BC

Its actually very fun. I am in the same situation as John, just sans new parts because of a few, uh, issues with non-big4 suppliers. Nice, solid parts that have a correct orientation, etc.

John V

Hacker,

thanks for the kind acknowledgement but I haven't contributed nearly as much as some of you have. I've been meaning to buy a membership but as you can tell from my limited # of posts, I wasn't spending a lot of time here and it's easy to forget. Still, when I have a question, this is the first place I come and for that, I'm embarassed I haven't already joined. That has been addressed (I just paid for membership but thanks for your kind offer). I'm glad to be able to contribute this post and still feel I'm getting the better of the deal.

I haven't followed up recently becuase I've run into some parts problems that I somewhat expected and probably deserved for not going with our trusted suppliers. A vendor, (not one of our big 4) that shall not be named, was advertising new shift sleeves, in stock, for about 1/3 of the going rate. I called to confirm price & stock and felt that while it seemed too good to be true, I could not pass up the $200 per sleeve savings. Well, I'll be first to admit, I should have known better. After more than a week, some long emails and calls to my credit card company, I just this Thursday recieved my parts, so I'll be re-assembling the box this weekend if all goes well.

I will do my best to keep documenting this project and hope it helps others.

Randy - I emailed Jenn after paying for the membership... I can't remember what email address I used when I first came to Rennlist- I doubt it matches what I used in the on-line sign up form - I trust you guys will know how to fix my screw up and apply the mebership to this login name.

John V

These are all the new parts for the rebuild- approx $500 - good illustration of synchro wear.




First gear has special stop blocks and bands that must be assembled as shown-




Mounting some gears, like first, can be diifficult since gravity tends to pop all the assembled peices off - I slid these on in this fashion and inserted the bearings after. ** Remember to install the 1st/reverse shift sleeve with the unworn side towards 1st gear. Also note that I didn't remove 1st gears inner bearing race or shift guide sleeve since there was no need - to remove 1st gears synchro. After first gear goes on, a thrust washer is inserted (shown) and then 2nd gears inner bearing race (not shown). These shoud be heated or they're a bear to get on.




This is second gear- gravity helps assembly here. Notice the inner race is already on the shaft and the needle bearings are on the inner race. I found it harder to install gears this way and prefered to install the bearings from the top after the gears are in place (slide the bearing segments between the gear and inner race)




This is the shift sleeve assembly. The first part is the guide sleeve, the second is the shift sleeve (new), and that third part is a bearing inner race.




This is 3rd gear. Again installed to keep all the bits assembled and then the bearing segments are inserted after.




This is the bearing segments going in and then the thrust washer. These thurst washer go between gears that don't share a shift sleeve like 1/2 & 3/4. These, and the bearing races needed to be heated to slide onto the shaft- Otherwise, they had to be pressed on. Heated to about 250 deg F. they slide right on.




This is fourth gear.




This is the 4/5 gear guide sleeve. I find 5th gear to be a deceptive description since there really isn't a 5th gear in these boxes - 5th gear is not a gear at all but merely the locking of the input shaft to the output shaft ( bypassing the counter shaft). What most call 5th gear, is just a gear that spins the counter shaft and it has no impact on gearing at all... it just provides a surface for the syncro and dog teeth to effectivley lock the shafts together. This gear is actually on the input shaft and thats why the pinion shaft only really has 4 gears. As such the rest of the shift sleeve assembly and synchro can go on later since they'll just fall off now. The last picture is of the final shims.




These shims take up any free space between the final guide sleeve and the retaining ring.




This is the rebuilt pinion shaft complete. This assembly contains all the wear parts that I replaced during the rebuild. Other than new seals, this is the brunt of the rebuild effort. Below is a picture of the counter shaft lined up with the gears on the pinion shaft. I just did this to make sure all the thrust washers and gears were placed on the shaft correctly. It looks like everything lines up.




This is the sandblasted and hot tanked case ready for re-assembly. The counter shaft and reverse gear are laid in first. A new input shaft seal goes on (the old one was a Bit#h to remove).




I'm actually changing the order of re-assmebly based on some of the issues I encounterd during dis-assembly. I'm installing the input shaft first becuase I believe assembly will be easier this way.




Much of what I did today again reguired persuation. Were it not for the use of a press, some heat and some refrigeration, this would have been difficult. I don't believe this is the norm since I've heard of a few other gearboxes that have come apart and gone together without these steps.

The synchro and shift sleeve operation is much stiffer now. I'm sure some of this will improve once oil is involved but, I expect shifting will be a liitle stiff at first. I'm pretty confident there will be no grinding as the synchro spacing previously measured is much improved.

More to come if I don't run out of picture space in my photo hosting account.

danglerb

neat.

John V

The plot thickens-

after assembling all the shafts into the box, I'm concerned about one of the new synchros. 2nd and 3rd gears use the same part number synchro. When I received them, one looked slightly different than the other...not like the wrong part... just different. The synchro's clearly looked like they came from different manufacturers. One was clearly marked right on the synchro with a "G" (which i presume is "Goetz" and, this one had some ground faces as well as a lighter color. The other synchro had no manufacturer markings, nor were there any ground faces. The color was also darker- more like the 1st gear synchro which was also unmarked & unground. You can kind of see the color difference in the photos above. I didn't think anything of it since both came in bags with the correct part number and they matched up when placed against each other back to back.

Now, I think that ground synchro is going to cause me problems. When you engage a shift sleeve towards a synchro ring, the leading edge of the shift sleeves engagement teeth are supposed to slide "over" the synchro just slightly before they make contact to the synchro's friction surface. I beleive this is intended as a lead-in "ramp" to smooth engagement. Every gear has about . 06 of synchro engagement prior to encountering friction... except this ground synchro. On this synchro, the shift sleeves leading edges do not slide "over" the synchro even a little. It appears they they hit the face of the synchro... like the synchro is too expanded to provide a lead in ramp for the shift sleeve. It will engage but you have to force it on and I suspect 3rd gear is not going to engage as smoothly as the others.






Looks like I'll be tearing it down and getting another synchro... I'm not chancing getting putting this thing back in unless it's perfect.

danglerb

If you run out of space, try imageshack.com Its "slightly" tricky to get to the correct page on the site, but once you are there very simple to use.

Lizard928

is it possibly the selector ring, try disassembling and turn the selector ring 180 deg, then reassemble and see if it changes to the next gear, if it does then the selector ring may need a little filing.

John V

Lizard,

that selector ring is the new one and I measured both sides before installing it. If I had re-used the old shift sleeve, this likley wouldn't be problem since the sleevw was well worn. I'm going to re-check it but I'm reasonable sure its that odd ball synchro. You can see in the last set of pictures that each syncro has a machined step that snaps in under the dog tooth ring at the gear (not on the selector side). Look at the 2nd gear syncro and you can see there's rough plating on that step under the dog teeth. Now look at the 3rd gear synchro on the right. That same machined step is not plated.. it's shiny and I'm thinking it has been machined too deep, allowing the synchro ring to expand to a larger diameter than it should, which prevents the shift selector sleeve from sliding in over it. I'll know more when I get it back off.

Vilhuer

There is something strange going on with old style syncros. Below case was never really fully solved AFAIK meaning 4th gear syncro was changed to different one which worked but its not known what exactly that first part was.

https://rennlist.com/forums/928-forum/117661-4th-gear-synchro-modified.html

John V

Erkka,

Your reference is exactly my concern. Looking at the difference in that step at the back of the your 2 examples, it's clear one step is deeper and wider than the other, by a measureable - even visual degree. I beleive that step is critical since the synchro must be compressed (amost like a piston ring) to fit inside the dog teeth using that feature, as the retention means. If the step is too shallow, the synchro remains "over compressed" (where it's effective diameter is smaller) and if that step is too deep, the ring expands back too much (under compressed) to where the syncros effective diameter becomes larger than it should -potentially too large to enter into an unworn shift sleeve. Thats what I think I have going on.


UPDATE: It turns out the step is not the problem since they all measured the same within .001". I measured the synchro and its the leading edge/face of the synchro that is too thick. I measured the sleeves and the new sleeve ID measures at 3.360" (old worn one measured 3.380"). The synchro's leading edge needs to be smaller than this diameter (when snaped into the dog tooth ring) so that the sleeve travels "over" the synchro (instead of hitting and binding on the faces). The non geotz sinchro's leading edge diameter measured @ 3.350 (which fits into the new 3.360 sleeve) BUT the goestz measured at 3.370, which does NOT fit into the new sleeve (it does fit into the old worn sleeve indicating goetz syncros might me better for rebuilds where shift sleeves are not renewed). Here's a pic.

BC

.01 is quite a bit of difference John. Is that also the difference between a worn selector ring and a new one? Thanks for taking all these pictures. I will go into the garage and see if I can get some shots and measurements of my 1-3 synchros. They are also from your second source as we discussed.

John V

Brendan-

Yes .01 is quite a bit and because thats per side, it doubles when applied accross the diameter. Yes, thats also coincidentally, the difference between a new and worn selector sleeve. Thats why I posted above that these Goestz synchros might work better than non Geotz when the shift sleeves aren't renewed.

John V

Update 1/21/07


The tranny is back together with the (new) new synchros. It feels much better. I'm still waiting on a spring for the final shift shaft assembly. Thanks to BrendanC, I am also replacing my old open diff. with an LSD unit (that I'm also rebuilding).




The LSD unit was completely dissassembled, inspected and cleaned. Once apart, it became clear that the wear surfaces did not need to be replaced. This is tough to describe but there are 4 plates that work together to limit slip. The 2 friction discs (the round ones on top) are molybdenum coated with a rough surface that rubs against the wear plates (the silver plates below with 4 tabs). Because the friction plates can't spin against each other (because they are both keyed to the same shaft), only one side of the friction plates wear against the wear plates. You can see the difference in the plates shown. I deglazed the wear plates, and re-assembled everything with the fresh surfaces against each other. The unit produced 20 Lbs. Ft. of torque dry (using the WSM test procedure) where the manual only expects 14 Lbs. Ft. (I'm sure oil will change the figure somewhat).




This is the rebuilt LSD unit both out of and in the gearbox. For those that have asked before, changing over to an LSD does change the backlash. I had to shift the LSD .022" towards the pinion to get the backlash to match the old unit. This was a tedious process since the shim swap is time consuming and non linear. It took 8 attempts to get the backlash to .007 (where stock was .005) and thats as close as I could get it given that the thinest shim was .004 and swapping that one shim moved the back lash from .007 to .002 (which I thought was too tight).

danglerb

When this is all done it could be edited into such great teaching tool.

I "almost" think I understand how a transmision works, and its nothing like I assumed. If I have it correct the "gears" are always together in pairs, and the "shifting" occurs by engagement with the shaft?

John V

Dangler - yes, you understand it.