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3 Speed Auto FMX to 5 Speed Manual

8572 Views 10 Replies 2 Participants Last post by  70Mach1
Hello, I have a 1970 Mustang Mach 1 with a 351 Cleveland 2V, and a 3 speed auto FMX, and I have been wanting to do the swap to a manual, but im not sure how to go about it. Which bellhousing do I use, and which transmission? The engine is basically stock, its been bored 30 over, and I have a set of flows on it, So im pretty sure it cant be making over 300 horse... I really wanted to do a 5 speed, or a 6 speed. Also, where would I find the clutch pedal, the linkage, ect... Or I was also considering a 5 speed automatic if the manual conversion was to expensive... Any feedback would be appreciated! Thank You so much for your time! Anthony
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G'Day 70Mach1..........welcome to Ford Forums.

I swapped my FMX out for a toploader originally and then slapped in a 5 speed Tremec TKO.

First off, what country are you in? If you're in the US, then lucky, because it's going to be a whole lot cheaper :hy:

Most of the parts you can pick up from a wreckers, or in the US, they'd be plenty of aftermarket new cheap parts.

What you'll need:
Gearbox & Shifter
Pedal box as mentioned (you may get away with just fitting a manual shaft in the box and add a clutch pedal....saves removing the whole box)
Manual Flywheel
Clutch (pressure plate & disc)
Clutch Fork
Clutch line (hydraulic with slave/master cylinders and tube or cable type setup)
Starter Motor spacer (auto flex plate teeth at different depth when mounted)
Sandwhich Plate for a manual (metal sheet between gearbox & block)
Speedo cog to fit new gearbox on your sender
Slip Yoke for gearbox output shaft (our FMX one may fit depending on box type)
New front uni for driveshaft (maybe)
Possible driveshaft lengthening/shortening depending on final fit
Spiggot Bearing for back of crank (where gearbox input shaft sits)
Throwout Bearing (goes on clutch fork to release clutch)

With a TKO conversion, I'd say AU$5000-$5500 doing it yourself (not counting driveshaft work if needed).

With a Toploader it's a whole lot cheaper and easier, about AU$2000.

In the US a TKO will cost US$1300-$1700. In Australia, they're about AU$3500-4000!

You could sell your auto stuff afterwards to offset a little of the cost.
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Thank you, Im in the US, but what TKO would you suggest? the Tremec 3550 or perhaps the tremmec tko 500? and also which exact bellhousing to use?and how would I go about finding the clutch pedals and linkage? Thank you so much! I greatly appreciate your knowlege on this! -Anthony
70Mach1 said:
Thank you, Im in the US, but what TKO would you suggest? the Tremec 3550 or perhaps the tremmec tko 500? and also which exact bellhousing to use?and how would I go about finding the clutch pedals and linkage? Thank you so much! I greatly appreciate your knowlege on this! -Anthony
OK, your in the US, so your back pocket just thanked you a lot!!

The TR-3550 was the very original "Tremec" which evolved into the TKO, which has now been replaced by the TKO 500 & 600. The TR-3550 are still available, but the TKO's really don't cost that much more and are by far a much stronger gearbox......just incase you decided to build a stronger motor down the track. I'd go the TKO-600....although I like to drag race etc, so its good insurance to go strong, and it saves upgrading later. I'm not sure of the prices in the US, but I'll give you a few good places to call.

Here's a few links.

Tremec Website. Check out the different TKO's. They come with 0.82 and 0.68 5th gears....I'd recommend the 0.68 for highway economy, the 0.82 is for circuit racing so the revs don't drop so much.

Here's a few links to Ford Tremec suppliers who would definitely have all the information, if not the parts also, for your conversion. From all the searching I've ever done, these are the best 2. They have everything from bellhousings to yokes.

As for buying the the gearbox, I bought mine from these guys below 4 years ago (older style TKO) for US$1300 (including shifter & yoke) and free shipping! They were the cheapest in the US.....and I did some searching :hy: Would be interesting to see what TKO 500/600 price they give you compared to the other links.

Ahh, looks like $1785 and $1820 respectively on ebay......a little too high perhaps? Give them a call and I'm sure they'd be willing to beat other quotes you get.

Here's their ebay shop front.
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It looks like I would have to go with either the TKO 500 or the 600, and I was looking around eBay, and I stumbled across a cheaper one.

As I was looking around online, and I found a 70 mustang, that had to make his tunnel larger to fit the transmission, it says "You’ll need to “lift” your tunnel to get the transmission to fit." but then on the following page it say that (Just to clarify, tunnel mods are not required in this era of Mustangs for a TKO 5sp). So does this mean I would have to do the gruesom surgery, or not?

I just ran across this. You can rebuild a T5 transmission with a G-Force gearset upgrade. Which will make the transmission capable of handling 600 horsepower and 500 lb-ft of torque...

If I went that route, then I would be able to use a 3 or 4 speed bellhousing with an adapter plate, which the T5 would bolt to... Also I would be able to go the the junkyard and get a used T5 for $200-500, and then just upgrade the gearset to the more then plenty 500 lb-ft of torque...

I also discovered that the manual linkage is hard to find, so they sell clutch cables to replace them, that are year specific to your car.

Tell me what you think about all of this...

Thank you soo much for all of your insight.

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The Tremec TR-3550's and TKO series are a BIG gearbox, to hold the big gears!!

My trans tunnel needed some surgery to get it right! The mounting points on the Tremecs where they bolt to the cross member are about 1" higher on the extension housing of the gearbox. This results in the back of the gearbox sitting 1" lower compared to a toploader. This lowerers the box overall allowing it to fit better under the trans tunnel. BUT, my car has been lowered quite a bit and this caused a big angle at the front driveshaft uni. ie: gearbox pointing down, driveshaft had to point up to the diff. This caused some ugly vibrations, so I put a 1" spacer under the back of the box where it sits on the cross member, which meant I had to get some tin snips and cut a huge section out my trans tunnel as the whole box now sat higher. See pics.


If my car sat higher, I could have got away with only a fraction of this major hole!! I fabricated a big stainless steel sheet that covers the hole and bolts to the remaining trans tunnel. So my advice on the ambuguity there is that is seems suspension ride height plays a factor. You can measure the angle between the box and shaft after fitting. Ideally you want no more than 3 degrees, and the diff pinion angle wants to be the same (noting that diff pinion and gearbox shaft should be parallel).

Now your are currently running a stock motor which means you really don't need a TKO of any sort, it would just save you $$ in the meantime if you decided to go full up later, which you may never intend to. So, if you only want a cruiser and don't want to give the old 'stang a really hard time, then the T5 would be fine and a lot cheaper too.

What price do they quote for a g-force kit fitted and a total rebuild of the T5?

The other thing a TKO has over the T5 is the very strong casing. There are heaps of extra castings and reinforcements. ie: if your used T5 costs $400 and the kit and rebuild costs $1000 (wild guess) and add on shiping too, I'd invest the extra few hundred bucks and get a TKO.

Those linkage kits look like a good easy option.
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Well, once again you are right... the G-Force kit runs about $1100, so I might as well go with a TKO for a few $100 more... Heres the G-force website...

I was thinking, since the g-force website seems to think that it can handle so much power, as much as a TKO 500... so i wouldnt have to worry about the casing, right? The only reason im leaning toward the T5 w/ upgrade kit, is because you dont have to cut up the trans tunnel, which I really dont want to do, since this car is my daily driver and when I do this swap, im going to want to be in and out ASAP... even though the whole thing will still take quite awhile...

The car will most likely stay pretty stock, I may put in headers in, and after the car is a manual, and I wont have to mess with a torque converter and which stall to pick, ill most likely put in a nice sized cam... but thats about it.

Beside the better gas mileage ill get with the 5 speed, im looking forward to burnouts, and 2nd gear scratches, but thats all the radical im going to get with her... so do you think the case should hold up?

And I cant seem to find the pedals, I dont really care about originality, just some thing that works! Since youve done this before, how long would you say this whole thing would take me after I have everything I need?

What exactly does that clutch cable conversion take place of? Sorry to ask so many questions... Never done this big of a job before... and dont really have trans knowlege, rebuilt by brothers once... and my dad has done a swap before but his car was already a manual... Its the whole clutch pedal, and mounting that up, and connecting it, is whats getting me... theres soo many parts down there...

Thank you SO INCREDIBLY MUCH for your help!
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The strength they quote on the modified T-5 should definitely exceed anything you'll be able to dish at it with your engine and tyre setup, so it still seems like a good option.

WRT to the $1100, is that the kit only? or do you give them a T-5 and for $1100 they supply and FIT the kit?

Doing burnouts really doesn't put a great deal of stress on the car, unless your trying to do them with really fat tyres....spinning tyres are like a pressure relief valve! It's only when you go drag racing and use slicks where all that driveline power has nowhere to go other than the driveline absorbing it all....that's when parts can get hurt. But that being said, I could easily destroy a stock T-5, they really aren't that strong in stock form.

So, the T-5 case should have no worries for your application. Looking at the pics, they seem to be fairly beefed up.

The pedal box setups on those early Mustangs seems fairly complicated in comparison to my early Ford setup. Buy a copy of Mustangs and Fast Fords magazine or similar and I'll bet they have heaps of places that could supply those parts/kits.

The clutches can either use a cable from your pedal to the clutch fork on the bellhousing or a hydraulic tube setup with a small master and slave cylinder setup, bit like a brake pedal.
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In answer to how long it will take?........ideally just a weekend.

Pedal box and fitting new clutch cable parts will be the hardest thing to judge on the time, not sure exactly what you'll need to do the stang.

Put your car on 4 axle stands, the more room underneath you have the easier it will be. Ideally a friend with a car hoist!!

Exhausts can be a pain depending on your setup. Mine was welded up as one piece from the engine to the tail pipe! I had to hacksaw it out to fit the new box :doh:

Drain the trans/convertor oil. Drop the driveshaft (rear diff pinion bolts). Remove shifter and wires off trans / speedo / cooler tubes and starter motor. Put jack under trans and remove cross member and bellhousing bolts. Then steadily slide box back whilst lowering a little. Make sure you don't drop it on your head :hy: 2 people highly recommended. Then remove flex and sandwhich plates. Then it's a matter of fitting all the new gear and setting up the clutch.

Few tips (some from my mistakes :hehe: ):
The flywheel has 6 bolt holes, but they are slightly offset and only goes on one way. Quite hard to torque them can use some chain. Screw one link to where the clutch plate goes (Outer edge of flywheel) and the other end to the block. Stops the flywheel spinning when you crank up the bolts. Make sure you fit sandwhich plate first.

You'll need a clutch alignment tool. Don't fit the clutch disc backwards.

Remember to fit clutch fork & throwout bearing before fitting bellhousing.

When you bolt the bellhousing on, make sure you don't trap any engine wires on the top (you won't see from underneath, so make sure everything is held out the way.

Crank spigot bearing taps in by using the reverse side of a socket.

Mount your shifter after the box is in.

Don't fit an incorrect speedo cog. Make sure its for a T5 or TKO.

Don't forget to fill with oil.

Getting the input shaft to slip thru the clutch disc and into crank spigot bearing can take 10 seconds or all day!! Takes the magic jiggle. It's all about keeping the gearbox parallel to the engine. Once its almost in, you can use the 4 mounting bolts to the bellhousing to keep it square.

When the new driveshaft is in, you want about 20mm or 4/5" of the yoke showing out the back of the rear output shaft seal.

Murphy's law prevails everytime I take on a big job and the time always blows out. Never had a smooth operation yet :hy: .....but don't let that put you off. The satisfaction later makes it worthwhile and you save some $$$. Practise makes perfect.
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Well thank you for your help, im sure ill be posting again for some more help from you, but now its just a matter of time before the money is saved, and the process of buying it begins... I just hope ill be able to find the clutch pedal assembly, because that seems to be a problem with the 69 and 70 mustang, since they are alike, but they were only produced for 2 years... so ill check out the Mustangs and Fast Fords magazines and see what they have... and if they dont, then I guess ill be using the creative side of my brain to rig something up!

Tanks again!
On second thought, what about throwing in a 5 speed automatic? If you perhaps know anything and could share your insight, that would be great! I just like having my options open, since what im hearing is that automatics are faster then manuals...

Read it for your self! --I didnt believe it!

What newer autos would even adapt up to the 351C?

OR if I was simply to add a lock up torque converter to my existing FMX 3 speed transmission?

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