Need Diagnosis Shop in Colo Springs....More Truck Vibration!

[jeff in co]

Tried the front wheel drive thing this morning. Pulled rear driveshaft off and then away I went in FWD only.

Result, same vibration there. So, good news I guess is that the rear driveshaft and pinion angles are probably all good. Bad news, it's got to be within the engine/tranny somewhere.

Flywheel, torque converter, harmonic balancer??? I'll keep thinking of anything else to try but it's getting harder.

I did look at the balancer, and it does look to be in pretty decent shape. I don't see any cracks or deterioration in the rubber ring thing. So don't know.....

I'll just keep driving it for now unless I get some new ideas.

 

[miniwally]

Without reading the entire thread again, have you driven it now without the front driveshaft in.

I know with hubs it shouldn't spin, but maybe you have a hub hanging up and your spinning the front shaft all the time? If it isn't the rear, and you verify it's not the front, then you have an internal issue, something wrong with gears, axle shafts, or an internal issue with something.

 

[ChrisPerry]

okay, flipping through you have

1-changed motor and trans mounts.....................still there
2-swapped t-case....................................................still there
3-ran without:
a....rear tires and brake drums on jack stands.....still there
b....rear d-shaft.....................................................still there
c....front d-shaft....................................................still there
4-ran with t-case in neutral..................................still there

Seems to me that the vibration is in the engine, trans, or t-case input shaft.

Only thing left to try that I can think of, is to run it up to speed and shift into neutral. See if it vibrates at 70 with the engine idling. If it still vibrates it's trans or t-case input. If it doesn't then it's engine, torque converter, or trans input shaft.

 

[jeff in co]

okay, flipping through you have

1-changed motor and trans mounts.....................still there
2-swapped t-case....................................................still there
3-ran without:
a....rear tires and brake drums on jack stands.....still there
b....rear d-shaft.....................................................still there
c....front d-shaft....................................................still there
4-ran with t-case in neutral..................................still there

Seems to me that the vibration is in the engine, trans, or t-case input shaft.

Only thing left to try that I can think of, is to run it up to speed and shift into neutral. See if it vibrates at 70 with the engine idling. If it still vibrates it's trans or t-case input. If it doesn't then it's engine, torque converter, or trans input shaft.

Yep, pretty much nailed everything! Well done!

I'll give your idea a shot....thanks.

 

[kgblazerfive]

What is the engine ?

I had a 400 that somebody put a 350 flex plate on had a small but distinct vibration took for ever to figure it out. Finally did, changed the flex plate sold the Blazer. Crankshaft broke in half not to long after that. Guess it did not like being balanced after not being balanced for so long.

 

[Zeus33rd]

Make sure everything is clean. No dirt, grease, mud, rust, fluids or anything that would make it hard to see cracks.

Look at motor mounts and t-case mounts, the actual part you buy, and all of the surrounding areas and both ends of any cross-members. And I mean get your actual eyeballs as close as you can. Look for cracks, loose rivits etc. Even if you replaced it all a week ago, do it again, and be more thorough.

Grab the flex plate by hand if you can, or use a prybar/screwdriver etc and try to move it around. Separate the flex plate from the torque converter and see if everything feels/looks right. Put the tcase in low range...see if the pitch of the vibration changes. Check out all the pulleys and harmonic balancer/crank bolt. Put a wrench on the flex plate bolts and every bolt on everything that is attached to all of the parts you've narrowed it down to. All bell housing bolts, starter bolts, trans/tcase adapter bolts, flexplate bolts, shifter bolts. If you can see a bolt head/nut, try to tighten it. Even if you did that a week ago...do it again and be more thorough. A bolt can actually be broken and still attached and in place as if good to go.

 

[Bent77]

I have seen flex plates cause this if installed backwards and putting tension on the trans pump

 

[jeff in co]

What is the engine ?

I had a 400 that somebody put a 350 flex plate on had a small but distinct vibration took for ever to figure it out. Finally did, changed the flex plate sold the Blazer. Crankshaft broke in half not to long after that. Guess it did not like being balanced after not being balanced for so long.

It has a 350 in it but from the numbers, it appear to have been a 1981 block from a C30 truck of some sort. I have no idea or history on the engine as it was there when I bought it. It changed owners several times so I have no idea who did it and if it was quality or not. I've touched or rebuilt pretty much everything else.

Tranny - Tranny shop
Front axle - Rebuilt myself (outer part, not gears)
Rear axle - New GM gears by local shop with Eaton E-locker
t-case - Myself with JB Conversion's SYE
All driveshafts - Tom Woods and new spicer joints up front

I'll try running around and tightening bolts, checking for cracks, etc. Appreciate it Zeus