[gman005]

I am running a 225/70/15 tire which is 27.4 inches tall.

[TB1]

Originally Posted by jhein

I started taking a closer look at the gearing for the TKX and I don't think it will help me very much with my current 3.31 gear. Seems like the goal should be lower gearing in 1-3 then a good OD ratio. The close ratio gives me a little better 1st, same in 2nd, worse in 3rd and the OD puts me at 2.25 or 2.68. The wide ratio is better in 1st and 2nd, worse in 3rd with OD at 2.38. They recommend a 3.73 rear gear and I can see why. I'm not really interested in changing my rear gear (again...). Seems like the M22Z would be a better choice if I keep the 3.31 gear. I know it's not as strong as the TKX and I give up the OD, but I'm a backroad cruiser with a 3.31 so I don't think I'll miss the OD, and I'd have a nice improvement in 1st and 2nd gear.

TKX:

Wide Ratio – 3.27, 1.98, 1.34, 1.00, 0.72
Close Ratio – 2.87, 1.89, 1.28, 1.00, 0.68 OR 0.81

M22Z:

2.98, 2 .04, 1.46, 1

M20:

2.52, 1.88, 1.46, 1

I'm running the .68 OD ratio with 3.23 gears and a 25.7" tall tire with a pretty mild 410-420 hp 500+ ft lbs 455 and it is a really nice combo gets out of the hole pretty good and cruising the highway at 70MPh is right around 2000 rpm and with the cam installed about perfect. Had I known I was heading in the TKX direction I would have most likely gone 3.73 when I had the rear end rebuilt.

[tom s]

Pretty much like TB1,3.31 in the back and 3.27 first and .68 OD.Tom

[soupman]

I run a 3:27 rear with 26.5 tire and runs exactly 2100 at 70mph. Just did a 7 hour round trip on I90 with cruise on and watched the gauges all the time.

[jhein]

I appreciate all the replies and input. But, just to be clear, I'm not considering the swap because I want the OD. I think that's probably why most people want a 5 spd. I'm fine with a 3.31 final drive ratio for my driving. What I want is a stronger unit with better bottom end. From talking to various vendors, it seems the gearing for TKX was chosen to work best with a 3.73 rear. That's what they all have recommended. I think the M23Z is looking like my best option.

[64speed]

Originally Posted by jhein

I appreciate all the replies and input. But, just to be clear, I'm not considering the swap because I want the OD. I think that's probably why most people want a 5 spd. I'm fine with a 3.31 final drive ratio for my driving. What I want is a stronger unit with better bottom end. From talking to various vendors, it seems the gearing for TKX was chosen to work best with a 3.73 rear. That's what they all have recommended. I think the M23Z is looking like my best option.

Then you do not want an M23Z. If strength is all you’re concerned about.

[tom s]

Richmond 5 speed,3.27 first and 1-1 5th

[Don 79 TA]

IF strength is a concern and you have some funds look at Roletk/Jericho/Liberty/JHT
Roltek makes some really good stuff
i want to convert back to a 4spd and if i do i'd like a Roltek
i don't really have the need for the 5spd and the TKO 3550 i have is from 97
it's held up fine, but i don't beat the snot out of it with the current engine setup
i do love that first gear though

[jhein]

So I talked with Jody at Jody's transmission and Jeff at Midwest Muncie. They both say that the M23Z will handle the 550 tq motor fine. Jeff said it's good to 800 hp? Jody mentioned one notable failure that was discussed here but said that's the only one he's aware of and he runs the M23Z in his BBC Chevelle and he loves it. He did say that he prefers the TKX due to better shifting. Jody also said that he has the TKX in stock with the .81 OD and 2.87 1st gear. That's much more reasonable for my 3.31 rear and that would give me the equivalent of a 3.77 rear with my current M20 in 1st.

So overall, I have come around to agree with most everyone here that the TKX with the 2.87 1st and .81 OD is the best choice. So there ya go.

[66beaumont]

Originally Posted by jhein

So I talked with Jody at Jody's transmission and Jeff at Midwest Muncie. They both say that the M23Z will handle the 550 tq motor fine. Jeff said it's good to 800 hp? Jody mentioned one notable failure that was discussed here but said that's the only one he's aware of and he runs the M23Z in his BBC Chevelle and he loves it. He did say that he prefers the TKX due to better shifting. Jody also said that he has the TKX in stock with the .81 OD and 2.87 1st gear. That's much more reasonable for my 3.31 rear and that would give me the equivalent of a 3.77 rear with my current M20 in 1st.

So overall, I have come around to agree with most everyone here that the TKX with the 2.87 1st and .81 OD is the best choice. So there ya go.

I have close ratio with .68 od and 3:55 gears and 225/70r14. Under 2000 rpm cruise and will climb any hill in the mountain passes in od no problem and great launch. Love this trans and shifting is awesome. Far superior to my tko

[tom s]

X2 on the .68 OD.Tom

[jhein]

Originally Posted by 66beaumont

I have close ratio with .68 od and 3:55 gears and 225/70r14. Under 2000 rpm cruise and will climb any hill in the mountain passes in od no problem and great launch. Love this trans and shifting is awesome. Far superior to my tko

You have a lower gear and smaller tire so with your setup you would be at 2300 rpm at 75 mph. I will be at 2500 at 75 mph. If I did the .68 OD then I would be at 2100 rpm. I don't know but think your motor may be happier at that RPM than mine will be. Also, I rarely cruise above 65 where I'll be at 2170 rpm in OD.

[Gator67]

I bought a T-56 magnum (and BH, clutch, etc.) for my 70 Formula from Bowler several years ago. I just got around to installing it and was very pleased by how responsive they were to emails and calls when I had questions. I'm now considering a TKX for my '67...would like to use Bowler again, but will shop some

[jhein]

I'm getting everything from Jody's Transmission. I've been sucked into the vortex. I'm going overkill on almost everything. QT bellhousing, Holley crossmember, new driveshaft, flywheel, clutch kit, Qwik Stik shifter, etc. Expensive but it will all be there so no excuses. Now my new weak link will be the 12 bolt, I guess.

[Gator67]

Originally Posted by jhein

I'm getting everything from Jody's Transmission. I've been sucked into the vortex. I'm going overkill on almost everything. QT bellhousing, Holley crossmember, new driveshaft, flywheel, clutch kit, Qwik Stik shifter, etc. Expensive but it will all be there so no excuses. Now my new weak link will be the 12 bolt, I guess.

I had to shave the bottom lip off my QT bellhousing...extended below the oil pan and I felt it was a disaster waiting to happen.

[jhein]

Originally Posted by Gator67

I had to shave the bottom lip off my QT bellhousing...extended below the oil pan and I felt it was a disaster waiting to happen.

Thanks for that. I'll be sure to mention it to my guy.