I have a 1992 F150 5 speed, it will not go in gear. You can a screwdriver in the synchronizer and I can get it to work. What do I need to fix it?

When your engine is running at say 1200 rpm, the transmission is at zero speed with the clutch depressed. When you engage the clutch the first gear is still at zero speed trying to engage with a 1200 rpm crankshaft. In a normal transmission, they have a "synchronizer" which speeds up the gear to match the speed of the crankshaft so the gears mesh smoothly.
When you turn off your engine, the crankshaft is at zero rpm so it can go into gear with the zero rpm transmission. Bottom line...you have a problem with your synchronizer on your transmission. If you are lucky...a transmission shop could fix it without an overhall. But it needs to be diagnosed because it doesn't sound good.

Get the transmission serviced, either a worn gear, bearing, or bad synchronizer.

transmission synchronizers most common cause of transmisson noise in certain gears, and not others, might want to check the gear oil level. Transmission rebuild required. To read about them and what they actually do, then here is a good read:
When you shift gears in your standard shift car, you move a rod that moves a fork that engages the gear. Depending which gear you're shifting to, a different fork does the job. The fork moves the collar to the desired gear, and dog teeth on the collar mesh up with holes on the gear in order to engage it. You engage reverse gear through a separate, small idler gear. The reverse gear always turns in the opposite direction of the other (forward) gears.
In years past, double-clutching was common in order to disengage a gear, allow the collar and next gear to reach the same speed, and then to engage the new gear. To double-clutch shift, you pushed the clutch pedal to free the engine from the transmission. Then the collar moved into neutral. You released the clutch and revved the engine to get it to the right rpm value for the next gear so the collar and the next gear spun at the same rate to allow the dog teeth to engage the gear. When the engine hit the right speed, you depressed the clutch again in order to lock the collar into place on the next gear.
Modern cars use synchronizers in order to avoid the need for double-clutching. A synchronizer, or "synchro," lets the collar and gear synchronize their speeds while they're already in contact but before the dog teeth engage. Each manufacturer's synchro is slightly different than the others, but the basic idea is the same. For instance, a cone on one gear will fit into a cone-shaped depression on the collar. The gear and collar synchronize their speeds thanks to the friction between the cone and collar. Then the outer part of the collar moves out of the way so that the gear can be engaged by the dog teeth.

I am assuming its a manual, if it is having trouble fitting into multiple gears, its probably the idle gear, which is the one that should be going an appropriate speed when you are trying to mesh gears (with the help of synchronizers which could also be the problem) and if its not going the right speed, then it will have some difficulties meshing. try this method. when you are going to switch gears, depress the clutch pedal, pull it out of gear, then when still in between gears, let the pedal out, then depress the pedal again, and select your gear. this is the "double clutch" method that commercial truck drivers use with transmissions that do not even have synchronizers in them and should work for you. if this does not work (or if it does but its such a pain to you that you still want to get it fixed) then go to a transmission shop and have it looked at

Is this a new truck to you? Some manual's have a manual reverse lock-out, meaning you have to engage the lock-out to shift into reverse. This is usually done by pulling up on a small lever just under the shift knob.

Otherwise, the lock-out is inside the transmission and if that breaks, the transmission has to be removed to fix it.

The other possibility is that you don't have a synchronized reverse gear. It will not automatically sync with the engine speed. Try lightly putting it in reverse while letting the clutch up to the engage point, you know, right where the clutch first starts to grab.

If this is a manual transmission, check the clutch free play which should not be much more than about 1/2 to 3/4 inch. If ok, then you may need to replace the third gear synchromesh mechanism within the transmission. This entails a tear down of the transmission, so it would not be classified as an easy fix. Hope this helps!

A synchronizer for 5th gear is bad,needs to be replaced,the transmission needs to be removed ,and repaired.

there are synchros on all the gears in this trans, I am assuming it is the Mazda built aluminum case unit (M5R2)

They deteoriate - trans needs to came all apart

Suggest you check the fluid level of the transmission first. Remove the fill plug, and see if it is Below the proper level. Do Not fill at this time! There is a reason for this.

Then I would suggest draining the fluid. You are also looking for brass fragments in the fluid. Drain into a three quart metal, or plastic drain pan. (They are approximately 18 inches across, and 4 inches deep)

1.Manual transmissions use Synchronizer's made of a brass alloy. The synchronizers have tapered teeth, that the nose of the teeth can be worn down. Also a tapered surface on the synchronizer, that can be worn down. Brass fragments in the transmission fluid is a sign of this wear.

Some brass 'dust' will occur as normal wear. A large accumulation means you have problems. Transmission is hard to shift, is one of those symptoms due to this.

This link to an animated working of a five-speed manual transmission, may help to explain how the components interact with each other, and also help me to explain the Synchronizer/s.
(From Howstuffworks.com - Auto- Under the Hood - Transmissions and Drivetrain)

http://auto.howstuffworks.com/transmission3.htm

Looking at the animation, observe the 'gold' colored parts. In particular, observe the the pair of gold colored teeth at the rear. (The teeth are in a vertical row, going up and down)

Now also observe the blue colored teeth next to them, on either side. (On the spinning gears)
You are looking at a side view of the transmission, and also a side view of the Synchronizers.

The synchronizers are round just like the gears. They have a Female tapered surface where they meet the gear. The gear has a Male tapered surface on the outside of the gear, that matches.

When the female tapered surface of the synchronizer meets the male tapered surface of the gear, the friction contact makes the synchronizer start turning the same speed, as the gear.

Helps the gear being shifted into start turning also, and the - teeth of the synchronizer, - gear to be engaged, and - already turning components are synchronized to each other. They will be all turning the same speed, so shifting will be smooth.

This shows you Synchronizer rings for a 4-speed Muncie transmission,

http://cgi.ebay.com/ebaymotors/MUNCIE-4-SPEED-BRASS-SYNCHRONIZER-RINGS-1963-TO-1974_W0QQitemZ360137693405QQcmdZViewItem?rvr_id=&itemid=360137693405

Enlarge it for a better view.
See the teeth going around the synchronizer ring? Notice that they are pointed, or V shaped. When the nose, or tip of this V is worn down, a manual transmission is hard to shift.

Also observe the flat landing on top. (In this view it's on top) The flat landing has three rectangular cutouts in it. (There are used for Detents)

Come from that top landing, down the side to the teeth. This Side has a tapered surface. Tapered ever so slightly, that it is not readily visible in this photo.
When this tapered surface wears down, the transmission is hard to shift.

Summation?
1.Low fluid will cause hard shifting. It will also cause abnormally high wear of the synchronizer rings, (Synchronizer Rings are also referred to as 'Blocker Rings')

2.Worn Synchronizer Rings,
Broken or worn Detent 'buttons',
Broken Detent Springs,
and worn Synchronizer Hub's,
will cause hard shifting.

Should you not have an abnormal amount of brass shavings in your transmission fluid, and found the fluid to be low, you may want to just replace the fluid to the proper level, and see if this works first.

If so, I suggest contacting your Ford dealer, and see what the proper transmission fluid is for YOUR Ford Ranger. They will go by THE transmission is used in your truck, and will have any updates if better fluid has been developed since your truck was made.

I know dealers are expensive to buy from sometimes, but I implore you to use the transmission fluid they recommend.
It will have special additives.

sounds like synchronizer ring assbly

shack