Gears for 5.0 with T-5 Trans?

What is the best gear ratio in a 8.8 to run in my 1948 ford F-1? I am installing a 5.0 motor with T-5 ford Trans. My Choices are 3.27, 3.55,3.73,4.10..Need some help...Thanks, Scot

 

well, late 80's mustangs had a 5.0 with a T5 and 3.73 posi...if that helps. Probably real nice all around ride plus highway speeds.
Id go 4.10 if you wanna hammer it between stop lights

 

Your tire diameter and engine do play a roll in this. That said I would choose a 3.73:1, which would give you low highway RPM's and good get up and go.

Another thing to try is look for an engine speed calculator on line and plug in your tire diameter and gear ratio to determine engine speed at various MPH's. If you know the torque your engine is putting out at a given RPM then you can match that with rear axle ratios to get the best combo for your engine.

 

Most guys I know that have done a similar swap use either the 3.73 or 4.10 gear as most are running a 26 or 27" tall tire.One friend running a 27" tire and 3.55s says 5th is almost useless until 75+ mph!! If the avatar photo is your F-1,it has some TALL rear tires,not a bad thing though!!! ROY.

 

I have owned a bunch of 5.0 mustangs over the years.... hell I still have one. From factory most had 3.08 gears ... for nice all around gear go 3.55. 3.73 for more performance 4.10 if you ar not worried about the mileage and at 70 mph you are going to be close to 3k rpm. This is all with 26 in tire also.

 

With a thirty inch tire, 4.10 won't be too steep.

 

What rpm on the Highway will it be when doing about 60?

 

not sure what the overdrive ratio is in a T-5 vs and AOD, but with my AOD, I ran 235/75-15 tires and a 3.80 ratio (8 inch) and was at 2200 rpm at 70

 

I have no intention of running the tires that are on it in my Avatar. I bought 17 inch Boyd Coddingtons Junk Yard Dog Rims....Not sure what to go with on tires yet though. I appreciate your feed back...Thanks, Scot

 

Here ya go!

http://www.corral.net/tech/gearcalc.html

 

Thanks Slick

 

Good rule of thumb: If the tire size and the gear ratio are the same, the rpm at 60 is about 2000; rpm at 90 is 3000. I.e., thirty inch tire, 3.00 gear.

Not sure which T5 you have, but with an OD ratio of, say, 0.70, a 4.10 rear results in about a 2.87 top gear ratio. That will be a nice fit with a 28-30 inch tire.

 

Is there a inspection tag to look on the T-5 to get the specs?

 

Without tire diameter, you cannot calculate anything. You need to know this before you decide on gears.

AnimalAin - To clarify, your first sentence you meant without Overdrive!

If it's the T-5 that came behind a 5.0, then it's almost guaranteed to be a .68 5th gear.

 

There should be a steel tag bolted to the case near the tailhousing. With those numbers you should be able to find out what it was in and gear ratios. Also, there is a thread in the tech archives about T-5's that has links to numerous websites to help you identify what you have.

 

The serial number from Borg Warner will be 1352-11-( a three digit number) But like I said above if it was a factory 5.0 (not an aftermarket replacement trans, or from a 2.3 or 3.8) it will certainly have a .68 5th gear.

 

Most 5.0 Ford T5s have a .68 overdrive, I believe. When you figure out your tire size, that would give you a good basis to choose gears.

Personally, I'd go with 3.73s if you have approx. 28" dia. or less tire. 28" dia. or more, go with 4.10s.

I'm running a 302/T5 in my Roadster --- 31" tall tires, 4.11 gears in a 9". Like AnimalAin pointed out, that 5th gear OD ratio helps out a ton if you want to run 4.10s.


Malcolm



Edit: looks like "hotroddon" posted some of the same info at the same time!

 

My Tag Number is 13-52-199. I took it out of a 91 fox body mustang. Had a 5.0 motor.

 

I am running 275-60-15 tires (28.75") on my '58 Apache with 3.73 gears behind a T-5. At 70 mph I run about 1900-2000 rpm which is a little below where my cam comes in. If I run 75-80 everything is good but at 70 I have to drop to 4th on grades sometimes. I have a 283 in the truck.

 

I ran and was and am still very happy with 3:73.... 4 :10s are to steep on average for daily driving unless your tire size is over 32.

If you dont plan on driving it on the freeway, and your truck is over 5000 lbs then perhaps 4:10, but I still wouldnt. Keep in mind, depending on what T-5 your first gear is already low, or high.

 

Your ratios are 3.35/1.99/1.34/1.00/0.68. Period. That's what they were in 1987-1993. All T5 were virtually identical and only had minor differences. The '93 COBRA had slightly different ratios I think, but in '91 you only got the ratios listed above. The AOD, for comparisons sake, has 2.40/1.46/1.00/0.67 ratios. All of them were the same until the AOD/E-W (later renamed 4R70W) came along in 1994. It has 2.84/1.68/1.00/0.70 ratios and is computer controlled. You can, however, put the gear set from the 4R70W into the older AOD.

I run a 1990 Mustang GT 5.0/T5 with 26" tires and 3.73's. It turns ~2400 at 72 mph. First gear is pretty steep. I love the car, but I am trying to sell it so I can get something older and cooler.

Make sure you buy a good aftermarket shifter with positive stops. It will prevent you from over shifting and damaging the shift forks.

Really need to know what size rear tire you plan on running.

Also if you are buying new gears, buy Ford Racing gears. Ford level of quality is well beyond any aftermarket companies.

 

Agreed. I am running 820-15's (29.5 diameter) in my RPU and 4.11 gears in the 9" rear. Motor is a '85 5.0 HO sbf and the trans. is a 4 speed SROD.

The 4.11 rear gear is "just right".

So true. Many folks underestimate how tire diameter affects rpm.

 

I love 373s I've had them in three cars with 302 t5 8.8 setups. Perfect for the street strip set up. And is averaging 75 at 2300-2500 rpm in fifth gear.