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Car jerking at 100km speed

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    #1

    Car jerking at 100km speed

    My 88 CP has recently started giving a significant jerk when it reaches the 90 - 100 kmph range. Earlier it could be felt very slightly when the car shifted into overdrive but now it is actually alarming. All other gear shifts are normal, and once I'm upto speed of 120kmph on the highway it goes smoothly. The transmission oil level, colour, odour and consistency are all normal. Acceleration and shifts are all smooth till the speed of 100 kmph is reached.
    Please advice, Thanks.
    sigpic1988 Colony Park
    Tags: None
    #2
    So let me see if I have this straight; There is a single jerk at kph (60 MPH)? no more after that? When you decelerate back down to 0 there is nothing unusual and besides the jerk it shifts fine without any unusual sounds or actions?

    I have no idea. (I'm just getting this back to the top for you) But wouldn't a bad torque converter lock-up clutch maybe do this? Cougo
    2001 GM LS 25K miles (now 31K) ABS, Auto Climate, Power Dual Leather (dark charcoal),
    Drifting Barge Pkg.

    Comment

      #3
      How old are your cap, rotor, and plug wires?

      85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
      160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
      waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

      06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

      Comment

        #4
        How many kilometers/miles on that baby? I think its transmission related. When the atf was changed?
        “Cars are the only thing on earth that will beat you, break you, make you bleed, make you cry, spend all your money, spend all your time, not work and not care that you will love more, the more they abuse you.” -Anonymous

        Comment

          #5
          take it out of overdrive under 100 kmph

          1986 lincoln towncar signature series. 5.0 HO with thumper performance ported e7 heads, 1.7 roller rockers, warm air intake, 65mm throttle body, 1/2" intake spacer, ported intakes, 3.73 rear with trac lock, 98-02 front brake conversion, 92-97 rear disc conversion, 1" rear swaybar, 1 3/16" front swaybar, 16" wheels and tires, loud ass stereo system, badass cb, best time to date 15.94 at 87 mph. lots of mods in the works 221.8 rwhp 278 rwt
          2006 Lincoln Town Car Signature. Stock for now
          1989 Ford F-250 4x4 much much more to come, sefi converted so far.
          1986 Toyota pickup with LSC wheels and 225/60/16 tires.
          2008 Hyundai Elantra future Revcon toad
          1987 TriBurner and 1986 Alaska stokers keeping me warm. (and some pesky oil heat)

          please be patient, rebuilding an empire!

          Comment

            #6
            When do you shift into od at no throttle?

            Early shifting into od could aggravate ignition misses, and also indicate an improperly adjusted tv cable, which could lead to trans slippage.

            85 4 door 351 Civi Crown Victoria - Summer daily driver, sleeper in the making, and wildly inappropriate autocross machine
            160KMs 600cfm holley, shorty headers, 2.5" catted exhaust, 255/295 tires, cop shocks, cop swaybars, underdrive pulley, 2.73L gears.
            waiting for install: 3.27's, Poly bushings, boxed rear arms, 2500 stall converter, ported e7's, etc

            06 Mazda 3 hatch 2.3L 5AT (winter beater that cost more than my summer car)

            Comment

              #7
              Originally posted by johnunit View Post
              How old are your cap, rotor, and plug wires?
              +11111
              sigpic


              - 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims

              - 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust

              - 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock

              Comment

                #8
                Originally posted by Cougo View Post
                So let me see if I have this straight; There is a single jerk at kph (60 MPH)? no more after that? When you decelerate back down to 0 there is nothing unusual and besides the jerk it shifts fine without any unusual sounds or actions?

                I have no idea. (I'm just getting this back to the top for you) But wouldn't a bad torque converter lock-up clutch maybe do this? Cougo
                Yes it jerks at 60mph only. Sometimes two or even 3 quick jerks. While decelerating down either quickly by braking or by taking my foot of the gas pedal there is no jerking or any unusual clunks or stuff. All other gears shift fine.
                sigpic1988 Colony Park

                Comment

                  #9
                  Originally posted by 1990LTD View Post
                  +11111
                  Cap, rotor and plug wires are about 4 years old. Plugs are a year old, and the old ones looked normal at the time they were replaced.
                  sigpic1988 Colony Park

                  Comment

                    #10
                    I automatically suspect ignition parts on these cars that are older than 6-10 months if it's running funny
                    sigpic


                    - 1990 Ford LTD Crown Victoria P72 - the street boat - 5.0 liter EFI - Ported HO intake/TB, 90 TC shroud/overflow, Aero airbox/zip tube, Cobra camshaft, 19lb injectors, dual exhaust w/ Magnaflows, Cat/Smog & AC delete, 3G alternator, MOOG chassis parts & KYB cop shocks, 215/70r/15s on 95-97 Merc rims

                    - 2007 Ford Escape XLT - soccer mom lifted station wagon - 3.0 Duratec, auto, rear converter delete w/ Magnaflow dual exhaust

                    - 2008 Mercury Grand Marquis Ultimate Edition - Daily driver - 4.6 2 valve Mod motor, 4R75E, 2.73s. Bone stock

                    Comment

                      #11
                      Originally posted by 90ltd View Post
                      How many kilometers/miles on that baby? I think its transmission related. When the atf was changed?
                      200,000km, and the ATF and transmission filter were changed a year ago because I was getting a jerk when shifting from 1 to 2. That problem went away after that.
                      sigpic1988 Colony Park

                      Comment

                        #12
                        Are you running any transmission cooler on it? If not, change fluid, if it shifts fine again put the biggest transmission cooler you can fit behind the grille on it.

                        Alex.

                        Comment

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