cambelt tension gauge

[dave macc]

Has anyone any experience of using the Laser 3899 gauge as offered for sale on ebay?
If you have, how do you relate Newton Meters to lbs ft ?
I've just had the cam belt slip two notches on the inlet valvees and spent two days replacing everything before accepting the impossible had occurred!
It apears that during a severe rain storm leaves that had blown into the engine housing got under the belt. The tension was I thought ok at about 80degrees twist ! But maybe its time to buy a gauge.

1937 Dave with 1989 Excel SA
21years and 89000 miles and still going well!
pity about the driver!

[chrisw2811]

Hi Dave,
Sorry, I haven't used a Laser tension gauge as I have an Optikrik.
1 Newton = 0.224 pounds force.
1 Metre = 3.28 feet
1 Newton metre = 0.224 x 3.28 pounds feet = 0.7376 pounds force feet.
Cheers, Chris

[AndyC]

I have a Facom one (a bit more expensive on eBay) and get on fine with that. To compare the Lotus spec aginast the Laser gauge you'd really want to measure the tension of a correctly set belt using both.

Is there anybody near you who could lend you a gage or who could measure a belt and then you measure with whatever belt you choose to use?

[mkelite]

as Andy knows this subject of getting cambelt tension correct has really bugged me. in the end i got one of the 'Borroughs' gauges Lotus used. if your near by me your welcome to use it. although i have to say the Lotus agreed tension on the gauge is 90lbs. for a new belt. i did that and the belt made noises which i presumed after much debate meant the belt was too tight. ( i have been worrying it was other things! ). i have since loosened it a little and the noise has reduced but not completely. however im hoping the belt will stretch a bit more and make me less worried about noises!

there really is only one best gauge to be scientifically correct and thats the 'Clavis' gauge the sonic meter that costs a packet - so borrow one if you can.

p.s forgot to mention some of the other sonic gauges will only work with predetermined belt parameters. eg. if you put an unknown make belt on ur car n test it with eg. a Gates sonic gauge, it doesnt give a correct reading. thats what i found out anyway........

regards all.

DC.

[amarshall]

What sort of noise ? Hope it's not the teeth on the pulleys getting worn and destroying the belt in return...

[mkelite]

i took the car to a local garage and he said the belt was too tight as the obvious noise when i first put the new belt on. he couldnt find or suggest anything else. another guy who came with Andy C, from the 'other' Lotus forum suggested that too. so i loosened the cam belt to approx. 70lbs and it noticably got quieter. but i dont want to loosen it any more. the cam belt tensioner bearing and crankshaft drive sprocket have been replaced too. this is the first time ive replaced a cambelt on a Lotus car and i did the job to the letter. thats why i was suprised of the vrrr noise when you rev the engine a little higher. i thought all sorts as the initial problem was the car shed cam belt teeth. it sat in the garage for ages as everyone told me 'valve guides bent - pistons had it'. i put new belt on as Lotus manual proceedure, she fired up.....wow! then i checked compression almost perfect at 180lbs across all cylinders. ive since been doing this n that to get her back on the road. she recently passed her mot, shes taxed n insured. jus a little of that noise as said. now wanna replace the shocks n road springs and hand car over to wifey so i can press on with our S2.2 Elite. (just tried the springs n shocks but compressor slipped so im pondering!). so any passing by Lotus enthusiasts VERY welcome. regards. DC.