[b-man]

My 4-speed 400 (standard 330 hp) Firebird had factory A/C with a 3.23 open rear.

Moved out pretty well with the 2.52 first gear, with a 2.64 it would have been great.

[TCSGTO]

3.08 with a 2.64 low 1st is about the same gearing as a 3.23 with a 2.52 1st. A lighter car but similar power, had a 68 AMC AMX 390 with a 3.15 rear and 2.20 low and it was not a fun car in stop and go driving. Changed to a 2.64 low T10 and it was night and day different. Could roll out from a dead stop in 1st with very little throttle.

[Tom Vaught]

Originally Posted by TCSGTO

had a 68 AMC AMX 390 with a 3.15 rear and 2.20 low and it was not a fun car in stop and go driving. Changed to a 2.64 low T10 and it was night and day different. Could roll out from a dead stop in 1st with very little throttle.

IMAGINE A 5 SPEED TRANS WITH A FIRST GEAR OF 3.27 AND A FINAL GEAR OF 1 TO ONE (with all of the gear splits (rpm drops) being the same.
I run a 3.27 trans and a 2.75 Ford rear gear and have the best of both worlds.

There are combinations like that with some aftermarket trans but the basic
Muncie 4 speed with a 2.20 1st gear is a poor choice for most applications, even with a 455 engine.

Tom V.

[Gary H]

As far as I can determine; numerically, the lowest gear ratio you can buy new for a 8.2 BOP is a 3:36. I think it is only made by Yukon. If you want a 3:23, 3:08 or 2 series gear ratio it will have to be used.

[dmac]

Going from a 26" tall tire to a 28" tire changes gear ratio from 3.55 to 3.30 according to Wallace racing Chart. Going from a 3.55 to a 3.36 AND getting slightly taller tires could get you pretty close to where you want to be.

Unless the car runs quiet, I hate highway driving at anything above the lowest rpm possible. Aiming for 2000-2400 rpm at between 50-60 mph is kind of a middle point if driving is split much between city and open freeway. And getting a little above 2500 rpm should get you close to max toque production, so passing/acceleration should still be decent

[The Champ]

Lee

I have a '64 GTO with it's original M20 with 2.56 1st gear and switched from 3.42 rear gear to a 3.08. My rear tires are 26.7" tall.

2.56x3.08=7.88 effective first gear.

I made this swap to reduce the RPM's on the Interstate, with the caveat that if I didn't like the result, I'd buy and M22Z with a 2.98 first gear. That was 3 years ago and I'm still running my original Muncie.

I'm 1.5 - 2 hours south of you if you or your friend wanted to drive my car.

I have to admit, I have been giving some thought to the direct fit TKX 5 spd which has either a 3.27 or 2.87 1st gear and either a .68, .72 or .81 OD depending on 1st gear ratio.

[leeklm]

Originally Posted by Gary H

As far as I can determine; numerically, the lowest gear ratio you can buy new for a 8.2 BOP is a 3:36. I think it is only made by Yukon. If you want a 3:23, 3:08 or 2 series gear ratio it will have to be used.

I was thinking the 3.08 gears were readily available for the 8.2 BOP, but after another quick search, you seem to be correct!

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[The Champ]

Just did some checking based on the fact that you say he can currently start in 2nd gear.

This is what I found for the 2.64 1st gear T10:

Borg‑Warner T‑10 2nd Design 2.64 1.61 1.23 1.00

With a 1.61 2nd gear and a 3.55 rear - the effective ratio is currently 5.72

[leeklm]

Originally Posted by The Champ

Just did some checking based on the fact that you say he can currently start in 2nd gear.



This is what I found for the 2.64 1st gear T10:



Borg‑Warner T‑10 2nd Design2.641.611.231.00



With a 1.61 2nd gear and a 3.55 rear - the effective ratio is currently 5.72

1.61 is the 3rd gear ratio. 2nd gear is a 2.1 ratio

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[77 TRASHCAN]

Exactly how much highway cruising, does your friend intend to do?

[The Champ]

Originally Posted by leeklm

1.61 is the 3rd gear ratio. 2nd gear is a 2.1 ratio

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2.1 apparently is the 2nd gear ratio for the Super T10 built from 1977 - 79

https://itstillruns.com/super-t10-tr...s-7713046.html

I was looking at the gear ratios for a 2nd gen T10:

https://m.roadkillcustoms.com/transm...r-ratio-chart/

If in fact, your friend has a Super T10 with the 2.1 2nd gear, the effective gear ratio with a 3.55 is still only 7.45 vs the 3.08 rear with the car in first gear of 8.13.

A '64 GTO with a 3.23 rear gear and the original M20 with a 2.56 1st gear (mine originally had 3.23 rear gears before I put in the 12 bolt with 3.42's) was 8.27 - very close to the 8.13 with a 3.08 rear and your friends existing transmission.

That 3.23 with an M20 was probably the most common setup from the factory back in the day as it was the standard rear gear when you ordered a wide ratio 4 spd.

Over the nearly 30 years I've owned this car, I've gone from a 3.23 non posi rear until I found a 3.36 posi which ultimately failed, to a 3.42 12 bolt and now am running 3.08's in the same 12 bolt.

[PONTIAC LARRY]

Leave rear alone and maybe invest in a muscle car 5 speed swap with OD later

[leeklm]

Correct on the Super T10- this trans is a 1979 ST10. Btw, thanks for the offer on the test drive- I am up near Rogers , so be sure to look me up if you make it out this way for a car show, etc.

I was hoping to hit the "easy button" on this, but considering the limited options on gears for the 8.2, probably just leave it alone for now, or a swap to 3.36 and maybe taller tires at some point- or as mentioned, look at an OD trans if he tends to keep the car long term.

Thank you for the replies- good discussion!

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[Formulajones]

Originally Posted by PONTIAC LARRY

Leave rear alone and maybe invest in a muscle car 5 speed swap with OD later

This^^^^^

Given the fact that this is a classic car and we all know most people don't drive the darn things more than 2000 miles a year anyway, I'd just leave the 3.55's in it and enjoy it. Not worth the hassle of swapping gears, then living with a subpar 1st gear effective ratio around town, just because he might see the highway once in a while.

Besides, 3.55's just aren't that bad on the highway. Our daily driver for years had 3.55's with a 27" tire and it cruised at 65 all day long at 2900 rpm and got 17 mpg doing it.

Then later, if he really decides to actually drive the car more, longer distances etc.....just put an overdrive in it and be done with it.

[69 Limelight]

FYI, there's a set of used 3.23 , 8.2 gears for sale in the "Performance Parts For Sale/Wanted" section. There's pictures but, I'm no "gear man" and don't know if they look any good or not. No gear experts on this forum have chimed in and given their opinion of quality. As far as thoughts, I'm with Formulajones and one or two others. If only going to drive a few thousand miles a year leave it alone. If you're going to use it as a cross country cruiser go straight for an overdrive. Everything else is just a "bandaid" and with an overdrive you get the best of both worlds. Starting gear multiplication and low RPM cruising. When you drop it in OD it becomes a complete different car. Ask me how I know.

[b-man]

More highway go 3.08, that 2.64 low gear is a game changer. Same 8.13 ratio as the M20 paired with a 3.23.

More city go 3.23.

[PONTIAC LARRY]

Also gear changes of only a quarter rotation are barely even noticeable hence not worth it. 3.23 sucks almost just as bad as 3.55's at 70 mph Thats why I usually recommend 3.08 on automatic folks with 2.56's , to me the minimum of a gear change is a half rotation to b worth it or noticeable regardless

[Formulajones]

Originally Posted by 69 Limelight

I'm with Formulajones and one or two others. If only going to drive a few thousand miles a year leave it alone. If you're going to use it as a cross country cruiser go straight for an overdrive. Everything else is just a "bandaid" and with an overdrive you get the best of both worlds. Starting gear multiplication and low RPM cruising. When you drop it in OD it becomes a complete different car. Ask me how I know.

I've been saying this forever, and people really don't grasp it until they actually perform the swap to the overdrive. Then usually the next comment I hear is "wish I'd have done that sooner" lol

[Tom Vaught]

There were weak GM 3 speed overdrive transmissions (Saginaw) and there were weaker 3 speed GM over drive transmissions (Muncie), and there were STRONG overdrive FORD transmissions. These transmissions were actually the cast iron 4 speed "Top Loader" transmissions but Ford Engineering made the trans with 3 normal gears 1,2, and 3 AND changed 3rd gear to 1 to 1 and 4th gear to overdrive.

If I ever had to have a "highway cruiser" early GM body 64-72 GTO, etc) I would find a Ford 3 speed overdrive trans and bell-housing with the dual pattern (1965) trans mount and run that trans with a Ford clutch plate. Food for thought.

Much stronger than some modern overdrive transmissions.

Tom V.

[punchyponcho]

Hell, you could run a 2.56 or a 2.41 rear with a 3.42 ST10. That’s what I have in my Grand Prix.


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