hey i got a 90 f-250, with a 351 and a five speed tranny. every now and then when i put it in reverse, the gear grinds. and it takes a little while before it will go into gear without grinding. i have had people tell me there is nothing i can do except get a new tranny, that sounds a little drastic. so i was wondering if anyon ehas any suggestions. thanks alot.

 

It is probably the syncos. Do you roll back while shifting from reverse into 1st or vice versa? that can damage your syncos. I don't think there is much you can do, so take a few seconds to let it into reverse and make sure you are completely stopped when switching forward-reverse gears.


Primary rig is:
95' F-150 EB 300/6 5 spd with 4" Superlift, MSD, Ram Air, Gibson Exhaust, 32" BFG Muds
NEW PICS IN MY GALLERY!! :-)


Then theres:
88' F-250 Superduty 351 + c6
95' Mercury Cougar 4.6L V-8
80' E-350 300/6 and a
3 spd column shifter. Top speed, 65mph, Go Baby Go!

The newest addition to the Ford family is a 99' Mustang GT 4.6L

 

>It is probably the syncos. Do you roll back while shifting
>from reverse into 1st or vice versa? that can damage your
>syncos. I don't think there is much you can do, so take a
>few seconds to let it into reverse and make sure you are
>completely stopped when switching forward-reverse gears.
>
>
>Primary rig is:
>95' F-150 EB 300/6 5 spd with 4" Superlift, MSD, Ram Air,
>Gibson Exhaust, 32" BFG Muds
>NEW PICS IN MY GALLERY!! :-)
>
>
>Then theres:
>88' F-250 Superduty 351 + c6
>95' Mercury Cougar 4.6L V-8
>80' E-350 300/6 and a
>3 spd column shifter. Top speed, 65mph, Go Baby Go!
>
>The newest addition to the Ford family is a 99' Mustang GT
>4.6L

Never in 47 years have I seen a reverse gear in a manual WITH SYNCROS! If he's having trouble with grinding while getting into reverse there are a couple of things going on here. It sure as heck ain't synchros!

1.) Clutch not releasing enough to let the gears spin down. A properly working clutch when dis-engaged will NOT transmit rpms to the transmission allowing the gear packs to spin down. If the clutch is not COMPLETLY disengaged he will have some grinding.

2.) He's trying to get into reverse too fast. With the clutch bottomed out you should be able to get into reverse from any forward gear WITHOUT GRINDING no less than 3 seconds and no more than 5 with the vehicle stopped.

3.) If the above are ok then he's trying to get into reverse while the vehicle is moving forward. NOT a good idea.

In any event make sure the vehicle is completely stopped, and take your time shifting into reverse.

Larry

 

thanks for the advice, but the griding also happens when i put the truck in reverse before i start it up. my uncles have told me to shut the truck off, then put it in reverse then start it back up, but sometimes it will still grind, but i alway put in in reverse when the truck is at a stand still. but thanks for the advice again

 

I have heard that some of the newer trucks did start putting syncros in the reverse gears but I am not positive. when it does start to grind put the trans in first then go back to reverse and it should slip in easier.

 

I don't think it's a synchro thing.
The reverse gears are straight cut, with the meeting edges of the teeth beveled. There are probably burrs or nicks in the mating edges of the teeth from too many gringing shifts.

I would replace the fluid, make sure the cluth is working properly and that the input shaft is not rotating while shifting to reverse (I don't understand how it can grind with the engine stopped). It is a good practice to shift into second before going to reverse if you have a difficult reverse. It may surprise you what changing the fluid will do, but sometimes the results take a few days/miles to show up.

I have had several 5 speeds (Mustangs, Explorers, F150) that responded well to a fluid change, but only after a week or two of driving.

Hope this helps.

Winford