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Lower the RPM

Discussion in 'Vans' started by euromopar, Oct 29, 2012.

  1. euromopar

    euromopar New Member

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    Hi there,

    I'm trying to lower the RPM on my Ram Van 1500. The car has a V6 3.9 and a 32RH tranny. I live in Europe (the Netherlands) and as u may know the speed limit on our roads is a bit higher than in the US.

    Now, owning this 1500 Ram Van I like to reduce the RPM's when I drive on the highways. I found out that it's not possible to swap the 32RH (3speed) for a 46RE (4speed) behind the V6. So maybe I can chance the gears in the rear axle? I think they came stock with 3:55 gears? Q, can I put 2:76 or something like that in the rear?

    Thanks for replays.


    Euromopar
     
  2. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Changing the axle gears will also reduce performance noticeably and may not give any better gas mileage, since you'll be pushing it harder to accelerate. There was a 3.21 axle ratio with this engine and transmission combination.
     
  3. euromopar

    euromopar New Member

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    Ok, So I could go for the 3.21 but that will not do much to the RPM at 60-80 mph.
     
  4. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Right. And it was offered with the 5-speed manual so as not to lose quite as much power. What are your specific goals?
     
  5. euromopar

    euromopar New Member

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    I’d like to save some gas while driving throughout Europe. Now with the 3 speed I go like 60 mph @ 2900 rpm. Better is like 2200 to 2400 RPM @ 60 mph.

    Euromopar.
     
  6. valiant67

    valiant67 ...

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    It isn't impossible to put the 4 speed auto OD transmission in the van, it's just rather expensive. Changing rear axle gears will be expensive as well.
     
  7. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Right. The 42RH with its 4-speed overdrive and a 3.55 axle will give you 1900-2000 RPM at 65 mph. But you need to change the driveshaft length and find a way to control the torque converter lockup and also the 4th gear engagement, which is electric.
     
  8. valiant67

    valiant67 ...

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    You also need the crossmember that is designed for the 4 speed auto. That part would have been used on the vans with the OD, such as the 5.2 V8.
     
  9. dana44

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    There are plenty of places to get the overdrive wiring stuff, given the 4spd auto got started as an overdrive for these big block Mopar engines and they had to figure it out. If a trans company (aftermarket) advertises the 4spd auto for big blocks, it has the simple setup to make it happen. You can also find ads in Mopar magazines.
     
  10. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Yes; however, the controllers cost several hundred dollars and a certain skill is required to do all this. It can be done, it just may not be worth it.
     
  11. dana44

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    http://www.dippy.org/forum2/index.php?topic=231.0
    Not difficult at all.

    • Years to Look For - Look for 1995 and earlier versions because they are easy to wire. The 2-pin A-518 unit needs one fuse protected hot wire and one switch controlled ground wire to control OD. The three pin A-500 and A-518 units need one fuse protected hot wire, one switch controlled ground wire to control OD and one switch controlled ground wire for LU. They can either be manually operated with toggle switches or set up to operate automatically with a control kit from Performance Automotive and Transmission Center or Jet Performance Products.
    • Years to Avoid - 1996 and newer A-500s and A-518s are entirely computer controlled, and should be avoided.
     
  12. euromopar

    euromopar New Member

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    @ Bob Lincoln, valiant67 and dana44, Thanks for the answers & advices. Finding a used 42RH or RE is no problem over here. The only thing for me to do is doing the calculation or as Bob says: It can be done, it just may not be worth it.

    Tanks for now, I’m going to read the articles as posted.

    Btw, the 1500 Van is an ex US army Van, used by de US army as a delivery Van in Germany. The car was built in Canada for export only.

    Greetings from Europe J

    Euromopar.

    For all you guys suffering from Hurricane Sandy, good luck and I’ll hope you get trough without major damage.
     
  13. bguy

    bguy Well-Known Member

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    2.97 was a common axle ratio for B250. You may already have it. IIRC my 87 used to be about that RPM. 3.21 was optional ratio.
     
  14. euromopar

    euromopar New Member

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    bguy, Do you think the B250 uses the same rear as the 1500 Van? I thought that mine came with a 3:55 stock?
    2:97 would be nice.

    Euromopar
     
  15. bguy

    bguy Well-Known Member

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    The 250 series would use 5 on 5" bolt pattern 15" wheels. If your van has this size the axle should drop right in in my estimation. An axle swap sure sounds easier and cheaper than a transmission or gear ratio change, even if you had to use different wheels on the back.
    Maybe some of the other forum members would know more of the minute details such as the difference with a 4 over 3 line brake system.
     
  16. valiant67

    valiant67 ...

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    I would expect there could be many variations in gear ratios. Gear ratios often varied by year, market (US spec and Euro spec may be quite different) and class (150/1500 vans can be subject to different standards than 250/2500 or 350/3500).
    Best to do would be to inspect the equipment label or look for a tag on the rear axle to determine what ratio your particular van has.

    The 5 on 5" bolt pattern means you can only look at 1985+ vans. Earlier ones would use a smaller bolt pattern.
     

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