bad clutch or bad tranny

i have a 90SC manual tranny with 147000 miles on it. when i got the car i was told it might be the origianl clutch, but anyway. from first to second it grinds(slips?) and from second to third it grinds. Is that a bad clutch or does the tranny need to be rebuilt. my machanic seems to thinks its just the clutch. your input is greatly appreciated. thanks

phil

If it's only between specific gears, it can't be the clutch. Sounds more like the sychros (common problem with the M5R2).

try a clutchless shift if it still grinds then you know its not the clutch

My not be either. Are you sure the clutch hydrolics (the master and slave cylinder) are working to fully depress the clutch when you shift? That could cause grunching between shifts..as the clutch is not dis-engaged all the way.

Check the fluid (don't let that black boot in the resevoir fool you.

Clutchless shifting a sychroed tranny will kill the sychros. Very bad idea. As I said though, if there were a problem with the clutch it would do it between every gear, Not just 1-2 and 2-3 as he described.

thanks for your input. i am going to recheck the fluid, and also look into making sure the clutch is being fully depressed and disangaged.

also...

what exactly do the syncros do? and if they are bad, does the whole tranny need to be rebuilt? thanks

I can't remember the technical definition but whenever you shift the synchros are engaged. Without them it either won't shift or it will grind like hell (which after time will mess up the gears) The synchros are pressed on the shafts with the gears so a rebuild is required to change them. The only other thing the service manual shows for this is the pilot bearing binding but hell its in the back of the block. You have to pull the tranny to get to it.

Try new tranny fluid. Most Ford's now days use ATF Mercon in manual transmissions. Be sure to add 1 bottle of Ford Friction Modifier to the fluid.
As for the clutch, it is a similar hydraulic setup used in my 93 Ranger 4X4.
My clutch went spongy, I got some grinding. I bled the clutch (brake fluid) goes in this. The fluid was filthy. I kept bleeding it until the fluid was clean.
After that it was great...for about 1 year. I bled it again. It only lasted 6 months. The more I bled it, the less time I got out of it. Finally I replaced the master cylinder in the firewall. Be sure to bench bleed this item before you install it on the car otherwise you will never get the air out.
That lasted 6 months, then it got really bad. I tried to bleed it and lost all pressure. The slave cylinder inside the bell housing had finally choked.
I was hoping it would've been the master, but the dealer said slaves fail more than masters.
I replaced the clutch disk, pressure plate, hydraulic hose, and slave cylinder. Note: The release bearings are usually integrated into the slave cylinder now.
While the tranny is out, you might as well have them pop in a couple of new synchros.
Pay me now or pay me later, if you don't get this looked after, you will either break the tranny or get stuck somewhere on the side of the road with no clutch. I did.
I have to say that the truck gave me over 2 years of "advance notice" that the slave cylinder was failing.
If you have difficulty sometimes putting it into first gear at a stoplight then it's most likely the hydraulic clutch.

one clutchless shift will not kill the tranny as a matter a fact why is clutchless shifting bad for the tranny ?? and you are right if it is grinding in a few gears then it is not the clutch

The Synchros do exactly that.
If anyone here has driven any kind of old tractor, they will have realized that any gear you try and shift into once the tractor is moving grinds. This is a non synchro-mesh transmission. Wouldn't be a very good idea for a car huh?
For example....when you are in 1st gear and revving 3000 rpm, the transmission input shaft is spinning at 3000rpm. The power is transmitted through the 1st gear set to the output shaft of the transmission, which is connected to the driveshaft. If the ratio is 3:1, the driveshaft is spinning at 1000rpm.
Now, you want 2nd gear. When you push the clutch in and pull the stick into 2nd gear, the syncro's job is to get the 2nd gear set shaft spinning at the same RPM as the input shaft before the gear sets mate. This allows the gears to mesh in quietly, at the same RPM, and no grinding occurs.
If the synchro is worn out, the two sets of gears will not be at the same speed when tooth contact occurs grinding is the result.
Anyone that bullies around a tranny with worn synchros will chip or break gear teeth and be sorry later.
Usually you can just replace the faulty single synchro that you are having trouble with.
Since you have it apart anyway, the best way is to do 2nd, 3rd, for sure and maybe 4th too as well as any bearings showing signs of wear.

I don't remember why shifting a sychroed tranny without the clutch will kill the synchros. Thats what I was told by my father. He knows his ****. Rebuilds tractor trailer trannies/rear end/engines for a living.

really i was always told that when u are able to shift your tranny without your clutch you tranny is in perfect synchronization so i dont see why it would put stress on your syncros it would be coo to find out why you can or cant

synchronizers are there to help in the synchronizing of the gears while shifting. It really sounds like a beat clutch to me. It will be more prone to do that in lower gears than higher gears due to the vehicle speed and engine RPM. When synchronizers go bad the transmission will pop out of gear while deaccelerating. And yes never shift without using your clutch at high RPM's. This is not a good idea. You could probably be Ok while shifting at lowere speeds but I wouldn't push it. Either way if the clutch isn't disengaging all the way it will grind while shifting because the shaft is still partially engaged. Those 5 speeds are expensive and i wouldn't risk F'ing it up for anything. Plus they are hard to find these days. They haven't produced those things in quite some time now.