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FS5W71B 280zx transmisson rebuild


Dave WM

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11 minutes ago, Dave WM said:

I would be so all over that. We were looking a property up in NE Alabama, oh my there was a 40*60 climate controlled shop with what looked like at least 12ft ceilings.

Get this there was a body shop and alignment shop down the street. I told her I can retire and go get an apprentice job a the body shop, rest of the time I will be in my shop. she can have the house to herself!

LOL! Alabama? What is there?  Orlando was ranked number 3 best places to retire recently. Alabama has 5% state income tax but no SS tax or pension tax past 65.  

Then again, we are going to become the new PR so things may change. 

Edited by JSM
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  • 3 weeks later...

so the new inner races for the needle bearings should be here soon, hope to start the assy process.

Question on using press, do I set the gear end clearance during the press in cycle? FSM has you press the main shaft in with 1st and 2nd installed. I assume I should be checking those to spec as I near the full press in position. Seems like I could "over press" pushing the main shaft too far into the adapter plate bearing.

The FSM has you going that far then pressing in the counter shaft with the main gear on the front of the CS not installed. the 3rd gear goes on after that part of the CS is pressed in, then finally the main CS gear and 4th (input shaft and gear) go on together.

 

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started re assembly. All going according to plan. I had to figure out a way to jig up some things for pressing the bearing and shafts etc... not hugely difficult, just a bid fiddley. Mostly I used 1" and 1.25" steel pipe like used for plumbing. its comes pre cut in various lengths. that and some mounting flanges for same pipe to act as stands. then the normal sockets for various drifts.

I followed the FSM sequence, you have to put things on in the right order to prevent creating situation where a gear is in the way of another gear.  I have some videos I will post up later, since you tube got rid of the video editor, they will be raw, uncombined etc...

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Is this the one Dave?  More interesting to talk out here.  Somebody else might know something.

The bearing and spacer must have been in the vicinity when i took it apart  Maybe the spacer positions the small gear to match the other gear, and that's where the noise is coming from.  You might need the spacer too.

image.png

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a little background on what ZH and I are talking about..

after I put the trans back together (see my multipart video) I give the input shaft a test spin. It has a noticeable tick tick tick, very regular  high freq (every few degrees of turning the input shaft results in a tick.

At 1st I was thinking of the oil gutter, pretty sure it was not a bearing or gear rubbing, too regular. So I took the trans apart back to the gear cluster in the adapter plate mounted on the vice.

spinning the correct direction results in the tick, reverse the direction and no tick. I used the mechanic stethoscope to trace the sound back to the back side of the bearing plate, then down to the reverse idler shaft. Confirmation was done by removing the idler gear, no more ticking. For those that may not recall I had a chewed up idler gear, Zed Head was kind enough to supply a replacement (NLA 23t gear). I used that idler for the rebuild. It would seem that best practices would be to always replace gears as a set, it seems the counter shaft (small gear pictured above) needs to go with the orig gear. I temp replaced the old chewed up gear and no more ticking. To further test the directional sensitivity of the noise I remounted the mis matched gear but did it backwards, resulting in the ticking now happening when the input shaft was rotated backwards. There must be some odd wear patterns that result in the tick with the mis matched set, hopefully the gear above will resolve. in case anyone wondering the reverse idler will not work when mounted backwards, at least not without some machine work and or thrust washer changes and then you still have to grind the teeth so they will engage the slider gear.

 

 

 

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I just examined the two idler gears under bright light and a magnifying glass. the old chipped up but no ticking idler gear shows noticeably more wear by looking at the back side where the gear teeth are cut flat (the front side is rounded more to help engage the non syncro reverse gear on both gears by design, so looking a the back side make for easier comparison). I assume the countershaft gear has a like amount of wear. I therefore would guess the uneven wear is setting up some kind of impact that is resulting in the ticking.

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don't need the spacer or bearing just the gear. I don't know as I did not try it with oil, but I did tick even when flooded with oil during the assembly (I literally poured gear oil on it while I was testing). It was actually louder when the assy all back together (before I took apart to start searching for the source of the tick), I guess with the bearing plate bolted to the alum it just acted like a sounding board. After the noise sidelined me on the 1st try I did not want to put it all back in with any known problems. That being said I do not recall ticking but more a loud grumbling noise which I assumed was bearing noise. it was so loud it prob would have drowned out the ticking if it was there thru the oil. when I 1st got it and did not do anything but seals and the gear, I did not do an extensive bench test for noise. It was not quiet and I assumed that was normal, much better now, but for the tick (that's all I hear, before there were other noises as well, part of my lack of experience as to what "normal" is.

Edited by Dave WM
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all back together, I test spun it with a drill, I get an almost wa wa metallic rubbing sound that seems timed to the counter shaft. It seems loudest at the very front of the bell housing. The timing is based on the wa wa not syncing up with the main shaft but with the counter shaft (I pulled the rear housing off and could see it clearly matching the counter shaft staked nut).

There is not much that could make this sound except I presume the counter shaft gear somehow coming into contract with the front housing. I did reinstall the front cover and did have the shim and it seemed the correct thickness per the spec sheet for the bearing measurement. Its loud enough I think to leave a mark so I will pull the bell housing and see if there is any evidence of contact. I may even just space off the bell housing 1mm and see if the sound goes away.

this is a real bugger. But the upside is  recent trip to a local JY produced a very good example of another ZX 5 speed. I cleaned it up, replace the obvious leaking seals examined the gears, still had some chipped rev idler, must be a common problem. I spun in up on the drill and it sounded great. I am not going to do anything else to it, the bearing looked and sounded good as well.

Its nice to have something to compare to. I will prob install this latest one and just keep working in the noise issue from the rebuilt one. At least I have some confidence in my use of the drill to spin the input shaft. Will know for sure if the newest trans that passed the drill test sounds good once it is installed.

 

 

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