Muncie popping out of 3rd gear at 6100 rpm...650 wtq - Chevelle Tech
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post #1 of 16 (permalink) Old Jul 16th, 19, 1:22 PM Thread Starter
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Frank
 
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Muncie popping out of 3rd gear at 6100 rpm...650 wtq

I have an M23 I bought new a few years back. I don't have many miles on it and it never did this before in another setup so its something I have setup wrong I suspect.

Details on setup
3400 lb race weight car
LS3 turbo about 650 wtq 12psi
M23W 1.48 3rd gear
Center force DFX 6 puck ceramic single disk clutch
3.08 rear gear and 28" MT Pros
New Hurst shifter


When I first got the trans new, I had 3rd gear limiter on the shifter way too far out and ground 3rd gear a few times pretty bad, not sure how I was that inept looking back at it. Maybe I tore up 3rd gear a little doing that, I cant imagine though, it was only a few times. I adjusted the limiter out a turn and a half, it doesn't grind, but still pops out, I'll try adjusting it further but I have to be close to making it grind again.

My other theories are I need offset dowels in the block, I never measured concentricity...would that do this? It doesn't pop out in 1st or 2nd, but its never hooking in those gears at all under load so not a good comparison.

The pucks on the clutch look a little crappy, slightly pitted, the ceramic disk does not like 3.08 gears and 28" tires, I have to slip it more than a ceramic disk should be slipped just driving around. Could the clutch make it pop out? It is holding the power fine, I can do a pull in 4th gear to 145mph and it never slips, but thats only to 5200 rpm or so.

So my theories, what do you think:
1. Third gear limiter on the shifter still too limiting
2. Tore up a gear or synchro by grinding 3rd gear a few times
3. Concentricity is off <--- I feel like this might be it but then again I keep reading that will tear up trans bearings more than anything
4. Clutch somehow

Thanks for any insight! I have a dyno appt on Friday so I am desperately trying to figure it out, I want to dyno in 3rd to 7200 rpm, 4th would put me over 200mph so thats not great.

64 Chevy II, L92 6.0, 57mm S200s, AWD with Syclone/Astro transfer case

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63 Impala, 454ho short block, 265 afr heads, 60mm S300s
62 Biscayne LS3 turbo, M23
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post #2 of 16 (permalink) Old Jul 16th, 19, 5:26 PM Thread Starter
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Frank
 
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

Just got under there to check the linkage/arms, and the lever that is bolted to the transmission was slightly loose, not sure how that little bolt going into the trans mechanism could come loose, but Im really hoping that was the issue! Doesn't seem like it since if the shift linkage was on the X axis exactly, the movement due to the loose bolt was on the Y axis, perpendicular to the linkage/arm throw, but sure seems suspicious!

64 Chevy II, L92 6.0, 57mm S200s, AWD with Syclone/Astro transfer case

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63 Impala, 454ho short block, 265 afr heads, 60mm S300s
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post #3 of 16 (permalink) Old Jul 17th, 19, 12:27 AM
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

The unfortunate answer is in the first 10 minutes of this video. The combs inside the trans determine how much the fork will move to engage the gear. You can remove the stops altogether and still get no more movement or engagement. If the shifter is moving the lever into the 3rd gear comb detent and the trans is still kicking out of gear, your issue is internal. The only thing you could possibly repair without disassembly of the trans is worn out shift forks.

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post #4 of 16 (permalink) Old Jul 17th, 19, 12:47 AM
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

Bellhousing alignment could cause damage to syncros and gears. If bellhousing alignment is off, it could hamper full disengagement of the clutch resulting in damage to the syncros or gears because they have to work harder to get the gear speeds matched to complete the shift.

Typically, you'll also have other tell tale signs if bellhousing alignment is off. Tough shifting, grinding into first or reverse, pilot bushing destruction, increased syncro wear rate, bent disc, and failing input shaft bearing to name a few.
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post #5 of 16 (permalink) Old Jul 17th, 19, 7:29 AM
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Gene
 
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

Did you call Nathan or George at Autogear? Since they build them, they may offer a better clue.

Gene
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post #6 of 16 (permalink) Old Jul 18th, 19, 12:26 PM Thread Starter
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Frank
 
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

Typed out a long message then wasn't logged in and lost it. Anyway, I fixed the lever on the 3-4 shifter node, put a new shift lever on, the old one was the slightest bit bent. That didn't fix it. It holds to 7000rpm no problem on 5psi but at 12psi it still pops out around 6100. I suspect my bell housing alignment is really far off. I am going to call Nathan and see what he thinks, or might just pull it out and measure concentricity first.

Thanks for all of the replies and the video!

64 Chevy II, L92 6.0, 57mm S200s, AWD with Syclone/Astro transfer case

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post #7 of 16 (permalink) Old Jul 18th, 19, 1:39 PM
blm
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

If you do end up needing offset pins I would use the pins from Mcrobbperformance. They are a breeze to install. However removing the old pins with the engine installed can be quite the chore. Here is a thread from when I did them on my 396.

https://www.chevelles.com/forums/33-...n-removal.html
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post #8 of 16 (permalink) Old Jul 19th, 19, 1:33 PM Thread Starter
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Frank
 
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

Thanks for the link, those offset pins do look a lot easier to deal with!!

I took it to the dyno and it stayed in gear to 6600 rpm and showed 721 wtq so either it likes being super warmed up or the drum weighing a lot less than the car helps it stay in gear. I let out at 6600, it did not pop out.

Im going to pull it out next week and take a dig around inside and will update here, thanks for all the help!

Other than popping out of gear (because of something I goobered up Im sure) this is the best shifting manual trans Ive ever driven.

64 Chevy II, L92 6.0, 57mm S200s, AWD with Syclone/Astro transfer case

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63 Impala, 454ho short block, 265 afr heads, 60mm S300s
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post #9 of 16 (permalink) Old Jul 25th, 19, 10:51 AM Thread Starter
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Frank
 
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

The insides of the trans look new to me, I cant see any synchro or gear chipped or beat up at all.

Thats a big relief after my grinding 3rd when I first got it due to shifter adjustment being out and then
the popping out of gear under power I was wondering if that was tearing something up.

Im going to check the concentricity next and see if that is off.
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64 Chevy II, L92 6.0, 57mm S200s, AWD with Syclone/Astro transfer case

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post #10 of 16 (permalink) Old Jul 25th, 19, 12:03 PM
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

5 psi? this a hydraulic clutch>?

Gene
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post #11 of 16 (permalink) Old Jul 25th, 19, 12:36 PM Thread Starter
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Frank
 
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

Yeah 5psi and 12psi refer to turbo, sorry not more clear on that. I was trying to say on lower power it stays engaged but higher power is when it pops out of gear.

Looking at it I don't see how it could be popping out of gear under load unless something is acting on the slider, its so weird.

It is a hydraulic clutch, Im using a Howe hydraulic throwout bearing.
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64 Chevy II, L92 6.0, 57mm S200s, AWD with Syclone/Astro transfer case

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post #12 of 16 (permalink) Old Jul 25th, 19, 1:20 PM Thread Starter
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Frank
 
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

Yeah 5psi and 12psi refer to turbo, sorry not more clear on that. I was trying to say on lower power it stays engaged but higher power is when it pops out of gear.

Looking at it I don't see how it could be popping out of gear under load unless something is acting on the slider, its so weird.

It is a hydraulic clutch, Im using a Howe hydraulic throwout bearing.

64 Chevy II, L92 6.0, 57mm S200s, AWD with Syclone/Astro transfer case

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post #13 of 16 (permalink) Old Jul 25th, 19, 3:24 PM
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

I was assuming line pressures ought be WAY more than that, thank you.

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post #14 of 16 (permalink) Old Jul 27th, 19, 2:58 PM Thread Starter
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Frank
 
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

It measures .009 out at the most. I'll put some .007 Robbmc offset pins in and see how that works. Thanks for all the replies and help.

64 Chevy II, L92 6.0, 57mm S200s, AWD with Syclone/Astro transfer case

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63 Impala, 454ho short block, 265 afr heads, 60mm S300s
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post #15 of 16 (permalink) Old Jul 27th, 19, 4:16 PM
blm
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Re: Muncie popping out of 3rd gear at 6100 rpm...650 wtq

Think .009 is within limits. Probably being .009 is not the issue.
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