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Good Morning All,

The speedo reading on my TR is incorrect.

My understanding of the handbook is that the correct mph per 1000 rpm is 20 approximately on 165 tyres. The instrument has been overhauled and calibrated to 1216 cable turns per mile, which is the given figure on the face. This figure is a mystery, as most others appear to be 1180. I recall that my 3a in the 60's read 3000 at 60 in direct top gear and 75 at 3000 in O/D. This is in line with the handbook. However, the current car reads at least 10 mph under the specified figure, indicating approx. 30 at 2000.

The tachometer is correct, having been verified electronically off the distributor and also by the repair shop. Jacking up the rear axle and comparing tailshaft to wheel turns was inconclusive, probably due to differential action. At this stage I presume that the axle ratio is 3.7, but this is not confirmed. The car was originally non O/D but now has it fitted. Given a figure of 1216 cable turns per mile, I would expect to get 12.1 in 17.6 yards, but three tests indicated only 8.7 turns over that distance. Maybe an incorrect driven gear has been installed at some stage and, can any reader please confirm the number of teeth on the specified driven gear?

Would any responding 3b owner please check the figure written on their speedo below the mileage recorder.

Thanks and regards,

John.

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Hello

What is the ratio of your rear axle (4:11 or 3:7 ?)

What is the number printed in the centre of your speedometer ? 740 ?

It means do you have the matching speedometer and rear axle?

have a good day

GG

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A speedo marked 1216 would have been fitted to a TR3 fitted originally with a 3.7 axle and Michelin X tyres. The speedo should have Triumph Part No. 119047, Jaeger ref SNS6319/06.

 

See my article from Newsletter 29, reproduced in Section E2 of the Technicalities CD. It will you a method for determining the actual axle ratio of your car.

 

My guess would be that you have a 4.1, 4.3 or even a 4.55 ratio fitted. The last listed would give you about 16 mph per 1000 rpm in direct top on a tyre of a similar diameter to an old Michelin X. The Works' TR4s used the 4.55 on the 1962 Tulip Rally, but Graham said the cars spent all their time howling along at 6,000 rpm!

 

You haven't mentioned the dimensions of your rear tyres - they are bound to have some effect.

 

Ian Cornish

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Good Morning All,

The speedo reading on my TR is incorrect.

My understanding of the handbook is that the correct mph per 1000 rpm is 20 approximately on 165 tyres. The instrument has been overhauled and calibrated to 1216 cable turns per mile, which is the given figure on the face. This figure is a mystery, as most others appear to be 1180. I recall that my 3a in the 60's read 3000 at 60 in direct top gear and 75 at 3000 in O/D. This is in line with the handbook. However, the current car reads at least 10 mph under the specified figure, indicating approx. 30 at 2000.

The tachometer is correct, having been verified electronically off the distributor and also by the repair shop. Jacking up the rear axle and comparing tailshaft to wheel turns was inconclusive, probably due to differential action. At this stage I presume that the axle ratio is 3.7, but this is not confirmed. The car was originally non O/D but now has it fitted. Given a figure of 1216 cable turns per mile, I would expect to get 12.1 in 17.6 yards, but three tests indicated only 8.7 turns over that distance. Maybe an incorrect driven gear has been installed at some stage and, can any reader please confirm the number of teeth on the specified driven gear?

Would any responding 3b owner please check the figure written on their speedo below the mileage recorder.

Thanks and regards,

John.

 

 

The overdrive you have now got fitted - is it an A type?

Did it come from a TR sports car or a saloon car?

I recall the Triumph 2000 / 2500 used an A type with a different sized speedo driven gear to the TR. (the qty of teeth cut in the anulus shaft may be different too)

 

I would get your speedo recalibrated to match the vehicle axle ratio and tyre size. That would get the whole thing correct. Simple task for you to carry out ratio checks and send the information with your speedo to a specialist.

 

PM me if you need to know how to do the ratio checks as per the Smiths Instruments instructions.

 

Cheers

 

Peter W

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A speedo marked 1216 would have been fitted to a TR3 fitted originally with a 3.7 axle and Michelin X tyres. The speedo should have Triumph Part No. 119047, Jaeger ref SNS6319/06.

 

 

Hi Ian, do you know if the 1216 turn speedo was fitted at a particular point, such as after 5.50 x 15 crossply tyres went to 5.90 x 15 around 1958 ?. I have only seen the 1180 turn S/N6307/04 speedo in 3:7.1 diff ratio sidescreen cars, but I don't know if 3B's were fitted with 3A or TR4 speedos, or whether they differed between the TSF and TCF series.

 

I fitted an 1184 turn TR4 speedo to my TR3A thinking it would suit 165x15 tyres, but note a reference to an 1152 turn speedo being used for the TR4 after 165x15 tyres were offered by the factory. (both with 3:7.1 diff).

 

It's a bit confusing and it would be good to expand on John McIver's post to sort out a difinitive original speedo list for all 3:7.1 sidescreen cars.

 

Regards,

 

Viv.

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Newsletter 29 was a long while ago! I have had a look this morning and I see that I did not state the source of the table (see page E-2 in the CD and attachment below). In fact, I did not mention the table at all in the Newsletter and I am beginning to wonder whether Alan Robinson might have been the originator, for this is not data which I would have held. Another possible source might have been Ian Gibson, but he tended not to have much data on TR5/6 at that time.

 

According to the table in the CD, 1152 was for TR4A fitted with 3.7 and cross-ply 6.95 tyres.

 

No change numbers are noted in the table. However, Alan sent me this week his 40-page index of Service Bulletins, so I am hoping that he will respond if he has more detail on speedos.

 

With a bit of luck, the table may be attached here! Just had a look - it worked!

 

Ian Cornish

 

 

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Ian et al,

 

I don't recall preparing this table although the format is

very similar to what I used to do.

 

You say Ian Gibson didn't have much info on the TR5s/TR6s -

probably I had even less.

 

Interesting looking through the rest of TRAction No. 29 -

all the names from so long ago.

Also includes your excellent method for checking the axle

ratio without counting the teeth.

 

AlanR

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Thanks Ian - very useful.

 

Seeing S/N6319/06 with 1216 turns was fitted to the last 3A's, it was most likely fitted to all TR3B's, as John McIver's TCF series was one of the last sidescreens made.

 

In fact John's 3B is Australia's youngest known sidescreen car, while 1953 TR2, TS65, is our oldest.

 

Regards,

 

Viv.

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The chart that Ian supplied does not list the speedo I have in my '54 TR2.

 

The numbers on mine are "S 628 51 118 504 04" with a turn number of "1180". These are the numbers also on my parts car speedo.

 

Do these ring a bell with anyone? An awful lot of numbers compared to the TRs mentioned so far.

Is there any other master list of speedo serial numbers used by Triumph out there I could check?

 

John B.

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The table is a bit of a puzzle! I have no recollection of preparing it and Alan says it wasn't him - so who, I wonder who it was? Perhaps it will come back to me (takes a lot longer these days!).

 

John B - 1180 for TR2 is the first entry in the table, but with Jaeger SN6319/00 - for TR2 with 3.7 and 5.50/5.90 cross ply tyres (how can that work with two different tyre sizes, I wonder?).

 

Unless we have someone with a Jaeger catalogue or more detailed Triumph data, I think we may have exhausted this one.

However, the Forum does elicit a great number of interesting contributions, so I haven't given up all hope of someone being able to add some pearls of wisdom.

 

Ian Cornish

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Ian C.

Thank you for your response.

At least I have the correct speedo head for the fitted tyre equipment. I am not familiar with Newsletter 29 etc. Perhaps you could email me the relevant section on axle ratios please.

 

Peter W.

Yes, the o/d is an A type and works superbly on all three gears.

I have no more idea than you, of what it came from. The fitment was done prior to my ownership and I am sorting out all sorts of miscellaneous problems progressively.

Thank you, I would appreciate an email of the Smiths Instructions to which you refer.

 

Hi Viv,

I am determined that we will get to the bottom of this. I have emailed Geoff K. asking him of the origon of the o/d if known. I have a N.O.S. driven gear of 15 teeth believed to be for all TR2-3; this is yet to be confirmed.

 

Regards,

 

John

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John McIver:

If you don't have the Technicalities CD (Section E2 is the relevant part), then e-mail me (ifcornish@btinternet.com) and I'll send the article from N/L 29. The Newsletters became TR Action later in life!

Ian Cornish

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Ian C.

An email sent to the address given in your last post has been returned as undeliverable. Could you please verify or send the info. via my profile which has a contact box therein.

Thanks,

John

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The overdrive you have now got fitted - is it an A type?

Did it come from a TR sports car or a saloon car?

I recall the Triumph 2000 / 2500 used an A type with a different sized speedo driven gear to the TR. (the qty of teeth cut in the anulus shaft may be different too)

 

I would get your speedo recalibrated to match the vehicle axle ratio and tyre size. That would get the whole thing correct. Simple task for you to carry out ratio checks and send the information with your speedo to a specialist.

 

PM me if you need to know how to do the ratio checks as per the Smiths Instruments instructions.

 

Cheers

 

Peter W

 

Hi Peter W.

I have contacted the installer of the overdrive who tells me that it is from a TR.

I would be pleased if you could send me the instructions for the ratio check, thank you. My email address is; jadem@internode.on.net

Regards,

John

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