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Discussion Starter #1
Hey everyone.

I recently had my S40B000 d16 transmission rebuilt. It already had a Quaife LSD. I've installed an MFactory 3rd and ZC 5th and used the Synchrotech Carbon Synchro rebuilt kit.

The mechanic that's reinstalling the transmission said that it will not stay in reverse. He said:

"The reverse gate seems blocked. You can get reverse idler to engage slightly by keeping pressure on the shifter in the reverse position, but the shifter will return to neutral the moment you take your hand away."
"But even then, reverse idler barely engages the gears on the main/counter shaft."

He suggested that perhaps the idler was installed incorrectly.

I contacted the gentleman that rebuilt the transmission for me. He said:

"Remind him no lube has been run in unit. And have to use what your new synchro call for." - not sure what this is exactly. I need to look that up.

He also said:

"New synchro have material on them and with no lube will be stiff. The lube I put on prob ran off by now"

Regarding the idler, the transmission tech said they can go in "either way". My mechanic isn't so sure.

Any idea what might be going on?

Thanks.
 

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wow i dont even know where to start, sounds like the gear for reverse was installed upside down somehow? or more likely the pin wasnt engaged when the reverse shift fork was installed.
 

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Brokedick Millionaire
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Guess the rebuilder is coming there to R&R the trans and crack it open? If he didn't know it only goes in one way....then he didn't bench test it either.
 

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Discussion Starter #4
My mechanic is going to investigate the issue further. If necessary, he can remove and examine the transmission. The alternative option being that it's done by the gentleman that did the build.
 

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Discussion Starter #5 (Edited)
I'm trying to squeeze in a little research to understand more clearly what the idler gear does. From what I understand, it's an intermediate gear that transfers the rotation of the main shaft (I believe) to the reverse gear. It essentially reverses the direction of the rotation.

Sounds about right?

To my inexperienced mind I would imaging that there's a specific orientation of the gear teeth which is necessary for it to serve its purpose. Otherwise I would imagine the teeth of the gear and the other components it interacts with would cross rather than interlock. Sounds like a good way to damage the gear teeth.

Hmmm... Took a look at some pics of Honda reverse idler gears. They look like straight-cut teeth.

Someone want to educate me on this?

Would the idler gear affect any the function of the forward 5 gears?
 

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sounds like rebuilder is unsure, or is so busy he already forgot your specific service.


I say let the mechanic pop the tranny out, send it to the rebuilder, and hopefully you will not be out of pocket more for another removal/reinstall


ask the rebuilder to verify function before giving back.


when you pay good money for someone to professionally rebuild something, the least they can freakin do is check their work before sending it to the shop to be installed
 

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Brokedick Millionaire
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The idler teeth are only beveled on one side. I have never installed one backwards, simply because the first trans I watched get split apart and I split my first that night as well.

HYBRID: Installing an Si FD into a ZC Transmission

I have put the 1-R-2 slider on upside down when doing B series, but always catch that when try to drop the gear stacks in.
 

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Hmmm... Took a look at some pics of Honda reverse idler gears. They look like straight-cut teeth.

Someone want to educate me on this?

Would the idler gear affect any the function of the forward 5 gears?
reverse is straight cut no synchro thats why it clunks in gear and whines when you are going fast in reverse
 

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Idler only goes in one way. Unless he used water it didn't run off the synchros.

He should have told you what fluid to run.
 
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Hey everyone.

It's me, Curlybandit, the OP.

I've recetly learned that there has been a password reset going on for the DSO members and unfortunately I'm no longer able to access my Curlybandit account. I've set up this temporary account so that I can finally respond. I've already attempted to contact the admin. Hopefully they sort this out soon.

Some updates: I've since been in communication with the rebuilder. He has given me his assurance that the idler gear has been installed correctly. He also acknowledged that reverse doesn't have a synchro. He suggested that the cause of the problem could possible be a synchro from another gear making it difficult to shift. He also confirmed that he bench tested the transmission after it was reassembled. I'll be following up with the mechanic reassembling the car later today.

Regarding the fluid, I received a response from Synchrotech. They've confirmed that Honda MTF is fine but of course recommended their MTF fluid.
 
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A synchro on another gear won't affect it shifting into and staying in reverse.

Don't run Honda MTF.
Just got this very detailed response from David of Synchrotech on another forum:

"A synchro would not affect it staying in reverse. Reverse in engaged on this trans when the shift fork linkage moves the reverse fork to engage the idler gear (no synchro is involved here on the S40 trans). If it does not test shift properly on the bench in all gears including reverse, it needs to come apart to see what is wrong."

Reaffirming what you've just posted. The hunt continues.

Which fluid do you recommend instead? I've used Amsoil synthetic MTF before in this transmission when it was first seapped from AT to MT. Worked very well.
 

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Tape-R taper/driver
EC3, ED8, ED9, EE5
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A synchro on another gear won't affect it shifting into and staying in reverse.

Don't run Honda MTF.
Never had an issue with Honda's MTF, even in endurance racing. The trans gets the oil changed once a season.
 

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Needs to be changed way more often than that. If you had it analyized afterwards and inspected the trans you would likely have a different opinion.

I recommend Torco. MTF for street cars, RTF for track cars, boosted cars and high RPM NA setups.
 

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Discussion Starter #18
Was speaking with my mechanic this evening. He said the transmission shifts into 1-5 as it should. Reverse feels as though there is something physically or mechanically preventing it from going into the gate. He said he will test the linkages once more this weekend but failing that he will have to remove the transmission so I can take it back to the rebuilder to get it sorted out.

Not too impressed... But needs to be done.
 

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Brokedick Millionaire
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Put the car in the air with someone in the drivers seat. Disconnect the linkage from shift shaft and do all shifting by hand AT the trans, thus eliminating the linkage/mount issues.
 

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Brokedick Millionaire
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Never had an issue with Honda's MTF, even in endurance racing. The trans gets the oil changed once a season.
Which version of Honda MTF? I have a customer that bought a case or two of the early/good/stinky stuff, shifts great and last most of a season depending on number of events entered.

Also had a local rebuild that complained a trans I rebuilt wouldn't shift right after 15 minutes of driving, but was fine cold. Turns out he was running the latest MTF from Honda. Switched to the 10w30 from Wally World and I only heard back "It's good now, thanks!"
 
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