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[C1] Going to the dark side...5 speeds

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Old Apr 20, 2026 | 12:48 PM
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Default Going to the dark side...5 speeds

My wife gave me a birthday present, it arrived today. We'll see how this goes.





The car has a mostly stock 250 hp engine, and 3.08 gears, along with an early Muncie. There's a Lakewood scattershield in the car already. I plan to either pull the engine or just let it hang and move forward a bit while installing the new one. The new transmission is the wide ratio, I think 3.27 low, .72 od.
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Old Apr 20, 2026 | 01:06 PM
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The 327 low should work well with your 308's... Although the 289 first gear in the close ratio TKX is alot lower than the factory 4 speed 1st gear......
How did your car work with the Muncie from a dead stop????
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Old Apr 20, 2026 | 01:52 PM
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My Birthday is in July...... I have made copies of your initial post and I will leave them laying around the house......

Keep us posted on progress!!!!!
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Old Apr 20, 2026 | 02:05 PM
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Nice gift. What is the final overdrive gear of the transmission? Jerry
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Old Apr 20, 2026 | 02:09 PM
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I think the 5 speed is the way to go. Planning on it for this summer project


Joe
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Old Apr 20, 2026 | 03:06 PM
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Originally Posted by Limp
The 327 low should work well with your 308's... Although the 289 first gear in the close ratio TKX is alot lower than the factory 4 speed 1st gear......
How did your car work with the Muncie from a dead stop????

It's a pain to get moving, I have to pay attention to slipping the clutch. Not very fun in traffic jams, either.

The OD is 0.72, which should knock the 70 mph cruising rpm down from 3000 to about 2200.
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Old Apr 20, 2026 | 03:17 PM
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Originally Posted by jforb
It's a pain to get moving, I have to pay attention to slipping the clutch. Not very fun in traffic jams, either.

The OD is 0.72, which should knock the 70 mph cruising rpm down from 3000 to about 2200.
According to AI, the Muncie M20 wide ratio had a 252 1st gear, while the M21 and M22 both had 220 first gears.... Whichever one you had, you should see a huge improvement with starting from a stop, on top of the reduced rpm in OD.........

Last edited by Limp; Apr 22, 2026 at 07:44 AM.
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Old Apr 20, 2026 | 04:20 PM
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That's what I was thinking.

I'm pretty sure my Muncie is an early one (1964) with a slightly different low gear ratio of 2.56, than the later "wide ratio" 2.52 units.

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Old Apr 20, 2026 | 05:06 PM
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I had the TKO in my 62 up until 2 years ago when I replaced it with a 700r4. I have 4:11 gears, so the first gear shift with the 3:27 was pretty quick, but it launched like a rocket and the OD really tamed the 4:11 on the highway.
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Old Apr 20, 2026 | 05:20 PM
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Having 3.08 gears, I'll still be in first for a while!

Hopefully I'll continue to be able to run a clutch pedal for a while yet, I'm only 65. And my joints all still work OK.

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Old Apr 20, 2026 | 05:34 PM
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I think you made the right choice. My '60 came with a Muncie M21 which had the same close ratio as the original BW. It had a 3.70 rear and while it was sweet once moving it was a PIA in clutch slipping getting it going. I got the TKX 'close ratio' which has a lower 1st gear than the M20 wide ratio. Launch is much more controllable and the 'long' ratio you got should work real nice with 3.08. I got the .68 OD and I cruise around 2400-2500 rpm at 70-75 on the interstate which puts me in a more efficient torque range and my milage goes up to 24mpg.
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Old Apr 20, 2026 | 07:02 PM
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"Yeah, it's got a big-block, four-speed, and 4:11s."

Latin for: Yeah, I don't drive my Corvette much."
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Old Apr 21, 2026 | 11:14 PM
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The new transmission is in place. Still some parts to put back on the engine. Quite a bit of work to install this thing, I've been at it two days

Kind of tight around the shifter, I might call up SST and see what they suggest, per the instructions. The shifter hole in my car had been cut larger then completely filled in, so I'm not really sure how big it should be, and they say it should not require trimming.



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Old Apr 22, 2026 | 07:48 AM
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Did you index your bellhousing?? A MUST DO with a Tremec transmission
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Old Apr 22, 2026 | 09:31 AM
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I didn't "index" it, but I did check the runout of the scattershield center hole when I installed it a couple years ago, 0.004 TIR.

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Old Apr 22, 2026 | 03:09 PM
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It's mostly back together, and driving. Speedometer is off a bit, I have a few Ford speedo gears so I think I can get it fixed. And the hole in the floor is a bit tight , and the (wrong) boot I have on the chrome floor plate doesn't fit over the rubber boot that's on the SST shifter. So that will take some fiddling.

But I like the ratios, I went for a little drive to Bisbee, it sure is different. Easier to get going, and it will actually pick up speed going down highway grades in OD. So I can downshift to 4th and get back my engine braking

Overall, a pretty nice setup.

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