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Burroughs or Krikit cambelt meter - Page 2 - Engine/Ancilliaries - The Lotus Forums Jump to content
Mike6

Burroughs or Krikit cambelt meter

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Lotus has specified the acoustic method ONLY for the round tooth belts...

The Facom also uses the acoustic method! If you used it, you'd be developing your own spec.

How many Hz would you tighten it to?

I'm not saying it can't be done, but there is no official spec that is applicable to the trapezoidal tooth belts.

At a minimum someone would have to tighten a trapezoidal belt (actually many) with a known good Burroughs, and then immediately compare that to the acoustic method, many times over, and average your readings. The trapezoidal belt might have a wider spread...

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The DM16 is a mechanical tension measurement item. yes, it works for both square and round, the square belt is (I think from memory but haven't set one for a few years now) slightly thinner so has a different plunger fit in the unit.

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Travis, I hear you on the acoustic method being only good for the round tooth belt. The DM16 is mechanical as Andy states.

clicky for one on ebay:-

http://www.ebay.com/...=item2563bb1cb9

Thanks for the info Andy. I think I may just get me one and have a go.

Incase anyone is interested this is Tim Engle's take on the what to use on a trapezoidal belt:-

since the Lotus gauges

are so rare and difficult to find anyway, perhaps the better solution is to

take the gauge fate gives to you, and re-calibrate it for your own use.

The procedure is surprisingly low tech and easy to do.

The Burroughs procedure for calibrating the gauge is:

Hang a length of the belt style and size to be tested from overhead.

Suspend a weight equal to the target tension from the end of the belt

sample.

Remove the face label from the gauge's dial.

Take a reading on the weighted belt with the gauge and hold it steady,

being careful not to move the dial after the initial snap-release of the

gauge.

Re-apply the face label, taking care to align the index line or appropriate

tension number value with the pointer on the housing.

That's it.

If you start with a rogue eBay "Burroughs" gauge, then doing that

calibration procedure will make your target tension accurate; however, it

may not make the gauge accurate across it's full range. Accuracy across

the full range depends upon the spacing of the label markings correlating

with the internal spring's rate and that varies from model to model. But,

for your own Lotus purposes, you really don't care what the accuracy is at

30 lbs or 160 lbs, since you won't be setting the 9XX's belt there anyway.

You have a very narrow interest.

Think in terms of one target tension (95 lbs) plus a narrow min-max range,

and you can calibrate a variety of Burroughs gauges to work for your Lotus

engine. Using the Lotus OEM blank white label, you could even calibrate

one gauge against both the trapezoidal and HTD belts, painting your own

additional line for the second belt style's tension position.

Or start by making a replacement face label out of white vinyl label stock

available form printing or sign companies... maybe even Office Max.

Find accurate 80, 90, 95, 100 lb weights and good samples of trapezoidal

and HTD belts. Use black markers for one belt style (matching the Lotus

mark that's already there for 95), and another color for a second set of

four marks for the other belt. Each set of four marks will be for:

80, Yipes!, scary, park it. Don't think about driving it

90, normal minimum, ~okay, but tension the belt soon

95, Lotus spec, re-tension a used belt in service

100, I set new belts a little tight to allow for initial stretch

Kent-Moore bought the production rights for the Burroughs gauge and

continues to produce it. Then SPX got involved, so you'll see "Burroughs"

gauges sold under the Kent-More, SPX/Kent-Moore, SPX/Owatonna Tools Corp,

OTC and SPX/OTC labels. Expand your eBay search a bit.

Watch eBay for a Kent-Moore J-26486 cantilever gauge. It "looks" like the

Lotus cantilever gauge, but it has two scales on it... one for a

trapezoidal tooth belt like the Lotus unit, and one for a much larger

trapezoidal belt.

I have one of the J-26486 units, but have not yet checked the calibration

against the correct Lotus tension.... my expectations are low. Spring

tension feels different at the hand grip compared to an OEM Lotus cantilever

gauge I have. Here's the link to an old eBay auction for a rather ratty

example... http://tinyurl.com/6o4bjg.

While I wouldn't use my J-26486 to tension a Lotus belt as it is now, I do

believe it's a candidate for an easy re-calibration as discussed above.

The Kent-Moore J36018 cantilever for the GM Quad-4 engine shows up on eBay

very often; but they're not appropriate for the Lotus 9XX so don't go

there. I've been there, done that, wasted the money.

The correct NON-cantilevered trapezoidal Lotus gauge was a Burroughs

BT-33-86A, but you rarely see them on eBay... with either the generic or

Lotus face labels. However, the Burroughs BT-33-73F / Kent-Moore

BT-33-73F / Kent-Moore J-36660-A / SPX-OTC 6673 / DRAF PN-371 / Ford

T63L-8620-A / Snap-on GA424A / Miller Tools C-4188 / Rotunda 303-015 are

all similar under the skin and collectively, they show up pretty often.

Like this old auction... http://tinyurl.com/6jwx9e

They're usually billed as "universal"; however, they don't give the same

"Lotus" reading as the OEM Lotus trapezoidal unit. But they're close, you

can use a 73F on a Lotus trapezoidal belt and be within spec. Or, they're

a great starting point for the same calibration exercise... make a new face

label, hang a belt with a weight and calibrate it for your own belt.

Regards,

Tim Engel

Edited by GavinS1

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Havent yet got round to putting the cambelt back on - still faffing around with shim clearances but got an opportunity to manually check the cambelt on another Esprit engine. The belt felt really tight and didnt have any give (or twist) at the usual test point. Guess that service stations unless Lotus specialists just tighten them up as much as possible!.

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There is no reason why you cant use the frequecy method on the trap belts but they will have a different frequency to the round belts. I worked it out some time ago and posted it but I dont have time at present to go looking. The frequency method is the most accurate but it must always be done in the same place with the engine position eg 30deg otherwise you will get errors. It may not show up so much on the mechanical setting tools but mainly because of their degree of accuracy. As for the twist method, my experience is it is less accurate than the mechanical setting tools unless you get lucky or one of the few with a calibrated finger.

Cheers

Ralph

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Ralph you calculated it to 114.5hz, which I think is based on the top end of the HTD range. (The range is a fairly generous 100-110hz). Frequency is all I've used for the last 3 years (in preference to a Lotus Burroughs gauge). I choose to run marginally slacker at 112Hz.

Agree - the twist method is dangerously subjective, and I would only recommend for a periodic 'sense check' of a belt that has previously been accurately set.

Edited by 910Esprit

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Great info Ralph and thank you for posting your opinion on the "twist" method. That's been my opinion for years. Ditto what Steve said.

For any newbies that may not be aware of Ralph's background, he has been involved with R&D for a major auto maker for many years and has done extensive work on belt technology...

Edited by lotus4s

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I have used all three - krikit, kent and now the TuneIT...

I could never trust my krikit reading - drove me crazy. bought a Kent Moore J-26486 off e-bay, calibrated it, and then used it for the past 4 years.

I now use a mic, laptop and TuneIT - and have been able to validate the J-26486 against the TuneIT method.

I would recommend the software... but there is a J-26486 on e-bay right now... http://www.ebay.com/...=item336e73b09f

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I purchased a second krikit to compare readings with the one I already had. One read 51lbs and the other read 27lbs!!. I wouldn't trust the krikit.

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I just tried a new frequency analysis app for my Android phone.


I also use this type of software for my work, and it looks like this will be very good for use as a tension gauge for the Esprit 910 with the round tooth belt, and 918 V8 belts.



Speedy Spectrum Analyzer

by Electron Chaos in Android market

 

IMG_4859.JPG





(Note, I have no relationship with the above company)



It has the ability to do a peak hold and will be much easier for you to pick out the resonant frequency of the timing belt.



I just tried it on a small silicone tube, and it was able to pick up that tiny sound (roughly the same freq as the Esprit timing belt too ~110Hz).



I can use some equipment here to check the accuracy of the app.

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Does anyone know the setting when meaasured with a Facom, Laser, Bergen etc?

Replacing the belt on a 1982 Turbo.

 

Thanks

Lars

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Does anyone know the setting when meaasured with a Facom, Laser, Bergen etc?

Replacing the belt on a 1982 Turbo.

 

Thanks

Lars

 

Lars,

 

You should really ask this in the Giugiaro Esprit section.  The trapezoidal toothed belt and pulleys on the earlier Esprits do require some different methods.

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