Transmission swap questions for 2.8

[JoshT]

Hello, I know I don't post often but I need a little guidance on this one.

The subject: 1984 Ranger listed in signature. Fresh 2.8L V6 and currently has Holley 390 cfm 4bbl with vacuum secondaries.

The goal: Street truck

Future plans: 3" drop, rear axle swap (93 & up wider axle, not necessary), and possibly slightly shorter tires (depends on space after drop)

Swap requirements: Manual transmission, short throw shifter available

Ok, the TK5 in my 84 is about worn out. To be fair it has held up well, especially since it's now 25 years old, has been through every new driver in my family since it was built, and was the vehicle for choice for the rest learning to drive a manual. With new motor and new direction for the truck it's about time for the TK5 to be retired or rebuilt. Since I can't get the short throw shifter for this trans (and parts are harder to come by) I've decided to swap to a newer Ranger transmission but I don't know which one.

What I know is that the manual trans form any 2.9 or 4.0 will bolt up to my 2.8. I know that gear ratios differed according to the engine. I think that to get the short throw shifter I have to get a M50D. I don't know what gear set would be better for a street truck. Would I be better with 2.9 or 4.0 gearing?

Really I would like to know what the best combo of transmission and rear end gears would be for a 2.8L street truck. That way I could grab both those and the speedometer gear from the same truck as a starting point.

Any help is appreaciated.

 

[martin]

I think the first gear ratio on the 4 liter gearset would be too high to be comfortable with a 2.8. but that's just my poinion. Gear ratio would depend on tyre size but I would think that 3:73 or 4.10 would work ok.

 

[JoshT]

Thanks for the reply. I'll have to do some checking into that.

One bit of info I forgot to mention in the first post is that the new engine has the stage 3 comp cam which is supposed to be a mid to high RPM range cam. I don't know how this might affect the gearing for the transmission, if at all.




EDIT:

SOB! I just found my cam card and discovered that they set me the wrong cam. I had ordered the Comp cam 30-241-4 and tey sent me the 240. So rather than the upper mid range RPM boost, and noticeable idle that I thought I was getting I got a low to mid range boost and smooth idle. I suppose that with the proper gearing the RPM range won't matter so much, but I was really wanting the idle. Guess that might also explain why I never thought I was getting the idle right.

 

[JoshT]

Well I got to playing around on the internet and found this: http://www.grimmjeeper.com/gears.html

Form the looks of it the gear ratios in the 4.0L might be better for me but I don't know if I'm reading it right. It also seems like I probably need to go to taller gear instead of a shorter one. IE: 3.27 instead of 3.73 (FYI: currently have 3.43) I'm going for a street runner/cruiser. If I were to need to pull anything I'd use the 99 with the 4.0L.

I'm confused, but I think that a 3.27 rear axle and the 4.0 gear box would be excellent for cruising, and then I could have a second axle that I could swap in if I knew I were going to be racing (aka trips to the track).

 

[Beanmachine7000]

Dropping your cruising RPM's won't do anything for you except eat up more fuel, especially if you are building up a higher hp motor... I'd go with at least 3.73's... Maybe 4.10's depending on where your peak torque comes in...

 

[JoshT]

Dropping your cruising RPM's won't do anything for you except eat up more fuel, especially if you are building up a higher hp motor... I'd go with at least 3.73's... Maybe 4.10's depending on where your peak torque comes in...

Are you sure about that first part? Comparing apples to oranges here, but... MY mothers taurus cruises at a much lower RPM and gets a lot better gas mileage than my truck. At the same time it'll haul butt if you hit the gas. Aside from the obvious aerodynamics and front wheel drive, I can't come up with any thing other than gearing that really differs. I'm probably looking at things way to simply though.

Ok this makes it sound like I really need to have the engine put on a dyno and find out just what is doing. I hate looking for answers only to wind up with more questions, but I guess that's how I learn.

 

[Beanmachine7000]

You won't lose any speed with 3.73 or 4.10 ratio (ok, truthfully you will redline sooner, but you won't be able to reach the speed you would top out with either gearset anyway)... Running your engine at it's peak torque is how you get the best gas mileage... That's where your engine is most efficient at using the available air and fuel... Loping along at 1800 RPM your engine is less efficient and more of the fuel is turned into heat instead of mechanical energy... Wherever your peak torque is (2600 RPM on a stock 2.8) is the most efficient spot to run...

 

[Beanmachine7000]

Ok this makes it sound like I really need to have the engine put on a dyno and find out just what is doing. I hate looking for answers only to wind up with more questions, but I guess that's how I learn.

It's how we all learn... I've asked my share of questions and still have plenty more...