern (I used a $45 shipped 65mm crown vic TB. Included the TPS/pigtail & works with the miata throttle cable end). Should be doable for less than an entire new intake manifold. No whistle on the ford throttle bodies cause no IAC. bwahahaaha. Simple fix with another bracket.

Hmm whatever came of the top mount throttle body, intake manifold begi was working on? Sure probably looks funny but if it gets rid of the uneven flow why does it matter?

The whistles go "woo".

So lets say that I wanted to wait on buying one of these because of a lack of funds at the moment. Is welding or JB welding the screws on the stock one an acceptable temporary solution? Does it stop the engine from ingesting the screws or does something else get swallowed when the throttle shaft breaks?

Use two-part epoxy. I do it on throttle bodies and VICS butterflies.

Have the VICS butterflies been known to fall apart, or are you just being extra-cautious?

Is JB weld basically a two part epoxy or am I about to make a horrible decision?

Yes, JB Weld is 2 part. It's also one of the best available for metals.

Here is the throttle body on my 1.6 car. It is also available in the 1.8 version. Last I checked cost was $ 410.00 plus a core.

https://www.miataturbo.net/attachmen...ine=1350520678
https://www.miataturbo.net/attachmen...ine=1350520678

$400 is expensive for a throttle body but whats an engine cost?

Uck for 400 bucks i'll look for alternatives

Not to be a dick, but this is basically what everyone who's never broken a throttle shaft is going to say. I have a $4000 built motor in pieces in the shop because it ate a throttle screw - I would have gladly paid $1000 for an upgraded throttle body a year ago had I known it was going to break 8 hours after installing that motor.

If you don't think it's worth $300 or $400 or whatever, just wait until you're replacing a motor because your OEM TB broke. That's usually pretty convincing.

Pretty sure I remember Emilio saying in a post that he does this on his track cars and hasnt had a TB shaft failure since

Throttle shaft breakage - Page 6 - MX-5 Miata Forum

post#140

A lot can happen in a year.

Does this happen to the 1600 TB as well?