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I finally got the car put back together. I did the following:
* replaced rear main seal
* new synchros for 1st and 2nd gears
* minor OD rebuild
* lots o' gunk cleaning
* new 4th gear OD switch
* fabricated new wiring harness for OD
My plea for help was here:
http://www.brickboard.com/RWD/volvo/1460192/220/240/260/280/really_want_rebuild_m46_od_talk.html
It was an ordeal, although I have to say that the OD rebuild was the easy part. I have a spare OD that I may rebuild just for fun for the practice. So one thing that really screwed me up was the destroyed wiring harness. When I rebuilt it, I accidentally switched the +12v wire (yellow) to the solenoid with the ground wire (red) to the 4th gear OD switch on the top of the gearbox. I test drove it like this and apparently shorted out the new 4th gear switch I had just installed. After tracing the wiring faults and looking at the Bentley diagrams, I fixed it. Later, I thought it was the relay and switched it out with another that I thought was good. This was another wild goose chase since the replacement relay was actually toast.
This page from Duane H. was the most helpful in troubleshooting the electrical issues after I fixed the wiring harness (there are two troubleshooting posts):
http://www.brickboard.com/RWD/volvo/1377532/220/240/260/280/m46_overdrive_issues.html
This told me the relay I was using was bad and when I got a good one back in there, it told me that the 4th gear switch was dead. So to get the car going until I can get another switch, I implemented an inelegant solution. I built a cable to permanently ground the wire that would normally go to the 4th gear switch to the back of the OD, ala the solenoid ground (easy place to access). You just have to be careful as now the OD will work in every gear (you can have an 8-speed gearbox if you want). I will get another switch this week.
The one thing I hope to contribute is this -- you do NOT have to drop the trans crossmember and tilt the trans back to get to the 4th gear OD switch on the top of the case. Take a 22mm deep socket that has a hole in the side as the detent for the ball bearing in your socket driver. Use a punch that is sturdy enough to fit into this hole and work as a lever. Since the switch shouldn't be heavily torqued into the case, you should be able to loosen or tighten the switch enough with this jerry rig so that you can manipulate it the rest of the way with your fingers. After all the work I had put into the car, I really didn't want to unbolt anything else and since I didn't have a crow's foot for this and my driver and deep socket wouldn't fit in the space of the tunnel, this seemed like the best compromise.
Thanks to everyone (especially Duane) for their help. The clutch is smooth, it goes into 2nd gear easily, it's quiet, and the damn thing better be good for another 100k, when the engine hits 450k and we decide what adventure we'll embark on then. Cheers.
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This seems like an appropriate place to ask! It turns out that my M46 overdrive isn't working because the red wire at the relay isn't shorting to ground when in 4th.
I confirmed this by (with the engine off) using my meter to pull the red wire to ground.
Is there any harm in permanently closing this connection? Obviously, I'll do my best not to put the overdrive on in the wrong gear, but is there any possibility I could damage the transmission if the overdrive engages in a lower gear?
Thanks!
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Tim,
Operating the transmission in reverse will damage the overdrive. Are you sure that the switch harness is intact. It may not be the switch at all.
Goatman
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I suspect the wiring harness. I'm planning to do this as a temporary fix, just until the weather improves enough for me to spend some time inspecting the harness under the car.
In the meantime, I guess I just need to be very vigilant about using the switch. I've had a nagging feeling this car is going to self destruct... now I have a switch that will let me do it!
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Great! I'm glad. I need to replace the synchros in my 1st gear, and 2nd isn't much better. Where did you find a guide for that part? Or had you done it before?
Happy Bricking!
--
1990 740 Turbo, on its way to stock specs, maybe beyond
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I had to give you a thumbs up for returning and giving a detailed and extremely useful follow-up report on your M-46 problem. I especially appreciate your inventive work-around description and removal of the solenoid. I have an M-46 as well, and although I'm not having any difficulty now, I will at some point. I have saved this thread for the future. I would, as it seems others would, like to know more about the synchros. I wouldn't mind knowing where I can get some to store away like a squirrel with some acorns. Thanks again for a well written and timely post.
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Just to clarify -- my workaround was for the 4th gear OD switch on top of the gear case -- not the solenoid. The solenoid is quite easy to get to as it's on the bottom of the OD and near the back. All you need is a modified 25mm or 1" wrench or crow's foot. It's quite straight forward. And if you do need to remove the solenoid and don't want to drain the trans, jack the back end of the car up as high as possible to get as much fluid toward the front of the trans when you remove the solenoid. This will limit the fluid loss.
I think I mentioned in my other post that FCPGroton used to sell the synchros, but I don't see them on their website anymore. You might call them as they can do special orders for certain parts -- this may be one of them. What they had was probably SKF or ScanTech. I also checked with my dealer and the Volvo OEM stuff is $80 per synchro. I happened to have several dead gearboxes laying around, so I had a number of used ones to choose from. I did the first box several years ago with the Bentley manual and find that it's a fine digest for this service. There are 2 green books that cover the same thing. Biggest thing to remember is that the 3-4 gear selector ring has 3 teeth with slightly different beveling -- it's very subtle. The dogs go in there. If you don't line the dogs up properly when reassembling, you won't be able to shift.
When looking at used synchros, make sure that the teeth are not rounded and that there aren't deep grooves on each side (the teeth are triangular). You'll know what I mean when you look at them (it's from the synchros meshing with the gear teeth). Either can cause grinding. Also check the three slots on the inner ring where the dogs engage. If they are worn and misshapen (often you'll see that the slot has been elongated), the box either won't shift into the gear easily (synchros are not aligning the teeth properly) or it won't stay in gear (especially under deceleration). At least that's been my experience.
If you do the synchros, just give yourself plenty of time and keep a clean work surface. And be sure to bench-test the box before you put it back in the car. Better to fix a shifting problem now when it's easy to take it apart.
A depth gauge and calipers is handy for putting the shims back in. However, if you make sure that you keep everything in the same place (ie put the front intermediate shaft bearing race back in the front during reassembly), you shouldn't have too much trouble since you're not really changing the clearances.
Good luck. Cheers.
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Rally,
What are your thoughts on fitting a needle roller bearing with inner and outer rings from the input-shaft to main-shaft interface? My transmission parts have a LOT of clearance in this area and it really seems like a defective design.
Good note on the syncro-hub dog placement.
I scored new SKF Explorer Class ball roller bearings for the mainshaft and input shaft at $35 each. They were availible at Motion Industries. Is was said that the steel in these bearings is the finest they've ever made. Since the OEM price was $80 for bearings 40 years old, it was an easy choice.
Goatman
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I'm not a trans expert and I tend to treat the M45/46 boxes like AK-47's. (Beat them up, throw sand in them, and they still work). I've seen a few with 200-300k miles on them that didn't need much R&R -- seems like it's usually the OD that fails, then a synchro (the latter designed to be more of a wear part anyway), then maybe the input shaft bearing.
In my experience, the 4th gear synchro takes up the most slack and has the tightest tolerances between the input shaft and the main shaft. Doing what you're suggesting with a needle roller bearing sounds like it should be fine, but will require extra effort to get the right tolerances.
Thanks for the lead on the input shaft bearings.
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Rally,
The SKF 6306 NRC3 fits both output and input shaft. The part numbers are the same in the Volvo parts catalog. I know they look different, but the dimensions are the same.
N = with snap ring groove
R = with snap ring included
C3 = Running clearance greater then normal
The countershaft bearings are equivelent to Timken SET4 and SET14
http://www.unm.edu/~goatman/Augen.jpg
I torched open an input shaft bearing a few minutes ago hoping to see signs of shaft misalignment like I expected with the loose needle bearing fit. There were some signs but the steel was discolored from the heat. I have another subject that I will cut apart with the hacksaw tomorrow.
Goatman
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Goat,
I am glad to know that I am not the only one around.
I think if some parts are going away, they can do one more thing for me. Teach me something!
I tear open all kinds of things because it is entertaining and I get some revenge for that thing that became a problem child. Probably a good thing, I did not have any kids!
Hope you are kidding about using a torch or a hacksaw to split the bearings open.
I grind a groove deep on the one side or opposite each other. Use a hammer and a cold chisel to spread them a little. They do not spread. They will break open like a walnut or snap apart. They are as hard as a metal file or a threading tap.
I do the same thing to get inner races off a shaft. Again, same for the outer race, that is large enough to grind on the inside while still in a housing. Old bearings are fare game, if I cannot get any other kind of pulling method to work.
I try to inspect the grooves of races by using a magnifying glass and a bright light. I use the light behind the bearing and peek between the roller and balls. I look for flaking or pits on the balls or radius.
I save the rollers or balls for dropsy moments, angle seats and the measuring the amount of a taper in a bore.
Just thought a college boy like you, could appreciate that last tidbit.
Phil
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Machine,
I love to inspect those tapered bores. ;)
Could you tell me the average interference fit on a 1 inch diameter part?
Goatman
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Hi Goat,
I got to thinking about what you were asking. I gave you a general answer for an open-ended situational question.
Press fitting can change a little due to lateral surface area of the item pressed. I gave you .0002 as general machining rule of thumb for all press or “tight” fits. You can go up to .0005 per inch of diameter if the item is narrow in length. One inch is a small diameter like a bronze bushing or plain bearing.
I used .0002 as a rule of thumb. Because the most bearings I dealt with were upwards from four to five inches to as high as 24 inches on the outside diameter. Those are much longer. 24-inch diameter x .0002 still gives you a 0.0048 interference to a 0.012 tight fit if one uses .0005.
I should have said "minimum" in my last post for your 1.000 bearing. ID or OD you should always check a bearing and use that micrometer for best fit up when possible. Another thing you can do is check with the bearing house for specifications even though the “standards” were set, by the ASM, since like 1933, I think.
That was off the top of my head again.
We hope China uses them. Japan’s steel got better and then our equipment got better to make our steel cheaper (what little we make now), thanks to them! The Oxygen lance made a big difference.
Phil
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Phil,
Thanks for the info! Now I can sketch drawings for the machine shop.
Goatman
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Goat,
OH, I bet you do.
Some inspectors check tapers more than once to make sure that they got it to the right depth. Alignment and fit is everything for an easy and quality ensemble!
Yes. We usually shoot for size same size (referred to as metal to metal) and up to a maximum of .ooo2, that is tenths of one thousandth of an inch (for those not familiar with decimal digit placement) interference press fit per inch of diameter onto or into mating parts for bearing steel fits on most metallic materials. Excessive press can cause distortion of the bearing races that can cause premature failure due to excessive change in the running fit clearance inside the bearing.
You can find this information in older comprehensive bearing cross reference books and or sales catalogs.
In my early years, I learned many things working with some respectable engineers. Sort of like a technical adviser or liaison, between them and our shop capabilities. The company was flexible because it built factories from the ground up. We use to say “From paper clips to roof top” in country and abroad. We were an exporter, now it is all gone!
One of their slogans, which they shared with me, was “We are as good as our supply of reference books and a good engineer is as good as can use them”.
When they discarded the old books into some dumpsters, that I passed by routinely, I would dive in. I have read most and kept only a few. I had to change careers as our country changed! Luckily, I was alert enough.
Being curious and alert was a good fault I have stuck with.
Some might call it, the scratching and digging of a worker bee.
It literally was, a leg up!
Phil
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