inline6 Posted August 18, 2013 Share Posted August 18, 2013 (edited) I rebuilt my late model 280ZX transmission a few years back. But, even with a new rear seal, I had a slight leak there. I don't recall if it was there before I rebuilt the trans or only after... I've driven the car rarely in the last several years, primarily a couple of track events, so the slight leak coming from the rear transmission seal was an annoyance, but not something I had to deal with on a daily basis. At first, I thought I damaged the new seal I put in when I rebuilt the transmission. But, I replaced that with another new one (which seemed to help briefly) but I noticed after the next track event, I still had some leakage. I began to suspect that my driveshaft yoke was too small in diameter. I bought it many years ago from Inland Empire Driveline. Even though I never had an issue in running it for years, I thought maybe it was machined to like the smaller end of acceptable tolerance range, and maybe it had worn some over the years, allowing fluid to start leaking. With the car back on the road recently I noticed that after every drive, it was leaking noticeably. I decided to devote some time to finding the issue. I pulled the driveshaft out to measure the OD of the yoke and compare that to a spare factory driveshaft yoke. I measured both with calipers and was surprised to see that they were the same measurement. Ruling out an undersized yoke as the problem, I re-installed the driveshaft and pushed upwards on the driveshaft yoke. I could see noticeable deflection in that direction and it appeared that the oil seal lip came out of contact with the OD of the yoke tube. Pulling down, I could see a rather large amount of deflection as well. I have a spare FS5W71B, so I pulled the rear seal and looked at what was behind. Here are a couple of pics: There is a sleeve which is press fit into the tail section of the transmission case. This one is showing some wear, but I suspect the one that is in the car right now is much worse. I'm guessing that with the amount of movement the transmission output shaft/driveshaft yoke is being allowed, it not only allows the seal lips to come out of contact with the yoke tube, but I am eating up rear main seals quicker... With these transmissions (of this vintage) likely to have lots of miles on them at this point, I wanted to make everyone aware of what I found. Also, anyone have any ideas for best way to repair? I can't find the sleeve on the microfiche... It doesn't look to be a part I can buy new from Nissan. Garrett Edited August 18, 2013 by inline6 Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 18, 2013 Share Posted August 18, 2013 I have this problem with my current transmission and the one I had in the car before. The bottom of my car is soaked in tranny fluid. The metal lining is very soft. It is possible to remove the sleeve, but I've never been able to find a new replacement. Perhaps there's a more compliant seal that could be used? Nigel Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 19, 2013 Author Share Posted August 19, 2013 I found this today. http://www.manualtransmissionpart.com/FS5W71-Bushings-Washers.html I placed an order for one, I'll report back when it comes in whether it is the right part. Quote Link to comment Share on other sites More sharing options...
Xnke Posted August 19, 2013 Share Posted August 19, 2013 They can be had from transmission shops, I got a few of them from Cobra Transmission in Florida. They are available, and are a soft sleeve bushing that can and should be replaced when worn out. Quote Link to comment Share on other sites More sharing options...
duragg Posted August 19, 2013 Share Posted August 19, 2013 (edited) More likely the 2 seals inside the shifter thing. They leak down and look exactly like the rear seal. There is one o-ring and one Lip seal. You have to pull the extension, remove the shifter mechanism, bang out the rear cap, pull out the long rod and then push out and replace the lip seal. Then bang / stake the rear cover which I gooped also. Then the external o-ring. Put it all back together (Again) and you should be fine. My experience... Edit: I think is is 32850H and 32710N http://www.nissanpartszone.com/Page_Product/PartDetail.aspx?ModelName=280ZX&ModelYear=1983&ModelSeries=S130&FileType=268&SelectConditions=%284%3dMT%3b5%3dF5%3b%29&ShowConditions=%284%3dMT%3b5%3dF5%3b%29&seeDesc=False&goBack=True&SectionNo=&ComponentsNo=328 Edited August 19, 2013 by duragg Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 19, 2013 Author Share Posted August 19, 2013 More likely the 2 seals inside the shifter thing. They leak down and look exactly like the rear seal. There is one o-ring and one Lip seal. You have to pull the extension, remove the shifter mechanism, bang out the rear cap, pull out the long rod and then push out and replace the lip seal. Then bang / stake the rear cover which I gooped also. Then the external o-ring. Put it all back together (Again) and you should be fine. My experience... Oh, right. I actually thought at one point along the way that either or both of those were the issue. When I started looking into the problem seriously (a few of months ago now) I did replace those first (the seal and the o-ring on the shift shaft) but I still have the leak. The shifter shaft and top of tail housing is dry - in this case, the fluid is coming out of the rear seal location for sure. The deflection of the driveshaft which appears to visibly allow a separation of the yoke tube to the oil seal lip is my primary indicator at this point. Garrett Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 19, 2013 Author Share Posted August 19, 2013 They can be had from transmission shops, I got a few of them from Cobra Transmission in Florida. They are available, and are a soft sleeve bushing that can and should be replaced when worn out. Is this the part you are speaking of? The picture is different than the factory... No cut outs or flutes for transmission oil to lube the yoke. Were the ones you got like the part pictured, and if so, how have they worked for you? Quote Link to comment Share on other sites More sharing options...
Xnke Posted August 21, 2013 Share Posted August 21, 2013 Yep, that's the one. They do have cutouts in them for the oil; and are fed via the aquaduct in the tailshaft housing that is in turn fed by the oil funnel that catches the slingoff from the 1st gearset. Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 21, 2013 Share Posted August 21, 2013 Yep, that's the one. They do have cutouts in them for the oil; and are fed via the aquaduct in the tailshaft housing that is in turn fed by the oil funnel that catches the slingoff from the 1st gearset. Thanks for the lead. I've got a couple on order now. Nigel Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 22, 2013 Author Share Posted August 22, 2013 Here is the one I got. It appears to be the right OD and ID, but it is 1/8th of an inch shorter than stock. And it only has cutouts/flutes on one side of it. Xnke, were the one's you sourced like mine? Also, stock length or a little shorter? And, mine was $14 plus shipping... instead of what... $3 from Cobra? Garrett Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 22, 2013 Share Posted August 22, 2013 (edited) I doubt 1/8" is going to make much difference, and oil is only fed from one side anyway. Based on the picture of what I ordered, the Cobra Transmission bushing only has one hole as well. But, it doesn't appear to have the channels like yours or the OEM piece does. Edit: I just noticed that the channels are not all the way around the inner surface on yours. It was only $4 though. Edited August 22, 2013 by Nigel Quote Link to comment Share on other sites More sharing options...
Xnke Posted August 22, 2013 Share Posted August 22, 2013 That's a 4-cylinder bushing, and it's a little shorter but as long as you line up the oiling hole, it's no big deal. That's what I used. The 6-cylinder FS5W71C has a slightly longer bushing, apparently, but I haven't found a place to get them other than Nissan. They are available, but I don't have the part number off the top of my head. Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 22, 2013 Author Share Posted August 22, 2013 That's a 4-cylinder bushing, and it's a little shorter but as long as you line up the oiling hole, it's no big deal. That's what I used. The 6-cylinder FS5W71C has a slightly longer bushing, apparently, but I haven't found a place to get them other than Nissan. They are available, but I don't have the part number off the top of my head. Hmmm. Interesting. Yeah, I looked all over the internet and couldn't find a part number listing for a FS5W71B. But, I wish I hadn't paid $14 for mine (I actually bought two), before I knew about the $4 ones. G Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 24, 2013 Author Share Posted August 24, 2013 (edited) I took the rear housing off of the trans and pressed the old bushing out. Upon close examination, it isn't bad at all. In fact, the ID on it is tighter than the new one. I used some 2500 grit sandpaper to clean it up a tad. It actually fits more tightly on the yoke sleeve than the new ones. Since it is longer, and obviously in ok condition, I put it back in instead of the new one. Now, I am back to square one. I don't know why I have this rear oil seal leak. Was it my imagination that I saw lots of deflection when pushing on the yoke of the driveshaft while it was in the car? The bushing obviously limits deflection... The stock driveshaft yoke sleeve measures 1.475 OD. The Inland Impire Driveline yoke sleeve measures 1.476 OD. The new bushing measures 1.482 ID... The stock bushing is probably a few thousandths smaller ID... I dunno. The main shift rod, that I replaced the o-ring and little oil seal on before, is perfectly dry. Absolutely no leakage there. I took the rear oil seal from the spare transmission and slid it onto the yoke sleeve. It actually fits a bit tighter than the relatively new oil seal that was on the trans in the car. So, I'll throw that one away and buy another new one from Nissan. But, I've replaced that with a new OEM one before... and still had the leak. I suspect another new one won't change anything. Pretty stumped. I hate fluid leaks. Edited August 25, 2013 by inline6 Quote Link to comment Share on other sites More sharing options...
duragg Posted August 25, 2013 Share Posted August 25, 2013 (edited) Great thread. Keep after it. Just be open minded that oil plus airflow can blow anywhere it wants. Triple check the stupid and obvious like drain and fill plugs and all fittings Edited August 25, 2013 by duragg Quote Link to comment Share on other sites More sharing options...
Xnke Posted August 25, 2013 Share Posted August 25, 2013 Check that your mainshaft assembly is still nice and tight...could be that the tailshaft bearing is worn out or the rear case is broken internally. (The ball bearing right behind the mainshaft nut, but way infront of the tailshaft spline.) Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 25, 2013 Share Posted August 25, 2013 Atlas 6" Lathe and some brass / oilite stock... Quote Link to comment Share on other sites More sharing options...
beermanpete Posted August 25, 2013 Share Posted August 25, 2013 Duragg makes a good point. Check the trans vent at the top of the tailshaft. If it is blocked the heat expansion of the air will casue oil leaks. Also, check the bore for the oil seal, perhaps if has a gouge in it from changing the seal that is causing the leak. Quote Link to comment Share on other sites More sharing options...
inline6 Posted August 26, 2013 Author Share Posted August 26, 2013 Duragg makes a good point. Check the trans vent at the top of the tailshaft. If it is blocked the heat expansion of the air will casue oil leaks. Also, check the bore for the oil seal, perhaps if has a gouge in it from changing the seal that is causing the leak. Thanks for the input. Very good sucking sound coming from the top of the trans when I drained the oil to remove the rear extension. Oil came out very smoothly. So, air vent is open. Inspected the periphery of the oil seal machined cut-out. A couple of very minor nicks, but otherwise looks good. Must be something else. Quote Link to comment Share on other sites More sharing options...
inline6 Posted December 1, 2013 Author Share Posted December 1, 2013 (edited) Working on transmission a bit while my engine is back at the engine builder. It appears I have another transmission leakage issue. What I thought was oil leaking out the of the back of the engine (I thought past the rear main side seals) is almost certainly transmission fluid. This means I have leaks coming from both the back and now, the front transmission seals. The thought occurred to me... I am currently running Redline MT90 transmission fluid. This stuff certainly seems "thinner" than what I've typically run in the past. Is it too thin? One other issue is I may have the front transmission seal installed backwards. I tried looking at the 280ZX workshop manual to determine, but I wasn't able to tell conclusively. I see 2 shiny rings around the mainshaft where the seal rides... so this is confirming to me that the part of the seal that touches the mainshaft is in a different spot than some time prior. Here is a pic showing the front seal installed with a new front seal just sitting off to the side - reversed from the one installed. Not sure why it would be leaking though as it looks to me like the seal is still riding on a spot on the mainshaft that looks like it would work. That said, I still think I need to pull it out and flip it around. Can anyone confirm? [edit] - yeah... it is in backwards. Clearly, the spring side of the seal isn't supposed to be facing the outside of the transmission where dirt and stuff can get to it. I am still not convinced that flipping it around will stop the leak though as the lip of the seal appears to be riding squarely on the mainshaft surface that it should be - it is just offset to near the edge of that surface. So, I wonder if the MT-90 is too "thin"? Edited December 1, 2013 by inline6 Quote Link to comment Share on other sites More sharing options...
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