CVT Belt Dimensions

[morgan105]

Hi all,
Just wondered if anyone knows the full dimensions of the drive belts i.e. length-width-thickness-no. of teeth.

Trying to compare with other belt manufacture but need info to continue.

Many thanks,
morgan105

[volvodspec]

considering the fact that these belts need perfect material compound, dimensions and length in order for the CVT to function properly, i'm afraid you will only get a good result when giving a belt to that company.

new aftermarket belts even have kevlar fibre's in them, they need to take a lot of beating!

[nomead]

The material isn't a problem - very similar belts are used in snowmobiles and ATV - with aramid reinforcements and all. It's just that most snowmobile belt catalogues I've seen don't have anything even approximately the size of the Volvo CVT belt. Most are much too narrow. I think the green book mentions 42 mm and 30 degrees angle for the pulleys but nothing about the length. A popular combination in snowmobile belts seems to be 35 mm and 28 degrees, with various lengths (circumference). The Gates catalogue has belt number 6093 which is 43mm wide (1 11/16") but it's only 1105 mm (43 1/2") long which sounds too short. Maybe I should measure my spare (unused) Roulunds belt, but I'll probably f**k it up somehow and get some measurement uncertainties included.

[nomead]

All right, I measured my spare Roulunds belt (marked 46M1340MR 435 as stated in another thread some while ago) - the belt profile was like this :
Top width 46.1 mm
Narrowest width 37.1 mm
Thickness to top of the teeth 17.1 mm

If I didn't apply trigonometry horribly wrong, this gives a sidewall angle of about 15 degrees, but this is just one edge so the total angle for the pulleys is twice that, i.e. 30 degrees - matches with the Green Book.

Top width is what the catalogues use for measuring belt width, so it's something completely different than what is available for snowmobiles. Also, the belt profile doesn't completely match any of the ones listed on the Roulunds website (neither industrial nor agricultural - RMA/MPTA IP-25, ISO 1604, ASAE S 211.4). So it's bound to be a custom order with minimum order quantity requirements.

The circumference was a bit over 134 cm but this is probably due to the measurement being inaccurate. I trust the Roulunds type code already gives that top width as 46 mm and circumference as 1340 mm. The rest of the letters probably tell about the sidewall angle and thickness, but who knows how to decode them?

The number of the teeth was 103 but this should be completely irrelevant information as the pulleys don't have any teeth in them.

I think this should be enough information for searching for alternatives.

[volvodspec]

The number of the teeth was 103 but this should be completely irrelevant information as the pulleys don't have any teeth in them.

that's the problem; details like that are very darn important!!!

those belts need to cope with the vehicles weight, the stresses of up and down shifting on the pulleys etc..

if you apply the kickdown swith the discs of the primary will be pushed outwards maximal, and then you need to make sure that you get the tinyest circulation distance for the belt as possible on the primary!!! same story for maximum upshifting but then it's the other way round.

mess these figures and you won't get the usual performance drive (kickdown) or the fuel economy because the gear setting is off wich makes the b14 produce more revs than needed...

the roulunds belts used on a cvt happened to be used on agriculture vehicles, can't remember on what vehicle and what for.

[morgan105]

Thanks for all the info, i'll look further into it and see if I can find anything. If I do I will keep all informed as there has to be something out there a bit quieter to run with : ) .

morgan105

[Tero Huikko]

I talked to Ammeraal Beltech representative here in Finland a few years a go and he told me that dimensions etc. in the belts can be patented. He suspected that DAF had patent for those exact belt dimensions and now it belongs to Volvo.

We searched almost every belt that they manufactuted and nothing...and the make a lot of belts.
I also remember seeing text "pat.somenumber" in my Roulunds belts.

In about 4 years I haven't found any other belt that would fit and work.
I suggest you contact Danny at dafhobby.nl The volvo belts he has are quieter than the later Roulunds ones.
Roulunds tend to squeak when they're cold.

[nomead]

I fetched a set of spare Volvo belts and they sure look a lot different than the Roulunds belts.

The Roulunds belt has a straight trapezoidal profile while the Volvo (Goodyear?) belt is a bit more rounded. Convex on the top (wide) side, concave on the narrower side, so it's a bit harder to measure things. But here's an attempt.

Top width 44.2 mm
Edge thickness 15.4 mm
Circumference 135.5 cm (along the center of the convex outer surface so the effective circumference is probably less)
Number of teeth: 103 one of which is almost double the width of the rest. Also the gap between the teeth is smaller and the tooth profile is different (flat vs. rounded).

Since the circumference is probably about the same, but the width of a Volvo belt is 2 mm less, shouldn't the Roulunds belt be adjusted differently? But making the pulley gap larger would also change other control parameters, so I'm not sure if that would be a good idea. Maybe I should experiment a bit?

Subjective "feel" : The Volvo belt seems softer, the surface rubber feels sticky to the touch. The Roulunds belt on the other hand feels much stiffer and the rubber surface is also harder and doesn't feel sticky at all.

[morgan105]

I checked the belts again the other day on my wifes car which have had roulands belts fitted. Compared them to the original old volvo belt that I had lying around I found out that the roulands were a lot smaller then the old volvo one. When they were
adjusted to the correct gap it made a mass of noise so I decided to try and do them just by feel instead (like a fan belt), there is very little gap if any on the pulleys now but the change is amazing. There is no nasty noises anymore apart from a slight squeel for about a hundred metres upon taking up drive when cold. They are fine once warm after this and there has been no change in driveability or gearing.

If you have the roulands belts, check you were not supplied with smaller ones that i was supplied with by europarts as the replacement as these were 1150mm long, they work but you can not obtain the 2mm pulley gap as it will give you problems with noise because it is putting to much tension on the belts. The belts are stronger, less sticky then the originals, don't stretch and are a pig to fit. If you want to get them off again you are in for more hassle as they do not have enough length in them to take off the pulleys when drive units are adjusted to their loosest, which will mean having to remove one of the units completly to get the belts off. Never thought about checking the belts for size before I fitted them as car was needed the next day.

From the old volvo one I had I measured it as: 1360mm long, 100 teeth, 44-45mm on outer edge and 35mm internal, depth on sidewall was 16-17mm (5mm flat and teeth 12mm long)(accounted for wear).
When I decide to replace the belts again the ones that are on it now are just going to be cut off, and the new ones will be checked before fitting.

[nomead]

Concrete Evidence!

Top: Roulunds Bottom: Volvo/Goodyear

belt1.jpg (81.49 KiB) Viewed 7343 times

belt2.jpg (73.49 KiB) Viewed 7343 times