Gearbox/IMS/RMS DIY thread

Thought given it's cold and wet outside I'd document this as I've found other threads on this subject interesting and useful. My gearbox has been whining for a while now and now that winter and a new round of lockdowns are here it's time to get it sorted. Along the way I'll also be doing the usual RMS replacement, IMS check along with a new flywheel and clutch and anything else that crops up along the way. I did buy a replacement gearbox that I sent to Sports and Classic but sadly it turned out to not be suitable for rebuilding due to damage to the teeth, synchros, bevel gears you name it! So I'll be using the original box and leaving the car on axle stands for a bit no doubt to the delight of my neighbours. First things first let's get the car on axle stands and remove undertrays, reverse switch and the rear chassis brace: Undo the driveshafts: Pop off the gear cables: Undo the clutch slave cylinder - this is a pain but not too tricky if you use a stubby ratchet and an extension. Luckily the slave appeared to still have it's rubber cap on the end of the shaft in good condition. Then just like that it's time to undo the main bellhousing bolts. These are all 16mm apart for one 15mm which also has a nut on the back - I didn't spot this at first and assumed I'd stripped the thread here undoing it which was a relief when I found out the nut was spinning on the engine side! There is also a triple square bolt in one place for reasons unknown to all except Porsche. I made sure that the driveshafts, reverse switch, clutch slave etc were all well supported away from the transmission I have a transmission jack that I bought when I did a gearbox swap on my previous car, an E46 M3, and it makes clutch/gearbox jobs so much easier. Supporting the engine with one jack and the gearbox with the trans jack sliding them apart was easy. Once this was done I bolted up an old socket and the bolt and nut combo that has surprised me earlier into the corresponding hole in the engine which allows the engine to rest on the cast aluminium cross member. This makes moving around under the car much easier. Then just get the gearbox out: And using my beautiful fiancee's 987 the gearbox was taken to a local repair shop: I'm very pleased with the condition of the underside of the car, I reckon it must have been garaged earlier in it's life. No signs of corrosion on the brake pipe over the gearbox. So next on the list while I'm waiting for the gearbox to be rebuilt is inspect and most likely replace the RMS, and inspect the IMS bearing. To this end I spent my lunch break in the small workshop we have at the office making a cam holder tool. This was made using the drawing shared widely online, however this drawing is not very well done so I'll publish an updated and accurately dimensioned drawing once I've figured out what fits. I'm not a very good machinist but it's always good to practice. We shall see how well this works! Finally a couple of questions: I've just done an oil change. Do I need to drop the oil to check the IMS bearing> What is the best place to go for the RMS? I see the Elring RMS is widely available and a useful £50 cheaper than the Porsche part and also seems quite highly regarded. Is this a worthwhile saving or should I spring for the genuine parts?

:thumbs:

Good stuff! Oil needs dropping as the ims is submerged below oil level when its in the sump.

If you think the slave cylinder was tricky getting off, just wait until you re-fit it back on. Best way I have found is, line the push-rod up with the clutch arm then push and slide an Allen key in the bottom bolt hole to keep it lined up while you struggle to get the top bolt started. Did you drop the engine mounts any, you can get some extra space to get around the gearbox and associated parts if you drop the engine mount nuts around an inch? The RMS is only £20 from Porsche just get the genuine one, I think it was updated with a 997 part number, 99710121201 I assume it's the same for both 3.4 and 3.6 engines?

Watching thread with interest.

Ah that's not so bad. Will give porsche a ring tomorrow.

Hi Is your RMS leaking? If its dry no need to change IMHO. I recently had my gearbox et al (a tiptronic) out in my 986 so I shall be watching to see how you get on on a 996. Best of luck! Berni

Twice I've had my box off and twice ive left the rms. if it aint broke......

Flywheel will be coming off tomorrow so I can have a look. It's not obviously leaking but I suspect there is a bit of a weep. It's peripheral to me checking the ims bearing really. If its leaking it'll be changed if it's fine I'll leave it.

Great stuff! In the spring I plan on doing the gearbox out to get the whine sorted too. That doesn't look as bad as I thought. Didn't quite get the bit about bolting the engine back to the cross member using an old socket, plus the nut bolt from the gearbox, so it doesn't need support, but I'm sure it will be obvious when I see it. Edit. Scrub that, I can see it now in the photo of the clutch. Top Tip. I had a look at transmission jacks but they were all too tall. I take it your one sits low? Who is doing the gearbox? I had seen Sport & Classic, I think they were called, who seemed to know their stuff on these. A very useful thread. Thanks!

it'll be your ims plate leaking I bet.

Just out of interest, what is the cam holder tool needed for? Isn't this only if you actually want to remove the IMS bearing, or am I missing something?

I'm furloughed today and tomorrow so cracking on. Removed the flywheel, held in place by some wire and gearbox/clutch bolts as I undid the fasteners. Really no need for a fancy flywheel holding tool: They're bloody tight though so a big breaker bar is required, and the Torx features are very low profile so make sure you are properly seated before trying to undo. You can also see the socket + bolt combo holding the engine up here too. One gold star to Alex who correctly guessed the RMS is fine and there is some minor leakage of the IMS seal: If I wasn't planning on checking the IMS I would have just cleaned this up and left it TBH. Crankshaft locked with 8mm drill bit - took a few turns over to get this seated! Timing looks good: This is the cam closest to the waterpump as specified in DeMort's message on this (very helpful!) thread: http://911uk.com/viewtopic.php?t=124928&postdays=0&postorder=asc&start=20 As YPVS says in the workshop manual it doesn't say it's necessary to lock the cams to inspect the IMS, just to remove the two tensioners for the chains on the flywheel side of the engine - one for the IMS chain, the other for the Bank 1 Cam. I've drained the oil which has barely done 1000 miles - how annoying! And am just checking and double checking the engine position before I undo the tensioners and pull the IMS cover. I would much rather do this with the cam lock in place but the workshop manual doesn't stipulate this as a requirement and the part that I've made definitely doesn't fit. the feature in the cam is barely 4mm, not 6mm as widely shared online. Maybe this is different on the 5 chain engine and the 3 chain engine? EDIT: This is the correct orientation of the cam nearest to the waterpump - which is the exhaust cam on bank 1 - from the thread above:

It isn't. You just need to slacken the tensioner off at that side and lock the crank.

That's a great tip, took a lot of of fiddling and swearing to get the bolts back in on mine..... Regarding locking the engine by lining up the 8mm hole with the opening in the block - it took me several goes. I found the easiest way was to put a borescope in the hole in the pulley and then rotate while watching the borescope screen, otherwise I kept going past it..... I recently checked my IMS and found it leaking. I replaces the o-ring on the IMS shaft as well as a new IMS seal. Neither were expensive. But my leak wasn't from either, it was from one of the 3 bolts, so definitely seal those properly (or buy new bolts, that come with sealant). I removed the dust-cover off the bearing, while I was there..... Have you checked your brake-lines in the clips, thats where they tend to rot, rather than on the long runs. I guess vibration causes the clips to wear the coating and also traps the moisture... Have been pleasantly surprised that these cars are pretty straightforward to work on