rebuilding manual steering rack
07-31-2003, 12:44 PM
#1
Burning Brakes
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Join Date: Sep 2002
Location: Canada, Vancouver area
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rebuilding manual steering rack
My message with hints on rebuilding the manual steering rack disappeared during the last forum upgrade, and I decided to rewrite it:
The general procedure for rebuilding the manual rack is outlined in:
http://www.924.org/techsection/technical.htm
and it applies to both 924 and 944 models.
I rebuilt the rack because it started binding, and it was hard to steer even at speed. The new one is very expensive (CAN$1400), but rebuilt or junk-yard units are available much cheaper. I rebuilt it mostly because I like working on this car.
Here are potential problems: one bushing that holds the horizontal shaft, i.e. the rack, and two bearings that support the pinion. The upper bearing is very strong and is probably OK, while the lower is tiny and I put a new one. I purchased it in a local bearing store (close-ended, needle-type bearing, 14mm OD, 10mm ID, 12mm long). I don’t know where you can buy the bushing… My bushing was the problem: it started binding. I tried sanding it, but overdid it, and slop developed. To remedy, I machined a new bushing on a leith out of delrin. I squeezed it in next to the original, and installed three 4mm bolts with nylon-ended nuts onto the rack to make sure the new bushing doesn't fall out.
If the teeth are worn out a lot, the rack may not be rebuildable. In such case the steering will have slop. Don’t despair yet! There is a metal piece that pushes the rack against the pinion. In my case the rack had a worn-out section at the contact of the rack and pinion. I took a long block of wood, attached a piece of fine sand paper, and polished it even. No slop in the steering now!
Some rebuilders spray paint into the rack housing. Don’t do it! It will probably peel off (as there is grease inside and it’s hard to clean it well), and there is no need for that… The peeling paint is probably the reason the bushing got scratched in my rack, and started binding.
I measured the torque (force) needed to turn the steering wheel by attaching a tiny fishing scale to the steering wheel, and rotating it:
Before (bad rack) – 2.5 kg
After <0.5 kg , and it feels normal now.
You can also measure the torque just by attaching the scale to wise grips grabbing the pinion shaft. Don’t attach the wise grips to the teethed section that goes inside the u-joint of the steering shaft (you don’t want to damage it).
When putting things together, don’t put the lower bearing in through attaching the bearing at the end of the pinion and hammering it in (contrary to the procedure in the web page above). The bearing will not work properly as its housing will touch the pinion shaft, and you’ll get hard steering. Instead, use an appropriate socket with an extension to hammer the lower bearing in. Next, gently hammer the pinion in.
Put some grease at the ends of the rack housing so that the rubber boots can rotate freely during the alignment (you should have it done), and put the boot clamps after (not before) the alignment is finished. Otherwise you risk damaging the boots (guess how I know this).
This is it.
I hope this is helpful.
Warning: the steering rack is a critical component. Don’t attempt rebuilding it, unless you’re confident you know what you are doing!
Stan
P.s. if you find this post helpful, please comment, or drop me a private message.
The general procedure for rebuilding the manual rack is outlined in:
http://www.924.org/techsection/technical.htm
and it applies to both 924 and 944 models.
I rebuilt the rack because it started binding, and it was hard to steer even at speed. The new one is very expensive (CAN$1400), but rebuilt or junk-yard units are available much cheaper. I rebuilt it mostly because I like working on this car.
Here are potential problems: one bushing that holds the horizontal shaft, i.e. the rack, and two bearings that support the pinion. The upper bearing is very strong and is probably OK, while the lower is tiny and I put a new one. I purchased it in a local bearing store (close-ended, needle-type bearing, 14mm OD, 10mm ID, 12mm long). I don’t know where you can buy the bushing… My bushing was the problem: it started binding. I tried sanding it, but overdid it, and slop developed. To remedy, I machined a new bushing on a leith out of delrin. I squeezed it in next to the original, and installed three 4mm bolts with nylon-ended nuts onto the rack to make sure the new bushing doesn't fall out.
If the teeth are worn out a lot, the rack may not be rebuildable. In such case the steering will have slop. Don’t despair yet! There is a metal piece that pushes the rack against the pinion. In my case the rack had a worn-out section at the contact of the rack and pinion. I took a long block of wood, attached a piece of fine sand paper, and polished it even. No slop in the steering now!
Some rebuilders spray paint into the rack housing. Don’t do it! It will probably peel off (as there is grease inside and it’s hard to clean it well), and there is no need for that… The peeling paint is probably the reason the bushing got scratched in my rack, and started binding.
I measured the torque (force) needed to turn the steering wheel by attaching a tiny fishing scale to the steering wheel, and rotating it:
Before (bad rack) – 2.5 kg
After <0.5 kg , and it feels normal now.
You can also measure the torque just by attaching the scale to wise grips grabbing the pinion shaft. Don’t attach the wise grips to the teethed section that goes inside the u-joint of the steering shaft (you don’t want to damage it).
When putting things together, don’t put the lower bearing in through attaching the bearing at the end of the pinion and hammering it in (contrary to the procedure in the web page above). The bearing will not work properly as its housing will touch the pinion shaft, and you’ll get hard steering. Instead, use an appropriate socket with an extension to hammer the lower bearing in. Next, gently hammer the pinion in.
Put some grease at the ends of the rack housing so that the rubber boots can rotate freely during the alignment (you should have it done), and put the boot clamps after (not before) the alignment is finished. Otherwise you risk damaging the boots (guess how I know this).
This is it.
I hope this is helpful.
Warning: the steering rack is a critical component. Don’t attempt rebuilding it, unless you’re confident you know what you are doing!
Stan
P.s. if you find this post helpful, please comment, or drop me a private message.
08-04-2015, 08:36 AM
#5
Former Vendor
