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Type 3 Front Beam reconditioning guide
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Yabbadubbadoo
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PostPosted: Sun Aug 17, 2014 2:54 am    Post subject: Reply with quote

JJM86 wrote:
Wow, this is awesome. I came across this yesterday and having just begun contemplating how to rebuild the front end on my '71 Square, what a great resource.

I read through that article about Vesconite and decided to check out their website. Looks like they have a pretty slick 'design a bearing' calculator. One can just plug in the specs on the bearing you need and it will calculate out not only the machining dimensions (taking into account expansion and machining temp, I guess) but a bunch of other factors, too.

http://www.vesconite.com/design/bush/indust/DAB_indust_metric.htm

I just ran a hypothetical bearing based on my memory of the measurements that have been mentioned in this thread and a guess on the loading and shaft oscillation and it churned out dimensions and a basic drawing. It looks like you've already achieved a working prototype but it still seems like a useful resource.

Looking ahead at the possibility of rebuilding the beam, your solution is looking really good, not to mention that it makes a lot of sense to me. I'll definitely be keeping track of your full results, great work!


Thanks, I'm inching closer.
Sorry it's been a little slow. Had a few dramas getting honest quotes and getting CNC machinists to supply the right materials. Seems some think quoting a similar product to that which I specified and calling it by the same brand name is ok to do. It's far from ok in my books. I decided that since I have no way of testing the material is what I specified then I had to buy material from the material manufacturers nominated distributor and either machine it myself or contract a machinist to do it on a 'machining-only' basis. Might sound like I have trust issues but I assure you it's not without good reason. These materials are expensive and often the colors are just the same as generic materials. If you specify Black moly filled nylon 66 derivative and some scumbag grabs black standard nylon off the shelf and machines up your whole order then it's a big problem. You may never know why the product under-performed or the bush crept out of position and you might draw conclusions that are incorrect.

Anyhow, I've decided to go with Nylatron NSM and have bought the material.
It's a material specifically formulated for bushes for hostile environments like mining equipment and heavy vehicles. It has a low k value (friction), self lubricating and it has a much higher pv (pressure x velocity) value than all other nylons and Delrin and Ertalyte without blowing out the cost massively like Vesconite did.
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eyetzr Premium Member
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PostPosted: Mon Aug 18, 2014 1:20 pm    Post subject: Reply with quote

Yabbadubbadoo wrote:
Haven't got around to making the bushes yet. Been too busy.
Thought I might show you what I picked up off a classified ad recently.

A reproduction set of lower beam rubbers cast from original by the looks of it. Looks to be a urethane type of rubber. It has the proper castor compensation built into the rubber with its asymmetric design thickness. Interested to see how durable they are. Certainly better than cracked and crushed old originals.

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Quick question, which way faces what?
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Yabbadubbadoo
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PostPosted: Mon Aug 18, 2014 5:45 pm    Post subject: Reply with quote

eyetzr wrote:
Yabbadubbadoo wrote:
Haven't got around to making the bushes yet. Been too busy.
Thought I might show you what I picked up off a classified ad recently.

A reproduction set of lower beam rubbers cast from original by the looks of it. Looks to be a urethane type of rubber. It has the proper castor compensation built into the rubber with its asymmetric design thickness. Interested to see how durable they are. Certainly better than cracked and crushed old originals.

Image may have been reduced in size. Click image to view fullscreen.
Quick question, which way faces what?


If the nose of your car is pointing toward the left of your screen then that rubber bumper on the left is in the correct orientation. You will also notice the one side of each bumper has a thicker flange. That will be easy to understand which is left and right when you attempt to install it.
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Yabbadubbadoo
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PostPosted: Mon Sep 01, 2014 1:22 am    Post subject: Reply with quote

I haven't forgotten about this project just been rather busy at work but still moving forward.

So after getting some really aweful quotes and no-quotes from people I asked to price the work I decided its just one of those in-between size jobs that would either be super expensive or just get stuffed around continually.

So I've decided to make them myself and instead of paying someone to do it I can put it toward my time and the costs I've incurred. I have access to this old beast of a lathe but my cousin who owns it never actually got around to getting it running at his factory. So I've been cleaning and setting it up to run my job since it's the only one he's got that will take the size rod I need to turn. I have purchased digital readout scales and need to fit them. I know it won't be fun to do each and every bush without some kinda x/y readout and digital zero'ing function so the digital scales are definitely going on before I get to work. In all honesty there's no way I'd do it without a readout. Reading the dials is ok for a one-off job but with x/y coordinates I can make a roadmap to follow for the repetition work so that each item is exactly the same.

I also spent some time making some custom shaped cutters to help cut the profiles and radiuses without too much trouble. I had no idea I'd spend this much time on something that on the surface seems like a simple project.
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Yabbadubbadoo
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PostPosted: Mon Sep 01, 2014 6:45 pm    Post subject: Reply with quote

The Digital readout for the lathe looks great. Reading through the manual it looks like I made a good decision buying this. They're basically designed to do this sort of repetition work using datum points and memorized co-ordinates for a series of cuts.
Still waiting for the extra long x-axis scale to arrive but that will give me time to set up the display and learn how to use it.
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mr. warehouse
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PostPosted: Mon Sep 01, 2014 9:46 pm    Post subject: Reply with quote

Nice work.
Thanks for stepping up.
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73notch
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PostPosted: Tue Sep 02, 2014 10:53 am    Post subject: Reply with quote

Very Happy Really looking forward to this! Keep up the good work.
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Yabbadubbadoo
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PostPosted: Tue Sep 02, 2014 2:41 pm    Post subject: Reply with quote

Cheers, yup I'll do the first full set and record the co-ordinate map then I'll fit them to my front beam just to double check the press-fit again before I carry on with a few more sets.
First I need to install the optical scales and readout on the lathe. It doesn't look too hard to do.
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Yabbadubbadoo
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PostPosted: Sat Sep 27, 2014 4:16 am    Post subject: Reply with quote

Finally got the Digital Readout and scales installed. Easy idea but not so easy to install. I'm just about ready to cut a few bushes. Also made a few cutters for radius cuts and special profiles for the thrust bush. CNC has made a lot of the tool shaping obsolete but I'm doing it the old fashioned way by tool-making method with a little help from the new readout.

Cable management is left up to you. I had to get mine off the floor as most people just drop the cables on the ground behind but since the swarf tray rolls out the back for emptying I had to keep the ground clear.

If you ever decide to buy a DRO expect to do a lot of improvising. The Chinese manufacturers seem to have operating instructions pretty well sorted but installation instructions are non existent.

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ataraxia
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PostPosted: Sat Sep 27, 2014 8:04 am    Post subject: Reply with quote

Patiently awaiting the first run... Popcorn
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Yabbadubbadoo
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PostPosted: Wed Oct 08, 2014 5:26 am    Post subject: Reply with quote

ataraxia wrote:
Patiently awaiting the first run... Popcorn


Getting there mate. Took me a while to get sorted. Just doing the first batch now. These are inners. I test fit them in my beam-cuts and I got a nice tolerance. It machines a little differently to Delrin and it feels more solid but just as light. Hard to describe really. I think it will work really well.


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Yabbadubbadoo
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PostPosted: Thu Oct 09, 2014 4:51 pm    Post subject: Reply with quote

Got a little more done last night. Now I have the lower inner bushes done as well as top inners. I rough cut center bore for lowers and left them well undersized as I need to know first if the shaft has been re-ground to smaller diameter like I did with my lower control arms. I expect the lower control arms are more likely for this to be done because they are the ones more likely to have score marks plus it's very hard to re-grind the top arms because they are very hard to hold on the lathe. I can explain why if anyone needs to know. Anyhow it's easy to bore the centre hole out for stock size or for 1mm undersized if it's required.

I chose to do the inner bushes first to test the water before I dive in and do the flanged outer bushes. I'm discovering what you can and can't do with this high grade bushing nylon and getting the cutters shaped just right is tricky. For example if you creep up on a particular diameter and take a rough cut first then a final cut for size say 0.5mm then you can trust your calculations but if you try to cut for exact size with too much thickness in that cut then it tends to eat a little more than you dialed in. It's not the lathe either, my lathe is a tank that is really tight, it's just a very small deflection in the nylon bar material caused by the cutting that pulls out an extra 0.3mm. There goes your nice tight fit and that affects the inside diameter too if it doesn't crush down when you press fit the bush then you have a looser fit with more play between your shaft and the bush. The two diameters (inside and outside) are interdependent. I have worked on a final fit of 0.1-0.2mm clearance for the shaft but if for example your beam housing tube is undersized compared to the two I used for measurements then it's entirely possible that you may have to do as VW did and use a reamer to get the final fit. I'm clearly trying to avoid this because not everyone has access to a reamer but I don't want to make it a loose fit either. I'm trying to hit the mark right in the middle of the variations.

Having handled a few of the old vw phenolic bushes that came out of these beams I did also notice an anomaly, the reamers they used didn't always bore a perfectly centered hole. They bored the right size but I noticed the center holes were out of center. I doubt the tubes were bent, I just think its hard to hold a reamer dead straight when it's doing its job inside the beam. I don't think it will be an issue if you're just knocking 0.1mm off to finish fit my bushes but if you had to take 2mm off it could walk off centre in my opinion.
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Yabbadubbadoo
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PostPosted: Fri Nov 07, 2014 10:59 pm    Post subject: Reply with quote

Cutting some blanks now. Takes longer than expected. Still have to set up the boring bar and radius cutter to finish the insides. I really might have to find a mob to cut these outer bushes if I can't speed up the process without losing accuracy.

I'm rough cutting the bulk center with a hole saw otherwise I'd be swamped in nylon swarf.
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Brent
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PostPosted: Sat Nov 08, 2014 3:13 am    Post subject: Reply with quote

mmm...

They look great!
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PostPosted: Sat Nov 08, 2014 6:28 am    Post subject: Reply with quote

Just wondering if anyone out there has a wrecked beam that has been chopped. I was wanting to get the top outer bearing cup and the bottom outer bearing cup if anyone has a broken beam headed for the crusher.
My reason is that Id like to test fit each bush and easily push them out again from the back side without damage. You see they compress once fitted so if it's just a smidge too small or the multiple tolerances have compounded the error you'd need to ream them out and that's not easy without a reamer. On the other hand I hate having too much clearance since the closer the fit the longer the life span so I'm trying to get it just about perfect.
I basically want a rudimentary way of checking the size after compression fit. Can't think of a simpler or more effective way to do it.
If I can't get some I'll just have to go with a wall thickness test.
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PostPosted: Sat Nov 08, 2014 7:50 am    Post subject: Reply with quote

Popcorn

Keep doin' what you're doin'!

Looking good.
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PostPosted: Sun Nov 09, 2014 2:34 am    Post subject: Reply with quote

Still doin' it. More top outer bush blanks done.
Now for the lower outer bushes.
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PostPosted: Sun Nov 09, 2014 9:00 am    Post subject: Reply with quote

Wow! Nice work!
Way to step up.

Adding a DRO to that old engine lathe just for this job?
That's commitment right there....
I ran a bunch o' different lathes back in the day.
We always would just set a few stops for a job like that. Razz

I can send you some chopped-up beam sections to use as a test-fitting jig.
Would these parts work?
Image may have been reduced in size. Click image to view fullscreen.

Might just motivate me to get my clip welded down already. Rolling Eyes

I also kept these, that I could send right away:
Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.


On another note, I would bore a set of soft jaws for the lathe to hold the parts while boring, it's the only way you are likely to keep them from being triangle-shaped from jaw crush, being all thin and soft like that...

You are really going to have to hold your mouth right when turning those suckers with them being thin like that! Wink
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PostPosted: Sun Nov 09, 2014 3:55 pm    Post subject: Reply with quote

I have the inners so thanks a bunch for the offer but in talking about the soft jaws you just gave me an idea that eliminates the need for the beam clips.
I kinda knew the outer bushes would need a soft jaw. The inners are actually quite thick and being much smaller diameter you can hold them with a light clamp without distorting but the outers well I didn't want to risk it although the flange does stiffen it up somewhat.

I think what I might do is make a set of simulated bearing cups. Basically press fit the bush (with a rough cut center hole) into a round cup made from some billet Aluminium and then throw that in the lathe and turn the inside down to exact size. Wouldn't have to allow for compression diameter shift since it's already compressed in the bearing cup. Kill two birds with one stone.
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PostPosted: Tue Nov 25, 2014 7:42 pm    Post subject: Reply with quote

This is terrific! I just got a 69 squareback which had obliterated front bearings and was able to get a craigslist replacement front end but definitely interested in rebuilding both. I am seriously interested in a couple sets of your bushings and I am beyond impressed with your ingenuity. I am very happy to see you are producing these and I can't wait for you to list them for sale!
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