* CLUTCH REPLACEMENT & REAR SEAL TIPS *

Dealing with all subsystems specific to the diesel powered Datsun-Nissan 720 pickup trucks.

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EvergreenSD
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Joined:14 years ago
Location:Eugene, OR

#16

Post by EvergreenSD » 14 years ago

Would Beck-Arnley be a good choice for a clutch kit? RockAuto has them for a decent price. Thanks for the tips. BTW, I do intend to have my flywheel surfaced and replace the rear main seal while I am at it.

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asavage
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#17

Post by asavage » 14 years ago

The SD22's rear main seal looks like it's a four-piece design (a bit more robust than a "rope seal" but not as nice as a full-circle lip seal) that would require removing the oil pan and rear main brg to replace.

You have the 1982 FSM? Page EM-22 shows a pretty decent picture of the RMS. See also the picture on EM-34.

Flywheel runout, after assembly, should be under .006" (page EM-33).
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

EvergreenSD
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Location:Eugene, OR

#18

Post by EvergreenSD » 14 years ago

Update:

This weekend I managed to remove the transmission and the old clutch. It looks to me like the clutch had been replaced relatively recently. It is a Valeo brand and does not appear very worn. I was not able to find the 'smoking gun' revealing why I was having release problems, though there is light surface rust on the input shaft which was my leading theory. The rust is much less severe than I was expecting but maybe enough to cause an intermittent problem. I think that this clutch should have had years more service in it except that the throwout lever boot was not replaced which allowed water in to spoil the fun.

I was able to get the flywheel bolts off without an impact wrench which pleased me because I don't have one. When I pulled the last bolt out I expected the flywheel to come right off but it didn't. I tried some light tapping and prying but no cigar. What am I missing here? What is the approved technique? I am also wondering if it will be necessary to have the flywheel machined given that it looks like it was done recently. There is a very slight ridge between the area where the clutch rides and where it doesn't but the friction surface is not grooved with only minor galling that emery paper would probably clear up. Am I being foolish? I was originally planning to have the flywheel done but it looks much better than I was expecting. Also what would you expect a shop to charge for this?

My other question is whether there is anything else I should be looking for while I am in there. The throwout lever looks fine to me and the old t/o bearing was not seized. Also, do you have any tips to help make the tranny replacement go smoothly? I know I'm not supposed to let the tranny hang on the clutch hub but I'm not sure how to be certain that it doesn't happen while wrestling that lump into position. I just really want this thing to work right when I get it back in.

Thanks very much for all your help and for being such a priceless resource.

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asavage
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#19

Post by asavage » 14 years ago

EvergreenSD wrote:. . . there is light surface rust on the input shaft which was my leading theory. The rust is much less severe than I was expecting but maybe enough to cause an intermittent problem. I think that this clutch should have had years more service in it except that the throwout lever boot was not replaced which allowed water in to spoil the fun.
Water entering via the missing fork boot wouldn't be the big concern: the splines should have a light coating (light) of grease. Not graphite, grease.

Light rust is enough. Worn splines can cause hangup too, I've had to replace one input shaft for that symptom (not a FS5W71). The disk should slide freely on the input shaft.
I was able to get the flywheel bolts off without an impact wrench which pleased me because I don't have one.
How will you apply enough torque (36 ft-lbs) to put the bolts back in? The tool to hold the flywheel is a KV101056S0, 1982 FSM pg EM-52 (for reference only) but the easiest method by far is to rent an impact wrench, if you don't want to buy one. I clean the bolts and holes and use Lock-Tite blue on the bolts. You've got to remove all traces of oil for Lock-Tite to be effective.
When I pulled the last bolt out I expected the flywheel to come right off but it didn't. I tried some light tapping and prying but no cigar.
Use a deadblow hammer on the facing edge (the side that the disk runs on) near the rim, with two bolts still installed but backed out several turns. You do not want that flywheel to fall on you when it comes off. If you don't have a deadblow hammer, use a hardwood block: hold it to the flywheel with one hand, swing hammer with the other -- assuming you have two hands, of course. Sometimes, considerable force is necessary to break the "bond" to the crankshaft.
. . . will be necessary to have the flywheel machined given that it looks like it was done recently.
Good shop practice is to surface it if there is any perceptible "ridge", or if the clutch release action wasn't perfectly smooth -- ie if any judder on release was evident. Resurface and check runout as above, with a dial indicator.
Also what would you expect a shop to charge for this?
Our shop across the street gets $29 to resurface a carry-in flywheel -- non-stepped and dowels already removed. I don't think either of those apply to the SD flywheel.

I always check runout after mounting the flywheel back up. I've run into bent cranks twice, and grit at the mounting surface once, tilting the flywheel.
I know I'm not supposed to let the tranny hang on the clutch hub but I'm not sure how to be certain that it doesn't happen while wrestling that lump into position.
Use an alignment tool to center the disk prior to cinching up the clutch cover bolts. Chances are, your clutch kit comes with a plastic alignment tool. If not, spring for the $15 alignment tool setup, you'll use it again someday.

The 720 trans has to be shoved backward up onto the rear crossmember before bringing it forward to mate to the engine. Practically, this means that the trans is very stable during the wrestling phase. You shouldn't get into a position where the weight of the trans is entirely on the input shaft, but always watch the bellhousing-to-engine faces spacing and try to keep them parallel. And never use bellhousing bolts to "draw in" the transmission: if you can't get the two faces together by hand, something's wrong.

Have you already faced down the pilot bearing removal task?
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

EvergreenSD
Posts:70
Joined:14 years ago
Location:Eugene, OR

#20

Post by EvergreenSD » 14 years ago

I managed to get the flywheel off today, thanks for the tips. I didn't see that there was a stud that it rides on so I couldn't understand why it wouldn't drop off :lol: I was also mistaken in my assesment of the flywheel, it is mostly smooth but has one pronounced groove. I will have it surfaced.
I intended to replace the rear main seal but given what i've seen I'm not sure that's possible. Can it be replaced with the engine in the truck? I have previously fiddled with an old Mazda diesel where the end of the crank is flush with the block and the seal can be replaced by pulling the flywheel. I was thinking to find a similar situation on the Datsun instead of the 'flange' (?) that the flywheel bolts to. I can't even see the seal on the SD. Am I going to have to learn to live with the slow oil drip I attribute to this seal? Thanks for all the help and support, I'm a little new to this stuff. It's nice to be able to ask the experts :wink:

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philip
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#21

Post by philip » 14 years ago

EvergreenSD wrote:SNIP
I intended to replace the rear main seal but given what i've seen I'm not sure that's possible. Can it be replaced with the engine in the truck? I have previously fiddled with an old Mazda diesel where the end of the crank is flush with the block and the seal can be replaced by pulling the flywheel. I was thinking to find a similar situation on the Datsun instead of the 'flange' (?) that the flywheel bolts to. I can't even see the seal on the SD.
SNIP
SD22 rear main bearing saddle without bearing and seal.
Image

Rear main bearing saddle WITH bearing and upper seal half installed.
Image

Image

The SD engines use a two piece rubber lip seal. One half fits snaps into a deep groove in the cylinder block just outboard of the bearing shell saddle. The other half snaps into a similar groove in the bearing cap.

You must remove the oil pan, remove the rear bearing cap, and most likely loosen the other two main bearing caps sufficient to allow the crankshaft to drop an 1/8" from the block in order to get the upper seal half out of the block.

I would leave it be if all you are getting is some wetness, short of drips on the pavement. BUT, be sure it is actually the seal that is leaking. You might have a loose pan, a pan gasket leak between the pan and the bearing cap, or oil having escaped from the road draft tube that has blown around to the rear seal area ... in which case, the remedy can be much less involved.

Note: If you have an SD25, the WHOLE block and crank is different, featuring a single piece seal in a holder that is separate from the rear main bearing cap and the flywheel mounting flange has been omitted.

Image
Last edited by philip 14 years ago, edited 5 times in total.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

EvergreenSD
Posts:70
Joined:14 years ago
Location:Eugene, OR

#22

Post by EvergreenSD » 14 years ago

Thanks so much for the very informative pictures. I guess the seal is one less thing I have to worry about for now. I mistakenly thought that I should replace the seal while I had the flywheel off. I do just have wetness along the bottom of the tranny by the drain hole in the 'bellhousing'. I have never experienced any clutch slippage and I did not see any trace of oil on any of the clutch components so I'm not too concerned.

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philip
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#23

Post by philip » 14 years ago

EvergreenSD wrote:Thanks so much for the very informative pictures. I guess the seal is one less thing I have to worry about for now. I mistakenly thought that I should replace the seal while I had the flywheel off. I do just have wetness along the bottom of the tranny by the drain hole in the 'bellhousing'. I have never experienced any clutch slippage and I did not see any trace of oil on any of the clutch components so I'm not too concerned.
Same as mine! :roll: But the road draft tube is supposed to drip on the ground. :roll:

Two pointers. There is special spline grease available for the friction disc/input shaft splines. If not Nissan, try a BMW car or motorcycle outlet. Apply thinly. Also, your clutch pressure plate reassembly will go much easier using the correct "clutch pilot tool" to center the friction disc before securing the pressure plate bolts. Check with a decent auto store like NAPA.
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

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asavage
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#24

Post by asavage » 14 years ago

philip wrote:The SD engines use a two piece rubber lip seal. One half fits snaps into a deep groove in the cylinder block just outboard of the bearing shell saddle. The other half snaps into a similar groove in the bearing cap.
1982 FSM Page EM-22 shows a pretty decent picture of the RMS. It also mentions "Rear side oil seal" and shows four pieces total.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

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philip
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Location:Southern California, USA

#25

Post by philip » 14 years ago

asavage wrote:
philip wrote:The SD engines use a two piece rubber lip seal. One half fits snaps into a deep groove in the cylinder block just outboard of the bearing shell saddle. The other half snaps into a similar groove in the bearing cap.
1982 FSM Page EM-22 shows a pretty decent picture of the RMS. It also mentions "Rear side oil seal" and shows four pieces total.
In the aggregate, I have to agree. :wink:

The crankshaft seal is TWO pieces, per EM35 (SEM092)

The main bearing cap side packing is TWO different pieces, per EM36 (SEM061)
-Philip
Passed 08May2008
My friend, you are missed . . .

1982 Datsun 720KC SD-22

"Im slow and I'm ahead of you"

EvergreenSD
Posts:70
Joined:14 years ago
Location:Eugene, OR

#26

Post by EvergreenSD » 14 years ago

As I progress, more newbie questions emerge. I managed to extract the pilot bushing without difficulty by packing the area with grease and using a 5/8" wooden dowel with a couple of turns of masking tape around it as a plunger to force the grease behind the bushing. It took a bit of persistence but worked real slick. Installing the new bushing was harder than I expected given the looseness of the bushing I had removed. I tapped it flush to the flywheel drive flange with an oak block and a hammer.

How far into the hole should the bushing be seated? The old one was recessed a bit into the hole but the new bushing is quite tight and I don't want to over do it.

My other question is how I should go about removing and reinstalling the throwout bearing from the hub? I'm thinking I will need the right size puller to remove it and hoping a wood block will be enough to install the new ones. Thank you for all the sage advice.

BTW I found that the vapor seperator was leaking where it mates with the block and was probably supplying the oil I attributed to the rear main.

EvergreenSD
Posts:70
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Location:Eugene, OR

#27

Post by EvergreenSD » 14 years ago

I just wanted to post an update now that this job is completed. The clutch works great!! I still have not driven very far but so far so good. The clutch is working absolutely as it should; smooth engagement, no funny noises, and smooth shifts every time. Thank you so much for your help. I also adjusted the torsion bars and now the ride has improved as much as the clutch. The passenger side was riding about 3/4" lower than the other side which explains the pull to the left. Both sides were too low also which had caused uneven tire wear. The ride over bumps and the steering effort have also improved.

Next on the list is to repair the rust holes in the floor and install the Acura Integra seats I just found for cheap (thanks Craigslist). I'm still in the mock-up stage with the seats but they are very compact and supportive and the sliders have a tremedous range. In my kingcab they can go from scrunched up against the dash to so far back that I can stretch my legs out all the way without touching the firewall. They are going to be a huge improvement over the lamentable stock seats.

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asavage
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#28

Post by asavage » 14 years ago

asavage wrote:What I'm getting at is that the clutch fork boot is likely still available, likely pretty cheap, but may involve calling more than one dealer, and if you can get one of them to actually give you the part number, you can order it online yourself.
If I'm kicking the Parts Lookup correctly, the clutch fork boot is part No. 30542-E9000, $5.

I am not at all confident of that part number, though.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

EvergreenSD
Posts:70
Joined:14 years ago
Location:Eugene, OR

#29

Post by EvergreenSD » 14 years ago

I was able to get the boot from the dealer. I'm not sure of the part number but I think I paid about $8-10.

BTW- I bit the bullet and sprung for the AMSoil synthetic gear oil for the transmission and differential.

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asavage
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#30

Post by asavage » 14 years ago

If you can, try to find the part number. I'd like to cross-check my lookup. No biggee if you can't.
Regards,
Al S.

1982 Maxima diesel wagon, 2nd & 4th owner, 165k miles, rusty & burgundy/grey. Purchased 1996, SOLD 16Feb10
1983 Maxima diesel wagon, 199k miles, rusty, light yellow/light brown. SOLD 14Jul07
1981 720 SD22 (scrapped 04Sep07)
1983 Sentra CD17, 255k, bought 06Jul08, gave it away 22Jun10.

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