Machining & Materials for Lifter Bore Bushings

[Air Cooleds Only]

Hey guys, I would like to set up for doing lifter bore bushings. I have a mill and some cutting tools for this job.

I bought a grip of tools owned by a local retired VW machinist. I have a straight reamer .875 (bushing dia) & another reamer .747 (lifter dia)

I would like to know what type of bronze material is preferred for the bushings.
I know they are offered from a couple people/shops, but I'm looking to buy in bulk , because I'll most likely be doing quite a few case's. Also if anyone knows a rough idea of press fit dimensions?
Back when I worked making aerospace parts, .001 total press fit was pretty much max.

Looking forward to your input.
Chris
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Air Cooleds Only

[gt1953]

Chris hope you do get to do that lifter bore stuff as sometimes that is all a case needs. Also gave a lady your contact info...hello Pete.
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[56vwoval]

if no radial grooving is required I'd opt for min .040" wall at finish with a press fit of .002/.003" if bronze and .001/.002" if aluminum and be sure to machine a small diameter lead of about 2mm long and a couple of thousandths under size for a easy starting, probably wouldn't hurt to preheat the case to about 180/200 degrees and apply a bit of lube to the bores as well, also make some kind of driver that won't deform them during the operation . BTW better plan on boring bushings to finish size after installation damn tuff to hit the proper clearance (.0010"/.0015") otherwise.
Don Pauter is offline
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[bugguy1967]

Silicone bronze, I think. I tried to find the raw material, but was unsuccessful.

[KROC]

You may be able to find a size that will work for you from an industrial supplier,

Try a place like this

http://www.essentracomponents.ca/product/BNT-100/1400030

[theDrew]

consider these from someone that is experienced?

http://www.thesamba.com/vw/classifieds/detail.php?id=1015025
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[Max Welton]

[the2ndcashboy]

This seems appropriate. Bearing bronze hollow bar, 1" od and .625 id. http://www.onlinemetals.com/merchant.cfm?pid=10471...op_cat=850
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[modok]

The amount pf press needed you should take into account your surface finish.
.001" press would be more than adequate with a fine honed finish.
More press can be needed the more rough and groovy the ID finish is, as the PEAKS of the surface will smush down.

lifter bore location is important. These engines have pairs of lifters, so not only is the ANGLE critical, BUT, both lifters in each side need to be the same distance back from the thrust bearing. If you plan to let the alignment "fall where it may", may god have mercy on your soul.

bronze is "cool", but aluminum tube is probably a lot less money, and will work fine. aluminum bearings do outlast bronze bearings. they do. I like bronze too, I love bronze, but if money is an issue lets be realistic.

[nsracing]

It is way easier to repair a lifter bore w/ 7075 T6 aluminum. Cheaper too, than bronze.

If you know how to run a lathe and mill, it is a no-brainer to make them. Installing them however is a little tricky. You want accurate super-fine finish at least 1/2 thou or finer for both parts. ID to OD

I like single-point boring tools when I bore the lifter bore w/ a large radius so it will be super smooth. Sure... 0.001" is plenty press-fit.

Finish boring the ID is not that big a deal. Save your money buying reamers. It is not that hard to dial-in 1/2 thou (0.0005") slide-fit.

[WhiteJawz1]

A .001 fit should get the job done and you can use Silicone bronze or rotocast.
(C932 660 Bearing Bronze)
A surface finish of 32 or 16 is required, Theres charts online if you dont know what a 32 or 16 finish is.

[Ebel]

I used 7075 or 2024 for mine I can't remember. But I made them from a scrapped part from my work. If I was going to buy new material I'd use 7075 its a bit cheaper then 2024. But any aluminum should be cheaper then bronze. Plus some bronzes come as continuous cast material which can be more work to use.

[Brian71]

If you have your heart set on bronze, 660 is the way to go. At my work, we install bronze bushings with as much as a .005" interference fit, but .001-.002 ought to work just fine for what you're doing. You would be amazed at how much you can get a part to shrink by soaking it in liquid nitrogen(.010-.015; they just drop right in). Having said that, I would advise gaining access to some for ease of installation.

[mark tucker]

as thin as the case is I would not go more than .001" interfearance.freezing is good as is heating the case a little, but if it trys to shrink down .005"....something is probably gonna crack.as in the case. you can also heat the case and messure how much it swells up at 200 or so degrees and then do the bush to see howmuch it swells,they shuld be close to the same and no issues,Ive seen some that had steel bush in them( rimco shit as I recall) the case cam expand too much and the bush could move.....no good. I got a 36" cast cored 360 for mine to go in to my new and slightly used aluminum case's with chevy size roller lifters. I may use it or just dfl coat the aluminum bores.still thinken on that. thats one of the only thing's I dont like about the aluminum cases the lifters bosses are not quite cast very well & aqlmost as small as the mag shit, and some are offset(core movement).( wish I was proficient at tigging aluminum.)