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Gearbox vibration damper


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Good morning from France,

 

On a set of original old used spare parts, I discovered a gearbox vibration damper, as per the service note n° 2/53 dated May 1966 (for reference see the attached 2 pages, thanks' to Bad frog (RIP)via the British car US Forum), this parts was incorporated on TR4 models at approximately comm. N° CT18000 to reduce vibration between engine speeds of 2700 and 300 r.p.m.. Another source (not documented)say, installed on the TR4 from CT17815 to CT35719.

post-12941-0-70670600-1439194545_thumb.pngpost-12941-0-71187000-1439194549_thumb.png

This part was introduced for the TR4 (Cong 4 cyl. + GB w/ or w/o OD) is it a part suitable & useful for the 6 cyl and is it something I can keep and installed to the TR6 ?

 

Thanks's for sharing your knowledge and your advises

 

Regards

Edited by Marc R
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Hi Marc,

it was fitted also to the TR4A and is peculiar to the 4 cylinder engine. Not required on a 6 pot.

 

The 6 pot engine is naturally balanced.

4 pot engines, in general, are not very well balanced due to their firing order.

 

Roger

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In my opinion this damper is related to the propshaft, not to the engine.

It is mounted at the back end of the drive unit where

the propshaft vibrations attack that unit.

 

The engines vibrations attack the frame by the engine mounts

that devide the engine weight nearly half by half and from that

the engine will not do that much harm in vibrations at the rear of gearbox.

 

I have two of these nasty vibrators between the seats

and the more you do with balancing the engine and the wheels

the more it drives you mad when there is still that vibration even when small

comeing up beyond 130 Km/h and leaving at 180 Km/h.

 

If question might come up what this has to do with TR4:

The vibrations are related to revs of propshaft and as the TR4

has another ratio (4,1:1) this will happen much earlier.

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Thanks' Roger and Andreas for you feedback, interesting debate if this is to cure a vibration from the engine or the transmission!

I shall keep this damper and test the effect on the TR6 (when she will be back on the road...)

 

Regards

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Hi Marc,

 

the 'damper' is a pretty crude device, but it does have at least some beneficial effect on the 4-cylinder engine's vibration period . . . . . which, incidentally, seems to me to be more pronounced on the 2138cc than on the smaller and earlier 1998cc engine.

 

As already noted, it is simply not required with the 6-cylinder engine, there is no equivalent vibration period to be damped . . . . . dead metal !

 

Cheers

 

Alec

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How likely is it that the original Slilent-Bloc rubber bush isolating the steel mass has the properties originally intended by S-T? Seems unlikely to me, and the damping properties would likely be affected as well. The equivalent of fifty-plus year old suspension bushings.

 

Good curiosity piece, but it would take some convincing to accept that it would still work as designed...

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Hi Don,

I can see your point. But I think the basis of it working is predominately the mass.

 

So why is the rubber bush there !! Hmm, Where ST that clever?

 

I removed my lump many moons ago and have felt no excess vibration. I think it must have vibrated so much it shook itself free and fell off the end.

 

Roger

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The one I have, is in very good condition for an old part, certainly out of a TR4 since years. The rubber bush part, as I can see in bothe side look w/o crack..

 

Regards

Edited by Marc R
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In my opinion this damper is related to the propshaft, not to the engine.

It is mounted at the back end of the drive unit where

the propshaft vibrations attack that unit.

 

The engines vibrations attack the frame by the engine mounts

that devide the engine weight nearly half by half and from that

the engine will not do that much harm in vibrations at the rear of gearbox.

 

I have two of these nasty vibrators between the seats

and the more you do with balancing the engine and the wheels

the more it drives you mad when there is still that vibration even when small

comeing up beyond 130 Km/h and leaving at 180 Km/h.

 

If question might come up what this has to do with TR4:

The vibrations are related to revs of propshaft and as the TR4

has another ratio (4,1:1) this will happen much earlier.

Nothing to do with the prop but all to do with the engine and as Alec noted more on the larger capacity. Also 4:1 axles are rare most have 3:7.

Stuart.

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