Drivetrain Problems!! Assistance Required!

[Eugene]

Hi guys. I'm new here, Have been to the website quite often only for troubleshooting.
I have searched past threads trying to get a reasonable explaination, for the difficulties that
I am experiencing with my truck. well I'm not one to run around the bush so I'm going to get striaght to the point

Truck Specs:
1985 Chevy Blazer K5
v8 305
10 bolt front and rear 3.73 AT

As for the type of transmission I have and other info I'm not very skilled in the Identifying
of the other parts. (if info is required regarding a part tell me how to Identify it and I'll get the info to you a.s.a.p)
my Truck is used for street driving, I was driving down the road one day and had some young girl, run into the rear end of my truck with her little sunfire, she hit and there appeared to be no exteroir damage to my truck, we said no more about it. 1-1.5 weeks later I started to experience a slight vibration
in the truck. I thought nothing of it cause the suspension is already shot on it and I feel every bump in the road as it is. well day by day went by and the vibration became worse and worse. this vibration Only happens on acceralation and can be felt throughout the whole truck so I figured it was the u-joints, which turned out not to be the case. I decided that I would
open up the rear diff cover ONLY and once I had the oil drained, I saw a whole tooth that was sheared off of the pinion gear (I think that's the gear that connects to the yoke). Having figured that, that was the cause of the problem, I removed the tooth and filled the case back up with 80w-90
took it for a test drive, and the vibration was gone, but suddenly there was a sound like something (a tooth?) still in there, just being bounced around. (note* the front diff cover hasn't been opened yet)
2 days ago the truck started to shake very violently,when ever the truck is acceralating, but it appears to be fine when the foot is off the gas, this is while the truck is in forward motion. When the truck is being reversed the opposite is true when in reverse accelaration the truck is fine and shake free but once the foot is removed from the gas the truck begins to violent shake (all this takes place while the truck is in 2wd) But while the truck is in
4wd the front axel vibrates slightly ALL THE TIME (accelaration, or when foot is removed from the gas) The Only thing that is common between the two is that sound of something bouncing around in the rearward area. Difficulty has been incountered in identifying the location of the sound ( I think Rear Diff case).

NOTE: Almost everything on this truck is original including the drive train and it has only 87,000km's on it (around 56,000 miles) so it still has some life in it
also it was my first Mode of transportation I ever had when I was in college and has always been there for me I would like to keep it alive and running. I'm also mechanically inclinded, as I am an Aircraft Maintenance Enginneer.
just Trucks and cars are alittle different than their airborne counterparts, so I figured that no better place to ask people for some tech advise then a bunch of people that maintain this type of truck for a hobbie, as well would have
a much more extensive troubleshooting Catalouge than I would. (the little mental list of problems and symptoms that have been experienced over the years).

I Thank you in advance for Your assistance.
Eugene

 

[Emmettology 101]

first off check your u-joints. Stick a long screw driver in the open voids and see if there is any play where the center cross and the caps connect.

Next check you rear pinion for play. See if you pinion bearings are bad and see if the pinion nut is loose. That would casue the rear vibes. It wouldn't hurt to also open up the rear again and see if there is anymore teeth in the bottom of the diff.

On the front, check your u-joints and pinion up there. Also check your driveshaft for play. The CV joint will wear and cause vibes. The slip joint on the shaft will wear and cause vibes also...

check that stuff and let us know!

 

[resurrected_jimmy]

once 10 bolt axles start spitting out pieces they don't tend to get better own their own

 

[Chevy305]

Ok, so you lost a tooth on your pinion gear and you wonder why you are still having problems?!?!

You got to get a new ring and pinion gear set man!
I'd have the front and rear axel rebuilt and all the ujoints replaced

 

[beater_k20]

first thing is first, get it to a frame shop or body shop and have it looked at. it may cost you a bit to have it looked at (i'm assuming no accident report filed, mistake!). if your frame is tweaked it could easily effect the trans, transfer case, rear differential, and any other number of components. before sinking any money into your drivetrain, make dead sure your frame is still straight. failure to do so could result in repeated failure of the new parts installed to fix its current problems.

 

[Eugene]

just to clairfy something, I'm not currently driving the machine until I can find a replacement pinion and ring, I noticed today when I took the pinion out that there may have been an error in the heat treatment of this part and since I'm going to assume that the pinion and ring would have been machined together that there may have also been an error in the heat treatment of the ring as well, assuming that they were machined together.

Emmettology 101----> I had opened the rear again to find no other teeth, the ujoints front and rear are in good working order as well as the pinion bears and nuts. front to back. The constant velocity joints are fine also.

but some progress was made today the "sound" was found to be comming from the transfer case. Me knowing myself I would not know where to begin to troubleshoot a transfer case, without proper consult.

I also think that having the frame checked, is a brilliant idea, and I would like to thank all the people that replied with helpful information,

Eugene

 

[goldwing2000]

I've seen rear-end collisions tweak driveshafts, too.

Chock the front wheels, lift the rears off the ground, start the engine and let it idle in drive. Look under and see if the driveshaft looks like it's "bouncing".