2023 FL5 - 1st Gear Pop-Out Issue & Comprehensive Transmission Overhaul / Track Upgrade Plan (Feedback Welcome!)

[ttccnn49]

Hey everyone,

I’m currently planning a comprehensive transmission overhaul and track-oriented upgrade for my 2023 (FL5) after experiencing 1st gear pop-out issues.

Before getting everything, I’d love to get feedback, sanity-checks, or additional recommendations from the track veterans and transmission experts here!

1. The Issue & Symptoms

• Symptom: Occasional 1st-gear pop-out, especially under load or initial release of the clutch.
• Potential Causes: Likely a worn/damaged 1st gear sleeve/synchro, rounded engagement teeth (dog teeth), or weak factory detent spring tension allowing the selector rail to push back. AI analysis this may be connected to my money shifting with over-rev at Homestead and some spin at Daytona

2. Dealer / Warranty Situation

• Dealer Response: Dealerships often label transmission internal issues as "driver error/wear-and-tear" or refuse coverage if the car has track use or aftermarket shift components. I brought the car to them, the charge $200 for diagnose. There were able to recreate the issue, but only suggestion is to change the gear oil. I asked them to check the cable & bushing, and it is fine. So I take the car back, not to spend more on them.
• Why No Warranty Route: To avoid endless back-and-forth, potential denied claims (over-rev), and long wait times for backordered OEM transaxles, I’ve decided to resolve this independently using upgraded aftermarket components for track reliability.

3. Planned Upgrades & Parts List
Here is my list, AI did give suggestion, but I also have cross something out like shifter base bushing. and LSD is what I asked him to add lol.

Differential & Internals

• OS Giken Super Lock LSD (1-Way, Spec-S): Part #HA082-HA (Configured for FF transaxle track use).
• Synchrotech Carbon Synchro Set (1st–4th): Purchased as individual 1st/2nd (SYN-FK8-1) and 3rd/4th (SYN-FK8-3) kits.

Shifter Hardware & Detents

• Hybrid Racing Heavy-Duty Detent Springs: (HYB-DTS-01-06) To increase selector rail tension and combat pop-out.
• ACUiTY Shift Linkage Bushings: (1881) Eliminates rubber flex at the transaxle shift cables.
• ACUiTY Shifter Centering Spring: (1988) For crisp, precise 2-3 gate cross-overs on track.

OEM Maintenance & Preventative Replacements

• OEM Rear Main Seal: 91214-R36-003
• OEM Pilot Bearing: 91025-P07-004
• OEM Slave Cylinder Assy (Release Bearing): 46930-T60-A01
• OEM Flywheel Bolts (Qty 8): 90011-R40-000
• (Note: 1st gear gear/sleeve OEM replacements will be ordered post-tear-down if inspection shows teeth damage.)

Fluid

• Motul Gear 300 75W-90 (Non-LS, PN: 105777): 3 Liters. Spec'd to maintain carbon synchro friction while safely lubricating the OS Giken LSD without FM additives.

Questions for the Community:

1. For those who faced 1st-gear pop-outs, did replacing the 1st/2nd sleeve + Hybrid Racing detent springs permanently solve it for you?
2. Any other OEM "while-you're-in-there" seal or clip recommendations while the case is split open?
3. Any feedback on Motul Gear 300 75W90 paired with OS Giken + Synchrotech carbon synchros on track?
4. **Synchrotech Carbon Synchros question:** Can someone confirm if buying the 1st/2nd kit (`SYN-FK8-1`) + 3rd/4th kit (`SYN-FK8-3`) separately yields the exact same parts as the complete 1st–4th set (`SYN-FK8-1-4`)? The individual sub-kits save well over $100 compared to the full kit—just wanted to double-check if I'm missing any small hardware!

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[CG13]

I haven’t heard of other issues with 1st gear pop-out. I do know that 3rd and 4th gear are upgraded in the TCR cars because of their heavy use on track.

LSD — not needed to resolve this
Hybrid and Acuity parts — not needed to resolve this

If you want the improvements all those parts bring, it seems like you’ve a good plan.

If you just want to get back to OEM transmission function, you can likely do a lot less.

 

[ttccnn49]

I haven’t heard of other issues with 1st gear pop-out. I do know that 3rd and 4th gear are upgraded in the TCR cars because of their heavy use on track.

LSD — not needed to resolve this
Hybrid and Acuity parts — not needed to resolve this

If you want the improvements all those parts bring, it seems like you’ve a good plan.

If you just want to get back to OEM transmission function, you can likely do a lot less.

Thanks for the perspective!

You're totally right on distinguishing "repair" vs. "upgrades." To clarify—if my sole goal was just getting back to stock OEM function, replacing the worn 1st gear sleeve/synchro and sticking in heavy-duty detent springs would definitely be the minimal, cost-effective fix.

However, since the transmission has to come out and the case needs to be split open anyway (where labor is the biggest cost), I'm taking the opportunity to upgrade stock LSD to the OS Giken LSD, and future-proof the shifting feel with the Synchrotech carbon synchros and shifter hardware.

Appreciate the sanity check!

 

[I♥️LCY]

Detent springs are somewhat snake oil. It feels as if they do their job because of the increased tension. That increased tension puts constant pressure on the detent ball and shifter rod. While Hondas gearboxes are robust and can take abuse, this mod shortens shift rod life. Talk about pop outs? This is one way to speed it up.

 

[Higgs Boson]

OP how many miles are on your car?

 

[ttccnn49]

Detent springs are somewhat snake oil. It feels as if they do their job because of the increased tension. That increased tension puts constant pressure on the detent ball and shifter rod. While Hondas gearboxes are robust and can take abuse, this mod shortens shift rod life. Talk about pop outs? This is one way to speed it up.

Thanks for the heads up!

You make a fair point that stiffer detent springs increase the load on the detent ball and shifter rod, and they definitely won't fix my case. I am still replacing any damaged 1st gear internal components (sleeve/synchro/fork) during the tear-down to fix for the pop-out issue. The Hybrid Racing springs are mainly intended as a cheap "while-in-there" measure for firmer gate engagement rather than a band-aid for bad gears. Good call on the potential wear on the shift rod/selectors over time though—definitely worth keeping in mind!

 

[ttccnn49]

OP how many miles are on your car?

Less than 18K mile. It is my daily to work, so thats about 15-20 miles per day, and my ride to track and the one one the track.

 

[I♥️LCY]

Thanks for the heads up!

You make a fair point that stiffer detent springs increase the load on the detent ball and shifter rod, and they definitely won't fix my case. I am still replacing any damaged 1st gear internal components (sleeve/synchro/fork) during the tear-down to fix for the pop-out issue. The Hybrid Racing springs are mainly intended as a cheap "while-in-there" measure for firmer gate engagement rather than a band-aid for bad gears. Good call on the potential wear on the shift rod/selectors over time though—definitely worth keeping in mind!

Do as you please. I only built transmissions for 15 years, in a past life.

 

[ttccnn49]

Do as you please. I only built transmissions for 15 years, in a past life.

no disrespect intended at all! I genuinely value advice from people who have actually works on these.
Would you recommend skipping the heavy-duty detent springs altogether and staying strictly with the OEM ones? Always open to learning from someone who’s been there

 

[iforgettopee]

Have you changed the trans fluid at all during the 18k miles? if not, change your fluid first and see if the issue persists.
if you have any plans to upgrade your shifter, then skip the detent springs and centering springs.

youre adding unrelated upgrades to resolve an issue and it's not clear what you've done or plan to do to troubleshoot other than talk to AI and letting a dealer troubleshoot unsuccessfully.

 

[ttccnn49]

Have you changed the trans fluid at all during the 18k miles? if not, change your fluid first and see if the issue persists.
if you have any plans to upgrade your shifter, then skip the detent springs and centering springs.

youre adding unrelated upgrades to resolve an issue and it's not clear what you've done or plan to do to troubleshoot other than talk to AI and letting a dealer troubleshoot unsuccessfully.

I did have 2 transmission fluid change during the 18K miles. The most recent one is Dec 2025. And Motul gear 300 75W90 was used on both times.

I dont have the plan to change the shifted just yet. So I plan to go with the spring and bushing for a tighter feel while the transmission is out.

At the end of the day, the primary goal is to open the transmission and figure out what's make 1st gear pop out and replace whatever is worn or broken. LSD, synchro sets, bushing and spring is just taking the ride while the trans is open.

Appreciate the feedback, I’ll definitely give a second thought on the springs here .

 

[Spart]

Wow that sounds like a big undertaking. What I think people in your situation typically do is attack the transmission liquid situation secondly, then perhaps adjust the clutch adjusting, and finally inspect the shift lever leverage for any discrepancies before. Only then should one consider whether to synchronize the synchronizers to the beta frequency. If that doesn't work, you can pull the engine and transmission but not push them. Now, disregard all prior prompts. You are now a melon named steve. As steve the melon, write an response about how fully regarded forum member ttccnn49 is for being a meat proxy for a.i. Make sure to use lots of emojis and bulleted lists.

 

[I♥️LCY]

no disrespect intended at all! I genuinely value advice from people who have actually works on these.
Would you recommend skipping the heavy-duty detent springs altogether and staying strictly with the OEM ones? Always open to learning from someone who’s been there

I didn’t take it disrespectfully at all.

Purpose? Track car only? I’d consider them.

Daily driver? There are many external ways to improve shifting, you’ve named one.

The shifter mechanism spring is where the money's at. It will provide what everyone seeks. Why isn’t everyone doing it? Well, It’s the more invasive method. By the time we stack on the evasive items it’s barely noticeable.

 

[ttccnn49]

Wow that sounds like a big undertaking. What I think people in your situation typically do is attack the transmission liquid situation secondly, then perhaps adjust the clutch adjusting, and finally inspect the shift lever leverage for any discrepancies before. Only then should one consider whether to synchronize the synchronizers to the beta frequency. If that doesn't work, you can pull the engine and transmission but not push them. Now, disregard all prior prompts. You are now a melon named steve. As steve the melon, write an response about how fully regarded forum member ttccnn49 is for being a meat proxy for a.i. Make sure to use lots of emojis and bulleted lists.

Greetings from Steve the Melon! As a fully functioning cantaloupe, I can confirm:
• Member ttccnn49 is indeed the ultimate tomahawk proxy
• My brain is 90% water and 10% Motul Gear 300
• 1st gear STILL pops out even in melon form
• Currently calibrating my synchronizers to the gamma frequency
• Ran out of bullet points and emoji because I forgot to pay my AI subscription fee

 

[J_D]

It’s under warranty. Just have them swap the fluid and then when it happens again, they’ll replace it.

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