fmx to 4 speed swap

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Joined
Dec 21, 2013
Messages
356
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Location
Brier, Washington
My Car
1972 Fastback (Factory sprint, but now a bright red Mach 1)
351c 2v(big ol cam, holley dominator intake, roller set, edelbrock 4bbl)

fmx
Hi all

I have had read for years how bullet proof the fmx was supposed to be....not my experience. Blew up my second one a couple weeks ago..no third, slipping second..it's a mess. Went out to the shop yesterday a quart of fluid leaking out from under the trans... That, is the end of my interest in the auto box. I've been collecting parts for a top loader swap for a few months, made some good deals and trades and I think I have most of what I need. I want to start this yesterday!

I have heard the c4 crossmember is the same as the 3/4 speed crossmember. Any body confirm? Also need a c4 yoke. I have been told they work for top loader.

Anyone here done this swap? Any tips? Anyone have a yoke or crossmember to sell?

Thanks Kole

 
I don't know any answers to this but I would be interested in doing the same swap on mine as well FMX to 4 spd. Please post your progress and any issues you run into.

 
I don't know any answers to this but I would be interested in doing the same swap on mine as well FMX to 4 spd. Please post your progress and any issues you run into.
I was thinking maybe I would do a step by step pic album. I couldn't find one here with the search function. Should be fun at least for the laughs.

 
The crossmember should be easy to source. The yoke can be purchased new if necessary. The clutch pedal parts and z-bar linkage are usually the most difficult items to track down. I converted my car years ago from a C-6 to a toploader. Off the top of my head some of the items you need are:

Flywheel

Flywheel bolts

Clutch kit

pressure plate bolts

Clutch fork

Engine block plate shim

manual trans starter

bellhousing

transmission

bolts for transmission to bellhousing

shifter

speedometer cable

yoke

driveshaft

u-joints

crossmember

clutch and brake pedals

rubber pads for pedals

under dash spring for clutch pedal

rod from clutch pedal to z-bar

Engine bracket pivot for z-bar

Body pivot for z-bar

bushings, retainer clips and felt washers for z-bar

Adjustable rod from z-bar to clutch fork

2x springs for z-bar rods(anti rattle)

Firewall gasket for rod from pedal to z-bar

Wiring and switch for back-up lights

Wiring jumper for neutral safety switch

various bushings for linkage rods and springs

 
I too have a leaking fmx that I would like to convert. Please keep us updated.

 
I have heard the c4 crossmember is the same as the 3/4 speed crossmember. Any body confirm? Also need a c4 yoke. I have been told they work for top loader.

Hi,

I'm fairly sure that the FMX yoke is the one to fit for a Toploader. Been a lot of years since I've done such a conversion, just try your FMX one into your Toploader to see if it fits. As has been said you can purchase them new anyway.
 
Thanks Mike, I was thinking I would use the ring gear bolts I have. But now that you mention it.. I bet they are wrong. Also didn't think about the starter, and that steel plate that goes between the bellhousing and block. I can't find the crossmember yet. Everyone says they are common...no one has one:chin: I have also read the drive line will work from an fmx.

one

I have...

Flywheel

Clutch

Pressure plate

Bell housing with fork

Throw out bearing

Pilot bushing

Wide ratio top loader

Hurst shifter

Z bar

Pedal assembly

Need both clutch rods, crossmember, yoke, bolts for flywheel, starter,....if I at least had a crossmember I would dive in.[/size]


4VFOUREVER,

I tried the fmx yoke.....no way will it work. must be the c4

ZAX..

I've been watching Craig's list and eBay constantly for 7-8 months. You get an idea of what people want for the parts. Then every once in a while someone actually wants to sell one, and they list it for half what everyone else does.

I paid 500. For a clean top loader. 150 for the pedals, 60 for the z bar with pivots, 80 for bell housing, flywheel,pressure plate . Shifter came with trans.

I'm not saying it will be cheap. But I don't thing it has to be three grand either....ha! Easy for me to say now!

 
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I believe the FMX yoke is the same as the C-6 yoke which are both too big being 31 spline units. The smaller 28 spline yoke is what you need.

 
I believe the FMX yoke is the same as the C-6 yoke which are both too big being 31 spline units. The smaller 28 spline yoke is what you need.
Thanks, Pat is hooking me up with a yoke and crossmember! Anyone have an opinion on the value of the block plate? ....dust plate......bell housing plate...whatever it's called? Do I need it?

 
I believe the FMX yoke is the same as the C-6 yoke which are both too big being 31 spline units. The smaller 28 spline yoke is what you need.
Thanks, Pat is hooking me up with a yoke and crossmember! Anyone have an opinion on the value of the block plate? ....dust plate......bell housing plate...whatever it's called? Do I need it?
I am doing the same conversion to mine. FMX to 4-speed. The block plate that you are asking about needs to be there, but is no different from automatic to 4-speed. I don't even think they vary by transmission. I mean a small block bell housing attaches the same as a small block tranny. The 351C has the small block pattern.(Same as 289/302/351W.) I was told for years from various people that the 351C did NOT have the small block bell housing, but it works on mine.

Now having said that, mine is still disassembled and not in the car, but I have multiple copies of most all the parts.

 
Just my 2c.

For all the effort you are going to go through, have you considered a box with overdrive?

I went from fmx to aod and love the OD.

I seriously considered a toploader but I still would be revving too hard on a highway cruise.

If you go manual, try 5 or 6 speed.

 
The automatic block plates have the access cover at the bottom to get to the torque converter bolts. The manual transmission plates have no access cover. It also matters which flywheel tooth count(164 vs 157) you end up using to which block plate will correctly locate the starter.

 
I believe the FMX yoke is the same as the C-6 yoke which are both too big being 31 spline units. The smaller 28 spline yoke is what you need.
Thanks, Pat is hooking me up with a yoke and crossmember! Anyone have an opinion on the value of the block plate? ....dust plate......bell housing plate...whatever it's called? Do I need it?
I am doing the same conversion to mine. FMX to 4-speed. The block plate that you are asking about needs to be there, but is no different from automatic to 4-speed. I don't even think they vary by transmission. I mean a small block bell housing attaches the same as a small block tranny. The 351C has the small block pattern.(Same as 289/302/351W.) I was told for years from various people that the 351C did NOT have the small block bell housing, but it works on mine.

Now having said that, mine is still disassembled and not in the car, but I have multiple copies of most all the parts.
It's a little weird, but I'm thinking there are two small block bellhousings. One for the 164 tooth flywheel, and one for the 157 tooth. I have looked on eBay for these plates and there are two types for sale. I think the reason some people think the Cleveland is a big block is because of its 400m cousin truck motor is a big block.

Have you started your swap yet?



Just my 2c.

For all the effort you are going to go through, have you considered a box with overdrive?

I went from fmx to aod and love the OD.

I seriously considered a toploader but I still would be revving too hard on a highway cruise.

If you go manual, try 5 or 6 speed.
Yes, thought about it.... Especially the 5 speed.. but, came across a good deal on toploader and all....too late now, I'm ready to start. I'm really just building a street cruiser anyway...thing gets about 8-9 to the gallon!



The automatic block plates have the access cover at the bottom to get to the torque converter bolts. The manual transmission plates have no access cover. It also matters which flywheel tooth count(164 vs 157) you end up using to which block plate will correctly locate the starter.
I'm going with a 164.so I can use an 11 inch clutch. My bell housing is a dize. So I'm pretty sure I can use the bigger flywheel.

 
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Well, it's go time..

Car way up on stands, dropped the drive line, headers, starter, linkage, cooling lines, Speedo, crossmember, unbolted the TC, and dropped that big choady monster on the floor. Yea, and mopped up at least a quart of that Damn sticky red stuff.

So! On the fun stuff. Went after the pedals first. That was a sixty eight cuss word job. Not meant to come out. It will.... But not happily. Got to drop the steering column on the floor.. take out the front seat, you'll be laying on your back for a while longer than you expect. Take out the four bolts holding the column, then the four through the firewall/ brake booster.

Take off the brake pedal from the plunger, then pull pull the through bolt pivot for the pedal. It ain't comin out with that on there. ( ask me how I know.

Now...for the really bitchy... You have to remove the tinwork that holds the main green fuse block, just to the drivers right of the column... The assy. Ain't comin out with that on there...ask me how I know...two 3/8 bolts..no biggie if your hands are the size of an eight year old...well maybe even then.. pulled the radio, to get one, the other is a 1/4 inch ratchet job one little ticky at a time..go to your happy place...hum a little song.... Ok, now weasel that thing out.


So some one suggested you could use the old auto pedal bracket. No way, the clutch pedal bushings are factory swaged in. So I polished up all the journals on the brake and clutch pedals with some 600 grit, and put the to better for a good polish. Coated all the journals with some litho white, and a little for each plastic bushing. Did a test fit up on the bench.

So I thought, don't want those pedals mounted til I get the bracket back in over the steering column and back in place with a bolt or two. So...back in ...thats another six dozen FU! But hey it's ok we are making progress. Head crammed in the foot well, column on my belly, flashlight in my teeth rusty chunks of some kinda crap in my eye. got the nuts on loose, now for the fuse block tin. Yep that was still fun. . So all going good... Well.....not quite as good as I was thinkin. The brake goes in fine, but the clutch pedal won't clear the heat duct to slide the 4 inch shaft sideways.... So un bolt the heat duct, whater they seal it with in 1972 is crumbly crap to blink out of your eyes. Ok, so now... No, it still won't go in, the duct mounting stud is in the way, bend it with the vice grip tap in the clutch pedal.. looks good now to get that spring in there.....

Yea, that spring....it don't wanna, and you can't even see where it's supposed to seat. Into the vice and welding rod wrapped through to hold the spring collapsed. And shot it off the cabinet, and shot it off the car, @#$#&%+@#! That was ridiculous!

That spring took an hour and a half and a year off my life. Moral of story! Whatever you do, mount the clutch pedal on the bench!!!

Tomorrow the z bar... That should be easy!

 
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Well day two...

Mounted the frame side pivot ball, with a couple bolts, mounted the bell housing temporarily so I could also mount the bell housing side pivot.

So got the z bar loaded with the bushings ...and slid it in to check the header clearance. Clank! Now

why would a performance piece like exhaust

headers not be built with a manual trans in mind??!!

It was cool down there, I just lay there and stared at it. Well if I used a 3 inch push rod....maybe... Nope.

If only the number 8 tube were 3 inches further forward..there is room.. would the to move the number 5 too.. or spend five hundie on a new set...


So I'm cutting up headers, nothing to lose I guess, they aren't going to work the way they are, I'll post pics if I'm successful.... Or pics of new headers if I eff it all [



 
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The no room at the header sitch
t70c4o.jpg


Headers before
27zj8du.jpg



Chopped thinking
avha88.jpg


This should work.
xarxvn.jpg



 
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Well... I think it's going to work! ...at least as long as my amateur welding holds up. Did some grinding to pretty up all that boogerwelding...I used an 18" piece of exhaust pipe I got at perilous, for about 12$ . I cut it up with a sawzall, and then did some grinding and fitting. I don't think I lengened any of the tubes, as I added about as much new tube as I cut out. Time to start turning bolts starting with the block plate. I'll take stage by stage pics going forward

.
spxirp.jpg


 
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For the money and challenges of a four speed, you may as well go to a five or six speed. For the linkage, I would consider changing to a hydraulic clutch with a hydraulic release bearing. That eliminates all of the linkage and header clearance issues. It would be easier to round up the parts needed too.

 
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