TC/Special Water Pump Belt

[chrisbeck]

I've just been down a rabbit hole sourcing a new water pump belt for my '73 Special rebuild. After buying 4 different belts I am now an expert and maybe can save other owners some grief. Vee belts are sized by 'effective length', this being the length of the neutral axis of the belt when fitted to the pulleys. The required cross-sectional shape & size is defined as 'SPZ'. With no tensioning mechanism on the Europa TwinCam this length is critical. I bought a 575 which was too slack, a Lotus parts supplier sent me a 550 which was way too small. I then tried a 562 which was also too small. All the catalogues revealed that there is no standard size between 562 and 575.
I eventually found a belt that fits, it came from one of the major Lotus parts suppliers but would have been considerably cheaper direct from a belt stockist. It's a 562 but is a 'wrapped' belt as opposed to 'bandless' with a smaller profile.
Here's the details: Gates SPZ Super HC. Gates Part No: 9331-00562.
I'm only glad I was fitting this belt with the body removed, it would have been a nightmare to fit in-situ. Hope this helps someone!

[BDA]

There’s a way to bypass all that foolishness. Replace your pulleys with a gilmer belt setup. I don’t know what it costs nowadays so it might not be the economical choice.

edit: chrisbeck, I should make it clear to everybody that I don't think what you did was foolishness. In fact, it's very valuable for many TC owners. I just think the dance that you and many others have to go through to get the right belt for their water pump is silly. As you state, some method of tensioning would be very useful.

[Fotog]

I know you're trying to be helpful.  So I suggest that if you re-size your photos to ~800 pixels wide they'll be easier for us to see and much more helpful.

Easy to do with almost any photo editing software.  MS Paint is especially easy if using a PC rather than Mac.

[chrisbeck]

Thanks, I'll do it now, C

[chrisbeck]

There’s a way to bypass all that foolishness. Replace your pulleys with a gilmer belt setup. I don’t know what it costs nowadays so it might not be the economical choice.

[BDA]

Thanks for showing where they can be had. In the States, I know Dave Bean sells similar kits (209-754-5802).

[Lotuswins]

While the cog belt and pulleys seems a better alternative given there is no tension adjustment, I've found that all these kits are made for race motors which can get away with reduced water pump rpms, whereas a street motor would need to retain the original pulley ratio.  I see in the picture the crank pulley diameter is reduced and therefore it must be designed for a race motor.

I recently purchased two belts for my TC from Classic Team Lotus in the UK and it is indeed a gates brand, p/n SPZ 562.  It appears to be right sized but have yet to try it out.  I currently have an adjustable pulley on the crank so can use other sized belts but the new motor I'm assembling will have the stock setup.

Jerry Rude
4005R

[chrisbeck]

I agree Jerry, I got my belt from the same source (they bought Paul Matty’s spares operation), hell of a price mark-up but I consider it buying knowledge! I don’t think there is sufficient clearance to the cooling water pipe on my chassis for a flat toothed belt, especially as I’m fitting a trigger wheel for injection.

[Dreamer]

< snip >
I'm only glad I was fitting this belt with the body removed, it would have been a nightmare to fit in-situ. Hope this helps someone!

Thanks for pt.# info. Back in the 70's I just walked into my local British car parts guy told him what I needed. He looked it up in his book and then turned around and pulled two down. I asked why and he said it would save me the next time. He went on to say I should always have a spare clutch and throttle cable in the car too.
 
As for installation, as I recall it was quite easy. I got the car up high enough that I was able to roll under it on a creeper. I just looped the belt around the bottom pulley then I was able to walk it around the top pulley.

[314159td]

Gates Super HC is also what the Corvair folks ended at for the "mule drive" fan belt, most other belts are dead in 5k miles but I've had one do 15k fine already.

They're wrapped belts, intended for industrial applications iirc from the Gates catalogue. Less efficient than a standard belt, especially a cogged belt, but they last longer and this tight spot is a good place for them.