[Robintr6]

Ok guys next problem. Have a noticeable vibration my my 2ltr GTV(1972). As I've posted this car has been off the road for 20yrs and is just back on. Anyway had a very bad vibration which got worse as she has been driven from the drivetrain. Anything above 2000rpm to about 4000rpm , goes thereafter. Inspected the usual suspects, doughnut and, gearbox mounting and UJ's. The gearbox mounting just behind the doughnut had torn (the one that goes thorough the back of the box) so replaced it (not easy). Anyway now much better but not gone (vibration). Its definitely from the drivetrain. The UJ's look good as does the doughnut and so does the central bush (which sits in a rubber mount about midway along the transmission). Given the above I am wondering if the gearbox mount only went because of the strain caused by something else. However given it all looks ok I'm a bit stuck as how to proceed. There is a little play in the central mount , ie I can move the prop shaft a little (2mm) but dont know if this is ok or not. Otherwise it looks fine.

Appreciate soime ideas....

BTW have balanced the carbs as advised and shes running much better so thanks for that.

 

[spiderserie4]

Common causes of vibration, as you suspect are

worn donut (giubo joint) - double check this would be my first thought.
UJs - you do not want to feel any play in these.
Worn centre carrier bearing/bush
Loose flange bolts on prop.

If the gearbox mount needed replacing (you put it in the right orientation I presume?) it is often caused by worn engine mounts......have you checked these? (one tell-tale sign, apart from the obvious visual check if they are squashed, is when your sump is not dead level) - engine has a natural tilt to the right when seen from the top, but the sump is/should be level.
Did you replace the gearbox mount with a poly mount perhaps? many issues of vibration reported when using poly here.

Also possible that a PO separated the propshaft and did not mark it and put it back 180degrees out. That would put the Prop out of balance (did you split it to do the gearbox mount, if so, did you mark it?)

Grease the sliding joint (often overlooked)

 

[Robintr6]

SpiderS4, thanks for the thoughts. OK gearbox mount , the rubber central shaft for the bolt is nearest the ground and the wing shaped rubber surrounding it bending upward. Thats how the old one was ???assume thats OK. The Doughnut looks fine with no perceptible wear at all. Engine mounts also look good and yep engine and sump as you describe, UJ's no movement that I can see albeit the rear looks to be newish (no grease nipple and looks newish). Central mounting bush also looks OK but there is a bit of movement in it ....I can just move the prop shaft a tiny bit, is that how it should be???

 

[Robintr6]

Ok forgot will check the prop shaft, are there marks on it ??

 

[spiderserie4]

yes gearbox mount has bolt hole lowest to ground
central mount will have a bit of movement when you push up or pull down as it is in very soft rubber, but should not have any clicking/movement in the bearing itself.
Not too sure if props were factory marked, I sort of doubt it, as everyone mentions how important it is to mark them when undoing them!

and do grease the sliding joint (this has a grease nipple), just in case it hasn't been done.

 

[Robintr6]

Ah, HA....just been down there again, the UJ at the middle has play in it, quite a bit so will replace. Didnt notice before as hadnt really got under there. Just goes to show how easy to miss. Car on 4 axle stands means I can get a really good look at. Thanks

 

[spiderserie4]

now that you found the wire, did you connect it up and does the oil pressure light now work?
Glad to hear you found a worn UJ, that will probably cure the vibration problem.........or at least be a big part of it!

 

[Robintr6]

SpiderS$, you have me mixed up as I havent an issue oil pressure(yet). Mind you I now know where to look for both the light and gauge thanks to the relevant thread. I'm hopeing that having replaced the bush at the end of the gearbox and the iired UJ that vibration will be a thing of the past.......Next up are carb(s) rebuild and calipers but at least they should be relatively straightforward.

 

[Robintr6]

Guys

just an update. Replaced the knackered bush at the end of the gearbox (near the propshaft) and the worn UJ on the propshaft (bit of a big both of them to replace lying on your back )but for £30 for the pair my drivetrain is now without vibration. So we have a smooth running car HURRAY. Next up is a carb rebuild and caliper rebuilds. The brakes work fine but given their role and being unused for 20 years its a small price to pay for peace of mind.

Thanks all for your help

 

[spiderserie4]

glad you found the cause!

 

[anglospider]

Hi Robin, I have no experience of propshafts but mine needs the centre bearing replacing. Rather than mess it up I have acquired a s/h one to refurbish. If all goes well I will put it on the car, if it doesn't I will put it down to experience instead

Question, how easy/hard are the UJs? Any tips?
The centre bearing needs to be pressed, I will prob get a local garage to do that bit as I don't have a press.

 

[Robintr6]

no probs. when you say secondhand one I assume you mean propshaft. in any event here's my experience. get the car up on 4 axle stands high as you can. the UK's need 2 x 13 mm open spanners and some muscle. Tap the spanne with a heavy hammer to break the lock and ensure you have marked the shaft and knuckles so you refit as they were. its a balanced shaft. Remove the one at the diff end first then the one in the middle. then out comes the back half of the shaft. then undo the doughnut coupling at the front again marking both shaft and doughnut ready for reassembley. the middle bearing carrier is 2 nuts and should then come out easily.I believe you can buy a complete bearing in the rubber housing (classic alfa) thus avoiding and grief with that. replace I'm reverse order. If you can get a helper so much the better as the prop is heavy but I did manage on my own. really check the Uj's as they are cheap and you don't want to have to revisit for them.they take 5 or 10 mins each. Am just up the road from Milan now being very Alfa. let me know if you need anything else and good luck.

 

[spiderserie4]

I have no experience of propshafts but mine needs the centre bearing replacing. Rather than mess it up I have acquired a s/h one to refurbish. If all goes well I will put it on the car

won't you need to get that balanced?
I can't imagine just putting a prop from one car onto another and driving off vibration free...even if all the bearings/UJs etc are new.

 

[anglospider]

Thanks. I can get the shaft off but I was more concerned with changing the UJs; you make it sound easy!

SS4; yes, I would get it balanced.

 

[Robintr6]

Don't worry ujs are easy. Get shaft on bench tap in the uj cup on one side inwards and thus drive out the opposite side cup. Reverse order to remove opposite cup. Obviously remove circlips before starting. Remove caps insert new uj..tap in one tap then opposite one then use a vice and suitable socket to push in one cap so you can replace circlip. Then same again for opposite cap. Then do the other pair. Care to be taken to protect roller bearings in caps when removing and replacing. They Re in grease so should stay in place.

 

[Sma]

Hi guys

I'm new here and also have the same problem (propshaft vibration). I just had the propshaft balance after i had put in a new center bearing, new front, center and rear couplings. I noticed that the gearbox mounting is lose but i can't seem to located nor see it (first problem i need assistance on). Second thing is that i dont know what are this UJ's you have been mentioning. Is there another name for them and where are they located?

Thank you

 

[cockney21]

Just a note on earlier post re. engine mounts. My son's Ti mounts looked fine if a little old, but once out found one with metal backing snapped and the rubber on the other just pulled off with no effort. Only real way to check is to gently jack the engine or take off and inspect.

 

[Joe90GT]

Hi guys

I'm new here and also have the same problem (propshaft vibration). I just had the propshaft balance after i had put in a new center bearing, new front, center and rear couplings. I noticed that the gearbox mounting is lose but i can't seem to located nor see it (first problem i need assistance on). Second thing is that i dont know what are this UJ's you have been mentioning. Is there another name for them and where are they located?

Thank you

UJ = Universal joints - one just after the centre bearing and one connecting the diff - what you refer to as couplings - the front one is called a Guibo rather than a UJ as it does a slightly different job - oh and welcome to the forum by the way - some pics and detail would be good