Rocker arm bushing source
 

Anyone have a source for 911 rocker arm bushings( bearings)?

I was looking for the same, this is what I found and posted on Gruppe B

http://www.gruppeb.org/forum/viewtopic.php?t=4629

Ordered some the other day. Since we have an account with Motion Industries, they cost less than a buck each. I'll post my findings on them when they arrive. Also spoke with Walt at Competition Engineering and he confirmed that there are no sources for the original Porsche bushings.....but Porsche will sell you new rockers for $100 each! Doooh!

Porsche must not like you, Pelican will sell you a new rocker arm for 62.75..... :)

Cheers

I got bushing material from a bearing house and then we cut the OD for the press fit and ID to be ready for the honing of the fit to the rocker shaft... I forget just now the exact bronze part number. I think bronze basically comes in 3 types.. soft, med. and very hard.. We used the med.
Don't forget to drill and debur the oil holes

bronze bushing material is waaaaayyyyy too soft. lots of pressure exerted on rocker bushings. Got the Buntings today and just finished doing a set of rockers. They are perfect.

would be interesting to see if the "experts" weigh in on this.. re. "building" your own bushings from various materials... until now haven't heard of Buntings. The machine shop I used has been doing 911 heads (that's about all he does) for decades and I used what he recommended. I would not be surprised if the bronze was not the best choice.... how did you arrive at using Buntings?

I read the Buntings website info. I remember now the bushings I got were 660. There is a bunch of interesting info... re. press fit, running clearance, groove types, graphiting.. Not sure if the clearance recommendations follow the Porsche numbers... and I don't remember what I reemed to but when I was done I could only feel a very slight play... continued conversations re. press fit, clearance, grooves etc. would be interesting.

Description: 18 MM ID, 20 MM OD, 25 MM LENGTH, TEFLON LINED, SLEEVE BUSHING
MFG Part #: M1825BU BRG
Manufacturer: BUNTING BEARINGS

this is from the cgarr above... sounds pretty good.. I guess these get reemed to size or is the tolerance of the running clearance going to fall within what is needed when using "buffed" rocker shafts. I think my rocker shafts were buffed on some sort of centerless machine... not sure how much is/was taken off but it is not much

This was a perfect press fit, ran a ball hone thru the bushing for a perfect fit. Remember to keep the split side to the top and it always helps to use a wood dowel in the rocker when drilling the oil holes.

[IMG]http://i30.photobucket.com/albums/c3...1/rocker-1.jpg[/IMG]

good idea re. wood dowel... I can't remember what we did on that. I did go in and "round" out where the oil hole is to give some room for oil to accumulate
you say split to the top... :confused:
are you refering to the original style where there is a complete split in the bushing? The bushings I made of 660 were solid all the way around..

Thin bushings of the sort are typically rolled bushings, with the split. If you machined a slighjtly heavier piece of cast bronze bushing, that's fine too. It's what most of the shops do, if you were to send them out. The difference will only be the process used to make the bushing.

oh ok, I didn't know the rolled type were available in any way... yes I machined pieces of cast bronze 660. I'm pretty sure there is a more ultimate way to do it than I did.. we'll see how long they last. I like the sound of the teflon lined or other such exotica and I guess if grooves are put in in the proper type and pattern that could help also. So far so good with what I did. If you have a shop do this for you.... remember to check the tolerance. I guess at this point we now all know to check what the shops do... no dig intended to the real good shops.

Trying to simulate these new bushings installed on an engine. Adding some load, some heat while spinning in the lathe and very little oil to see how they hold up. This may be one of those things I leave on all night and check it in the morning. Should have a test engine for these soon. So far after several hours no change in the bushing.

http://i30.photobucket.com/albums/c3...rockertest.jpg

Craig,
very admirable but not sure if this matches the real situation enough to prove too much...
what bushings are on the lathe seup? 660 bronze?

I am testing the TEFLON LINED, SLEEVE BUSHING, I realize there is no shock factor with this type of testing, but I had to try something before they go in the engine. I was concerned with the teflon not holding up. The teflon is a very thin lining over the bronze, even if the teflon was removed the clearance is not excessive.

For what its worth, I setup a stock rocker (bronze bushing) in the lathe and could only run it for 5 minutes at which time it was too hot to handle, the teflon lined bushing is still running and hardly warm.. But the true test will be in the engine.

well that sounds pretty good... the teflon film seems to be hanging in there for whatever reasons.. certainly worth a try to put in an engine... I applaud the experimental effort you put in. I find in almost all experiments even if they are not perfect.. are helpful

I needed the worst case test and something to compare to so this is what I did next to try and make both fail.

No oil test. Stock bushing after brake clean, ran 7 min then started to seize up, this baby was hot, bushing was scared badly, shaft did not look good.

Next was the teflon lined after brake clean, Well after 20 min and still not hot I added some Mapp Gas heat up to 500 degrees to help get it to fail, but it didn't, its still running and cooled back down and this is with out any oil.

But again, the only real test that counts is time in the engine.

Just found this regarding these bushings and the material used: Read towards the bottom:

Little Resistance With KS Bearings Permaglide(R)

DETROIT, April 12 /PRNewswire/ -- Kolbenschmidt Pierburg's KS Bearings
division is expanding the use of its slippery Permaglide(R) friction-reducing
material to produce components that take up less space, weigh less and offer
improved performance for North American automotive products.
After succeeding in its quest to find an environmentally friendly material
to replace the lead found in many automotive lubricants, KS Bearings now uses
Permaglide(R) on components such as transmission gear-shift-lever guides, door
hinges and shock absorbers.
"This really is a break-through material that can be incorporated into
hundreds of different automotive applications," notes Mike Adrian, KS Bearings
vice president of North American sales. "Permaglide(R) offers advantages not
only in cost, but in weight and performance as well. Its use also will have a
positive environmental impact."
The patented Permaglide(R) process, developed and owned by Kolbenschmidt
Pierburg, incorporates a 1-millimeter to 1.5-millimeter sandwich of PTFE
(polytetrafluoroethylene, commonly known as Teflon(R)), zinc sulfide and
bronze bonded to a steel backing.
Components with an extremely slippery P1 Permaglide(R) surface can handle
higher loads, speeds and temperatures. P1 Permaglide(R) can be manufactured
to require no lubrication, allowing manufacturers to eliminate many lead-
containing lubricants such as the grease used on conventional front-wheel
drive shafts. Permaglide(R) components satisfy the ELV (end-of-vehicle-life)
directives already in place in Europe that require vehicles to be 85 percent
recyclable by 2006.
KS Bearings also produces a machinable version of the material, P2
Permaglide(R), for components that may require lubricants because of load,
temperature or speed. The frictional characteristics of Permaglide(R)
materials can be custom-tailored to a specific application. "If it's too
slippery -- for example, on a door hinge -- we can add more resistance to give
a better feel," Adrian says.
Permaglide(R) is finding its way into areas that previously were
considered unsuitable for this type of application -- inside an internal
combustion engine, for example. "We're currently testing Permaglide(R) on the
rocker arms and camshaft of a high-performance V-8 engine for a major
manufacturer," Adrian says. Permaglide(R) reduces parasitic friction losses
on those components, improving the overall efficiency of the engine.
"We've also have had strong customer interest in our door hinges and shock
absorbers," he says, "and we have the manufacturing capability to meet our
customers' needs for multiple shapes and sizes and any geometry."
KS Bearings engineers can redesign components to take up less space with
lower weight and improved performance. The division uses Permaglide(R) on 100
percent of the door hinges, pedal systems and windshield-wiper components it
manufactures for a major German automaker.
Typical areas of application for Permaglide(R) components include:

Auxiliary systems -- common-rail pump, brake and fuel systems, engine belt
tensioners and starters.
Powertrains -- contoured switching guides and dual-mass flywheels.
Suspension components -- shock absorbers, struts, steering systems and
brake systems.
Chassis -- hinges on doors, hoods, trunks and tailgates, windshield
wipers, body systems, seat adjustment gear, safety belt pretensioners and
pedal systems.

Permaglide(R) also is used in many non-automotive commercial and
industrial applications. Kolbenschmidt Pierburg AG owns worldwide rights to
the material, and the company markets the process to non-automotive customers
through a license with INA-Schaeffler KG of Germany.
KS Bearings, a key manufacturer of engine bearings, journal bearings,
bushings, flanged bushings and thrust washers for the global auto industry, is
a division of Kolbenschmidt Pierburg, a leading supplier of bearings, pistons,
automotive oil and water pumps, throttle bodies, secondary air systems and
exhaust flaps, as well as electric exhaust-gas-recirculation systems and
aluminum engine blocks. Kolbenschmidt Pierburg has North American production
plants in Fountain Inn, S.C.; Greensburg, Ind.; Fort Wayne, Ind.; Marinette,
Wis., and Leamington, Ontario, and a North American sales office in
Southfield, Mich.
Kolbenschmidt Pierburg AG is a subsidiary of Rheinmetall AG. The company
has approximately 11,400 employees at its five automotive divisions. Global
sales for its Aluminum Technology, Pierburg, KS Pistons, KS Plain Bearings and
Motor Service divisions totaled nearly $2.4 billion in 2004. Additional
information is available on the Internet at

Nice work Craig!

cgarr,
is Buntings just sourcing from Kolbenschmidt or is this a whole new teflon development by Buntings? I don't know how big Buntings is but the KolS efforts are probably not for shallow pockets. This could be the be all end all for rocker bushings.

Buntings may be a knock off of the KS and I would guess thats the case at only 90 cents each, the KS list at $4.00 each which is still cheap, cheap, cheap... and that list, thats not what we pay..

amazing info craig! My head is spinning, no pun intended, of all the applications inside an engine this could be used... maybe an engine with minimal oil for maintaining some specific tolerances inside the engine... but basically the oil is the medium to carry away the sm metal pcs to the filtration sys and not using oil in its traditional role(s) of: lubrication; heat mgt; remover of metal particles.
Way cool! I have to read up on this. Do you know if this can be "applied" to existing parts or only for new mfgrd parts?
Bob

Just talked to the Rep at Motion Ind. and Bunting, Garlock and KS (Permaglide(R) are all the same material, just a big price difference. They have thousands in stock!

You can go into http://www.applied.com and look up the specs on all sorts of bushings. This is the spec for the Garlock bushing:

# Steel backing gives DU its exceptionally high load carrying capacity; thin, compact design; excellent heat dissipation; and dimensional and structural rigidity.
# Porous bronze innerstructure: This comprises a nominal 0.010 inch (0.25 mm) thick layer of carefully sized bearing quality bronze powder which is sintered onto the steel backing. This porous structure is impregnated with a homogeneous mixture of PTFE (polytetrafluoroethylene) and lead. In addition to providing maximum thermal conductivity away from the bearing surface, this unique bronze innerstructure also serves as a reservoir for the PTFE-lead mixture.
# PTFE-lead overlay: This low friction overlay, approximately 0.001 inch (0.025 mm) thick, provides an excellent initial transfer film which effectively coats the mating surface of the bearing assembly, forming an oxide type solid lubricant film. As this film is depleted, the relative motion of the mating surface continues to draw material from the porous bronze layer. When conditions are severe, the feed of lubrication is increased. The peaks of porous bronze coming in contact with the mating surface generate localized heat and, due to the high thermal expansion rate of the PTFE, force additional lubricant to the bearing surface. The relative motion of the mating parts wipes the lubricant over the interface, continuously restoring the low friction surface film.
# Loads - P: dynamic pressures up to 20,000 psi (140 N/mm2) assuring high load carrying capacity and excellent resistance to shock loading
# Speeds - V: Speeds up to 1000 fpm (5m/s) without lubrication; 2000 fpm (10 m/s) with lubrication
# PVs to 50,000 psi-fpm (1.75 N/mm² x m/s) for continuous operation, 100,000 psi-fpm (3.50 N/mm² x m/s) for short-term use. In actual operation, DU bearings have been successfully used at levels which approach 3,000,000 psi-fpm (105 N/mm² x m/s) lubricated.
# Temperatures from -328 °F to 536 °F (-200 °C to 280 °C) making it suitable for use in applications well beyond the scope of most liquid lubricants
# Ideal for all types of rotating, oscillating, sliding motion, and both radial and thrust loading
# Can be used totally dry, fully lubricated, or with intermittent lubrication and can be used in the presence of many industrial liquids

See this is quite interesting. I wondered how the teflon stood up to your MAPP gas/lathe test there as PTFE really starts to deform and rapidly expand under heat but that paragraph really explains the impregnated coating and how they're using the PTFE's thermal expansion rate to a great advantage. It's sort of like a miniature Accusump for the rocker shafts :)

As far as the coating deformation under the load of the spring tension while installed in the motor, virgin PTFE has a ~20% deformation percentage rate measured at 1500psi at 200F. Being that these have a compound, I'd imagine that deformation rate to be even greater(and coupled with the bushing material itself). I think they're going to hold up great :)

Pretty neat stuff here.

can someone make up a few bushings and throw them in a car and see what happens? Can the Permaglide bushing take honing to fit? What is the recommended clearance against the shaft?

Awesome! I rebushed my rockers for $35.00... can't beat that.

A drill, dremel, bench vise, a 14 & 17mm socket, and a 3/4" copper coupling were all the 'professional tools' it took to press the bushings in & out. Drilled oil holes after pressing in the bushing, flared the hole slightly with a dremel - took <10 minutes per arm. They didn't even need any honing to fit.

Thanks Craig! If you plan on attending an RSR/PCA Grattan event, send me an email with your beer preference ...

Excellent, I'm going to mention this to a buddy. We are pulling his 3.2->3.4L engine out soon. No honing to fit, that is great.

Craig's had these running in some engines subject to some fairly good abuse. I'll let him share what engines they're running in.

Isnt this part of every rebuild he does for people? If so, probably alot of these in engines since he is the go to guy for Rocker rebuild. he did mine.

I put these in during my last rebuild. the after market rocker shafts wore pretty badly. I replaced them with genuine porsche rocker shafts and they have been doing fine ever since. I have about 20k on the rebuild. Next year when i pull it apart again for the efi swap I'll post some pictures and an update.

How are these holding up?

Are these killing the rocker shafts once the coating wears?

No signs of problems in any of the engines i've been around. When installed properly (sized to fit rocker arm bore & squared-up) they have proven to work great.

Just ordered from Motion Industries - Keeping Industry in Motion

Item 37124

Mine did not hold up well. Toast at 13K miles.

Sorry for the late reply.

I would suggest honing them lightly with a grape hone and cutting an oil channel to help with lubrication, 2 things I did not do.

Re: Rocker arm bushing source
 

Tell me about this oil channel. Honing the Teflon surface would cause damage / premature wear I would think.

If you look at your rocker shafts, there is a wear spot. It's on the inboard side. So I would cut a shallow channel from the top oil hole along the inboard side, maybe 1/2 of the way to the bottom hole, to help guide oil in that direction. The intakes and exhausts get the channel located in a different spot according to this theory, since a different hole ends up on top. Wether or not oil gets anywhere by gravity with the engine running is of course debatable...

The DU bushings are a pretty exact fit on the rocker shafts. The DU material expands as it gets hot. So I can see the bushing basically sealing and keeping the oil from getting to the wear spot. Very lightly honing with a grape hone will scratch the DU coating and create a bit of more clearance, but should not remove it completely. The scratches should help it move oil. My rocker shafts had very visible metal transfer from the DU bushing, indicating a lack of lubrication. This is, again, just a theory, and could be complete balderdash.

My engine has other unexplained issues with insane valve guide wear (a local shop is totally baffled as well, so it's not just that I am a clueless moron with left handed retarded monkey disease), so there may be other issues with my engine. One theory is that I, my engine, my car, or all of the above, are cursed ..

Others have gotten these bushings to work, so it must be possible.

Re: Rocker arm bushing source
 

If the issue is thermal expansion effectively sealing the bearing surface from oil then a trim where the bearing roll closes would allow expansion to prevent binding. I'm not an engineer though so I don't have expansion rates for the two materials handy to compare. The other alternative if they're too tight would be to open the bore within the rocker.



-Andrew