Vibration/low power in 5th/overdrive only
 

Ok, I have a buddy that is having a vibration in his ranger with a manual trans only when he is in 5th gear. When he's in 5th it seems like he's low on power too and can barely pick up speed. All other gears are fine with no vibration and good power. I think I've found that the 5th gear is on the counter shaft on this trans, m50d-r1, could the bearings on the counter shaft be going or gear lash for 5th gotten bigger somehow? any insight or experience is welcome.

What year, engine, rear axle ratio, and number of miles for this Ranger?

All of this information will be helpful for us to help you out.

Oh sorry bout that. It's a 1996 Ford Ranger 2.3l engine with a M5OD-R1 manual trans and 190,000 miles. I'm not sure on the axel ratio. Is that on the door sticker?

Regarding the vibration, if it feels like it originates in the drive train it could indeed be bad bearings. If it originates in the engine it is likely to be a cylinder misfiring, which would certainly result in a lack of power. A four cylinder doesn't produce a lot of torque to start with, and in overdrive any defect will be quite apparent. If a miss, do a compression test, look over the plug wires, plugs etc. the usual suspects.

Well, I have an AutoEnginuity scan tool with the ford enhancement for my powerstroke so I hooked it up and read the codes and It has one for O2 heater circuit only. It doesn't feel like a miss and fuel trims hover around +2 to -2 so i'm thinking a miss is unlikely. Checked plugs and all are less than a year old and look great.

I started thinking maybe a weight fell off the driveshaft and became unbalanced at first but wouldn't going the same speed in 4th gear produce a vibration if that was the case?

wouldn't going the same speed in 4th gear produce a vibration if that was the case?
I would certainly think so. Does the tranny howl or whine? I wish I was close enough to ride in it and listen, hang in there and we will try to get it figured out.

It'll be low on power if you're trying to go 35 mph in 5th gear... you really need to wind that engine out to reap the benefits of 5th gear. My 2.9 is the same way, 50 mph in 5th gear is a dog.

Josh

At what speed is 5th gear causing this "vibration"?

Well it's done it at all speeds that we've shifted into 5th. Probably anywhere from 40-60 mph.

He's had this truck for 5 years now and knows the ins and outs of how it drives pretty well. About a week ago he noticed this problem and called me. He's staying out of 5th for the time being.

Anyone had their M5OD rebuilt and know how much it cost them?

Have you looked for tell tale signs of failure in the trans oil/fluid?

Not yet but we're going to change the fluid soon and see whats in there.

Problem fixed. And it was a bad rear ujoint. It was locked up tight enough that off the truck that you couldn't move it by hand. It's wierd cause riding in it you would swear that it was right under you at the transmission area.

Replaced both ujoints and changed the fluid while we were at it and it's shifting and driving like new again.

Thanks for all your help guys.