anybody with the 4.2L V-6 have any experience with this swap care to share thier experiences?

I'm considering the upgrade and wanted to know if there are any horror stories out there, or is pretty much everybody who performed this swap happy with the results?

What were the results?
increase/decrease in gas usage?
what is the RPM at 70-75 mph on freeway? (forget about the wheel size difference, I have stock wheels and tires, I know it makes a difference but not that much, I just want to know)
increase/decrease of general drivability?

any information, stories, advice would be appriciated.

oh ya, what would I need to do to correct the speedo?

Thanks,
mearnh

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Since you're making a 15% change (3.55/3.08=1+15.3%), you merely multiply your present rpm by 1.153 -- so if you're now running 1821 rpm at 70 now, you'd be running 2000 rpm with the 3.55 (my last truck with P255/R7016's ran around there with 3.55).

You'd notice first gear shifting at about 87% of the speed that it is now (recriprical of 1.153 = .868; .87 x 30 mph = 26 mph for example) -- and you'll really notice top-gear roll-on improvements with the 3.55.

There's a fellow on this board who is selling a pair of 3.55 with around 10,000 miles or less (??) for a respectable price -- and you'll need a bearing spacer kit, seal, and/or rebuild kit and an additional $300 for set-up labor for the swap.

Usually, when people desire an axle change, the next ratio is not going to give them that 'outstanding' change they're interested in -- but where the current ratio is 'ok', the next ratio change just seems to make things 'better' (for example, I switched from 3.55 on my last truck to 3.73 on my current truck -- both are 'ok', since I changed tires to offset the change in ratio -- so it is not a 'stab-the-trottle-and-smoke-em' goose-bumper).

Long answer for a short question -- but food for thought -- and the price was right.

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Y2K™

XLT SC SB 5.4L E4x4 AW-Disc, 3.73LS, Skid, 7700# HD Towing, Chrome LT-245, Steps, Captain's, 6CD, Tonneau, keyless, Toreador Red, called "Nick"

 

I have a set of 3.55s for sale.Let me know if you are interested or would like more info.e-mail at phlg97@waveinter.com

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99 F 150 4x4.ORP,S/B 4.6 4.10 gears, Gibson 3" cat back. K&N filter. Superchip

 

Seems like a lot of bother not to go further, I would go 3.73's if I were you and then you won't ever have to worry if you want to go to 265's tires or 285's tires for that matter.

But maybe you don't plan to do that and if you get a good deal on 3.55's well....

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2000 F-250 Super Duty, SuperCab XLT, Oxford white with medium grey cloth captains chairs, 5.4L Triton V8 (260 HP - 345 FP Torque version!), 4R100 4 Speed Automatic Transmission, 4 wheel ABS, Deluxe Aluminum Wheels, Trailer Towing Package, Class IV Hitch, Reece load distribution system, Escort Sensor II Electronic Brake controller, Sure Stop towing skirt, "Westin" black powder coated step bars, "White-White" head lamps, Herculiner bed liner, ISSPRO Tranny Temp Guage, Excursion center console, Ford moulded mud gaurds, K&N Air and Oil filter, Amsoil XL7500 5W-30,Air filter minder.

 

Gentelmen-
Thank you for you responces.

Y2K-
Thanks for the calculations. I'm sure they will come in handy while trying to decide if I am going to go thru with this project or not.

jarrettruelz88-
I will be contacting you soon to discuss the gears.

cphilip-
I would think the 3.73 would be a little to Low (or high, I always get those confused) for me. I don't do to much pulling and and am not worried about tire size to much. Becides, those seem pretty wide for me. Don't think I will ever get that wide.
But you never know......

thanks again gentelmen,
mearnh

 

No that would be taller tires not wider as far as the tires go. The 265/75R's are 31.6 inches tall. Exactly the same height as the ORP 17 inch weels with the OEM tires. If you go with 3.55's now and end up going to this size tire later your effective gear ratio will only be 3.36 (or something close to that as I remember). If you go to 3.73's gears now and then went with 265/75R 16's you will have around the 3.55 you want "effectively". Do some homework here before you decide. http://www.4lo.com/

 

cphilip-
I stand corrected, I got confused (again, not to difficult a task for me) about the tires. Yes, they are taller, not wider.

mearnh

 

I too did the 3.08-3.55 swap on my '99 4.2 w/ 255's. The truck, by no means a rocketship, is more powerful thru the gears (5-spd), the power comes on steady w/o the previous "bog spots". All in all, I'm very glad I did the swap (entire assembly in my case to LS axle and all) Doc

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1999 F-150
4.2L, 5-speed,
3.55 Limited Slip,
reg. cab, short bed, Sport Grill,
Pioneer DEH-P4000 CD,
Tinted windows, "blacked-out" factory rims, 255's in place of 235's (tiny tires!)
Delta toolbox
Suuperchipped...more to come....

Wife: 2000 Ranger Trailhead Package
Black & Tinted
5-spd, CD, A/C, 16" 4x4 wheels & tires, 4x4 susp., Westin black nerf bars

 

doc-
if you don't mind me asking, about how much did the swap cost ya?

After I finally found a ford dealership that would do the swap for me, they wanted close to $1,000. I know, I know, the dealership is going to be more expensive, but the truck is still under warrenty(sp).

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I found a guy who works at a Ford dealership in Concord who sold me a complete 8.8 axle assembly, hub-to-hub, 3.55, Limited-Slip, brand new (still on the shipping pallet) for $500. I simply swapped the rears and sold my original 3.08 axle for $200.
However, there is a local speed shop that will sale/install SVO gears for around $400 out the door. So there should something similar close to your hometown. Doc

------------------
1999 F-150
4.2L, 5-speed,
3.55 Limited Slip,
reg. cab, short bed, Sport Grill,
Pioneer DEH-P4000 CD,
Tinted windows, "blacked-out" factory rims, 255's in place of 235's (tiny tires!)
Delta toolbox
Suuperchipped...more to come....

Wife: 2000 Ranger Trailhead Package
Black & Tinted
5-spd, CD, A/C, 16" 4x4 wheels & tires, 4x4 susp., Westin black nerf bars