Do Rimmers know what they are doing?

[JohnD]

You may know of my interest in torsion vibration and Triumph's use of crank dampers to suppress it in their long-crank six cylinder engines.    I've learnt that Rimmers sell a damper as suitable for both 2L and 2.5L engines!  See: Pulley & Damper Assembly - 3/8 inch Groove - 214479 (rimmerbros.com)

The original dampers for these two engines were significantly different.    The 2.5 crank is much heavier as a result of the longer stroke, and Triumph redesigned the damper to cope with it.   The inertia ring clearly needed to be much heavier, so that they incorporated the groove part of the pulley, and fenestrated the hub to make that lighter.

   2 Litre damper pulley

 

   2.5 Litre damper pulley

 

Dimensions: Diameter        Mass        
         2L        150mm    1600gms
      2.5L        165mm    2600gms  

Although no weight is quoted, the Rimmers product is clearly the 2.5L type with groove and ring in one piece, but has no fenestrations.     

 

I will ask Rimmers if their product has been  tested on a 2L crank, and will offer to do so if not.     Meanwhile, I suggest that 2L owners should be cautious if they need a new damper!

John
 

Edited February 14, 2023 by JohnD

[yorkshire_spam]

"Do Rimmers know what they are doing?" 

Erm, yes and no. I have a history of parts that are not fit for purpose from them with the same cut-n-paste answer of "we'll take it up with the supplier" followed by no meaningful response. Alongside that I've had special tools supplied to me that were in fact just cheap generic tools that were "almost what I ordered" 

So in terms of that sort of thing, I suspect they know exactly what they are doing - making a profit.

I won't order from them anymore unless they are the ONLY place I can get something. 

[Nick Jones]

23 minutes ago, yorkshire_spam said:

Do Rimmers know what they are doing?" 

I wouldn’t assume so.

In this case the fall at the first hurdle is that when you try to fit a 2500 damper on a 2L, it’ll foul on the timing pointer.

2L one’s seem less failure prone. Probably because the rubber is not involved in driving the belts.

[Escadrille Ecosse]

On 2/14/2023 at 12:48 PM, yorkshire_spam said:

I won't order from them anymore unless they are the ONLY place I can get something. 

Tend towards a simmilar approach although it can be hard.

Having said that when I built my 2.5 I basically took the 2L bottom end and swapped out the crank and pistons. Kept the pulley from the 2L. Had to use the 2.5 flywheel because the crank had the 'long' boss but I got that lightend right down until it weighed less than the std. 2L. Seemed happy enough

[Nick Jones]

4 hours ago, Escadrille Ecosse said:

Kept the pulley from the 2L

 What did you rev too?  Must have been from a pretty early engine if long-tailed, was it cross-drilled too?

[Escadrille Ecosse]

3 hours ago, Nick Jones said:

 What did you rev too?

Road use it was bloody torquey and with the close ratio gearset and J Type TR box there was little need to go much above 5k. For sprints and hillclimbs tried to limit it to 6k as it would be heading off the other side of the TR5 cam but it would run to about 6.5k or so in the heat of the moment before telling you it had had enough by simply refusing to go any faster. Unlike the 2L which just seemed to keep going indefinitely - which was a bit scarey.

Everything inside was well balanced though and not sure I would want to do circuit racing with it.

3 hours ago, Nick Jones said:

Must have been from a pretty early engine if long-tailed, was it cross-drilled too?

I managed to obtain a new old stock crank in the wrapper. I had hoped, but it wasn't cross drilled unfortunately. Engine always had excellent oil pressure.

 

Edited February 17, 2023 by Escadrille Ecosse

[JohnD]

21 hours ago, Nick Jones said:

 What did you rev too?  Must have been from a pretty early engine if long-tailed, was it cross-drilled too?

I found a cross-drilled 2.5 engine for sale locally, and got rather excited, as I didn't know that early ones were built so in the factory.   Ho, hum, got it home and discovered that the thrust bearing surfaces in the block were worn away.    It's really scrap, but I've still got it!

[michaeljf]

Hello John, How worn. You can have them machined and fit a set of Toyota ones as I have mentioned in my thread. Regards, Michael.

[JohnD]

Please save me a search, Mike?  Post a link?  John