My dad has a 1999 F350 dually 2wd with PSD and a 6spd trans. When you try to shift to 3rd gear it grinds, but if you double clutch it it goes in gear fine. What would cause this, and how much would it be to fix it? Thanks

 

>When you try to shift to 3rd gear it grinds, but if you double clutch it it goes in gear fine. What would cause this, and how much would it be to fix it? Thanks

I'm not much of a transmission guru But I think that he's got a snychronizer problem. Only a tear-down will really reveal.

 

throw some redline in there.

 

I'm not a guru about the exact internals of your transmission either, but Monsta is right. The sychronizers on your 3rd gear are toast. Basically the sychronizers perform the same function as double clutching, they match the speeds of the input and output shafts to accomplish a smooth shift. Check out this link for a real simple explanation.

http://www.howstuffworks.com/transmission4.htm

I had this happen to my '89 F250, it's not the end of the world but it is a signal that your tranny has limited days left.

You have two options.

1- If the grinding just started, you could do a tranny rebuild ASAP. You may save a few bucks if you find a shop that's willing to do the rebuild piece by piece. Check around. Since most shops won't do this, on to option 2. This is your best though if you can get it done, especially if your other gears are in good shape. A good shop will be able to tell you (and show you) the condition of the rest of your tranny and advise you how to proceed.

2- Put in a synthetic oil and just drive it. If you shift smoothly or double clutch the tranny probably has a lot more miles in it. You just have to ignore the annoying grinding sound. However, it will eventually get worse and you'll wear out 3rd gear. At this time (probably much down the road) you have to get the tranny rebuilt. Most shops these days just drop in a rebuilt transmission and send yours off to get rebuilt by someone else. The other choice is a unit out of a wreck, I got lucky and found one in a truck with very low miles and the price was right.

Good luck,

Waxy

 

First question I have is when you double clutch is it just stepping on the clutch twice or stepping on clutch, shifting out of gear, let off clutch and rev engine, step on clutch and shift into gear. It could be synchronizers but it kinda sounds to me like maybe the clutch is bad. I'll admit I'm not a mechanical guru. Either way the transmission will need to be pulled out and the clutch is easier to check first.

 

 

If the clutch is not disengaging all the way it could produce your grinding sound. To check, just jack the back of the truck up. With the tranny in 1st or 2nd push in the clutch and start her up. If the wheels spin, your clutch is not disengaging all the way and needs attention.

Double clutching is the later of your descriptions.

 

Since you did not mention grinding in any gear but 3rd I would suggest that your problem is not the clutch. Also, double clutching would not be effective at solving the problem if the clutch were bad.

SD's have hydraulic clutches, and they are not adjustable. Where does your pedal engage? If it engages two or three inches from the floor, it may be the clutch. Is it hard to put the truck in gear at a standstill? If so, it might be the clutch, but it's unlikely. I've never experienced it in a hydraulic clutch system anyway. At any rate, if the tranny is out for service, there's no better time to do the clutch as a little preventative maintenance.

Simply raising the rear wheels, putting the truck in gear and depressing the clutch may not give you an accurate reading on the clutch dragging as there will almost always be a small amount of friction at the clutch capable of spinning the unloaded rear wheels.

Waxy

 

I disagree, there should not be any drag on the clutch when the clutch is disengaged.

 

can you go from 1st to rev without a problem and it does this easily without binding or grinding ? if you can its not your clutch !
if the grinding is only going into 3rd its a sycro or endplay in the tranny.these trannys are very prone to endplay problems.they use a torque spec with shims and spacers which are locked in place by a torque nut.as they wear or not being setup right from the factory you get your results

Do you have excessive clunk when letting the clutch out in neutral?
if so ,i'd say and endplay issue is causing the resulting syncro problem

The only way to know, is a tear down as stated before!
How many miles on it

Rich