Transmission shift points

Roger Harmon
Roger Harmon Expert Adviser
edited November -1 in HUDSON
Good Morning,

I'm driving the Wasp to work this week. It seems to me that the trans is up-shifting too soon; After a complete stop, I'm in third gear by the time I'm through the intersection. I really gotta mash the throttle to get it to come out of fourth after slowing for a curve or corner too. Is there a chart that shows the correct rpm or road speed for shift points? If so, how do I make the adjustment? Thanks.

R/ Roger.

Comments

  • Park_W
    Park_W Senior Contributor
    Roger, it sounds like you may simply need to shorten the throttle link to the transmission a little, to get the upshift moved up. The adjustment is very sensitive. Find the clevis adjustment on the throttle link and turn it just one turn clockwise and check the result. Then proceed a half-turn at a time. If this problem happened abruptly, the link may have gotten disconnected!
  • onerare39
    onerare39 Expert Adviser, Member
    edited November 2010
    Roger,

    If you have a Borg-Warner Transmission (as I do) the shift points are as follows. This information is straight out of the Hudson Automatic Transmission Service Manual.

    Light Throttle Upshift, 1 to 2 10-12 mph, 2 to 3 22-24 mph
    Full Throttle Upshift (at the detent), 1 to 2 31-34 mph, 2 to 3 48-52 mph
    Full Throttle Upshift (through the detent), 1 to 2 43-48 mph, 2 to 3 70-75 mph
    (through the detent = full kickdown position)

    The Service Manual has all the information you need to service and adjust a Borg Warner Transmission

    Hope this helps
    John
  • Lee ODell
    Lee ODell Senior Contributor
    edited November 2010
    In the 1951 Mechanical Procedures Manual the Hydra-Matic shift points in M.P.H. are

    MINIMUM THROTTLE

    Shift 1-2, 4-8 MPH
    Shift 2-3, 10-14 MPH
    Shift 3-4. 15-20 MPH

    FULL THROTTLE

    Shift 1-2, 10-15 MPH
    Shift 2-3, 27-35 MPH
    Shift 3-4, 58-66 MPH

    I experience the same quick shifting with my 52 Hornet. Maybe getting into hi gear sooner improves gas mileage. I like that thought, with gas prices rising.

    Have a good day
    Lee O'Dell
  • Roger Harmon
    Roger Harmon Expert Adviser
    Gentlemen,

    On the 30 mile trip in to work today, my shift points were almost dead-on to the speeds listed in this string. I guess it REQUIRES no attention,...but what if I changed the adjustment so it shifted like a TH350 (a little later at higher rpm)? Would doing so damage my transmission?
    R/ Roger.
  • Lee ODell
    Lee ODell Senior Contributor
    Roger, even if you can get it to shift at a higher RPM, the speed at the shift point 1-2, will still be way below the 1-2 shift point in Turbo 350.

    There is a hugh, first gear ratio difference between the two. I believe Hydro has 3.15 first gear compared with Turbo 350's 2.51 first gear. The Hydro's second gear is probably closer to first gear in a Turbo 350. So the Hydro will alway shift sooner than a 350.

    Dany Spring at KGAP makes a real nice adaptor kit to instal a turbo 350 behind a Hudson engine. That will give you the shift experience desired.

    If my hydro ever bits the dust I'll get the adaptor kit to instal a 700R or 200R. But then I would probably have to change rear gears to 4.11 to keep from lugging the engine on the hi way. One change alway requires other changes. Oh well.

    I'm glad to read you are driving the Hudson daily. You must be getting alot of attention with it. Let us know what you do and how it turns out.

    Lee O'Dell
  • Park_W
    Park_W Senior Contributor
    Lee, in comparing shift points between a Hydramatic and Turbo 350, don't forget that the Turbo has a torque converter up front, while the Hydra doesn't. The torque converter is acting like another gear reduction step, so that'll make the differences somewhat less than if otherwise.
  • Lee ODell
    Lee ODell Senior Contributor
    edited November 2010
    Park W wrote:
    Lee, in comparing shift points between a Hydramatic and Turbo 350, don't forget that the Turbo has a torque converter up front, while the Hydra doesn't. The torque converter is acting like another gear reduction step, so that'll make the differences somewhat less than if otherwise.

    Park, I am aware the turbo has a torque converter. As I understand, the purpose of the torque converter, is to multiply the torque output of the engine at take of from a start. Therfore, not requiring a low gear ratio as a hydro.

    I may be wrong, but I do not think the torque converter changes the gear ratio of first gear but only multipies torque output of the engine, which gives more torque to move the car at take off.

    If the engine is turning 2500 RPM in low gear, the hyro car will not go as fast as the turbo car at the same RPM.

    I think we probably have the same understanding, just worded differently. Is that righ? Or am I missing something?

    Your explantion of trans adjustment is informative. May have to try that sometime. Right now my trans is working ok. I'll keep a copy with my records.

    Thanks for the information.

    Lee O'Dell
  • Park_W
    Park_W Senior Contributor
    edited November 2010
    Lee,

    At 2500 rpm and under light load, both the torque converter and the fluid coupling of a Hydramatic are going to be essentially a 1:1 connection. Under load, I think the torque converter will "slip" more than the fluid coupling, so the torque converter car will be running somewhat slower (assuming they both have the same gear ratios behind the converter or coupling). Really, the difference in performance occurs at a lower rpm, so 2500 isn't a good speed at which to make the comparison. Here's a simple test: Two cars, one with Hydramatic, the other with a torque converter and "whatever" behind it. On both cars, hold the brakes and floor the throttle. I believe the engine on the torque converter car is going to run faster. More "slippage," which allows the engine to turn faster, which generates more power. That's one reason why the torque is increased with the converter. If that weren't the case, the early Powerglides and Dynaflows would never have been feasible, having no gear reduction at all behind the converter. All the "gear reduction" was done by the torque converter.
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