The very first track session with the 86 was overall pretty good. I’m getting more comfortable with car, and the last thing I want are expensive damages that could have been prevented. After the last track session, I noticed a whining noise getting louder each lap but I didn’t really hear how bad it was with my helmet on.

Well, driving back to my house was brutal. The whining was soo loud, you would think I have straight cut gears, or in a airplane. I’m pretty sure other cars on the road could hear it. The 40 min drive gave me a headache and thought of just putting my helmet back on at one point. I know I had to address this issue before my next track day. The whine would only happen with throttle input and goes away on decel. This tells me the diff is going bad, and need to get rebuild.

I looked on my factory service manual, and removing the diff wasn’t the hard part, its was rebuilding the diff that was tricky. I need special tools to set up the diff correctly. I know I can mess up parts from inexperience in installation, and I didn’t want to risk it with the diff. I went to friend at Duggy’s Garage, for the help. Duggy’s Garage is a 4×4 Toyota specifically shop that I’ve taken my Land Cruiser for maintenance and mods. They never worked on AE86 but they work on diffs and since my car has a solid rear end and a Toyota, its pretty much the same stuff but just a lot smaller size.

I took my diff off, and and sent it to Duggy’s Graage. They contacted their suppliers but they didn’t offer diff rebuild kits for the AE86. Thankfully, Weir Performance offers diff rebuild kits for the AE86 and currently in stock. My friend, Thaison, mentioned of regearing to 4.77 for closer ratio because the diff is already out and might as well change it for the track. That increased the cost, but I think its worth it. The car is mainly going to hit the track and closer gear ratio will put the rpm in a good range for max power. Yeah I’ll loose top speed but its and mostly stock motor, I’m not trying to go fast in a straight line.

With that, I ordered the 4.77 gear with the rebuild kit from Weir Performance. I had it shipped to Duggy’s Garage and did their magic. After a week, I got a text from the shop its ready! I had a little bit of struggle lifting the diff into the rear end because the diff is quite heavy. I was able to get it on, with some finesse and working out in the gym.

I added the recommend gear oil and went for a test drive for initial break in. No more whining noise, and feels a lot faster then it was before. I’m still in the process of the break in period, as it is recommend to put 500 miles on the diff before hitting the track. I have 1 month before my next track day. That is plenty of time for me to put on the miles. I hope to see y’all out that the Driven and Blessed track day!