number-1
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| posted on 3/4/13 at 02:55 PM |
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Chain tightness?
Can a drive chain be too tight? I've taken the old one off and replaced it with the same size chain (530 sigma xrs) it's the same number
of links. It is tight! Almost no play at all top or bottom. I'm expecting a bit of stretching on the first track day but is there such a thing
as too tight? It's a mid engine bec
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Peteff
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| posted on 3/4/13 at 03:29 PM |
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Are your differential and your engine both fixed in position ? If they don't move in relation to each other it should be alright, it's not
like on a bike where you have to allow for the swing arm moving up and down.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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minitici
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| posted on 3/4/13 at 03:40 PM |
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As above, the chain can be slightly tighter than on a bike.
However - do check that the chain tension does not vary too much on a complete revolution of the chain and sprockets.
You can get tight spots due to eccentricity of the components.
Remember chain length and front/rear sprocket sizes mean that one revolution does not necessarily mean that all combinations of teeth and links may
not have occurred. There are some on line calculators which can be used to check how many revolutions are required to get back to the start
position.
If you abuse your chain with snatched starts then you can put localised stretch into the chain links and this also makes chain adjustment difficult as
you will get tight/loose spots.
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edsco
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| posted on 3/4/13 at 04:37 PM |
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I had this discussion with Andy Bates not that long ago. Basically his recommendation on new chains is to have circa 15-20mm total travel up and down
at the mid point between your 2 sprockets. So what that means is select the mid point then press the chain downwards. This should total between 7-10mm
deflection of downward travel. Let the chain return to rest position then apply upward pressure and u should have the same movement up. You should try
to retain this tolerance by sliding the diff back to pick up the slack as it WILL stretch, so check it for play after each session until u are happy
the slack remains constant. Simples! ;-)
edsco
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Andy B
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| posted on 3/4/13 at 06:57 PM |
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As Ed said really - too tight and it puts undue stress on the output shaft bearing, causes the chain to run hotter and can lead to quickly hooking
sprockets, too loose and you will get crap gearchanges and lots of backlash on power and braking which will make the car feel horrible. I have always
run my F2, F1sidecars and the Sabres with the aforementioned 15-20mm slack and they have been fine, in fact the first G1 Sabre did two seasons on a
chain
Regards
Andy
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number-1
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| posted on 5/4/13 at 12:00 AM |
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Cheers for the replies lads
I will measure how much movement there is and see if its within the above. Theres a 1mm shim pushing the diff back so it its too tight that can be
taken out and set aside for when it stretches
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