Poly-graphite Bushings
03-26-2002 | 01:01 AM
#1
Thread Starter
Rennlist Member
Joined: Nov 2001
Posts: 130
Likes: 5
From: Naples, NY
Poly-graphite Bushings
I've been re-doing my suspension (T-bars, shocks, bearings, ball joints, bushings) and opted for poly-graphite bushings for the rear spring plates. Two observations, the bushings need a 'lot' of sanding/grinding to fit onto the spring plates, and they are somewhat out of round. I'm taking 30-40 thousandths off the inner diameter, and perhaps a bit less on the OD. Is this typical? I've devised a couple of 'tools' to do this and still keep the bushing round and parallel, but it is a painfully long process. It was recommended to size the bushings to get a slight or 'magnetic' drag on the spring plates and spring plate covers when installing, but I'm wondering if one side should not be tight (and locked in place) with the other side having the drag fit, allowing rotation with the suspension movement. At this point I'm considering switching to Neatrix, but have net pulled the trigger yet. Do the Neatrix bushings require sanding as well? I understand Neatrix may be glued to the spring plate and lubed on the OD, is this the case or are they also drag-fit on both surfaces? Any thoughts on the fit and sizing process for either type is appreciated. Spring is getting here fast.....
03-26-2002 | 03:00 AM
#2
Race Car
Joined: Jun 2001
Posts: 3,706
Likes: 9
From: Virginia Beach, Va.
Herb, you're dealing with a subject that has many facets. I have heard opinions that range from a snug fit, both surfaces, to being glued on the outer surface and so on.
On my SC, I would up going to Neatrix...because I heard that installing the Weltmeister poly-graphites came with a high PITA factor.
Call Jason at Paragon-Products, he seems fairly knowledgable in regards to this subject. Also, I'm sure a another poster will "chime in" on the subject.
I do know one thing, you need to clean the sh#$ out of the bushing area of the trailing arm to fit anything in there! My Neatrix bushings came with a sharp, rigid/rounded putty knife of sort to facilitate removal of the old bushing and what remains once you get the main part of it out.
Good luck on your endeavors!
On my SC, I would up going to Neatrix...because I heard that installing the Weltmeister poly-graphites came with a high PITA factor.
Call Jason at Paragon-Products, he seems fairly knowledgable in regards to this subject. Also, I'm sure a another poster will "chime in" on the subject.
I do know one thing, you need to clean the sh#$ out of the bushing area of the trailing arm to fit anything in there! My Neatrix bushings came with a sharp, rigid/rounded putty knife of sort to facilitate removal of the old bushing and what remains once you get the main part of it out.
Good luck on your endeavors!
03-27-2002 | 09:05 AM
#3
Thread Starter
Rennlist Member
Joined: Nov 2001
Posts: 130
Likes: 5
From: Naples, NY
Jeff- Thanks for the reply. Did you end up glueing your Neatrix bushings on either side? For now Couple days) I'm sticking with the poly- bushings.... sanding my way to custom fitment. What I wouldnt goive for a small althe right now. I like the ideas I ve seen on adding a zirk fitting and a groove in the bushing, at least for the fronts. If anyone out there has had success with the groove, let me know how you placed it. I'm guessing adding a groove along the length of the bushing would give the most lubrication but I also worry that the groove becomes a wear point. One or more circular grooves around the inner diameter would not compromise the wear, but also wouldnt propagate the grease nearly as well. As far a sanding/grinding the ID of the rear bushings, has anyone found an appropriately sized 'stripping bit'...drill insert with overlapping flaps of sandpaper attached which raise under the centrifugal force to apply pressure? I'm using a modified cylinder hone with coarse, adhesive backed-sandpaper strips attached to the honing stones. It works and keeps the centricity correct, but the process is slow. Comments appreciated.
03-28-2002 | 09:22 PM
#5
RL Technical Advisor
Joined: May 2001
Posts: 11,871
Likes: 66
From: Portland Oregon
Herb:
These Weltmeister polyurethane bushings are cast, not machined, and as such vary quite a bit.
We've installed them in many cars since 1978 and I've always trued them in our lathe and then machined the ID's to fit. Its very time-consuming and does take some experience to make them fit properly without binding or squeaking.
Adding zerk fittings and grease channels to the ID of the bushings cannot hurt. I use that teflon based grease on those things.
These Weltmeister polyurethane bushings are cast, not machined, and as such vary quite a bit.
We've installed them in many cars since 1978 and I've always trued them in our lathe and then machined the ID's to fit. Its very time-consuming and does take some experience to make them fit properly without binding or squeaking.
Adding zerk fittings and grease channels to the ID of the bushings cannot hurt. I use that teflon based grease on those things.
03-29-2002 | 02:38 AM
#6
Racer
Joined: May 2001
Posts: 382
Likes: 0
From: Monroe, La
Poly-graphite bushings are a bit on the hard to fit side, they do require a little creative engineering to get right.The Netrix do not need to be glued,they fit very well. I do not understand the need to glue them... and that "tool" they send is totally useless !
Netrix bushings are great for both track and street, the polys are mostly for the track, hard and squeeky,unless ocasionally lubed.
Netrix bushings are great for both track and street, the polys are mostly for the track, hard and squeeky,unless ocasionally lubed.
03-30-2002 | 05:50 PM
#7
Thread Starter
Rennlist Member
Joined: Nov 2001
Posts: 130
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From: Naples, NY
Steve, Chuck, Mike-
Thanks for info. I'm 'deep' into these poly- bushings and I think I'm gonna stick with them. Steve, your comments of using a lathe have me drooling. I had access to one as a kid (Dad's machine shop) and really miss having one now. I gotta look for a used, small one, but thats another story. I've found my front bushings are very close, out of the box. They need a little sanding on the ID and the OD is snug. I plan to keep the OD tight and add zirks as Steve mentioned. I figure a couple channels around the inner circumference should help as well...Steve have you also added a channel along the length, not quite extending to the ends? The rear bushings continue to plague nme but I'm getting there. I found a 3" diameter 'flap' sanding bit that I'm cutting down to fit into the ID. I've got two bushings done and hope this bit speeds up the ID machining process. Steve- have you added zirks to the rears with success, and do you keep the OD snug (or even locked with the zirk fittings) and rely on the ID to to be the pivot point? Thx for the continued input.
Thanks for info. I'm 'deep' into these poly- bushings and I think I'm gonna stick with them. Steve, your comments of using a lathe have me drooling. I had access to one as a kid (Dad's machine shop) and really miss having one now. I gotta look for a used, small one, but thats another story. I've found my front bushings are very close, out of the box. They need a little sanding on the ID and the OD is snug. I plan to keep the OD tight and add zirks as Steve mentioned. I figure a couple channels around the inner circumference should help as well...Steve have you also added a channel along the length, not quite extending to the ends? The rear bushings continue to plague nme but I'm getting there. I found a 3" diameter 'flap' sanding bit that I'm cutting down to fit into the ID. I've got two bushings done and hope this bit speeds up the ID machining process. Steve- have you added zirks to the rears with success, and do you keep the OD snug (or even locked with the zirk fittings) and rely on the ID to to be the pivot point? Thx for the continued input.
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03-31-2002 | 11:29 PM
#8
5th Gear
Joined: Feb 2002
Posts: 5
Likes: 0
From: sf
I'm having the same problems with my front suspension Poly bushing. I installed them over a year ago and they've started squeaking. I wish I had installed the Zert fitting from the beginning. My question, is it possible to install the Zert fitting while the control arm is still on the car?
Rick
Rick
04-02-2002 | 01:05 AM
#9
Thread Starter
Rennlist Member
Joined: Nov 2001
Posts: 130
Likes: 5
From: Naples, NY
Rick-
Adding Zirk fittings after the fact is a tough one I think. I'd be worried about drilling into the A-arm. I suppose your could drill through the housing and bushing part way. Then use a flat end bit to drill the balance of the way through the bushing itself to reach the A-arm. Have to be careful though, and clean out any metallic shavings. I think I might tend to live with the squeak until I was motivated to drop the A-arms again. I'm installing my fittings as we speak in mine. Can you tell me how tight you left your bushings, on both ID and OD? I'm considering leaving the bushing ID slightly tight at maybe .004-.005" undersize (fair amount of reistance to rotation by hand), while leaving the OD for the bushing housings large and tighter, forcing the rotation on the ID.
Adding Zirk fittings after the fact is a tough one I think. I'd be worried about drilling into the A-arm. I suppose your could drill through the housing and bushing part way. Then use a flat end bit to drill the balance of the way through the bushing itself to reach the A-arm. Have to be careful though, and clean out any metallic shavings. I think I might tend to live with the squeak until I was motivated to drop the A-arms again. I'm installing my fittings as we speak in mine. Can you tell me how tight you left your bushings, on both ID and OD? I'm considering leaving the bushing ID slightly tight at maybe .004-.005" undersize (fair amount of reistance to rotation by hand), while leaving the OD for the bushing housings large and tighter, forcing the rotation on the ID.
04-02-2002 | 03:52 AM
#10
RL Technical Advisor
Joined: May 2001
Posts: 11,871
Likes: 66
From: Portland Oregon
Hi Herb:
A coupla more notes about these polyurethane bushings,......
1) Truing the Bushings: Although I know very well how inconvenient it is to find a lathe, IMHO this is the foundation for enjoying squeak-free thermoplastic suspension bushings. These things simply are not always round or concentric. Plus, the inconsistent OD and ID makes proper fitment a crapshoot unless you perform this important step. The OD should be a firm hand-fit and the metal suspension parts, (A-arm or spring plate) should rotate with very slight drag in the ID if you do not wish to have any binding or squeaking. Its a finesse thing, I'm afraid.
2) Zerk Fittings: The suspension parts must be modified and prepared beforehand for these to work correctly. The A-arms and bushings must be drilled for grease passages and the ID of the bushing must be grooved with a grease channel so it can flow between the OD of the suspension part and the ID of the bushing. The drilled hole will permit you to anchor the Zerk fitting, too.
Practically speaking, one can install effective Zerks into all 4 front suspension pivots to permit one to lubricate the bushings but in the rear, only the outer spring plate ones. Those inner spring plate bushings requires one to be very creative,......
Hope this helps,......
A coupla more notes about these polyurethane bushings,......
1) Truing the Bushings: Although I know very well how inconvenient it is to find a lathe, IMHO this is the foundation for enjoying squeak-free thermoplastic suspension bushings. These things simply are not always round or concentric. Plus, the inconsistent OD and ID makes proper fitment a crapshoot unless you perform this important step. The OD should be a firm hand-fit and the metal suspension parts, (A-arm or spring plate) should rotate with very slight drag in the ID if you do not wish to have any binding or squeaking. Its a finesse thing, I'm afraid.
2) Zerk Fittings: The suspension parts must be modified and prepared beforehand for these to work correctly. The A-arms and bushings must be drilled for grease passages and the ID of the bushing must be grooved with a grease channel so it can flow between the OD of the suspension part and the ID of the bushing. The drilled hole will permit you to anchor the Zerk fitting, too.
Practically speaking, one can install effective Zerks into all 4 front suspension pivots to permit one to lubricate the bushings but in the rear, only the outer spring plate ones. Those inner spring plate bushings requires one to be very creative,......
Hope this helps,......
