vibration

[mdelapp]

I just had some tranny work done on my 53 commander hardtop. Fixed the downshift and searching for gear problems. I now seem to have a little low vibrations that becomes appareent at about 50 mph and stays as I get to 60. don't drive much fastger than that. Might this now be a driveline issue? I dont know that he removed the drive line during repair. I am taking it back to him to adjust some shifting linkage problems and want to ask or suggest what may be the problem arising that might now result in the vibration. I have a hard time thinking of driving to South Bend with the vibration. Any suggestions as to what to look for may make me appear a little more knowledgable when I meet with him.
Thanks so much
Mike DeLapp

Mike DeLapp
Barrington, IL
53 Commander Hardtop

[sbca96]

Could be a universal joint, or that center bearing on the two piece
driveshaft needs grease or rebuild. There are a lot of things that
can cause a "vibration", sometimes an exhaust pipe can resonate on a
part of the frame at a certain RPM/load/speed, & cause a LOUD noise.
Any contact with the frame can transfer to the floor .. vibration. Do
you feel it in the steering wheel?

Tom

'63 Avanti, zinc plated drilled & slotted 03 Mustang Cobra 13" front disc/98 GT rear brakes, 03 Cobra 17" wheels, GM alt, 97 Z28 leather seats, soon: 97 Z28 T-56 6-spd, Ported heads w/SST full flow valves, 'R3' 276 cam, Edelbrock AFB Carb, GM HEI distributor, 8.8mm plug wires

[bradnree]

The first thing I do is get the tires rebalanced as I did before the trip to Omaha in a 1960 Lark. It had a high speed vibration and I have experienced this before over the years with several cars. This is a good cheap place to start, and also try proper tire pressure.....Brad

[Tom Bredehoft]

I've had my '53 coupe worked on twice, once by a reputable Stude mech and once by a Retired Tranny mech. Both times the center bearing support was centered in the mount, not offset. The first time they drilled new on-center holes, the second time they used them again. Each time there was a tell-tale rumble at moderate speed. This can be adjusted without removing anything but the bolts on the hanger.

Tom Bredehoft
'53 Commander Coupe
'60 Lark VI
'05 Legacy Ltd Wagon
All three Indiana built OD cars

[mdelapp]

Thanks for the info.
The car was smooth as silk before the tranny work so I discount the wheel balance. Took it to him today with a printout of your responses and he understood that the drive shaft has to be balanced to am confident he will sort it out. Weather a little chilly and no car shows soon so I told him to keep it and drive it until he was satisfied with the smoothness. Hope it is done in a couple of days so I can get back to easy things like painting instrument shrouds and fixing the light that illuminates the gear selection.
Mike

Mike DeLapp
Barrington, IL
53 Commander Hardtop

[bradnree]

I had a mechanic work on my '31 Ford street rod because I had a terrible high speed vibration. We changed the yoke and joints and still had the problem. 4 wheels balanced with weights on the inside or outside of the wheel or wherever needed and it was fixed. You are right it's probably the tranny.....Brad

[bige]

If you haven't isolated your vibration I have a suggestion. I have an Avanti that I put a 700R4 trans in. I've been experimenting with different governor weights and springs and I would have to drop the crossmember to make the change. Most times I wouldn't notice anything different in the drive except the last time I got a strong vibration at about 75 MPH. At the same time I noticed a rattle coming from my shifter plate and the shifter seemed to be off center. So I loosened the trans mount bolts and moved the trans to the left and tightened the bolt. Had the car up to 90 and the vibration was gone.

The moral of this long winded story is that in the course of checking pinion angles the lateral position needs also to be checked. The amount that I moved the trans to cure the problem was probably no more than 1/4".

R2 R5388

[r1lark]

quote:Originally posted by mdelapp

Thanks for the info.
The car was smooth as silk before the tranny work so I discount the wheel balance. Took it to him today with a printout of your responses and he understood that the drive shaft has to be balanced to am confident he will sort it out. Weather a little chilly and no car shows soon so I told him to keep it and drive it until he was satisfied with the smoothness. Hope it is done in a couple of days so I can get back to easy things like painting instrument shrouds and fixing the light that illuminates the gear selection.
Mike

Mike DeLapp
Barrington, IL
53 Commander Hardtop

Mike, a couple of thoughts. The shop manual shows what bolt holes to use for the center driveshaft support, based on the body style (ie, C, K, F, etc). Also check to make sure the engine is installed in the correct holes in the motor mount frame brackets, the shop manual will tell you which ones (at least it did for my Champion 4 door).

Another thing to check are the insulators between the center drive shaft support and the center crossmember. These should hold the center bearing support 'snugly'......in other words, if you can grab the center support and it is 'loose', you may need new rubber cushions.

My '54 Champion had a low speed vibration (and chattered really bad starting off) and the center drive shaft support cushions were most of the problem. The center support was also in the wrong holes, but I changed this before I started driving it.

The other responses took care of my other thoughts (center driveshaft support bearing, driveshaft balance, how the two driveshafts should be installed in relation to each other, tire balance, etc).

Paul

Visit The Studebaker Skytop Registry website at: http://hometown.aol.com/r1skytop/myhomepage/index.html