• Welcome to the new SAOCA website. Already a member? Simply click Log In/Sign Up up and to the right and use your same username and password from the old site. If you've forgotten your password, please send an email to membership@sunbeamalpine.org for assistance.

    If you're new here, click Log In/Sign Up and enter your information. We'll approve your account as quickly as possible, typically in about 24 hours. If it takes longer, you were probably caught in our spam/scam filter.

    Enjoy.

T5 with a 1725 motor

Bill Blue

Platinum Level Sponsor
View attachment 25838 View attachment 25837 Early GM used the T5 also with a wider bolt pattern, later used the Ford pattern. The other GM RWD 5 speed was the Aisan MA5/AR5 used in Solstice and Colorado pickups. It uses the same pattern as the Toyota Supra R154 transmission.
Jim, assuming the photo on the left is the Aisan, it appears to be more compatible to an adapter. Any data, such as to size of bolt pattern and length of input shaft?
Bill
 

Mag0152

Bronze Level Sponsor
FYI
Gear Ratios

ALPINE. T5


1st. 3.12 3.35
2nd. 1.99 1.93
3rd. 1.295 1.29
4th. 1.0 1.0
5th. 0.72
 

260Alpine

Silver Level Sponsor
Bill, I think the input shaft is a little longer than the T5. There are Ford and Chevy adapters for it. Most use 3.27 or 3.31 rear with the 3.75 first. The Toyota R154 has better ratios. 3.25, 1.96, 1.31, 1.00, .75
 
Last edited:

spmdr

Diamond Level Sponsor
An R154 has BETTER ratios? Better than what?

What is the best T5 gear ratio set for an Alpine?


T5s have a mixed bag of possible ratios.

A T5 is a clear case of "You can have what you want, but you can't have everything"

...depending on what you want...or you consider as EVERYTHING...

All of the T5 ratios (including the R154), except the 2.95,

have a wider RPM drop from 1st to 2nd gear than the stock Alpine trans.

And the Alpine trans has a Painfully wide 1st to 2nd RPM drop, from a performance view.


But, a 2.95 T5 has a wider 3rd to 4th RPM drop (than a SV trans, or R154).

The 2.95 T5 with a .80 5th gear gives a progressive gear ratio drop.


However, IF you want close ratio upper gears, a T5 with a 1.29 3rd and .083 5th gives a great

couple of close ratio gears ( closer than the R154).


So with a T5, you get to chose ratios, most likely more than any other production trans!

DW
 
Last edited:

Bill Blue

Platinum Level Sponsor
The 3.75:1 1st gear ratio is totally unsuitable for a Series Alpine with a 3.89:1 or 4.22:1 rear axle ratio.

https://en.wikipedia.org/wiki/Aisin_AR_transmission
Not ideal, but definitely okay, maybe suitable. I lived with a 3.76 first gear matched with a 3.80 rear in the Durapine for many miles. Many, many drivers took a spin behind the wheel. My only restrictions were I ride shotgun and they tell me their impressions and especially, complaints as they happen. Over the years, this lead to many improvements. But to the point, not one mentioned the transmission, other than "short throw". Perhaps mine was not not a Series Alpine from a technical standpoint, but vastly increased power should have magnified this particular "problem".

I came to the conclusion that overall low gear ratio was not important if the gearbox had good ratio spacing. The important criteria is 5th overall ratio. I'll spend literally seconds in first gear, compared to hours in fifth. So I'll take a 3.75 first gear over a .65 top gear.

Bill
 

Bill Blue

Platinum Level Sponsor
Bill, I think the input shaft is a little longer than the T5. There are Ford and Chevy adapters for it. Most use 3.27 or 3.31 rear with the 3.75 first. The Toyota R154 has better ratios. 3.25, 1.96, 1.31, 1.00, .75
Just wondering, if Barry's comment about the 3.75 first gear is held to be valid, what would be a good rear end ratio to use with the .73 fifth gear AR5? .73 combined with a 3.31 yields an overall ratio of 2.41. Pretty tall for a 1725. The 3.89 gives an overall ratio of 2.84, which might work when combined with 165 X 13" tires.
Bill
 

260Alpine

Silver Level Sponsor
Bill, stock Solstice sports car with that transmission use 3.73 for turbo and 3.90 for N/A. Colorado pickups use 3.42.
 

spmdr

Diamond Level Sponsor
If we are fantasizing of other transes, how about an early Miata 6 spd:


1st-3.760

2nd-2.269

3rd-1.645

4th-1.257

5th-1.000

6th-.843

....could I live with a 3.76 first gear?

maybe not with a 4.22 rear....:)

But, You can bet your sweet bippy, if I had one, I'd work on installing it.

DW
 
Last edited:

spmdr

Diamond Level Sponsor
But, not ALL Miata 6 speeds are the same:

(no OD and what would you do with THAT first gear??)

DW

2016 and newer Miata 6 spd

Ratio

1st-5.087

2nd-2.991

3rd-2.035

4th-1.594

5th-1.286

6th-1.000
 

Bill Blue

Platinum Level Sponsor
How about a Miata five speed?
1st.-3.13
2nd.-1.88
3rd.-1.33
4th.-1.0
5th-.81
Just as good but more plentiful and cheaper. Unless your addicted to an unsatisfactory 1st gear.

5.087 low gear? Please tell us that is a typo.

Bill
 

husky drvr

Platinum Level Sponsor
from an article on differences in new 2016 MX5:

2. The Miata's manual transmission has an unusual 1:1 sixth-gear ratio

In most modern manual-transmission cars, fifth, sixth, and even seventh gears are overdrive gears, meaning the transmission's output shaft spins faster than the input shaft to lower engine speed and, hopefully, save fuel. In the Miata's 6-speed, top gear has a 1:1 ratio because the lack of a gearing change saves a minute amount of friction, improving highway fuel efficiency. As a result, all of the Miata's gearing has been adjusted to compensate: The final-drive ratio is an unusually tall 2.866:1 (versus 4.1:1 in the outgoing NC Miata) and the first-gear ratio is 5.087:1.

https://www.google.com/url?sa=t&rct...-mx-5-miata/&usg=AOvVaw0TkcNng3Agkeh0TcA4JLQ2
 

spmdr

Diamond Level Sponsor
The EARLY Miata 6 spd trans has closer gear spacing, than the 5 spd.

As a matter of fact, the 6 spd has the same gear spacing for 2nd to 3rd and 3rd to 4th

As the Tiger close ratio Ford toploader has from 1st to 2nd and 2nd to 3rd, and then

a bit closer then the Tiger 3rd to 4th.

I guess you don't HAVE to use 1st gear, of the 6 spd....


BUT, of course, HERE we are contemplating installing the T5...

DW
 

phyrman

SAOCA Secretary
Diamond Level Sponsor
Conversion Components,Ltd in New Zealand makes a conversion kit to put the Toyota box in an Alpine.
There is a great write up on the TigersEast/Alpines East web site dated 2-4-2016
The kit sans Toyota box is a bit pricey, but they have done all the work!
Something to consider.

BD
 

DanR

Diamond Level Sponsor
Something to consider.
Bruce, Some of us are well aware of that option. George Coleman did that years ago and is a satisfied customer.

I think this discussion was started in an attempt to get something a bit more economical.....
 

Bill Blue

Platinum Level Sponsor
A dab off topic, but related. I have been told by a reliable source that the Alpine pilot bearing is nearly 2 mm smaller than the .669" posted by Brian. I do not have an Alpine transmission that I can measure. Could someone verify the pilot shaft diameter?
Bill
 

Bill Blue

Platinum Level Sponsor
The Alpine pilot bearing/bushing has nominal dimensions of:

OD .875"
ID .625"
WOW! Just like I had surmised, we were mixing apple and oranges. But where in the world did the .669" come from? I think that that whenever something is posted, it should be regarded as "a version of the truth". That is definitely the case with me. It's getting to the point that I can believe nothing that I see. I play a lot of solitare on the computer. I am finding that my brain can turn a four of hearts into a Queen of Clubs, no problem.
Bill
 
Top