Which fanbelt?

[TimG]

I want a spare fanbelt for my TR3A but cannot read the numbers on existing belt. I read there are wide & narrow belts mine is 16mm wide & toothed Vee so which belt? My car is dynamo equiped.

Edited April 22, 2023 by TimG
Extra info

[RobH]

That sounds like a modern AVX section cogged belt Tim (-or it might be an industrial BX which are available in a wider range -), so is not the original type and you won't get it from Moss or Rimmers etc.  I use one of those as it is more flexible than the original stiff wide belt and far easier to fit.  They are available in a multitude of lengths so you really need the numbers to get the right one for you.  I use a 965mm inside length one  (BX-17-965) but I have a home-made alternator set-up so yours might need something slightly different.  If you really can't read the numbers, measure the belt but beware that AVX belts are numbered for outside length while BX ones are for inside length. 

They are available from most bearing suppliers, e.g.:

https://www.bearingshopuk.co.uk/belts/v-wedge-belts?belt_section_size=46739&belt_smooth_cogged=46748&p=4

or

https://www.totallybelts.com/collections/avx17-v-belts/section_avx17-17-5mm-wide

Edited April 22, 2023 by RobH

[Bfg]

For what it's worth.. I find the cogged belt slightly smoother running.

Background ;  As a matter of course I changed my TR4A's wide fan-belt for a new one soon after I bought the car. I simply didn't know how old and perished the existing one was, and as all other rubber parts were perished and the car's tyres 27 years old - I considered it prudent to change it.   I kept the old (solid) one as a spare. 

  

Just recently, after some 3000 miles of driving on the new one, I've swapped back and now use the old  WFLENNOR Germany cogged belt. The photos are instructive insomuch as the plain belt is holding the triangular run of the pulleys, even after being removed.  Perhaps this stiffness goes when the belt is hot, but otherwise it may attribute to the belt flapping (as it does have some weight) ..rather than it just spinning out as a circle inscribed by its three pulleys. 

At the extreme right of the second photo you can just see how the solid belt's profile is rounder, whereas the outside face of the cogged belt is slightly concave. It is more pronounced when the latter is fitted. However, this may be because the prior-owner ran the belt much tighter than necessary, or else there's a slight difference in V-angle, &/or in the design of their fabric reinforcement.  In any case, as that photo records, each belt is the same size - but the cogged belt sits further into the pulleys.  If it is of consequence to you car, this relates to the dynamo being 8 or 9mm further out on its clamp bracket. 

The solid belt does feel a harder compound and it is less flexible.  I also think that its join (to make the belt a continuous loop) is more pronounced, ie., a bit lumpier and harder still.  Possibly that may be felt as a vibration as it goes through the pulleys, which is perhaps  unkind on the water pump and dynamo's bearings.   This is difficult to assess even at tick-over speeds. 

I did have a water pump failure when its pulley worked loose, but that was because no woodruff key had been fitted. I then also had a dynamo failure, but that may again be coincidence ..and better attributed to heat from the exhaust down-pipe (I have since fitted a heat shield).  In short, I cannot say if the solid belt made any difference to their final demise. 

NB. from what you and Rob says, your car's fan-belt width x length is different to that on my 4A, but the principles behind what I write are equally applicable.  Anyway it is perhaps food for thought.

Pete

 

 

Edited April 22, 2023 by Bfg

[RobH]

20mm wide cogged belts don't seem to be available in the UK Pete. I wonder where yours came from?   Stockists only seem to have 17mm as the widest.  17mm sits lower in the pulleys than the standard belt but works OK.  

[TimG]

OK thanks for the info, I'll have to fiddle around to measure the outside length while fitted.

[BlueTR3A-5EKT]

If you buy a new belt, fit it to your engine and put the run in/stretched belt in the spares stash.   If required it will be easier to fit an used stretched belt than a new one.

 

Peter W

[TimG]

Peter that was my plan. I had a 1973 Dolomite 1850 that used to eat fan belts, lasted about 8k miles.

[Z320]

The Flennor works very well on my TR4A.

Two things are interesting about:

#
It‘s a German product, years ago I wanted to buy a second on (no real need for).

This was not possible at Germany, so I bought it from the UK as a NOS.

I gave Flennor a phone call - „yes, it was a product only for the UK market“.

#
A typ 20 is MUCH too big for your small pulleys (not smaller than 160 mm recommend).

Cogged it works well anyway. Mine is in the car since the restoration in 1992.

Ciao, Marco 

Edited April 25, 2023 by Z320
was, not is

[Bfg]

Thanks Marco, and also Rob,   My car was also restored in the 1990's so perhaps its Flennor belt also originates from then.  

3 hours ago, Z320 said:

A typ 20 is MUCH too big for your small pulleys (not smaller than 160 mm recommend).

Just to clarify, are you saying the 20mm wide belt is too wide for the TR4A or for Tim's TR3A.?   It seems to fit fine on my car with the outside flat face of the belt sitting 1 or 2mm below the rim of the dynamo and water pump pulleys, and 5 or 6 mm below the rim of the crankshaft pulley.  I can think of no advantage for it to sit further down in the 'V' but I am glad to learn.  

Pete

[Z320]

Sorry, „it is too big“ in the sense of „too massiv“, „too stiff“.

A type 10 or 13 would be better (narrow belt).

But you see how this components forgive even a faulty construction,

even the wrong wedged pulley gap.

All good.

Edited April 25, 2023 by Z320

[Z320]

The type 20 belt is recommended to use on  pulleys not smaller than 160 mm to avoid damage on the belt by to much bending.

Our 4 cylinder TRs all 3 pulleys are smaller than 160 mm, it’s the wrong belt.

Question: why is there no type 20 belt shorter than 900 mm available?

This makes no sense on two pulleys with 160 mm diameter, even if they are very narrow to each other.

Edited April 25, 2023 by Z320
4 cylinder TRs

[Bfg]

Thank you Marco,   I shall look out for narrower belt then.

Pete

[Z320]

As told before,

it‘s just interesting to know, but works anyway,

no need to change anything on my TR4A

[mikeh]

On 4/22/2023 at 9:25 AM, RobH said:

That sounds like a modern AVX section cogged belt Tim (-or it might be an industrial BX which are available in a wider range -), so is not the original type and you won't get it from Moss or Rimmers etc.  I use one of those as it is more flexible than the original stiff wide belt and far easier to fit.  They are available in a multitude of lengths so you really need the numbers to get the right one for you.  I use a 965mm inside length one  (BX-17-965) but I have a home-made alternator set-up so yours might need something slightly different.  If you really can't read the numbers, measure the belt but beware that AVX belts are numbered for outside length while BX ones are for inside length. 

They are available from most bearing suppliers, e.g.:

https://www.bearingshopuk.co.uk/belts/v-wedge-belts?belt_section_size=46739&belt_smooth_cogged=46748&p=4

or

https://www.totallybelts.com/collections/avx17-v-belts/section_avx17-17-5mm-wide

I've taken the same approach as Rob and am running a BX35 cogged belt with a standard dynamo set-up & original pulleys on my TR4. It's far easier to fit than the 'old style' belt, runs well & is widely available. Dimensions are 959mm outside and 889mm inside (or 37.75" & 35" respectively).

Regards

Mike

 

[Z320]

BX = typ 17, cogged

[billy l]

For anyone interested I have two new old stock original fan belts for sale please message me if interested. Cheers, Bill.

[TimG]

Further investigation the belt is Goodyear (unreadable) PG718. I have only found equivalents on South African sites where the car came from. An Isuzu belt is listed.

http://crossbelts.com/beltcrossreference.html

I failed to measure to outside run of the belt fitted I dont have enough hands & ran out of time trying to take it off to measure.

[Andy Moltu]

Or fit a narrow belt conversion?

Easier to change although perhaps less likely that you will need to at the roadside.

[Kiwifrog]

On my 3a I run a 20x900 LI Flennor belt and have done so for over 10 years. It is a notched wide belt that I bought from the local factors.  I still have a Dynamo and run a wide belt
 

I notice on autodoc Uk they recommend the Continental solid version for TR4 at £11:43

https://www.autodoc.co.uk/contitech/7120280

Edited June 4, 2023 by Kiwifrog

[TimG]

At last I have had a chance to measure the outside length  of my fan belt its 957 so it seems I need a BX35 cogged V belt with outside length 958mm. however I cannot get the old belt off which looks to be in good condition. My car has had a rack & pinion steering conversion & there is insufficient clearance between the the rack & the start handle dog on the crankshaft pulley nut. Even if the nut will loosen I doubt there is room to clear the rack. Maybe I could grind/file/cut the teeth off the dog As I will never need it as there is no hole in the rad for the handle.

[Z320]

If it works, why change it?

As a spare belt you could buy a „ crocheted“ one.

Browse for „Gliederkeilriemen / Power Twist Plus“

Ciao, Marco 

Edited June 27, 2023 by Z320
Photo added

[Ralph Whitaker]

16 hours ago, TimG said:

At last I have had a chance to measure the outside length  of my fan belt its 957 so it seems I need a BX35 cogged V belt with outside length 958mm. however I cannot get the old belt off which looks to be in good condition. My car has had a rack & pinion steering conversion & there is insufficient clearance between the the rack & the start handle dog on the crankshaft pulley nut. Even if the nut will loosen I doubt there is room to clear the rack. Maybe I could grind/file/cut the teeth off the dog As I will never need it as there is no hole in the rad for the handle.

 

Tim, that belt looks to have been running very low down in the pulley. Maybe you could do with a wider one. To change it you may have to undo the engine mounting bolts at the front and jack the engine up slightly. For emergency use do as Marco suggests and buy some laced belting.  I once tried the old wives tale of tying stockings around the pulleys as a get me home repair, but it didn`t work as I used nylon stockings and they soon melted, I think it only works with silk stockings 

Ralph

[Z320]

IMO

the failure of a fan belt is much more discussed on forums than real likely.

Apart from that I have a spare belt always in the car

[TimG]

I decided to go for B Section Power Twist Plus V-Belt (17mm) - 1 Mtr (BB-97396) from bearingboys.co.uk, it arrived today. I watched the fitting video, maybe I wont need to use it.