perf-list-digest Friday, November 6 1998 Volume 01 : Number 139



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Ford Truck Enthusiasts - Performance
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In this issue:

FTE Perf - 300/6 vibration
FTE Perf - 300/6 vibration
RE: FTE Perf - 300/6 vibration
Re: FTE Perf - 300/6 vibration
Re: FTE Perf - 300/6 vibration

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Date: Thu, 5 Nov 1998 07:32:39 EST
From: WJeff43 aol.com
Subject: FTE Perf - 300/6 vibration

My '79 300/6 F100 has a vibration at 40 mph and again worse at 80 mph. Within
the last 6 months the following items have been replaced - rear end, rear
axles, rear wheel bearings, transmission, clutch and throwout bearing, both
universal joints, front king pins, steering arms and linkage, and front wheel
bearings. The truck still vibrates. It seems the only thing left is the
motor (in fact the vibration goes away if the clutch is pushed in). I have
seen mention of a rebuild service for a Ford harmonic balancer. Does the
300/6 have one. Does it have moving parts?
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Date: Thu, 5 Nov 1998 07:49:53 -0800
From: George
Subject: FTE Perf - 300/6 vibration

Except for it stopping when you push the clutch in, it sounds exactly like
an out of balance wheel(s). When you push the clutch in does your speed
drop below 40mph and possibly miss the vibration condition? Have you
balanced the wheels after the front-end work?

George Miller


My '79 300/6 F100 has a vibration at 40 mph and again worse at 80 mph.
Within
the last 6 months the following items have been replaced - rear end, rear
axles, rear wheel bearings, transmission, clutch and throwout bearing, both
universal joints, front king pins, steering arms and linkage, and front
wheel
bearings. The truck still vibrates. It seems the only thing left is the
motor (in fact the vibration goes away if the clutch is pushed in). I have
seen mention of a rebuild service for a Ford harmonic balancer. Does the
300/6 have one. Does it have moving parts?


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Date: Thu, 5 Nov 1998 12:13:40 -0500
From: Sleddog
Subject: RE: FTE Perf - 300/6 vibration

i haven't had this problem, but some points to consider. i have 2 bent
rear axles in my 77 and at any speed there was no vibration. i found the
bent axles one day after breaking in new rear gears on jackstands. it was
noticeable to the eye and i felt the truck moving a little. but on the
road (and in excess of 100 mph many times) there was never any vibration.

i had u-joints go out causing vibration, but you replaced those already.

the balancer has no moving parts really, and i doubt that that is it, as
the vibration would be engine speed, not vehicle speed dependant. yes, all
engines have one too. (except some unusual examples of rare engines,
prototypes, old designs, extremely large industrial/marine engines, etc.)

do you have bias ply tires? if yes, get rid of them! sitting for a short
time they get flat spots and will go outta balance.

it sounds like a tire imbalance. do you feel it in the steering wheel as
well?

it may be a clutch misalignment or something in there unbalanced or not
assembled right, but i don't know for sure. i would check the tires'
balnce first, and wear patterns and rims for any oblonged/worn lug holes,
bent, etc.

do not get them bubble balanced, spin balancing is the only way for
balancing unless you always drive VERY slow.

sleddog

- ----------
From: WJeff43 aol.com[SMTP:WJeff43 aol.com]
Sent: Thursday, November 05, 1998 7:32 AM
To: perf-list ford-trucks.com
Subject: FTE Perf - 300/6 vibration

My '79 300/6 F100 has a vibration at 40 mph and again worse at 80 mph.
Within
the last 6 months the following items have been replaced - rear end, rear
axles, rear wheel bearings, transmission, clutch and throwout bearing, both
universal joints, front king pins, steering arms and linkage, and front
wheel
bearings. The truck still vibrates. It seems the only thing left is the
motor (in fact the vibration goes away if the clutch is pushed in). I have
seen mention of a rebuild service for a Ford harmonic balancer. Does the
300/6 have one. Does it have moving parts?





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Date: Thu, 05 Nov 1998 18:58:42 -0500
From: Tim Turner
Subject: Re: FTE Perf - 300/6 vibration

WJeff43 aol.com wrote:
>
> My '79 300/6 F100 has a vibration at 40 mph and again worse at 80 mph. Within
> the last 6 months the following items have been replaced - rear end, rear
> axles, rear wheel bearings, transmission, clutch and throwout bearing, both
> universal joints, front king pins, steering arms and linkage, and front wheel
> bearings. The truck still vibrates.

Among the other good suggestions already posted you might want to check
for a driveshaft problem; bent or imbalanced.. (slung a balance weight
off of it perhaps)?

Tim Turner/Manic Mechanic
Wilmington NC
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Date: Thu, 05 Nov 1998 22:22:53 -0600
From: Mike Schwall
Subject: Re: FTE Perf - 300/6 vibration

At 06:32 AM 11/5/98 , you wrote:
>My '79 300/6 F100 has a vibration at 40 mph and again worse at 80 mph.
Within
>the last 6 months the following items have been replaced - rear end, rear
>axles, rear wheel bearings, transmission, clutch and throwout bearing, both
>universal joints, front king pins, steering arms and linkage, and front wheel
>bearings. The truck still vibrates. It seems the only thing left is the
>motor (in fact the vibration goes away if the clutch is pushed in). I have
>seen mention of a rebuild service for a Ford harmonic balancer. Does the
>300/6 have one. Does it have moving parts?

After changing the 3rd member on my '78 F150, the truck developed a bad
driveline vibration between 55-65 MPH. The vibration is in the driveline
because when I push the clutch in, it stops. I tried everything from
turning the u-joints 180 degrees to jacking up the rear end and and free
spinning the wheels. It turned out to be a bad output shaft bushing in the
transmission. Weird thing is, the bushing was obviously bad before I
changed the 3rd member. i guess the pinion angle change some other change
made the bad bushing cause a vibration. The vibration is so bad that I
can't hold the shifter for very long or my hand starts to itch from the
vibration.

My advise would be to make sure the u-joints are good - they move freely
with no rough spots in the range of movement. try rotating the ujoints 180
degrees. if you want to spend the money, have the driveshaft checked for
balance. And check the output shaft bushing of your tranny (move the
driveshaft yoke up and down at the tail of the transmission). If it moves
a lot, it may be the bushing.

Mike

_____________________________________________

Email: mschwall texas.net or mike fordfan.org
Home Page: http://www.ford-trucks.com//lc/lc.php?action=do&link=http://mschwall.home.texas.net
FORD FAN SITE: http://www.ford-trucks.com//lc/lc.php?action=do&link=http://www.fordfan.org

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End of perf-list-digest V1 #139
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