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Topped Out at 65 mph

Discussion in 'Early CJ5 and CJ6 Tech' started by eti engineer, Feb 6, 2016.

  1. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    As a pancake.

    H.
     
  2. Dave B

    Dave B Frankenjeep '67

    Not quite scientific enough and it may take more than 40? feet of track --
     
  3. mtdave

    mtdave New Member

    Getting into the debate late but REALLY??? you guys would drive one of these things that fast. On my maiden voyage to bring home my "57 CJ5 I hit nearly 45mph, never again. This daredevilette has never gone over 40mph again, I have no need for speed. In the next few weeks she's going to our new home in the country 20 miles on a two lane country highway with a 60-70mph speed limit, that's what they make trailers for.
     
    cookieman likes this.
  4. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Your Google-Foo is Indeed Mighty.:p

    The tire circumference may vary slightly depending on pressure & tire construction but it's pretty clear it doesn't change more than a few % and that distance traveled = circumference x revolutions

    H.:)
     
    eti engineer likes this.
  5. Dave B

    Dave B Frankenjeep '67

    Hope everyone recognizes the dangers of mixing the CJ with speed. Some apparently thrive on danger (they have a high threshold)--but even as a young man I drove a CJ2A cross-country 1200 miles and never topped 45 mph--guess mostly to spare the Jeep.
     
    Last edited: Feb 10, 2016
  6. Patrick

    Patrick Super Moderator Staff Member

    I drive my cj2a at 50-55 regularly. The CJ5 tops out at 65, and is quite comfortable there.
     
    eti engineer likes this.
  7. Glenn

    Glenn Kinda grumpy old man Staff Member

    It seems like nowadays there are so many rollover crashes that one might as well feel just as safe in a CJ.
     
  8. SFaulken

    SFaulken Active Member

    Meh, when I was back in Nevada, I'd regularly blast along at 70-75 in my CJ, being as there wasn't any other traffic to really be concerned with putting in danger. And that was before I had decent brakes and started working on fixing the steering geometry. Up here in the Seattle area, if I get it out on the highway, I generally run 60-65, and it's not terribly uncomfortable. It's all subjective.
     
  9. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    One reason it's subjective is because the sample is biased.

    Very few of the people who flipped a Jeep at 65 are still here to post about their experiences.
     
  10. SFaulken

    SFaulken Active Member

    Well, yes, there is that.
     
  11. Patrick

    Patrick Super Moderator Staff Member

    Maybe the 4" racing belts and full cage tied to the frame gives me false confidence?
     
  12. Glenn

    Glenn Kinda grumpy old man Staff Member

    It certainly gives you a better chance at survival. :)
     
  13. Mcruff

    Mcruff Earlycj5 Machinist

    The survival statement would apply to just about any old car made before about 1970. Seat belts used to be the first thing removed from cars when I was a kid. Have seen lots of people over the year ejected from the vehicle or turned into hood ornaments from lack of one. As for flipping virtually all old trucks suffered similar problems and a lot still do today.
    Driving sanely and with what your comfortable with goes along way to staying alive, along with upgrading your jeep to better aid your survival, one of the reasons I ditched the ross for saginaw, also why I added disk brakes and better seatbelts.
    I have driven mine a lot on the interstate at 70mph, wouldn't advise it on really windy days but other than that it runs fine that way.
    I have put about 20,000 miles on mine at mostly 55mph+.
     
  14. eti engineer

    eti engineer Member


    Nope. Like it says in my signature line, 4.27:1. This has been verified.
     
  15. Glenn

    Glenn Kinda grumpy old man Staff Member

    I know you said you used your GPS to be accurate, but did you happen to notice what the speedometer said? I'm really just curious about the difference in readings, in this case the speedometer would read slower.
     
  16. eti engineer

    eti engineer Member

    At 25 mph, the speedo was reading 5 mph slow. At 45, it was ten mph slow. At 65 mph on the GPS, it was reading around 12 mph slow.
     
  17. eti engineer

    eti engineer Member

    I have added power to my 9-inch brakes and have all new lines, hoses, shoes wheel cylinders and master cylinder on the vacuum booster. It stops nicely with little effort. I to have ditched the original steering for saginaw and tilt. I am not concerned with how fast the Jeep is on the highway, since it will be on a trailer behind my Xterra Pro-4X. You want a nice 4 X 4, the Xterra is top of the line as far as I am concerned. I was following my brother in his Bronco in Utah and using high-range when he was in low, with no problems. The Xterra has downhill descent control, selectable locking rear diff, traction control, a Rockford-Fosgate 380-watt sound system, heated seats, and a bunch of other nice things to have. But I still like the thrill of three sticks or more and muscling my way through rough terrain.
     
    Last edited: Feb 11, 2016
  18. termin8ed

    termin8ed I didn't do it Staff Member

    Thats about exactly what mine reads. I did regear with 4.27 from original 3.73 and have no idea what speedo gears are in tcase. Could be 5.38 gearing in that.
    I cant remember right now but im going to guess i had 31" tires on my old jeep with the 134. Right now with the v6 in my 69 i have 30" tires.

    I would have no problem driving mine 65 at all. With the work ive put into it the steering is tight and the springs are good. It handles nice. When i first got it with the old ross box and sloppy tie rods it was a little more scarry.
     
  19. Glenn

    Glenn Kinda grumpy old man Staff Member

    Cool, thanks for the info. I've never compared mine to anything accurate. :)
     
  20. PierreDnepr

    PierreDnepr Member

    Does it really matter? You'll find out that you F134 will top at different speed depending on the wind, hills, pavement quality, windshield up or down, canvas top on or off etc... the old engine, pass 55 mph, has very little oomph so anything out of the "perfect" condition will affect the top speed.

    I consider myself happy when I do 55mph and have a little pedal left. Sometime you get a good tail wind and hit 60 mph and you feel like superman! Most of the time it averages between 50 and 55 and the engine seems to be happy with that. Don't like it on a steep grade because it goes down to 40-45 mph pretty quickly. This is where I whish I had a 2 1/2 gear - eventually I'll add an overdrive for that reason alone.