Engine Damping forces - technical question.

[MattNoVAT]

I have found an alternative set of engine dampers that will fit the Beta twin cam engine with only very minor modification. (Drilling out the bolt hole from M8 to M10)

The technical question I have though is this:

The dampers are different lengths (despite what the Haynes book of lies says) and for the alternative engine damper at the timing belt side has three options for damping force.

1. 100 Nm
2. 400 Nm
3. 1000 Nm

My concern is that if I buy option 1 it may be too soft and if I, if I go for option 3 then it way be too stiff and transfer the forces through the chassis (this is what happens when the original dampers sieze up).

Does anyone have a better techincal grasp of damping forces and can pass comment?  Am looking for something more scientific that just "Go for the middle one!"

Cheers
  

[Hawk]

the Haynes book of lies    

lol - I have the same view

sorry, can't help with technical input but I'd be interested to know the outcome

[WestonE]

Matt

Can you get a sound one into a school physics lab and have it measured? I am definitely interested and would tend to the stiffest for my application as I was already considering a pair of mid range polybush do nuts with an adjustable coupling as a solution.

Thanks

Eric

[MattNoVAT]

Eric et al,

I think I may have worked it out ... sort of.  (I'm definitely no physics student!)

I got the technical spec of the gearbox side damper to see what that is designed to cope with.

This is what I got back from the manufacturer:

Damping area 1200 Newton
Stroke 39 mm
Outside diameter 18 mm
Outside diameter 224 mm


The Damping area of 1200 Newton on the shorter gearbox end makes me think that a longer version for the cam side with a Damping area of 1000 Newton will be the best option.  

Reason: With a longer unit I think the Newtons that it could cope with would be reduced because of the increased overall length?

Would you concur?  Or am I just convincing myself?

[rossocorsa]

I don't think the length of the damper has much relevance it is the damping effect that matters I'm afraid that I have no idea what 1000nm means in the real world but these dampers do appear fairly stiff when working, will be interested in the outcome as I need a solution myself, did see a new one on ebay but it was expensive and I dithered ....someone else snapped it up whilst I was dithering    (lesson learnt with Beta parts worry about your bank balance later...)

[WestonE]

Matt

I am not at all clear what "damping area" means however I would have thought the other dimensions are range of travel with damping in action assuming this is linear. We know that even Betas with the most soggy engine mounts do not use the full travel on the OE units but they are vital to stopping the engine jumping about in the engine bay. Without getting more information that we can understand/ compare I think you have to buy and try starting with the 1,000 nm items.

Eric
PS getting them onto a running used car ASAP is the best way I can think of and I would have thought hold the engine steady was far better than the whip motion that kills exhausts and ruins gearchanges. 

[MattNoVAT]

I will be buying (hopefully) the 1000Nm version today and fitting to my red coupe asap - so I will be able to report on the results of fitting both alternative cersions of the engine dampers.

While I see the validity of changing one at a time to see which provides the most noticable improvement, I figure changing both at the same time will save me time and provide the desired immediate all round improvement.

[MattNoVAT]

I have ordered the longer 1000 Nm unit and it's a 4 week lead time :-(

Also, its amazing how costs spiral on these things, the part itself was £67.40, then the dreaded VAT and add shipping and its a £90 bit of kit.

I have only ordered one as I want to make sure its the right part first.   (The sales consultant I spoke with yesterday never phoned me back and the woman I spoke to today from the same company seemed utterly dis-interested in anything other than reading what the computer screen said)  So I reverted to ordering it via their own website.

[thecolonel]

Worth a call to Guy Croft or post on his forum
1000nm seems rather high to me.

[HFStuart]

Just thinking about this I suspect that the damping area is a nominal level of force about which it can provide damping effort.

I'd suspect that much below this level the damper remains rigid and above it it doesn't damp at all. If that's the case then the cruicial thing would be the distance for the mounting from the axis of twist of the engine. The further away it is the lower the forces will be. The length of the damper shouldn't have any effect.

This is all specualtion on my part but it seems logical!

Stuart

[MattNoVAT]

1000nm seems rather high to me.

The gearbox damper that I have the spec for operates pretty much identical to the OEM item used by Lancia, at that can cope with up to 1200 nm.

In fact the modern equivilent looks to be a slightly updated version of the OEM item anyway, they are so close in fact that I would probably wager a small sum that they were both made by the same manufacturer just 35+ years apart and with a small amount of evolution in the manufacturing process.

[WestonE]

Matt

No body else has said yet so I will, Well Done for finding this as Beta owners really need this part!

Eric 

[Hawk]

Matt

No body else has said yet so I will, Well Done for finding this as Beta owners really need this part!

Eric 

Good point!  Yay Matt!

[targa2000]

Matt
Fitted the gearbox damper today,apart from drilling out the mounting holes to 10mm and installing a couple spacing washers it went in a treat, looks really original as well.
Spoke with my contact today and gave him the spec of the crank pulley end damper,awaiting his reply with interest.

[Neil-yaj396]

Could we save some money with a bulk order, or could Betaboyz look into getting a stock?

[MattNoVAT]

Yes, could do I guess but first things first.  I need to test fit and try the car out with the alternative dampers fitted to ensure they do the job.

I think they will be spot on but I need to be certain.

[MattNoVAT]

Update on the compatibility of the longer damper (Cam belt side).

Today I received the alternative engine damper for the cam belt side on the Beta twin cam engine.

Visibly it looks absolutely spot on, the size looks more or less identical to the original other than the eye holes for the bolt through the centre of the bush is M8 rather than the original M10, not the end of the world and easily modified.  The physical force required to compress the damper seems to be pretty much identical to the gearbox side damper.

Fitting to my red coupe will be done on 4th April, so I will be able to provide results of its performance soon after that.... maybe ask me at Goodwood !

 

[MattNoVAT]

Have fitted the new damper to the cam belt side this morning (later than originally planned) the new damper took 20 minutes to fit and that included washing my alloy wheel while it was off.  It fits perfectly and the only modification is to drill the bush out from M8 to M10 to take the original Lancia bolts.  Gearbox damper was replaced when I changed the gearbox at the start of the month.

Will test the car later today but so far its all looking very positive indeed.

[Neil-yaj396]

These must be shot on most cars now. Why don't we get a list together and put in an order. We should get a discount then? Alternatively is Mark W interested in sourcing them via Betaboyz parts?
 

[MattNoVAT]

Why don't we get a list together and put in an order. We should get a discount then?

When I spoke to the distributer he advised that there is discount available if we buy 10+ = about £60+ VAT a piece instead of £65+ VAT but I could ask if he can improve on that.  With current work commitments, restoration finance commitments and finding steering dampers and general forum admin stuff I'm kinda pushed at the moment and cannot shell out £700+ up front.  First thing we need to do is sort out numbers required.  Then we need to gather up the funds into one lump then do a group buy.  While I don't mind going back to the supplier and organising the deal I can't commit right now to getting the group buy organised.

Unless folks can wait till things calm down a bit a my end..