I have a 91 F150 w/4.9 & 4spd. I believe the slave cylinder is bad. From what I have read and from going under the truck, it appears to be an internal slave cylinder. I bought a replacement part this evening, but it appears they gave me an external unit. According to Oreilly, Advanced, & RockAuto.com, the pictures of the part I got are correct for a 4spd. However, from being under the truck, the pictures of the internal slave cylinder for a 5spd look like the part I need.

How can I properly identify the right transmission to make sure I get the right part? (and yes, there are only 4 gears....I tried shifting to 5th a couple of times out of habit from driving my jeep and 5th gear is not there!)

Edit: After calling around all morning I found out there are two slave cylinders for 4 speeds (at least in the 91 model). Every parts supplier has the external unit for around $30 bucks. I called the local dealer and provided them with the barcode info from the transmission. After me explaining to him he too was trying to sell me an external unit, he finally input the barcode info and found the internal slave cylinder.....for $210. Re-called all parts suppliers, and of course it's a dealer only item. Just for the record, the internal slave cylinder for the 4 speed trans looks just like the slave cylinder for the 5 speed, only difference is that the bleeder valve is on top of the input line on the 4spd and on the 5spds, the bleeder valve is below the input line.

Maybe this info can be helpful to some one else too and save a couple of unnecessary trips around town.

 

Just trying to verify some more info here.....I found out that my 91 has what the dealer refers to as a Mazda R2 tranny....apparently the only year that FMC used this particular Mazda 4spd tranny from what local dealer says. In trying to research tranny for alternative slave cylinder provider, I keep finding info on Mazda M50D 5 speed tranny that was apparently used quite a bit. Trying to learn about options, and it seems people change the M50D for a ZF 5spd on other forums and seem to think it is better all around tranny. I have ordered the slave cylinder for my 4spd from the dealer (and got the parts guy to sell it to me at wholesale to save $60)....but, I am going to use truck for highway and pulling my aluminum bass boat.....my question, am i wasting money on this tranny? Should I swap for the ZF? Is it a direct bolt swap? If the internal slave cylinder actually is different for 4spd and 5spd (1/32 difference in internal bore and placement of bleeder valve is the difference from what I can tell, beside the huge price difference), how is the swap even possible?

 

I have the M5OD in my 95, likewise a 4.9, and I can't really complain. Yes, I'm eventually switching to a ZF-47. BUT, I'm gonna be hauling stuff a lot heavier than a bass boat. What is your diff. gearing? Should be a little metal tag attached to the diff, lower left hand corner (on mine at least) gives the gear ratio and the number next to identifies your diff (usually 8.8)
But short version, if you're gonna be on the highway a good bit, and not pulling anything bigger than an aluminum bass boat, you should be fine if the Mazda 4 is anything like the M5OD. M5OD has a good highway gearing too, I'm getting round about 20 MPG, and still ain't got it 100% right

 

I just had my internal slave cylinder replaced on my M5 trans. It requires taking out the transmission, so if you are going to upgrade, if it is possible to do, then now is the time

 

I think you're meaning there's one w/ internal and one w/ external? What's the trans code? My Chilton only lists (and it could be wrong) Warner (T-18, T-19 & T-19C) New process 435 and Ford TOD as the available 4 speed trannys? Also, the M5R2 was mentioned. On the M5OD, the bleeder screw is above the line to the MC, just checked mine. Could it be that a PO disabled your 5th gear? Or the fork is stuck? I can't find mention of a Mazda 4 speed anywhere, unless that's the new process?

 

Aha! I figured it out (I think) according to FordWiki, the designation "R2" was used fo the Heavier duty M5OD, "R1" was for the one used in the rangers and whatnot. Go JACKSLAP that guy at the dealership for over charging you, and go get an M5OD slave cylinder from O'reillys.
Your 5th gear may be disabled, or stuck or whatever but I bet a dollar against a donut that you do in fact have an M5OD transmission with a problematic 5th gear.
Unless you got a hold of some unheard of tranny that's gonna make me look like an idiot for saying all of this
Just for the record, I'm just trying to figure this out, not trying to sound like an ***** clown or anything

 

Take a picture of it, I'll tell you what it is. Most likely the M5OD. Don't know of any 4 speeds with an internal slave.

 

My Haynes manual, O'Reilly's, Advance Auto, AutoZone, and two local part houses that actually have experienced parts guys like the old days can only find parts for the T-18 and no mention of any other 4spd tranny......all have the external slave cylinder for $35....which is for the T-18. The tranny is a true 4spd w/no 5th gear. I went to the parts dept of the local dealer and it even took him a minute to figure it out. I don't have the tranny code with me right now, but that is how they figured out it as the Mazda R2, not and M50D, not an M5R2, etc....again, apparently 91 is the only year this tranny was used. I picked the part up from the dealer today and the mechanic had the old one out and they are exact. However, now that I have seen how it goes in and compared the old one to the new one, I think the internal slave cylinder for the 5spd would have worked....I was thinking it went on w/the bearing to the trans side which puts the bleeder on the bottom. The bearing actually goes toward the motor which puts the bleeder valve on top of that one too....and with only 1/32 of difference in the bore, I wold have taken my chances to try it 3 weeks ago and saved another $60.

 

So is your truck back to working order? I know I'm happy to have my truck back! Was a long month without it

 

Learn something new everyday
Hate that it cost you that much headache and $$$, any "dealer only" parts are ridiculous, especially Mazdas. I had to buy a "dealer only" thermostat for an MX6 once, nearly $40 for a friggin thermostat.
Glad you got it straightened out though