From his comments, I take it to mean he wouldn't want any higher of a ratio, which would be lower numerically, and would totally make sense.

 

I was quite surprised when it came out to be 2.75. Even with that high (or numerically low) ratio I rarely start in 1st. I can't imagine if it still had the original rear/gears in it how it would be. A heck of a work horse it was!

What I don't fully understand is how the ratio in the tranny comes into play. I assume it's measured on the same scale as the rear end (numerically higher means a lower ratio). If that's the case than if I got with the earlier s10 trans with the lower gearing, I wouldn't want to go too low (or numerically high) on the rear? Or am I off base.

 

Mine's a Dana 60 47/12 (about 3.90), 364 c.i. Nailhead, needs the Z-specs I think.

 

Identification Key to Borg-Warner T5 transmission ID Tags
Identifying and Assembling a T5 5 Speed


Those are 2 of the best T5 Identification links, I would advise printing the 1st out and taking it with you to help ID.


I am running the following combination:


28" Tires
2.75 Rear
3.35 1st, .68 OD
That is all behind a 300 six.


I think most of the post on here about not getting into 5th gear are flat out WRONG! For the simple fact that you are running an inline 6 which starts producing its torque at a much lower rpm than the V8 comparisons.


Now as far as the flatty goes you are going to have to do some research involving the torque curve, on your cam as well....... so start with the cam, figure out at what rpm the torque is sufficient enough to pull the truck down the road and go from there. That's where you need to listen to the guys here running flatties.


Your launch ratio will be about 10.8, based off of a 4.03 1st gear.

 

No doubt oneye, you'll need the Zspec more than I ever will in Old George. Maybe someday I'll have something with a little more umph, but that'll have to wait until the kids are out of the house...... Looks like you have a car business of your own based off your advertisement on your truck. She looks good!

Thanks for the info Clintonvillian! The other charts I've see you have to type in your number and it spits out what you have, making it impossible to print out. This one I can take with me and save some time. So your 2.75 gears don't kill you off the start with the 3.35 first? My novice mind told me it wouldn't get out of it's own way for the first couple of gears (or would it be the opposite???), but it's good to hear from someone that's running them in their rig. As for the flatty, I may have to adjust my rear after I install it. Since I don't plan on dropping it in for a few years, it sounds like I should match the rear to my 226 and whatever T5 I end up with now.

 

Right. It takes HP to go down the road, and up hills. The sweet spot for economy for a flathead is around 2000 - 2200. If you work backwards from there, with 28" tires, .72 5th gear*, aim for 60 mph, you get very close to stock 3.92 gearing. With a 3.25, you'd be at 1,700 RPM, way down the curve. With a 3.00 you'd be at 1500. The guys with flatties in '32 roadsters can pull that kind of gear, a truck pushing a barn door thru the air will be in and out of 5th on any kind of hill.

* S-10 T5's have 5th gear ratios of .72 - .86, the Mustang types are the lower .68. Good list here: The T5 page

They are definitely not all the same!

 

sere - My T5 came from a 86 S10 V6 and has 3.76-2.18-1.42-1-.72 gear ratio. My flattie is a bored and stroked 286ci - That and the 3.25 rear ratio makes the 39 fly. Ken

 

Ross, is the 2000-2200 the best range for the 6 and 8? Also, do you have some sort of calculator for all this, or are you just that smart? Thanks,

Ken, great info, thank you.

 

I have to correct Ross's statement. HP doesn't move a vehicle the torque does!


HP vs TQ curves will be completely different between the I6's and the V8's.


A 6 will start building torque off of idle and typically kind of level off by 2000 rpm (so between 1500-4000) you have consistant torque. HP on an inline six is not often of concern.


A V8 is much different. It will typically start building torque at higher rpms, say 2000 then peak at 4-5000, with a much smaller flat line. Horsepower tends to be higher than that of I6's but all is done at higher rpms.


Again, all of that info is engine specific and greatly varied by cam choice. you can push the peaks up and down all depending on the cam profile.


I think you will be fine with 2.75's in the 6, but I think once the flattie goes in you will want a bit more when you get into 4th and 5th gears. It will be really hard to get an overall combo that suits both engines, they are just to different.

 

I don't have HP-torque curves for the 8BA (I don't think they were published) or for the 226, but I do for the very similar 59A series V8. It shows torque and efficiency peaking between 1500 and 2500 RPM. But HP is nearly linear in this region, and that is what you need to look at. At 1500 HP is only 43, at 2000 is 66, at 2500 it's 78. These are all at WOT, not where you want to be for economy. You want to be spinning enough to generate enough HP for whatever cruise speed you desire without having your foot in it, which pops the power valve open and destroys mileage.

With a 5-sp, you can obviously drop down a gear and maintain your speed by kicking RPM up; with a 3-sp, not so much. At 60 mph in 2nd with a 3.50 axle, you'd be at 4100. With a 5-sp, and 3.92 axle, you'd be at 2800.

I've read literally thousands of first-hand reports from people who have every conceivable combination of gears and tire size, in every kind of flathead-powered vehicle. Also considering high and low altitude, weight of the vehicle, aerodynamics (trucks vs cars), etc. Also gearing of the flat-powered Ford cars that came with factory OD's. The common thing with respect to stock motored, stock height (F-1) trucks is to be at around 2000 - 2200 at 60 mph.

My personal metrics are MTFlat and Tinman. MT has a stock motor, stock truck with a 3-sp and runs a 3.50 rear, lives at my altitude (mile high) and also has to deal with mountains. Tinman has a 5-sp, some engine mods, is lowered a little (helps aero), he's also at high altitude and has mountains. I would pick a proven combination used by someone in circumstances similar to yours and based on your configuration.

 

You would think I did have a vintage car business by the looks of the vehicles around my place, but no, that's the way I got the truck, and Mr. Parker did such a beautiful job of putting it together (in the 60's), I really hate to modify it ... have spent most of my effort restoring what he did, after it suffered such a long rest stop since his passing. As for the colors, it's a little too candy for me ... I'd rather have black fenders and that Forest Green color for the rest, if it were my choice. But I'm going to keep it/restore it as it is, except for removing the excessive bling, all of which I've kept intact (if whoever gets it after me would want to put it back in its 'show' condition with all the bells and whistles ... actually sirens and air horns that were on the cab). I guess you would say, so the original restoration would be note-for-note restorable. That said, an exception being the T-5 swap, which I justify as an improvement anyone would want over the current crash-box. Same for the shoulder belts going in next. I will be losing the bed upper panels (but saving them along with the rest of the bling), replacing them with stake-body-like boarding, to about the same height. Have some gorgeous inch-thick flame cherry cut for that, will take it on when the weather clears.

 

Here is a 240 dyno run, these numbers are way above your current 6, however the torque/hp curves will still look the same.


It is a good comparison so you can see the difference between the 6-8 that ross has shown above. Notice how both the v8's hp and tq peaks, in comparison the tq in the 6 rises and stays constant. Us 6 guys are all about the torque.

 

BTW, Ross........... I am not arguing with you so don't take that way. In my experience, you can run much lower ratios with I6 throughout all the gears. Not so for a V8.


We had two F250's. One a 4.9, the other a 5.7. There is no question the 5.7 had more power, but the 6 would pull from the get go. You could literally idle that truck around in 3rd and 4th gear.

 

So the pic's ain't telling the story. At least not to me yet.
In your avatar I don't see the side boards or brush guard
I see in the side/rear shot. So I guess I am asking for a lot
more pic's and info as to what they are. Like is it like that
know? Or like that when you got it? And didn't you say that
she has a nail head in it? Would love to see that. I realize
posting pic's can be a pain but once you find your "groove"
in doing it than it's not so bad.

I see your truck as awesome. But really would like to see
more of her.

Sorry Sere. I just realized I am trying to steal your thread.
Sorry.

 

Artic Y Block Agreed this is getting too far away from T-5 gear ratios. Here's a link to more pictures on my website -- I think all of these are how it was when I first got it. Only have one of the way it is now, the avatar. The stake sides are a plan for this Spring. 2002 Buick LeSabre