Rear Shock Installation Koni's (LONG) - Saab NG900 & OG9-3 Bulletin Board - Saabnet.com
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Rear Shock Installation Koni's (LONG)
Posted by Dean (more from Dean) on Mon, 10 Sep 2001 22:12:32
Rear Koni Install
drs_install <- seach key word
one 3/4 open ended wrench, and one thin one to clear the other jamb nut (or 19mm)
one 16mm or 5/8" open ended wrench
some sealant may be needed, non hardening mastic suggested
17mm socket, driver and or breaker bar and a torque wrench for 46 ft-lbs
small vice grips
exacto knive or equivalent
penetrating rust preventer
anti seize or grease or oil for the rusty bolt threads
paper towels and a wet rag to clean shock towers if they have been leaking
floor jack or equivalent
With thanks to all previous posters, especially Baab.
The job took me 2:20 including time searching for things that I think my wife hides on purpose, but she calls it cleaning up. :)
Cut the intents out in the trunk with an exacto knife. A big utility knife might not cut the corners easily. At the lower extremes, cut all of the way down until the cut gets out of the indent, otherwise it will not fold back easily and might otherwise tear.
The bottom bolt has a 17mm hex head. It might be tightened up with some rust on the threads. Baab suggested leaving the tires on the ground, but I found this difficult. My old shocks at 129000 miles still had their gas pressure. It was difficult to push the shock up to get it out of its mounting flange. Lying on you back and reaching out at the same time did not help. If you do bench presses for fun, you can leave the wheels on the ground if your pec's will clear the chassis.
So undo the bottom bolt first. The gas pressure on the bolt will likey make removal difficult. Perhaps rasing the chassis part way will make removal easier.
Loosen the top mount but do not remove just yet. perhaps back off the nut 1/4" or until the rubber bushing is freed up. So the bottom of the shock will move easily side to side.
(You need a 16 mm open end wrench, and a 5/8" might also work very well. The top of the strut has a reduced diameter with a flat which is only 6mm across. A small set of vice grips will do nicely. A larger tool might be getting in the way and could also block the view. The nut is nyloc and will take a while to get undone. DO NOT undo both shocks at once!! One at a time.)
Now with the bottom bolt removed and the top loosened, jack up that corner of the vehicle. The axle will lower relative to the body, and the axle weight should pull the bottom shock bushing our from its mounting flange. If you have both shocks undone, you will have the axle dropping more than you want and I don't know what might get dammaged then.
If the bottom does not disengage, it should respond to a hammer from underneath. One it is clear move to one side and lower the vehicle. Now back to the trunk and finsh removing the topside. If things get stuck, as you get it free, that end of the axle will drop a bit. The shock on the far side will limit its travel.
Baab brought up the issue of sealant, and reusing it. My 95SET did not have sealant and there were very obvious signs of water intrusion. I used a hi tech 3M rubber sealant puddy. Some kind of not hardening mastic material would do well. Clean the adjacent areas of the body, top side and bottom side. Obviously Saab became aware of this problem after 1995 production. The old upper buffer has a steel bottom, so it was a steel on steel affair, so the buffer it self was not able to help much. The buffer reloads may have been low as well, especially after things settle in.
I put some sealant between the shock shroud and the threaded shaft, and the bottom steel buffer support washer. The conave side goes to the rubber! Then some between the rubber and the support washer to keep water from getting in that interface.
Raise the vehicle again, and insert the strut. The Koni gas pressure is even higher and pushing that up to intall into the mounting flange is difficult. Rest the bottom of the shock bushing on the flange. Now insert into the flange. It will be tight. The flange probably has distorted inwards to match the old bushing spindle. The flange may also have some stamping burrs that don't help. I needed a phillips screw driver and a 1/4" x 6" socket extension to move the spindle through the flange bold hole once things got roughly lined up. Getting the threads started was a bit of a chore. I adjusted as above with a screw driver to look in side and that helped a lot. Depending on the state of rust etc, you may want to have previously cleaned and have oiled the bold and the axle threads. Get the bolt almost home but do not tighen it. The bolt had self chasing threads to facilitate putting the bolt into the painted threads in the axle. I see these as potential for cross threading. So be careful. If you mess up the threads you are in a world of hurt.
Now lower the vehicle and as you do this make sure that the raised section of the lower buffer is properly in the hole in the chassis. I don't know why that hole is elongated. Now apply the top rubber buffer with some sealant between it and the chassis, but not between the rubber buffers themselves. Now put on the steel washer concave side to the rubber, then the 1st thin 3/4 hex nut. Run that down a ways, then add the second nut. Jamb the two against eash other to lock in position. You will need a thin 3/4" or 19mm wrench for the lower nut, and a standard one for the upper. Getting a thin 3/4" wrench is the most difficult task that you have! You need to bulge out the buffers a bit but don't over do it. I have three threads showing after locking things down. Note the drawing in the instructions. Note that there are almost no instructions at all.
Now with the vehicle lowered on the wheels, torque the 17mm lower mounting bolt to 46 ft-lbs. This will lock the bushings steel spindle so that is will not move. Spray some penetrating rust preventative on the bolt head and on the inner sides of the flange to seal the spindle from water penetration. Note that if the bushing was torqued down with the vehicle raised, then lowering the vehicle would wind up the rubber element. In some bushings where the rubber is vulcanized in place, tightening in the wrong position could be damaging. It might very well be that this bushing would allow the steel spindle to simply turn in the rubber bushing. But now you know the proper approach. The steel spindle should never move in its bolted postion.
Baab reported that the lower spindle length seemed too long. I measure both the old and new ones with calipers. Both were the same length: 36mm. I removed the paint from the ends of the steel spindle, as paint should not be in a bolted joint. That made the spindle 1/8 mm shorter. The mounting flange closes under the bolt load. It is a welded fabrication, so it should not be a surprise if one is tighter than the other. They are probably all a bit wider in the factory before the bolts are applied. The shocks seem like they need to be in a slighty different posture when trying to get the lower bold threads to line up and get started. So the flashlight to look down the hole really helps see whats going on. I needed a hammer to help help get one lower bushing into its flange.
I hope this helps with planning etc.
I have the shocks on the softest setting for now. Front shocks on the weekend I hope.
posted by 209.172.2...
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