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Checking a Briggs v twin crankshaft

#1

Stryped

Stryped

I have a Briggs v twin town appart. Is there a way for me to check if the crank is bent at home? I have a dial indicator but can’t quite figure out how to do it. Any help is appreciated!


#2

sgkent

sgkent

you could make a set of V blocks from even hard wood and try using the dial indicator on different spots. The issue would be that it it has only two journals it could still be twisted. You might look at the wear pattern on the bearings with good eyes to see if they show even wear. Put the dial indicator on a steel plate if it is magnetic. I'd try the tip all the way out at the end of each journal and then in as close to the center end of each journal to see if there is any change as you rotate it slowly. The bearing surface should not rise and fall I should think. Without a flat machinists' table and some precision V blocks it would be hard to detect minor twist in a rod journal I think. The only way I can see it done really accurately is to measure the distance from the table to each side of the rod journal while the main journals are supported on V blocks to be sure the rod journals are parallel. A crank grinder could tell you easily on their jigs. Unless you hit something really hard it would be unusual for one to bend I think. You might mic the journals to be sure they are still in spec too because it could be straight but still worn out.

Basically a crank could twist along the main journal plane without changing that plane but it would be likely that if it was bent the main journal plane would be out a little too so you would see the needle move in a consistent pattern as you carefully rotate the crank in the V blocks.


#3

Stryped

Stryped

I replaced the sump gasket due to an oil leak and it immediately broke a rod shortly thereafter. I remember when I did the gasket having difficulty with putting on a new oil seal. If I put the seal on the sump cover first and then tried to install the sump cover the seal lips would curl and mess the seal up. I ended up having to install the sump cover first, then the seal to get it to work.
it made me wonder if the crankshaft was tweaked or something.


#4

R

Rivets

It would be very, very unusual that you have a bent crankshaft if you didn’t hit something. I’m guessing the rod broke due to another cause, like a crankcase cover not tighten properly or cam jumping a tooth when you had the cover off. Or you know $@8?¥€§ happens and you may never know why.


#5

B

bertsmobile1

I replaced the sump gasket due to an oil leak and it immediately broke a rod shortly thereafter. I remember when I did the gasket having difficulty with putting on a new oil seal. If I put the seal on the sump cover first and then tried to install the sump cover the seal lips would curl and mess the seal up. I ended up having to install the sump cover first, then the seal to get it to work.
it made me wonder if the crankshaft was tweaked or something.
That is the way I do all my oil seals
If they are not tight then they can not do their job
The trick is to polish the crank and lube it before you start
Chances are when you replaced the sump you did not get the oil pump aligned .
A photo of the rod , bore and the piston inside & outside would allow us to give you a better idea why it broke


#6

Stryped

Stryped

I can’t add a photo. It always says file too large


#7

Stryped

Stryped

I can’t add a photo. It always says file too largest do you mean oil pump alighned


#8

Scrubcadet10

Scrubcadet10

I can’t add a photo. It always says file too largest do you mean oil pump alighned
try here https://postimages.org/ and then paste the direct link here.


#9

B

bertsmobile1

I can’t add a photo. It always says file too large
Mobile phones use a format called RAW
The internet sees RAW files nearly 10 times bigger than they are
So photos need to be downloaded into a photo editing app on a computer of some sort
Then SAVED as a JPG (JPEG for superiour computers )
Now if you want to be really sure it will upload to the forum then resize the photos to 12" along the longest side and change the resolution to 72 dpi.
That takes a 2 GB image down to 500 kB but will display full screen on most computers very clearly .

Phones cheat and add a lot of pixels that they actually did not capture so the can pretend to be taking very high resolution photos .
But because of this the meta data tag shows the file size as being XYZ Meg when in reality it is 1/10 that size .

If you think this is tosh then check the file size of a photo on your phone, then multiply it by the number of images you have there and suddenly it is 5 times bigger than the phones memory and that is before all of the music which does have really big files .

This is a photo reduced to 720 kB
As you can see plenty of detail
People think if the make the image size smaller it makes the file size smaller but it does not work that way.
You have to change the resolution .
FWIW this is 12" @ 72 dpi.
Commercial.jpg


#10

StarTech

StarTech

And here I use an Pixel size of 640 x 480 for most images which is actually a VGA spec that my phone uses.
but the image Bert posted converts to as follows (some of image crop as not need to the spec):
1651233222362.png


#11

S

slomo

Mobile phones use a format called RAW
I've never seen nor heard of a silly phone that shoots in RAW. Like you said, huge file sizes. Most are jpg files.


#12

S

slomo

I can’t add a photo. It always says file too large
1651269780872.png
1651269843006.png
Working over here....


#13

sgkent

sgkent

I upload to computer and use Snagit to crop and save. I pay for it but they have a free trial with no credit card needed. https://www.techsmith.com/screen-capture.html


#14

T

Tinkerer200

I think it would be incredible to twist or affect alignment of the crankshaft of a B&S V twin. As for installing seals, they make a tool for that but IF I experience problems, I wrap a short pc. of thin plastic film around the upset area and slide the seal on.

Walt Conner


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