View Full Version : TR2/3/3A TR3A Fan Belt Question

01-24-2010, 02:55 PM
HI guys,

Quick question.

Fan belt, cogged or not? Does it matter?


M. Pied Lourd

01-24-2010, 02:57 PM
Cogged. Easier to get on. I've bought from RockAuto in the past with good results.

01-24-2010, 04:58 PM
The cogged bely I got from Moss squeaked real bad. Did not want to wait for another from Moss so I went to my local Napa parts store and it works great and I kept the moss one form a spare.

01-24-2010, 05:34 PM
Dave, I'm told that the cogged belt should not be tightened quite as much as a regular V-groove belt. Something about it's grip on the pulley and the effect on the bushings or bearings.

01-24-2010, 07:55 PM
I believe the original was not cogged, but I much prefer the cogged belt sold by NAPA. It's not actually quite the right profile, but in practice it works very well. Rides just a bit deeper in the pulleys than the proper belt, which made my alternator conversion fit better.

01-24-2010, 08:07 PM
Dave - where are you at on the work at this point?

01-24-2010, 09:03 PM
Hey Tom,

Check out the making progress thread about 5 down....

On to the carbs now.....


01-25-2010, 04:59 PM
Not sure it matters. Original is not cogged. However, I went with cogged due to better availability and the fact cogged is supposed to flex easier, run cooler and last longer. Had the exact same squeaking issue with belt from same supplier above. I tried everything before I replaced it with a (Gates) belt from NAPA. Perfect ever since.

To save the generator and waterpump bearings, I actually install it as loose as possible and still spin those units and not fall off. Generally, that works out to be 1" of motion in the shortest run (b/t generator and waterpump). Factory manual specifies 1" play in the longest run.


Don Elliott
01-25-2010, 07:05 PM
I put a solid belt on my 1958 TR3A in 1990 when I did my full body-off restoration. That belt was from TRF and was marked "Made in Germany". It was a solid belt and only lasted 13,000 miles. These belts are hard to put on and they don't flex around the pulleys as the original ones. The original solid belts were solid and ran fine. Poor quality today. I was on Hiway 115 just south of Peterborough on the way to the Canadian Classic in Burlington at the end of July, 1993 when that solid belt broke. It took me less than 5 minutes to thread on my spare belt which was a Gates cogged belt and which measured 17.5 mm wide. In 2007, that cogged belt had worn narrower - down to 16.5 mm wide and it was slipping in the pulleys. I couldn't tighten it any more because the generator was so far adjusted over that it was hitting the inside if the inner wing. That belt lasted me 80,000 miles. It wasn't broken - it had worn too narrow. So I put on my new spare.

Now to my present spare. I bought a NAPA cogged belt with a nominal 19mm width but when I got it and measured it, it was only 16.5 mm wide. That was the same as the one which was already slipping in the pulleys. So I returned it and bought another NAPA cogged belt with a nominal width quoted as being 22mm. But when I got it, it measured 19,4mm wide at the top of the "V".

Like BOb, I don't tighten them too tightly.

Don Elliott
01-25-2010, 07:06 PM
And this is what the label "mis-reads" on the rear of the package.

01-25-2010, 07:36 PM

Thanks very much for the info everyone.

M. Pied Lourd

01-25-2010, 07:41 PM
So,when you go to buy a belt,ya gotta drag your caliper along now. Geez. Starting to sound like dimensional lumber.

01-25-2010, 07:53 PM
The 28386 is the one I use, at the usual tension. The one I took off of the wrecked 3A did not appear to be worn, but did have some weather checking so I put the spare on the project. One of these days, I need to stop by NAPA and pick up another spare for the next 20 years <<GRAEMLIN_URL>>/grin.gif

01-26-2010, 03:14 PM
The latest cogged one I got from the supplier mentioned above did not fit. I had bought one a few years before with the same part number and it fit just fine in my TR4A but the one from last summer was too short or too fat. I am going to try the NAPA one in te spring.

Don Elliott
01-26-2010, 06:10 PM
I haven't tried the latest NAPA belt, but - thanks Randall - now I know it will do some day when I need to put on my spare. Here's the one I put on in 2007 which I can carried as my spare in the "boot" from 1993 to 2007. I believe I got the info on this fan belt from Bob Shaller and Digger Davitt (bless their TR souls) back about 1994 during a business trip to Phoenix.

01-26-2010, 07:59 PM
According to an old post I saved from FT, TR28386 is the 'new' Gates number for your old 695 belt, Don. I'm reasonably certain this is the same belt sold by NAPA as 25-28386.

01-26-2010, 09:14 PM
According to an old post I saved from FT, TR28386 is the 'new' Gates number for your old 695 belt, Don. I'm reasonably certain this is the same belt sold by NAPA as 25-28386.

And RockAuto gives the specs of TR28386 as follows:
GATES Part # TR28386 {Truck &amp; Bus V-Belt; VA 7/8" x 39 1/8"} $11.77

01-26-2010, 09:37 PM
Hey, thanks for the tip, Randy! Never would have occurred to me to look at RA, even though I've been buying various other bits there. Their service isn't the best, but that's half what I paid at NAPA, and I had to make two trips.

Don Elliott
01-26-2010, 09:53 PM
I paid $27.00 for the latest 25-28386 NAPA fan belt shown in the photo above. Even with the US to CDN dollar exchange, the rest must be for transport up here to Montreal plus profit.