"A brief guide to MTX Disassembly"

Submitted by Bizzy

MTX-IV Disassembly Procedure

MTX-IV Disassembly Procedure

Brief instructions on how to disassemble your MTX transmission.

Updated 02-08-06 ~ Bizzy

While the MTX trans isn't that complicated, it is a rather complicated task (for me) to tell someone how to disassemble it.  I could show you in 5 minutes.  But also keep in mind that there is an order in doing things and there is a reason for the order.

Below you will find illustrations on the disassembly process, however the responsibility, liability and risk is upon you if you decide to take your trans apart.  In other words, I assume no responsibility if you screw something up, lose a part or otherwise can't get the trans put back together or if something goes wrong with the trans after you get it put back together.  I also have not gone into great detail on these instructions, there are not (not yet anyway) instructions on how to clean the internals and perform the re-assemble, so you do this at your own risk.  I will try to finish the whole write-up ASAP, but it will take time.   If you run into a boggle, feel free to email me if need be.

Having said that, here’s some illustrations for you to go by.

The first thing to do is to sit the trans as positioned in the picture below.  Insert a drift punch into the hole in the shift shaft and place the trans into neutral if it isn’t already and move the trans into the neutral position.   This is an important step in order to make it easier for the removal of some of the internal parts.  Failure to do so and you risk damaging the synchros!!

Trans into Neutral. THIS IS IMPORTANT!!! 

Second thing to do is place the trans on a bench with the bell housing side down.  Prior to that you can remove the shift fork assembly or not.  To gain access to the internals it is not an absolute necessity however with the fork in place you’ll have to move it out of the way when removing a couple of the case bolts.  It IS a good idea to remove it so you can at least clean the assembly and check your bushings to make sure they are good.   They're cheap enough and it would be a good idea to replace them.  You can also remove the backup lamp switch as well.  Again, you don't have to in order to open the trans up.

Remove the fill plug by inserting the square end of a 3/8 ratchet into the plug and loosening as you would any bolt.  Rightsy-tightsy, leftsy-loosey.

Remove fill plug

Remove the reverse idler retaining bolt and the fork interlock retaining bolts.  LOOSEN (ONLY LOOSEN) the detent plunger retaining bolt.    It's a good idea to keep a plastic bag handy to keep all the bolts together so they don't get lost or misplaced.  Do NOT completely remove the detent plunger retaining bolt.  (Or do.....but you'll be soooooorrrry.)


Reverse idler retaining bolt. REMOVE


Fork interlock retaining bolt. REMOVE

Loosen only

Detent plunger retaining bolt. LOOSEN ONLY!

Now remove the 15 (sometimes 16) case bolts.  Pay attention if yours only has 15, you'll want to replace them into the same holes.

Remove case bolts

Now it's time to separate the case halves.  There are two spots on the case that can be used for prying, I use the same tire iron (AKA "Tranny Tool") to pry the case halves apart.  Under NO circumstances should you insert the tool between the mating surfaces of the case halves.  Those surfaces must stay true in order to seal properly.  If you scratch or gouge those surfaces your tranny will leak, so take care during the separation process, use only the pry spots in the pics below.  NEVER set a case half on the ground on those surfaces.

Illustrated below are the areas that are safe to pry the case halves apart.

Pry here

Pry here

Locate the reverse idler gear assembly.  Take a small flat tipped screwdriver and remove the C-clip and set it aside.  Remove the arm from the assembly.  Take the center shaft in one hand and the gear in the other.  Lift up on the center shaft, once it clears the case you can remove both the gear and the shaft.   Generally I will reassemble the shaft, arm and C-clip just to keep the parts together, the C-clip is easy to lose and that's not a good thing.

Remove C-clip from reverse idler assembly

Next you need to remove the spring pin that holds the shift lever spring assembly.  Use a drift punch to drive the pin from the case.  MAKE SURE THE DRIFT PUNCH IS NOT TOO SMALL!!!!  You do NOT want to get a punch stuck in the middle of the spring pin, trust me.

Remove shift lever spring pin

Remove the shift shaft lever assembly.  I usually use an every day tire iron to nudge the center shaft outward a little bit.  Once the shaft is out of the case enough you can catch the hole in the shaft with a drift punch or small screw driver.  From there you can manually remove the shaft.  Once the shaft comes out enough you can catch the 2 springs.  Depending on the mood of the person who assembled your transmission (or Ford's stock), you may or may not have 2 springs.  It seemed luck of the draw on whether the reverse kickback spring was installed or not.   There will be at least 1 large spring on this shaft however. 

*Important note:  When removing the shaft it is a good idea to put your finger over the hole in the shift lever assembly.  Sometimes when the shaft is removed the detent spring will shoot the ball bearing out of the hole.  It doesn't come out with a lot of force, but you don't want to lose the ball bearing.  Rarely have I seen this, but it has happened.

Once the shaft assembly is out, remove the lever assembly.  At this point it's just sitting there with nothing holding it in place.

shift shaft lever assembly removal

Now it's time to remove the main gear shaft assembly, shift fork and input shaft.  Take great care when removing these parts, they are heavy and if mis-handled you run the risk of popping a synchro apart.  (Don't drop them!)   With your left hand grasp the shift fork firmly, with your right grasp the assembly firmly and as evenly as possible across the entire assembly.  It's a good idea to put your fingers on the gears rather than the synchro since they can and will pop apart.   Lift on both the fork and gear assembly and input shaft to remove them all at the same time.  They're heavy so take care when doing so.  When lifting the gear shafts, lift straight up until the fork and gear assemblies clear the case and the funnel in the case that's under the race for the bearing.  The funnel is made of plastic and can be damaged if mishandled.  Set the gears and fork aside.

Main gear shaft assembly removal

Remove the 5th gear shaft assembly and fork.  They lift right out and are easily removed.  There is another plastic funnel under the 5th gear shaft assembly as well.

5th gear shaft and fork assemblies

At this point you can remove the differential assembly from the case, it just lifts right up.  It's heavy so take care to not drop it.

Remove the diff

Now is a good time to check the bearings and bearing races, replace your axle seals, input shaft and shift shaft seals.  Remember that if nothing else, you should at least replace your input shaft seal since it is the only one that can't be done from the outside.  Now would also a good time to install a drain plug as well.   I never did enjoy doing those while the trans is installed on the car, MUCH easier with it on a table.  The drain plug instructions can be found on shotimes.com.

Assembly is pretty much in reverse order, however there are a few tricks of the trade that help to make things easier.  I'll try to get a write up on that on another day.

Oh......and one more thing.  When you seal the case back up NEVER, NEVER, NEVER, NEVER use RTV.......it'll come back to haunt you. 

Use Permatex Anaerobic sealant ONLY!  (Blue tube, red sealant.)

Permatex Anaerobic Gasket Maker

Good luck!