Christmas time

Discussion in 'Discussion Forum' started by Yves, Dec 8, 2018.

  1. Yves

    Yves True Classic

    Finally I just pull the trigger for the extremely rare Ring and Pinion 17/61 3.58 from Fiat Strada available at MWB.
    I allready have a 5 speeds trany spare in my basement. That will be my Christmas gift for my winter project.

    I wish that will be a fair combo with 1500 engine with MWB performance head, D223 Cam and lightened flywheel, already operational for more then 3 years.

    My objective is to have my X to be highway pleasure trip and less noisy at 75mph.

    If i'm not satisfy after the next summer season I will put back my original trany.
    I hope I will not regret it!
     
    Last edited: Dec 8, 2018
    Brayden_connolly likes this.
  2. JimD

    JimD Waiting for Godot... Moderator

    Location:
    Missouri, USA
    I hope it works out for you Yves. I need some elves to stop by my garage and do all the little Fiat projects before spring. I am not in the mood this year. :)
     
    Peter Cecil likes this.
  3. Rodger

    Rodger True Classic

    Location:
    Olympia, WA
    I also have the MWB performance head and cam on my '79 and switched to the Strada ring and pinion. I find it much more relaxing to cruise at highway speeds and the car still seems to have good acceleration. I am happy with it and I think you will be, too.
     
  4. Yves

    Yves True Classic

    Hi Rodger it reassures me to have a comment from someone who also have this configuration. I admit that inside me I was worried about being disappointed.
    I imagine when climbing a slope of about 10-15 degrees we have to be downshift sometimes to a lower gear.

    Thanks for the encouraging comment

    Yves
     
    Last edited: Dec 11, 2018
  5. Yves

    Yves True Classic

    Hello guys there is my follow-up winter project for Kermit and the owner,
    The trany ugrade with the Strada ring and pignon is a success ....
    After about 100 Km I'm very happy with my decision, I drop easily ~1300 RPM when I'm cruising.
    That is a huge difference when you cruise on the highway.

    If you have the opportunity to have Strada ring and pinion don't hesitate. .... If you don't track with your X

    Happy guy! ... Thanks Rodger to support me
    Yves
     
    lookforjoe likes this.
  6. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    Nice job Yves. That is a big difference. I seem to recall others saying it would only make a small change in RPM, but good to hear that is not true. Do you feel much change in how it accelerates?
     
  7. lookforjoe

    lookforjoe True Classic

    That's a significant drop. 65-80 is a good highway cruising range around here, depending on traffic, and I find the X is way to buzzy with the stock final drive ratio when maintaining those speeds. If I wasn't swapping powertrains, I would go this route after the validations here.
     
  8. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    Also keep in mind the overall diameter (circumference) of the rear tires will affect the final drive ratio to some extent. I am hoping by running 15" wheels with a tall'ish sidewall profile it will help reduce the RPM's when cruising.
     
  9. fastx19

    fastx19 Administrator Moderator

    Location:
    Santa Clara, CA
    You will be very happy. 4k rpm will now equate to right around 80 mpg with 185/60 r13 tires. You will also see an increase in mpg as well. When I ran this setup, I did a road trip from Phoenix, AZ to Anacortes, WA. Averaged close to 40mpg.
     
    Dr.Jeff likes this.
  10. Yves

    Yves True Classic

    Maybe I interpret the tachometer reading too optimistically but it sure the RPM drop ~1200-1100.
    Regarding the acceleration I do not really feel the difference but probably there was a loss but it is really not significant versus the pleasure to cruise at highway speeds with lower noise.
     
    Dr.Jeff likes this.
  11. Yves

    Yves True Classic

    Yes the gaz mileage will be probably better, my tires size is 195/45R15.
     
  12. Brad Garska

    Brad Garska True Classic

    Location:
    Saline Michigan
    When I changed my ring/pinion to 17:64 I built a mathematical model >20 years ago to see the impact of changing various things such as final drive ratio, wheel/tire sizes. I ran the model with 195/45-15 with the stock 13:53 and with 17:64. I played with the RPM to get close to 80mph as a baseline. Results shown below.

    upload_2019-5-15_15-53-34.png upload_2019-5-15_15-53-11.png
     
  13. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    Brad, if I'm reading it correctly, the alternative final drive ratio (17:64) dropped the RPM at 80 MPH by 330 RPM?
     
  14. Brad Garska

    Brad Garska True Classic

    Location:
    Saline Michigan
    Yes that is correct. That said, the drop in RPM is very noticeable from the "feel" of the car. Although the discussion is focused mainly on the highway behavior, the "lengthening" of 1st and 2nd gear also contributes to a better "feel". I agree with the others that this is a worth while update.
     
  15. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    And that was with 15" wheels/tires as well. So I assume the drop in RPM would be a little less with just the final drive change (on stock size wheel/tires). I does not sound like much, but as you say it can feel noticeable. I had a vehicle with a automatic trans with a "overdrive" torque converter arrangement. The change in effective ratio was very slight with the overdrive, but you could really feel the difference when the OD feature was manually turned off.
     
  16. Ulix

    Ulix True Classic

    Location:
    Stuttgart, Germany
    Yves,
    3.58 / 4.08 = 0.877 is the factor that you multiply your old rpm with to get your new rpm after the swap.
    So if you ran 5000rpm before, you will run 4387rpm now.
    So 1200 - 1300 rpm drop sounds a bit optimistic to me.
     
  17. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    Could it be possible the gear ratio for your new final drive Yves is different from the ones being compared to? In other words, maybe a bigger drop in RPM due to different ratio than the ones used for calculations? Also Yves reported using 15" wheels/tires.
     
  18. Brad Garska

    Brad Garska True Classic

    Location:
    Saline Michigan
    I was thinking something didn't seem correct - I caught a typo on my input:rolleyes: I used 17:64 it should have been 17:61
    Here is an updated run. The RPM reduction in this case is ~515
    upload_2019-5-16_9-27-25.png
     
  19. kmead

    kmead Old enough to know better

    Location:
    Michigan
    Top image 3.64 final drive, .863 in 5th, 195/45 15

    33978822-CCEF-42BE-A197-A7F329B1F088.png

    OE 4.077 .863 and 195/45 15
    663BBF6B-A7E4-44ED-B67D-2B5ED5F4A453.png
     
  20. Dr.Jeff

    Dr.Jeff True Classic

    Location:
    Sin City
    That's a cool little program Karl.
     

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