Fiat Dino Forum (FDF)

I forgot to mention that I has a vibration at around 70 km/h, as in the case described by Thomas.

Trond

Hi Trond,

Yes, exactly - Fiat part number 4211466. If you're going to change it then let me know - I have tips on how to do it.

70km/h - yes, same for me - especially when coasting (no throttle, so wheels are turning the driveshaft effectively)

-Richard

Thanks Richard!

I will investigate it a little bit further first. But will appreciate advices when I change this part!

Trond

Hi Richard.

What type of rubber engine mount do you use? The original square or an alternative round? It's important that you use the sqaure type. Correct height and rigidity of the engine rubber mount is only guaranteed with the original type.

A difference in height of the mount compared to the originall causes an inclination / wrong angle from crankshaft / gearbox to propshaft. The donut / hardy disc will be bent. This is obviously not the only reason for vibrations but it adds up with existing wear and tear of the propshaft.

Also check if not already done if the rubber transmission mount is in good order and correct type.

I doubt that the rubber ring at the torque tube wears. It is a very solid part. But I would not exclude that a replacement can have an additional positive effect.

The only source for the square type engine mount I know of is Maurizio Zanella who lives somewhere at the Venice (Italy) area. Cellphone # +39 338 6274142.

Georg

Original type and alternatively offered spare.

Hi Georg,

Thanks for your info regarding the engine mounting rubbers.

What is the height of the correct square rubbers? ( I think that's most important)
My current (old) rubbers are 42mm and the replacements I got are 50mm so I am unsure what to fit.


Kind Regards
Tom
PS is it doable to fit new ones without removing the exhaust or mountings to the engine block?

At drivers side I have managed to change it from downside, when the engine hang on a crane. Other side is more difficult due to the starter...

as Thomas says above, I think the starter motor side would be very hard to do without the exhaust downpipes removed.

Maybe use this as an excuse for stainless downpipes and re-furbish the starter-motor while also fixing the motor mounts?

-Richard

Thanks for thinking along!

I guess I will just have to try it!


But what about the mounting rubbers Thickness? I want to make sure to fit the CORRECT height rubbers, especially because it's quite a job to replace them.... What height of rubbers do you have fitted? (and is your car virbration-free?)





Kind regards
Tom

Hi folks,

the engine rubber mounts are now available at Holtmann & Niedergerke.

http://www.ebay.de/itm/Motorgummilager- ... 43d36c60b7

Partnumber is also correct.
http://www.dinoparts.eu/uploads/PDF/FIA ... _A0.01.pdf

I'm not trying to do any kind of advertising, but as I also have some
problems with drivetrain vibrations I just wanted to let you
know...

Has anybody ever balanced the small two prop shafts (with 2 u joints) that go from the diff to the wheels?
I brought mine to a workshop specialised in driveshafts and they told me they are not able to do balancing works for that type of prop shafts. I know that they are rather short and balancing may not be required but
I definitely want to rule them out as being the culprites.

Cheers

Bijan

Hi Bijan,

Like you, I doubt that those shafts could cause vibration by being out of balance - too short. But, the Universal Joints have to be in good condition with their yokes in-phase (although I don't think you can get that wrong). Mine had loose nuts at the differential end for some reason - that really didn't help.

I think you could eliminate this by thinking about the frequency of vibration - if it's in the rear half-shaft (as I call them) then the frequency will be lower than in the central propshaft due to the diff's ratio. 9:43.

I'll do the calculation in case it's useful Let's say the vibration is at 100km/h. That's 1000 x 100/3600 metres/second = 27.8m/s
205/70-14 tires have a circumference of (((14 x 25.4) + (2 x 205 x 0.7)) x pi)/1000metres = 2.02 metres
So at 100kph, your rear wheels, and therefore your half-shafts are rotating at 27.8/2.02 = 13.75 times per second, therefore a fundamental frequency of about 14Hz.
But your propshaft is going at 43/9 times that or 66Hz.

14Hz is pretty rumbly and low, not really a "tone" as such - whereas 66Hz you could definitely feel and hear, like a hum. Of course there are secondary harmonic effects that could affect this method, but it gives an indication.

And someone please check my sums!

Thanks,

-Richard