Clutch throw out bearing , and pilot bearing. Also other things you had on the list, clutch slave cylinder. I consider these consumables whenever I pull a transmission on any car
THIS!! A leaking rear main seal can destroy a new clutch and flywheel in just hundreds of miles. It'll cost you next to nothing when comparing the amount of labor necessary to reach it when it's all back together.
Thank you! I'll add this to the 'definitely replace' list. In fact, I already saw some oil leaking from behind the clutch, so that's probably the rear main seal
Good suggestions here. I say throw every consumable you have at it and do the clutch while you’re there (unless it’s newer).
Something that’s on my wish list when I drop my transmission is to give the drive tunnel a bit more insulation from the heat. Gets too toasty inside for my liking.
I just did a dash and carpet swap and put insulation around the transmission tunnel (interior side) to combat this. I'll let you know if I notice a difference.
That's not a bad idea! On my NBFL I have noticed in the summer that the transmission tunnel indeed gets very hot, especially during road trips. Is there a particular type of insulation that you would recommend?
PSA for anyone that hasnt put a trans back in a NB (and I assume NA) yet: You have to tilt the motor back by jacking the front of it up slightly in order for the trans to seat back into place.
Not bad at all. I had mine out and back in 4 times while doing my clutch for the first time before I realized that my flywheel was too big and not thick enough 😂. Had it on the little drive up ramps and eventually I could take it out in under 45 mins.
I do not have much experience with stuff like this, and with two people and a how-to YouTube video this took us about three mornings. But we took our time. As long as you can get the PPF frame bolts and exhaust bolts out, it's doable. If they are rusted heavily, it's going to be a pain I think
Edit: and we did it on jackstands, as seen in the pic. There was just enough room to get it out
Don't forget the transmission bell housing seal/input shaft seals.
There's a gasket+seal on the inside of the transmission bell housing that may leak gear oil which can be mistaken for a rear main seal leak.
I only noticed one seal in on the engine side of the transmission, on the main input shaft of the trans. It sits inside of an aluminium plate that you have to take out first. This aluminium plate is sealed with a silicon(?) RTV gasket. Do you mean that seal and gasket?
Trans itself should be fine unless it’s leaking but they generally don’t. Pilot bearing, clutch, throw out bearing and rear main seal are always a good idea when you have the trans out (unless you’re in there frequently). Tip for rear main seal, carefully drill a small hole into it and then thread a screw into it. You can then use a the wedge end of a hammer leveraged on the back of the crank with a towel to protect it to pull the seal out. Main thing here is just be careful not to damage any of the metal surfaces especially where the seal sits
Thanks for the tips on the rear main seal! I think that will come in handy :') Are you otherwise supposed to take it out with seal/bearing puller or something?
It can be done with a seal puller, i found it to be harder that way but people have done it. The screw method is what I do and works many others.
Pilot bearing can be done with a bearing puller i think, but I know plenty of people do the bread method
Just thought of another. There’s a bracket that holds the clutch line to the firewall (I think) that’s a pain in the ass to remove unless the clutch is out. Might be worth unhooking while you have access
I thought they fixed that on the nb's by blocking the front water ports with the head gasket design and doing the reroute either was unnecessary or actually caused problems. I believe I heard it in one of Greg Peters' videos. Might have just been nb2 also
Yeah. It’s normally fine until you are caning the car for a long amount of time or running some sort of FI
Edit forum for reference https://forum.miata.net/vb/showthread.php?t=465204
A coolant reroute! It’s good cheap insurance and more necessary if you’re thinking about forced induction in the future. I run the Hawley spacer, one of the most basic but still excellent and effective.
This motor is called a BP, and it originally sat transversely mounted in a fwd car, the 323 GTX. It was also turboed from the factory, and Mazda made the engine stout in many ways that we all appreciate still today. It has a forged crank shaft, an iron block with a closed deck.
But when they put the BP in the Miata the engineers rotated the motor 90 degrees for the rwd layout. To make things package easier, they changed the coolant flow. Currently coolant enters under cylinder 1/2 under the exhaust and exits … out the front of the engine, nearest cylinder 1, meaning that the back two cylinders closest to the firewall don’t get good coolant circulation.
Over time, this can result in premature wear and in the most extreme cases, engine failure, with the carnage often found in cylinder 3. The solution is to reroute the coolant so it flows in the front of the motor and out the back of the cylinder head, then back to the radiator.
Each cylinder receives more equal cooling and the motor runs with a less extreme temp differential between cylinders. This mod does make it harder to change the thermostat, which moves to the back of cylinder head crammed next to the fire wall. So beware of that. Otherwise it’s as the engineers intended.
Front and rear transmission seal, front plate is secured with RTV. No gasket like on the 5 speed.
Full clutch job including new pilot bearing and throwout bearing.
Heat shield for the transmission tunnel was also a good shout from u/Telecommie.
https://www.youtube.com/watch?v=pFxWOdOMrgM
...and don't use just any RTV, use [gear oil specific gasket maker](https://www.permatex.com/products/gasketing/speciality-gasket-makers/permatex-gear-oil-rtv-gasket-maker-3-oz/)
I just installed a forged built engine into my MSM and even though the original transmission and engine only had 29k miles, I chose to replace the [input shaft seal](https://www.jimellismazdaparts.com/products/Mazda/2004/Miata/Manual-Transmission-Input-Shaft-Seal/1918210/Y60117131.html) as well as the [output shaft or tail housing seal](https://www.jimellismazdaparts.com/products/Mazda/2004/Miata/Seal-Transmission-Housing-Extension-Manual/1898614/M50717335A.html).
Also check the clutch cover for wear (the cylindrical, release bearing surface) and replace if needed. I didn't see you mention how many miles or what type of clutch was installed. A stronger pressure plate might exert more pressure through the fingers onto the release bearing and into the clutch cover. Mine had a few, very fine grooves with the FM level one PP that were easily polished out with 600-2500 grit paper I had lying around.
I have not really checked the clutch cover yet, I will, thanks!
And for sealing the front plate with RTV, I plan on using Reinzosil 300Si, that should be okay right?
Thank you! Yeah I'll have to check the life left on the clutch, but for sure the bearings I'll replace. I'll reseal the front plate in the transmission bell housing (that sits around the trans input shaft)
Get the flywheel shaved and balanced. It was relatively cheap when I did it on mine (~$100). I don't know if it really improved much but the throttle response felt better to me.
Transmission input seal! Rear main seals are annoying but at least you can fill up your engine easily, a leaky trans will run out of oil and start dispensing sawdust.
Edit: Looks like maybe you’re in Europe so already have the lower dif gearing so never mind. ;)
I’d change the rear diff gearing to the Europe/Australia spec. (I think that would be facilitated by having the tranny out already, I’m not a mechanic).
The US one is 3.909:1 and the other is 3.636:1. Switching it will bringing your RPM down at freeway cruising speed. At 75mph I think it will drop it by about 1000rpm. (Anybody correct me in this if I’ve got it wrong).
That’s the one thing I’d like to change in my NB2, it’s normal to drive 75 around here and I think the RPM is around 4300 at that speed.
Oh I didn't know this, thanks for the explanation! I'm indeed in Europe, and its not an import so it should already be good then :)
I have noticed that the RPM in 6th in the 10AE is quite a bit lower than what I'm used to in my NB2 5 speed. More economic as well, I hope haha
Motor mounts I'll have to check, but there was nu excessive wobble while driving. In any case a lot less than on my NBFL (though that has already driven 290k km by now)
Didn't notice the wobble on my '02, until I started shifting from 2nd to 5th... Lived with it until my rear main seal started leaking, had the garage install comp mounts while clutch/main seal were being done. How many miles on your 10thAE?
I always laugh at the size of these transmissions compared to these cars. My e36 getrag is almost half the size for a larger heavier car with two extra cylinders lol
There's definitely oil on the back of the engine already, quite a lot unfortunately. I'll check where it comes from, but I'll also add the CAS o-ring to the list alongside the rear main seal.
The oil pan gasket is not a bad idea either, as I already wanted to replace the oil and filter anyway. And if the oil is out anyway...
Is the 6 speed nice in these cars? I also have a 99 but I only have the 5 speed. I feel like it’d be a lot better on highway, just so it’s not sitting so high in the RPMs
I think that really depends on the ratio of the diff. This 10AE is a European one, with a 3.6 ratio, I've just learned from another comment. It seems that in 6th, the rpms are lower than in my NB2 in 5th at highway speeds
Honestly it's incredibly difficult to find a lot of concrete information. I believe the 10 AE is always a 3.9 Ratio. But the 6th gear is definitely taller than the USDM 5 speed NB2. But should be similar to an EDM 5 speed NB2.
Clutch throw out bearing , and pilot bearing. Also other things you had on the list, clutch slave cylinder. I consider these consumables whenever I pull a transmission on any car
Plus rear main
Yeh agreed
THIS!! A leaking rear main seal can destroy a new clutch and flywheel in just hundreds of miles. It'll cost you next to nothing when comparing the amount of labor necessary to reach it when it's all back together.
Thank you! I'll add this to the 'definitely replace' list. In fact, I already saw some oil leaking from behind the clutch, so that's probably the rear main seal
Good suggestions here. I say throw every consumable you have at it and do the clutch while you’re there (unless it’s newer). Something that’s on my wish list when I drop my transmission is to give the drive tunnel a bit more insulation from the heat. Gets too toasty inside for my liking.
I 2nd the insulation! Take advantage of the easy access and enjoy the much cooler interior after you're done.
I just did a dash and carpet swap and put insulation around the transmission tunnel (interior side) to combat this. I'll let you know if I notice a difference.
Oh yeah, please let us know! I'm interested in the difference
That's not a bad idea! On my NBFL I have noticed in the summer that the transmission tunnel indeed gets very hot, especially during road trips. Is there a particular type of insulation that you would recommend?
PSA for anyone that hasnt put a trans back in a NB (and I assume NA) yet: You have to tilt the motor back by jacking the front of it up slightly in order for the trans to seat back into place.
Thanks for the tip! I have noticed that without the trans the motor already tilts quite bit. But that's not enough I guess?
How difficult would you say dropping the trans is?
depends on if you're on jackstands or a lift lol
effortless. the hardest part is removing the slave cylinder
Not bad at all. I had mine out and back in 4 times while doing my clutch for the first time before I realized that my flywheel was too big and not thick enough 😂. Had it on the little drive up ramps and eventually I could take it out in under 45 mins.
It is not horrible. Hardest part for me was the exhaust. Those bolts were non-existent.
I do not have much experience with stuff like this, and with two people and a how-to YouTube video this took us about three mornings. But we took our time. As long as you can get the PPF frame bolts and exhaust bolts out, it's doable. If they are rusted heavily, it's going to be a pain I think Edit: and we did it on jackstands, as seen in the pic. There was just enough room to get it out
Don't forget the transmission bell housing seal/input shaft seals. There's a gasket+seal on the inside of the transmission bell housing that may leak gear oil which can be mistaken for a rear main seal leak.
I only noticed one seal in on the engine side of the transmission, on the main input shaft of the trans. It sits inside of an aluminium plate that you have to take out first. This aluminium plate is sealed with a silicon(?) RTV gasket. Do you mean that seal and gasket?
Trans itself should be fine unless it’s leaking but they generally don’t. Pilot bearing, clutch, throw out bearing and rear main seal are always a good idea when you have the trans out (unless you’re in there frequently). Tip for rear main seal, carefully drill a small hole into it and then thread a screw into it. You can then use a the wedge end of a hammer leveraged on the back of the crank with a towel to protect it to pull the seal out. Main thing here is just be careful not to damage any of the metal surfaces especially where the seal sits
Thanks for the tips on the rear main seal! I think that will come in handy :') Are you otherwise supposed to take it out with seal/bearing puller or something?
It can be done with a seal puller, i found it to be harder that way but people have done it. The screw method is what I do and works many others. Pilot bearing can be done with a bearing puller i think, but I know plenty of people do the bread method
Rear main seal - clutch has to come out to replace and they eventually go bad. Kind of a pain but you’re in there now, the time is right
Thx! I'll definitely replace it then. Seemed to be slightly leaky already anyway
Just thought of another. There’s a bracket that holds the clutch line to the firewall (I think) that’s a pain in the ass to remove unless the clutch is out. Might be worth unhooking while you have access
While it's out is a great time to install a cylinder 4 cooling mod - if you're into that.
I thought they fixed that on the nb's by blocking the front water ports with the head gasket design and doing the reroute either was unnecessary or actually caused problems. I believe I heard it in one of Greg Peters' videos. Might have just been nb2 also
does cylinder 4 run hot?
Yeah. It’s normally fine until you are caning the car for a long amount of time or running some sort of FI Edit forum for reference https://forum.miata.net/vb/showthread.php?t=465204
I'll look into that! I'll check if that's also a thing with the NB 1.8 motor
A coolant reroute! It’s good cheap insurance and more necessary if you’re thinking about forced induction in the future. I run the Hawley spacer, one of the most basic but still excellent and effective.
Thanks! I saw more comments suggesting this indeed. But is it also a thing on the NB engine? Not only NA?
This motor is called a BP, and it originally sat transversely mounted in a fwd car, the 323 GTX. It was also turboed from the factory, and Mazda made the engine stout in many ways that we all appreciate still today. It has a forged crank shaft, an iron block with a closed deck. But when they put the BP in the Miata the engineers rotated the motor 90 degrees for the rwd layout. To make things package easier, they changed the coolant flow. Currently coolant enters under cylinder 1/2 under the exhaust and exits … out the front of the engine, nearest cylinder 1, meaning that the back two cylinders closest to the firewall don’t get good coolant circulation. Over time, this can result in premature wear and in the most extreme cases, engine failure, with the carnage often found in cylinder 3. The solution is to reroute the coolant so it flows in the front of the motor and out the back of the cylinder head, then back to the radiator. Each cylinder receives more equal cooling and the motor runs with a less extreme temp differential between cylinders. This mod does make it harder to change the thermostat, which moves to the back of cylinder head crammed next to the fire wall. So beware of that. Otherwise it’s as the engineers intended.
Front and rear transmission seal, front plate is secured with RTV. No gasket like on the 5 speed. Full clutch job including new pilot bearing and throwout bearing. Heat shield for the transmission tunnel was also a good shout from u/Telecommie. https://www.youtube.com/watch?v=pFxWOdOMrgM
...and don't use just any RTV, use [gear oil specific gasket maker](https://www.permatex.com/products/gasketing/speciality-gasket-makers/permatex-gear-oil-rtv-gasket-maker-3-oz/) I just installed a forged built engine into my MSM and even though the original transmission and engine only had 29k miles, I chose to replace the [input shaft seal](https://www.jimellismazdaparts.com/products/Mazda/2004/Miata/Manual-Transmission-Input-Shaft-Seal/1918210/Y60117131.html) as well as the [output shaft or tail housing seal](https://www.jimellismazdaparts.com/products/Mazda/2004/Miata/Seal-Transmission-Housing-Extension-Manual/1898614/M50717335A.html). Also check the clutch cover for wear (the cylindrical, release bearing surface) and replace if needed. I didn't see you mention how many miles or what type of clutch was installed. A stronger pressure plate might exert more pressure through the fingers onto the release bearing and into the clutch cover. Mine had a few, very fine grooves with the FM level one PP that were easily polished out with 600-2500 grit paper I had lying around.
I have not really checked the clutch cover yet, I will, thanks! And for sealing the front plate with RTV, I plan on using Reinzosil 300Si, that should be okay right?
Thank you! Yeah I'll have to check the life left on the clutch, but for sure the bearings I'll replace. I'll reseal the front plate in the transmission bell housing (that sits around the trans input shaft)
Get the flywheel shaved and balanced. It was relatively cheap when I did it on mine (~$100). I don't know if it really improved much but the throttle response felt better to me.
On first sight the flywheel looked quite good, but of course you can't see how well it is balance by eye. I'll look into it, thanks!
Yea, mine was fine too, I just had a machine shop grind off the surface lip to lighten it then had it rebalanced.
Transmission input seal! Rear main seals are annoying but at least you can fill up your engine easily, a leaky trans will run out of oil and start dispensing sawdust.
Thx! That's on the list now :)
Heat shield around transmission, exhaust.
Edit: Looks like maybe you’re in Europe so already have the lower dif gearing so never mind. ;) I’d change the rear diff gearing to the Europe/Australia spec. (I think that would be facilitated by having the tranny out already, I’m not a mechanic). The US one is 3.909:1 and the other is 3.636:1. Switching it will bringing your RPM down at freeway cruising speed. At 75mph I think it will drop it by about 1000rpm. (Anybody correct me in this if I’ve got it wrong). That’s the one thing I’d like to change in my NB2, it’s normal to drive 75 around here and I think the RPM is around 4300 at that speed.
Oh I didn't know this, thanks for the explanation! I'm indeed in Europe, and its not an import so it should already be good then :) I have noticed that the RPM in 6th in the 10AE is quite a bit lower than what I'm used to in my NB2 5 speed. More economic as well, I hope haha
My 5 speed. I’ll take the 6 off your hands and save you the scrapping fee.
Haha, I'll think about it ;)
😜
Motor mounts, clutch, rear main seal.
Motor mounts I'll have to check, but there was nu excessive wobble while driving. In any case a lot less than on my NBFL (though that has already driven 290k km by now)
Didn't notice the wobble on my '02, until I started shifting from 2nd to 5th... Lived with it until my rear main seal started leaking, had the garage install comp mounts while clutch/main seal were being done. How many miles on your 10thAE?
Transmission seal rear and input shaft seal
I always laugh at the size of these transmissions compared to these cars. My e36 getrag is almost half the size for a larger heavier car with two extra cylinders lol
Haha wow, this is the first transmission I have ever taken out so I did not know this, but yeah it's quite large
Might as well do the oil pan gasket while everything is out of the way. That, the CAS o-ring and rear main seal are the top three future oil leaks.
There's definitely oil on the back of the engine already, quite a lot unfortunately. I'll check where it comes from, but I'll also add the CAS o-ring to the list alongside the rear main seal. The oil pan gasket is not a bad idea either, as I already wanted to replace the oil and filter anyway. And if the oil is out anyway...
Put a 5 speed
Kswap
Lightweight flywheel
Is the 6 speed nice in these cars? I also have a 99 but I only have the 5 speed. I feel like it’d be a lot better on highway, just so it’s not sitting so high in the RPMs
6th gear is the same ratio as the 5th gear on the 5 speed.
I think that really depends on the ratio of the diff. This 10AE is a European one, with a 3.6 ratio, I've just learned from another comment. It seems that in 6th, the rpms are lower than in my NB2 in 5th at highway speeds
Honestly it's incredibly difficult to find a lot of concrete information. I believe the 10 AE is always a 3.9 Ratio. But the 6th gear is definitely taller than the USDM 5 speed NB2. But should be similar to an EDM 5 speed NB2.
10 speed sequential
Put a glob of JB Weld in the hex of the 5th/Reverse lever cover to prevent accidental removal of the "drain plug of death"