Latest UOA's Engine, Trans, Diff
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Joined: Sep 2003
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From: Carolinas
Originally Posted by starchland' timestamp='1363442209' post='22407716
Any chance you have a pic of the drain plug magnet? Or how much was on there? Thanks for the new reports.
It was well coated with ferrous shavings, but I honestly didn't look at it closely enough.
\rlr
Carolina
Registered User
Joined: Nov 2003
Posts: 1,729
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From: Magnolia, TX
My latest Diff UOA.
Info:
- Amsoil Severe Gear 75W110 (Oil Analyzers incorrectly listed the sample as 75W140 - and this impacts the 100C Viscosity analysis note).
- Total miles on this sample was 13,487 (the longest interval I've used to date for the diff).
- This sample was the third fluid change since the diff was built.
- The first fluid change was to 75W140 (listed as 1 on the analysis).
- The second fluid change was to 75W110, and was not sampled as I only left it in the diff for less than 500 miles - due to the high Silicon contamination in sample 1.
- The third fluid change was also 75W110.
[attachment=40635:S2000 UOA Diff Jun13.pdf]
- Silicon was still high either due to residual contamination from the build (polishing abrasives used in the build process - PuddyMod Stage 4) or from contamination through the top vent on the diff. I plan on getting my car on a lift and checking to make sure I'm not missing the cap on top. My gut feeling is it's residual in nature.
- Nickel was slightly high and consistent with the first sample. I'm not concerned because this number is in essence lower because there were about 42% more miles on this sample.
- Iron numbers decreased. Again, with significantly more miles on the sample.
- As noted above - the 100C Viscosity number is listed as "Moderately Low" - but it is not (Amsoil listed virgin number at 21.1 and 20 is well in the normal range for a 75W110). Oil Analyzers failed to recognize this sample was 75W110 and not 75W140 (the first sample listed).
Overall, not bad results and I think this UOA shows the diff is probably fully broken in at this point. I anticipate follow-on numbers (especially iron) to go down from here. I think I will set a maximum drain interval of 10,000 miles on this oil though - based on the results, to include the oxidation number.
Info:
- Amsoil Severe Gear 75W110 (Oil Analyzers incorrectly listed the sample as 75W140 - and this impacts the 100C Viscosity analysis note).
- Total miles on this sample was 13,487 (the longest interval I've used to date for the diff).
- This sample was the third fluid change since the diff was built.
- The first fluid change was to 75W140 (listed as 1 on the analysis).
- The second fluid change was to 75W110, and was not sampled as I only left it in the diff for less than 500 miles - due to the high Silicon contamination in sample 1.
- The third fluid change was also 75W110.
[attachment=40635:S2000 UOA Diff Jun13.pdf]
- Silicon was still high either due to residual contamination from the build (polishing abrasives used in the build process - PuddyMod Stage 4) or from contamination through the top vent on the diff. I plan on getting my car on a lift and checking to make sure I'm not missing the cap on top. My gut feeling is it's residual in nature.
- Nickel was slightly high and consistent with the first sample. I'm not concerned because this number is in essence lower because there were about 42% more miles on this sample.
- Iron numbers decreased. Again, with significantly more miles on the sample.
- As noted above - the 100C Viscosity number is listed as "Moderately Low" - but it is not (Amsoil listed virgin number at 21.1 and 20 is well in the normal range for a 75W110). Oil Analyzers failed to recognize this sample was 75W110 and not 75W140 (the first sample listed).
Overall, not bad results and I think this UOA shows the diff is probably fully broken in at this point. I anticipate follow-on numbers (especially iron) to go down from here. I think I will set a maximum drain interval of 10,000 miles on this oil though - based on the results, to include the oxidation number.
Joined: Jan 2006
Posts: 4,953
Likes: 25
From: 17 ft below sea level.
Thanks for posting 
In a diff that is breaking-in, its hard to tell what does what and why.
Nevertheless this UOA allready shows good results and most likeky will improve.
What was the brand / type of the 75W-140 oil(s)?
Once you get a steady iron ppm level with the 110, you could try the 140 - Amsoil(?) - again and see.
(please
)
Wouldn't the cadmium be the Torsen thrust washers?
They are coated.. right?
Based on pictures Puddy posted.
That coating does exactly what they describe: low friction alloy.
I'll end with a question:
How do you like the handeling now?
Any difference with the old diff, especially around (tight) corners and during on-the-throttle corner exit?
Be honest
In a diff that is breaking-in, its hard to tell what does what and why.
Nevertheless this UOA allready shows good results and most likeky will improve.
What was the brand / type of the 75W-140 oil(s)?
Once you get a steady iron ppm level with the 110, you could try the 140 - Amsoil(?) - again and see.
(please
)Wouldn't the cadmium be the Torsen thrust washers?
They are coated.. right?
Based on pictures Puddy posted.
That coating does exactly what they describe: low friction alloy.
I'll end with a question:
How do you like the handeling now?
Any difference with the old diff, especially around (tight) corners and during on-the-throttle corner exit?
Be honest
Thread Starter
Registered User
Joined: May 2011
Posts: 529
Likes: 0
From: Indianapolis
No problem.
Since this thread has been updated I will add that I have my Puddymod diff on the way and should be here Monday. Per STR rules, this is simply a rebuilt stock AP1 unit with the OS Giken LSD.
I will post more after I get it installed and do the break-in procedure. I plan to sample/test the fluid.
Joined: Feb 2004
Posts: 1,491
Likes: 11
From: Pensacola
thanks for posting slipstream. i think your new diffy is doing just fine now. although i think le came up with a wiinner in 1605, i can now recommend svt 75w-110 as a viable alternative based on finally seeing some wear trending data. hopefully, birdshot will see some improvement soon too with the svt.
Nevertheless, since my last UOA of Amsoil 75W110 came back with better and stabilized numbers after the break-in - I think I'll stay with it for now. Although Spitfire has a good point in that my diff may be better suited for 75W140 - especially for summer driving. I may switch to it next summer. I will keep an eye on my diff numbers and post future analysis.
Bird Shot: thanks for all the info - and sorry for the mini-hijack. I think you'll be very pleased with the Puddy-Mod Diff.
Spitfire - I can't say how much of my handling is due to the improved diff or the next-day installation of the KW Variant 3 suspension (and corner balance). I would have to say the biggest difference in handing has been the Pilot Super Sports I recently installed. The best tire I've ever run on my S2000. My car digs so hard into corners now I am worried I'll starve the engine of oil. I press my car harder into my favorite turns and still can't get the car to break loose by much. I'm concerned the grip limit is well beyond the stock oil supply's G limit at this point. The car just tucks and keeps pulling. My next mod will be a baffled oil pan (any reasonably priced suggestions?).
Joined: Jan 2006
Posts: 4,953
Likes: 25
From: 17 ft below sea level.
Have you ever considered the Advan AD08?
Or the RE-11, or the latest Dunlop Direzza II, or.. or...
There are many types and it seems like everyone likes another best.
I'm concerned the grip limit is well beyond the stock oil supply's G limit at this point. The car just tucks and keeps pulling.
IMO modern day "super sport" dot legal, ect. tires are better than 1999 semi slicks, IF they were available.
Certainly better than the good old S-02's.
More grip around long tight corners IS a RISK.
Did you do anything about the front sway?
I mounted a stiffer front sway to compensate for added front grip to get the F/R grip blance back.
The ration between S-02 front and rear width is impossible to find in modern tires.
My next mod will be a baffled oil pan (any reasonably priced suggestions?).
https://www.s2ki.com/...affled-oil-pan/
the common baffled pan is not that helpfull.
One needs a trapdoor (= a one way oil flow basically) pan to actually hold the hot (= thin!) oil around the pump intake.
I'm using the Spoon baffled pan after my engine issue on semi-slicks a couple of years ago.
Just because I felt like doing something, anything, to stop this from happening again.
Spoon was the only one available in Europe at a reasonable price, that's why I picked that one.
So far so good but I have not been at a track since but I do use the AD08's.
Your description on the handeling makes me think: diff!
IMO it's an important factor in rear grip on corner exit as doing that the diff (oil) has to deal with a huge conflict.
The difference in rotation makes it think there is slip (so lock) but the grip forces it to differentiate (allow slip)
The oil has to make sure parts can slide in relation to eachother while being pushed together at great force.
edit: typo's
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