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Balancing the Radiator Fan - Re-tightening the Starter Dog


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A loose fan and distorted pulley have necessitated a replacement/rebuild of this area, on my '55' TR2.

 

Also, when I came to it, I could virtually undo the starter dog without any tools!

 

The 'Haines' refers to the essential need to balance the radiator fan - indicating specialist equipment or expert intervention. I note that the Moss catalogue includes a balance weight for this (original) fan. How vital is this in the process? How essential expert equipment to place it appropriately?

 

I will need to replace the fan bushes, sleeves and the associated bolts and have a new starter dog bolt and replacement (old) pulley - will get that timing chain cover off as well and replace the oil seal whilst at it.

 

Finally, is putting the car in gear sufficient resistance against which to tighten the starter dog, or is better technique required?

 

Although, as a private owner, I have run 'classic' cars all my life (now retired), I've only recently acquired this vehicle and have not previously experienced a radiator cooling fan quite like it!

 

Contributions gratefully received

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Welcome DougK - Where are you in the world?

 

Cooling fans.....

Are you a purist?

 

If not remove the mechanical fan and fit an electric replacement. Simple 4 bolts that hold the fan and bushes to the extension. No need to balance then either.

The electric fan can be a proprietary kit with thermostatic control or something you build yourself with bits from a breaker's yard and control with a dash mounted switch when needed. It fits neatly behind the radiator out of sight.

Lots of useful help on this forum as to how it could be done.

 

If you are concerned about the big bolt coming loose fit the lock plate. 108497 - In truth I have never needed one in 40 years of ownership (nor a mechanical fan come to that)

https://www.moss-europe.co.uk/lock-tab-crank-bolt-108497.html

 

Cheers

 

 

 

Peter W

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"If you are concerned about the big bolt coming loose fit the lock plate. 108497 - In truth I have never needed one in 40 years of ownership (nor a mechanical fan come to that)"

 

https://www.moss-eur...olt-108497.html

 

Cheers

 

Peter W

 

 

That's good info Peter, I didn't know that part existed.

In the absence of ANY torque being specified on the TRs for this "dog bolt" I fit mine at 120 lb ft which is the torque specified for the Stag crankshaft bolt and by my reckoning if a Stag needs it so does my TRs. I use a large Stilson (monkey wrench type) spanner on the extension nose and braced against any convenient "chassis or body part that is secure enough to stop it turning. A BBrrrpppp with the impact gun and off it comes, reverse operation for tightening back up but use a torque wrench to make sure it gets enough torque on it accurately.

Failure to tighten the pulley will allow it to chatter it's Woodruff key against the pulley keyway and will "machine" material away from the keyway likely ruining it.

 

Mick Richards

Edited by Motorsport Mickey
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To undo or tighten crankshaft bolt / starter dog using an old fanbelt

 

I used this method last year on the TR2. It works well, no need for impact wrench or trying to hold the crank steady by putting it in gear. I used an old fanbelt from the TR but depending on the diameter of your pulleys, you may need a different fanbelt. No issues in torquing the bolt back up either

 

Phil

 

 

Undo crankshaft pulley bolt.pdf

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Phil,

 

Sounds good, did it really hold the crank nose still whilst you put 120 lb ft on it ?

 

Mick Richards

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Surely that's not very nice for the alternator bearing nor the body and mounting bracket ? What about the alignment of the pulleys afterwards?

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Balancing is a thing that never does any harm.

 

Question is from what point it is necessary to do so.

I would recommend to do that on engines that run frequently

over 3000 rpm, what means the TR3 should benefit from that.

 

I big role plays with no doubt the weight of the imbalance. As we do not

know that before balancing I would balance all suspect parts.

 

After reading the book from Ludwig Apfelbeck

I decided to make my own equipment, maybe not perfect

but often pointed me in the right direction.

 

This is a TR6 pulley, modified to accept a trigger wheel for

injection and ignition. A shaft has to be made for the correct

center of the part to balanced and to rest with a smaller

diametre on the rotating discs.

 

post-13092-0-77877600-1522911017_thumb.jpg

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Phil,

 

Sounds good, did it really hold the crank nose still whilst you put 120 lb ft on it ?

 

Mick Richards

 

Yep

 

Phil

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Thanks everyone. I’ve filled in some of my details now.

 

While not a purist, I was looking for some ‘quick wins’ without any major work, to run the car about a bit - possibly laying it up for more work over next winter (a rewire to start with). With only 2.5k miles done over the last 25 years (just two owners over the past 50) and an MOT until five years ago, it appeared not far from being a viable runabout for a while.

 

Once the front apron has been taken off, of course, (to sort the radiator fan) there’s so much else you can get at and could do with a clean or ‘quick fix’ while about it – and on it goes.

 

I’ve had an offer of an unused ‘yellow fan’ conversion kit (TR6 type) and am coming round to the same conclusion that I always seem to: that the car must be viable in modern traffic conditions. I also appreciate that, all other things being equal (clean water-ways in engine and radiator) there’s no reason why the original equipment and design shouldn’t see one through.

 

I’m avoiding an electric fan for the moment, but have fitted them on ‘classics’ in the past, with just a manual switch to flick on in an emergency – like crawling along the M25 for a couple of hours in 32 degrees C.

 

Welcomed and valid replies everyone, thanks, together also with the kind of ingenuity I’d expect (and wish I’d thought of).

 

It now appears to me that, whatever ‘fan’ job was done in the past, even with the ‘lock plate’ fitted (that Peter W kindly mentions) the starter dog bolt may not have been sufficiently tight in the first place and all hell had broken loose down there – damaging the fan bushes/sleeves/bolts and allowing the woodruff key to chip away also at the groove in the pulley bush. Also, no balance weight on the fan - which I'm gong to circumvent anyway, now.

 

Thanks again. As always, plenty to think about.

Edited by DougK
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The balancing procedure is in this workshop manual- pages 9 and 10 in the Cooling section (97 and 98 overall).

 

http://tinyurl.com/83x4e45

Thanks, Rob. Missing are details of the " balance piece " and the jig used to determine the light side of the assembly. If an original example is to hand, it seems the best thing to do is heed the marks for the balance piece ( drilled to mark same ) when reassembling, and I assume fitment of new rubber bushes won't affect it.

 

My guess is 50% + of the cars today with factory fan blades are imbalanced. If I had a 4-pot TR I'd try to make the metal fan work, after determining that available ones are of original / + quality.

 

Cheers,

Tom

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Were I going to go through the headache, Tom, I'd probably try one of these, the first one in particular:

https://www.harborfreight.com/motorcycle-wheel-balancing-stand-98488.html

https://www.harborfreight.com/portable-wheel-balancer-39741.html

 

But to be honest, I'm not sure either one would make much difference.

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Take it down the tyre shop and ask if it would fit their dynamic balancer perhaps. You would need to stand over the operator with the balance weight, to get them fitted and locked in place.

 

 

Don I like the look of the cheaper balancing device from Harbour Freight - The bubble type we have a version of that we bought from Burt's Motors in Wimbledon many years ago.

Peter W

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Hi Marco,

 

The instructions are to balance the extension piece and pulley with the fan as an assembly, fitted with new parts ( rubber bushes at least ) as necessary.

 

Thanks for the suggestions, Don. I think those are for much heavier objects, but I get the principle at least.

 

I would take it to a gear shop we use who balanced a MOSS damper for me ( drilling holes ). I suppose if the " balance piece " were not available they would use an assortment of washers ( which can be ground for intermediate values ) to find and place the proper amount of weight.

 

Ciao,

Tom ( not Italian but my wife is and I speak it )

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Tom, I wouldn't sell short the idea of a good set of bearings to find a heavy point. On a road bicycle wheel on my truing stand and the standard axle, it takes less than a minute to find the heavy point on the rim, usually the valve stem on a lightweight alloy wheel and tire.. If you could chuck the fan carefully, I'm quite sure that motorcycle wheel balancer would get it done.

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Hi Marco,

 

A shop that does balancing should be easy to find in Germany. Here in the 'States every city of any size will have at least one.

 

As I mentioned above, washers can be used to effect the balance. Yes, it would be interesting to see what was originally used.

 

Tom

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Here's what the balance piece on my TR3B's fan looked like originally, before the engine was torn down around 2009-2010. You can see the tiny hole drilled in it per the service instructions. (Click on the image for full size.)

i-55MdWNT.jpg

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