If you send it somewhere I’d suggest you choose a shop west of the Mississippi - in my experience not all shops understand how to recalibrate.
My mechanic uses Nisogner Instruments in NY. West of the Mississippi if you go the long way round.
I just opened an new tread of this specific topic and it’s 1 in and 1.27 out (so step up). The 1:1 angle drive reads too fast so presumably putting 1:27 on will make it read even faster. It’s looking more like a speedo problem I think.
Good luck.
If you scroll up to my photos you’ll see the 1312 unit they attempted to calibrate and the NOS 1120 unit I had to purchase from London to replace it.
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IF… you do look for a shop west of the Mississippi I can recommend Morris Mintz here:
He did calibrate my speedo after I changed to a 2.88 dif and it works great!
Many thanks. I’ll check their website.
Yeah, I wish I had sent mine to Morris. Nice guy and took time to walk me through the steps for recalibration. Certainly knows his stuff.
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I am certain that it was advice from the good people here that led me to look to the west coast.
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I’m hearing you guys. Thanks for the tips.
There is still something not quite right here. In the new topic you created, you have so far received one response, from @WWayman who has indicated that the output speed of the angle drive turns faster than the input. In March 2018, Bill (@WWayman) posted in another thread that he has a 1970 S2 with a 3.54 rear end and that his right angle drive is the 11:14 version, with a 1312 Speedo. As I understand it, you have substituted a known 1:1 angle drive with your current one, and found that the speedo and odo readings remain unchanged at around 27% high. This proves to me, that your current angle drive is also 1:1. It is too much of a coincidence to me that your speedo and odo BOTH read 27% high, and you (according to at least one person’s account) have the WRONG angle drive fitted, which differs from the CORRECT one by 27%. If I had to take a stab, I would say that the correct angle drive is actually a step down 11:14, and that this is BG2402-08/C25547. In support of this stab, I would say:
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If the angle drive has more teeth on the output gear than the input gear, it is a step-down. It is easy to get this confused if you just look at the gears (or maybe that is just me?)
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If you search the archives there are numerous posts on the topic of angle drive ratios, and the only conclusion I could come to is that there is a lot of confusion on the topic for E-Types. About an equal number of posters assert that E-Types use 1:1 angle drives, as 11:14 angle drives, and in one case I’ve found a poster asserting both answers at different times.
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I hope that your situation can be used as an opportunity to, once and for all, determine what angle drive should be fitted to an E-Type, what ratio it is (and whether it is a step-up or down). By being the guinea pig in this case, maybe you can help the community as a whole finally nail this issue down, which seems to have confused us for 15 years at least, and resulted in numerous contradictory posts.
…or, of course, I could be completely wrong… 
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Thanks for helping me think this though. Here are the logical steps we went through.
- PROBLEM: Speedo runs about 1.3x too fast
- Unsure what angle drive is on car but suspect it must be 1:1.27 (11:14) because that would explain the error. If assumption is correct fitting 1:1 should solve it.
- Fitted new 1:1 gear (C25547)
- No change. Speedo still runs 1.3x too fast
- CONCLUSION: Our assumption in #2 was wrong and car had 1:1 all along. This appears to eliminate the angle drive as the source of the speedo problem.
If BG2402-08 is 11:14 (1:1.27) STEP UP drive then presumably it would make the speedo reading faster still.
On the other hand if BG2402-08 is a STEP DOWN drive then it may solve the problem.
QUESTIONS:
- Is there such a thing as a STEP DOWN angle drive for an E-type?
- Wouldn’t this have the ratio written the other way round (14:11) (1.27:1)?
I guess I’m trying to solve this angle drive issue with logic, at this point, rather than having to buy angle drives that I can’t return. I feel as though we’ve eliminated the angle drive as the culprit, though I agree the 1.3x error seems like a coincidence.
I’ll run the BG2402-08 thinking past my mechanic and see where we end up.
You could remove the angle drive and turn the input manually while observing number of turns the output makes.
If you had access to a power drill and could measure the rpms you could check the angle drive end of the speedo cable in the drill and see what speed it read at a known cable rpm. IIRC a 1321 speedometer records 60 mph when the cable is turning at 1312 rpm. A bit of math would tell you if the speedometer was accurate. I know that’s all easier said than done.
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Narrowing down to details:
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How do you know that the angle drive you fitted was 1:1? Did you measure it?
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How do you know that the angle drive you tried was C25547? Was the part number stamped on it (unlikely as C25547 is a jaguar part number, and Jaguar didn’t make the drives; Smith’s did).
Given the apparently contradictory information that surrounds this subject in the archives and elsewhere, I think we will have to be extremely careful to verify everything to make sure that we are on the same page.
Since I last posted, I have verified:
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C25547 is the Jaguar Part Number for the correct angle drive (source: Jaguar Parts List)
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BG-2402-08 is the Smith’s Part Number for the correct angle drive (source Terry’s and Welshes web sites)
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The ratio of this drive is variously described as 1:1 and 11:14. In the case of 11:14 some say it is a step up, some say it is a step down (sources: eBay Ads, Jag-Lovers forum posts)
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Another data point:
Jaguar Service Manual indicates that at 60mph, the engine of an E-Type with 3.54:1 rear end will be turning at 2775rpm.
So, the prop shaft will also be turning at 2775rpm.
The input of the angle drive is driven by a worm drive from the rear of the gearbox, with a ratio of 6/16 (source Paul Cangialosi post to Jag-Lovers a long time ago)
So, the input to the angle drive spins at 2775 * 6/16 = 1041rpm
If the speedo fitted is a 1312 revs/mile (which is 1312 revs/minute at 60mph), the angle drive must output 1312 revs for an input of 1041 revs. That would be a step-up ratio of 1312/1041 = 1.27:1. Bingo!
So, it seems that the angle drive fitted should have a step-up ratio of 1.27:1. The numbers all fit, but the problem is that would make your speedo and odo read even higher…sigh.
Dumb Question: Your car does have the standard 4-speed Jaguar gearbox fitted, doesn’t it? If so, what engine rpms are you seeing at 60mph?
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David says: " Another data point: Jaguar Service Manual indicates that at 60mph, the engine of an E-Type with 3.54:1 rear end will be turning at 2775rpm.
So, the prop shaft will also be turning at 2775rpm.The input of the angle drive is driven by a worm drive from the rear of the gearbox, with a ratio of 6/16 (source Paul C…"
Surely, he must be a rithmetician.
LLO… ummm, Joe
In our time, political speech and writing are largely the defense of the indefensible.
George Orwell
Wouldn’t a rithmetician have said 3/8s?
I think he’s a engineer and he just counted the teeth on the two gears.
Oh, and an economist would have said 48/128ths to sound more precise.
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I’ve got David down as an Investigative Detective. “Data! Data! Data!” cried Sherlock Holmes, "It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.” 
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Yes, standard 4-speed box. Numbers match Heritage certificate. Not sure of revs at 60 will have car back on Friday and will check. Thanks for giving it some though. Greatly appreciated.
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And a Bachelor of Arts graduate would ask; “Do you want that with Fries”
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and then added, “On the other hand that’s 6/16”.
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