968 Balance Shaft belt guide pulley
11-02-2012, 12:34 PM
#1
968 Balance Shaft belt guide pulley
Folks,
Installed a Timing/Balance shaft belt kit from Contitech last night and am confused about how the balance shaft guide pulley is supposed to be adjusted. The Contitech instructions seem to say that the guide pulley should be adjusted for .02 inches of clearance between the guide pulley and the belt on the lower balance shaft sprocket, but seems to me it should be adjusted to the upper, seemingly unsupported run of the belt from the lower tensioner to the upper balance shaft sprocket (that section of the belt goes by the water pump pulley and would seem like it is likely to vibrate/flex/hit that pulley). Right now, the pulley is set close to the balance shaft sprocket per what I think the directions said to do, but it is 1/2" or so away from the B/S belt on the section that goes by the water pump pulley. Should the top part of the B/S idler be in contact with the B/S Belt? Is it that I need to turn adjust the cams on the tensioner and idler pulleys in a different direction?
Clark's Garage says the following:
"Adjust the balance belt idler roller such that the clearance between the roller and the belt at the lower balance shaft sprocket is 0.5 mm. This can be done with Special Tool 9207. I normally use a 0.5 mm feeler gauge. When properly adjusted, torque the locknut to 45 Nm (33 ft-lbs)."
I can't find the Contitech instructions online anywhere or I would post those. However, Clark's Garage has a good diagram of the 968 routing (just note that the idler pulley on the diagram for the B/S belt for the 968 is not labeled - it is the circle just above the lower balance shaft sprocket and is in the same location as the one for the '83 - '86 944 diagram)
http://www.clarks-garage.com/shop-manual/eng-10.htm
Anybody know what the correct adjustment is? Short, direct question is should the guide pulley be just short of touching the upper section of the B/S belt, or just short of touching the belt as it goes over the lower balance shaft sprocket (which looks to be what the directions call for, but seems unnecesary to me)?
Also, of course I don't have any of the proper tensioner tools and the balance shaft belt is whining - other posts say to loosen it somewhat. Is there a good "guide" for setting the tension other than the 90 degree flex test?
Thanks in advance!!
Installed a Timing/Balance shaft belt kit from Contitech last night and am confused about how the balance shaft guide pulley is supposed to be adjusted. The Contitech instructions seem to say that the guide pulley should be adjusted for .02 inches of clearance between the guide pulley and the belt on the lower balance shaft sprocket, but seems to me it should be adjusted to the upper, seemingly unsupported run of the belt from the lower tensioner to the upper balance shaft sprocket (that section of the belt goes by the water pump pulley and would seem like it is likely to vibrate/flex/hit that pulley). Right now, the pulley is set close to the balance shaft sprocket per what I think the directions said to do, but it is 1/2" or so away from the B/S belt on the section that goes by the water pump pulley. Should the top part of the B/S idler be in contact with the B/S Belt? Is it that I need to turn adjust the cams on the tensioner and idler pulleys in a different direction?
Clark's Garage says the following:
"Adjust the balance belt idler roller such that the clearance between the roller and the belt at the lower balance shaft sprocket is 0.5 mm. This can be done with Special Tool 9207. I normally use a 0.5 mm feeler gauge. When properly adjusted, torque the locknut to 45 Nm (33 ft-lbs)."
I can't find the Contitech instructions online anywhere or I would post those. However, Clark's Garage has a good diagram of the 968 routing (just note that the idler pulley on the diagram for the B/S belt for the 968 is not labeled - it is the circle just above the lower balance shaft sprocket and is in the same location as the one for the '83 - '86 944 diagram)
http://www.clarks-garage.com/shop-manual/eng-10.htm
Anybody know what the correct adjustment is? Short, direct question is should the guide pulley be just short of touching the upper section of the B/S belt, or just short of touching the belt as it goes over the lower balance shaft sprocket (which looks to be what the directions call for, but seems unnecesary to me)?
Also, of course I don't have any of the proper tensioner tools and the balance shaft belt is whining - other posts say to loosen it somewhat. Is there a good "guide" for setting the tension other than the 90 degree flex test?
Thanks in advance!!
Last edited by Remotecontroller; 11-02-2012 at 02:26 PM.
11-02-2012, 04:55 PM
#2
RL Community Team
Rennlist Member
Rennlist Member
Maybe these screenshots from the factory manual will help.
In summary:
For the eccentric tensioner roller (the toothed one), you turn it clockwise.
For the idler roller (the smooth one), you want it not touching the belt. You want a gap of 0.5mm on the bottom, 0.1mm on the top. At least that's how I interpret it.
In summary:
For the eccentric tensioner roller (the toothed one), you turn it clockwise.
For the idler roller (the smooth one), you want it not touching the belt. You want a gap of 0.5mm on the bottom, 0.1mm on the top. At least that's how I interpret it.
11-02-2012, 06:22 PM
#3
Cool - thanks for posting this. I think when we did the tensioner, we pushed it counterclockwise so I think the belt is riding higher than it is supposed to and explains why the idler is so far away from the belt.
I think the 1MM thing is that you are supposed to deflect/push down on the top run of the belt to make sure the belt is tight on the lower balance shaft sprocket and them measure to .5MM. I don't think there is a clearance measurement between the top of the belt and the B/S idler once adjusted.
I do think, however, that the idler is meant for the top section of belt to bump against/hit and the .5MM clearance on the bottom is to make sure it NEVER hits the idler.
Thanks again! Pretty sure if I tighten the tensioner clockwise it will fix/take care of my concern!!
I think the 1MM thing is that you are supposed to deflect/push down on the top run of the belt to make sure the belt is tight on the lower balance shaft sprocket and them measure to .5MM. I don't think there is a clearance measurement between the top of the belt and the B/S idler once adjusted.
I do think, however, that the idler is meant for the top section of belt to bump against/hit and the .5MM clearance on the bottom is to make sure it NEVER hits the idler.
Thanks again! Pretty sure if I tighten the tensioner clockwise it will fix/take care of my concern!!
Last edited by Remotecontroller; 11-02-2012 at 06:53 PM.
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JimmyB (11-17-2021)
12-10-2019, 02:16 PM
#5
Hello experts, I am doing timing of 1992 Porsche 968.. from the manual I know that at 0.39 of tappet lift at cyl 1 intake, it should be at tdc(flywheel OTC mark)... Now I have set it at 0.39 for tdc & the cam sprocket rotated( without rotating camshaft) with crank rotated to tdc mark , but while I rotate crank for next round the cam sprocket notch mark is not matching with cover plate mark...if I match the cam sprocket mark with cover plate mark, I can not see flywheel OTC mark at correct position it goes 3 tooth further away( attached pic).
i have special tool for pressurising variocam & I am able to pressurise to 3bar & it is leaking, than I put check valve o-ring & it is not leaking air much( photo attached).
Please let me know what might be going wrong.
