Just rebuilt my AP2 diff... with good results!
04-27-2009, 08:02 AM
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Just rebuilt my AP2 diff... with good results!
I installed an AP2 diff w/ 40k miles on it over the winter, but I guess the previous owner had abused it and there was no preload on the pinion left and it just progressively got worse. Special thanks to Ben for helping me diagnose this. I remembered spinning the input flange when I first got it and there was almost no resistance at all. Little did I know at that time that this wasn't normal. The car became more and more jerky changing between acceleration and deceleration and the whine started getting louder and louder. I wanted to take it to the autocross on sunday so I decided to rebuild the diff on Saturday. If you need step by step instruction, there are a few threads on with photos and the Honda manual can be found scanned into PDF. Maybe on my next rebuild I'll write a DIY. Here is at least some insight into my experiences and tricks I learned that may help you.
The bearings looked good so I didn't replace them. I just replaced the seals and the crush sleeve and set everything back to the tighter side of the factory specs. I found the easiest way to remove the seals was to tap the backside of them with a long screwdriver and a hammer. It's a lot easier than prying them out like the Honda manual suggests. The easiest way to set the seals was to use extra large sockets. My friend had a full set from 1" to 2" and two of them were the perfect size. The easiest way to hold the pinion flange is to just take a long piece of aluminum stock and drill 2 holes in it 40mm apart and bolt it onto the flange. Gears also looked smooth. I also used some Grade 10.9 Bolts w/ 17mm wide heads to help support the load since I didn't have the time to make bearing caps.
Turning force is set to 12 lb/in on the Pinion. I tightened the nut up to 150 lb/ft and couldn't get to 12 lb/in so I backed the nut off and torqued it down again to about 170 lb/ft. Backlash is set to .003" and there is less than .0005" difference across 4 points on the gear, 90 degrees away from each other. Ring preload is 5 lb/ft. I didn't have a push/pull gauge so I used two methods to check. First I used a torque wrench on one of the ring bolts and divided that reading by 2.75 since I had about that much leverage from the center. I also put an approx 1.5 lb screwdriver carefully in one of the LSD openings and hung a 4lb bucket of water from it at 1ft away.
I also didn't have blue marking paint, so I used white lithium grease. Contact pattern came out perfect dead center.
I'm happy to report that there is no more jerking or whining! I put in some cheapo conventional fluid to break it in for the first 100 miles and am changing it out today to some durablend for the next 500 miles. After that Amsoil 75W140 is going in. It's the multi weight that's got the closest viscosity to the factory fluid and is slightly thinner at lower temps (to help with cold splash) and is only slightly thicker at higher temps, which I don't mind during the summer. Shear stability of the multiweight shouldn't be a problem with Amsoil's high grade synthetic base stocks and EP additives.
Sorry I didn't take many photos this time. I was busy trying to finish it in time for the autocross. Suggestions, Comments, and Questions are welcome!
Steven
The bearings looked good so I didn't replace them. I just replaced the seals and the crush sleeve and set everything back to the tighter side of the factory specs. I found the easiest way to remove the seals was to tap the backside of them with a long screwdriver and a hammer. It's a lot easier than prying them out like the Honda manual suggests. The easiest way to set the seals was to use extra large sockets. My friend had a full set from 1" to 2" and two of them were the perfect size. The easiest way to hold the pinion flange is to just take a long piece of aluminum stock and drill 2 holes in it 40mm apart and bolt it onto the flange. Gears also looked smooth. I also used some Grade 10.9 Bolts w/ 17mm wide heads to help support the load since I didn't have the time to make bearing caps.
Turning force is set to 12 lb/in on the Pinion. I tightened the nut up to 150 lb/ft and couldn't get to 12 lb/in so I backed the nut off and torqued it down again to about 170 lb/ft. Backlash is set to .003" and there is less than .0005" difference across 4 points on the gear, 90 degrees away from each other. Ring preload is 5 lb/ft. I didn't have a push/pull gauge so I used two methods to check. First I used a torque wrench on one of the ring bolts and divided that reading by 2.75 since I had about that much leverage from the center. I also put an approx 1.5 lb screwdriver carefully in one of the LSD openings and hung a 4lb bucket of water from it at 1ft away.
I also didn't have blue marking paint, so I used white lithium grease. Contact pattern came out perfect dead center.
I'm happy to report that there is no more jerking or whining! I put in some cheapo conventional fluid to break it in for the first 100 miles and am changing it out today to some durablend for the next 500 miles. After that Amsoil 75W140 is going in. It's the multi weight that's got the closest viscosity to the factory fluid and is slightly thinner at lower temps (to help with cold splash) and is only slightly thicker at higher temps, which I don't mind during the summer. Shear stability of the multiweight shouldn't be a problem with Amsoil's high grade synthetic base stocks and EP additives.
Sorry I didn't take many photos this time. I was busy trying to finish it in time for the autocross. Suggestions, Comments, and Questions are welcome!
Steven
04-27-2009, 02:22 PM
#2
Nice! I'm rebuilding a blown diff... the ring threw up CHUNKS of metal. I'm not taking any chances with the bearings (even thought they do look good) and I'm replacing all of them (except the 2 on the LSD). I just got my new OEM seals, bearings, nut, etc from Rick's the other day and I still need to order a new pinion and gear from Kia 
. I'm assuming you didn't need a new thrust washer?
I hear ya on the oil seals... the Helms manual makes it look like you can simply pry out the old seals when a hammer + screw driver does the trick.
I'm to update my progress after I install the new seals and stuff... you can check out my thread ->
https://www.s2ki.com/forums/index.php?showtopic=683994
Keith
. I'm assuming you didn't need a new thrust washer?I hear ya on the oil seals... the Helms manual makes it look like you can simply pry out the old seals when a hammer + screw driver does the trick.
I'm to update my progress after I install the new seals and stuff... you can check out my thread ->
https://www.s2ki.com/forums/index.php?showtopic=683994
Keith
04-27-2009, 02:49 PM
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that's some serious damage. I'm glad your bearing caps are still good. I didn't need a new thrust washer because it was the same gear set in the same housing.
04-27-2009, 03:03 PM
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Hey, next time you do it could you do a write up? I'd love to swap out my own gears/learn how to set backlash, etc etc. I also want to upgrade the diff so it wont shatter when I go add power to the car..
04-27-2009, 07:18 PM
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Originally Posted by SoCalIsMyLife,Apr 27 2009, 05:49 PM
that's some serious damage. I'm glad your bearing caps are still good. I didn't need a new thrust washer because it was the same gear set in the same housing.
Keith
04-28-2009, 05:08 PM
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It took me about an hour to remove it and an hour to put it back, just because I'm using hand tools and jack stands. Follow the honda manual and take the 4 nuts off the back of the diff but leave the front aluminum mounts on and take the 4 bolts off the rubber mounts.
Just changed the fluid today to Valvoline Durablend 85W-140 and will leave it in for about 500 miles. There were a bunch of tiny flakes about 1mm wide. They may be debris that the bearings chewed up or it could just be that I was using used bearings and it wore away the old race.
Anywho it feels great and smooth with no noise or jerking
Just changed the fluid today to Valvoline Durablend 85W-140 and will leave it in for about 500 miles. There were a bunch of tiny flakes about 1mm wide. They may be debris that the bearings chewed up or it could just be that I was using used bearings and it wore away the old race.
Anywho it feels great and smooth with no noise or jerking
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