Was reading on V-belts while preparing for belts replacement. Found a paragraph in Kirby Palm's book that explains how one can easily decipher belt sizes by looking at part numbers.

Then, I checked what different manufactured offer for '86 XJS and discovered something interesting:

Bando:
1. Fan and idler V-belt: Part Number: 3-310 (width 13mm, length 31.0”)
2. Water pump and power steering pump V-belt: Part Number: 3-415 (width 13mm, length 41 1/2”)
3. AC and Air Pump V-belt: Part Number: 3-590 (width 13mm, length 59.0”)
4. Alternator V-belt: Part Number: 2-335 (width 10mm, length 33 1/2”)

Gates:
1. Fan and idler V-belt: Part Number: 9-319 (width 13mm, length 31.9”)
2. Water pump and power steering pump V-belt: Part Number: 9-425 (width 13mm, length 42 1/2”)
3. AC and Air Pump V-belt: Part Number: 9-600 (width 13mm, length 60.0”)
4. Alternator V-belt: Part Number: 7-335 (width 10mm, length 33 1/2”)

Duralast:
1. Fan and idler V-belt: Part Number: 17-320 (width 13mm, length 32.0”)
2. Water pump and power steering pump V-belt: Part Number: 17-425 (17-320 (width 13mm, length 42 1/2”)
3. Air compressor V-belt: Part Number: 17-595 (width 13mm, length 59 1/2”)
4. Alternator V-belt: Part Number: 15-335 (width 10mm, length 33 1/2”)

ACDelco:
1. Fan and idler V-belt:
2. Water pump and power steering pump V-belt: Part Number:
3. AC and Air Pump V-belt: Part Number: 17-600 (width 13mm, length 60.0”)
4. Alternator V-belt: Part Number: 15-335 (width 10mm, length 33 1/2”)

There is a universal agreement on the width (10mm for alternator and 13mm for the other three) and on the length of the alternator belt (33.5").

But for other belts the sizes differ across brands! The difference can be as big as 1". I believe that both Bando and Gates mentioned that they are OEMs.

Maybe 1" is not that big of a difference because the tension can be adjsuted, but, still, one would assume that manufacturers who claim to be OEM would agree on the sizes of the belts they are producing?

Anyway, I thought I post it here just in case somebody finds this info useful when researching what V-belts to get for replacement.

 

As the decades roll by and specs get transferred from one medium to another, over and over, and application listings are 'rationalized', things eventually get garbled. It's a fair bet that nobody at Goodyear or Gates is checking for mistakes in their listings for belts for old Jaguars....although they might respond to mistakes reported from the field.

Many many moons ago I was a parts manager at a GM dealer. The listings/specs for belts were a mess; full of inaccuracies.....and this was manufacturer info, not yet polluted by aftermarket translations!

As an aside I generally buy OEM Jaguar labeled belts. They are surprisingly inexpensive and, so far, have always fit

Cheers
DD

 

If OEM means (as I believe it should) an Original Equipment Manufacturer (or supplier) back when the car was built by Jaguar Cars, then I would be amazed if some or perhaps any of your listed brands were OEM suppliers to this British vehicle manufacturer.

Amazement turns to outright laughter when I note firms who have arisen in the past 20 years . . . who claim to be OEM suppliers to cars 30 or more years old! Not suggesting this in the cases you quote . . . but I also find that the Jaguar branded belts are some of the least expensive genuine parts. As example, the super long serpentine belts on either my XK8 or S-Type are on a par with the bog-common standard belt on my Ford 4WD.

Cheers,
Ken

 

OEM would be somethkng like Continental or so, some European manufacturer...

Regarding the lengths: V-belts are rarely made specifically for one car. It is easier place the parts you want to fit in the engine bay and then measure the needed belt length and as a manufacturer, get in some prices for the equivalent lengths. And as these engines have really long tensioner rods (the tensioner rod length is amazingly long) you can get away with nearly 10 cm longer belts etc, if you are prepared to use some of the tensioner...

 

Continental? Perhaps so . . . but all that I have seen in genuine Jaguar Cars, Coventry, UK, packaging . . . then British Leyland (BLMC) packaging . . . thence back to Jaguar Cars packaging . . . have all been stamped with the distinctive yellow brand logo of DUNLOP . . . a name familiar across Jaguars for being the recommended OEM supplier of their tyres also from the '50s to '80s. Yes, later cars vary.

In any event, the data and comments regarding length are helpful, but your market's rendition of "width" as a 2 or 3 (or 7 and 9, or 15 and 17) for 10mm or 13mm (really? mm? for an imperial length v-belt?) may be confusing to most who are used to the section profile being "A"or "B" etc . . . this "alpha" being the lead-off in our part numbers for v-belts. We should note also the fact that lengths are mooted to change from imperial to metric in appropriate markets . . . thanks eternal for the belt tension adjustment already noted.

Cheers,

Ken

 

I agree.

Over the years Jaguar has surely used several vendors for many items, and consumables such as belts being a very likely example.

Speaking generally, not necessarily Jag-specific here, a new part factory number often indicates a switch from one vendor to another. Often, 'backordered' parts are the result of a vendor contract expiring before a new vendor has been brought on board. If a car builder has manufacturing/assembly plants in several geographic regions it might use several vendors for the same part to streamline logistics and distribution.



The term "OEM" has been so abused and misused over the years it is now almost meaningless. Often it is used to suggest that the parts looks, fits, and operates like the original; that is, it isn't a "universal fit" type product but a "pattern part".....even if the manufacturer never supplied parts to Jaguar.

A good example of how complicated this can be become is the coils used on X300 4.0 liter cars.

The coils used by Jaguar on the assembly line were bought from Lucas but made by Diamond Manufacturing. Lucas simply bought them from Diamond and applied a "Lucas" sticker.

Nowadays you can buy a Lucas-labeled coil for your X300....but it isn't made by Diamond Manufacturing so it isn't truly the "OEM" coil....but Lucas truly was the OEM supplier to Jaguar for that part. OTOH, with some effort, you can buy the true OEM Diamond coil but, heh heh, it won't have "Lucas" mentioned anywhere!

I don't know what vendor Jaguar is now using for that coil. That is, if your ordered a coil from Jaguar I'm not sure what you'd get. But ...some speculation follows here...for a period of time a few years ago of time Diamond Manufacturing was in legal trouble and apparently had difficulties with production. As a result, Jaguar might have switched to a different supplier....let's call it Dwyer Manufacturing. In that case, Dwyer Manufacturing can rightly claim the title of being the "OEM supplier" but it is not supplying the true OEM coil !

This leaves us a situation where Lucas, Diamond, and Dwyer can all rightfully call themselves the "OEM supplier".....but only one provides the true OEM part.

Cheer
DD

 

Facelift cars used Dayco belts as OEM. Had both the Jaguar logo and Dayco logo on the belt when I replaced the seemingly original belt off of my 96.

I replaced it with a Gates brand, and boy was that one longer. Not that the tensioner couldn't make it work, it was just noticeably larger than the original belt.

 

Replacing all 4 belts today... (in fact old belts are already out and it looks like they were made by Continental)

Question: How to properly set the tension? The Haynes manual says 4mm under the pressure of a thumb... Well, that's not very informative. Depends on whose thumb and what kind of pressure that thumb applies, right?

Any other tips on properly setting the tension?

 

Too tight is far worse than a bit less tight, as it knocks out the bearings. If reasonablr thrumb pressure can deflect the middle of the belt run by 1/2 and inch, that is plenty tight enough. If you get a bit of squealing in use, just a tad tighter. Thoroughly clean and degrease the pulley Vs before refitting the new belts.
Greg

 

Just a whole lot of shaking going on. Belt makers make various sizes that happen to fit a lot of applications. Length and width commonality. Car makers design drives and buy off the shelf so to speak. Some may put out spec's to belt makers and buy to fit. Belt maker may have a fit or see enough money to make a new size to spec.


And, in some fashion, belt makers find car maker spec's and correlate their paret numbers to the car specs.


Best bet. Old belt(s) to real parts house, check fit there.


My restored old Atlas lathe uses a belt drive. I made it from a left over Jaguar belt.
Son says the way I mated the ends of the cut down belt by a wire clasp wouold not work. He is right a lot of the time, not this one, it works just .


My way of belt tension is pretty much as Greg said.


My contribution. Avoid belt dressing to shut up noisy belts. it softens them. Failure time advanced.


When I worked in a full service station, my boss/mentor taught me that a chunk of hard hand soap carefully applied to a turning belt would quiet it at little cost and no danger of added wear.


My LT1 uses a true serpentine. Flat with grooves on the inside. drives some pulleys from the inside and others from the outside. Amazingly clever.


My Jeep relies on a v belt, but with serrations on the inner face. Erroneously referred to as a serpentine. Toothed a better name.


Carl

 

I bought one of these on Amazon to check belt tension. Seems to work great!

https://www.amazon.com/Gates-91107-B...s=belt+tension