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Vibrations

 
lit549 lit549
V-6 Camaros rule! | Posts: 35 | Joined: 06/13
Posted: 06/18/13
06:03 PM

I have a 85 chevy c10 that has fairly new Motor,trans(350c),newly balanced drive shaft/u joints.New Cooper tires,and factory 10 bolt rear end.Truck has been lowered right with 4-6 kit.I have a vibration at 45-55 mph ,I've done the coast in neutral test and it quitscompletely.This vibration was there with old wheels/tires and original engine/trans.Front suspension is all new also.Pinion and trans angles are correct..Any suggestions? Either it's a bad shaft or rear end.The vibration is slight but annoying,Its completely smooth at 70 mph.Can warped motorist drums do this?Thanks in advance!  

waynep712222 waynep712222
V-6 Camaros rule! | Posts: 122 | Joined: 03/13
Posted: 06/18/13
08:52 PM

get the truck up in the air... where you can get under it safely.... with the parking brake on firmly.. and the transmission in neutral.. so the drives shaft is NOT locked in a bind holding the truck in place..

now... push upward on the front driveshaft yoke where it slips into the tail housing of the transmission....

you are going to find slight movement and thats all it takes...

curious... did you change out the 700R4 that came in that truck for the TH350C


timken #5200 is the output shaft seal and tail shaft bushing kit.. you may find you want to replace the big oring on the rear housing...  and the speedo oring and any speedo driven gear housing seal if used...

please... test fit the installed bushing before installing the seal in the rear housing...  slip the housing over the yoke.. you may need to use a tool to remove the mushroomed ridge of the bushing from where you drove it in...  just the edge usually...  you don't want it TOO TIGHT... its a slip fit and lubed with ATF from the transmission..

you can depending on where you live... get the rear seal and the rear bushing from transmission parts suppliers...but they are rarely listed widely in the yellow pages.. these places sell soft and hard parts to transmission rebuilders...


this is just one of the possible sources of vibration.. but the most likely from your description...

you could also have a driveshaft that was not properly balanced.. or got bent after installation... what..

some tire shops use a short tilt up  hydraulic lift that you drive over and it lifts on the frame.. these are drive shaft benders on some models...

i had a customer who drive shaft got bent on one of these...  i got another drive shaft built..  he took the bill to the tire shop and presented it.. they said.. let us show you .. it that lift does not bend drive shafts... so he let them put the car up. and bent the custom driveshaft..  he then returns to me complaining the drive shaft is bent again... when i look and find the same mark.. i almost had to beat it out of him what happened...   this is like getting shocked by grabbing the coil wire..  then after you get out of the hospital.. showing people how you ended up in the hospital by grabbing it again..  

lit549 lit549
V-6 Camaros rule! | Posts: 35 | Joined: 06/13
Posted: 06/18/13
10:17 PM

Well,I had the trans rebuilt from a reputable shop.The same vibration was there before rebuild or balancing the drive shaft.I thought all that would fix it but it didn't.The trans is what came in that truck,350 with lockup converter.The only things I haven't redone is brakes,or rear diff..Rear axle bearings have a little closeness to them but not much(can hear it when moving wheel while jacked up)   .I'll chevy the yikes while unloaded,haven't thought of that.  

waynep712222 waynep712222
V-6 Camaros rule! | Posts: 122 | Joined: 03/13
Posted: 06/19/13
12:09 AM

one last thing...

i know you said its a 350.. can you check the block number?? either on the back of the block above where the transmission mounts.. you will need a mirror and a bright flashlight..

also take a look at the harmonic damper..  is it smooth all the way around the outside.. or is the outside diameter stepped???

smooth..----------------------- usually found on 350 engines

stepped -------____________------ usually found on 400 engines.

this mis installation will usually make the rear view mirror almost shake its self off the windshield..

flex plates are also weighted differently.

if your axle bearings in the rear are bad... i cannot say that at some speeds.. they won' t cause a harmonic as the axle bounces around..

time to pull the drums and lift the axles in the housings..  C10s are usually equipped with C clip axles.. with the bearing rollers riding directly on the axle shaft ... they can wear DEEP grooves in the axle shaft..  surface imperfections can be fixed with installing repair bearings that move the rollers out past the worn area... loaner tools are available at some stores to save HOURS of time extracting these press in the housing bearings..  

lit549 lit549
V-6 Camaros rule! | Posts: 35 | Joined: 06/13
Posted: 06/19/13
03:25 PM

Ok,I check truck while jacked up and the right rear tire(fairly new Cooper) has a slight bulge on the side wall and it looks like it wobbles while rolling-broken chord internally??? And next I put truck in neutral and pulled up/down on shaft at the trans and it does have slack..It's the yoke not the :-)joint,should this have any movement up and down?? I'm thinking no..Maybe I've found the problems??Keep in mind,these tires don't have but maybe 1-2 thousand miles.  

redneckjoe69 redneckjoe69
Everything in my driveway’s a Chevy | Posts: 612 | Joined: 02/10
Posted: 06/20/13
05:56 AM

i was talking with a guy who had a similar problem.    he found his tranny mount was broken, so he bought a new one at the parts store.   installed it, went for a ride, and found out he had an odd vibration.  
   after racking his brain for days, he decided to get another tranny mount, since it was the only thing he changed.   it solved his problem.
   the only difference in parts noticed was, the first one was made in china.   same store, same part number, same LOOKING rubber mount.  

   might be worth having your tires re-balanced too?    especially if you have a bubble already with those low miles.   might be under warranty?

   hope you get it figured out!
                        Joe  

lit549 lit549
V-6 Camaros rule! | Posts: 35 | Joined: 06/13
Posted: 06/20/13
07:59 AM

Hey thanks Joe! I'm working on getting the tire replaced and truck back to the guy who done the trans.I was just wanting to know if some play was normal at tail shaft so I can go in armed with facts when they try to say,"that's normal".. To me,it shouldn't move at all there! I've been chasing this vibration in driveline for awhile and honestly,I'm just about done messing with it !
Aggregating as he'll!  

redneckjoe69 redneckjoe69
Everything in my driveway’s a Chevy | Posts: 612 | Joined: 02/10
Posted: 06/20/13
11:18 AM

a rubber mount will give you a tiny bit of movement.   poly mounts are notorious for giving vibrations and other issues sometimes.
  i'd check the tires first.    kinda seems like a likely suspect with the bubble?  a possible safety issue too?    alot of tires are made over-seas today, and have recalls now & then.    maybe its under warranty with your low milage?  

pepsi1 pepsi1
Big Block power for the win | Posts: 940 | Joined: 03/11
Posted: 06/20/13
02:07 PM

This is a true story: I purchased my wife a 1981 Z28 new the last of the style for here birthday in 1981 it was loaded and NEW. We were on the highway just cruising. Then the speed limit was 55. Thats just where the vibraction was. Long story short. The Vibration got worse. The dealer said they couldn't find anything wrong. The service manager was also a fireman. He said you Bob The speed limit is 55MPH. He just side stepped anything and everything. He then said I was only kidding. But he was correct the speed limit was 55MPH.They did what GM would let them do...LOL...I was never so Pizzed.
   One night going to a fire her car was first. I put it in gear and (loud bang) came from the torque convertor area. The car didn't move of course. When I got back from the fire hours later I had to dig into it. It had to be something really @#$% up. I found the convertor bolts had fallen out. Confused   Mad In fact there was a plastic inspection cover. The bolt actually punched holes in the cover.
  There was only(2)  convertor bolts that was originaly in the torque convertor. "That was the original vibration" They fell out.The mounting holes actually were oval shaped the flex plate. I put 3 nut and bolts in it and went to the dealer the next morning. I made them replace the flex plate the plastic cover the bolts went threw it. I never had a problem with it after that. It was stolen...The last of that generation. "I bitched about it enough that GM extended the warranty to 50,000".

  I WANT TO SAY THIS ABOUT DRIVELINE VIBRACTION. For example only: If the Vibration was at 30mph, the next vibration should come back at  you should get that vibration back at 60 mph, then 120, 240 etc. Vibrations have a tendency of squaring themselves..Just some FYI. It's also murder on engine bearings, and other internal engine parts.  Grin  Cool  

Bob  

lit549 lit549
V-6 Camaros rule! | Posts: 35 | Joined: 06/13
Posted: 06/20/13
02:19 PM

I have already went through all of that,checked all accessories on front of engine,balancer,converter,New flex plate..This vibration has been there since it was factory(when I got it),two sets of wheels,tires,and trans before and after rebuild.Like I say,@ 70 -85 (fastest I've been in it) it's smooth..Just 45-55 mph it vibrates,not real bad but very noticeable..  

lit549 lit549
V-6 Camaros rule! | Posts: 35 | Joined: 06/13
Posted: 06/20/13
02:19 PM

I have already went through all of that,checked all accessories on front of engine,balancer,converter,New flex plate..This vibration has been there since it was factory(when I got it),two sets of wheels,tires,and trans before and after rebuild.Like I say,@ 70 -85 (fastest I've been in it) it's smooth..Just 45-55 mph it vibrates,not real bad but very noticeable..  

waynep712222 waynep712222
V-6 Camaros rule! | Posts: 122 | Joined: 03/13
Posted: 06/20/13
09:36 PM

break out the cell phones and the bluetooth ear pieces..

follow the car down the highway...  when it starts to shake.. the driver should hold it steady at the shake speed while you drive around it or as a passenger you have the driver of the second car move around the car while you observe the  tires ...

see if you note any shaking from the tires...

you might have an old camcorder that does 1,000 or 2,000 frame per minute..    you might catch something with that..

there are also electronic chassis ears...  some models are cheep.. some are serious investments... some dealers have them .. some drivability techs have them..

Steelman Chassis Ear STE 97215
Prodmainimg142

i have not used these and i think there is a more advanced model.. that gives you frequencies of the vibrations..  

waynep712222 waynep712222
V-6 Camaros rule! | Posts: 122 | Joined: 03/13
Posted: 06/20/13
09:47 PM

i have a stupid idea...

take a clear plastic cup with a lid..     place it with some colored water.. part way full... on the engine.. and raise the engine speed.. with the transmission in park or neutral...  is the liquid  smooth or does it start to bounce???

try it on several other motors.. see how the liquid responds..

with 350s.. was your engine rebuilt???   did they reinstall your crank...  was it a 350 crank or a 305 crank.. the casting numbers are the same... but the balance is slightly different because the 305 uses lighter pistons..

are all the spark plug wires separated???

can you examine the pickup coil for signs of cracks in the second layer.. causing random spark generation .  its happened before...

who adjusted the lifters???  are they anti pump up lifters that make noise at idle.???  get those too tight. and you might be holding a valve open at higher engine speeds when the lifters pump up with the increased oil pressure..

when the engine was built.. did you get a balance card from the balance shop???  or with the build info..

years ago.. decades ago.. my family ordered a balanced engine for one of our cars.. they actually charged us for the fully counterweighted crank..  like 150 extra in the mid 70s...  when a valve turned loose 18 years later.. and i pulled the engine down.. it was just a standard crank with properly balanced rods..  

lit549 lit549
V-6 Camaros rule! | Posts: 35 | Joined: 06/13
Posted: 06/20/13
10:28 PM

Yup,I've been home hurt since Dec and I've been working on this thing a lot.I've been through all of that,found the accel hei advance was sticking so I installed New msd prob solved.Checked every wire with volt mtr,all good.Put New plugs,by reading plugs found I'd been running lean;rejetted,prob solved.Ran valves 3 times,tried adjusting while running,last 2 times I did them right(one at a time) to 0 lash then 1 turn.No vac leaks,but still idles a little rough.It's a 96 vortech 350,zz 4 cam with comp springs and lifters.Springs are Beehive ls springs so no matching required  for more lift.vortech heads with port matched intake.600 edelbrock,rpm intake(Chinese one),stock compression standard bore.Timing is at 32 deg,vac advance set to 12 deg advance(ported),and it doesn't vibrate in park just going down the road..Getting new tire tomorrow then back to trans shop to look at out put shaft slack.Should know more by this time next week.Oh,the motor was  all factory internals and we didn't balance it.Those frequency meters are cool,I may look into that! Sweet  

lit549 lit549
V-6 Camaros rule! | Posts: 35 | Joined: 06/13
Posted: 06/20/13
10:30 PM

Oh,the engine has about 6k on it and trans has maybe 1000.And one other thing I noticed when I pull shaft out the other day,and no trans fluid came running out? Weird.  

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