Belt Tension at rest vs. driven

[Sempyder]

So put a new belt on and aligned it and set tension per the service manual. 450 +-150N.
So I had set at 460-470N on the mic gauge. After I went for drive 1/2 mile 0-100plus mph and back. Re set mic gauge and it read consistently at 620-630N waited 15 mins rechecked again... consistently around 580N a hour later rechecked 460N on the money. Each time I checked with the sonic tension gauge I completed measurements 10x.

A little curious about the science of what is going on here. Any thoughts?

Sempert out,

[Chupaca]

all settings are cold with the difference of on the ground or in the air but regardless most of us use the Kricket gauge for setting the belt tension. The manual refers to the sonic gauge (expensive) but for most of the older units we are between 120 and 200 on the kricket. I run about 160. Now as for having measured the tension after ryding....never done it but imagine there will be a difference...seems things heated up would tend to loosen rather than tighten as yours did...

[Sempyder]

all settings are cold with the difference of on the ground or in the air but regardless most of us use the Kricket gauge for setting the belt tension. The manual refers to the sonic gauge (expensive) but for most of the older units we are between 120 and 200 on the kricket. I run about 160. Now as for having measured the tension after ryding....never done it but imagine there will be a difference...seems things heated up would tend to loosen rather than tighten as yours did...

I thought the same about the heat, Can the heat change the sonic wave but tension has not changed? and I also thought it would stay in range. I know a lot of people use kricket (krikit? I thought) I'm fortunate enough to borrow a sonic tension gauge but i would think the kricket would respond the same. Next time you ride check tension afterwards I'm curious if the weight pull stays the same after a warm up.

BTW. I'm heading to Martin Speedway Friday night for 1/4 mi passes again. See if I can't beat my 13.6 from a couple years ago.

Be safe. I'm

[BLUEKNIGHT911]

I have NEVER heard of anyone who had a problem with a drive belt that was on the loose side ( even very loose compared to BRP spec ) ..... However I have heard of fried BEARINGS if the belt is too tight ( BRP specs were frying bearings until they changed them ) so take your pick ...... mine is very loose compared to BRP specs....... Mike

[wrb3004]

Hi Mike, when you say very loose what do you have it set at? This spring I had the dealer install a new Altimax rear tire and when I checked it was set at around 210#. I have read many posts about belt tension and not sure at this point what the correct spec is for a 2015 RT. I have loosened it to around 140#. At the same time I am having a heck of a time with the alignment. The belt wants to ride either all the way to the outside or at the flange. Can't seem to get any in between. I have an appointment with Doc at Spyderquest to adjust it but I am still working on it.

What is the BRP spec for a 2015 RT?
What is the secret to get the belt aligned?

[BLUEKNIGHT911]

Hi Mike, when you say very loose what do you have it set at? This spring I had the dealer install a new Altimax rear tire and when I checked it was set at around 210#. I have read many posts about belt tension and not sure at this point what the correct spec is for a 2015 RT. I have loosened it to around 140#. At the same time I am having a heck of a time with the alignment. The belt wants to ride either all the way to the outside or at the flange. Can't seem to get any in between. I have an appointment with Doc at Spyderquest to adjust it but I am still working on it.

What is the BRP spec for a 2015 RT?
What is the secret to get the belt aligned?

#1. I measure mine with tire on the ground, I think it's a better measure of REALITY .... My rear tire is NEVER off the pavement while I'm driving the Spyder , so why would I want to know the Tension that way ... plus it's a pain in the butt to raise your Spyder just to check the tension which rarely changes ( much )............................. #2. 170lbs .............. #3. The secret is DON'T worry about it !!! ... the belt moves all the time while you are driving the Spyder, I watched a video that a guy did showing the rear sprocket while driving .... the belt was moving back and forth on the sprocket....... Mike

[wrb3004]

Thanks Mike. Are you going to Spyderquest?

[Firefly]

Any reason for a new belt?
I've been told that with new belts you'll get different readings even by just rotating it a bit. This is why they say to take readings in 3 different places. The belt will take thousands of miles to 'break in' and give more accurate readings in all positions.

Good luck at Martin. When I get mine back from the dealer I'd like to go do that sometime.. perhaps a Spyder showdown is in order..... ;-)

[BLUEKNIGHT911]

Thanks Mike. Are you going to Spyderquest?

I'm going to try ................ Mike

[Sempyder]

Any reason for a new belt?
I've been told that with new belts you'll get different readings even by just rotating it a bit. This is why they say to take readings in 3 different places. The belt will take thousands of miles to 'break in' and give more accurate readings in all positions.

Good luck at Martin. When I get mine back from the dealer I'd like to go do that sometime.. perhaps a Spyder showdown is in order..... ;-)

Firefly,
I'll send you a message with my contact info Showdown is in order!