Morris Minor Owners Club

Hi people,

I am new to the forum and have found lots of useful info so keep up the good work.

I have fitted a fiat 2ltr twincam into my newly rebuilt 71 traveller. The engine, gearbox, rear axle and propshaft are all from the same car. I had the 2 piece prop shortened, a new centre bearig and UJ, the prop was then balanced. This work was done by a professional. I fitted a new rubber donut to the spigot on the gearbox.
The front short section of the pop is aligned and in level line with the gearbox and from the centre bearing bracket the prop drops down at a slight angle to mate up with the flange on the rear axle. I have fitted anti tramp bars and a panhard rod and a anti roll bar to the front with ajustable dampers all round.

My question is that despite having all the above work done to the prop, I am still experincing vibration and a drone when the car is driven hard through the gears ie. under accelleration but doesn't happen under normal driving.

An ideas what the problem might be would be really appreciated. I
Cheers

Keith

We were informed that the Fiat UJ's, infact any prop UJ will suffer if expected to cope with more than 26 degrees. We used to fit the 2 piece item as you have but the short end which fits into the box is too short and has too great an angle. Dave Mac Propshafts built us a 2 piece prop which replaces the 3 pronged Fiat design with a flange. to this bolts a similar flange and UJ and a suitable flange and UJ for your axle.
Have you measured accurately that the axle is central in the car (do you have an adjustable panhard rod and how is it mounted.
Are the tramp bars the ones that bolt to the U bolts and front spring hanger. If they are the original Fiat ones did you weld them to the floor on suitable load plates and whilst the car was at laden weight
Check that the gearbox mounting and X member are strong enough and are not allowing the box to twist under acceleration. Was the rubber doughnut new.

Hi Jonathon,
The axle is as centralised as I can get it. The prop flange is slightly offset on the diff so I have measured and centralised the axle between the chassis rails by taken as many measuremants as possible. Measurements like from the drum back plates etc all tally up to the rails. The prop is in direct line between the diff flange and the gearbox spigot.
I have a short panhard rod fitted to the side chasis rail and bolted via a plate to the top of the diff. It is not adjustable.
The tramp bars are the off the shelf mods that fit to the "U" bolts and front spring hanger.
The donut is new.
The geabox X member I made myself which I think is strong enough but now that you mention it I could make a bigger stronger one.

What do you think about the panhard rod fitted?

Cheers

Keith

Short Panhard rods are a very bad idea! They should be as long as possible - to minimise sideways axle shift on suspension compression. Try the car with the Panhard removed. A Watts linkage would be very much better.

A panhard rod fitted to the top of the diff is a very bad idea. The location of the chassis mount and the axle mount should be horizontal/level at normal ride height, with the whole assembly no higher than axle centre height. To get the panhard rod at the correct height a suitable tower will need to be fabricated with suitable stiffness. The panhard rod pivot heights effect the roll centre height and having then at the top of the axle case is bad. Short panhard rods are not good if the suspension travel is long, however a short one can be used successfully if the suspension travel is short (circuit race set up) and if the pivots are at the bottom of the axle case giving a useful lowering of the roll centre.

As BMC says, better to go for a Watts linkage (provided the pivots are in the correct place) or even a Mumford link if you are feeling adventurous.

Martin

Hi MatinB and bmcecosse thanks for your input.

What you say makes great sense now, when I was doing it, to be honest something was niggling in my head about the length of the rod I was fitting but it was easy and a convenient way to fit one. What is a Watts linkage and where would I get one. Do either of you have any photo's of this type of set up.

I have the original fiat panhard rod which I could use in the set up that you suggest. Again with the tower support suggested do you have any photo's of the type of fabrication used to enable me to achieve the correct bracket/tower support and strength.

With regards to my other query about vibration do you think that the pan hard rod that I am using would contribute to the problem???? and do you think that I would be better having a one piece prop made up to eliminate the centre bearing and hopefully the vibration.

The gearbox crossmember that I have made up is a "T" section from 4mm thickness about 45mm wide with the centre section about 40mm deep so overall 45mm. I have used 2 bolts each end fixed with captive nuts into the chassis rails. Do you think that this is strong enough but if not again have you got any photo's showing a made up crossmember which has been successful for fiat into minor.

As they say "a picture says a thousand words"

Regards

Keith

Here's some of our 4 link plus Watts linkage<br><br><br><br><br><br>

The brackets for the Watts link are welded to the Coil over turrets and an internal 60mmx40mm 3 mm box, not the boot floor (this was cut away to ensure a good weld to the box section)


I'll try and post the panhard rod later.
Mods please feel free to reduce the file sizes of the images.

Cheers Jonathon,

Watts linkeage is clear now.

Whilst looking for the panhard photo can you aso see if you hve a photo of a typical gearbox X member.

Keith

Here is our Fiat TC gearbox X member

<br><br>


And another of the Watts link


Cannot find the panhard rod atm but can take one soon when the cars on the ramp

<br><br>

Jonathon I have PM'd you.

Keith

If you're not experiencing vibration/droning under normal driving conditions I would suggest there is not much wrong with the basic job done [ other than the bad location of the Panhard rod ]
As you say it is only happening under hard acceleration through the gears , you need to consider what is altering to give you these symptoms .
The rear is squatting down : - is something binding , or touching the chassis/body . The distance from diff flange to g.box will reduce , is there enough movement allowed in your prop etc ...
A good first step is to remove both rear spring hangers so the rear of the springs sit on the rear chassis legs , lowering the car .
Now have someone vigorously bounce up and down in the back of the car and have a look underneath to see how the suspension and prop etc are working . - nothing like a bit of real time testing

If you're only using the car on the road a well located Panhard rod will be your best option , anything else will be lots more work for no gain - unless like Martin you're going to put some puff into your Fiat lump

Thanks carlt,
Based on all the input in his tread I will definately be fitting a better panhard rod, one as long as possible and level with the axle. Something else has come to light and that is the gearbox X member. I have re-used the original fiat rubber mounts/fixing on the gearbox and bolted that to my made up X member. I now think that this s a weak spot and allowing the gearbox to twist under heavy torque. This too will be addressed.

Regards

Keith