Hello,

I have an 05 f-150 super crew 4x4 with the 5.4L and the 4r75e tranny. With 33 in tires and the 3.73 gear set it runs 1900 rpm at 70 mph. I have ordered a new torque converter with a 2500 rpm stall. I am concerned about choosing the appropriate gear set to compliment the torque converter and to compensate for the taller tire. I am considering a set 4.10 or 4.56 gears, leaning toward the 4.56 setup. Should I be concerened with the converter at highway speeds? What about heating problems ....

The truck is driven mainly around town, howerver I do tow a 21 ft boat to the lake 10-15 times per summer. Any comments would be appreciated.

Thanks

 

What cam did you put in that engine to need the higher stall?

For 33's I'd say 4.10's would probable be optimal BUT I personally don't think the difference between 4.10's and 3.73's is noticable enough to spend the $$ to change gears. If you went to 35's then I'd step it up to 4.56's.

 

I have not put a cam in it yet. I spoke with a tech at comp cams and they are releasing new cams for the 3V engine some time in the near future (30-90 days).

I was hoping to improve acceleration with the new torque converter while keeping it drivable.

Thanks for the response.

 

Don't touch the torque converter unless you put in a new cam. Even at that you need to make sure the converter is matched to the cam you install. The stock converter is set up to stall where the engine is starting to make good power. If you increase the stall beyond that you'll end up creating massive heat and revving your engine beyond its optimal power range. It doesn't make acceleration faster, it just winds up making the throttle feel mushy, eats more gas and causes more heat in the tranny. Regearing is really what you'll want. Maybe someone who knows the final overdrive ratio on that truck can post some RPM scenarios for you with different gear sets to show you some options.

 

I was afraid of that. So I'll will scrap the converter idea for now untill I get some specs on the cam and go with the gears instead.

I appreciate your input.

 

For what it's worth the transmission ratios are as follows:

1st - 2.84
2nd - 1.55
3rd - 1.0
OD - 0.7

Thanks

 

Damn overdrive is nice. With the overdrive and 33's you'd be looking at about 2050 RPM at 70mph. If you stepped it up to 4.56 you'll be at 2275 a@ 70mph. Given those figures I'd definitely go to 4.56's on your truck, or if you plan to step up the tire size in the future, like 35's or 36's maybe even 4.88 which would put you around 2450 with 33's @ 70mph.

 

The 4.56 gears are on the way. If any one else is interested I went with Motive Gear. They make several different ratios as well as basic and master install kits. for front and rear. I was able to order thriugh Summit Racing (talked to a kid named Carson he is aware of what motive offers now). It's somewhat difficult finding parts for the 04-05 f150s. The after market has stepped up, but it seems that a lot of the resellers don't know what is available beyond your basic bolt ons. So as a result we end up doing the leg work. Oh well such is life.

Thanks man!

 

It's probably too late now, but if you search the Mustang message boards, swapping in high stall converters is pretty common without changing the cam or anything.

 

I have the converter, I'm just wondering if it is worth the time and trouble. I can't help but think that it is. What can I expect changing out the OEM for a 2500 stall?

 

I can't say for sure. I'm new at this too. I plan on getting a 3000 stall on a Mustang. Some even recommend a 3200 or 3500. But the interest there is the drag racing strip. I was thinking a 3000 would be a good compromise between street and strip.

The major drawback of a high stall is that it generates more heat. If you get an aftermarket transmission fluid cooler, you should be ok. At least, that's the popular recommendation on the Mustang message boards. Check out www.tccoa.com. It's a Thunderbird message board. They have very good technical information about Ford transmissions.

 

I installed a hi-stal converter to match my cam. It realy help performance, but I also lost about 3mpg. It's important to match the converter to the cam with a automatic trany.The torque output of you engine, and where its at, realy determines what gears you need to pull larger tires. with a 350ci engine the gear recomendations above are about right.My 2cents.

 

If you swap in a higher stall converter that is not matched to your cam you're going to have a lot of trouble, both with performance and mileage. More or less what you're trying to do by putting a high stall in a stock engine is equivilant to revving a stick shift and popping the clutch because you don't have enough power to get going. A gear ratio change is the way to fix this, not a high stall.

Propellerhead, 3K is a fairly high stall for a street driven rig. The problem with this is you're not going to be operating at an RPM that is at or above your stall speed most of the time. This means you're running 2500-3000 RPM ALL the time which means you create more heat, burn more fuel, put more wear on your engine, etc. I'm running a custom built 2500rpm stall in my C6 which is toward the bottom end of the spectrum for my cam's power range. It does great for what I built this truck for but on the street it creates a LOT of heat and I get about 4 mpg. I knew it was to be expected and my truck is nowhere close to stock so it's not a big deal for me, but to put that stall in a stock rig is going to create a lot of headaches. Your stall converter NEEDS to be matched to your cam. Ideally, it should also be built for your vehicle, not an off the shelf converter. My Art Carr converter was designed specifically for my truck based on cam specs, truck weight, gear ratio, tire size, etc. They punch all the info into their machine and it builds a converter to work with all the other parts on the truck. An "off the shelf" 2500rpm converter in my truck would be stalling at 3300-3500 rpm because they're typically designed for cars which are much lighter.

 

Amen to that Ivan. Thats the problem I have now with my converter, I'm always above 2000rpm around town. It kills my mileage. I have a lower stall converter for my new cam, just been lazy with putting it in.