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Ax-15 transmission-related questions...

Mountaineer1

New Member
Joined
Mar 4, 2024
Messages
13
347 Stroker is in, Blueprint 28oz external balance 415/420 power figures...

What I know - Ax-15 with Dana 20 is the next step. Looking at kits from Toms and Wildhorses.
What I think I know - I need a 28oz 11-inch 164-tooth flywheel with bellhousing and block plate to match for the kits from above. Need confirmation this is accurate.
What I don't know - Which bellhousing (trans bolt pattern) do I need to match up to the above kits? Is any SBF manual block plate compatible?

Additional questions...
What are the experiences that individuals have had with either of the above kits?
Looks like the WH kit has an upgrade to the Centerforce II clutch. Not seeing that option with the Toms kit. Is it even necessary?
Information on the kits is slim online. They both look pretty complete. But I don't know what I don't know.

First time setting up a manual transmission. Very mechanically inclined. All suggestions and info are appreciated.

Thanks

BK
 

jamesroney

Contributor
Bronco Guru
Joined
Sep 11, 2007
Messages
2,596
Loc.
Fremont, CA
347 Stroker is in, Blueprint 28oz external balance 415/420 power figures...

What I know - Ax-15 with Dana 20 is the next step. Looking at kits from Toms and Wildhorses.
What I think I know - I need a 28oz 11-inch 164-tooth flywheel with bellhousing and block plate to match for the kits from above. Need confirmation this is accurate.
What I don't know - Which bellhousing (trans bolt pattern) do I need to match up to the above kits? Is any SBF manual block plate compatible?

Additional questions...
What are the experiences that individuals have had with either of the above kits?
Looks like the WH kit has an upgrade to the Centerforce II clutch. Not seeing that option with the Toms kit. Is it even necessary?
Information on the kits is slim online. They both look pretty complete. But I don't know what I don't know.

First time setting up a manual transmission. Very mechanically inclined. All suggestions and info are appreciated.

Thanks

BK
The correct Bell Housing for the most common AX-15 conversion is the C5TA-6394-A. This bell housing is native to the 66-77 Bronco with the V8. It is a 164 tooth, "small block Ford" engine pattern to "top-loader butterfly" transmission pattern. It is cast iron, and has a threaded boss with a 1/2-13 tapped hole just above the clutch release arm opening on the side for the clutch pivot z-bar bracket. Do NOT be fooled by anyone listing the D1TA-6394-AA bell, which is mistakenly identified as a Bronco bell. It is VERY similar, but the pivot bracket feature is not machined. There are two fundamental versions of the C5TA-6394-A bell. The ones made before mid-68, and the one's after. They appear identical, except for the release arm pivot type. The "early" one uses a wire spring for retention. The later one uses a leaf spring clip. The pivot is riveted to the bell. It IS replaceable, and can be swapped. But it's best to just use the right combination for your Bronco. I prefer the late leaf spring style, but as long as the arm matches the pivot...and the bell says C5TA-6394-A...that's a winner.

You need a flywheel. It is incomprehensible to me that Blueprint can deliver a High Performance 347 engine and not include a matched-balanced flywheel. But here we are. There are three different 28 oz, 164 tooth flywheels, and two different 11 inch ones. In 1968, the 164 tooth flywheel from the "truck" was introduced to the "car." This resulted in a "big flywheel-small clutch" configuration. Beware of that one, and you will be fine. In 1980, the truck flywheel was converted to a diaphragm clutch bolt pattern. Both 11 inch clutches have a 12-3/8 bolt circle, but the long clutch uses 3 groups of 2 (uneven) spacing, and the diaphragm uses even spacing. The aftermarket solved this by providing a "dual-pattern" replacement flywheel. BUT they also resolve it by providing a "dual pattern" clutch. So replacement parts get very confusing. Because things get listed as compatible, and they ARE...but the listings themselves are NOT compatible. (I hope that makes sense...but post a reply if it doesn't come thru...)

So if you want a diaphragm clutch like you claim in your Centerforce reference...then you want EITHER a centerforce clutch / flyweeel combination from a 1981 F100 with a 351W....OR you want the Centerforce retrofit for the 66-77 Bronco. Pick your poison, but pick a combination that works together. Keep that in mind that if you order the parts individually. When you open the Centerforce box, you will find an LUK branded pressure plate, and a 1-1/16 x 10 spline (FORD) input shaft spline. The transmission you selected is an AX-15 built to 1997 Jeep Wrangler 4.0 specifications. The Wrangler 4.0 was built to the Jeep shaft specifications. In 1967, Jeep installed the Buick 225 V6 into the Civilian Jeep, and configured the Borg-Warner T14 3 speed to fit it. The Buick used a GM standard 1-1/8-10 spline clutch hub. Then in 1972 the AMC 258 was configured with the same GM spline. That 1-1/8 spline persisted thru 2006. So the clutch DISC is a GM 11 inch disc. Unfortunately, the Factory never made a Ford 11 inch clutch cover with a GM 1-1/8 disc. So this is where the kit providers come to the rescue. I THINK that Centerforce even has that kit in their catalog now. But Advance Adapters peddles the disc separate.

"Is ANY SBF manual block plate compatible?" NO. Any 164 tooth manual block plate will work. (whether it came out of a car or not) And the truck block plate from a 6 cylinder 300 works too.

Tom's and Wild H have figured all of this out for you. They both did their homework, and made life easy. They both use the same "special parts" from the same sources, and then they package the "common parts" for you. The supply chain and distribution model is VERY robust, meaning it is difficult to bypass the channel and source directly from Advance Adapters. The cost will be similar, if not higher.

The Centerforce 2 clutch disc is a high performance piece, designed to provide additional grip to compensate for crappy factory design. Ford is in-famous for putting crap sized clutches in cars. It started in 1962, and it persists until at least 1995. They FINALLY put a decent sized clutch in a station wagon in the 1967 Bronco. An 11 inch clutch will transmit ~25% more torque than a 10 inch. A CF clutch will transmit ~20% more torque than a factory one. A Dual Friction disc (uses an typical organic surface on the pressure plate sice, and a much higher flywheel eating material on the flywheel side) gets another ~15%. So pick your poison. Your 347 will produce about 400 lb-ft of torque starting at about 3,000 RPM. So you want a clutch that can reliably transmit 400 lb-ft. The CF1 is a very good clutch to get there. But the CF2 is stiffer and more better. It's your money.

Gotta run...
 

Jdgephar

Bronco Guru
Joined
Sep 25, 2012
Messages
1,516
Are you planning to stick with the manual linkage clutch, or change to hydraulic?
 
OP
OP
M

Mountaineer1

New Member
Joined
Mar 4, 2024
Messages
13
Hot damn, a lot to digest. Quick take until I can buckle down....

The plan is definitely kit-derived, as I don't have the time or inclination to one-off all these parts. I assume it's going to be hard for anyone to "tell me which kit is better"; they are both probably more similar than they are different tbh. I am leaning toward the WH kit for the clutch upgrade. I actually came across the C5TA-6394-A while sifting through the crazy amount of info on this forum this morning; confirmation of that is much appreciated. As it pertains to hydraulic clutches (external slave)....If I understand correctly and choose to go that route the C5TA-6394-A is not appropriate? Is this statement correct?

Agree/Understood on the block plate; I should have been clearer.

Block plate - https://www.summitracing.com/parts/sdk-c9dz-7007-a
Flywheel - https://www.summitracing.com/parts/fms-m-6375-k302

Regards
BK
 

Sheehanigans

Contributor
Jr. Member
Joined
Jul 2, 2014
Messages
60
Loc.
Canton GA
I just finished my install, purchased the kit direct from Advance Adapters who makes all the custom parts. The standard clutch was fine for me, maybe you want an upgrade for reasons. I think the only thing I bought separate was the twin stick.

All else was stock 302 manual flywheel and I already had a diaphragm pressure plate. Standard manual bellhousing and the stock clutch linkage feels good. Not a bad install but I succumbed to lot of “while you’re in there” from sheet metal work to a Dana 20 rebuild.
 

steelworker77

Contributor
Full Member
Joined
Feb 29, 2024
Messages
175
Running that exact combo and bought the ax15 kit from wildhorses. Was a pretty straight forward and easy install. Other than the blueprint 347 shitting the bed the trans has been fine. I did opt for the b&m quickshifter and ended up bending it closer to to the driver for an easier reach.
 
OP
OP
M

Mountaineer1

New Member
Joined
Mar 4, 2024
Messages
13
What happened to the blueprint motor? Also I called WH. They had everything. I mean it all. 5 grand later and it’s on a truck somewhere heading my direction.
 

Jakedog

Bronco Guru
Joined
Jan 25, 2010
Messages
1,010
347 Stroker is in, Blueprint 28oz external balance 415/420 power figures...

What I know - Ax-15 with Dana 20 is the next step. Looking at kits from Toms and Wildhorses.
What I think I know - I need a 28oz 11-inch 164-tooth flywheel with bellhousing and block plate to match for the kits from above. Need confirmation this is accurate.
What I don't know - Which bellhousing (trans bolt pattern) do I need to match up to the above kits? Is any SBF manual block plate compatible?

Additional questions...
What are the experiences that individuals have had with either of the above kits?
Looks like the WH kit has an upgrade to the Centerforce II clutch. Not seeing that option with the Toms kit. Is it even necessary?
Information on the kits is slim online. They both look pretty complete. But I don't know what I don't know.

First time setting up a manual transmission. Very mechanically inclined. All suggestions and info are appreciated.

Thanks

BK
I'm looking at the same kits. What transmission is in it right now?

I'm currently running an NP435 with 4:56 gears and 35" tires. It really needs an overdrive if I want to enjoy it on the highway.
 
OP
OP
M

Mountaineer1

New Member
Joined
Mar 4, 2024
Messages
13
I'm looking at the same kits. What transmission is in it right now?

I'm currently running an NP435 with 4:56 gears and 35" tires. It really needs an overdrive if I want to enjoy it on the highway.
No trans in it now. Frame-up build.
 

73azbronco

Contributor
Bronco Guru
Joined
Nov 11, 2007
Messages
8,778
The correct Bell Housing for the most common AX-15 conversion is the C5TA-6394-A. This bell housing is native to the 66-77 Bronco with the V8. It is a 164 tooth, "small block Ford" engine pattern to "top-loader butterfly" transmission pattern. It is cast iron, and has a threaded boss with a 1/2-13 tapped hole just above the clutch release arm opening on the side for the clutch pivot z-bar bracket. Do NOT be fooled by anyone listing the D1TA-6394-AA bell, which is mistakenly identified as a Bronco bell. It is VERY similar, but the pivot bracket feature is not machined. There are two fundamental versions of the C5TA-6394-A bell. The ones made before mid-68, and the one's after. They appear identical, except for the release arm pivot type. The "early" one uses a wire spring for retention. The later one uses a leaf spring clip. The pivot is riveted to the bell. It IS replaceable, and can be swapped. But it's best to just use the right combination for your Bronco. I prefer the late leaf spring style, but as long as the arm matches the pivot...and the bell says C5TA-6394-A...that's a winner.

You need a flywheel. It is incomprehensible to me that Blueprint can deliver a High Performance 347 engine and not include a matched-balanced flywheel. But here we are. There are three different 28 oz, 164 tooth flywheels, and two different 11 inch ones. In 1968, the 164 tooth flywheel from the "truck" was introduced to the "car." This resulted in a "big flywheel-small clutch" configuration. Beware of that one, and you will be fine. In 1980, the truck flywheel was converted to a diaphragm clutch bolt pattern. Both 11 inch clutches have a 12-3/8 bolt circle, but the long clutch uses 3 groups of 2 (uneven) spacing, and the diaphragm uses even spacing. The aftermarket solved this by providing a "dual-pattern" replacement flywheel. BUT they also resolve it by providing a "dual pattern" clutch. So replacement parts get very confusing. Because things get listed as compatible, and they ARE...but the listings themselves are NOT compatible. (I hope that makes sense...but post a reply if it doesn't come thru...)

So if you want a diaphragm clutch like you claim in your Centerforce reference...then you want EITHER a centerforce clutch / flyweeel combination from a 1981 F100 with a 351W....OR you want the Centerforce retrofit for the 66-77 Bronco. Pick your poison, but pick a combination that works together. Keep that in mind that if you order the parts individually. When you open the Centerforce box, you will find an LUK branded pressure plate, and a 1-1/16 x 10 spline (FORD) input shaft spline. The transmission you selected is an AX-15 built to 1997 Jeep Wrangler 4.0 specifications. The Wrangler 4.0 was built to the Jeep shaft specifications. In 1967, Jeep installed the Buick 225 V6 into the Civilian Jeep, and configured the Borg-Warner T14 3 speed to fit it. The Buick used a GM standard 1-1/8-10 spline clutch hub. Then in 1972 the AMC 258 was configured with the same GM spline. That 1-1/8 spline persisted thru 2006. So the clutch DISC is a GM 11 inch disc. Unfortunately, the Factory never made a Ford 11 inch clutch cover with a GM 1-1/8 disc. So this is where the kit providers come to the rescue. I THINK that Centerforce even has that kit in their catalog now. But Advance Adapters peddles the disc separate.

"Is ANY SBF manual block plate compatible?" NO. Any 164 tooth manual block plate will work. (whether it came out of a car or not) And the truck block plate from a 6 cylinder 300 works too.

Tom's and Wild H have figured all of this out for you. They both did their homework, and made life easy. They both use the same "special parts" from the same sources, and then they package the "common parts" for you. The supply chain and distribution model is VERY robust, meaning it is difficult to bypass the channel and source directly from Advance Adapters. The cost will be similar, if not higher.

The Centerforce 2 clutch disc is a high performance piece, designed to provide additional grip to compensate for crappy factory design. Ford is in-famous for putting crap sized clutches in cars. It started in 1962, and it persists until at least 1995. They FINALLY put a decent sized clutch in a station wagon in the 1967 Bronco. An 11 inch clutch will transmit ~25% more torque than a 10 inch. A CF clutch will transmit ~20% more torque than a factory one. A Dual Friction disc (uses an typical organic surface on the pressure plate sice, and a much higher flywheel eating material on the flywheel side) gets another ~15%. So pick your poison. Your 347 will produce about 400 lb-ft of torque starting at about 3,000 RPM. So you want a clutch that can reliably transmit 400 lb-ft. The CF1 is a very good clutch to get there. But the CF2 is stiffer and more better. It's your money.

Gotta run...
excellent writeupp. I used the f150, version flywheel to my 347 because it let me use the f150 mini starter. I have the nv4500 though, then the d20
 

Shimmy

Contributor
1977 Bronco
Joined
Jun 20, 2021
Messages
1,392
Loc.
Maple Valley
i'm starting to gather parts for this swap too. realistically i'm still a couple years out before i do it. going with a hydraulic clutch so i'm using a mid 80s f150 bellhousing.
 

jamesroney

Contributor
Bronco Guru
Joined
Sep 11, 2007
Messages
2,596
Loc.
Fremont, CA
i'm starting to gather parts for this swap too. realistically i'm still a couple years out before i do it. going with a hydraulic clutch so i'm using a mid 80s f150 bellhousing.
Why the fascination with the hydraulic clutch?

AA used to sell an external slave cylinder with their NV4500 swaps and I always wondered why. The mechanical linkage on the Bronco is simple, robust, common, and low cost. So this was always a puzzle for me. I kind of get it when putting a 302 in a Jeep conversion, because there is no factory linkage that works. But it never made sense to me in an EB. Curious about your logic.

There are a number of hot rod conversions that use the internal hydraulic release bearing like the Tilton unit, or the ZF-S42 style, but I always figured that was for people that didn't have any other option.

I am a fan of the clutch cable in 5.0 conversions in passenger cars, but of course you must run a light effort diaphragm clutch and the ever present risk of melting the cable on headers and snapping it. But plenty of Fox cars ran them.

Obviously, if you run an M5OD, or a ZF, you are stuck with the hydraulic. And yes, YJ/TJ/XJ with the AX5/15/3550/NSG370 all use that plastic reverse mounted slave cylinder. But Jeep goes to great pains to route the exhaust and heat to the opposite side of the truck. I'd say that there isn't an exhaust pipe within a foot of the hardware. And they STILL wrap the tube in asbestos.

The advent of fuel injection and electronic ignition has pretty much put a rev limiter on everything, so we don't see nearly as many exploded flywheels these days. I suppose an aluminum bell is "safe enough."

Not throwing shade, just wondering what you see as the benefit.
 

Shimmy

Contributor
1977 Bronco
Joined
Jun 20, 2021
Messages
1,392
Loc.
Maple Valley
Why the fascination with the hydraulic clutch?

AA used to sell an external slave cylinder with their NV4500 swaps and I always wondered why. The mechanical linkage on the Bronco is simple, robust, common, and low cost. So this was always a puzzle for me. I kind of get it when putting a 302 in a Jeep conversion, because there is no factory linkage that works. But it never made sense to me in an EB. Curious about your logic.

Not throwing shade, just wondering what you see as the benefit.

my bronco has some custom made shift linkage in it now and it's currently running a bellhousing from a cougar and small flywheel. the previous owner did this when they swapped the 3 speeds. i want to swap it all out and i figured why not just go hydraulic. i could never seem to get my shift pedal and clutch adjusted to my liking but that could be 💯 due to the make shift setup that i currently have. my understanding is the hydraulic setup will engage and operate much smoother with the need to adjust over time. i've also been looking for an early bronco bellhousing for a some time now and nothing local pops up.
 

jamesroney

Contributor
Bronco Guru
Joined
Sep 11, 2007
Messages
2,596
Loc.
Fremont, CA
my bronco has some custom made shift linkage in it now and it's currently running a bellhousing from a cougar and small flywheel. the previous owner did this when they swapped the 3 speeds. i want to swap it all out and i figured why not just go hydraulic. i could never seem to get my shift pedal and clutch adjusted to my liking but that could be 💯 due to the make shift setup that i currently have. my understanding is the hydraulic setup will engage and operate much smoother with the need to adjust over time. i've also been looking for an early bronco bellhousing for a some time now and nothing local pops up.
OK, here's a warning for you.

There are two fundamental types of slave cylinder. The self adjusting one's and the spring retract ones. The self adjusting ones rely on slight finger pressure on the release bearing, and the bearing coasts all the time. The spring retract pulls the bearing off the fingers, and maintains an air gap and does not rotate except when pressed.

I'm going to call the second type "continuous duty" and the first type "intermittent duty" So you need to be careful. Continuous duty release bearings are designed and lubricated to go the distance. Intermittent duty are usually not sealed, and are not expecting to spin all day, every day.

If you clutch has no need to adjust...it is continuous duty. Cable clutches also do this. Expect to replace the release bearing with every clutch service. The lack of an air gap provides an additional benefit in that there is no real "free-play" to take up. The benefit is that you end up with a little extra usable pedal travel.

There's countless gazillion implementations of both types in the world.
Thanks.
 

jamesroney

Contributor
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Messages
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Fremont, CA
Just great. Here I was thinking an M5ODR2 was what I needed. Apparently, hydraulic clutch and all.
Don't sleep on that M5OD-r2. It was designed with the integrated hydraulic release bearing, so it is designed to run one.

The hydraulic release bearing issue is if you run an intermittent bearing under continuous rotation.

There are two things about the M5OD-R2 that make it ideal for an EB. First, it has an 83mm center distance. Given zero other info about a gearbox, the center distance is the single most important factor in determining strength and durability. The AX-15 is a 75mm trans. The torque capability goes roughly with the square of the center distance. So one with 50% bigger is twice as strong. All other things being equal, the M5OD-r2 will handle about 33% more torque, abuse, load, shock, and any other thing that sounds like "good."

Second, and sort of connect to the first...the M5OD-R2 is overkill for most applications, and they were deployed when the pickups were used as station wagons. So if you find one used, there is a 99% chance that it is in good shape. This is the polar opposite of the NV3550, where if you find one used, they sound like a box of marbles. Or the NV4500, which is a fantastic transmission, but by now most of them have been rode hard, and are very tired.

As long as you can keep oil in it, it can handle the 400HP output from your puny 347. And they almost never break. When they do break, they snap the 1-1/16 input shaft...so it's pretty obvious not to buy that one.

I run the NV4500 and Atlas. It has a 109mm center distance. I've never broke on in my Bronco. (The NP435 is ~100mm center distance.)
 

.94 OR

Contributor
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Jul 5, 2009
Messages
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Nice. Looking forward to a different gear option over my NP435.
Missed out on what appeared to be a clean one for $250 the other day. The hunt continues.
 
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