7Stingray1

Currently I have a 1971 LS5 with a freshly rebuilt 468 with 9.6:1 compression and Hydraulic roller with .560 lift, 227/242 @ 50 on 109* lobe separation. Engine is backed by a th400, 2200 stall, with 308 rear gears out back. Everything in the power train has been tuned, rebuilt or is new.

Unfortunately from the day I finished my year long frame off restoration, I was a bit underwhelmed with the performance of the car. The acceleration has always seemed a bit slow considering the big block.

I am going to make the auto to manual swap. I'm am not going to swap the rear gear because the current diff was rebuilt by van steel and I do quite a bit of highway driving.

This brings me to the m22z Muncie gear set. I already own a m20 and I have the driveshaft, shifter and trans mount to match. The M22Z gear set has a 2.98 first gear which should get me a total 9.17 starting ratio. For second and third gear I have multiple options. 4th is still 1:1

So here are my options:
Option 1
1st: 2.98 2nd: 2.225 3rd:1.59 4th: 1:1
Option 2
1st: 2.98 2nd: 2.225 3rd:1.468 4th: 1:1
Option 3
1st: 2.98 2nd: 2.02 3rd:1.468 4th: 1:1

I am leaning toward option 1 because I want all the gear help I can get. This option keeps the same 25% gear drop between 1-2-3 as the m20 and m21. I know there will be a huge drop between 3-4 but I'm not too concerned about this. I'm more concerned about 1-2-3 being too close.

So my question is has anyone run the M22Z gear sets?

For those who run m20 or m21 transmissions do you ever think 1-2-3 are too close for street use?

All thoughts are welcome. Thanks

carbster09

We must be related somehow! Option 1 is what I am going to have Paul build into a M22Z for me. I just told my local Corvette garage to go ahead. I have a 3:55, but will get it rebuilt into a 3:08. The car will not go into the shop until Nov. So, let me know how you get on. What will you do to swap gears, who will be doing the work? I am just going to order a new built unit from 5speeds.com. The dude is the guru, and I only want to do this once!

Question is; do I need or want that lightwt flywheel?

gkull

TKO 600 gearing:

2.87,1.89,1.28,1.00,.64 Rev 2.56


For those who run m20 or m21 transmissions do you ever think 1-2-3 are too close for street use?

Your 3.08 will spread out the gears, but your 468 should have an abundance of TQ compared to all us poor small block people. I put 100,000 miles on my Vette with a 4.11 and tko600 and I liked how fast I could take off and how close together my gears were.

My Camaro had a m21 You had to slip the clutch to get going, but the closed ratio was nice after that. oh also a 3.08 rear end with a 383 ci

As to flywheel weight. It is the total of the rotating parts. front pulley, damper, crank, fly wheel. Your crank in a 454 is @ 74 pounds. SBC is under 54 pounds. So you can run a 20 pound lighter flywheel and have the same rotating mass (kind of) The flywheel has a larger diameter and hence stores more energy than weight close to the center line. I have only used two fly wheels in my vette 22 pound billet steel 168 tooth SFI and now 168 tooth 11.5 pound aluminum SFI I would recommend a 22 pound for anything with 10 and under effective 1st gear ratios and I would skip over M 4 speeds and there lower TQ rating

roscobbc

I'm in agreement with George. My 489 has 606 ft/lbs torque.It uses 27.2" tall tyres with M21 and 3.08 rear end. I find the ratio's perfect for street use. I would like an overdrive ratio to drop the 70mph cruise of 2500 or so rpm down to 1500/1800 rpm. People will say use a 5 or 5 speed transmission - but non of those have that 'perfect' 1 - 2 - 3 - 4 gear spread that the M21 gives.

7Stingray1

Yes Paul is extremely knowledgeable and has many learning resources available such as his YouTube channel. I plan to purchase the new modular gear set, rebuild kit, and steel mid plate from Paul and use his rebuild book to do the work myself. I have one of the later Muncie cases ( ending in 661? ) which according to Paul, have better metallurgy and are less prone to failure so I will be sticking with my existing case and tail housing. I am currently getting my car ready to go into primer, so unless things go REALLY well, you will probably have your M22Z installed before I will.

7Stingray1

Well it is good to hear that the ~25% gear drop between 1-2-3 will not be too bad, that's really what I was hoping for. I know the 3.08 rear gear can stretch trans gears out for a loooong time. With the th400 I would only shift once and hit 90+ mph!!!

I've looked at the overdrive trans on the market right now but all of them have this huge drop between 1-2 which would work well with with a low rear gear but my 3.08 would really stretch that 1-2 drop out. The tko 600 has one of the closer 1-2 drops.

With the TKO 600 and 3.08 rear the equivalent gear ratios are 10.07, 6.06, 4.13, 3.08, 2.09

With M22Z option 1 and my 3.08 rear the equivilant ratios are 9.17, 6.85, 4.91, 3.08

So with the tko 600 I get better 1st performance but as soon as I shift to second I'm suffering from the 3.08 gear again and M22Z become more favorable for 2-3.

Just No perfect solution! (With a 3.08 rear gear of course)

68vette2go

I have been suffering from a similar challenge. I recently built a new big block chevy 427 for my vette. Bulletproof bottom end, with big valve alumni square port heads, 10.7:1 compression and a 6.30 lift roller cam. About 600 hp on the dyno. I have 3:08 gears and an M21 close ratio 4 speed. With the M21's 2:20 1st gear, I have an effective 6.77 gear off the line. Since the motor does not wake up until about 3,000 rpm, this is a terrible combination. After 3 months of searching I finally bought a Doug Nash 4+1 5 speed transmission. This gives me a 3:29 1st gear and a close ratios up to 1:1 in 5th. I will have an effective 10.15 off the line which is like having 4:56 gears and the m21. Transmission will be installed this week, so hoping for a great outcome.

raylag64

I sent Paul an email yesterday, and he replied that he does not sell the gears. I'd really like to do this conversion. where else might I find the kit to convert my M20 to a 3 speed w/overdrive?

69ttop502

I went with the perfect solution lol! A Richmond 5 speed with the 1:1 5th gear. A lot to like in that in cruise you are operating in its strongest and most efficient mode. Should still cruise at 70 around 2500 rpm. Your 3.08 gears are what it was made for. I had Paul go through it to make sure it shifted well. You can find them for sale, but I hear parts are getting scarce. I am going to be pushing a little more than 650 horsepower through it so I hope it lasts.

cv67

havent seen a richmond or DN in ages! Op regardless of what you choose youll love the manual it will feel faster just swapping period.

used to be when 55 mph spd limits were around a 4 spd was all you needed, today 70 is a slowpoke. Post up on what you decide