Springplate bushing replacement help: a few questions
 

Hi all,

I checked extensively on the archives on this, but couldn't find a specifc answer. I am replacing the dead/deformed OE rubber with PolyGraphite bushings (it's a track-only car) and had just cleaned up the sprinplate bushing area with a wirebrush. Well the PG bushings fit onto the springplate shafts perfectly ...minimal hand pressure and on they go, and can pull off fairly easily as well. I'll have to custom fit the bushing for the OD into the car, but it looks like it won't take much. Well here are my questions:

1. Should I grease in the ID of the bushings as well as the OD? I realize the OEs were vulcanized onto the shaft and others like Neatrix get glued in, but I don't see why they have to move along with the springplate, fused together.

2. As I hand-fit the bushing for the OD, I presume I should get a very easy vertical movement of the arm, right?

3. As for the outer bushing that the springplate cover bolts over, do I have to custom fit that OD as well, even if the bushing moves freely on its ID as I had mentioned?

I'd appreciate help on this. Thanks a bunch!

Edward

I did not modify my poly bushing when I put them in. The OD is snug and will take some effort to push them on. In fact, I used the 4 studs that hold on the spring plate to slowly press them in once I got the bushing far enough for the nuts to grab. I believe I used a 1" diameter wood dowel to tap it on.......along with a fairly BFH.

I used lots of poly grease - everywhere. Didn't want the damn things to squeak. Got about 6,000 kms on in 2005 - so far OK.

As for movement, never played with this because the new torsion bars went in at the same time.

Have fun.

Don't cut them. Just use silicon grease, such as Dow Corning 111 or 112. They won't squeak, and the silicon grease will make installation easier.

Hi Ed. Sorry I haven't been online much these days...

You don't want them too snug. The inside or outside bushings. You won't know until you put it all together on the car. The cover and the car will compress the bushing a little, then you can decide if it's too snug. If you have to gorrila arm the springplate up and down, they are too tight. You can sand the bushings down a bit with a belt sander making sure to take material off the OD evenly. The chasis and the cover are nto perfectly round so it's OK to use the sander. You don't want to take too much off! So DON'T TAKE TOO MUCH OFF.

Jim's suggestion og grease is good.

Thanks, all ...I appreciate the help!

Souk, thanks for getting the bushings to me!

So I gather that the SOP is grease 'em up good and I'm done (I'll check for stiction on the arm w/o torsionbar, of course). This implies, then, that in answer to my 1st question, there is no real "need" for the bushing to be fused to the arm ...thought so. I would "think" that free movement at the ID as well as the OD of the bushings would be a good thing, so be it. And I'm using Mobil1 synthetic grease ...supposed to be better than a petroleum-based grease which degrades plastic, as I remember reading. Again, thanks for the all the insight, guys!! :)

Edward

Edward,
Do a search using Chuck Moreland's name. He posted a great thread a long time ago regarding installing polygraphite bushings along with adding grease zerks to lubricate them. I believe he posted this before he started making his current polybronze bearings. Many people have complained about them squeeking after they have been in there for a while.

Marv:

Very correct...however, we're talking about the rear of the car here....no way to re-grease these guys after the install...most certainly not the inner ones.... no way to get a zirk fiting for these....

Chuck's excellent article shows the front, where a zirk fitting is possible for all pivoting locations.

As to the bonding question...this has been open to much debate. OEM has these fused, and the twisting of the rubber contributes to the overall spring rate the car sees. When free to rotate, these don't contribute to the spring rate ( just an observation...don't think this aspect is important). However, rubber or plastic makes a terrible bearing surface against metal when free to rotate. For this reason, some say it is not good to let the spring plate pilot tube rotate relative the ID of the bushing, and therefore should be bonded, like the factory did. An original smearing of grease will only go so far....

So the debate continues....

Wil

There is no question that the OD of the poly bushings should not be bonded. The poly bushings will never behave like the rubber bushings that came from the factory. The rubbers were intended to flex. Their effect on spring rate is rather unscientific (existant, but not something I count on), esp. after 20+ years of service. A majority of us who change bushings are changing the torsion bar size at the same time, so it's a whole new ball game.

As for polygraphite bushings making good or bad bushings compared to others available....show me a bushing that will retain grease on the contact service, even with a grease zirk.

I would not use the Mobil 1 syn grease. Use the silicon grease specifically made for the suspension bushings as suggested. Mobil 1 is for grease gun and pressed metal-metal fittings and is probably hydroscopic.
IMHO
Bill K

Souk:

I don't understand your counter-points....

- I ( others ?) never mentioned OD in the context of bonding the bushing...only the ID.
- I simply stated that when NOT bonded, the shaft will turn in relation to the ID of the bushing.....altogether not a good thing as no plastic or rubber is made for that kind of service, although we seem to do it here.

To bkreigsr...correct on the advice to use specific-purpose grease, but I don't think your comments on Mobil 1 syn is correct...being synthetic I don't think it would absorb water ..if that's what you meant ( in which case it would be termed "hygroscopic")...

Wil

Ahh... I was thinking of a too many things at the same time Wil. Made my post vague as usual. But your post about how "some say it is not good to let the spring plate pilot tube rotate relative the ID of the bushing, and therefore should be bonded, like the factory did" made my mind click.


The point I wanted to make is that the polygraphite bushings do not need to (should not) be bonded on the ID or OD. The plastic bushings are not idea, but there are no perfect solutions out there yet. So I for one prefer them for the cost of $48 bucks or so.

Thanks for all the input, guys ...this is helpful.

OK, so I'm not concerning myself with bonding the ID of the bushing ...that makes things that much easier.

As for grease, I figured a synthetic would be fine, and Mobil1 being what it is, a good choice. Is there a better alternative that is readily available at, say a NAPA store?

Edward

as for the grease, synthetics can absorb anywhere from 0-8% moisture over time, and since this is not the kind of job you want to do very often, get the best, even if means mail order
try our host, pn for 1 oz = PEL-SUSGRS1
Bill K

I like the Neatrix bushing. And I agree that no glue should be used. I am absolutely convinced that the best grease by far is the silicon grease, for this application. And I suspect no modifications to the bushing are necessary. The forces that act on suspension parts are colossal. So, it is not necessary for them to be smooth like a door hinge. It is more important for them to be so darned snug that there is no improper movement (slop). So, some say the tighter the better. I'm not sure that's wrong. I'd be tempted to mash them in there and let the road forces beat them into submission. The silicon grease will guarantee smooth movement.

IMHO.