'74 Triumph Stag - 10/07 - Around Europe with New Owner!

Well, I have tried to proceed further with the vibration hunting, so I started to work my way through other areas.

One suspect area was the gearbox mounting and crossmember. The bushes were partially missing in addition to being over tightened. Also the gearbox mounts were not in great order (one was quite soft and both were distorted as a result of being 'made to fit). The new bushes are on the outside.



In their distorted form they fitted the crossmember quite poorly like this:



So a new bracket was made:



As you can see one bush was missing (about a 1/4 of it was left on the car, and none of them had their nylon spacers with the bushes all being deformed and playful affairs).




New bushes were purchased. Only a slight difference...:



After all that, how does it drive? Still bloody vibrates as soon as you hit 50, although as before it vibrates slightly when you put your foot down from about 30mph onwards.

Time to look at the gearbox flange (I am sure it was tight before and it does look as if it is loose so I shall attempt to tighten that) and to try getting the propshaft balanced. Balls.

To cheer me up, I decided to whack on some new wheels onto the car. The vibration has gone down with this but the core vibration is still present.





The bumper was off so as to remove a snapped bolt from before me buying the car.

Damn this thing.

Believe me, dropping the car has been near the top of the list for quite some time, but other issues (I.e The vibration) take priority over it.

Regarding that, my mojo has been on the ups and downs on this car. Ups when on the country roads cruising down at 50MPH or driving in town, down when I see the oil marks from the leaking diff on the drive in addition to a clonking exhaust (not hung up properly on the subframe and blowing in places (wrong clamps), or on a dual carriageway (where I near enough have to) doing a sedate 55MPH thanks to that sodding vibration.

On the plus side I seem to know lorry drivers better and all that headlight flashing business LOL.

So with that in mine, and the sun being out, I figured it was time I made a start on correcting that, and so I proceeded to take away various parts that would allow me to drop the subframe down, so as to change the diff and extension housing.

Before I went about doing any of that, I changed a tired universal joint for a GKN item in the driveshaft. Whilst it made part of the drive smoother, the vibration was still there (if anything it is noticed more as the car becomes a smoother drive).

Off first was part of the exhaust system (it passes through the subframe itself (round holes are visible in the front part):




And it's off!


Next was the propshaft. Remember this speedo ring?



When Rob and I drove this car with the gear selector removed so as to see how the gearbox and propshaft were behaving we noticed that the speedo ring threw out the propshaft about 1/2 to maybe 1mm outside of the true. In the vibration zone the propshaft did not shake or vibrate so it was not seen as a cause for concern. But on the basis that it could cause some issues off it came.

This turned out to be fun, with screwdriver not even budging the ring off the propshaft flange, so I had to resort to other measures:



And the ring is off! I have indexed everything just in case but it probably is not necessary (it might even improve things LOL). I did notice that the holes for the bolts were larger in the ring but again I did not see this as a cause for concern.



The prop shall now be taken back to Dave Mac Props to see if it is out of balance.

Whilst I took that off, it appears that my nosecone bearing is not in the best of health with some play present, and well, being the source of the leaking gear oil. Later on the in the week the subframe shall be dropped off and the new diff and nosecone (reinforced with a new extension housing (nosecone) bearing) shall be fitted once the coil springs, brake flexi hoses and handbrake cables are removed.

Another thing I noticed was that the diff when turning one of the output flanges (with the other output flange and input locked off) is that when I turn it to get rid of the backlash it stops (like the other diff (less is present in the other) and then it creeps on slightly more to another stop. When reversing and turning (and sometimes when taking a tight corner when going forwards) it does seem to bind slightly. Whether this is the UJs (they are all free) is another thing, but again we shall see what it's like.

Good luck Chas! Any chance it will be done before the housewarming There are some lovely roads through the Cotswolds on your drive down

Note that the quill shaft bearing is a sealed-for-life greased ball-race. It is not supposed to see the diff oil at all. In fact diff oil, leaking from the front seal washes the grease out and causes the bearing to fail. To stop the oil leak you have to fit a new oil seal into the nose of the diff itself. Many will tell you get the original type leather seals but in my experience the modern double-lipped rubber ones work much better. Getting the old seal out (especially the leather ones) can be a trying process!

Just a suggestion, but on re-assembly, why not try running the car up to speed on axle stands before you connect up the driveshafts (do put oil in the diff first!). Then you will know, if you get still vibration, that it has nothing to do with the driveshafts or rear wheels. You could also try balancing the prop on the car with two jubilee clips, which is the only way I've ever been able to eliminate propshaft vibration on my Vitesse.

If you find you are vibration-free, then fit the driveshafts without the brake drums and try again.

Good luck!

Nick

I meant that you should do this with the prop in place and spinning the diff, but without the shafts. The prop is a strong suspect. I think you have changed this already (?) but I've been there with my Vitesse, which vibrated whatever I did (new orientations, new joints even complete new prop) until I balanced it on the car with jubilee clips.

On my PI I had a nasty vibration which was largely cured when I discovered (by chance, when refitting the gearbox) that the front prop UJ flange had the bolt holes and centralising spigot on considerably different centres (like 3mm different!) with the result that you could either have the spigot fully drop into the recess in the gearbox flange or put the bolts in - but never both. Witness marks on the gearbox flange suggested that although I wasn't the first to spot that there was a problem, I was the first to figure out what it was (took a while though!). So don't go assuming any of the parts were made right in the first place......

Another thing to watch out for is whether the hub flanges run true. They are so damn tight on the stubs through the wheelbearing that they often get injured on removal causing wobbly wheels and bad vibes.....

Nick

Brilliant news Chas, sure this must ahve been getting you down. Such a great lloking car as well. I'm sure you've said somewhere, but why the speedo trigger wheel. On a kit car cobra I had I'm pretty sure it was similar to what's on my push bike? Might be an easier option?

Great stuff! Those wheels really suit it.

Hurray and well done for sticking with it! And sorted in time for summer, a Stags natural environment.
I think you don't need a speedo for a MOT and if you need to know how fast you're going, use a Sat Nav?

Number plates looking really smart Chas!