TuneIt! for Esprit S1 cambelt?

[ElEsprito]

Hello all, as I'm about to set the tension on my new S1 cambelt using TuneIT!, I'ld like to make sure that the specs for doing do are 110Hz at 30 degrees BTDC. Correct?

TIA!

Dennis

[Vulcan Grey]

Doesn't work on the square tooth S1 belts, only the later round tooth HTD belts.

THe Spec will most likely be wrong at 110HZ at 30 BTDC.

[910Esprit]

Travis, who says it doesn't work and what would prevent it? - Its all I ever use on my trapeziod belt. I run at just a tad higher frequency at 112Hz.. (personal choice through empirical evidence). As you say Dennis, 30 BTDC, cold and job dove. Get it checked at a dealers (or forum member....) afterwards if you are uncertain.

Steve

Forget to mention - check the frequency between auxiliary and exhaust pulley.

Edited October 29, 2010 by 910Esprit

[andydclements]

All you really need is somebody to tension a belt using the Lotus approved method and then use Tune-it to get the reading from that belt, OK a few measurements using different belts may be best, but I guess once will be close enough.

[Vulcan Grey]

The specification and procedure provided by Lotus is for the round tooth HTD belts only.

If you want to develop a spec for your trapezoidal belt, then do what you want. But the idea is not to blindly follow the HTD spec for a trapezoidal belt.

Without the correlation, as you mention, there would be no way to tell if 110HZ, at 30BTDC on a trapezoidal belt, would end up damaging the belt...

Lotus did not provide this correlation, and actually specifically worded the specification against it...

Personally I have compared Tune!it to a similar app on my Android phone, as well as the Lotus approved Clavis gauge and a Gates Krikit KR1!

Edited October 29, 2010 by Vulcan Grey

[ElEsprito]

Thanks guys. So the key in this case is the type of belt I have. The teeth on my belt are very square, but then I've never seen a rounded tooth belt, so can't tell for sure.

Looks like I'll need to buy a gauge as I'm not going to take chances by driving to the dealership with a belt that's maybe not tensioned correctly.

Anybody got a link to info on S1 tensioning using a gauge, or are the specs to be used the ones that are in the shop manual?

Rgds

Dennis

[910Esprit]

A 'clavis' type gauge can be used on any rubber/composite belt. As Its based on a mathmatical formula. 30btdc is to give a consistent tension between inlet and exhaust pulley. This is true of all belt types.

As Andy suggests, if you choose to check the results against a new belt set correctly with an accurately calculated Burroughs gauge you will get 100% repeatable and consistent results. I have compared tune-it to my burroughs gauge....

[ralphw]

I haven't the time to go looking but I did calculate the frequencies for the Trap belt elsewhere on this forum. A bit of digging should find it.

Regards

Ralph

Edited November 3, 2010 by ralph

[Paul Coleman]

Here's some stuff on timing belts, if it's any use...

Timing belts #1

and...

Timing belts #2

Paul.

[innocenti]

I'm facing the same issue. I also have a S1 square tooth belt that I want to tension right as I think it has to much tension based on noise and twist test. I've also read that the 110Hz is only for the HTD type

Maybe there is someone on the forum with a correctly tensioned square tooth belt and a Kriket 1 that wants to check the resonance frequency of the belt?

Simon

[ralphw]

Last year on this forum we had these discussions and I calculated the frequency for the Trap belt (square tooth) at 114.55Hz. For reference the HTD is 110Hz

Cheers

Ralph

[910Esprit]

Lifted from an earlier post by 'Ralph' resident belt expert....

NB - in my earlier post I suggested testing between exhaust & auxilliary - I should have said inlet & auxilliary (should have looked at my own avatar)...

From the above lifted from the Stevens Technical Room (Thanks Georgio) some simple mental arithmatic suggests that the tension for the Trap belt is 114.55Hz

eg 4*142*L(trap)�*F(Trap)� = 4*154*L(HTD)�*F(HTD)�

L is the same for both belts and F(HTD) is 110Hz

Therefore

154*110*110/142= F(Trap)�

√13122.535= F(Trap) = 114.55Hz

[ralphw]

Thanks Steve, was just looking for that.

Cheers

Ralph

[ElEsprito]

Thanks. Not sure what the essential knowledge is behind the calculation though? What is the key logic?

Dennis

[ElEsprito]

So, I've used TuneIt! and one of my SingStar mics today and tried to set the tension of the belt. What I found is that the mic registers pretty OK. However, taking the measurement changes the actual belt tension. So after hitting the belt with a spanner the first time after turning the engine to 30 degrees BTDC , the tension in the belt changes (Frequency drops from 114.5Hz to approx. 113 Hz). So for comparison, I always turned the crankshaft 2 revs ( to be sure) and then performed the same measurement. After a bit of such fiddling, I got a pretty consistent measurement of around 114Hz, provided this was the first measurement.

I have a Krikit on order from the US, so will check the tension with that once I have it.

Thanks for all your help

Dennis

[ralphw]

[Thanks. Not sure what the essential knowledge is behind the calculation though? What is the key logic?

Dennis ]

Dennis

The equation has been used to tune belt tension using Clavis gauges for 22 years and has given excellent results. If you want to know a bit more about the subject, try the following site.

http://www.clavis.co.uk

Cheers

Ralph