1968 4 speed toploader = close ratio vs wide ratio

[J.Bart]

i am wondering the differences between close and wide ratio trans.
not so much in specs, but in actual use, drivability.
i have both and am not sure which one i want to use.

 

[hookedtrout]

Not sure I even know what the difference is supposed to be but I do know when I drove my brothers new Shelby you didn't have to move the shifter very far to shift gears. Not sure how to explain it but it was unreal. My 62 F100 that I just bought would be the opposite, you could hit the passenger when shifting in to reverse.

 

[J.Bart]

i have a hurst short shifter in my 08, they are cool
but the difference in the tranny's is gearing.
i'm not sure on the exact specs.
i'm more interested in the user application, how they drive.

 

[di81977]

My understanding, but I am no expert, is that you need to match it up with your rear end gears. In general, wide ratio will do better with a higher geared rear end (i.e. 2.75 or 3.00) and close ratio will do better with lower gears (3:90). Close ratio the gear spacing is closer and thus the engine RPM stays closer to the engine power range as you change gears.

You probably want to get feedback from people that have both and different rear end ratios. I suspect Wide Ratio is probably better for cruising and normal everyday driving, while close ratio would be good for the strip.

David

 

[Mosesatm]

They both drive fine. The only difference is the gearing so it all depends on how you want to drive it.

The wide ratio version has much shorter 1st and 2nd gears so it will give you better hole shots but you'll need to shift sooner into 3rd.

Wide = 2.78, 1.93, 1.36, 1.00
Close = 2.32, 1.69, 1.29, 1.00

As you can see the spacing between the gears on the wide ratio are wider than on the close ratio, hence the names.

Edit,
David is 100% correct, the close ratio transmission is excellent for racing when tied to short rear end gears.

 

[calspcl]

Hmm Arlie, the beast has a 325 rear end. I was thinking it had a close ratio top loader as I can go through the gears very quickly. It seams like 1st gear takes a lot of clutch slide to engage. BUt after I am in first its easy squzzey. The wife has commented in the past about how fast I shift though the gears.

IIRC from last summer, before it started to rain!!!!!!!! and has not stopped and I we were driving to Robs Brisket GT/CS BBQ, at 60 MPH I was turning 3K plus RPMs. It was a little too much RPMs IMO for a cruise RPM. But that was last year and the IIRC does not always work so well.

Jbart close ratio is a hoot to drive around town, If you are crusiing the hiway, I would go with the wide ratio.

 

[di81977]

Hmm Arlie, the beast has a 325 rear end. I was thinking it had a close ratio top loader as I can go through the gears very quickly. It seams like 1st gear takes a lot of clutch slide to engage. BUt after I am in first its easy squzzey. The wife has commented in the past about how fast I shift though the gears.

IIRC from last summer, before it started to rain!!!!!!!! and has not stopped and I we were driving to Robs Brisket GT/CS BBQ, at 60 MPH I was turning 3K plus RPMs. It was a little too much RPMs IMO for a cruise RPM. But that was last year and the IIRC does not always work so well.

Jbart close ratio is a hoot to drive around town, If you are crusiing the hiway, I would go with the wide ratio.

Once you are in 4th gear, close ratio and wide ratio are both the same (i.e. 1.00) and it is the rear end ratio that impacts RPM's.

60MPH turing 3K RPM does not sound like 3:25 gears. I'd say more like 3:70's. Were you in 4th gear?

 

[Mosesatm]

Using the correct diameter rear tires these should be your estimated RPMs at 60mph


2.79 = 2150
3.00 = 2320
3.25 = 2510
3.55 = 2740

Here's a formula for calculating the numbers.
RPM = MPH (Transmission Final Drive)(336)(Rear Ratio) / (Tire Diameter)

For example, on my car I'd get:
RPM = (60mph)(1)(3.00)(336) / (26.1") = 2371

There are also calculators on the web
http://www.csgnetwork.com/multirpmcalc.html
http://www.ringpinion.com/Calc_RPM.aspx
http://www.angelfire.com/space/slr/RPMCalculator.htm

I won't swear to this but I think the "5" transmission code on the data plate was for the wide-ratio toploader, and that was the only one offered on '68 Mustangs.

 

[GT/CS S Code]

Just to confirm ...

Our data plate is marked "5" for the transmission and the Marti says it is a "wide ratio" 4 speed ...

 

[CougarCJ]

I won't swear to this but I think the "5" transmission code on the data plate was for the wide-ratio toploader, and that was the only one offered on '68 Mustangs.

Correct.

The close ratio transmissions didn't come out until 1969.
1969-71 Close ratio only on the 428CJ's, Boss9's, and 429CJ's.

1969 Either close or wide could be ordered on Boss 302, 351 engines, and 390IP.
Majority of the Boss 302's were close ratio, and 351's and 390-4V majority had wide ration 4 speeds.

1970 about an the same for the Boss 302 (mostly close ratio), 351's favored the close ratio top loader by a very small margin (because of the 351C introduction?).

1971 Wide ration toploaders only available on the 351's, including the Boss 351. Final year for the close ratio, and it was only available with any of the 429CJ engines.


I own a 1969 Cougar XR7 with 428 SCJ and 4 speed transmission (close ratio). I think because of the torqueness of the big block engines at most rpms, they can better utilize the 2.32 1st gear. I can honestly say, that 1st and 4th gear see more use than the other two gears. I seldom down shift into 3rd gear during most drives.
*Note - I converted to 3.25 ring and pinion gears from the original 4.30 gears.

 

[dalorzo_f]

The close ratio transmissions didn't come out until 1969.

Have a '68 390 with VIN stamped toploader. RUG-AD. Per Kee, close ratio.

Kee lists a number of close ratio toploaders prior to '69, back to '64.

http://www.davidkeetoploaders.com/idchart1.htm

???

 

[CougarCJ]

Have a '68 390 with VIN stamped toploader. RUG-AD. Per Kee, close ratio.

Kee lists a number of close ratio toploaders prior to '69, back to '64.

http://www.davidkeetoploaders.com/idchart1.htm

???

Mustangs by the Numbers does not list a code 6 transmission in 1968.

 

[robert campbell]

Small blocks with 2.32 first gear first gear toploaders mated to 3.25 or less (3.00 or 2.79) are not very happy from a stop sign. Especially on a hill. Lower gears (3.50 or above) all are happy.

Got tall gears and a small block. 2.78 first gear top loader! Wide ratio!

Rob

 

[dalorzo_f]

Mustangs by the Numbers does not list a code 6 transmission in 1968.

Yep, but all I can say is I have an 8Rxxxxxx correct VIN stamped apparently factory original tagged RUG-AD close ratio in my 68 (hard to believe somone would fake that back in the 80's, the car sat that long before I bought and restored it). And Kee (and many other references) list a lot of pre-69 close ratios, so they did exist prior to '69, and both the close and wide ratios are noted in many references for '68 390's.

Never looked at it before, but the '68 shop manual lists both close and wide ratios, but a -J2 and -M2 for a 390, not the -AD Kee and some others note.

Be interesting to see some build sheets as it seems there's a variation in what is "correct" based on the sources...

 

[calspcl]

My marti has a 5 wide ratio - I will have to get the car on the lift and see what tranny is in there. Both the tranny and engine have been replaced in a former life. That said, it could be anything, I do know its a top loader at least.

 

[Mosesatm]

It's possible that in '68 all Mustang 4-speed toploaders were coded with a 5, then in '69 they started using a 6 code to differentiate them

 

[dalorzo_f]

Bingo! :smile:

I contacted Kevin about this apparent discrepancy, his reply:

"No, I can't explain it. It would appear that Ford just put the transmission code of 5 on all 68 390 cars on the data plate and did not create a distinction for that year,though the -M2 and -AD transmissions were both installed in the vehicles. Shop manuals are not a reliable source for data as they are printed before vehicles go into production."

My query was in specific relation to my -AD close ratio 390, and the fact an -M2 and -J2 are called out in the SM.

I guess one could assume the same occured for small blocks as well. Also, if you note the Marti reports they do not specify close or wide, just "4 speed manual transmission" (at least on mine).

Interesting to know how the line knew which to install, I'm guessing build sheet, would be interested to know but as San Jose removed them most of the time I don't have one for my car..

 

[Mosesatm]

It had to be based on either the engine code or the differential code, or maybe a combination of both.

 

[dalorzo_f]

390 with a 3.25 open rear got a close...