ZCar Forum banner
1 - 18 of 18 Posts

·
Registered
Joined
·
9 Posts
Discussion Starter · #1 ·
Hi,

New guy here. I put an '83 ZX 5 speed in our MGB, Rivergate conversion, back in 2007. At that time I installed all new bearings and synchro's and filled it up with Redline MT 90. The trans works great, really appreciate the 5th gear at highway speeds in the B, but has always had three problems since I first rebuilt it 50,000 miles ago:

1) If you are going downhill under compression in second gear it will eventually pop out of gear, not a problem in any other gear just second. I've lived with it this long and it doesn't seem to hurt anything but it is annoying.

2) There is also a very good chance that it will grind going into second, which seems to be a common problem from what I've seen so far, but I would be a happy man if I could fix that as well.

3)The third problem, less annoying as it seldom happens, is that it will pop out of reverse if backing up a hill for very far.

I've got some down time this winter so I've decided to pull it out, open it up, and see if I can spot any possible fixes. In searching the web I've found various bits of information that are somewhat related to the problems I'm having one, from 2005 and authored by "The Z Doctor", is about using stronger springs in the slider hub. At that time Z Doc had those for sale but the thread is old and I have not been able to find any contact info for him to see if they are still available. Any info about these springs or any other suggestions you have that may address any of these problems will be much appreciated.

Thanks,
Joe
 

·
Administrator
1983 280ZX Turbo
Joined
·
2,011 Posts
It may be transmission bearings. When they allow movement in the gear sets, trannies will pop out of gear.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #3 ·
Thanks for the reply!
I replaced all the bearings when I rebuilt it in 2007and it started doing all three things from the get go so I'm thinking that need to look deeper into it like maybe not enough spring pressure on the "keys" in the synchro hubs, too much clearance between the synchro ring and the cone on the gear, worn shift forks or sliders, or the wrong tolerance in the gear sets like you mentioned but caused by something else besides the bearings (I hope). Obviously the reverse popping out backing uphill isn't caused by a synchro as none are used for reverse gear in this tranny.
In an effort to get it right this time I'm working on getting as many ideas as possible before I open it up so if you run across any info or have more thoughts on the subject please let me know.
 

·
Super Moderator
8 / 71 240Z, HLS30-40031, L24-052899, Sunshine Yellow
Joined
·
105 Posts
You might check the springs on all the shift rod detent balls. They are in that center carrier plate and accessible from the outside. You could even try stronger springs if they are all intact.
There may be something wrong with the 2nd gear syncro or a bearing but that wouldn’t explain reverse.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #5 ·
I neglected to say that I had replaced the balls and springs for the shift rod detents a few years ago with little effect on the problems at hand but it did feel more positive when shifting so I'm counting that as a win.:)

I have the feeling that I'm battling two different problems with 2nd gear being the priority but if you have any more thoughts of things to check when I get into it please let me know.

Thanks!
 

·
Registered
Joined
·
1,275 Posts
did you use the shifter that came with the ZX trans? did you bend it so its not exiting the rubber boot to far forward?
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #7 · (Edited)
Rivergate took my Z shifter and cut, shortened, and welded it back together in an offset that places it closer to the driver for ease of use. It seems to be a well thought out modification and the shifter falls readily to hand. I did have to cut out a wee bit of the tunnel as the original opening did not allow the selection of 2nd gear, something that Rivergate said may be necessary. There now seems to be an adequate amount of space for the shifter to operate without contacting the body in any way.
One of the things I'm going to revisit before pulling the trans is the MG rubber shift boot as it seems like it may be pulling on the shifter when in second. I'm sure I checked it early on but will give it another look. There is too much snow on the ground to test drive but if I take out the screws holding the boot down I might be able to tell if it is a problem.
 

·
Registered
Joined
·
1,275 Posts
did you notch the Z shifter where it jabs into the trans? (not needed with the ZX shifter with the spring loaded pivot pin).
You want to make sure the detent balls are fully engaging, enough so there is a bit of play felt at the shifter when in gear.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #9 ·
Hmm, I'm not familiar with what you are talking about so I'd be interested in more information about that mod.

I just checked on the shifter and the pivot is currently the "older"? style with the round hole (I don't remember if the shifters were supplied on an exchange basis or if using the "old style" bottom was their preference) rather than the rectangular opening with the large, white, plastic "bushings" of the ZX shifter so "notching the shifter" may be called for.

If you would tell me what I need to know about this procedure and maybe a pic of two, or point me to a thread that tells me what I need to know, I would much appreciate it.

Thanks for the help!
Joe
 

·
Registered
Joined
·
1,275 Posts
just below the pivot point on a fixed pivot shifter, look to see if you have any "witness" marks where the rob part below teh pivot is hitting inside the shifter housing. If you see any you get a grinder and file the marks away and try again. Once you can see where the marks form under the pivot, you can get some light nail polish and paint that area, re install and shift thru the gears. again you want to see if the paint is marred. I will see if I have a video of it.
 

·
Registered
Joined
·
1,275 Posts
I did not go into the mod on this video, but if you look closely you can see the red mark where I painted the shifter to find the interference. If you have a ZX trans mission I would suggest you start your search for a zx shifter. Once bent correctly it works fine, but is too short. I ended up fabbing an extenstion (about 2") to get the shift knob in a more reasonable height.

 

·
Registered
Joined
·
1,275 Posts
but before you do any grinding you really need to make sure its the problem, again the witness marks will tell the tale.
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #15 ·
Thanks for the video and the link as I see what to look for now. I'll check that out and post my results when I have time.
J
 

·
Registered
Joined
·
9 Posts
Discussion Starter · #16 · (Edited)
Dave M-

I pulled the shifter yesterday and there were very obvious marks on the front and backsides of the shifter below the pivot so I removed some material, using a Dremel and a 1/2" stone, marked it up and checked it again. Had gotten most of it but saw that the notch needed to be a little wider/deeper so a little more work and tested it again with it showing that a little more needed to come off at the top of the divot so did that and called it good.

Thanks for the tip about the shifter having a little play when in gear as that really helped out. As second and reverse were the only ones giving me trouble I hadn't thought about the others until I saw the wear marks were both fore and aft on the shifter. After "massaging" both sides I now have very obvious play in all gears when in position so feel confident that the problem is solved but will wait until a decent day to take it out for a test. I will say that I don't get any play in the shifter when it is in reverse but as there was no indication of any more interference in the areas I had been grinding so if there is still a problem I'll look elsewhere but do wonder if reverse gear normally shows some play in the shifter when engaged or if it is "different" for some reason.

Also taking your advice and looking for a ZX shifter. I will probably need to cut and weld it above the pivot to work in the MG but that is not a problem.

Thanks again for the help,
Joe
 
1 - 18 of 18 Posts
Top