Transmission overhaul, 5 speed

beezee

beezee

True Classic
I've finally got around to taking apart the transmission on my '83 X. Thank you Steve for the writeup, it is VERY useful! The problem was grinding shifting into first unless the car was stopped, and grinding going into third unless I shifted very slowly and carefully. Inspection of the internal shows that the third gear slider is worn. Does anyone know where I can get this part?

I'm still trying to learn how the synchro rings function. It's getting late so I'll try to get more insight with fresh eyes tomorrow. Does anyone have any advice as to what I typically will need to replace to fix first and third?

Besides the usual gaskets and seals, I figure on replacing the shaft bearings as well. Are there any other common wear items I should replace as a matter of course? What about the taper differential bearings? I dread doing this because shimming may be a pain-in-the-you-know-what.

Thanks in advance for any insight-advice. This forum is a great place for X folk!

Beezee
 
beezee said:
Okay, I think I understand how the synchro rings function, adding friction between the gear and slider as the shift takes place, but what do the synchro springs P/N part number 4183876 do?

http://www.spiderroadster.com/xtrans7.htm
Click to expand...
I have just finished transmission rebuild with 3rd gear problems. What caused the problems in my opinion was that someone installed the clutch disk backwards. For a shift to take place one shaft must coast to allow the gear sleeve to synchronize with the gear and engage. Third gear has always been a bit iffy and that is part of the design of these boxes. I changed the synchro brake and gear. You must do a tooth count for 3rd gear as there are more than 1 ratio in this transmission. Last week I had a chance to take the car down the road for a drive and it shifted smoothly in 35 degree weather with GL-1 transmission Lube in the box. So if you have had the car all along and never had the clutch changed, then don't bother pulling the clutch plate. If this is not known, do yourself a favor and pull the clutch and look at it and the disk. If the disk was put in backwards it was the cause of all of your problems. 3rd gear slider, look in the UK or Henk Martins. Also what is required in this box is that the gears which are on bushings must turn freely without any drag. Any water in the box which will cause rust on these bushings will create drag and that will affect a shift. If there is drag use some 800 grit wet sand paper and polish the bushing and shaft. Oil it and see if it turns freely. If there is galling or pitting the bushing needs to be replaced. The 3rd/4th gear slider can be reversed and that is what I did. I put the side that was facing 3rd gear toward 4th gear and that also helped. I would have preferred to change the slider, but I am repairing a car for my wife's cousin and he ordered 5th gear slider instead and I didn't want to wait another month to get this car back together waiting on parts.


TonyK.

Grimsby Ontario Canada.
 
Thanks for the tips Tony. I found that Vick Auto has pretty much all the parts I need. I'm looking at replacing first gear, first and second synchros, third and fourth synchros, and the reverse idler. There didn't seem to be that much wear on the third gear synchro, but it was definitely looser than the fourth and fifth synchros. From the amount of grinding I was experiencing I expected to see more wear, but I'm hoping that replacing these parts will get rid of the grind into third. Your tip about the bushings turning freely may apply here.

The tapered hub part of first gear was obviously worn out, so replacing the gear and synchro is a no-brainer.

Beezee
 
Be careful of aftermarket sliders I have not had good results with these. If you can find an excellent condition OE one buy it, they are getting hard to come by.
 
This series on the 5 speed transaxle might help:
https://xwebforums.com/forum/index.php?threads/5-speed-transaxle-part-three-gear-sets.26322/

https://xwebforums.com/forum/index.php?threads/5-speed-transaxle-part-four-shift-forks.26404/


Stay away from non Fiat OEM transaxle parts as they can be substandard and the source of problems and grief once these parts have been put into service. First-second gear syncro are often not a significant source of problems. Third gear Porsche syncro is the most often source of problems. Replacing the syncro bands alone is often not enough, the slider, gear are often wore out too. Do check the parts inside the syncro bands as the band springs and blocks can have wear problems too.

Once the transaxle is all back together with know good parts, do not try to force the transaxle to shift faster than it is designed to as this will cause the Porsche syncros in 3rd, 4th, 5th to crash and die. Shifting time between gears is an inherent design limitation with Porsche syncros.


Bernice
 
Thanks for all the advice everyone, as well as the links Bernice. Other than the first gear cone which was completely worn out, the transmission parts didn't look all that bad to me. I'll try to post a few pictures when I get a chance.

Beezee
 
Here are a few pictures to show the wear in the transmission. The first one is first gear showing the synchro ring with no clearance to the gear. It will actually rattle around on the gear. Using the synchro from second gear yielded the same result.

Transmission 030C.jpg


And here is second gear showing some clearance under the synchro:
Transmission 031C.jpg


Here is the 3rd/4th slider. The teeth are the ones that engage 3rd:
Transmission 028C.jpg


Here are the 3rd/4th synchros. I am not sure which is which anymore, but the wear didn't seem that bad to me.
Transmission 032C.jpg


Transmission 033C.jpg


And lastly, this is the blood blister I got from using a slide hammer I made up from a two jaw puller, a motorcycle axle and a motorcycle flywheel. A little bit of pain, but hey, I saved some money!

Transmission 025C.jpg
 
Replace.
-1st gear.
-Syncros for 1st & 2nd gear.

-What about the straight cut reverse gear on the 1st-2nd slider and reverse gear? These are commonly ground up.
-Straighten or replace the reverse gear shaft as needed. Check the reverse gear shaft boss on the case, these can crack causing the reverse shaft to move when loaded causing reverse gear to jump out of gear.

-3rd gear syncro band. Yes, it is worn.
-3rd/4th gear slider, this one is dead. Engagement teeth on 3rd gear will be equally knackared.
-3rd gear, check for matching version in this gear box.

-Shift forks if worn.

-Bearings, Roller on the countershaft, input shaft bearing (small end). Usually the big bearings at the ends are OK.
-Diff carrier tapered roller bearings, since it is apart, it would be wise to replace them.
-Gaskets and seals.

Bernice
 
That 3/4 sliding hub is U/S, not replacing it will just mean third is still going to grind.

you need to post pics of the 1/2 sliding hub with reverse gear teeth around the outside of it... the internal synchro detent teeth need to be sharp and pointy... rounded off like the pic of the teeth for third gear mean it's U/S.

you need to post pics of third gear on the cluster shaft, close ups of it's synchro detent teeth... if the sliding hub is that U/S then chances are the gear is also U/s...

SteveC
 
Once again everyone, thank you for your advice. Here are a few more pictures:

This is the reverse pinion gear:
Transmission 036C.jpg


Here is the mainshaft showing reverse:
Transmission 043C.jpg


Here is the 1st/2nd/reverse slider showing the reverse teeth:
Transmission 044C.jpg


And this one is third gear:
TransmissionC.jpg


Out of these four, I have ordered a replacement reverse pinion gear.

Beezee
 
1st - 2nd slider is sort of OK not great.

Replace 3rd gear, it is worn and will not shift properly. Same applies to the 3rd -4th gear slider and syncro bands.
Know 3rd gear is the MOST stressed, MOST abused, MOST problem prone gear in this transaxle. Most un-wise to not replace ALL the bits related to 3rd gear.


Bernice
 
How many hours have you taken to get to this point? Do you want to do this chore again? Replace ANYTHING that looks suspect. Pay the bill, know you did the right thing, and then you won't worry. It's not worth not doing unless you value your time as $1 an hour.
 
Advice taken, I will order a replacement 3rd gear. So far I have ordered 3rd and 4th synchro rings, 3rd/4th slider, 1st and 2nd synchro rings, first gear, and reverse pinion as well as gaskets and seals. I still need measure the shift forks for wear, but visually they don't appear bent or worn.

Beezee
 
Mine makes a nice crunch going into 3rd. Is there any foolproof way of telling in advance which version of 3rd gear I have? There seem to be a least three different ones. Mine's supposedly an '85 but the models we got here tended top be parts bin specials. Living where I do, parts can take a couple of months to arrive. OTOH perhaps I really need to see what else is worn first and just live with the delay.
 
I have received my parts orders, first gear, synchros, third slider, reverse gear, gaskets and seals, some bearings, stake nuts and some Redline MTL. Now I can start to put things back together. Fortunately, or unfortunately, depending on one's beliefs, I'll be worshiping this Easter in the church of Bertone, with the holy scripture of Steve's 5 speed 101.

Transmission 047C.jpg

Beezee
 
I got everything back together and took the car for it's first drive with the rebuilt transmission. I'm stoked to say everything works great! No more grinding in first and third. This information from this forum was invaluable in the rebuild. Thanks everyone...

Beezee
 
A little late to the party and it appears you have already received excellent advice on the subject. I would, however, like to add to the discussion on the subject of the reverse gear idler. The tooth pointing you see on the reverse components has a different requirement than the tooth pointing on the synchronizers. With the synchronizers, you will notice the angle of the tooth points is much more acute than on even a brand new reverse idler. It sounds like you got the gist of the synchronizer function and can appreciate the importance of that angle and the requirement for it to be rather sharp so I won’t go into that.

However as is the case with most manual gearboxes, the reverse gear in these transmissions is not synchronized. Rather, it is of the sliding gear sort. So the points have a different requirment. Yes, they do serve to index the teeth into alignment in order to complete the shift, but they also serve to prevent the completion of the shift if there is appreciable rotation between the gears, say in a case where a driver tries to select reverse while driving forward (can you imagine if you tried to select reverese instead of 5th at 50mph and it actually completed the shift :eek:). Moreover, you don’t want the teeth to suddenly engage even if the only energy you are absorbing is the inertial energy of a free spinning input shaft as this could lead to the teeth breaking off. So what they do is point the teeth more obtusely such that they will “skate” along (rather than engage) until there is no relative speed. This is the crunch/grind noise you hear if you try to put the car in reverse without putting it in another forward gear first. Putting it in a forward gear with the car stopped uses the synchro of the forward gear to absorb all the energy and stop the input shaft from spinning. Then when you go to put it in reverse, the gears are still largely stopped and the tooth pointing merely indexes the stationary teeth into engagement.

So the fact that your reverse gear points are rounded is not automatically cause for alarm... up to a point (pun intended). If they get rounded or chipped to the degree that they will no longer effectively index a rotationaly stationary gear, you will get occasions wherein the reverse shift is effectively blocked and you will have to try again to select reverse gear. As stated above, if you have grinding going into reverse it is because there is relative motion so you may have clutch issues or poor technique. The tooth rounding/chipping is a result, not a cause. Furthermore, I believe the reason the form is generally pointed to begin with has more to do with the manufacturing equipment than anything else as you will see new reverse gears that have a rounded endform like the Land Rover parts shown below. They didn’t wear like this, they were made like this. I suppose the idea is that they may end-up rounded anyhow so why not make them rounded and skip the debris generation.

All that being said, if the part is available and cheap, it doesn't hurt to replace it.

PV


land-rover-series-3-gearbox-reverse-gear-lg.jpg

097_4.jpg
 
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