3.08 or 3.55

[akoldnav]

I am getting ready to change the gearing on my 1988 F250 from 4.10 gears to 3.08 or 3.55. Since I haven't been able to drive these respective configurations, a little help would be appreciated. I don't intend to pull anything larger than my 800 lb boat. I only use 4WD when the snow is on the ground or I am launching the boat.

You guys that have these gears,or have had these gears, what are your feelings about your trucks. What would you do different?

Thanks in advance.

akoldnav

 

[Michael Fowler]

I have a NA 6.9 in my '86. I like the gearing with the 3.55 in mine. I tow a 25' 5th wheel, and w/o turbo, it probably couldn't handle it if I had the 3.08/
The 3.08 gears MAY be OK with the turbo, but I'd be watching tranny temp seriously.
IMO, the 3.55 are the better compromise.

 

[dbensen]

Another option is to keep you eyes open on ebay for a gear vendors overdrive. It would bolt on the back of your transmission and you would get a 20% reduction in your rpm's. Then you would have all the grunt you have now when you want to pull your boat out of the water. Someday you might have a bigger boat. Just a thought. Good luck,
Doug
'86 F-250 4x4
'89 E-250 ATS

 

[akoldnav]

I have tried to find a cheap overdrive that will hook up to my transfer case or go between it for that matter. I haven't actually connected with price and product at this point. Another thing to consider is that I think my differentials are pretty loose. I can rotate the drive line nearly 1/3 of a revolution before contact is felt.

I know a couple of folks here actually have the 3.08 and I hope to hear form them also.

Thanks everybody

akoldnav

 

[Gone Huntin']

Too bad you're so far away, I'm looking to go the other way. I have 3:55's and want 4:10's due to my 285's. I tow a 35' gooseneck and need the lower gearing.

 

[SKimballC]

Gone Huntin', I have 4:10's and want 3:55's. I am in Memphis. Wanna trade? PM me...
As too the 3:08 idea, I know a member named tonkadoctor is running them on his 2wd dually and he loves it. Search for his posts and you'll find what he had to say about the performance and fuel economy.

 

[akoldnav]

Well, the differential shop made my decision for me. 3.08 gears are not available for the front differential in my truck. It looks like I get 3.54 gears. That will be better than 4.10, but not as high as I think I wanted.

I was a little suprised that 3.08 gears are not available for the Dana 50 or the Dana 60. They are available for the Ford 10.25.

Maybe I can watch for a used overdrive later. I should have bought the one SkimballC had earlier this year, but money was short at the time.

Thanks for the help folks.

Akoldnav

 

[Mike]

I dont think you would have been pleased with 3:08's if you tow anything at all. There is a reason they arent available for the D50's and 60's.

 

[f-two-fiddy]

How do the PSD guys get away with 3.08's?
Their trannies have about the same 1st gear ratio?

SKimballC, What's your impressions of the 4.10/ZF5/GV?
How's the fuel economy?

 

[LUCKY_LARUE60]

How do the PSD guys get away with 3.08's?
Their trannies have about the same 1st gear ratio?

SKimballC, What's your impressions of the 4.10/ZF5/GV?
How's the fuel economy?

I have 4:10's and a ZF5 and running emty I get 17 to 17.5 MPG. Now towing my 30' fithwheeler I get 10.5 to 11 MPG.
I don't have a GV and no turbo as of yet, got a turbo just no installed yet.

Jim

 

[f-two-fiddy]

Yeah, I can get 17mpg. IF I keep it below 65 MPH. But heck, at that speed, your getting run over from behind.

 

[SKimballC]

SKimballC, What's your impressions of the 4.10/ZF5/GV?
How's the fuel economy?

I like it. In-town economy is a steady 17 mpg, highway is only about 1 mpg more. I don't use first gear period, though I suppose it could be a granny if I need it. I have been thinking about 3:55's, but I tossed some numbers around and with my 32.5 inch tires I think it would make my gearing a bit too tall. Any taller and I would have to start in first, and it would be annoying having to speed through it. The Gear Vendor's double OD would only be useful at 70, and I don't ever drive faster than 75, if that. My current setup is very functional. I shift between 1600-1800 rpm and can cruise down the highway at 1800 and keep up with the speed limit. Having a turbo and a healthy engine helps too.

 

[Mike]

How do the PSD guys get away with 3.08's?
Their trannies have about the same 1st gear ratio?

The PSD didnt come with 3:08's either. 4:10's and 3:55's for us too. The Super Duty had a 3:73 in the F-250 and I think (dont quote me) a 4:10 for the F-350's.

 

[f-two-fiddy]

I was under the impression that the newer trucks, 99+ had a 3.08 option?

 

[82F100SWB]

That's a big negative. SRW Super Duties are 3.73 or 4.10, DRW have 4.30 optional.