TR2/3/3A TR3A vibration - looking for ideas

[TFR]

Installed a newly rebuilt engine while painting the car. The engine is running fine and seems to be okay.
Here's what happens..
For a back ground the only thing changed is the engine. The tires, wheels and their locations, the tranny, drive shaft, ect. the same place and part.

At some revolutions the cars shakes. I thought it might be the exhaust hitting the frame, it isn't. Then I though may be the engine was missing causing an miss vibration, can't find any problems with the plugs, carbs, etc.. Cam has no warn lobes. Compression is equal at 120 lbs.
Here's what I've tried... I get up to 45 MPH. and the shut off the engine and coast it vibrates badly all the way until the car stops. Thought it might be the pilot bearing being loose but I shut off the engine put it in neutral which should stop the clutch from turning. So I don't think that's the problem.
Do you think the back half of the tranny could have a problem? Bearing, alignment, ???
Any other ideas would be appreciated...

 

[Adrio]

I had a similar vibration problem with my TR4A and it drove me nuts. In the end it was a combination of two things (always makes for more fun trouble shooting) - the front wheel bearing were loose (just a bit but it made a difference) and the inner tie rods were loose (again just a bit but it made a difference). Removing either issue did not make the problem much better, in fact I hardly noticed and thought I was being "optimistic" but removing both issues made it go away.

In short look for loose wheels of some sort.

 

[TruCraft]

With engine off and in nuetral it still vibrates.
I would jack up the car & check the U-joints, drive shaft, wheel bearings, tires and wheels.
Hopefully it's something simple like a loose wheel.
Lyle

 

[prb51]

So it appears to be other than a harmonic at a specific speed.
What else was removed with the motor?
Is there a new vibration when at idle/stop thru the rpm range? If not then your crank/flywheel/clutch etc. shoulkd be ok.
I'd check all rotating mass as described above specifically your driveshaft. Was the driveshaft oriented exactly as it was prior?

 

[TR3driver]

My first guess would be a tire that failed (got a "flat spot") while you were working on the engine.

Another possibility would be the driveshaft flange not properly seated onto the gearbox flange (assuming that is where you separated it to R&R the engine).

Could be lots of other things, of course, but the fact it happens with the engine off and gearbox in neutral pretty much eliminates the engine, clutch and gearbox input shaft (assuming you also released the clutch pedal during the test).

Running on jack stands is a good way to look for driveline problems, but be very careful. With no weight on the suspension, any balance problems are exaggerated to the point it could possibly shake the car right off the stands!

 

[TFR]

Thanks guys...

I don't think it is the front suspension since it is new and hadn't been removed or reworked since the engine change.
I tried another drive shaft and it still has the same shake or vibration (more like a shake)
Randall, I am inclined to think it might either be the back half of the tranny having an issue or like you suggested the drive shaft mating the rear or tranny flange. Will check those this week end. (getting cold again so no test drives)
Also, Randall you asumed correctly I did have the clutch released. Thought it would test the back half of the system by shutting off the engine and putting the car in neutral with the clutch peddle up as I coasted down a hill.
What worried me is when I installed the engine and mated the tranny the input shaft seemed to be slightly (and I mean slightly) loose in the pilot bearing.

Any other ideas? keep them coming..

 

[NickMorgan]

So many things can cause a vibration on TRs. They have plagued me with most of mine and usually took a long time to find out what was causing them.
One thing to consider is that these cars like to through in all sorts of problems when you least expect them, so there may be some issue that has coincidentally occurred at the same time as you changing the engine. However, I would certainly go through everything that you would have loosened or changed during the re-paint and new engine installation.
An out of balance prop shaft is a likely source. If you have disconnected it and then replaced it you may not have used the original bolt holes on the flanges.
Wear in the sliding joint may now be more apparent after it has been pushed and pulled during the installation.
Possibly the pinion flanges may not be as tight as they should be.
I think that it would certainly be worth putting the car securely on jack stands and then crawl underneath and twist and pull on the prop at either end. Check for any play in any direction at the pinion flanges, UJs and sliding joint.
Check that the gearbox rubber mount is OK. If it had been marginal before the engine work it may now have given up.
While the car is up there spin all of the wheels by hand and check that the wheels are all perfectly round (I have had four distorted wheels on my three TRs over the years, which turned out to be the main cause of any wobble or vibration on the cars). Also push and pull the wheels in all directions to check for play in the wheel bearings, steering, etc.
Stick a bar under the front wheels and just check that none of your new ball joints or trunnions have any play in them.
Good luck and let us know what you find.

 

[Silverghost]

No idea if this is helpful or even close but reading the previous post made me think about the engine mounts. Presuming you put new mounts in all around, this MAY have shifted positioning and alignment ever so slighty. Building on this premise, now the engine/trans is not quite where it used to be, so the drive shaft isn't quite where it used to be, the u-joints, etc. Might be an overall alignment thing which isn't readily apparent to the naked eye? And as previously mentioned, is the driveshaft back in the same position and balanced. I maybe completely wrong here, just thought I'd put my 2 cents on the table.

 

[newmexTR3]

Check that the gearbox rubber mount is OK. If it had been marginal before the engine work it may now have given up.

I second checking this out this- I had a strange vibration in mine that suddenly appeared. Turns out the transmission mount had cracked down the middle, letting the engine and tranny sag a little, which then led to a whole host of problems.

The rubber on mine was fine- the metal itself cracked, so take a careful look at it.

 

[angelfj1]

Larry: some time ago (you can do a search) there was a discussion about vibration in sidescreen cars. Triumph had a lot of complaints about this and different methods were tried to solve the problem. One idea was a vibration damper. See attached photo. This was hung from the exhaust pipe. Sorry, but I do not have any photos of this installed in a car.

My opinion is that you have a simple balance issue. Did you have the drive shaft balanced? What about wheels and tires?

 

[TR3driver]

Frank, I believe that weight went on the tail of the OD housing, rather than on the exhaust pipe. At least that's where I found it, on a relatively unmolested TR4 that I once parted out.

I also don't think it was intended to solve anywhere near the kind of problem Larry is describing (which perhaps just means I don't understand the question). Rather with the advent of the "more refined" TR4, people started complaining about "buzzing" of the shift knob at certain engine/road speeds. Both the weight and the brace for the shift cover were introduced to reduce that. But AFAIK the factory never fitted them to TR3s.

I left the weight off when I installed that OD in my TR3A.

 

[TFR]

A little more history. In 2006 and 2007 I completely replaced every bolt, rubber part and, seal on the car. I had the drive shaft balanced and U joints replaced. This year I replaced the engine with a true TR3 engine (mine was a TR4). Not that I didn't like the last engine but it had leaks in the sleeves allowing water to seep into the oil. So instead of fixing it and then reinstalling, I replaced it.

The problem I'm having is more than a vibration it is a "thunk" , "thunk" , "thunk" as you are a certain RPMs. It continues until stopped. Even during a coast as stated in the previous posts. Seems to be a major issue.
My suspicion is still either with the tranny, flanges or rear end. Like all have said, put the car safely on jacks and give it a run. Hopefully the problem will show itself. If not, I'll have to dig deeper in to the car by removing the engine and tranny. (again :-{ ) Going to try it as soon as possible. Need to resolve this issue before the driving season starts.

 

[TFR]

Guys, I put the car on jack sands and put it in gear. The drive shaft wobbles even at idle speed. I cahnged the rear drive shaft flange and it still wobbles.
Next is the front.
Randall you mentioned the flange not evenly mating with the drive shaft might cause an inbalance. If the flange doesn't mate with the drive shaft (pardon my ignorance) why would that cause a wobble. I thought the U joint would still make it stay true? Does it cause it to be out of balance?
Also, if it isn't the flange or drive shaft what's the chances of the output shaft being bent? Could it be bearing wobble?

 

[TR3driver]

If the flange doesn't mate with the drive shaft (pardon my ignorance) why would that cause a wobble.

Each flanges has a ring built into it's face, that should mate with the matching flange to ensure that they are properly aligned. Usually it's no problem, you just stick the bolts in and the rings pull the flanges into alignment as the bolts are tightened. But if the rings are damaged, or there is a chunk of FOD left in there, it's possible for the flanges to remain misaligned with each other.

Since you can see the wobble at idle, it's almost certainly not just a balance issue. I would be trying to look at the edges of the flanges, and the driveshaft body, to see where the wobble is introduced. If, for example, the rim of the transmission flange also wobbles, the problem must be in the transmission (or the flange itself). But if that rim runs true and the front driveshaft flange does not, then the joint between the two flanges is suspect. And so on, all the way to the differential itself.

 

[TFR]

Randall, As you know it's hard to see the front flange with the trans cover on. I think I may have to pull it off and then see what happens.
I have a nice small lathe (Logan 10" from 1943) and I can put the flange in the chuck and see if it wobbles.
As for the drive shaft, this is the second that I used and both had the wobble.

Will update as I discover more findings.

 

[Don Elliott]

Larry - I suggest that you unbolt the driveshaft from the rear of the transmission and slide the bolting flange out of the way - towards the rear on the splines. Then rev the engine and see how the vibration is. If it's gone, you have traced the problem to the driveshaft. If the vibration is still there, it's probably the rear gearbox mount.

 

[BIBBER]

Man this is better than a good mystery..I was going to mention new mounts but it was already suggested....Larry keep us posted on progress..

 

[TR3driver]

Randall, As you know it's hard to see the front flange with the trans cover on.

Not my recollection at all. The edge of the flange shoudl be readily visible from underneath the car, between the rear crossmember and the center section of the frame. IIRC the front driveshaft flange is slighly under the fixed part of the body, so not as easy to see from above even with the tunnel off.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I have a nice small lathe (Logan 10" from 1943) and I can put the flange in the chuck and see if it wobbles. [/QUOTE]I think you're missing my point, which is to check all these places in situ.
IMO it would be much better to check it first still attached to the gearbox. Even if your lathe is equipped with a splined shaft to mount the flange (somehow my 48 Atlas came without that option

), checking it while mounted to the gearbox will also show you a problem in the gearbox itself.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]As for the drive shaft, this is the second that I used and both had the wobble. [/QUOTE]This reminds me of the old saying about getting parts from the junkyard ... "I've already got a used one."

 

[Don Elliott]

Some TR4s developed a strange vibration similar to what you're describing and S-T designed a "lump" that solved the problem. It went around the aluminium tail just in front of the output flange with some odd looking support links and finally the "lump". This consisted of a bolt in the center with a rubber sleeve and then another metal tubular sleeve (somewhat like a "silent block" and this was pressed into the "lump". The "lump" was bolted and clamped below the tail of the gearbox housing just in front of the flange for the output shaft.

 

[TR3driver]

Don, Frank posted a photo of that "lump" above.

I still don't think the problem it addresses bears any resemblance to Larry's problem.