I have a 93 F350, 4wd 5 speed and high/low range gearing, with the 460 engine. We pull a 32 foot (11000lbs) RV Trailer perhaps only about 1500 miles per year. The rest of the time is local driving with no trailer....

Needless to say the gas mileage is killing me, but my real problems have to do with the transmission. The low range is great for climbing trees and the high range is also very low, so low that I never use first gear even in the high range position. So I have been thinking about changing the gear ratios but have no clue as to the cost of doing this.

But now the bad news part. While just cruising on the flat while towing the trailer, all of a sudden my fifth gear starts making a hell of a buzzing rhythmic sound. I had to wonder if the gear that I missed awhile back had damaged a tooth on the fifth gear. It makes the sound in low range fifth as well. It still pulls ok and doesn't seem to bind, but I don't dare drive it in fifth gear as it sounds rather expensive....

So anybody have any idea how much it would cost to fix the fifth gear or just change the high range ratio... I don't know exactly whether the gears are 355, 411 or something in between. But in high range fifth gear at 60 mph, the tach is about 2200 or 2300. Forth in high range at 60 is about 2800 or 2900. Also, I am not convinced that changing the final gear ratio with fix the fifth gear problem...

Help! any good ideas out there that won't cause me to sell the whole truck due to high cost. Also can I get it fixed with better gas mileage?

 

Since you have the ZF 5 speed, I can already tell you what the problem is. The ZF 5 speed that was in my truck did the same thing, and it wasn't anything broken, but the actual shaft for the shifter was out of alignment of where it needed to be, so the 5th gear made a buzzing or a whirring noise. There was a recall in the late 90s to update the part I guess, but the PO of my truck neglected to get it done. I guess theres no negative effects, but it does sound annoying and it sounds like something will break.

 

Wow, ok that sounds promising, is there anything that I can crawl under and see if this is the problem? Something to look for and maybe adjust slightly...?
Thanks for your time, it is appreciated.
Don

 

So you have a 460 im guessing??

Need to find out what gearing it has now.

 

By low range do you mean the 4lo setting on the transfer case?

No one uses 1st gear, it's a granny gear used for extreme climbing or extreme towing (like trying to get a semi moving, not heading down the road).

Changing the final gear ration won't fix your 5th gear problem but you're running the same RPM's at the same speeds I am with my 460/ZF5 pickup.

What fuel mileage is killing you? I'm getting 13-14mpg and that's a little higher than average, i'm ecstatic to be getting that.

 

Im not sure that you can see anything from crawling under the truck, as im not exactly sure what causes the noise, but I really wouldnt worry about it too much. there has to be something that can be adjusted, but you would probably have to pull the tranny out and it would be a pain in the butt. the guy i bought my truck from said it had been doing that since it had 40,000 miles on it, and i bought it with 90,000 and it has close to 100k now. I'll see what the guys I work with say about it, and if they give me any good info, Ill definitely let you know what you can do.

 

Judging by the info provided I'd bet your truck has 4.10 gearing.. take a look at the axle code on the drivers door pillar and compare it to this chart..Ford Axle Code Chart .: Articles

Changing to 3.55 would certainly help fuel milage but it could be expensive, it requires some special tools and knowledge and can take several hours per axle, and you have a 4x4 so both front and back have to be changed so it could run $500-$1000 in labor alone with another $300-400 in parts. An alternative that could be significantly cheaper would be to simply swap out the complete axles with those from a donor truck, no special tools needed but these are big heavy axles so it's not going to be light work if you know what I mean.

 

Ok, thanks for the info. And thanks for any other tips you might find.
What is so anoying about this is that the tranny has been just fine for 95,000 miles and then all of a sudden it starts making a horrible noise.
It also has me ticked off because the gasket for the egr valve has failed AGAIN, in only about 2 weeks of use. So now I have an exaust leak too.

Best to you.

 

Yes, Low range is the 4lo setting. Ok, the 1st gear is handy to move the rig at a light on a hill.... But other than getting myself out of a ditch or pulling a freight train for a Ford commercial, I just wish the 4lo was a little more practical... First gear in 4lo is slower than my watch!!

Thanks for the feedback
Don

 

Yes, you called it, the axle chart indicates a 410 ratio. Well I guess the cost to change just isn't worth it. Although this truck may be old it sure looks good. And since I am a senior citizen now, my days of crawling under the truck are limited... Thanks for you help though..

Don

 

I'm getting the feeling that this is one of your first 4wd trucks? Low range is supposed to be slow, the slower the better. I have the same setup as you, engine, transmission and gearing. The low range was one of the big selling points for me, if you ever go off road, I mean really off road you'll appreciate it. And just to make sure you know, all 4wd trucks have Hi/Low gearing.

You say you want low range to be more practical, what are you wanting to use it for?

The problem with our trucks is that the ZF5 transmission doesn't have much of an overdrive. Actually I would be fine with having all the gears spread a little but the overdrive especially could do more.

 

The guys i work with at the Ford garage said that they "take the upper part of the tranny off and put a shim in there somewhere to correct it, but for what it costs to get it done, you might as well put up wit the noise because all of the garages want to charge you an arm and a leg for it now" I would definitely check into the egr valve gasket going out especially that quickly.

 

Yep, I know what your saying about what did I expect from a 4wd. I guess it is because we use the truck primarily for hauling our fifth wheel RV that weighs over 11000 lbs. We bought it used and at that time we had to choose by price and capability. So we ended up with a truck that could pull the trailer, but it can also go offroad if I wanted to do that. We really only need to be able to pull the RV. So I also have a great offroad vehicle, but unfortunately we don't need that......
So if anybody wants to trade this great F350 4wd/hi/lo for a comparable dually diesel that can haul a Fifth wheel, that would be great.

By the way, I have used the 4wd/lo to pull the rv out of a snowy dirt muddy parking lot in the middle of winter, (NO PROBLEM!)

Thanks again,
Don

 

Your truck and about 5000-7000 in cash.

If you're towing, you don't want to change the ratio. You will lose a lot of power with taller gears. Your truck sounds like its set up well for towing an RV that size. I wouldn't change anything.

But do not tow in overdrive with a ZF 5-speed!!! They are not made for it. The overdrive gear is weaker than 4th and if you keep towing in OD you will need a new transmission sooner or later.

 

Thanks for the info, yes I will wait (stall) on fixing that until I win the lottery.

Anyhow, here is what she looks like...