These Saab Bushings Aren't Playing Along Nicely

"Urambo Tauro" (urambotauro)
09/04/2018 at 12:30 • Filed to: Saab 900, project, wrenching

I must be doing something wrong.

In preparation for the chassis repairs on the Saab, we removed the control arms and springs. Since there’s a press at our disposal, and OE-style bushings don’t cost much, we really have no excuse not to change the bushings.

LEFT: old control arm bushing RIGHT: new control arm bushing

We had some initial doubts, as the new bushings didn’t look like they were going to fit. But that was just a misunderstanding of how they work. It turns out that the “cone” shape on the ends flattens itself out as the inner part is compressed, making it look much straighter once installed.

If they would just go in straight.

We again threw together a DIY solution to the Saab special tool, this time a special driver to keep the bushing aligned as it’s pressed into the tube. It lines up almost perfectly. All that’s left is for the large tip of the bushing to compress enough in order to slide through. And since it is rubber, it’s pliable enough to do just that. (Which is more that I can say for the old bushings, which were not badly cracked, but they had hardened to the point that they had a tendency to tear during removal. The new rubber flexes much better.)

But while the tool keeps the inner sleeve of the bushing straight, the rubber keeps hanging up on one side, going in. It seems like just a little extra oomph will force it to pull through and right itself, but the bushing seems to stretch too far down into the tube before that caught edge will follow the rest of the bushing.

By the time it’s finally forced through, the rubber has pulled itself away from the inner sleeve that it was bonded to, and in some cases the rubber has actually torn, or leaves part of itself hanging up inside the tube.

New bushings installed, but somewhat mangled. Could they still work? Probably, but I don’t like it.

We’ve been using silicone spray to lubricate it, maybe we should have used soap instead? I know better than to use petroleum-based grease on bushings, but maybe the sili-spray isn’t the ideal solution here. It does seem to be awfully slippery, though. Not sure if my choice of lubricant is really the problem here.

We’ve already gone through a handful of new bushings, and something will have to be done differently when we go pressing the new ones in.

But we did get something accomplished! We removed the steering rack. Not only to open up more access for the welding, but we have new bushings for it too that will need to be pressed in. My brother has new inner & outer tie-rods ready to go be installed, so we didn’t even bother trying to separate the rusty old tie-rods. We just cut off the outers, and used this handy removal tool to do the inners.

But the tool didn’t quite fit, so I had to make some modifications.

Even though the flats were the right size, the rest of the “crow’s foot” wasn’t quite big enough to fit around the round part of the inner tie-rod. I tried removing a little material at a time, but it was going too slow.

!!! UNKNOWN CONTENT TYPE !!!

So I measured the outer diamater of the tie-rod, and the inner & outer diameters of the crow’s foot, and found that the 10mm portion was going to have to be shaved down to 7.5mm. It just isn’t going to fit otherwise.

To do this, I decided to make another special tool. I grabbed some wood scrap and threw together this little stand to zip-tie my Dremel to. It’s sort of a -oh, what are they called?- a router table? No, I think maybe the word is linisher ? Something like that, I guess. You get the idea.

Anyway, this platform allowed me to remove much more consistent amounts of material from the crow’s foot. I was able to remove just enough to make it fit, retaining as much material as I possibly could. The inner tie-rod remover tool now worked like a charm, and after disconnecting some hydraulic lines and fighting with the rusty pinion splines, we finally got the rack out.

Next, I’m pretty sure the stabilizer bar will have to be replaced. Not on account of rust, but my dumb ass got a little too sloppy with the cutoff wheel. I accidentally knicked the bar instead of the tie-rod that I was supposed to be cutting. Now there’s a 3mm-deep gash in the otherwise 18mm thick stab-bar. If only I had been more careful. Or known in advance how difficult it would be to track a replacement down...

DISCUSSION (20)

crowmolly > Urambo Tauro
09/04/2018 at 12:34

Maybe something as simple as dish soap can help with the bushing situation.

Urambo Tauro > crowmolly
09/04/2018 at 12:39

I hope so. Turns out, that’s what the shop manual recommends using. Maybe I wouldn’t have tried the silicone if I had read that first. I’d feel better if there was a way to pre-compress the bushing before sliding it in, though. S omething like a piston spring compressor, but smaller.

JustAnotherG6 > Urambo Tauro
09/04/2018 at 12:42

Freez e the bushing and heat the housing?

crowmolly > Urambo Tauro
09/04/2018 at 12:44

Might be way off base, but can you use a bolt, nut, and a pair of large washers to make a pre-assembly? Then adjust the compression and press on the bolt head.

Urambo Tauro > crowmolly
09/04/2018 at 12:51

I’m talking about maybe somehow compressing the outer diameter of the bushing so that the whole lip goes in at once while pressing.

The bolt-nut-washer trick is an excellent solution for those without access to a press, though!

crowmolly > Urambo Tauro
09/04/2018 at 12:53

Ah, I got ya.

Did you try throwing the new ones in the freezer overnight?

Urambo Tauro > JustAnotherG6
09/04/2018 at 12:54

I like where your head’s at in terms of expansion & contraction. But wouldn’t freezing the rubber make it less pliable?

Urambo Tauro > crowmolly
09/04/2018 at 12:55

No, I fear that it would just make the rubber even more likely to tear, even if it did shrink a little.

crowmolly > Urambo Tauro
09/04/2018 at 12:58

FWIW I’ve done it many times without issue. Just have to have it in the freezer for a while.

JustAnotherG6 > Urambo Tauro
09/04/2018 at 13:02

It wouldn’t stay frozen....

When you go to insert it, it may be less likely to get hung up on one side since it is (hopefully) a bit smaller in diameter and a bit harder (less pliable) making it easier to insert. *your mileage may vary

This is what they do when inserting tight tolerance bushings.

Urambo Tauro > JustAnotherG6
09/04/2018 at 13:10

Well yeah, of course it hav e a permanent effect on t he b ushi ng. I’m just concerned that reduced pliability might make it even more likely to tear away from t he inner sleeve that it’s bonded to, and less likely to squeeze into the tube . Freezing it might shrink it a little, but it won’t make the outer diameter of the bushing smaller than the inner diameter of the tube. T he rubber’s still going to have to compress.

!!!error: Indecipherable SUB-paragraph formatting!!!

Urambo Tauro > crowmolly
09/04/2018 at 13:12

Well if that is indeed the preferred method for this type of bushing, I’m willing to give it a shot. I’m just nervous about destroying another bushing, is all .

JustAnotherG6 > Urambo Tauro
09/04/2018 at 13:14

How close is it? OD of bushing vs. ID of tube?

crowmolly > Urambo Tauro
09/04/2018 at 13:15

Freeze it, soap it, and send it. LOL

Urambo Tauro > JustAnotherG6
09/04/2018 at 13:31

The bushing has an OD of about 30mm in the middle, but the flange end is about 34mm. The tube that it must go into has an opening of 29mm, which narrows down to 27mm in the middle.

The old bushings that came out have almost the same dimensions (taking into account some permanent deformation from age and use). And the part numbers match. I’m 99% sure that we have the correct bushings.

merged-5876237249235911857-hrw8uc > Urambo Tauro
09/04/2018 at 13:52

If you can press the outer edge of the bushing while you’re pressing in the center sleeve, it should go without separating the sleeve. So the bolt and washer on the press may work for you as well.

How about an exhaust coupler that you could wrap around the bushing to squeeze it down to the 29mm dimension? Or press it through something that has a taper to get you from the larger bushing size to the arm opening dimension. Or take a copper pipe coupling and cut one side and use that to wrap the bushing and squish it down, then press it in.

JustAnotherG6 > Urambo Tauro
09/04/2018 at 15:06

E w. I don’t doubt you have the correct bushings, i t just sounds like such a pain to make it work.

Urambo Tauro > merged-5876237249235911857-hrw8uc
09/04/2018 at 15:32

I did try something similar to that, the top cut from a plastic P owerade bottle. It ramps down to a ID of about 30mm, which shou ld squeeze the flange of the bushing enough to slide into the tube (which has a short initial “ramp” to 29mm before it gradually narrows down to 27mm). It got stuck, or maybe I wast just frustrated and gave up too soon. Maybe I should give it another chance.

Urambo Tauro > JustAnotherG6
09/04/2018 at 15:32

Toit like a toiger!

Future Heap Owner > Urambo Tauro
09/05/2018 at 04:15

Sweet drill stand cum sanding station