Water pump/alternator belt tensioner

[ianc9]

They sent me a 1100mm belt again
However they were very nice and promised to sort ASAP.

[tim wood]

Check your part number , should be
C19525
Not
C19523

Tim

[ianc9]

Yep C19525 that's what I ordered

[rfs1957]

I've always used the standard double-vee belt on my 3.8, and kept the tensioner simply because it was brand new when the car was restored first in 1990 and looked quite trick

Now that I've fitted a smaller pulley onto my Dynalite alternator/dynamo to speed it up by 25%, after a slight fear that traffic jams with headlights on might cause a charging issue, I'm at max-adjustment on the belt-tension and definitely need to find a shorter belt.

I understand that the C19524C is a 1010mm belt, and would guess that 990mm - less 20mm ? - would sort it ?

Has anyone ever come across a belt-supply that classifies belts by length rather than part-numbers ?

I'm going to ask Powerlite-Dynalite, and if they can help I'll post the answers here.

[mgcjag]

Gates belts.....they give part number(Inc circumference) & give a product code....Steve

[rfs1957]

Steve, could you perhaps post the link you found to our kind of belt from Gates ?

I can't find a single one that corresponds to our width and 2-V section, never mind a range of lengths to choose from ?

Thanks.

[mgcjag]

Hi Rory...I didnt look for a particular belt....I just answered your question....re length Inc in part number...Gates are a major belt supplier...if you cant find what you want then message them.....Steve

[Gfhug]

https://www.gates.com/us/en/power-trans ... belts.html

[rfs1957]

Finding simple V belts is indeed a piece of p—s, and I wouldn’t clog the Forum if I hadn’t done some work myself.

But I cannot find a single example of a DOUBLE-vee, on any belt-manufacturer’s web site, that is remotely compatible with the Jag profile.

Remember, it’s not at all the same as having pulleys with two identical grooves that are designed to run with two identical belts, of which there are effectively legion.

And the vaguely two-vee modern profiles are NOT the same as ours.

Is it ‘cos I is French ? (Ed - are you sure about this ?)

[mgcjag]

Hi Rory...have you looked at Gates power brand belts...multiples of single V bonded together....I really would give them a call......their techs may well have cross referance numbers....Steve

[rfs1957]

What we are lacking is the post-1961 equivalent of this - brillliant and erudite ? - essay on XK belts that I stumbled across.

https://www.bobine.nl/jaguar/02-engine/ ... jaguar-xk/

I feel his preambule speaks volumes about finding alternative belts :

To complicate the problem of finding the correct belt for the Jaguar XK even more, fan belts have been (and still partly are) developed and manufactured according different (inter)national standards. The most important ones are BS3790 (or an earlier version of that standard) in the UK, the “Standard for Light-duty or Fractional-horsepower V-belts” of the Rubber Manufacturers Association RMA in the USA and the German DIN 2215 standard for Classical V-belts. Today all V-belts are ISO standardized and practically all manufacturers in all countries adhere to these standards. But unfortunately this does not help as the original 1950s fan belt dimensions have been modified into “something close” but certainly not identical.

and that one can probably substitute 1960's for 1950's in his concluding phrase.

Angles, pitch between the vees, these are all things that matter.

The closest I can find from the "Belts from Gates" route throws up belts that have a 19mm pitch between the vees, whereas ours are about 8.50mm, and are 13mm thick against our 7.50mm.

https://industrialbeltdrives.com/gates- ... powerband/

Alternatively, they have ones that are 19.80mm wide - ours are 16mm - with a pitch of 8.33mm, which, even if you were prepared to ignore such critical dimensions in the interests of a roadside botch, would still not help you much as the available lengths are either 1016mm (too long) or 953mm (way too short).

https://www.gates.com/gb/en/power-trans ... 00000.html



All these belts are designed for identical sheaves that are effectively just stacked up next to each other, be it 2 - 3 - 4 - 5 sheaves wide, and are therefore nothing like the profiles we find on our cars ; they are called "banded" belts because they are just a succession of single belts, with a common backing "band", amongst other things - I read - so as to reduce flapping and noise





It's clear from looking at the dimensions of the sections of the belts, and the pulleys, that we are dealing with an architecture that corresponds to none of the current norms - and why would they, when they were designed 65 years ago.









Research continues

[mgcjag]

Hi Rory....have a look here post 12.. contact Greg Bradley he says he has the twin V belts..but i assume not a shorter one that your after..Steve https://forums.jag-lovers.com/t/is-a-w- ... ary/430505

[rfs1957]

Encyclopedia-Steve you will henceforth be known as ..............

Thanks for that nugget, have sent him an email.

PS - Would anyone have a spare dynamo support bracket C18228 lying around (this is the second-type, from R.1510 onwards) - just a precaution ; if need be I can modify the dynamo position slightly to raise it and effectively push the belt tension back into the mid-range, and stay with a standard belt.

[rfs1957]

From Greg in the USA :

I doubt I will be help because I stock the C19524, C19525, and C24291. I don’t think that will be any different than what you have tried. I believe that the current production is made in 50mm steps so if you need something in between, it will be tough. The belt is special because the angle on each vee section is a different angle than any standard belt. The only Gates belts that narrow and a similar angle are the Polyflex, which need far too much belt tension to work in a car not designed for them.

[JerryL770]

Hi Rory,

No doubt for sticklers for originality a double belt is desired, but I do not think your car is quite "original".

So I wonder why 2 belts side by side will not work. I guess they might have fractional difference in length causing some tensioning difficulty but likely they would even up in service, no? Is section a problem to fit your pulleys?

Just my 2p worth of curiosity.

[Simonpfhc]

PS - Would anyone have a spare dynamo support bracket C18228 lying around

Think I have. Let me know and I’ll send it to you.

[Gfhug]

Andrew (Bowie) and others advocate deleting the tensioner. Can they explain to a bear of little brain how the belt is fitted without removing either the water pump or crank pulley
Edited to add, this is for a Series 2 4.2 engine which has belt from crank to water pump and separate one for the alternator.

Geoff (who is missing the tensioner from OTS project engine)


PS, as has now been explained the tensioner can be done without for the S1 as that only has one belt. I shall still expect Andrew to ship over one of his no-longer-needed tensioners for my S2 to apologise for confusing me

[rfs1957]

Re Jerry's question / using TWO belts.

The pulleys are not designed for two symmetrical belts, as the central land makes for quite asymmetric grooves, hence the inside edges of both belts would collide and prevent either from seating correctly.

Anyway, I think I've raised an unnecessary hare with all this as there are - in my context - other ways around the problem, like tweaking the cradle.

[rfs1957]

And PM sent to Simon.