1957 Cadillac Transmission 4TH gear ????

[Bill Balkie 24172]

Hello
I was checking out the lastest talk on the site when this subject caught my attention . i have a 57 cadillac that runs very well . But i can not feel the transmission shifting into 4th .
How can i be sure it is in 4th ? The reason i ask is because when i an cruising  at about  60 mph The rpm's seem to be a little high, I do not have a tac in the car , it just feels like i need another gear .  . Is it passable that the shifting is so smooth you can not feel it. Maybe i should hook up  a tac ? Does anybody out there know what rpm the 365 engine should be running at in 4th gear ?
Thanks Bill

[Art Woody]

Just pull it down into third gear and see if it shifts down.

[Bill Balkie 24172]

Thanks Art ,
  That is a simple check , should of thought of that myself . still would like to know the RPM in frouth gear .


  Bill

[Dan LeBlanc]

According to the 1962 manual, the 3-4 shift point occurs at 1270RPM at minimum throttle and 4170RPM at wide open throttle.  Not sure if the 57 is the same or not, but should be close for reference sake.

[Philippe M. Ruel]

rpm in 4th gear does not depend on engine displacement, but on final (4th) gear ratio (which is almost always 1:1 on these old cars), rear drive ratio (the "economical" 3.07:1 on most 1957 models, although some feature the optional 3.36:1 ratio in standard, there was even a 3.77:1 optional ratio on Series 75) and tire size (8.20x15 on Eldorado and Series 75, 8.00x15 on others, provided your car features original size tires).

With the data on YOUR car, you can calculate the desired rpm :

rpm at 60 mph = number of inches in one mile x 60 (mph)/ 60 (minutes in one hour) / tire circumference in inches / rear drive ratio.

At 60 mph in 3rd gear, your engine must be suffering a lot. If you don't feel 3 shiftings (1-2, then 2-3, then 3-4), most probably the one you miss is 1-2, which occurs at very low speed.

[Bill Balkie 24172]

Thanks Phillippe ,
   It is more complex then just speed and rpm 's there is alot of factors to consider . I think i will take Art's advice on the downshifting to third and see if i feel the shift from 4th to 3rd . If i do not , then i will realling be asking some questions .  I feel very fortunete to have this great old car . I do not feel comfotable taking this car to a trans shop . Unless someone could recommend someone in the South Jersey / Philadelpia area .
and then again this might be all in my head . The trans could be perfectly fine . It just seems like it could go for another shift .

Thanks Again ,
     Bill

[Dan LeBlanc]

If it doesn't shift down and you find indeed that you have no 4th gear, you may first want to start by adjusting the TV linkage as outlined in the shop manual. 

[JKF]

I had the same doubts with my transmission, never really noticed the shiftings from 1-2 or 3-4. So I tested my car by shifting from Dr3 to Dr4 around 30 mph and noticed the shift. But revs are higher than they could be, duals comes with a price.
On these trannies (CE 57) it is normal to have the 3-4 shift as early as 17mph. 4-3 at 12 mph. Even earlier if your tires are of lower profile than when new.
A tach would be interesting if not just to know rpm at highway speeds but also to be sure that it holds 4th gear as it should. TV linkage adjustment as Dan and many others mention on this forum is very important for proper shifting.

JKF

[Bill Balkie 24172]

Thanks for all the imput . Went for a drive last night and the car did downshift when cruising at 60 mph , my shift indicater has 3 setting   low first gear ( L )  and two drive settings  (D---D).. My question is .... if the trans is a 4 speed ,should i have 3 drive settings and one low . Or can you only select 3 out of the 4 gears .

Thanks ,
      Bill

[Roger Zimmermann]

On these Hydramatic, there is no provision to have the first gear. This gear is very short; it's here to just let move the car. Max. speed in first gear is about 22 miles/h at full throttle.
Roger

[Bill Balkie 24172]

Roger,
If i understand you correctly when the selector is in low  that is actually 2nd gear

[Roger Zimmermann]

Exactly, Bill!

Roger

[Bill Balkie 24172]

Hello Roger,
  You are a tremendous asset to the Cadillac  La SaLLE CLUB .  Always polite and willing to help other owners . You have helped me in the past and your advice was always correct . Thanks Again Bill

[Roger Zimmermann]

Thank you for the flowers Bill! Other people in this forum know the matter very well; all together we try to help those who need it.
It happens also that my comments don't please everybody!

Take care,

Roger