vibration

[jjones]

I have a 259 in my M5 truck, with a SteelTech adapter and a GM TH350 automatic transmission. This combination has performed perfectly for the last around 1,000 miles. Coming home on the freeway today, however, I started to feel a slight vibration. I got off on the surface streets and slowed down but by the time I got home, the vibration was worse and the real seal was leaking more than usual. Vibrates stopped in park, too, and feels like the torque converter is loose. I pulled the torque converter cover--all bolts are tight and the flex plate seems to be running true.

I suspect the flex plate is loose, or something in the front of the transmission is going kaput. I would appreciate any suggestions before I have to pull the engine/transmission for a look-see.

Thanks

jj

[KGlowacky]

Check the drive shaft. Look for a lost weight that balances it. Sometimes they fall off and it will create a bad vibration all of a sudden. Good Luck.

[bige]

Check that the yoke is going far enough into the tailshaft, if it's not it might have worn the bushing and the reason the seal is leaking is the the yoke is bouncing around along with the output shaft.

Ernie

R2 R5388

[sbca96]

Could be the start of a torque converter failure. This a used trans?

Tom

[hank63]

If the vibrations continued when you were stopped and in "P", it can only be a rotating part. Engine, torque convertor or engine accessories like pump, alternator, etc.
/H

[Roscomacaw]

Vibrating in park would indicate the driveshaft's not at fault. UNLESS, in it's demise at speed, it managed to damage something that affects balance while in Park![xx(]

Miscreant at large.

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe
1957 President 2-dr
1955 President State
1951 Champion Biz cpe
1963 Daytona project FS

[jjones]

I took the alternator/water pump belt off--still vibrates. Also the rear seal of the engine leaking suggests something back there is causing the vibration. Driveshaft looks fine and has its weights intact. Torque converter is new and transmission was completely rebuilt including bushings and pump. I rebuilt the transmission myself, but it has worked perfectly for 1,000 miles and still shifts correctly. I suspect either the torque converter or the flexplate is failing but was really hoping one of you more experienced Studebaker mechanics would tell me something simple and easy to fix was wrong. On the bright side, I needed to tear it down to paint the firewall and inner fender panels. Guess this is the time.

Thanks

jj

[GTtim]

I gather that flex plates crack in a circle, so it could be that it is broken and you can't see it from the limited access.

Tim K.
'64 R2 GT Hawk

[Roscomacaw]

Not necessarily, Tim. I've seen them crack between the bolt holes and I've seen them crack in a radiating pattern.

I hope this isn't the case with this engine, but I also have heard of a couple of 289s where the crankshaft BROKE and caused vibrations but was STILL driveable!!![:0] In one case, a young gal was using the car (a 58 Packard hardtop) to go back and forth from her home to college. She drove it like that for over a month before her dad found her a different Stude to drive.

Miscreant at large.

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe
1957 President 2-dr
1955 President State
1951 Champion Biz cpe
1963 Daytona project FS

[GTtim]

I didn't mean to suggest that that was the only way the flex plate could break. I just wanted to suggest that it may not be possible to see that it is broke without taking things apart to get a better look.
As others have mentioned, the problem has to be with the rotating engine parts, it would not be a good thing to find that the problem is with the crank.

Tim K.
'64 R2 GT Hawk

[hank63]

A long shot, admittedly, but check your engine mounts.
/H

[PackardV8]

I would have guessed flexplate, but you said it is running true. If the flexplate was causing the vibration, you should see it oscillating.

Since this is an engine swap with an adapter, and GM uses integral bell-housings on their TH350s, did you find any way to dial-indicate the setup?

Dave/SteelTech is to be commended for taking on production of Stude modified parts no one else is doing and selling them affordably. However, some of his methods are from the Studebaker Johnny/blacksmith era rather than modern CNC. One adapter kit I bought from him some years back was not flat and had to be ground on both sides before I could use it.

My money is on improperly registered assembly causing internal failure of convertor or transmission.

thnx, jv.



PackardV8

[sbca96]

I got one of the Levesque adapters years ago back before he became the
SteelTech name. I didnt have any problems lining up things. I guess
one question I have for you, is how well did you pin the setup with a
couple dowel pins - or .. did you?? Daves setup uses a self aligning
aluminum centering device, that positions the adapter plate, but it
requires that BEFORE you remove it, you drill some dowel pins into the
block through the adapter. There are fit issues involved, so you can
not just drill a hole, you need to make sure its TIGHT in the hole. If
you didnt anchor the plate with dowel pins, no matter how tight you got
the bolts, its gonna move over time. Just another thought.

Did Dave ever end up adding a through hole to the torque converter bolts
to torque them to spec? When I bought his setup, I noticed that it
wasnt possible to do that, and I used a hole saw to drill the plate at
the right radius, giving an access hole for the socket. I let him in
on this after I did it, that was about 12 years ago???

Tom

[jjones]

Got the engine out and the trans off yesterday. Flex plate looks good. I will have the torque converter checked if that is possible, or replace it. I suspect the torque converter rather than set-up as the thing ran fine for 1,000 miles, and the vibration came on rather suddenly. I was running a little over 80 mph (typical freeway speeds for Tucson) but with 2:76 gears in the rear, she was not overrevving.

Tom, I did use the aluminum centering device, and did pin the plate to the block. The only problem I had with fit was one of the top studs tweaked a bit when he welded it. I tapped it a couple of times and the transmission bolted right up. I just reinstalled the centering device and checked the setup--seems perfect. And no, he never added a hole to torque the torque converter bolts. That's a good idea and I will do it before I reassemble the thing. I used the "two grunt" method before, but it was still tight.

I have been building and driving street rods for over 40 years so figured I had probably screwed up or broken about everything it was possible to screw up or break. This one is a first, however. I appreciate all of your suggestions.

jj

[sbca96]

Sometimes a torque converter can just "go". If you bring it to your
local college, they MIGHT have a trans dyno/tester. I know that SBCC
has one. They can hook up the trans and run a test out of the car! It
will eliminate the Steeltech setup, the car, driveline, and ash tray!

I am really surprised that Dave never added that. He seems like he
would be more open to feedback then that! If you are concerned about
any debris getting through the hole, then use a standard size core
plug diameter hole saw, or a body bolt hole plug. Here are a few pix.





I drilled a 1 inch hole about 5-1/2 inches from the centerline of the
crankshaft.



About 5 inches from the bottom of the plate (this assumes his plates
are ALL the same size!)



And about 3-3/8 inches from the side of the plate (again, this assumes
his plates are ALL the same size!)



Tom