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TR 4 original fan belt size

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J

jimitro

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I had converted my TR4 over to an alternater years ago and am going back to the original generator. I thought I had the correct wide clogged belt in the attic for this at 41 inches in diameter. This seems to be too big as the top mounting bracket does not extend to the upper generator hole mount.
I am using a replacement generator and it looks like a exact match to the original.
Thanks is advance for any help.
 
As near as I can tell, no one actually makes a belt that is exactly the same width and profile as the original. So the first question is what width do you want to use, that almost matches the pulleys? One is slightly too wide (but works fine), the other is slightly too narrow (but works fine).

I'd have to go look to be certain, but I think I'm currently using a Gates TR28386, which is what they recommend and is advertised as 39-1/4" (995 mm) by 7/8" (22mm).
 
I'm using a Gates TR24379 (nice number) which is 3/4" x 38 3/8". That's 19mm X 976mm in new money.

That belt is from Gates' "Truck & Bus Series" in case the FLAPS can't find it.

The 3/4" width may be the narrow one Randall mentions. An advantage with the slightly smaller one is that it is easier to get thru that gap between the fan hub and the steering rack. Depending on the condition of your engine mounts, shims, and other stuff this can be a tight spot. On some cars (mine) it was necessary to loosen the mounts and jack up the engine to change the belt -- I finally shimmed the mounts enough to avoid thia.

BTW - the trick of turning the wheels to get more clearance only work on TR3s -- the rack doesn't move as the wheels turn on a 4.
 
When you are ready to choose the belt, just buy 3 or 4 belts of approxinate dimensions, then return the ones that do not suit you. Auto parts store allow this practice all the time, so I learned when I converted to alternator.

Robert
66' tr4a irs
CT 53788 L
 
Thanks for everyone's help. Will get both Gates belts today and see which fits the best. Good suggestion on the narrower belt to replace without lifting/jacking front of engine.
Cheers
 
Just a fast update on fan belt
Bought the NAPA/Gates #24379 belt yesterday.
Fit perfectly without having to jack up the engine to squeeze between
the cross bar!
Thanks again for the advice
 
I'm curious, can a belt's length change (i.e. stretch or contract) after it has been in service for a while?

I obviously was able to install my current belt (TR28386) but now I cannot seem to get enough slack to remove it. I'm thinking I may have to cut it off and replace with a new one.

Bob
PS: the reason I want to remove it is b/c I suspect my waterpump is making bad noises and I want to run the engine w/o the belt to confirm.
 
RJS said:
I'm curious, can a belt's length change (i.e. stretch or contract) after it has been in service for a while?...
Click to expand...

A belt will stretch a bit -- that's why you re-check tension after it has run 5 or 10 minutes. But I think once that initial period is over it doesn't stretch any more.

Perhaps (since yours seems tight) you had to force it over the pulley to install. Pretty easy to get it on that way if it is a cogged belt but a bit trickier to remove -- may need a tool (stick or screwdriver). Some even wedge something in there and bump the motor. Some VW drivers (not me) can even change the belt with the engine running!

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Geo Hahn

My belt is also 7/16 thickness but the clearance is less than 1/4 in. under the steering rack. Uummmh!

Yes, heard/read how to replace belts but only disassembling a lot worked in my car. No, never damaged!

Thanks.


Robert
66' tr4a irs
CTC 53788 L
 
Just came back from hospital after I tried removing my TR4's fanbelt whilst the motor going.
They succesfully removed the screwdriver from my chest.
 
Rrbbeerrttoo said:
My belt is also 7/16 thickness but the clearance is less than 1/4 in. under the steering rack...
Click to expand...

That was pretty much how mine was. The mounts were nearly new and firm so I added shims (made from big washers) to raise the engine. As I recall 3 washers each 1/16" thick did it. I slotted the washer hole so they could slip into place with the engine raised.

I also shimmed the radiator a similar amount to keep the top hose aligned.

jimstr4 said:
...They succesfully removed the screwdriver from my chest.
Click to expand...

You were lucky, the last guy who had that problem was a lot taller.
 
Geo Hahn

Doesn't adding shims under the engine mount only cause some misalignment in the drive mechanism. I envisioned unwanted strain towards the rear, like transmission mount, etc? I imagine the drive shaft compensated for half of the engine shimmimg change. Do you still own the shimmed TR?

Thanks.

Robert
 
jimstr4 said:
Just came back from hospital after I tried removing my TR4's fanbelt whilst the motor going.
They succesfully removed the screwdriver from my chest.
Click to expand...

:lol:
On a front engine car the "change the belt with the engine running" trick is much easier if you improve access by removing the radiator, but it doen't save much time that way...and you have to be careful not to run the motor too long while practicing the trick....
grin.gif
 
Rrbbeerrttoo said:
...Doesn't adding shims under the engine mount only cause some misalignment in the drive mechanism...
Click to expand...

Good question and one I do not really have a definitive answer for.

Triumph shimmed the engines and radiators as needed. This is what a TR3 engine mount shim was shaped like:

EngineMountShim.jpg


On the TR3 (and early 4s) they usually had to shim one or the other to align the crank hole & crank but I cannot say how much would be too much.

It would seem that a 3/16" rise at the engine mounts would be a very small change (in degrees) back at the gearbox mount.
 
Rrbbeerrttoo said:
Doesn't adding shims under the engine mount only cause some misalignment in the drive mechanism.
Click to expand...
Not enough to argue about; that's what U-joints are for. And you could just as easily be improving the alignment as making it worse.

As Geo says, the factory used shims as well.
 
Gentlemen, thank you for your responses about shims. I will adopt your shim method, confidently. Replacing future belts as I did previously was apparently totally unnecessary, maybe even foolish!
Glad I joined your group.

Robert
66 tr4a irs
CTC53788 L
 
Geo Hahn,

I am attempting to duplicate what you did , but before I do I have more questions.

The engine and frame supports are inclined about 45 degrees. Therefore, any shimming pushes the bottom rubber supports closer to each other ( and up , of course ), possible not allowing the engine footing to drop into the frame supports. Can not see how shimming w/o enlarging engine mounting holes would work.
I appreciate your reponse and your patience with my questions.

Robert
 
The mounts are rubber, and can deflect enough to cover a moderate amount of misalignment. Also the holes are somewhat oversize originally, which also allows some wiggle room.
 
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