Wheel Hop |
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JMS48
New Member Joined: 17-November-2019 Location: Glenside Status: Offline Points: 5 |
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Posted: 01-December-2019 at 2:23PM |
Hi,
I have a 72 GTS with a 4 speed. I’m looking to see if there’s anyone else that has issues with wheel hop. If so what can be done to correct the problem.
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californiajohnny
Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14609 |
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give us a few more details... like air shocks, is the rear raised or lowered, condition of the bushings, shocks, springs, trac lock diff, sticky tires???
mine is raised and has a trac lock it doesn't hop at all but the GM cars of this era have a similar 4 link suspension and when raised tend to hop! the cure for them is to extend the upper arm mounts about 1 1/2" so that the upper arms are level to angled down at the front mount as the rearend torques rearward at the top pulling the rearend up off the ground so by raising the upper mount on the rearend it is now trying to lift the body forcing the rearend down on the ground but this usually isn't the issue with these cars... |
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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Steve M.
Senior Member Joined: 08-June-2019 Location: Florida Status: Offline Points: 1755 |
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I had a similar issue on my '76. My car came with stock suspension and air shocks. I replaced my rear springs, added a rear sway bar, and got all new bushings. The springs are MOOG CC 803 station wagon springs. The shocks are KYB Xel-G No wheel hop at all. The roads in Florida are flat. Once I get on a long distance road trip in, I'll know if my set up cured all of my wheel hop.
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Steve M.
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JMS48
New Member Joined: 17-November-2019 Location: Glenside Status: Offline Points: 5 |
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Hi,
As far as I can tell it’s the stock suspension, no air shocks. No sticky tires ... yet .... stock 14 in rims. Guess I’ll run thru the suspension and look into replacement of bushings and coils. |
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72 RancheroGT
New Member Joined: 08-November-2019 Location: Kansas Status: Offline Points: 18 |
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Another cause of wheel hop is unequal u-joint working angles. As a shaft with u-joints rotates the shaft doesn’t turn at a constant velocity, it speeds up and slows down twice per revolution as the joint “breaks over”. If the working angle of the joints is equal +- 1 degree the speed variation is cancelled out. If the angles are not equal the drive shaft will drive the pinion at with the same speed up/slow down twice per revolution. That causes the tires to do the same thing which causes wheel hop, it will also cause a high frequency vibration during normal driving. This vibration will be about 5 or 6 times faster than a wheel vibration and it won’t be as strong, but it will be noticeable. Sometimes the vibration can also be heard, it will sound like a constant tone you might get oil of a subwoofer.
On leaf spring suspensions the pinion nose “ roles up” under heavy acceleration because the leaf springs allow it to. When it rolls up the working angle of the pinion u-joint “flattens out” while the angle at the trans changes very little causing the pinion to drive at a non-constant velocity and the wheels to do the same. The leaf springs then would wind up and unwind in response making the pinion angle change even more, and it kinda turned into a vicious circle that could get pretty violent. The old slapper bars, or traction bars prevented the leaf spring wind-up and the resulting pinion angle changes. They actually worked pretty well. So, back to your car, if your working angles are right at the edge of being too different from each other and you accelerate heavily, that causes the pinion to roll up due to the rubber suspension bushings. Then you get the non constant velocity of your pinion, and wheel hop. Another cause could be old worn sloppy rubber bushings allowing the rear axle to wind up. To check the angles you need to measure the angles of the output shaft and the pinion, they should be the same, that is the output shaft and the pinion should be parallel. Raising the rear end can cause them not to be parallel. The output shaft angle cad be measured but measuring the angle of the starter housing or the engine oil pan. You can’t use the trans pan because it is angled compared to the transmission shaft, but the started and the oil pan engine oil pan rail are both in the same angle as the crankshaft and transmission center lines. The pinion can be measured by putting the back edge of the protractor on the pinion bearing support bolt heads. All of this velocity change stuff is why front drive cars have “constant velocity” joints. As the front wheels are steered the angles of u-joints cause velocity changes and vibrations, so they have to run CV joints. Anyway, hope this helps with your wheel hop.
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californiajohnny
Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14609 |
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yes this is true^^^
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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Rockatansky
Senior Member Joined: 30-July-2010 Location: On The Road Status: Offline Points: 6072 |
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they're saying here it's bushing deflection my 72 Q code used to wheel hop so violently the radio knobs fell off and the side window came out of the track. the radio knobs were not loose but the window track may've been a POS i've always heard it's the result of the loading and unloading of the suspension aggravated by axle wrap whatever that means
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72 GT Ute
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unlovedford
Senior Member Joined: 17-December-2010 Location: Tennessee Status: Offline Points: 10142 |
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I had a '72 GTS Sportroof with the 4 speed and factory competition suspension package. All factory and the rear end would hop like mad. Replacing the control arm bushings did not change anything as far as the hop. I sold the car before I dug deeper, but you are not alone.
My concern is that I'll have the same issues with my wagon when I get the 5 speed and 5.0 in it. It'll have far more oomph than the CJ engine had, so I'm replacing the bushings, adding a sway bar, stiffer springs, better shocks and boxing the lower arms when I finish the swap. |
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Joe
1972 Mom's Squire Wagon 1972 Torino Wagon 1976 Torino 1968 Cougar XR7-First batch 1972 Torino 460 1989 BroncoII/Jeeps/Titanimous Popeye and Brutus (Rams) |
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unlovedford
Senior Member Joined: 17-December-2010 Location: Tennessee Status: Offline Points: 10142 |
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Actually, the term "wheel hop" does not accurately describe what mine felt like. More of a "The Earth was pounding upward on my car with a 5,000# sledge rapidly, while gravity was bitch-slapping it back down again with the force of a semi truck" sort of experience.
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Joe
1972 Mom's Squire Wagon 1972 Torino Wagon 1976 Torino 1968 Cougar XR7-First batch 1972 Torino 460 1989 BroncoII/Jeeps/Titanimous Popeye and Brutus (Rams) |
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72 RancheroGT
New Member Joined: 08-November-2019 Location: Kansas Status: Offline Points: 18 |
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Yeah, it can get really violent right up until something breaks.
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Craig
72 Ranchero GT (Clone) “Confidence is the feeling you have right before you fully understand the situation” |
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californiajohnny
Moderator Group Joined: 05-October-2013 Location: winlock, wa Status: Offline Points: 14609 |
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boxing the lower arms and poly bushings will be a much added improvement
i have to laugh at the camero guys, back in the day... threw on a set of slapper bars not shimmed up like they should be (damn near digging in the pavement) then wonder why it still hops ( the snubber needs to be 1/4" to lightly touching to keep the spring from winding up) |
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JOHN
74 GRAN TORINO S&H CLONE 74 VETTE CUSTOM 90 S10 BLAZER 4X4 LIFTED 77 CELICA CUSTOM 75 V8 MONZA SUPERCHARGED 79 COURIER VERT. SLAMMED 75 VEGA V6 5 SPD 70 CHEV C10 P/U 68 MUSTANG FB CONVERSION |
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72FordGTS
Admin Group GTS.org Admin Joined: 06-September-2005 Location: Ontario, Canada Status: Offline Points: 5846 |
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I have poly bushings on my car and zero wheel hop. Manual cars seem to suffer from it worse, but I'd suggest starting with poly bushings and going from there. Rubber just deflects too much.
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Vince
1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
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Billy C
Senior Member Joined: 10-February-2010 Location: Pittsburgh, PA Status: Offline Points: 948 |
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I get wheel hop with the 275 R888 when I break it loose really hard in a straight line. In turns it will just loose grip and throw the back end out pretty smoothly. The 255 all season street tires will break free without any wheel hop. All mounting points will impact wheel hop as well as geometry and tires. Motor mounts can even aggravate wheel hop if they move too much.
Stock suspension pickup points Rod end lower arms Stock uppers with poly Ford Trac Loc with fresh clutches (maybe not anymore) definitely not perfectly aligned drive shaft joint angles TKO600 sprung clutch stock motor mounts and trans mount |
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-Billy Conturo
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