w5m33 reverse problem

[warbo]

Hi guys. long time no. hear. Have a 97 hsg with w5m33....... Had a problem last year with the vehicle jumping out of reverse gear. have since had the gearbox reguilt for $1600. Reverse gear was good but only for around three months and then it started jumping out again. I am a maintenance fitter myself but cant nail this problem so hopefully if I give u some info, then someon out there might be able to help me.
1.with the shift cables detached, reverse gear still jumps out. (cables not stretched)
2.when changing into reverse gear, the movement from the gear stick feels complete. eg. is going all the way and not getting stuck.
3. with the handbrake on, if i try to use reverse gear then many times I can lift the ass end of the car up and stall the engine, it doesnt jump out of gear.
4. If i then release the handbrake, it jumps out of reverse gear as soon as the car starts to move, but the gearstick hardly moves out of place.
5. and if i put my foot on the clutch and release slowly from point 4 (above), then the car starts to move an inch or so in reverse before jumping out. eg. each time it jumps out, i dont have to move the gear stick to select reverse, simply depress the clutch and release slowly.
6. No problems at all chaning up and down on all forward gears and no noises when using all forward gears.
7. the problem occured after i placed the gearbox in reverse gear in a hurry from being stationary.
I would really like to be able to fix this annoying problem......anyone know how to fix (not replace) gearbox???

 

[4piknup]

i can only think the reverse selector inside back of gearbox maybe bent therefore not selecting reverse fully and allowing it to jump out of gear.

 

[milkandoj]

An aluminium selector would snap not bend, and i can’t really see a metal one bending, the metal ones are beefy.

When i striped first gear i could get it into gear then it'd move forward a tad and jump out like you describe. But unless you did something crazy in reverse i can't see you stripping reverse cog.

 

[4piknup]

maybe put it in reverse with the shifter then pop rear cover off and see if reverse is fully engaged. seems to me it isnt.
how can this be? bent selector, worn selector, roll pin worn or wrong way installed, loose rear nut, excess free play in shaft? i dunno what else might do it whether likely or not.
maybe while you have cover off, maybe manually select reverse at the selector all the way and try that. surely ok to reverse 10 meters with cover off.

is there any brass or steel in gear oil?

 

[(2much)]

Maybe your roll stoppers are worn out, and the engine rocks excessively as you go on and off power, you may be able to watch this with the bonnet up, and a helper watching as you do the handbrake method, then switch to actually rolling backwards, see if it pops as the engine rocks, or if it's at least consistent

 

[EVO-00X]

If you've already checked the shifter cables arent stopping too short of engagement, interfered with or the small nylon bush in the shifter linkage isnt worn, I reckon more than likely it would be worn keys, springs and synchros in the 5th/reverse gear hub and slider. Easy and cheap enough to replace as they are in the end case of the gearbox.
In the meantime a free check is to fully undo the reverse light switch at the top of the gearbox, unscrew it all, then screw it back in but not too tight. Then try it.
If it still does it next I'll be checking the spring and ballbearing for the 5th gear shift rail. You can do this from outside the box above and to the left of where you fill the gearbox up with oil. There will be 3 x bolts on top of eachother. 5th/Reverse is the top most bolt. Remove it and the spring and ball bearing inside it. Compare/swap the spring and bearing with another spring and bearing from one of the other bolts there. Be careful not to lose these small parts. A magnetic screwdriver or something might be a good idea to help remove the bearings. Then try to see if you have the same problem.
If not, then it'll either be worn teeth on the input shaft, input shaft has excessive movement due to worn bearings, or something wrong with the operation where the 5th/reverse shift rail notch sits inside the reverse gear idler arm (inspection will require full teardown of the gearbox cases).

 

[warbo]

If you've already checked the shifter cables arent stopping too short of engagement, interfered with or the small nylon bush in the shifter linkage isnt worn, I reckon more than likely it would be worn keys, springs and synchros in the 5th/reverse gear hub and slider. Easy and cheap enough to replace as they are in the end case of the gearbox.
In the meantime a free check is to fully undo the reverse light switch at the top of the gearbox, unscrew it all, then screw it back in but not too tight. Then try it.
If it still does it next I'll be checking the spring and ballbearing for the 5th gear shift rail. You can do this from outside the box above and to the left of where you fill the gearbox up with oil. There will be 3 x bolts on top of eachother. 5th/Reverse is the top most bolt. Remove it and the spring and ball bearing inside it. Compare/swap the spring and bearing with another spring and bearing from one of the other bolts there. Be careful not to lose these small parts. A magnetic screwdriver or something might be a good idea to help remove the bearings. Then try to see if you have the same problem.
If not, then it'll either be worn teeth on the input shaft, input shaft has excessive movement due to worn bearings, or something wrong with the operation where the 5th/reverse shift rail notch sits inside the reverse gear idler arm (inspection will require full teardown of the gearbox cases).

Thanks to all replies. I am familiar with the top rail spring loaded detent and removed spring yesterday. Just didnt have a magnet to remove ball and therefore couldnt confirm if ball was locating correctly into detent.
Yes will try to remove the reverse light sender unit as is very easy and who knows..
Please note, I cant even reverse a meter without reverse gear disengaging. When I had the box rebuilt in Adelaide (by a reputable mechanic with extensive rally experience), he was unable to locate anything bent/broken/worn/or dodgey in relation to reverse gear. Had all new bearings, re shimmed and another fork for first gear (had worn plastic lugs on the fork) replaced.
No bronze of chunky bits in oil, and gearbox still runs very smooth (except for reverse).
If i remove the end cover plate off the box to check if reverse is engaging all the way, will this then allow bits and pieces around the bearing plate to move, or are there independent fasteners holding the bearing plate to the rest of the gearbox. I have never taken this gearbox apart myself so is all new to me. Cheers

 

[EVO-00X]

You can remove the end cover plate off the gearbox without any issues (well there is one, drain all the oil out first :lol: ).
The reverse synchro set may fall off but thats OK as you can inspect it for wear and gives you a look at how the keys and spring are sitting inside the hub.
Look at the end cover you just removed and inspect the condition of the reverse wave spring and cone - its the thin funny looking large washer in the back cover. Make sure its not deformed and that the notches align in the right spot otherwise it can be a reason why your reverse pops out also. If it looks good, use the shifter lever to shift into reverse to see how the spring and keys work whilst its engaging and disengaging. The spring might even be worn or weak and not pushing the keys properly, or the keys may be worn and deformed too.

 

[warbo]

ok thankyou evo 00X. had tried checking the gearbox mounts, removing te reverse light sensor (could see the indent in the shaft perfectly). Strange thing that happened this morning though, was when i tried to select reverse, the reverse gear engaged and the vehicle moved about 3 metres before crunching and stopping. Guess that may show teeth may not be stripped as otherwise power would have not been transmitted. Will leave the sleeping dog resting this week end so atleast i can drive around forward. Just have to be careful where i park and make sure no-one parks in front of me. Will attack the box early next week. Cheers.

 

[doommachine]

Hmm, well if you can stall the car with the handbrake on, and repeatedly do this, it can't be the gear - it would have to pop out once at least. So, it's fine under load? Which indicates to me that the problem is some clearance being too great when there is no load.

If you just hammer it in reverse does it pop out? (ie, load the car up a lot)?

I think trying 2much's method is the best bet, rock it with the handbrake and then let it go to see if it then pops out, or as he suggest use a helper to see if the engine moves excessively.

But since you say you physically did something which caused this to happen its possible something is broken internally..

Does it pop out of fifth? Can you pull it out of fifth/reverse when there is load on the gearbox?

Factory service manual states that if it pops out of a gear it can be a shift fork wear or poppet assembly. TBH I have no idea what the poppet assembly is but since theres a spring involved it seems to me like something worthwhile checking. If the spring has worn, theres no guarantee that the people who rebuilt the tranny checked it.

http://www.vfaq.com/mods/Trannyrebuild.html

This isn't immediately helpful to your problem but at least it shows where the poppets are etc...I'm not sure if they can be checked with the transmission in the car.

Also, this may help you

http://www.lilevo.com/mirage/92-96%20DSM%20Manual%20Transmission%20Service%20Manual%20.PDF/MT.PDF

 

[warbo]

thanks Doommachine. Just pulled the side cover off today. i noticed the reverse synchro ring was not sitting flat (gearbox still in car) in the assembly and when i touched it lightly, it fell out. At this stage i noticed three rectangular metal lugs behind the synchro ring. one was not sitting in "home" position where as the other two were. I also notice a large internal C-clip (not a full round internal clip) which looked broken as it was in such a position that one of the metal lugs was not being retained by the clip. I have been assured that the C-clip is only about 270 degrees and is supposed to retain all three metal lugs. these lugs mate into notches in the back of the reverse synchro ring for some reason.
WIth the synchro ring and large C-clip out, one of the small rectangular metal lugs fell out (uh oh...that wasnt supposed to happen.....so i know now). So tomorrow morning i will have to undo the large nut holding the reverse/fifth gear assembly and remove the hub. I have been told there is some type of energiser spring behind the hub which is supposed to help hold the rectangular metal lugs in position. Im expecting to find something in there broken or out of tension or something.
Does anyone know if the tension on the ugly round looking wave spring in the end cover plate can loose its' tension.?
And also does anyone know if the small notch in the internal C-clip is supposed to mate with a groove in the back of one of the three rectangular metal lugs (stuffed if i can remember what they are actually called :blink: )????
Looks like i will have to find a gear puller (as apposed to large gear chipping screw driver) if the hub assembly is tight on the shaft.
Oh well.....learn a little bit more each day.......maybe.......i think......not sure :huh:

 

[EVO-00X]

The C-clip you're referring to is the 'spring' and the little metal rectangular lugs are the 'keys'.
If you look at the springs there are 2 notches in them on both ends. They are to go into the back of the keys.
Pictures speak a thousand words so here you go mate
You cant go wrong if you look at my pics.

Remember, to remove the large nut in the middle of the hub, you have to stake out the notches with a hole punch or something because they are squeezed in to stop the nut from coming loose.
Also, you will need to fiddle with the gear lelector to lock the gearbox up so it doesnt spin when you're trying to undo the nut.
Last of all, knock out the pin inside the shift fork outwards not inwards... ie, knock it from inside so it falls outside. If you knock it toward the gears it will get stuck and cause you much grief :lol:
Then remove the hub, reposition the keys and springs, and fitment is the reversal of what you just did. DONT forget to re-stake the nut when you're finished.
This is the easy end of the gearbox :lol:

 

[warbo]

Thanks so much Evo-00X. One of the first photos confirms my suspicions as to my problem. Your photo depicts the spring with the little bend sitting in behind one of the keys. The sping also holds all three keys in position. When i removed my reverse gear synchro, the little bend in the spring was not located in one of the keys. The spring was in such a position that one of the keys was not in contact with the spring at all!! I guess the next thing is to find out why that spring clip moved?? Maybe when i got the shits initially and "banged" the box into reverse in a hurry causing extra shock on a weak spring??
No problem understanding what to do with the nut with the pin punch before removing, and after re-tension.
Only have one question. To enable the keys to be relocated correctly, do I need to pull the reverse/fifth cluster completely off of the shaft?? If so, I guess i will go shopping for a flat back twin leg gear puller.
Excellent pics. cheers again.

 

[warbo]

ok.....I removed the fifth/reverse gear cluster and inspected the keys and springs for wear. The springs didnt appear to have a lot of tension although I did not have a new one to compare. One of the springs was slightly warped and would not sit flat in the rear of the hub. The spring in the rear of the hub was not sitting in the correct position (eg. the notch in the spring was not located in the rear of one of the keys, and therefore one of the keys was not in contact with the spring). This is exactly what i found with the spring in the front of the hub. The keys did not look worn, although once again, I did not have a new key to compare with.
As for the spring located in the end cover, it showed slight signs of wear on the parts which come in contact with the reverse synchro, and the two little legs were located in the grove in the assembly bolted behind it to the actual cover as required.
I elected to swap the springs in the hub eg. front to rear and rear to front, as they appear to be an identical part, to see if this would fix my problem. If not, then it would be easy to replace the bent spring now that it is located in the front of the hub near reverse synchro.
So put it all back together feeling rather confident. Jumped in and hit reverse. and ...... :angry: :angry: :angry: :angry: it jumped out of reverse gear again.
Any ideas???? :blink:

 

[EVO-00X]

:lol: it doesnt hurt to buy new keys and springs when you have it apart, they arent expensive but can be a bit of a wait for them.
Can you please take a pic of the reverse wave spring and back of the end cover.

Sometihng you can do in the meantime is get a mate to sit in the car and select reverse whilst you're looking at the shifter linkage inside the engine bay. Make sure they dont touch anything.
Then get him to slowly release the clutch to put some load on the engine til it moves forwards/backwards. Hopefully your engine mounts arent worn enough that there is excessive movement when there is load on the engine in reverse gear. Aim is to see if the engine moves forward/backward enough to make the shifter linkages hit against icoola piping or whatever.

 

[warbo]

Im up in Darwin. Went to parts shop and they couldnt work out which part number for the energiser springs as their computer gave them two part numbers. Only about 9 dollars each ex sydney. Forgot to ask about keys. Anyway just threw it back together as needed vehicle for the weekend. I have photos of the wave spring and energiser spring and hub on my phone. I know how to import them from phone to laptop, but not sure how to import from laptop to website. Probably not too hard. The engine mounts are relatively new. Gearbox mounts sound. gear linkages are free from obstacles. I tidied up the cable mounts and now notice than when the reverse gear disengages whilst attempting to reverse, the gearstick definitely jumps about 10mm. Now that I am familiar with what to do, will replace keys and springs later next week. Not really that big a job. Im expecting to see the energiser spring out of place again when i remove the side cover again. Atleast i didnt need a gear puller to remove the hub assembly off the shaft. I was just able to remove it by hand. The roll pin on the other hand was a real bitch.... very tight.! had to use a g-clamp and spacer to "press it out. have photo and will display to make job easier for the next sucker, I mean motor enthusiast who tries to remove the pin whilst the box is still in the car (no room to swing a hammer on a pin punch!!!). Thanks for your help

 

[4piknup]

yea, i pushed that roll pin rather than pulled it and suffered a bit trying to get it back. i ended up cutting it with a hack saw and then had enough room to keep pushing it through. i know for next time though

 

[warbo]

energiser ring and reverse synchro, wave spring, and fifth reverse hub.

 

[EVO-00X]

The wave spring looks fine and not overly distored or kinked. When you reassemble the springs and the keys in the hub, make sure the notch on one spring is in key number 1, and on the otherside of the hub when fitting the spring make sure the notch on the spring is in key number 3. Basically the complete opposite key. eg 1-2-3 keys. 1 gets a notch, 3 gets a notch on the other side of the hub, and 2 doesnt have any spring notch in it at all.
How did you go with the ball-bearings for the selector forks? all there? springs OK and same heights?
Unfortunately if all these parts look good, and if your synchro looks good, your problem will be elsewhere and may be inside the front casing of the gearbox.
Either the fork in the shift rail end may be worn or there is a problem with the reverse gear idler arm or shoe.

Here's some more pics for you [glad I took heaps of pics during a build and put on computer ]. I've explained how it works inside the box so you can see for yourself if you have the kahoonas to open it up and check
Check the condition and engagement of the fork, arm, shoe and gear onto the input shaft. Also check the condition and wear of the teeth on the gear and the input shaft as well

Part number for the springs is: MD742441
Part number for the keys is: MD742777
Part number for the shoe on the reverse lever (if its damaged) is: MD735927

Good luck with it all

 

[warbo]

thanks for the pics, part numbers and info. After looking at the pics i now understand a bit more about how reverse gear selection occurs. Still got me stuffed what actually allows the reverse gear to "disengage" from the small shaft next to it as both are straight cut gears. As for the springs, i had just found a manual on line which shows the correct way to install springs (just as you described), which was not the way i put them back on last :angry: . In any case, i will be replacing springs and maybe keys next week. I know the springs were not in the correct position when i removed the rear cover, although believe they were in the correct spot before i slammed it into reverse (maybe shock load bounced out weak springs???) May be possible that the unintended movement of the springs is a symptom of a bigger problem, or if i have some luck (bull...t) the new springs might fix my problem :unsure: . thanks again EVO-00X and mike.