6sally6 wrote:

Alessandro wrote:

Hello Folks !  
need advice from those who have t5z trans and 3.50 rear . Now i ride 3.80 but is too short specially first and second gear .( 2.95 : 1 first 1.94: 1 second ) Absolutely needs get longer . Now are really short and seems to drive a 4x4 with reduced gear to climb hill ..... What should i look for , before buy new ring and pinion ?    3.50 /3.40 / 3.27 / 3.00. thanks !

I like 3.40 if the engine is mostly stock (230-250 HP)
3.27 if its stronger.
I know....backward for a drag racing point of view but.......for spirited street driving(and autostonda) get the 'longer legs' of the 3.27
6sally6
 

I agree.  3.27's will work fine - 3.40s  will work too, but might be a little long.  If you are just canyon carving in the Apanines,  you will be happy with the 3.27's.  Put it in second or third and wail around those curves!

6sally6 wrote:

Alessandro wrote:

Hello Folks !  
need advice from those who have t5z trans and 3.50 rear . Now i ride 3.80 but is too short specially first and second gear .( 2.95 : 1 first 1.94: 1 second ) Absolutely needs get longer . Now are really short and seems to drive a 4x4 with reduced gear to climb hill ..... What should i look for , before buy new ring and pinion ?    3.50 /3.40 / 3.27 / 3.00. thanks !

I like 3.40 if the engine is mostly stock (230-250 HP)
3.27 if its stronger.
I know....backward for a drag racing point of view but.......for spirited street driving(and autostonda) get the 'longer legs' of the 3.27
6sally6
 

Thanks 6sally6  that's what i wanna hear !  . I have think about it and more or less i was around 3.50 /.3.40/ 3.27 . 
now i am more sure about it leaving the 3.50 . i think i will go for 3.27 .

ciao ! 

Hi Alessandro-

My trans has a 2.95 1st and I went with a 3.5 rear gear ratio, which should be a good compromise in terms of off the line aceration and 5th gear highway cruising.

When picking your rear gear ratio, there are a number of factors you need to consider which include your camshaft and what RPM range your cam is most efficient in, your 5th gear ratio (which in the T5-z is 0.63:1) and your rear tire size.

You should input the details for your car into the below calculator using each of your transmission gear ratios from 1st - 5th, your rear tire size and then run the calculations which each of the different rear gear ratios you are considering and see what RPM your engine is turning in with each rear gear ratio and what the corresponding miles or kilometers per hour works out to.

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

Using my tire size (245/45/17, which is 25.68" tall) at 3500 rpm in 1st gear, the car is going 26 mph. But at 2000 RPM the car is doing 70 mph.  Depending on your cam, I don't think you to go much lower (numerically)  a 3.5 or your engine won't be turning enough RPM and will be lugging in 5th gear.

Thanks Alessandro!

This question helps me out too.
Appreciate it guys!

Rufus68 wrote:

You have the advantage in this situation to have your own personal experience.  You have the transmission with your current 3.80 gear set.  And you know this gear set is lower than you want it to be.  Look at your choices: 
As an example, say you're currently turning 2500 rpm at 70 mph
3.50  is 92% of your current RPMs;   70 mph would be 2300 rpm
3.40 is 89% of your current RPMs;    70 mph would be 2225 rpm
3.27 is 86% of your current RPMs;    70 mph would be 2150 rpm
3.00 is 79% of your current RPMs;    70 mph would be 1975 rpm
You can plug in your correct RPM you have at 70 mph.  But going by the example, I would want either the 3.00 or the 3.27 because I would want my cruise RPM around 2000.

My thoughts exactly.  I have a 3.00 rear gear and run right about 2,000 at 70mph.  That is perfect for me.  When I had the top loader, I always felt like I needed another gear.  And, with that 3.35 first gear, I still have to shift earlier than I want.  I can't imagine what it would be like with a 3.50 or higher rear end.
 

Just keep this in mind.  Regardless of your choice, you will still quietly wonder what it would have been like with the various other ratios.  I run 289, close to stock 260 hp, 3.25 single track with 92 model T-5.  Hits hard and gets mid 20's highway mileage.  You gonna race, then 3.40-3.80.  All out racing, 3.90-4.11.  The larger the ratio, the more unnecessary the first gear or two in the tranny.  Lotsa choices.
Best
Al

All the gears work together in driving the car.  It is equally foolish to choose a rear gear ratio that would cause 5th gear in the transmission to slow the rpms of the engine too slow at normal cruising speed to be usable; just as it would be foolish to choose a rear gear ratio that would cause 1st gear in the transmission to speed up the rpms of the engine too much to be usable as well.  Either of these rear gear ratios cause a 5 speed transmission to behave like a 4 speed transmission.  One should match the rear gear ratio to the transmission gears and rear tire diameter such that 1st gear in the transmission performs its duty of starting the car off and 5th gear in the transmission performs its duty of comfortably driving the car along at cruising speed.  Any other choice is just a waste.

Whew, I feel better.  I'm sorry you read this if what I've said bothers you.

I have a T5Z with a 3.25 gear and like it a lot.   Seems to cruise nice at 65 in 5th gear. Take off is pretty good. It is single spin though.  Like to do a true track or something like that down the road.  Id probably used the same gear ratio. 

Nos681 wrote:

Thanks Alessandro!

This question helps me out too.
Appreciate it guys!

You are welcome !  this thing about rear gear is something that i want to solve since last year . 
Probably was better  compare the trans gearing from a car with t5z and see what axle ratio was using and start from there my thought .  In that situation probably i had choose 3.27 earlyer  . 
Anyway i want to listen some advice that rise axle ratio to 3.40  - 

Now is only a question of choice :  3.27  or 3.40    let me know yours and why  . 

bye ! 

Chaplin wrote:

Hi Alessandro-

My trans has a 2.95 1st and I went with a 3.5 rear gear ratio, which should be a good compromise in terms of off the line aceration and 5th gear highway cruising.

When picking your rear gear ratio, there are a number of factors you need to consider which include your camshaft and what RPM range your cam is most efficient in, your 5th gear ratio (which in the T5-z is 0.63:1) and your rear tire size.

You should input the details for your car into the below calculator using each of your transmission gear ratios from 1st - 5th, your rear tire size and then run the calculations which each of the different rear gear ratios you are considering and see what RPM your engine is turning in with each rear gear ratio and what the corresponding miles or kilometers per hour works out to.

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

Using my tire size (245/45/17, which is 25.68" tall) at 3500 rpm in 1st gear, the car is going 26 mph. But at 2000 RPM the car is doing 70 mph. Depending on your cam, I don't think you to go much lower (numerically) a 3.5 or your engine won't be turning enough RPM and will be lugging in 5th gear.

Alessandro, this is great information.

What is your rear tire size? The tire height plays a role in deterring all of this.  
What is your 5th gear ratio.

I understand you don't want a 4x4 for starting from a dead stop. On the other hand, you don't want to give up so much gear that you are constantly slipping the clutch to get moving. Some guys will use a 10:1 ratio as a guide line to help determine a rear gear size. Multiple the first gear ratio by the rear gear ratio for a value. 3.8 X 2.95 is 11.21. For 3.27 gears, its 9.64. For 3.40 gears, its 10.03. For a 3.50 gear set, its 10.325.

What is your typical cruising speed?
Where does your engine make power now? 
How long till your cam upgrade and where will the power band shift to then in the RPM range?

Based on the information you provided, I would stick with a 3.40 or 3.50 gear. If your tires are overly short or tall, the gear set could change.


 
 

Bolted to Floor wrote:

Chaplin wrote:

Hi Alessandro-

My trans has a 2.95 1st and I went with a 3.5 rear gear ratio, which should be a good compromise in terms of off the line aceration and 5th gear highway cruising.

When picking your rear gear ratio, there are a number of factors you need to consider which include your camshaft and what RPM range your cam is most efficient in, your 5th gear ratio (which in the T5-z is 0.63:1) and your rear tire size.

You should input the details for your car into the below calculator using each of your transmission gear ratios from 1st - 5th, your rear tire size and then run the calculations which each of the different rear gear ratios you are considering and see what RPM your engine is turning in with each rear gear ratio and what the corresponding miles or kilometers per hour works out to.

https://spicerparts.com/calculators/transmission-ratio-rpm-calculator

Using my tire size (245/45/17, which is 25.68" tall) at 3500 rpm in 1st gear, the car is going 26 mph. But at 2000 RPM the car is doing 70 mph. Depending on your cam, I don't think you to go much lower (numerically) a 3.5 or your engine won't be turning enough RPM and will be lugging in 5th gear.

Alessandro, this is great information.

What is your rear tire size? The tire height plays a role in deterring all of this.  
What is your 5th gear ratio.

I understand you don't want a 4x4 for starting from a dead stop. On the other hand, you don't want to give up so much gear that you are constantly slipping the clutch to get moving. Some guys will use a 10:1 ratio as a guide line to help determine a rear gear size. Multiple the first gear ratio by the rear gear ratio for a value. 3.8 X 2.95 is 11.21. For 3.27 gears, its 9.64. For 3.40 gears, its 10.03. For a 3.50 gear set, its 10.325.

What is your typical cruising speed?
Where does your engine make power now? 
How long till your cam upgrade and where will the power band shift to then in the RPM range?

Based on the information you provided, I would stick with a 3.40 or 3.50 gear. If your tires are overly short or tall, the gear set could change.


 
 

Thanks for this info , i have 205/70/14 ( 25.3 tall )  tire  and now my cams are original 289 engine and i believe they are in cam zone from 2700 and 3000  , but i am not sure about it . never try to take note .  
What i can say is top speed at 90 /100mph at 4000 , more or less . 
About cams upgrade i think next year winter project  . so i got 1 year to use a 3.40 or 3.25 .
My highway speed is 80/93 mph so little speedy  when i can ,  average is 85  . Now to stay at 75 mph i am at 2500
What i really hate is first and second gear , the rest more or less are  right . 
3rd 4rt 5th  are the gears where engine gives more satisfaction for torque and top end . 
At the end every suggestion is correct  3.40 could be acceptable between 3.25 and 3.50   . 
thanks 
 

OK, I may be a convert now on gear ratio...
My 66 has a 427 and TKO 600 and 3.70 gears.  I love the way the gears feel when accelerating.  They give a much more powerful feel than the 3.50's I used to have behind the 400HP Windsor.  BUT, I am finally getting tired of being blown off by every Honda and Kia at stoplights. (unless I really push the loud pedal real hard).
It seems I am busy building RPM very quickly in 1st gear, but not really going anywhere, while I watch them accelerate into the distance.  I have decided to go back to a 3.50:1 ratio gear in my car.  I guess I am just getting old...