![]() |
Register or Log In To remove these advertisements. |
|
|
![]() |
|
Thread Tools | Display Modes |
|
![]() |
#1 |
Registered User
Join Date: Oct 2013
Location: hindman ky
Posts: 40
|
'68 Chevy pulsation while driving.
I have a 1968 Chevy C10 250 six cylinder 3 speed on the column. It has been in my family from 1973 and the odometer has returned to 00000.0 four times so now it has 591000 miles on it(engine was rebuilt at 567000 but everything else is original.) It is mostly stock but I recently replaced the points with an HEI distributor. It has a pulsation that coincides with the speed of the wheels turning. It occurs in all gears and goes away when I press the clutch or go to neutral. There is no noise associated with it. I have replaced all four brakes also replaced front wheel bearings. I topped off the oil in the transmission and the rear end. I can usually figure out any problems with this truck but this one has got me. Thank you in advance.
|
![]() |
![]() |
![]() |
#2 |
Registered User
Join Date: Mar 2009
Location: WARRENSBURG,MISSOURI,64093
Posts: 1,518
|
![]()
Drive shaft throw a balance weight maybe? Or does the carrier bearing appear to be bad?
That's my guess....not sure. Ben ![]() |
![]() |
![]() |
![]() |
#3 |
Registered User
Join Date: Oct 2013
Location: hindman ky
Posts: 40
|
Re: '68 Chevy pulsation while driving.
Its a short bed so no carrier bearing, but the weight on the driveshaft is something I'll have to check. I suppose there should be some remains of whatever held the weight on. Thanks for the reply.
|
![]() |
![]() |
![]() |
#4 |
Senior Member
![]() Join Date: Dec 2013
Location: Gods country East,Tn
Posts: 8,545
|
Re: '68 Chevy pulsation while driving.
it's a drive line / clutch issue if it goes away when the clutch is pressed or placed in neutral . Have you checked the universal joints lately ? Also with that many miles it could be front yoke slop ...
![]() |
![]() |
![]() |
![]() |
#5 |
Registered User
Join Date: Nov 2015
Location: Brighton, Co
Posts: 13
|
Re: '68 Chevy pulsation while driving.
sounds like it ether threw the balance weight off the drive shaft or you could have u-joints going bad. Do you feel it in the seat or through the steering wheel?
|
![]() |
![]() |
![]() |
#6 |
Registered User
Join Date: Oct 2013
Location: hindman ky
Posts: 40
|
Re: '68 Chevy pulsation while driving.
I feel it in the seat. The u joints are fairly new I replaced the rear about three months ago and the front last spring. I didn't notice if it went back in in the same position(could have been turned 180 degrees.) Could that make a difference?
|
![]() |
![]() |
![]() |
#7 |
Registered User
Join Date: Nov 2015
Location: Brighton, Co
Posts: 13
|
Re: '68 Chevy pulsation while driving.
ok. And if you got the yoke miss aligned it will cause a vibration because the joints wont be "flexing" in sync. Did it start right after you did the joints or has this been an ongoing problem for a while? Worse case its possible something in the transmission could be coming apart.
|
![]() |
![]() |
![]() |
#8 |
Registered User
Join Date: Oct 2013
Location: hindman ky
Posts: 40
|
Re: '68 Chevy pulsation while driving.
It started out as barely noticable so I'm not absolutely sure when it started. t has been getting gradually worse over time. I suppose I could try taking the drifeshaft off and turning it 180 and trying it out. If it's a transmission problem wouldn't it make noise? Really hope it's not the tranny, I'm sure those transmissions aren't just laying around everywhere anymore!
|
![]() |
![]() |
![]() |
#9 |
Senior Member
![]() Join Date: Dec 2013
Location: Gods country East,Tn
Posts: 8,545
|
Re: '68 Chevy pulsation while driving.
You won't have too much of a problem finding a three speed cheap with so many guys going for 4-5 speeds and automatics . Just a few short years ago you couldn't give away a 250 6 with a 3 speed ,Now guys are buying them to put the trucks BACK to stock.
![]() |
![]() |
![]() |
![]() |
#10 |
Registered User
Join Date: Mar 2009
Location: WARRENSBURG,MISSOURI,64093
Posts: 1,518
|
![]()
You can try placing a worm screw hose clamp around the drive shaft and try driving a short distance, see what it does. Then re-clock the clamp at a different position, 6,9,12, 1 o'clock,etc. If it gets better, great, if worse, keep adjusting the clamp to see if its any better.
The weights they put on the shaft were spot welded, and as time goes by, they rust off..... Hth, Ben ![]() |
![]() |
![]() |
![]() |
#11 |
Registered User
![]() Join Date: May 2013
Location: WEST PALM FLORIDA
Posts: 1,174
|
Re: '68 Chevy pulsation while driving.
couple of guesses , clutch / presureplate , and pinion bearing .
__________________
68 Long Fleet , ly6 , turbo 350 , 3-5 drop , original paint , front discs 67 Small window , 7 foot bed , tweaked 6.0 LSX 2004R Medium Olive 58 Apache fleet , 235 , offy intake , dual exhaust , 4 on the floor , red/white 69 Long Fleet , Custom , 6.0, 4l60 , AC , Medium Olive |
![]() |
![]() |
![]() |
#12 | |
Registered User
Join Date: Oct 2013
Location: hindman ky
Posts: 40
|
Re: '68 Chevy pulsation while driving.
Quote:
![]() |
|
![]() |
![]() |
![]() |
#13 |
Registered User
Join Date: Apr 2013
Location: South Westerlo, New York
Posts: 1,325
|
Re: '68 Chevy pulsation while driving.
It would most likely be the rear end pinion bearing, parts in the rear end, tranny output shaft or ujoints if it coincides with truck speed.
__________________
Thanks, Joe.. 1969 C/10, 348 C.I., 3X2 bbl. V8, 2004r , LWB. |
![]() |
![]() |
![]() |
Bookmarks |
|
|