996 c4 transmission rebuild

I am undertaking the replacement of the syncros and 2nd gear on my 996 c4. The tranny has 104k mikes on it. Shifting between 1 and 2 and 3 is getting very stiff. So far it has not been popping out of gear. I have the engine out and the transmission separated. Can anyone tell me the size of this nut that holds the flange at the front end of the transmission? It seems to measure 30 mm, but before I order a thin wall socket I thought to ask the forum. The part listed on various sits does not specify the size. Also, any tips or advice or "while you are here" suggestions for this project is appreciated. This will take a while. Updates will be posted. front end flange nut - was size? Out of the car

This is the part number but i couldnt find a size. Maybe a dealer parts or service computer has it? 99630231700

The flange nut is 30mm. The flange comes off easily after you get the nut out.

Progress - taking off the cone was pretty easy. The key to driving the drift pins out of the selector arms is to raise them up so the drift pin does not hit the gear behind it. Also, take the springs and ball bearings that set the detents for the selectors out before you pull the selector shafts out. Also take out the detention with the roller for the short shift arm. The magnet was "furry" which seems to be typical. No large particles, just a fuzz of metal. I cleaned it before I took these pictures. Pull this out before you get too far. Note the orientation of the roller / slot. holes that hold the detents for the selector shafts Selector shaft detents cover off Puller on

If you want to upgrade your 2nd gear G Box detent, Amazon has them for 20 bucks. Amazon.com: VIPIH Gbox Detent Kit Fit for Porsche Transmission 996 997GT3 Boxster S Fixes 2ND Gear Pop : Automotive Amazon.com: VIPIH Gbox Detent Kit Fit for Porsche Transmission 996 997GT3 Boxster S Fixes 2ND Gear Pop : Automotive

I used two heat guns and an electric 1/2” drive impact gun to pull the gears off. The key was having enough umph to pull these off. When i got it apart I found that i needed to replace the two cone rings due to wear. One source i read said that if the teeth on the 1st gear syncro rings are ok, then just replacing the cone ring is ok. The plan is to replace all three rings on 2nd gear and just the cone on 1st gear. I appreciate thoughts on that. After reverse and first removed After 2nd gear removed

Probably a solid plan. There is actually a go - nogo measurement on the gap between the cones and the ring from the factory. Its a near impossible spec to find because its only in the fsm. Maybe u can get it from one if the builders to double check all the sycros and make sure they r not too tight?

the restacking and reassembly are completed. I used a cheap toaster oven to heat up the parts that are friction fitted or go on the splines. I heated them in for 15-20 minutes at 375 f to 400 f and except for 2nd gear and the thrust washer no pressure was needed to put them in place. a warning, after the reverse gear syncro stack is in, be very careful NOT to lift it. I did and the detents came out. One of the ball bearings disappeared on the shop floor. I was very lucky to find it. There is a good youtube video of a guy putting the springs, stones, and ***** back in. It took me just 15 minutes to get it back together. After that, putting the shift rods and arms in place was not bad either. I marked the orientation and height of the shift arms on the shaft to make it easy to line up the holes and put in the pins. The detent ***** and springs went in next. I put some thread sealant on those bolts. before i put the cone/case back on i replaced the seal at the output shaft (this is a C4). then i undertook the reported adventure getting the cone/case on. I dropped the case over the assembly and did my best to get everything aligned. I used a boroscope to see what i could, which was not much. Once things seemed aligned i pulled the shift rod with the �thimble� on it to the outside of the case with a wire tie to get the rods and shafts in the right holes. I tied it off around the shift arm. One post said they used a bungy which seems like a good idea. After that, i shimmied it around a but and suddenly the case slipped down to about 1 cm above the bottom case, i cut that rod loose and looking up through the gap i was able to lift the thimble up a small amount with a long screwdriver. I tilted the case a little away from rod and the wheel on the shift arm easily slipped over the thimble�s top ridge into place. The case dropped right down into position. I got very lucky - total time from starting to put the cone / case on to it dropping into place was less than 2 hours. i pried the cone up about 1/8-1/4� and applied sealant around the perimeter, using a small screw driver to get it around the bolt holes. The bolts went in and are torqued. The output flange went in to the new oil seal and was bolted down. i put in a new RMS, resealed the previously installed LN engineering IMS solution oil lines, put the flywheel and clutch back on (just 1500 miles on the clutch) and mounted it back on the engine.i filled the transmission with fresh liquid moly gear oil. tomorrow it goes back in. If the snow melts here in new england i should be driving it in March. cost - with three syncro stack on and 2nd and a new syncro ring on 1st using the old outer rings, a new 2nd gear, a new syncro gear with the detents, new RMS, new output shaft seal, new flywheel bolts, new oil for the engine and tranny, and misc. sundries - total about $2,400. but the adventure and satisfaction is priceless.

Engine back in and running. Made a rookie mistake - I left the oil filler cap off as I first started it and of course it did not run well. I slept on it worrying that I messed up a vacuum line some where, or screwed up a fuel line fitting. Went to the shop and found the cap sitting on the shelf in the engine bay, popped it on, and it started like it always did before and ran like it always did. Scanner shows no codes. Happy day.

Wow! Great job� That�s a ballsy one to take on . Hope everything works flawlessly for many many miles!!! Can�t wait to hear when you start driving it

Super work. Where did you find the best info on the rebuild process? Usually people are saying you need a 20 ton press to do it so good for you on your work around. Well done. Let us know how it shifts now.

Quotes source post: 20459821

He did not get to the part where it needs a 50-ton press yet (gears 3 and 4). Just a long puller for the stuff he is doing for gear 2.

I did not do the upper gears. I have no press, and the syncros there usually are ok. Also, I read that some times the pinion bearings go, but I found no slop in anything at the ends of the big shafts. Everything for 1 and 2 and revers either slides off or come off with heat guns and pullers and goes on with heating them up and a few whacks with a PVC pipe and a dead blow hammer, or just drops on when up to temp. A great source of this is Dave at funahead-tv on you tube.

First couple test drives now that most of the snow is gone e here in southern new england. It definitely shifts easier between 1, 2, and 3rd gears. I now regret though not changing the 2nd gear detent while the tranny was out. It does not pop out but it could be better i think. I do have to pull the center console and adjust the cables. Was it all worth it? Well it was fun, but i am not sure it is $2400 better. Still, its “ cheaper than golf’. much to my discomfort the AOC relief vent at the back end of bank 2 has started to leak. I ordered the part, but it will be an adventure to replace it. I replaced the AOC last year, but should have done the pipes and vents while the engine was out. Another while you are here…. Some people have said you can cap it off, but i am not confident enough to make those modifications.

You can play a lot of golf for $2400�😏 If it was fun, that�s what counts!

Quotes source post: 20460577

I typically see about 35 tons indicated when removing 3rd through 6th gears from the pinion shaft, with a 50 ton press. I do them two at a time, rather than all four in one press. My friend Bill Pfister preferred doing all four at once because he got a kick out of having the press jump in the air and scaring the bejesus out of him. I prefer a little less drama... The sealed, double-row four-point contact bearing next to the pinion gear on that shaft is a weak point in the G96 design. They frequently go bad and the transmission gets noisy when this happens. The input shaft also has its own sealed bearing, both have an interference fit with the differential carrier (aka. bell housing) part of the case and are difficult to impossible to remove non-destructively. Yes, the inner races (bushings) will go on without fuss if you warm them a bit. Warming carefully also helps with removal, but you should be careful not to overheat the shift detents (ball, spring, anchor block), shielding them if for example using a plumber's torch to warm the inner race near to them. Cheers,