Landseer

Now at top of window (tight side).

Before we put the last cover on,


Center of window?

Or top of window?


Planning to re-tension at 1500 miles or so.

Mrmerlin

go with top of the window, it should be equivalent to 5.0 to 5.2 on the 9201 tool

low side of the window is about 4.2 for the early cars

Landseer

Thank you.

Brad W

You taking over for Andrew on the pop corn? Been a lot of those you've posted today.

Hilton

I think he doesn't realise there's a "Subscribe to this thread" option in the drop-down "Thread Tools" menu at the top of the thread.

GregBBRD

Having just installed my frist "Roger Racing Gates Belt" on an engine, I found that this belt is significantly stiffer than either a standard Gates belt, or a factory Porsche belt. The numbers that I was getting from my 9201 tools were very strange...and I would guess that Roger's new belt needs a higher tension number than any belt that I've seen before.

While I don't have nor have never used a Kempf tool, I'd have to guess that a tool that measures the amount of "twist" would be almost worthless with Roger's new belt.

Was your Gates belt a stock style, or one of Roger's new racing belts?

Anybody else used/have any ideas about tension on Roger's racing belt?

blown 87

Greg, I have a Kempf tool, and measured it and two others against a 9201, all three of the Kempf tools had significantly different readings.

You bring up a point that I never would have thought of, how the stiffness of a belt would affect your belt tension measurements.

Mrmerlin

Chris sorry i did not realize that the new belt was quite a bit stiffer.
If so i would suggest that it be run a looser tension ,
running it tighter may damage the pulleys and the oil pump.
As this is a new application i would also defer to the MFG of the belt for guidance

GregBBRD

We need to wait and see what "Gates" belt he is running. You are "spot on" if the belt is a "standard" Gates belt.

jon928se

I would expect the Roger belt to stretch less than the stock belt. ie compared to a stock belt it would need to be deflected less by the tensioner arm (less turns of the tensioner bolt ) to achieve normal tension equivalent to 5.0 on the factory tool.

When you say the Roger belt is "stiffer" do you mean that trying to bend it (in the way you would wrap it around a pulley) it is significantly stiffer than the stock belt ?

This could cause problems for the 9021 gauge because that measures tension by deflecting the belt over a short distance between two supports and some significant bending stiffness would affect the reading. Note that you are bending the belt in 3 places - over the support pins and over the deflector pin.

By contrast the Kempf gauge measures the tension by twisting - or to put it another way it deflects one side of the belt in one direction and the other side of the belt in the other direction. Again bending stiffness of the belt will affect the reading but the belt is only being bent significantly at one point.

IF (big IF) both gauges bend the belt by the same angle at the deflected point the 9021 will suffer twice the error because the belt has to be bent x degrees at the deflector pin and x/2 degrees at each of the support pins. (The change in angle at the cam pulley and the tensioner pulley using the kempf tool should be small enough to ignore.)

Is the bending stiffness of the belt significant enough to make a difference ? I don't know. A subjective way to find out would be to install each type of belt and adjust to take out all the slack so the belt is straight between cam and tensioner pulleys but not actually stretched - then measure the "tension" with both gauges and see if the readings are significant. There is some error in this as applying either gauge will actually tension the belt slightly but it's about as close as you can get without some actual numbers and physical properties of the belt.

Should the belt be set tighter than stock, same or looser.?

Same
All depends upon how much the stock belt is stretched at stock tension and if this is enough stretch to prevent it ever becoming completely de-tensioned in the unloaded parts of it's path (like between 1-4 cam and 5-8 cam when 1-4 has valves closing pushing the belt towards 5-8cam and 5-8 has valves lifting cuasing the cam timing to retard slightly.)
In theory the Roger belt which is less stretchy could be more susceptible to becoming completely de-tensioned as it will require it to be shortened less to take away the tension, taking just one belt span into consideration. However taking the whole belt into consideration my gut reaction is that this will be balanced by less stretch on the loaded part - thus less cam timing retard and less shortening of the unloaded part.

Tighter
Unless I am wrong about the above and the Roger belt could go slack in an unloaded portion,more tension would be required. This would be bad as it would cause more wear on pulleys bearings etc and in my view would preclude the belt from use.

Looser
maybe so long as the belt doesn't go slack - but how to find out ? I don't know.

Anybody else got any ideas ?

PorKen

James Bailey

The new belt looks and feels and sounds more like plastic than rubber. Seems real tough....not sure what that means for tension.

Landseer

Fairly certain it was a standard Gates belt, but cpayne or Roger can confirm.

danglerb

Honda guys seem to have the most experience with the Gates Racing timing belt, and seem to like it, say it has zip stretch, but use a different type of tensioning system I think. As long as its "snug" I think I might be more concerned with over than under tension.

aaddpp

I forgot about the "Subscribe to Thread Option" which, in the end, makes finding key threads easier in the long-term anyway. Thanks, Dave.