TR2/3/3A Narrow belt conversion. I can't understand why...

[Lukens]

...why I would give up my mechanical fan for the conversion. Yes I understand that I get a harmonic balancer in the deal, but honestly, my 3A runs just fine without one (maybe the fan itself has a slight dampening effect?). And the flat belt presents no problem to me. Several guys in our club are adamant about the benefit. I don't see it.

 

[TomMull]

I agree with you but I generally find myself in the minority. I'd certainly keep the wide belt if you are using the original generator. Tom

 

[Geo Hahn]

I suppose the narrow belt opens the way for an easy change to an alternator - though a wide belt pulley can likely be made to work for about the same trouble.

 

[GTP1960]

...why I would give up my mechanical fan for the conversion. Yes I understand that I get a harmonic balancer in the deal, but honestly, my 3A runs just fine without one (maybe the fan itself has a slight dampening effect?). And the flat belt presents no problem to me. Several guys in our club are adamant about the benefit. I don't see it.

I believe British parts NW offers a narrow belt conversion without losing your mechanical fan.

Your hub fits into there pulley. No dampener, but I believe you are correct ( the fan and extension are dampening enough, especially under the belt tension.)

https://www.bpnorthwest.com/aluminum-pulley-kit-tr3-to-tr4a.html
I have one of these modifications. The pulleys are high quality Bastuck.
The crank pulley will also accept the modified extension offered by VB. (For the poly GT6 or TR6 fan among others)
kit consist of three replacement pulleys & belt




Guy

 

[TR3driver]

Wow! What is your magic trick, to run around in FL heat and traffic, with only the stock fan and no overheating??

The stock metal fan does provide some dampening, due to the rubber sleeves that it rides on. But lots of folks (myself included) find that it doesn't provide enough airflow for stop-and-go traffic in hot weather. And the popular plastic fans don't provide the dampening (or at least not as much). The elusive metal 'tropical' fan does, but they are kind of scarce. Also, the rubber sleeves don't last forever and it is a giant PITA to pull the apron just to change them.

In addition to the reasons given above, the narrow belt should be more efficient I doubt that it's enough to argue about, but if you are serious about vintage racing then every hp (or even half a hp) counts.

And the conversion provides an easy way to get the fan extension out of the way, so you can mount an electric fan. Not for everybody of course, but I really like mine.

Overall, though, I'd guess the alternator conversion is the main reason for most people. The stock generator just is not big enough for a reliable, every day car (especially commuting to work on 2nd shift in cold weather as I used to do). And control box maintenance seems to be a lost art.

 

[Lukens]

Thanks for all your input. If my generator ever goes south, I suppose I'll consider the conversion. In truth though, I have no objection to a generator. I run a set of driving/fog lights in tandem with my regular lights and the generator/battery seem to keep up just fine.

As for overheating... I installed a pusher fan several years ago just because people said it was a must in Florida. No thermostat, just an on/off switch. I doubt that I've turned it on more than a half dozen times and then only to be safe in stalled traffic. I do have a cardboard shroud and no crank hole in my radiator.
I'm taking her to Texas next month. We'll see how my luck holds out.

 

[GTP1960]

I'm taking her to Texas next month. We'll see how my luck holds out.

according to my mechanic & also a technician at Moss, a real advantage of the narrow belt is the roadside "emergency" belt change.

while I never had the wide belt break , ( so I'm really just passing on rumors & gossip), the wide belt is suppose to be a bear to change & a special order item to boot, where as the narrow is easier to change & also stocked at most auto stores.

Anyone have first hand experience on changing a wide belt in a pinch?

 

[Geo Hahn]

...Anyone have first hand experience on changing a wide belt in a pinch?

I've never had a problem sourcing the wide belt at O'Reilly's (it's a truck part I think).

Changing the belt on the TR3A was never an issue (though using a cogged belt makes it a bit easier). Belt change on a TR4 can be a problem as the gap is even narrower and the trick of turning the wheels to gain clearance is no help with the R&P steering.

To address this I added some shims (thick washers) to the TR4 motor mounts to raise the engine a bit creating enough clearance for a belt change. Of course I also had to raise the radiator a similar amount to get the upper hose to line up.

I recall one driver who would install two belts... one on the pulleys and the other zip-tied back out of the way for easy on-the-road replacement.

 

[TR3driver]

I've changed a wide belt on the side of the freeway, on the way to a club meeting, and still got there before it was called to order. As noted, the cogged belt makes it easier (and also lasts longer). Biggest problem had nothing to do with belt width, those lower generator bolts are tough to get at without burning yourself on a hot engine!

Haven't tried buying the belt at O'Reillys, I'll give that a try next time. But I keep a belt in the on-board spares kit, in the center of the spare tire.

 

[TR4nut]

I'm taking her to Texas next month. We'll see how my luck holds out.

Are you going to VTR Regionals? If so hopefully we'll meet up! The pusher fan was a must for me in Houston traffic, but with it I feel quite bullet proof!

 

[TomMull]

I've changed a wide belt on the side of the freeway, on the way to a club meeting, and still got there before it was called to order. As noted, the cogged belt makes it easier (and also lasts longer). Biggest problem had nothing to do with belt width, those lower generator bolts are tough to get at without burning yourself on a hot engine!

Haven't tried buying the belt at O'Reillys, I'll give that a try next time. But I keep a belt in the on-board spares kit, in the center of the spare tire.

I wonder what caused the belt to fail? I replaced my wide belt once when I rebuilt the engine and, as I recall, drove it for ten years (100k miles) without replacing it again. Perhaps my experience is not typical?
Tom

 

[Geo Hahn]

...Haven't tried buying the belt at O'Reillys, I'll give that a try next time.

I should clarify - the belt I got at O'Reilly's is 3/4" wide - I'm thinking the real deal is 7/8" wide. But the 3/4" belt seems to ride properly in the pulleys (doesn't bottom out) and has been trouble free for a very long time.

That belt is a Gates TR24379 'Truck & Bus Series' 'Green Stripe' 3/4" x 38 3/8" / 19mm x 975mm.

 

[TR3driver]

I wonder what caused the belt to fail? I replaced my wide belt once when I rebuilt the engine and, as I recall, drove it for ten years (100k miles) without replacing it again. Perhaps my experience is not typical?
Tom

I've kind of lost track, but that belt might well have been on the car for 10 years. It's also possible it got damaged when the front mount came loose previously, and it took some time for the damage to show up as failure. And like Geo mentioned, it was a Cummins truck belt that rode lower in the pulleys than the correct belt. (Not sure if the Gates belt was not available then, or I just didn't know about it. That Cummins belt was an expensive special order.) Another possibility is that the Cummins belt didn't like the relatively small diameter of the generator pulley; it had steel reinforcements inside (which I didn't find out until it failed).

 

[Lukens]

Are you going to VTR Regionals? If so hopefully we'll meet up! The pusher fan was a must for me in Houston traffic, but with it I feel quite bullet proof!

No, Mr. Nut, We've leaving FL the 6th. Probably be back before the VTR deal.
We're taking the southern routes (back roads) through Florida, Biloxi, New Orleans, Galveston, and meeting an old classmate in san Antonio. After that, no specific plans. I would like to spend a night at a good venue (saloon) in Austin for some country music. After that, I'm looking for suggestions for back roads through middle Texas, Louisiana, Mississippi, and Alabama. Texas Rt 79 out of Austin, to Louisiana Rt 80 looks promising but I'm wide open to suggestions.

 

[HerronScott]

I've kind of lost track, but that belt might well have been on the car for 10 years. It's also possible it got damaged when the front mount came loose previously, and it took some time for the damage to show up as failure. And like Geo mentioned, it was a Cummins truck belt that rode lower in the pulleys than the correct belt. (Not sure if the Gates belt was not available then, or I just didn't know about it. That Cummins belt was an expensive special order.) Another possibility is that the Cummins belt didn't like the relatively small diameter of the generator pulley; it had steel reinforcements inside (which I didn't find out until it failed).

I had a wide belt fail on me shortly after I restored my TR4A in 1985, but I think it was due to age/dry rot. It was a new belt that either came with the car or that I picked up with spare parts along the way and in my youth (and poorness), I didn't even think as to how old it might have actually been.

Belt shredded on the Interstate about 10miles from the nearest city when I was on a date with my girlfriend (now wife). First I found that the pantyhose trick does not appear to work on our TR's with the wide belt. Second, I found that NAPA carried a cogged belt replacement (sorry I don't have the number!). I was able to replace it on the side of the Interstate but it helped that my engine mounts were new and that I had used spacers to insure there was room between the fan extension and steering rack. We carried on with our date a little late and she still married me despite the ruined pantyhose.

Scott

 

[Tropical TR]

On the issue of dampening and the fan's rubber bushings, any thoughts about changes in dampening if poly bushings are used? I got one of the BPNW narrow belt kits last year and it will go onto my in progress car, along with a Macy fan. - Walter

 

[TRMark]

Pantyhose trick, interesting tactic, uh err, repair attempt, yeah, that's what I meant.

 

[TR4nut]

No, Mr. Nut, We've leaving FL the 6th. Probably be back before the VTR deal.
We're taking the southern routes (back roads) through Florida, Biloxi, New Orleans, Galveston, and meeting an old classmate in san Antonio. After that, no specific plans. I would like to spend a night at a good venue (saloon) in Austin for some country music. After that, I'm looking for suggestions for back roads through middle Texas, Louisiana, Mississippi, and Alabama. Texas Rt 79 out of Austin, to Louisiana Rt 80 looks promising but I'm wide open to suggestions.

Sorry Lukens for the unintentional slow response here - working up a pm to you with some thoughts.

Randy

 

[Fat_Dog_Garage]

A harmonic balancer reduces stress on the crank bearings. Wikipedia has an article on it: https://en.wikipedia.org/wiki/Harmonic_balancer

When I was improving my wife's Sunbeam Alpine I initially attached a custom-made crank pulley that had no balancing improvements, and it performed poorly with excessive vibration. I replaced it with a custom-made pulley that had harmonic vibration minimization qualities and the engine is much smoother. The TR4 I have worked on since 1963 hasn't had a harmonic balancer until last year. As expected it's smoother and I expect the main bearings to last longer.l

 

[TR3driver]

A harmonic balancer reduces stress on the crank bearings. Wikipedia has an article on it: https://en.wikipedia.org/wiki/Harmonic_balancer

Funny, there doesn't seem to be any mention of bearing life or stress in that article. What it does mention is the main reason IMO, it reduces stress on the crankshaft itself. Hopefully preventing this: