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Shift rift

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Following up in the forum to a transmission issue I was having with my 4 speed. The issue came on fairly suddenly... I started to notice clanky shifts, especially 2-3 and 4-3, 3-2, 2-1. Also, one day while idling in gear with clutch in, waiting to pull out of a parking lot, it felt as though someone micro-rearended me... like maybe someone riding a Big Wheel, or tricycle, or someone on crutches... it was just a weird tiny lurch forward for a split second, and it had a 'metal' sound to it. So, I was a little worried it was synchro-related, and knowing that hard parts are getting more difficult to find, I started by contacting a few of you via PM about possible spares... just in case.

A PO had replaced master, I replaced slave about 2 years ago, so I felt confident it wasn't simply a clutch disengagement issue. However...

Something was missing... and apparently crunching around a lot

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Clutch media still had plenty of life left in it.  Pressure plate face was in great shape... just the grinding on the inside marked above, plus some uneven wear on the finger tips probably due to the spring bouncing around in there. 

Thanks to my declining ability to do real work, I had to find a shop to work on the truck... and they bent me over pretty hard for what turned out to be a simple clutch and pressure plate swap (parts are $83 at Rock). *sigh* I'm getting too old for cars that require maintenance.  But... it's fixed.

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Good update, I am glad its the clutch not the transmission.  That rebuild would be costly and time consuming to find gears and seals.

Keith

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Good update, I am glad its the clutch not the transmission.  That rebuild would be costly and time consuming to find gears and seals.

Keith

 

I really wish I had the energy to do a real solution to the transmission... grafting bellhousing to a newer 5 speed, like maybe a Type 9 (found mostly on Euro vehicles... it's smallish and light duty... no need for overbuilt parts behind a 67hp engine).  But, alas... changing the oil is about it for me these days.

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I am happy it is only a clutch and not the transmission.

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Mike outlined the work needed to change the bell housing on a later 71C (240SX) to the L-series one from the 71B.

A lot simpler than adapting a completely different trans.

You can find both in junk yards.

Don't know if your 4-speed bell housing will work.

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Don't know if your 4-speed bell housing will work.

4-speed bell housing is integrated into the rest of the case. It is not removable... except by violence. This bellhousing would be a required starting point since the L-series bell housing has a different bolt pattern as well. Or, build an adapter... but then have to resolve the 1" or so extra space it would force on the input shaft.

 

Grafting 2 together is really a simple and elegant solution... on paper. In reality, it would require some precision machining and jigging (easy enough with the right equipment), and a proper donor (which would need more research. My Type 9 suggestion is just a spitball-- it's somewhat easy to acquire, light duty/smallish, and was made with several shifter locations... beyond that, I have not done the research because I can't overcome the first point).

 

Your bio says you're in SA. Maybe I can bring you beer to get you to work on my stuff??

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It's in the 520 section so J13? Same 4 speed as the 510 (more or less but J series)  A B-210 A series dogleg would be close (but probably even rarer) and the later 210 had two 60 series 5 speeds.

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It's in the 520 section so J13? Same 4 speed as the 510 (more or less but J series)  A B-210 A series dogleg would be close (but probably even rarer) and the later 210 had two 60 series 5 speeds.

 

 

Yes, mine is J13.  Transmission is the same internally, but (at least from what the transmission guy was pointing at in his shop) different bellhousing, and since it's integral to the rest of the case, I don't see a simple swap.  Maybe he was pointing at something else, or there are some transition-year units that will swap in (???).  Are you saying any of the ones you mention will bolt to the back of a J13?  If so... hmmm.  I wonder what the shifter situation is like on them.  I don't have the energy for anything more than a slam-dunk 1:1 swap.

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No only meant that they were similar strength and size. I don't think the J and A series have the same bolt patterns.

 

I think there was someone on here recently with a 620 in Mexico. I think he said it had a 5 speed. J series were used elsewhere in the world when we went to the L series. Mexico got a J18.....

 

 

 

 

 


Thought I'd start a thread about the mexican J-18 and JDM J-16.

The J18s were used in Mexico in the Datsun Sakura (180SX Silvia) right up into the 80's. They are essentially the same as the other J-series and E1 and C, which were based on the BMC b-series engine. But they are 1790cc and came with 5-speeds.

A couple differences are that the motor mounts mount in a different (middle) location than the other J, E1 and C engines. But if you look at the picture, you can see the front mounting plate, and that is where the non J18 engines mounted. I would almost suspect you could put mounts in that older style location.

The other thing I read is that they require the J-18 oil pump, and can't use the others for some reason.

Doesn't seem to be a lot of info out there about them. So please add if you know more or if I got something wrong.

These pics belong to a guy named Oscar on car domain. Who has this in his 710. Here is a link to his CD page.

Oscar’s Datsun 710

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Thanks to my declining ability to do real work, I had to find a shop to work on the truck... and they bent me over pretty hard for what turned out to be a simple clutch and pressure plate swap (parts are $83 at Rock). *sigh* I'm getting too old for cars that require maintenance.  But... it's fixed.

 

Truck has to go back to the shop next week.  It seems they didn't replace the pilot bushing, and it is now squealing like a stuck pig.  *sigh*

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I'd expect the release bearing to make noise more than the pilot bushing.

 

Both the pilot bushing and the release bearing will make noise when the clutch pedal is down. So if the release bearing was not replaced do it now also.

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Update: Was able to get the Datsun back to the transmission guy.  I guess he should have spent the $2 for a new bushing the first time so he didn't have to do a lot of work twice.  He certainly charged me enough the first time.  Hopefully the problem doesn't return... he was using a lot of subtext in our conversation like he might not "honor" any additional warranty on his work.  Here's the pilot bushing he replaced this go-round.  It's unclear how much damage and distortion is from him removing it versus what was already there from the previous trip to his shop.  Clearly, it is not very square.

 

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He also took some pictures... I'll post them up when he sends them to me.  He pointed out some "oddities" about either my setup, or 520 in general about the transmission.  Maybe you guys can chime in for clarification.

 

There are no alignment pins between bellhousing and block... which means all of the alignment has to occur ON THE BOLTS themselves.  He said the bolt holes were pretty clean and tight, but I could see a pretty serious alignment problem if those holes ever got warbled out at all.  Also, he said there are no threads on either block or bellhousing.  Instead, they attach using a regular bolt and nut, which means the 2 parts are just held together by a 'pinch.'  From a mechanical fastening perspective, this is, frankly, sloppy engineering, plus it probably makes alignment (again, no pins) even harder because you can't just thread in a couple of bolts to get it aligned.  The bellhousing has a PROVISION for 2 alignment pins, but they definitely could never have been in there, even from the factory because it is obvious from the touch point mark on the metal (think of a "gasket" line where the bellhousing meets the engine), the 2 holes where pins would go are interferenced on the engine side... as in, a pin couldn't be in the bellhousing and align with anything on the engine.  Make sense?  Hard to explain without pics.  Hopefully he'll email them to me soon. 

 

As an aside, thanks to the pics he took, I now have a pretty good understanding of how the shifter arm mechanism works.  For those who are unfamiliar (again, pics will help), the north-south movement uses a pretty conventional rod movement that goes through an o-ring seal.  However, the east-west movement is done with a kind of flappy thing that is OUTSIDE the transmission (that's something modern transmissions keep inside and wet).  The piece looks a lot like if you hold your hand out to give a handshake, where the thumb is the shifter handle coming up through the floor.  To do the east-west, that piece rotates on a centerline (like you're rotating your wrist to turn a doorknob).  The major design issue I see with this is that, it uses a rudimentary bushing-around-bolt setup which, after 50 years starts to get pretty warbled out... because it's outside the transmission, and so it's dry (and subject to all manner of weather, road grime, whatever).  That piece could be substantially improved with a little machine work to allow pressing sealed bearings into either end.  But... this is all in my head.  I don't have energy (or a spare piece) to actually do this modification.

 

Sorry for the wordy explanation.  Pics when I get them.

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There are supposed to be dowels between the block and the transmission. They look like the ones used on the heads.

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That's what I would have expected, but it would be physically impossible for dowels to be in the transmission holes AND still butt up to the block. The holes "align" with solid steel... not another hole.

 

Maybe some PO swapped out the transmission for something else??? But from what?

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The bolt hole is enlarged and the dowel is hollow for the bolt to fit through. Trust me it will have them.

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I appreciate your knowledge and experience, but I was looking at the actual parts. There is no metal at the location where the transmission pins would need to engage the engine. Here are a few pics. Note the dark metal versus the light metal along the face of the bellhousing. The dark metal represents exactly the touch point where the engine and transmission attached. As you can see, not only are the dowel holes not in that dark metal area (and therefore not contacting any part of the engine, the innermost edge of the dowel holes ARE in contact with the engine... in other words, if a pin were there, it would be interfering with the engine casting right on the inside edge by about 1/16". I don't know if I have a factory Frankenstein from late year model build-out (truck is a May 1968 build number, IIRC), where they were scavenging whatever parts they had left in the bins (I've seen this "parts bin Frankenstein build" on countless GM vehicles when I was close to that manufacturing process in the 1980's... even robbing rejects/prototypes/whatever from anywhere they could find them, to get the car through the line... I'm sure other companies have done the same thing from time to time)... or a PO did some kind of misfit swap, or what other story might explain it, but I can assure you, having seen it firsthand, if pins were in those holes, the engine and transmission would not be able to mate.

 

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The firewall at work won't allow them to show.... plus IE. I'll look when I get home.

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Here are annotated pics of the shift selector mechanism I tried to describe above. The slop is telegraphing some otherwise acceptable vibration up through the shifter arm in the cab, making an annoying buzz starting at about 45mph or so. I can sink the vibration by just sticking my hand on the knob, but, well...

 

If the shaft in the second pic could be turned smooth, then turned down on each end to accept a thin bearing, it would isolate the piece from the shaft better, and really inprove the east-west movement. I'll bet @mklotz70 could whip out a solution for that in a jiffy... for the 5 customers who might ever bother with it ;)

 

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I was wrong. But there has to be some way to align the transmission and engine together.

 

There should be a steel engine plate sandwiched between engine and transmission. I can only guess this is what aligns them.

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If you could find an E clip the same diameter as the striking rod, that's the thing in the second picture, you could slip it into the gap... BUT it must not be tight as it still has to rotate left and right slightly.
 
The biggest cause of slop on the aptly named 'Monkey Motion, shifter is the part not shown that grips but not tightly, the end of the striking rod....
 
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You can see the shiny area where the wear is and the mating part is also likely well worn too. I've slipped washers onto the pin that fits the hole, and it's been suggested replacing that pin with a nut and bolt that you can tighten to squeeze the fingers together. BUT again not too tightly.
 
 
Here is the pin held with an e clip. It's hard to find a thin enough washer to fit. Too thick and it will be too tight.
 
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Right side....
Ta7fVAo.jpg
.

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On another front, I ran across a complete Exedy clutch kit #06020 (same as just installed), that includes clutch, pressure plate, throwout bearing, pilot bushing, graphite for the bushing, and alignment tool for $40. It will go in my too-much-inventory spare parts bin, thus practically ensuring I will NEVER need another clutch for this truck.

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A machinist could either weld up the shaft and then turn it back down to original specs or turn the shaft down and then turn out a repair sleeve to go over the shaft.

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trans_44.png

 

The striking rod rotates very slightly left and right through the neutral gate and forward and back to select the gears.That minor wear doesn't affect any of those motions. Don't worry about it.

 

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