After several years of trying I finally got enough money together to get the M23 that I've been wanting to put in my '69 Camaro. I'm planning on taking the car to Beech Bend Raceway this July and doing a little drag racing, and I was afraid that the old M20 wouldn't hold up. I called AutoGear several times and worked out the details on gear ratios, shaft size and other options. I think I have a transmission that will handle the 427 that I have now and will probably be good enough for the 540 that I have planned for the future.
I thought that I would do a thread on the assembly of the transmission since there are no instructions that come with it. From what I understand I'm the first individual that has ordered one that wasn't assembled. I had to make a call to AutoGear and ask a few questions about some parts that I wasn't sure about. There are extra parts that come in the small parts kits that will not be used, and this can be a little confusing. There are several differences between this transmission and a standard Muncie transmission. If you are familiar with the Muncie then you will notice the differences as I go along. I didn't have a Muncie that was disassembled, so I couldn't take pictures of these differences.
Start by unboxing everything and inspecting all of the parts. I found some of the polishing media stuck between some of the teeth on some gears. This could cause some big problems if not removed. Then wash all of the parts in clean mineral spirits or other cleaning fluid.
Yeah, that's a great write-up! I haven't rebuilt a 4-speed in over 40 years, but I don't remember ever needing a press. Is that something new with this "improved" Muncie?
Not exactly.
Plenty of guys built 4speeds with a block of wood and a hammer. In theory you could do the same here; although, in that case I'd have you use a traditional Muncie-style mainshaft, and synchro hubs.
The setup Fred has, has a half degree of helix to the splines for the hub; they get REALLY tight as you press them on.
We tend to run tighter fits than a factory box, but using an old gear or a piece of pipe with a lot of tapping would work...just make sure you keep things square.
The speedo gear can be heated in a toaster oven and slid on. Just mock up the tailhousing, mark the shaft through the speedo hole and slide on. Any adjusting can be done with a piece of pipe slid over the end of the mainshaft.
We traditionally assemble the 'modular' cluster gear for the customer; due to the large size of the snaprings and the pliers we use are a racheting type (for safety). You can do them with standard snapring pliers, but you better have strong hands and keep your noggin out of the line of fire, should your hand slip.
One thing that I forgot to mention is that this new 32 spline transmission is 7/8 inch longer than my old 27 spline M20. I'm getting a new drive shaft anyway, so it's no big deal to me. If you are thinking of replacing your 27 spline Muncie with one of these then this is something that you need to keep in mind. I've also been told that my shifter position might change slightly, so keep this in mind too.
The 32-spline transmissions (ST-10/Muncie) are ~0.750" longer than the 27-spline counterparts. When going from a STOCK gearbox to a SuperCase-equipped gearbox; you have to add 0.150".
27-spline Muncie to 32-spline S'Case will be 0.150 + 0.750; or 0.900 total.
It should fit on a factory crossmember without moving it; but as Freddie says your driveshaft and shifter will need a look-see
Question for Big Gear Head and AutoGear....any thoughts on using a ClutchTamer to keep that twin disc clutch from shocking the driveline too hard??.
I've seen some pretty impressive results testimonials about the idea, and it makes a ton of sense when you review it......I just know I broke a bunch of clutch discs, U-joints, driveshafts, and even a rear housing using the old school idea of a total grip clutch.
I like the idea a lot. Does it work? The testimonials imply that it does. I'd guess you need a customer who understands the value of small adjustments, notes and patience to dial in their application.
I DID have a customer with a 55 chevy series 1 gasser-style truck that got the adjustment on his 'soft-lok' style clutch WAY wrong (he listened to an 'expert' who wasn't as familiar as he sounded) and he wrecked the gearbox, the driveshaft, and the Dana 60 AT THE SAME TIME...in 2 passes or less LOL.
What I learned from this was drive-line shock mitigation is key. one end of the system has to act as a buffer; either the tires slip or the clutch does. I used to recommend Tim Hyatt to all my customers that needed a 'slipper clutch', but he's since passed away. Customer with the truck got the clutch ironed out thanks to Tim, and was knocking down 1.50 60' times with a tunnel rammed SBC.
My fastest customer is capable of turning a 9.9x using a box similar to Freddie's (that one is fully slickshifted, but uses the rings as a friction brake; and an inline shifter in a flyweight 60's nova with an older ProStock type chassis and fiberglass body panels)
Im VERY interested in a Clutch Tamer application.
As it sits, we went with a 2.56 1st gear for Freddie to make up for the he-man meats on the back of his car. He should be good for well over 600ft lb and it should easily shift at 8krpm
I really don't know how this clutch is going to act. It doesn't have any springs in the hub, and I've never used a clutch with no springs. Also, this is a dual disc and it has the ceramic pucks, so I'm wondering how hard it's going to hit. Jody didn't say anything about it being too aggressive for street use, and McLeod sells it as a street clutch, so I'll give it a try. I don't know anything about the clutch tamer.
People that sell clutches always set you up with more clutch capacity than you really need. It's not the best thing for your car overall, but chances are you won't blame them if something else breaks.
According to Mcleod, the RXT Street Twin has 1000hp capacity, likely holds over 1000ft/lbs of torque. It will work just fine for street driving, having a lite pedal and smooth engagement, but sidestepping that clutch with traction may hurt even an M23.
The torque output of the engine isn't a meaningful number as far as determining how much torque the transmission's input shaft will see in a drag race setting. An engine might have a 650ft/lb torque peak, but if your clutch has 1000ft/lb capacity, the result of you sidestepping the clutch is going to be 1000ft/lbs being passed along to your transmission's input shaft. That's because even though the engine only makes a maximum of 650ft/lbs of torque by itself, installing a clutch with 1000ft/lbs of capacity behind it makes it possible for the clutch to borrow an additional 350ft/lbs of inertia energy from the rotating assy. Hitting the input shaft with an additional 350ft/lbs might sound like a good thing to get the car moving, but that borrowed inertia energy must then be paid back so the car doesn't actually gain anything from the extra hard hit.
Ideally, your clutch's ultimate capacity should be as closely matched to your engine's peak torque output as practically possible. Having a minimal amount of excess clutch capacity will minimize the hit on your transmission's input shaft, it will also minimize the amount of bog that you will see.
When you have a lot of excess clutch capacity and plan on drag racing, it really helps to use some sort of buffer. The buffer basically just temporarily reduces the capacity of the clutch, allowing it to slip a bit to minimize or eliminate any added inertia hit. Mcleod actually makes a device that does just that, but it only works with hydraulic releases. Magnus makes a version that adds a line-loc solenoid to the mix, but it too only works with hydraulic setups. My version works with hydraulic, cable, or linkage style setups. I continually tweak the website in an effort to make the concept easier to understand, if you haven't been there in a while it might be worth another look.
I tell my customers if they decide try the ClutchTamer and for any reason it does not work out for them, i'll buy it back. So far, no one has taken me up on the offer.
Does this thing bolt into a '69 Camaro or does it require fabrication of brackets and other parts? I don't want to add any holes to my dash, so will it fit behind the dash?
Ok, I had time to read most of the page on this clutch tamer and I'm sold. I think this would work well with the dual disc clutch. I'm a little concerned about the tires breaking loose at the 2nd gear shift, so this might take care of that problem. I'm running 31/18.5/15 Hoosier radials and I've never had the car on a drag strip with these tires. So how hard is it going to be to install this on a '69 Camaro with all of the factory clutch linkage? I don't want any new holes in the dash, so it has to fit completely behind the dash. I see several kits for the Mustangs, but nothing for any GM cars. I know that the Mustang guys like the manual transmissions and most of the GM guys have gone soft and went to automatics, but I like shifting gears with a clutch. As long as my left leg and right arm still work that's the way it's going to be for me.
Just going off of memory and knowing the fact that your '69 Camaro takes the same steering column and the same pedal assembly as my '72 Nova....I can visualize you'll have to make some kind of bracket to bolt to probably the same bolts that hold the column up to the dash, then it should be simple to figure out where the attachment point on the clutch pedal would be.
The bracket under the column would hold the adjustment end of the ClutchTamer cylinder right below the small trim piece that covers the bottom of the dash opening for the column. Or it could mount a slight bit higher in place of that small trim piece, and you just save that trim piece for the future.
I measured the distance from the front of the M20 to the front of the shifter and then mounted the shifter on the M23 and measured again. It moved the shifter back about 1/4 inch. Not bad. I think it will still fit in the hole in the floor without more modifications. It didn't move the shifter to the left a noticeable amount. I'm going to make a new aluminum transmission mount with the holes offset 3/8 inch to the front so that I don't have to slot the holes in my cross member.
I'M REALLY DIGGIN THIS!
I was a little nervous when you went to the 32-spline output because you'd put so much time and effort into your interior. Even though it SHOULD be fine, you just never know 100% until you get everything together.
As TV's Hannibal Smith from The A-Team said: "I love it when a plan comes together!"
Made a new transmission mount with the holes offset 1/4 inch to make up for the slightly longer transmission. This way I don't have to slot any holes in the cross member.
Yes, solid. I also have solid mounts on the engine. I've been running solid mounts for as long as I've had this car. (1984) Never run a solid mount on the transmission unless the engine is also solid mounted. I also have solid mounts between the body and frame.
Nice transmission you have and good build instructions
Have you seen this video from Paul Cangialosi about the differences in 27 and 32 spline extension housings and Hurst shifter mounts to -69 Camaro?
Tell us more about your 427, i have a 427 BB and one of Nathan`s M22W gearbox but no car to put them on
Thanks for posting the video. I actually made a bracket similar to that a few years ago for a ST10 that I put in a '69 Camaro. I wish I had the prints for the bolt pattern when I did that one. I had to do it the hard way by measuring everything as best as I could.
As for my 427, I used one of the original 107 bow tie blocks with a steel GM crank, LS6 rods, TRW pistons, 3rd design GM 077 aluminum heads, Holley strip dominator intake, 850 Holley, modified HEI distributor, Comp Cams hydraulic cam, aluminum rockers, titanium retainers... I'm in the process of changing the pistons, rods and cam. I'm going to raise the compression ratio and I'm putting my old Comp Cams 11-604-5 solid cam back in it. Probably going to use Manley rods and Diamond pistons.
I've already had this cam in it before. I got lazy and though I wanted a hydraulic cam, so I gave that a try. Now I want my solid lifters back, so I'm putting this one back in it. I've had this cam for years. I didn't go too wild with it because at that time this was strictly a street car, and still is for the most part. I numbered the lifters when I took it out so it will go back in the way it was before.
I'm going to break it in on the Sta-Lube and then put in Brad Penn 80W90. Nathan said that the Sta-Lube was not consistent as far as performance.
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