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Crank Damper Advice


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#1 Minigman

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Posted 16 June 2018 - 03:26 PM

I’ve just had an uprated 1098 engine rebuilt.

Whilst at the rolling road I was told it should have a damper fitted.

Now having looked about the damper needs balancing with the crankshaft presumably before the engine has been reinstalled and done 700 miles.

Shall I just get a standard one for a 1098 and put it on or is too late? The S ones probably aren’t the correct ones?

#2 absx2

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Posted 16 June 2018 - 05:22 PM

If it was mine I would just put the standard 1098 damper pulley on. They are quite chunky on the 1098, I think the 998 Coopers used the same one and as for balancing its so small in diameter I think you would be splitting hairs to make any worthwhile difference.

Do fit a 1098 damper as a matter of urgency as it does need one to reduce the chances of the crank breaking. 



#3 nicklouse

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Posted 16 June 2018 - 05:55 PM

standard ones used to come balanced. it was only the S type that needed balancing.



#4 Spider

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Posted 16 June 2018 - 07:48 PM

Yes, all 1098 engines, in my books, must run a damper. As the other guys have suggested, just a 'stock' damper will be fine, no need to go to an S type Damper, however, be aware of some of the new ones on offer, the coff coff rubber coff in them isn't rubber (I think it's Polyurethane), apart from having the wrong characteristics, they fall apart in short time. I'd actually suggest finding a good used one or having an old one refurbished.

 

If you've already had the rest of the bottom end balanced, just have the damper balanced on it's own.



#5 Minigman

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Posted 16 June 2018 - 08:13 PM

Thanks Moke Spider. I can’t work out why it didn’t get fitted by the engine builder. He is a well known and respected engine builder and I paid him for a turnkey job.

So far the set up was awful. He failed to get to grips with positive earth wiring. And now the crank damper has been missed off. The std 1098 damper came back with the engine unfitted. He’d just used the one of my 850 engine that I drove in with.

Not too impresss with him at this point.

I’m assuming the rad etc has to come out to fit it?

Thanks for info so far.

Edited by Minigman, 16 June 2018 - 08:21 PM.


#6 Minigman

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Posted 17 June 2018 - 08:41 AM

I’ve been told that the early 1098s didn’t have a crank damper. Maybe that’s why it was left off.

#7 Spider

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Posted 17 June 2018 - 09:17 AM

I’ve been told that the early 1098s didn’t have a crank damper. Maybe that’s why it was left off.

 

They were all fitted with a Damper.

 

The 850 and early 998's didn't have one, but a 1098 needs one.



#8 Homersimpson

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Posted 17 June 2018 - 07:40 PM

I'm interested in this as I had a Frogeye a few years back that was fitted with a 1098 Morris minor engine (CG) and then I fitted a later midget 1098 (CC) which had the better crank and neither had a crank damper pulley.  I still have the CG engine and another CC engine which I may rebuild in future if I ever do another Frogeye.

 

I've just looked on e-bay and the Morris Minor engines on there all seem to have solid pullys but the Mini ones have dampers.  What happens to the crank without one?



#9 Minigman

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Posted 17 June 2018 - 08:25 PM

The early ADO16 1100s didn’t have a damper either.

#10 Spider

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Posted 18 June 2018 - 06:08 AM

I've just looked on e-bay and the Morris Minor engines on there all seem to have solid pullys but the Mini ones have dampers.  What happens to the crank without one?

 

The Morris Minor from memory has a 3.2" stroke but also it didn't make a lot of power. I'm surprised to read that the 1098 Sprite Engines weren't fitted with them.

 

The function of the damper is to dampen crankshaft harmonics, especially at critical RPMs where it gets in to a resonance, these harmonics are destructive especially at the resonate RPMs. From memory, the critical RPMs of these engines is around 1300 - 1400 RPM and any multipals thereof, becoming more of a problem at 3 times these RPMs.

 

Usually, the longer the stroke and more spindly the crankshaft - like the 1098 ones - the greater the need for one becomes.

 

Do a seach on the forum for Crankshaft Harmonics as it's been discussed in some detail previously.



#11 Minigman

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Posted 18 June 2018 - 09:16 AM

Do you need a longer crankshaft bolt to fit one?

#12 Cooperman

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Posted 18 June 2018 - 09:34 AM

You shouldn't need a longer bolt.

A standard 998 Cooper crank damper will be fine and don't worry about the balance as it won't be a serious issue unless you intend using over 6000 rpm. The damper will just improve the smoothness at those 'certain revs' as 'Moke...' has mentioned.

A 1098 engine gives good torque rather than top end power, so high revs is not really an issue.



#13 Minigman

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Posted 18 June 2018 - 09:48 AM

I have the 1098 one but the engine builder decided not to fit it for some reason.

I’ve asked him the question but yet to get a response.

Is this a rad out job?

#14 RooBoonix

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Posted 18 June 2018 - 04:42 PM

I think it'll be a rad and engine mount bracket out job, as at least with my 1275 they're pretty close and there isn't enough room directly outwards to pull the pulley off of the crank. I may be wrong, I am going from memory.

Sorry if I'm wrong, and I'm also sorry if I'm right! (Nothing is ever easy is it!)


Cam.




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