Printable View
Attachment 7649 Attachment 7651 Attachment 7650
Apart from the IGN Coil Cover gasket, most of the gaskets will be installed into the covers at this stage to allow the liquid gasket to cure.
The two rubber seals each on the Front and Rear TB cover.
The very expensive single gasket on the TB Lower cover.
Two different gaskets and three round IGN Coil hole seals at the head/valve cover.
Attachment 7654 Attachment 7655
Attachment 7656 Attachment 7657
As expected, the water pump was never replaced in the past. It was still the original design and hence, the TB Lower cover was also the old design. Note the difference in the location of seeping hole at the lower cover as well as on the WP.
Attachment 7658
After removing the TB, it is very unlikely to happen but to be 100% sure not to move the camshaft accidentally while the crankshaft at #1 TDC, always lock the four camshaft with parallel pin punch or similar tool.
Attachment 7661 Attachment 7659 Attachment 7660
The water pump bearing showed small amount of rattle even for a short mileage so good to be replaced this time. Also, the TB tension adjuster bearing was showing tiny rattle.
Always replace this with the tension spring as well.
NSX doesn’t have auto tension mechanism and once you set it at the time of TB service, you are relying on it until the next service. The spring will be used as a part of tension adjust process so it is best to use new one.
More to follow.
Attachment 7665 Attachment 7669 Attachment 7666
Bit difficult to see in the photo but cleaning the red sealant residue at the WP bolt thread. Use good quality tap to remove as much sealant as possible but with great care.
The two dowel pins for the WP and the new OEM WP bolts with red sealant.
Attachment 7667 Attachment 7668
New latest WP installed and torque checked.
In order to double check the WP O-ring, carry out pressure/vacuum test on the coolant system again at this stage. You don’t want to find any WP related issues after you have finished the TB service.
Attachment 7670
While keeping the coolant system under pressure/vacuum for leakage test, prepare for the camshaft removal.
Attachment 7671 Attachment 7672Attachment 7673
Removing Front camshafts. There were some black residue at the oil passage of Front cam holder #2 & #3. Possibly the blow by and another reason for the importance of regular engine oil change especially if you drive NSX for a short distance regularly.
Attachment 7676 Attachment 7675
Don’t forget to replace the O-ring at the Oil Passage under the cam holder #1. There is one O-ring at each bank.
Attachment 7677 Attachment 7678
Both Front and Rear camshafts are now removed.
Time to clean the engine again to remove any liquid gasket residue around #1 and #4 cam holders.
More to follow.
Attachment 7685 Attachment 7686 Attachment 7687
Scrape off the old gasket thoroughly.
Front and Rear bank camshaft holders cleaned and inspected.
It is important to double check the tiny oil jet free from any debris.
Attachment 7688 Attachment 7689
Cleaning the camshaft.
While the camshafts are off the car, this is the last chance to clean the back plate and the rest of the area.
Attachment 7690 Attachment 7691 Attachment 7692
Cleaning the area around oil pump and crank shaft oil seal.
Prepare the cam seal and cap for the installation of camshaft.
It’s not the soy sauce. It’s the engine oil……
Attachment 7693 Attachment 7694
New O-ring installed at No.1 cam holder on each bank.
In the process of installing the Front Camshaft.
Attachment 7695
Applying torque to the bolts in the specific order in several turns using the digital torque wrench.
Very improtant process as this will affect the valve clearance adjustment later.
Attachment 7696 Attachment 7697 Attachment 7698
Front camshaft installed.
Rear camshaft installed.
TB installed.
Attachment 7699
Now, one of the most important process. The tensioning of TB.
There are several methods to carry this out but I prefer briefly installing the crank pulley and then lock it while applying force to four camshaft pulleys in specific order.
Attachment 7700 Attachment 7701 Attachment 7705
This NSX is AT so the crank pulley is different from the one for MT.
Final stage of adjusting the tension of TB by rotating the crank pulley until the blue mark meets the pointer on the TB Lower cover.
Attachment 7703
Torque the TB adjuster bolt to the spec and before you forget, install the O-ring/rubber seal over the TB tension adjuster bolt.
Quite often, I found this O-ring/rubber seal missing on UK based NSX.
Attachment 7704
The owner mentioned that he was experiecing some oil drip on the garage floor.
After cleaning the engine, I found some sealant used at one part of the oil pan area.
Normally, the oil leakage is from the oil pan gasket or from the head/valve cover area.
Looks like the person who worked on the oil pan gasket followed the specified torque figure on the Workshop manual.
That is way too much and one of the biggest reason for causing oil leakage.
Probably, it already de-formed the oil pan and requires replacement.
It requires removing the Front downpipe to remove the oil pan.
As I don't like removing it without having access to the spare O2 sensors, we will need to monitor whether the oil leakage was from the oil pan or from the head/valve cover area and select the appropriate measure next time.
Now it's time to take break before carrying out the valve clearance adjustment. Very delicate touch requried if you are carrying out this proess while the engine is on the car.
More to follow.
As always , excellent write up and photos Kaz, now that I am back in Bedfordshire, I'd like to see you about a health check/service for my car as it is LONG overdue.
Jim
Where are you based in Bucks? I'm also in Bucks.Quote:
Originally Posted by AR
There is quite a lot of work to be carried out on my car including air con, new front knuckles (worn ball joints!), replacement ABS modulator etc . . . not to mention window fix kit and other smaller items.
I had been planning for most of this work to be carried out at a local garage . . . well at least the larger work. However things like the Antennae still do not work properly so I would be very interested in your "check up".
Attachment 7719
Before starting the Valve clearance adjustment, just check the TB installation for the timing and tension again and again and again.
Attachment 7720 Attachment 7721
The combination of tools for the valve clearance adjustment.
Front Bank adjusted.
Attachment 7722
Rear Bank in the process.
Attachment 7723 Attachment 7724
Front bank checked for the clearance and torque twice.
Rear bank also checked twice.
Time to put everything back in place.
More to follow.
Excellent write-up and pic as usual Kaz :)
May I ask the reason why you removed the cams? Was there something going on/wrong that required it or was it purely for inspection purposes?
Cheers
Mark
Hi, Mark.
Nothing wrong with the engine and it's just the standard procedure included in my TB service.
The main purpose is to replace the camshaft oil seal (brown) and the cap (black) during the TB service as in post #448.
You may be able to replace the cap without completely removing the camshaft but you will need to replace the small O-ring under cam holder #1 and to replace the cam oil seal, you need to remove all four cam pulleys any way so best to take the camshafts out of the engine.
Also, I prefer cleaning the cam holders and covers and check the camshafts.
The oil jet is such a small diameter and I don’t want to leave them until the next TB service without being cleaned and compressed air passed through each of them. I don’t like blowby gas residue and we are relying on these tiny oil jet for the camshaft lubrication.
Kaz
Attachment 7725 Attachment 7726
TB Front cover and the Rear one installed.
Attachment 7727 Attachment 7728 Attachment 7729
New Figure of 8 O-ring for the oil cooler base and the assy installed.
Crank Pulley for AT model so the diameter is different as well as the appearance. The pulley bolt has been lubricated, cleaned, degreased for the specific area and torqued to the spec.
Attachment 7730
The side AT mount bolt torqued to the spec.
Attachment 7731 Attachment 7732 Attachment 7733
The head/valve cover was cleaned and prepared with the new gasket kit a few days ago so the liquid gasket has already cured.
Before the installation, the gasket thickness looks like this.
Then, after the installation, it will be squeezed down to this thin level so it is very important to always use the new and complete gasket kit once you open the head cover. Otherwise, it will cause oil leak.
Attachment 7738 Attachment 7734 Attachment 7735
New ACG and A/C belt. For AT, you need AT spec ACG belt.
ACG and Front head cover installed followed by the rear one.
Attachment 7736 Attachment 7737
Almost done for re-assembling the parts and ready for re-filling the coolant system and for another compression check.
Owner wanted to add extra service while the car was at my place.
He wanted to install the USA Spec PA11-Hon iPod adaptor.
I have been using the same supplier in US for many years and normally, I can get it in about a week after placing the order.
However, for this time, it was taking long time not even shipped out from US after about two weeks.
It was the problem at the manufacture sending re-conditioned or used products to my supplier and I’m glad they spotted it before sending it to UK.
In fact, the supplier had to return the products twice to USA Spec as they were not happy with the package. Another reason why I like keep using this supplier because of the attention to the detail.
It completely changed my future service and Health Check plan for other owners but I hope I can get it very soon….
More to follow.
Attachment 7739 Attachment 7740 Attachment 7741
The sticker included in the JDM Timing Belt kit. It will show the history for the TB service.
As mentioned previously, I didn’t like the corrosion at the original spark plugs even well below the 60K miles service interval. Therefore, all six plugs were replaced with the new ones.
Attachment 7742
One of the most important parts to be replaced. The IGN Coil cover seal. New one installed and applied silicone grease. Best to check it once a year.
Attachment 7746 Attachment 7743 Attachment 7747
Honda Type 2 Coolant.
For some reason, they keep changing the label…
Vacuum feed and start the engine for a short period to initially adjust the coolant level before completely warming up the engine.
Attachment 7745 Attachment 7744
Disable the INJ and set the throttle butterfly to WOT.
Then, time for the compression check after the TB service.
I always spend many hours adjusting the valve clearance. May be I’m aiming too much of the perfection of detail but it always paid off at the end.
The compression between each cyl is much closer than the data measured before starting the service.
Before: #1:**9, #2:**8, #3:**1, #4:**4, #5:**6, #6:**8
After : #1:**2, #2:**1, #3:**1, #4:**1, #5:**0, #6:**1
Wait for the engine to cool down before adjusting the coolant level again and time for the test driving session.
More to follow.
Attachment 7748 Attachment 7749
Installing the IGN coil.
The most important collar before placing the IGN Coil cover.
Attachment 7750 Attachment 7751 Attachment 7752
Front and Rear Bank completed.
Engine bay finished.
For TB service, it is not required to change the Eng Oil. However, for this NSX, it was decided to replace it at the same time. There was about 0.8L of excess oil inside the engine. For some reason, this is getting quite common for UK NSX. Also, I seem to encounter over torqued oil filter regularly these days. Oil level adjusted properly.
Attachment 7753
I wanted to monitor the condition of oil leakage as we replaced complete gasket kit during the TB service.
However, just looking at the state of Oil pan and pan gasket, it would be best to replace both of them in the future.
As mentioned previously, way too much torque was used in the past with strange looking trace of sealant at the oil pan. The gasket was over torqued so much that it was sticking out of its place and touching the oil filter. Best to get hold of spare front O2 sensor and take out the front down pipe/header to remove the oil pan.
Attachment 7754
The owner wanted to have his broken door light lens/cover repaired. The two of the locking tabs were broken and only one of them were recovered. Used the special plastic repair kit for the task.
I could have created the missing tab using the special moulding method but it would be cheaper to buy new one so decided to use this repaired one in the boot and use the original boot one into the door panel.
Test driven the car, placed it on the lift over night, adjusted the final coolant level, checked for any leakage and final check for completion of TB service.
More to follow.
Hi Kaz is it the case that JDM cars have a clear cover for the doors and UK cars have a Red one?
Cheers,
AR
Yeah, JDM cars have clear door lights Ary!Quote:
Originally Posted by AR
As this NSX has aftermarket suspension sets and larger wheel size, I used my own alignment setup last year. Based on this and recent temperature drop, I have set the tyre pressure at 31psi Front and 37psi Rear this time.
Normally, I will be using 30/36psi combination for this NSX.
Attachment 7755 Attachment 7756
The owner wanted me to investigate the brightness difference between the Right and Left tail lights.
This NSX is JDM so it uses different light setup and wattage.
After removing the bulbs, it was quite clear that the small 5W ones were both nearly at the end of their life and changed into silver/black shade inside the bulb glass.
One of the twin filaments bulb was using different wattage (28/5W) and also most of them were starting to show some black shade. After talking to the owner, it was decided to replace all bulbs.
JDM uses 27/5W for the tail brake/small lights whereas UK one uses 21/5W.
I was little concerned about using smaller wattage because of the feature of brake light failure sensors. However, as the face-lifted UK NSX is using exactly the same failure sensors as JDM one even for the 21/5W setup, I decided to go ahead and replaced all of the bulbs to the ones available in UK.
No issues so far.
New ones installed and checked.
Attachment 7757
The owner was experiencing squeaking noise from one of the speakers recently.
I refurbished the Bose Amplifiers last year so I offered the owner for free of charge replacement AMP if it was faulty.
However, initially, I couldn’t re-create the same issue on the car nor on the bench.
In order to save some time, I decided to install another spare AMP inside the Bose speaker box.
Finally, after 5Hrs of testing, it started to make some annoying noise from Right Door speaker even with the replacement AMP.
It was like someone using sandpaper back and forth on the plastic panel.
The noise was only from the right door speaker and it didn’t change the level even when the volume level was turned all the way down to zero.
The noise didn’t change by altering the input such as FM/AM/CD sequences.
The audio balance setup didn’t change the noise level.
Attachment 7758
In order to be 100% sure that it is not the AMP or Speaker issues, I decided to run my bench system with spare AMP and another Speaker unit connected to the actual door speaker connector.
As soon as it started to make the noise, I placed the original Bose speaker box from the right door and managed to re-create the same noise as the bench system one.
It confirmed that the noise was coming from either the headunit itself or from the wiring before entering the speaker box.
Attachment 7759 Attachment 7760
Attachment 7761 Attachment 7762
Based on the recent experience with another headunit, it may worth trying the similar service in the near future. It lost the power completely due to capacitor leakage and I also replaced several capacitors in order to remove the noise.
This NSX has been modified to have wider body work and during this process, the rod aerial was removed.
JDM headunit uses diversity aerial system so it has another aerial in the engine hatch glass.
However, there seems to be no frequency shifter/converter added to the FM input port on this NSX and thus, the owner couldn’t receive any radio stations.
Therefore, at the time of headunit service, it is best to add the frequency converter and add another aerial to make the diversity system to work properly.
Attachment 7763
Although it looks like we may have headunit issue, in order to install the iPod adaptor USA Spec PA-11 HON, I started to disassemble the interior panels.
Hope I can receive the parts from US very soon as it forced me to change some of the future service schedule for other owners.
Just need to check the state of DIY A/C filter that I installed last year, carry out the annual A/C blower motor fan and Evapo cleaning process plus annual Health Check Service and ready to return the car to the owner.
More to follow.
Kaz
Just about a year ago, I found lots of dirty/sticky debris on the A/C evaporator on this specific NSX and after cleaning it, I installed DIY made filter at the top of blower motor fan entrance.
Attachment 7764 Attachment 7765
After one year, looking at the debris trapped by the filter, it did great job in keeping the evaporator clean and resulting in not breathing these things while you are driving. Also, it will prevent the dust from sticking onto the cabin temperature sensor that may start making noise if it gets too dirty.
Initially, I didn’t understand the reason why the A/C smelled so bad even with fairly clean A/C evaporator fins.
Attachment 7766 Attachment 7767
However, after applying the UV ray inspection light, I found the cause of the issue.
It is very sad but unfortunately, it looks like the evaporator itself is leaking the A/C gas and oil.
A/C compressor oil attracts moisture and it is very sticky. Once it started leaking, it is quite nice place for the germs to breed resulting in bad smell.
Attachment 7768 Attachment 7769 Attachment 7770
I was hoping it was leaking from the expansion valve just in front of the evaporator but the more I looked at it, the more it looked to be the evaporator leakage.
Unfortunately, OEM evapo is not cheap and on top of this, it will be a big task as both seats and the entire forward section interior panels (dash board, etc) have to come out before removing the evapo box.
Attachment 7771
For now, the best we can do is to wash down the leakage and kill the germ as much as possible until we replace the evapo unit.
Loosing the A/C oil is not good for the compressor and eventually, it will start making grinding noise due to the lack of oil.
Then, it will cost more to replace the compressor, cleaning the debris inside the system pipes, etc so sooner is better to address any A/C problems.
Time for the annual Health Check service.
It helps both the owner and myself a lot as we can build up detailed history of the specific NSX and monitor the changes over the years on certain areas.
Finally, the iPod adaptor USA Spec PA-11 HON arrived at Heathrow airport.
Now the waiting game starts with the UK Customs...
I hope they will calculate the duty/tax quickly and release the package so that it can be delivered to my place.
And when I just thought everything will be on schedule, my home boiler broke down. Hope it will be fixed very soon as I want to wash this NSX and use at least mild soft water at the final stage. I don't like using normal tap water as I live in very hard water area.
Regards,
Kaz
Ough! Please do write-up when you take the dash out.
Attachment 7773 Attachment 7774
Disinfected the evapo as much as possible and put the battery case, spare tyre holder and so on back on the NSX.
By the way, during the TB service or duration of the entire services, the battery was kept on the conditioner to keep it healthy.
About 1 year ago when the owner brought this NSX for the Health Check, I mentioned to the owner that this battery was from Japan and it was manufactured in Feb/01. Now, it’s more than 9.5 years old so it would be best to replace it soon.
This battery is of old spec and the internal cell/plate could physically collapse when it gets too old and with vibration.
You can’t re-charge it once it happens and for some reason, it always seems to happen at the most inconvenient timing.
The price of Honda battery dropped dramatically over the years and even the AT model requires the larger capacity one, it is the same price as MT model and only at about GBP54+VAT from your local Honda dealer.
Attachment 7775
Although you can’t see it from outside, I prefer cleaning the parts before putting it back in place so cleaned the battery case.
Attachment 7776
Carried out the four hours Health Check session. My own check sheet with more than 150 points to look at.
There were some new items to be addressed soon as well as some of the low priority ones from last year.
Attachment 7777
For example, as mentioned last year, looking at the text on the fuel filter, it looked to be the original one. Although JDM doesn’t have time/age related service interval for the fuel filter, considering the usage and mileage of this NSX, it would be best to replace it at some point in the near future.
Attachment 7778
Addition to the evaporator, the A/C gas/oil was leaking from the Front Right condensor area. There is an O-ring inside there and the O-ring material has been treated for different A/C gas type. Replacing the O-ring at this specific connection point is quite challenging and quite often, you will need to replace the entire condensor and the pipe as the fitting would no longer make good sealing due to the corrosion.
Attachment 7779 Attachment 7780
The Front bank CAT was very close or touching the rear diffuser bracket. Depending on the temperature, it could cause some noise.
Both door power window were very slow on going up. There are lots of nice write up on this on the NSX Prime and even a customised parts available from one of the member.
One thing to be noted. Whenever you adjust the window alignment or replacing the upper door weatherstrip and/or the Front Sash, you must double check the version of Front Sash and Weatherstrip.
Honda revised the design of weatherstrip and the part no. was changed accordingly. It changed how the window glass sits/seals against the weatherstrip. The part no. for the original design was superseeded and you can only get the latest design these days.
Attachment 7781 Attachment 7782
The design of Front Sash was also changed as you can see in the photos above. Left one is the original and it has thicker and stiffer section than the revised one on the right. However, the part no. didn't change and it looks like the parts manufacture changed it without telling Honda.
Because of this, if you work on the door window to improve the speed and adjusted the alignement or replaced some of the above parts, you may get water leakage or wind noise if you don't know the parts combination and how the door glass should sit on the weatherstrip.
This is not even on the parts system or workshop manual and one of the special know-how.
Attachment 7788 Attachment 7789
As mentioned in the earlier post, the Oil pan and pan gasket must be replaced by removing the front bank exhaust/manifold down pipe.
Even after a short test driving session after TB service, I already noticed tiny leakage from the area where someone placed some sealant.
Long-long time ago, when I removed the down pipe for the same purpose, I managed to trigger the ECL for the front bank O2 sensor. You don’t need to remove the Front O2 sensor for the down pipe but it sits right next to the connection point where you need to remove very rusty three nuts to drop the down pipe.
I was very careful not to apply even a tiny bit of penetrating oil at the base of O2 sensor but still, managed to contaminate it. If it was my NSX, I would probably just drive the car for a while to burn it off but at that time, I had to replace the sensor for the owner.
Since then, may be I’m bit too cautious but prefer not to touch the down pipe without having the access to the spare O2 sensor. Luckily, for earlier models, spare O2 sensor is quite cheap so kind to our pocket.
I’ll need a few days to complete the Health Check report and then it will be forwarded to the owner.
Where is the iPod adaptor?? It’s still sitting at the UK Custom….. It is taking really long time for them to calculate the duty/tax. It was shipped out as Express service but already 3 days gone past… Is everyone already buying Christmas presents from abroad??
While waiting for the delivery, I decided to start modifying the centre arm rest using the existing holes.
Attachment 7790 Attachment 7791 Attachment 7792
During the process, I noticed that the arm rest lid didn’t close smoothly. I found that one of the spring at the hinge got dislocated and obstructing the mechanism. Disassembled the lid module and repaired the hinge. Now, it closes properly.
Attachment 7793 Attachment 7794 Attachment 7795
Drilling the hole at the base of the arm rest box to allow the iPod adaptor cable to pass through. Same thing on the thin aluminium plate at the bottom of the box.
Using the rubber grommet to prevent anything dropping through the gap once the cable is installed.
Now I really need the package to be delivered very soon as all other owners are queuing for the services… I haven’t even managed to contact any of the owners waiting for the Health Check for several months…
More to follow...
After sending email to Parcel Force, finally, the iPod adaptor USA Spec PA11-HON was released from the UK Customs and on its way to delivery depot.
I haven’t received the letter for paying the duty/tax/handling charge yet so it will take extra few days before delivery but just need to wait.
I may pick up the package by myself to speed up the process before the delivery.
Once this iPod adaptor is installed, there will be no power to the CD changer. Therefore, spoke with the owner and we decided to take out the CD changer. It’s quite easy if you have the installation manual for it.
Attachment 7798 Attachment 7799 Attachment 7800
The original unit. In the process of removing the bracket.
Attachment 7801 Attachment 7802
Removing the extension cable. CD changer and all the extra parts including the extension cable removed from the panel ready to be handed over to the owner.
For the preparation of next NSX service, started to re-furbish the Right side drive shaft using my precious spares. This will at least save some time to cope with the long delay.....
Attachment 7803 Attachment 7804 Attachment 7805
Painted the joints and shaft as usual.
Cleaned and inspected each rollers. There are 6 joints in total for each drive shaft.
Planting the 10’s of roller bearings with the new grease.
On my NSX, I noticed that the side sill panel rattles a little when pressed down.
Attachment 7806 Attachment 7807 Attachment 7808
Long time ago, I found several damaged brackets inside this panel which resulted in rattling noise so I used special plastic repair material to repair them.
However, due to the specific plastic material being used, it seemed that it didn't bond together well.
Attachment 7809 Attachment 7810
This time, I decided to use the anti-vibration glue to secure the brackets and replaced some of the side clips.
Will need to leave the side sill overnight for the glue to cure and then I can start putting back all the parts in their original place.
More to follow...
Attachment 7819
Once the glue settled, the side sill was placed back on my NSX.
No more rattling and I’m happy now.
Attachment 7820
Once the CD changer was removed, please remember to insert the three screws to protect the internal mechanism during transportation.
There is a small bag attached to the changer cable and if the instruction was followed properly during the installation process, you should find these screws inside this bag.
If someone wants to use this CD changer again, then he/she will need to remove these screws during the installation.
One of the screw is under the white label and once the screws are removed, the hole should be covered by small tape to avoid dust getting inside. Initially, there was small black tape included in the installation kit.
I couldn’t wait any longer for the delivery of iPod adaptor and although I haven’t received the letter for the Duty/VAT payment, Parcel Force was kind enough to check the total price and let me collect the package from their local depot.
For your reference, the iPod adaptor was about GBP100 including the delivery charge from US and GBP30.00 for the VAT including the handling charge for Parcel Force.
Attachment 7821
The USA Spec iPod adaptor PA11-HON.
Before starting the installation, I checked the adaptor on my NSX and it worked fine. Then, tried the same on this NSX and the head unit didn’t recognise the adaptor as the CD changer.
I had similar issue in the past so decided to open the head unit and found this.
Attachment 7822 Attachment 7823
Some of the capacitors were leaking the acid and damaging the circuit board. I think this is also the cause of the loud breaking/sand-paper-like noise at the right side door speaker even after the Bose AMP was replaced.
This head unit is JDM so the circuit board design is different from the European model including the UK spec. However, the symptom was exactly the same as the one that I recently serviced as in the post #467.
I was lucky enough to keep just 1 set of capacitors required for the head unit service as I normally don’t keep any stock for this.
Attachment 7824 Attachment 7825
Cleaned and repaired the dissolved circuit track.
Bench testing the head unit with Ext cable to simulate the length of the cable to the iPod adaptor.
iPod Mini correctly recognised and playing the 95th MP3 file. You can control the iPod through the control buttons on the head unit just like operating the CD changer so you can skip, fast forward/rewind, shuffle, etc. If you use the specific name on the ‘Play List’, you can also deal with several play lists by selecting the Disc number