Ive just made up the st170 denso alternator brackets and now need a belt.

Does any one know if the length on them is measured on the back of the belt or the rib side or through the middle ?

I used to pop to Halfords buy one and try it and pop back latter and swap it for a shorter/longer one. They have bugger all in stock these days.

cheers

Take a measurement from bottom of groove of pulleys with adjustment of, go to Halford and if its wrong they will change it for you. It took me two attempt's to get it right.
They do belts in 10mm increments.

[Edited on 22/5/13 by madteg]

If you have difficulty finding exactly the right length because you have a bespoke set up, have a look at seller "doctor_car" on e-bay. They sell virtually every possible length, although it can be a bit of a challenge filtering the search results.

I've just been playing with bits of washing line and think I have enough adjustment for something between a 6pk1225 and a 6pk1238.

My local Halfords used to have hundred's, last time I looked I would say there was less than 20.

Got mine from here.

http://www.camskill.co.uk/m28b0s2592p0/Cambelts_Auxilliary_Belts_Drive_Belts_and_Fan_Belts_Dayco_and_Gates_Poly_Rib_Belts_-_6PK_Belts

Well Halfords was a waste of time.
The local auto factors didn't have one and even Mlilfields in Peterborough didn't have one.

Not even that rare a car that it fits.

I used to buy and return belts until I had the right one, now I save old ones or get them from the scrapyard and keep cutting them until they are spot on, then unfurl and measure or take them to the autofactors. Also easy to split with a knife if they have too many ribs on.

Do you have a GSF near you? They were very helpful when I was doing this. I ended up with a 5PK rather than 6, which is a bit of a blessing to be honest as the cam belt cover can be in the way of a 6 if you go over the top of the FWD engine mount

Ive got a place to get one in for me for tomorrow, just hope ive measured well. Ive gone underneath with the extra idler.

I tried that initially but I ended up in the strange situation of having to move the alt closer to the engine to tension it?! It also only adjusted over a very small change in effective belt length. I ended up going over the mount, around the alt and then back over the top of a smaller idler pulley to get a good range of adjustment. It could be that my alternator is mounted in a strange fashion though!

Try measuring with a flexible steel tape measure and then knock off about 10mm!

Also consider 5pk and 4pk also work just as well as a 6pk and give a few mm of alingment if need be

Surely an exact length isnt needed, as long as its withn a few cms the adjuster should take care of the rest?