Rod

“Clarks Garage” website
Initial Tensioning on Belt
1) Pre-tension the camshaft belt by turning the tensioning roller eccentric nut (thin 24 mm or thin 27 mm open end wrench) counter-clockwise until the belt can be twisted 90° using the thumb and forefinger. This should be checked at the midpoint between the cam sprocket and the crankshaft sprocket.
2) Tighten the tensioning roller locknut to 45 Nm (33 ft-lbs). Apply counter-torque to the tensioning roller eccentric nut while tightening locknut to prevent altering the belt tension.

NOTE: Originally, this was the only method of tensioning used on 928’s and 924’s. I know of several shops that have never purchase Special Tool 9201 and use this method on 944’s as well. However, it is very risky and I strongly recommend checking the belt with the factory tensioning gage.
3) 1987 Model and Newer Cars with Spring Tensioner:
* Release the spring tensioner by loosening the locking nut and locking bolt near the spring end of the tensioner.
* Tighten the locking bolt and locknut to 20 Nm (15 ft-lbs)
Checking and Adjusting Belt Tension (All Cars)
Yes, all cars. While some people contend that the tension does not need to be checked on cars with spring tensioners, I would disagree. From experience, I've found that spring tensioners vary from car to car and will not apply the same tension consistently when the spring is released. The spring tensioners seem to get close enough to the 2.7 ±0.3 spec for a used belt to be of little concern. However, the spring tensioner WILL NOT tension a new belt to within the tolerance for a new belt (4.0 ±0.3) unless the spring is released, the engine is rolled a degree or two, and then the tensioner is tightened down. The problem is that since spring tensioners tend to vary, you don't know exactly how many degrees to roll the engine. That's why it's important to check the tension using Special Tool 9201.
1) After the camshaft belt has been pre-tensioned, remove the flywheel lock if installed.

NOTE: Do not install starter until crankshaft bolt is installed and torqued as the flywheel lock will need to be installed again
2) Turn the engine clockwise two complete turns and align the mark on the camshaft sprocket with the alignment tab in the window on the distributor housing (TDC). Verify that the crankshaft is also at TDC by checking the "OT" mark in the window on the bell housing.

3) Turn the crankshaft 10° counter-clockwise. This is approximately 1.5 teeth on the camshaft sprocket.

4) Check the belt tension using Special Tool 9201:
* Pull the lock pin on the tool to release the tension roller.
* Align the drag needle with the gage needle.
* Install the tool on the section of the cam belt between the cam sprocket and the cam belt idler roller. Make sure that the tool's tensioning roller is on the toothed side of the belt.
* Push the tensioning roller against the cam belt until the locking pin on the tool engages.
* Read the tension on the dial.

Tension specs:
New belt - 4.0 ±0.3
Used belt - 2.7 ±0.3

5 a) Adjusting tension on cars with eccentric roller tensioners:
* Adjust the belt tension by loosening the tensioning roller locknut and turning the tensioning roller eccentric nut (thin 24 or thin 27 mm open end wrench) counter-clockwise and tighten locknut. Apply counter-torque to the eccentric roller when tightening locknut to prevent altering torque.
* Repeat the steps above until the cam belt tension is within the specified tolerance. Torque tensioner locknut to 45 Nm (33 ft-lbs).

5 b) Adjusting tension on cars with spring tensioners:
* Release the spring tensioner by loosening the locking nut and locking bolt near the spring end of the tensioner.
* Using a pry bar or other suitable tool, manually compress or release tension on the spring as needed. While holding in position, tighten the tensioner lock nut/bolt to 20 Nm (15 ft-lbs).

NOTE: The intended tool for this purpose is the balance shaft sprocket pin spanner (P9200). The spanner pins fit into two holes on the front of the spring tensioner body.

* Tighten the locking bolt and locknut to 20 Nm (15 ft-lbs).


Balance Shaft Belt Tensioning (All Cars)

1) Determine the amount of belt tension required for the type of belt you have.

Old style belt (15 mm wide) - 2.7 ± 0.3
New style belt (18 mm wide) - 3.5 ± 0.5

2) Loosen the locknut on the balance belt idler roller and move it away from the balance belt. It should not come in contact with the belt while checking the tension or during tension adjustment.
3) Check the belt tension using Special Tool 9201:
* Pull the lock pin on the tool to release the tension roller.
*Align the drag needle with the gage needle.
*Install the tool on the section of the balance belt between the lower and upper balance shaft sprockets.
*Adjust and recheck the belt until the tension is within the specified limits.

NOTE: If you have someone to help you it is possible to adjust the belt tension while the tensioning gage is installed. However, the tension should be checked again after the tensioning roller locknut is torqued.
4) When the belt is set at the proper tension, tighten the locknut to 45 Nm (33 ft-lbs). Apply counter-torque to the tensioning roller to prevent changing the belt tension.
5) 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).
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My Writeup from last time
1) Remove plastic engine guard plate from bottom of car
2) Remove the distributor cap
2) Remove the belt cover – 7 bolts with 10 mm socket
3) Remove camshaft sprocket cover – 3 bolts with 10 mm socket
4) Turn crankshaft CW (as viewed from front of engine looking towards rear of car) to TDC; verify by (a) lining up notch on flywheel with slot on bellhousing (seen from bottom of car), (b) seeing "OT" in window (seen from top of car between engine and firewall), (c) notch on camshaft sprocket lining up with notch on cover. The camshaft sprocket will turn one revolution for every two revolutions of the crankshaft – 24 mm socket
5) Loosen top two bolts on automatic tensioner; the one on the left is the "pivot", the one on the right inside the slot is the "position lock" (can see tensioner spring behind and to the right) – 13 mm socket
6) Use a small pry bar or large screwdriver to push the bottom of the tensioner towards the right (compressing spring). Take care to put the pry bar behind the belt roller and not on it. Hold in position and tighten "pivot" and "position lock".
7) Turn crankshaft CCW a very slight amount to release tension from "front side" of timing belt (section of belt that leaves the top of camshaft sprocket at 2 o' clock). Do this from the top side of the car so you can verify that the timing belt does not jump off the camshaft sprocket. You will hear a loud "click" sound when belt tension releases.
If the belt does slip on the camshaft sprocket, then slide belt off and reposition camshaft sprocket so its mark lines up with the notch on the cover.
8) Loosen top two bolts on automatic tensioner to allow it to again push against timing belt. The bottom of the tensioner will move towards the left due to the spring expanding. If the belt feels too loose, then give the tensioner a gentle nudge because it may not pivot freely (due to inherent friction?). A properly tensioned belt can be twisted approx. 45 – 90 degrees using the thumb and forefinger, checked between the camshaft sprocket and crankshaft sprocket. It is best to check at the midpoint of the belt section if possible. This is on the "front side" or section of belt leaving the top of the camshaft sprocket at 2 o' clock.
When my belt was new the "position lock" bolt was positioned approx. halfway in the slot.
For my used belt the "position lock" bolt was positioned approx. ¾ of the way towards the left in the slot.
Also make sure that the timing belt is in the center of camshaft sprocket and others.
9) Tighten top two bolts on automatic tensioner.
10) Turn crankshaft CW two full turns and verify TDC position as in step #4.
11) Check tension on timing belt; if it still feels loose (more than 90 degrees of twist) then repeat step #5 - #10.
12) Repeat step #9 and #10 at least two more times.
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Previous Rennlist or Pelican post
I have set both the belts up by hand for years. On the 944, I always set the timing belt to about 45 degrees of twist for the longest run of belt. The balance shaft belts run loose, and I have always set them to just below 90 degrees of twist on the longest span.
Some people may not agree with this method, but once you have done a few of them, it is okay. You would be surprised at the number of shops doing it this way. At least it will give you a basis from which to check the tension of the two belts.
If you over tension the balance shaft belt, it will start to make a lot of noise.....the real reason it is set looser than the TB.
Remember, if the balance shaft belts comes off, it can get underneath the timing belt, causing it to lose drive, resulting in belt failure, and ultimately valve and piston damage. Better to set it a tad bit on the tight side, then back it off. Also, the belts will seat in over the first 100 or so miles, so it is always good to go back and re-check them

david fracolli

I know I will get flamed for this but I have never used the tool and have always used the "initial tensioning" method on both of my 944's and after a combined 250,000+ miles I have never had a problem.
Dave Fracolli
85.5 944

Flood

Thanks Rod. this will come in handy this and next weekend.