It got confusing when internal or external measurements were given but not declared on other sites. Think i’ve only seen the term “stock” in the same sentence as a dimension (once) as 175; which has to be an external measurement right. You did mention 177-178 as standard but i’ve not seen that on any listings. It would fit for me though. So i’ve no idea. Shop websites just don’t provide enough info. JK tell you how big the box it will come in is. Sent from my iPhone using Tapatalk
Technically as long as paired with a particular length belt, they can all turn the fan at the correct speed in relation to engine speed...if anyone knew what that was. A shorter belt will ride lower on the top pulley and turn the fan faster.
On later vans yes - 180 - and marked with a 'D' on the front but most had 170 ish . Could be anything on there now... Sent from my SM-G960F using Tapatalk
It's all been done for you mate , i found pages of the stuff on Samba but they called it "math" .... Sent from my SM-G960F using Tapatalk
I propose then that getting a belt the right length to turn the top one at the "correct" speed in relation to the engine is more important than faffing about with bottom pulleys?
I'm really not getting involved with this - BUT - didn't Mr Parry have some theory that the fan housing was an air reservoir and as long as the fan ran fast enough to fill the 'reservoir' all was well with the world... ? Sent from my SM-G960F using Tapatalk
You can also fit a porsche 356 top pulley and being smaller spins faster ... Sent from my SM-G960F using Tapatalk
call pi = 3 for ease. circumference is then 3x dia. 180 moves 540mm of belt per rev 170 moves 510 say top is 100 dia 300 belt turns it 1 rev 540 belt turns it 1.8 times 510 belt turns it 1.7 times make the top pulley circumference 283, dia 94, by using a shorter belt that rides 3mm lower ... Your 170 pulley turns fan same speed as the 180. Just example numbers of course to make a point.
You did, it was driving you nuts (for a given value of nuts) that's why I'm surprised you attitude for others in the same boat seems to be that it's not worth worrying about?
It’s quite hard to measure, but roughly the outside of my current belt is 88mm (diameter) on the top pulley. Depending on its profile a belt could sit a few mm wider than that. It’s an 8mm thick belt, so that’s 72mm internal on this belt, but the top pulley groove is about 20mm deep (more or less zeroing out as a V). Clearly I know one rotation more than nothing about all of this, but this belt & pulley combo (top & bottom), does seem like a nice fit. Sent from my iPhone using Tapatalk
In a perfect world I would expect a belt running at the outside of the top pulley (so it looks like the bottom one) to turn the fan "fast enough for VW" and any further in would turn it faster which would be "safer". I'm guessing they would have made such an adjustable system somewhat fool proof in that it would then be impossible to make the fan turn slower than intended without the belt riding outside the top pulley which even a grease monkey would see was wrong.
I'm all for helping people out but prefer to establish if there's a problem before wasting time solving a problem that doesn't really exist . I've always been a fan of the 'drive it around the block and see what falls off' method to be honest ... Work with what you've got and go from there Sent from my SM-G960F using Tapatalk
Just want to make sure I actually get round the block! Agreed, this pulley is the easiest (cheapest) thing to change once I get driving again, but it does have a big affect on both performance and cooling. Which i’ll only know from driving it with gauges. An analogy: When I bought this campervan I thought I was buying a well trained & tamed ex-police Alsatian. In reality I was sold a street mongrel, origin unknown, who had been kicked around its whole life and was more likely to kill me in my sleep (literally, as almost everything comprising it was unsafe) than lick my feet and bring me my slippers. Sent from my iPhone using Tapatalk
I'm more of a fan of lounging around contemplating the situation, hoping the obvious will slap me round the chops before I waste any time and money. If you can rule something out by measuring it and calculating, so much better than swapping parts with your fingers crossed for improvement. For instance from the pics and some rough calc above, I'd say it doesn't matter that his pulley may be on the small side because I see it riding that 4-5mm low on the top one. Hence the fan is probably turning as fast if not faster than design and swapping the lower pulley for a bigger one, if one also swapped belts (you'd have to) and coincidentally ended up "riding high" on the top pulley, could actually provide less cooling than currently. So I reckon in this case it's a red herring but I feel happier having roughly calculated that, than I would do swapping parts and trying to create the same driving conditions and judging by oil temp = all too vague and I did my "work" without spending any money, lying in bed with a coffee.
Your “work” is appreciated and I owe you that coffee. Your calculations aren’t far off the actual roughly measured situation. I do apologise to everyone for having to double-check everything with this campervan, but none of it can be simply trusted. I now feel like I can at least do a Lasty and drive it round the block, as is, pulley wise (which is another new subject to me - an interesting one though). Sent from my iPhone using Tapatalk
