TheSamba.com :: View topic

Sun Nov 15, 2020 5:54 pm

Started dry fitting and measuring things today on the Ghia engine. I bought 3 sets of Silverline main bearings figuring I’ll use the best of what I have. Put one set in the case and measured them with my bore gauge. I came up with a clearance of .0035 on one and .004 on the other 3 against the measurement of the new crankshaft. That’s with the case torqued. the other two sets of bearings purchased from another source but same brand measure out at the .004 not installed in the case. My question is what should the clearance be? This .004 seems too big.

Sun Nov 15, 2020 6:07 pm

It's in the manual
https://www.thesamba.com/vw/archives/manuals/1971withoutguesswork/8_9.jpg

Sun Nov 15, 2020 6:12 pm

Case need align bored, not enough crush on the bearings.

Sun Nov 15, 2020 6:39 pm

Thanks, Modok. So I’m on the high side. I’m going to put those other bearings in and torque the case. See where I’m at. If they are at .004 before being put in the case what “crush” would you think I should expect? Just roughly.

The case has been line bored, decked, etc. all machine machine work is done.

Sun Nov 15, 2020 8:32 pm

did you check the line bore?

Sun Nov 15, 2020 10:00 pm

.004" isnt wildly out of spec, but it is on the high side. Make sure have the case fully torqued with the pins installed and everything. Check your measurement a few more times. It might be fine. Hard to say

Mon Nov 16, 2020 6:27 am

evanfrucht wrote: .004" isnt wildly out of spec, but it is on the high side. Make sure have the case fully torqued with the pins installed and everything. Check your measurement a few more times. It might be fine. Hard to say

Which pins are you talking about? The dowel pins? I torqued it to 25 ft lbs and I did have the dowel pins in. I need to put those other bearings in and re check it. I’m hoping it’s just the one set was not good.

Mon Nov 16, 2020 9:02 pm

Went through all three sets, measured I’m not sure how many times but end result of all the bore gauging using the digital gauge is #1 #2 and #4 comes out at .003 clearance and #3 .002 when all torqued down. That’s with the 1st set. Took me a while. Those were the most repeatable numbers meaning once I got things set up right that’s what I got every time. Haven’t used a bore gauge for a while. Not something I do everyday. Had to watch YouTube as a refresher on how to read my micrometers and how to use bore gauge. It’s been a while.

Tue Nov 17, 2020 8:09 am

carguytroy wrote: Went through all three sets, measured I’m not sure how many times but end result of all the bore gauging using the digital gauge is #1 #2 and #4 comes out at .003 clearance and #3 .002 when all torqued down. That’s with the 1st set. Took me a while. Those were the most repeatable numbers meaning once I got things set up right that’s what I got every time. Haven’t used a bore gauge for a while. Not something I do everyday. Had to watch YouTube as a refresher on how to read my micrometers and how to use bore gauge. It’s been a while.

I drove my self bananas learning to use a bore gauge and micrometers and like you, my measurements tend to be on the large size. I’m pretty sure I get some error zeroing the gauge on the micrometer and again measuring the main bearings in the case, especially the center main. I know my cheapie 3” micrometer is off when it’s measuring toward the upper limit of its range. You look like you’re in the ballpark and for me, that’s as much as I trust my measurements. But it’s enough to give me peace of mind. I know a lot of people don’t like plastigage, but I think it’s a good backup, at least for the center main and rod bearings.

When I tore down my last build (type 4), I found some issues that the local machinist had missed inspecting my parts like a bent crank and case bores that were excessively out of round. I had the crank measurement verified by a machinist and learned a lot about the unusual wear I was seeing in my engine. Before this, I never measured much beyond endplay, etc. Despite this, the engine ran quite well. It probably could have been a 50k engine. It’s amazing how forgiving these engines can be when just slapped together, but sometimes, they are not. As I was starting to buy parts that cost me real money or were hard to find, I have tried to build more carefully.

Good luck with your build.

Tue Nov 17, 2020 6:10 pm

Thanks, orwell84. Measuring gets old after a while but has to be done. Now on to the rods. Need to check the clearance on those then I can put some stuff together!

Tue Nov 17, 2020 7:25 pm

Also just a reminder. I know many like to run .003 max here but right from the Bently manual it says bearings number 1-3 tolerance for new parts = 0.0016 - 0.0047. Wear limit is 0.007... so technically speaking you are well within spec :wink:

I just double checked my bearing clearances today and get a hair under .003 on the split bearing like you.

Tue Nov 17, 2020 7:55 pm

Last time this was asked, I listed my own preferences also.
https://www.thesamba.com/vw/forum/viewtopic.php?p=9376755

Tue Nov 17, 2020 8:10 pm

orwell84 wrote: When I tore down my last build (type 4), I found some issues that the local machinist had missed inspecting my parts like a bent crank...
That's some low hanging fruit for a professional machinist to miss on an engine build...

Wed Nov 18, 2020 1:24 pm

Here’s a pic from a recent motor I just built. I have several posts on my Instagram page about this subject.

The bearings are all over the place. They vary in sizes from box to box. First, check your align hone without any bearings. Verify that is all ok. Then find the thinnest or thickest bearings out of multiple sets to get your clearances where you need them. It’s like mixing .001” and std bearings except they aren’t intentionally under or over size by .001” 😅

We are in talks with Mahle about having a quality type 1 VW main bearing made with .001 -/+ sizes available.

Good luck ✌🏽

Wed Nov 18, 2020 1:53 pm

Stef, good to see you here! Your picture is a perfect example of the problem, and why you can't just slap bearings in and bolt it together.

Brian

Wed Nov 18, 2020 3:27 pm

StefACE67 wrote:

Here’s a pic from a recent motor I just built. I have several posts on my Instagram page about this subject.

The bearings are all over the place. They vary in sizes from box to box. First, check your align hone without any bearings. Verify that is all ok. Then find the thinnest or thickest bearings out of multiple sets to get your clearances where you need them. It’s like mixing .001” and std bearings except they aren’t intentionally under or over size by .001” 😅

We are in talks with Mahle about having a quality type 1 VW main bearing made with .001 -/+ sizes available.

Good luck ✌🏽

From what you found, does the manufacturer notice this.

In other words, did you find that the 2 split bearings in each box would match atleast? Or were you getting two different sized halves per "set" / box

Wed Nov 18, 2020 9:11 pm

evanfrucht wrote:

From what you found, does the manufacturer notice this.

In other words, did you find that the 2 split bearings in each box would match atleast? Or were you getting two different sized halves per "set" / box

Negative, they are all over the place. The same box can have a center main thats .0001” to as much as .0012” vs the other centre main in the same box.

It’s down to poor quality control. I have tried VW Mexico and newer Kolbenschmidt non steal backs and they are even worse. I have always put up with it and since I have lots of sets on the shelf I can find the sizes I need. I have some NOS KS bearings on the way and will try those abs report back. But ultimately I hope to be able to work with Mahle and produce a quality type 1 bearing for everyone to eradicate this problem. You will still need to set the clearances, this is a basic engine building practice as I’m sure you know, but the hope is to have consistent sets of bearings on the shelf in std, + .001” and - .001 so you can really dial in your clearances.

Wed Nov 18, 2020 9:12 pm

Brian_e wrote: Stef, good to see you here! Your picture is a perfect example of the problem, and why you can't just slap bearings in and bolt it together.

Brian

Hey dude! Good to see a friendly name here! I have been on here for a while but today was my first post 🤣🥳

Wed Nov 18, 2020 10:10 pm

StefACE67 wrote: the hope is to have consistent sets of bearings on the shelf in std, + .001” and - .001 so you can really dial in your clearances.
that would be GREAT, even JUST the center main.

The others I can deal with, but the CENTER main we are at the mercy of the supplier.

Thu Nov 19, 2020 6:29 am

StefACE67 wrote:

Here’s a pic from a recent motor I just built. I have several posts on my Instagram page about this subject.

The bearings are all over the place. They vary in sizes from box to box. First, check your align hone without any bearings. Verify that is all ok. Then find the thinnest or thickest bearings out of multiple sets to get your clearances where you need them. It’s like mixing .001” and std bearings except they aren’t intentionally under or over size by .001” 😅

We are in talks with Mahle about having a quality type 1 VW main bearing made with .001 -/+ sizes available.

Good luck ✌🏽

Good luck with that. Putting bearings in the box that actually matched what was printed...on the fucking box would be a great start. Since they obviously can’t manage that, I doubt they are going to be able to produce bearings which differ in .001” increments and label them as such...on the box.

Clearly their equipment just can’t hold tolerances. They would have to measure and sort each bearing before packaging and labeling them. I can’t see that happening unless people were willing to pay more for bearings within spec or just the regular price for ya get what ya get.

Maybe it has always been like this and it’s just that precision measuring tools are now more often found in the hands of home engine builders. Maybe in the old days people just trusted the machinist and ran the bearings they got. If the crank turned smoothly and felt good, being a little loose or a little tight would not going to make much difference for many miles especially on the mains for a stock build. Maybe lower oil pressure earlier than expected in the engine’s service life. But then again, in the old days you wouldn’t have been watching oil pressure and temp gauges sword fight their way across tens of thousands of miles.