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pfrederi

10 Pinion Spring issues

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Working on a 10 pinion Limited slip differential.  The cylindrical spring that make the limited slip work has deep gouges in it that matchs the pinion gear teeth.  Since these parts mine in relation to each other in nomal use I am wondering what causes the gouges.

IMG_0101.JPG

IMG_0102.JPG

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I'd almost say they are getting caught and running in the same spot all the time - despite being spring steel the gear teeth are harder and are wearing the ring instead . I assume by design that thing has to be able to "float" just a little - maybe it's doing it too much and getting tipped a bit in that recessed area around the outside ?

Are there any wear marks on any other parts in contact with the rings at all ?

 

Sarge

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The teeth on the pinion gears all looked near perfect.  as did the gears on the end of the axles...  The inside of teh transaxle as very clean just some metal bits in teh suction screen and magnet...courtesy of the parking brake being ground down.

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You are in luck Paul if you want to change out that spring.  I have been in contact with @sfjohnson722 (Shawn) about his transmission.  He went to a machine shop and had some made.  He had some extras made so if someone needed one he would sell one.  Here is a picture.

 

new one on the right   the metal is made of 4150

image.jpeg

 

image.jpeg

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I pm'd him just now  Thank you!!

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That's great - we just need someone to start offering those as a lot of the limited slip axles get swapped for the standard 10 pinion diff instead - those limited slips do work quite well in the older Chargers and such .

 

Sarge

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All 10 pinion diffs are limited slip Sarge. Service bulletin #252 in 1979 addressed the conversion to an 8 pinion. I do think there would be a market for those springs. :)

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Yup - typo , my bad - I meant 8 pinion . I've been amazed at how well my brother in law's Charger can get around on ice and such with only stock weights - no chains but it does like to side slip on any sort of hill . The diff still works perfectly , btw....


Sarge

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Thanks for the shout out @stevasaurus! I have a few folks interested and have 5 remaining. I started with 10 of these; but I can see if we can get more made if there is a lot of interest. I tried 3 machine shops and it ended up one of the foreman decided to do it at home on the side. I don’t know how these will wear - 4150 was chosen for it’s hardness properties, workability, and cost - if someone more knowledgeable about metals can suggest something else I can inquire. I’m currently asking $20 each shipped to US addresses to cover my costs in it. PM me for payment info and address, etc.

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Quick update on the spring and clicking - I just put my diff back together with the new (perfectly smooth) spring, and it clicks. I will post a video later to my thread on the 71 Bronco rebuild. But be forewarned a perfectly smooth spring may not stop the clicking - I think it’s *supposed* to click a little.

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With the slot in the spring I don't think a click is avoidable.

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I want to talk about the "click".  I am going to offer up this video that I did some time ago...check it out.

 

Look at the differential when I turn the input shaft and the trans is in a gear.  Notice that the pinions do not rotate at all.  I submit...if you have your horse on blocks and you are running the horse in gear...if you have a click, it is not from the pinions and spring.  Those pinions will only rotate if you are not going straight.  If you read the manual on a horse that has a 10 pinion Limited Slip...the Limited Slip only works when you are going in a straight line.  It works like any other differential when you are not going straight.  I think that we all think that these pinions are turning all the time...I now think, if you were going in a straight line for 1 mile...they would not rotate at all.  :think:

   A good test of this would be to have your horse on blocks and running in gear.  If you have a click, it is not from the differential internals.  If you go a head and hold one of the wheels and you get a click...the click IS in the differential internals.  So where would the click be??

   My guess...if all the bearings are good...would be a touch of slop somewhere around the input shaft / hi-low / fork / spring mechanism.  What do you guys think??  :occasion-xmas:

 

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Posted (edited)

I should put this in my rebuild thread, but until I get a chance to update it I’ll put it here for the sake of conversation. I agree with @stevasaurus, and I think @953 nut is on to something. Originally I thought the click was from the wear grooves alone, and it certainly was worse with them. But after trying the new one, there is still a click probably because of the notch and perhaps also that not all of the 10 pinions are ‘tight’ against the shell at any one time (prove this by flipping a shell half over and 1-2 pinions fall out with 3-4 held in place with the spring) - perhaps as the spring rotations when the diff is engaged it slaps the pinion against the shell. Anyway, the clips:

IMG_3846.MOV

IMG_3876.MOV

Edited by sfjohnson722
videos did not upload originally
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On 1/2/2018 at 8:40 PM, sfjohnson722 said:

I should put this in my rebuild thread, but until I get a chance to update it I’ll put it here for the sake of conversation. I agree with @stevasaurus, and I think @953 nut is on to something. Originally I thought the click was from the wear grooves alone, and it certainly was worse with them. But after trying the new one, there is still a click probably because of the notch and perhaps also that not all of the 10 pinions are ‘tight’ against the shell at any one time (prove this by flipping a shell half over and 1-2 pinions fall out with 3-4 held in place with the spring) - perhaps as the spring rotations when the diff is engaged it slaps the pinion against the shell. Anyway, the clips:

IMG_3846.MOV

IMG_3876.MOV

 

 

In the second clip the tires are rotating opposite each other.  if the LTD Slip was working shouldn't they turn teh same way????

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In that video the parking break is on and hydrogear is installed, so no I don't think so. But if the brake was off and low / no resistance from the hydrogear then yes I believe they would turn together. Please correct me if I'm wrong.

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17 hours ago, sfjohnson722 said:

In that video the parking break is on and hydrogear is installed, so no I don't think so. But if the brake was off and low / no resistance from the hydrogear then yes I believe they would turn together. Please correct me if I'm wrong.

Went out and jacked up the rear on all three of mine and worked the way you showed ...my mistake

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I might very well be interested in a spring or two too, but if you are making another batch, I would like to suggest having some made of thicker material, so it locks up harder. Perhaps a few different options.? +20% +40% +60% force etc. ? Trick is to find the right force for a given tractor setup where you do not rip up the lawn, and still get so much lock that you almost do rip it up, and still do not loose too much steer-ability. That will vary from tractor to tractor depending on a bigger number of factors.

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To those I've shipped springs to, it seems like the metal isn't springy enough for our purposes. As I tried to elude to in post 10, we may not have the metallurgy correct for this application. @Skipper has an interesting point, but the consensus I got from the 3 machine shops I went to was that it would be cost prohibitive to get it right.

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There are a few very skilled metal guys on this forum I'm sure. Perhaps one of them could be persuaded to fumble around with it. :-)

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I’d be interested in ponying up cash for a few if the tempering is figured out.

 

If I had one, id look for a BLACKSMITH and have him give it a go.

 

Or a knifesmith.

 

 

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