Evidently you can also buy a similar (same) kit from Triumph Rescue

I first used Gates TR24379, but it's fairly short (3/4"x38.5"). I switched to Dayco 24380 which gives slightly more length, but I'd like to get more space between the alternator and engine block. The next Gates 3/4" belt is TR24400 which is 40 5/8" outer. If you drop down to 22/32" width, you can get a 39.75".

The Gates Green Stripe II belts are segmented/cogged, which gives flexibility which means less sideways pressure on the alternator, and this is a good thing, as Triumph belts are often much tighter than they need to be, causing belt wear and alternator/generator bearing wear, eventually causing a metallic whine (which can come from a worn belt!).

There are also belts by Dayco and goodyear, and often they have "interchange"/interchangeable part numbers where the actual length can be off by a 1/2" or so (one belt is 38" inner diameter and one is 38" outer diameter). On the Triumph there is so little room for error considering the amount of play you need to have, space you want between the alternator/generator and the engine due to heat issues, and the lengthening of the belt over time. So a 38" outer diameter belt is just too small, but a 38" inner diameter can just barely work.

So I found a number of spec sheets for various belts. Often the part numbers are related to belt dimensions, but not always in the same way and not always consistently. For Goodyear/Continental, the part number XXYYZ has XX as width in 1/32", YY as outside length and Z is supposedly 1/8" length. Having said that, Goodyear claims that 24377 is 37.5", and 24393 is 39". So I'm not sure how they figure the fractional lengths. Maybe this is effective length which is at the top of the cogs, but not the outer diameter? Then for Dayco, the YYZ is *inner* length in decimal fractions: YY.Z" (rounded), i.e.: 24398 is 39.75" inner (34.8 rounded, and with an outside diameter of 40.39" - too big).

Here is a table with the close candidates I have found, I make no guarantee as to the correctness of these measurements, they are generally from the manufacturers, and it seems they aren't fully clear on their own specs.

Other alternator conversion methods:

• Delco 10Si with a wide pulley from an agricultural machine supplier
(suggested trimming of mounting to get alignment right)
• Nippon-Denso 27029-61011
• Moss motors has a full kit (including mounting arm/hardware) for $320

• Go down to your local alternator rebuild shop and ask for either part number 1214P or 201-01005. - John Kallaus
• FWIW, I found a source for the wide pulley for my ongoing conversion to a Delco alternator. The vendor is Quick Start Electric Products (http://www.alternatorparts.com/Alternator_brackets_2.htm) - Dean Mericas
• I just bought a 2-1/2" pulley that fits a GM or Fiesta Alternator from a place in Wichita KS. (Phone # 316-265-8990) It is made for the wide belt. - Kent Schrack

Alternator Sourcing

10SI/12SI part numbers

It's easy to change the mounting - pull out the 4 bolts holding the two halves together, but do not pull the two halves apart. If you separate them by more than a 1/4" or so, you will pop out the bushings and they are hard to get back in. Instead just rotate the halves and bolt them back together.

12SI alternators were built with 56amp, 66amp, 78amp, and 94amp maximum output ratings. 12SI has (better) plastic instead of metal fan and a ridge on the front of the alternator + fan to ensure that air must come through the alternator body. 12 o'clock mounting puts the electrical connector up against the engine and is unlikely to be found.