PSA: Don't blindly trust workshop manual dimensions

[314159td]

I was about to cut tubing for adjustable lower links on a Renault-engined car when I decided to double-check the lengths of the originals. I have 18.89" for the C-C distance in CAD, and noticed Sleurs chose 484 mm (19.055"). This comes from a simple pythagorean theorem calculation based on the workshop manual drawing...but we used the same workshop manual page.

S1/2 Workshop manual, Rear Suspension, Page 12, Figure 12, Dimension 1 confidently lists 18.65" as equal to 487.029mm. In reality, it would be 473.71mm (assuming the inch measurement is the original), which is almost 1/4" off. I believe some of the online manuals have retyped characters where the scans got blurry, that's where this particular error comes from. I've attached a picture from my physical workshop manual below which shows 18.85". My old links match that value (well, the one that isn't bent).

18.85" != 478.029mm still, it should be 478.79mm. There are plenty of other slight inch to metric conversion failures on the same page which can't be explained by rounding going one way or the other, but several are correct so I have no idea what happened there. 1in = 25.4mm was fully standardized well before the 1960s. I'm also unsure which dimension should be considered driving; the metric measurements have an incorrectly matched number of significant figures.

tldr: Original workshop manuals have incorrect inch to metric conversions. Scanned manuals with retyped measurements might have very incorrect values. 

Tried to submit that note to the manual feedback link, which promptly errored out. I should probably crawl and save all of lotus-europa.com offline

[EuropaTC]

tldr: Original workshop manuals have incorrect inch to metric conversions. Scanned manuals with retyped measurements might have very incorrect values. 

I can see how the re-typed scans might contain errors, as for the original manuals it might be down the the period.  In the 1960s/early70s when these manuals were written most engineers were using slide rules for calculations and although you can get 3dp with good quality rules, I'd guess that's why there could be conversion errors.

[4129R]

Calculators started appearing about 1973 IIRC.

[Bryan Boyle]

tldr: Original workshop manuals have incorrect inch to metric conversions. Scanned manuals with retyped measurements might have very incorrect values. 

I can see how the re-typed scans might contain errors, as for the original manuals it might be down the the period.  In the 1960s/early70s when these manuals were written most engineers were using slide rules for calculations and although you can get 3dp with good quality rules, I'd guess that's why there could be conversion errors.

Well...when Steve Veris, Jerry Johnson, Whit Davis, Pete Blackford, and myself did all the scanning and reformatting of the manuals back in '07, mistakes were bound to crop in.  Couple that with the OCR software we were using...as well as scanning what were, at that time, probably copies of copies of the original...quite easy to confuse a type-written "6" with an "8".  Not excusing (we did catch the mistake re the distributor rotation direction) in the original as well as other issues, so in the end, it all washes out.

[EuropaTC]

Well...when Steve Veris, Jerry Johnson, Whit Davis, Pete Blackford, and myself did all the scanning and reformatting of the manuals back in '07, mistakes were bound to crop in.  Couple that with the OCR software we were using...as well as scanning what were, at that time, probably copies of copies of the original...quite easy to confuse a type-written "6" with an "8".  Not excusing (we did catch the mistake re the distributor rotation direction) in the original as well as other issues, so in the end, it all washes out.

As the kids would say "not dissing you bro..." 

Once I'd got a scanner for my PC I did a fair bit of OCR conversions thinking "electronic is the future". But pretty much every page I did would have errors on it, no matter how good the source was. For any small documents it was easier to just make notes and type it up rather than scan, read & compare with the original, correct & save.  I always lost enthusiasm after a few pages of that.

And even now, with a "scan to PDF" function on my current scanner, far quicker scanning and more accurate software I rarely do more than the odd page or article.

So the job you guys did back then was a massive task and personally think some of the PDF copies are excellent.   I have original manuals from Lotus for all my cars but I'll admit that most of the time I use the PDFs you guys did for reference on the PC or if I want a page printed out to take into the workshop.

Brian

[Bryan Boyle]

Well...when Steve Veris, Jerry Johnson, Whit Davis, Pete Blackford, and myself did all the scanning and reformatting of the manuals back in '07, mistakes were bound to crop in.  Couple that with the OCR software we were using...as well as scanning what were, at that time, probably copies of copies of the original...quite easy to confuse a type-written "6" with an "8".  Not excusing (we did catch the mistake re the distributor rotation direction) in the original as well as other issues, so in the end, it all washes out.

As the kids would say "not dissing you bro..." 

Once I'd got a scanner for my PC I did a fair bit of OCR conversions thinking "electronic is the future". But pretty much every page I did would have errors on it, no matter how good the source was. For any small documents it was easier to just make notes and type it up rather than scan, read & compare with the original, correct & save.  I always lost enthusiasm after a few pages of that.

And even now, with a "scan to PDF" function on my current scanner, far quicker scanning and more accurate software I rarely do more than the odd page or article.

So the job you guys did back then was a massive task and personally think some of the PDF copies are excellent.   I have original manuals from Lotus for all my cars but I'll admit that most of the time I use the PDFs you guys did for reference on the PC or if I want a page printed out to take into the workshop.

Brian

Oh, I know Mr. R.  When I was the editor of a magazine back in the day, even after my assistants and typesetter had read over the copy...don't you know when we got the proofs back...there was always a missed comma or some other punctuation error or misspelling.  And this was a tech magazine, to boot. 

The originals were rife with mistakes...thought we got them all.  Guess not, but then it's not the launch codes, so...lol.  As for trusting anything...I look both ways before crossing a one-way street.

[dakazman]

314159td
  Thanks for reporting. I will definitely make notes on changes you pointed out .
Dakazman