m46 or m47

First of all, i beleive that this post is worthy of the performance board. If not please move it.

From what i have read in the past, I understand that the m46 is stronger than the m47. How much HP can the m47 hold? Also, is the m47 the same length(same driveshafts) as the m46. Probably not b/c of the OD. Please help. Thanks.

I've heard the M46 is the better option for higher HP engines. Case in point: They never put a M47 in a turbo charged model (to my knowledge).

According to a Volvo Technician I know, the M47 is a re-work of the M46 and when you "shift" to 5th gear, you are actually staying physically in 4th gear but moving the stick engages the O/D (instead of hitting the button).

So, the M47 is a considered among some circles as a "true" 5-speed, but I think it is actually a O/D based 5th gear.

I'd also like to know if anyone has additional info on the differences between the 2 trannies. Either way, M46 or M47......they'll be a heck of a lot more fun than a AW71!!!!

no, they actually did put m-47's in turbos

Well, Paul (volvula) has a m47 in his 245ti and he seems to think it's holding up fairly well, though I know he baby's it.

The m47 is much more a true 5 spd than you give it credit for. Just look at the cut-aways of both, oh ya and theres no external OD on that one!

No really, it has a whole other gear set built into the trany.

There were euro versions of the 780 turbo B-230FTI & B-234FTI that had the M47 behind them... Too bad we Yanks get the short end of the stick...

The first gear on the M47 is much lower too........

Andrew

2 780s said:

There were euro versions of the 780 turbo B-230FTI & B-234FTI that had the M47 behind them... Too bad we Yanks get the short end of the stick...

The first gear on the M47 is much lower too........

Andrew

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For once I think we actually got the better deal, because the m47's are far weaker, depending on how bad you thrash them, than a m46. Aren't the m47 all alloy cased?

Doug

I stand corrected on the M46/M47 issue. Didn't realize they put them in 240 Turbos. Never seen a 240 Turbo with out an O/D button. Same with the 700 series.

M47's were NEVER an option on 240T's, not even 740T's (at least not in North America). The fifth gear on the M47 is a true fifth gear, not just a different way of engaging the O/D. If you look at the two trannies side by side you'll see what I mean (the O/D is big and bulky).

Roguls
New York, USA

Roguls said:

M47's were NEVER an option on 240T's, not even 740T's (at least not in North America). The fifth gear on the M47 is a true fifth gear, not just a different way of engaging the O/D. If you look at the two trannies side by side you'll see what I mean (the O/D is big and bulky).

Roguls
New York, USA

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Yes they did. In 1987, and again breifly in 1991. I've seen an 87.

Here's a (my) M47, BTW:
http://www.geocities.com/p_demeo_2000/M47.html As you can see, the first secton is almost identical to that of an M46.... (and is still basically "added on") It is no weaker than a alloy M46 from a 740...

one question... isnt both the M46 and M47 based on the same 4 speed design, with just an O/D or fifth gear put onto the back half of the housing? it says something like that in Bentley, but i just wanted to ask...
Jimmy

Yeah basically.

There's at least about 3 different designs for the 4speed part (1 steel and 2 alloy designs that I know of) and then, from what i've seen of the early 5 speeds, the 5th gear is just simply that, a gear stuck on the back of the 4 spd gear box... instead of the - supposedly - less reliable OD...

My OD runs real nice... its kinda nice to have a auto top gear... flick the OD off and its off. Because mine's nice and firm, its like having a clutchless gearbox... sweet.

However there's nothing that beats a true 5speed, or 6 speed for that matter. The M47's that I've seen are realy just 4 speeders that have a 5th gear on the back. From what I've seen I'm not that surprised that they had poor oiling for the 5th but whadda I know?

For a NA application up to 200hp I'd say, a M47 is nice (make sure its properly filled eh?) and a NA or Turbo app up to 225-250hp a M46 that's in good shape will serve perfectly well. I personally think that the Supra or Celica tranny is quite sweet.

I dont understand a comment that was made earlier... about having a even shorter 1rst gear to make your car faster... I ask why???? Volvo 1rst gears are so annoyingly short!! Just tweak 2nd gear down a bit and you'd have a much better 1rst gear in my opinion... now if you had a low axle (3.31) or big wheels that's a different story, as I'm driving a small 195/70HR14 set of tires on 3.73 gears in my M46 4spd+OD 242GT...

Trannies are a funny thing.

2 780s said:

There were euro versions of the 780 turbo B-230FTI & B-234FTI that had the M47 behind them...

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Must have been the B204FT/GT because Volvo never made a 2.3L 16v turbo.


[quote:35536ea9e5]The first gear on the M47 is much lower too........[/quote:35536ea9e5]

They have the same 1st-4th ratios (4.03, 2.16, 1.37, 1.00) unless you find one from before about '82/'83.

Where would it say M46 or M47 on the tranny? Or is just looking for a OD button a reliable way to tell them apart?

guidom12345 said:

From what i have read in the past, I understand that the m46 is stronger than the m47. How much HP can the m47 hold? Also, is the m47 the same length(same driveshafts) as the m46. Probably not b/c of the OD. Please help. Thanks.

Click to expand...

I don't know how much power the M47 will hold because it's not a predictable transmission. I've heard many stories ranging from some that have died behind non-turbos in under 100k miles of normal use, all the way up to some that have held well over 200hp from a turbo, driven hard. If you use proper fluid and change it OFTEN (15-20K miles) and overfill, it should last a while. The M47 can suffer from poor lubrication, so try to get as close to 2L into it by jacking up one side of the car.

If you miss a shift with a high HP engine, I wouldn't expect the M47 to handle it very well. I've abused my M47 quite a bit with general hard driving and many crunched gears from trying to shift too fast, and it's still doing fine behind my B230F at 168K miles. It doesn't whine and it shifts the same as when I got it with 132K.

The M47 has a true 5th GEAR and synchro. It has no overdrive unit, no solenoid, no switch, no wiring, no relay like the M46 Overdrive transmission. Because it has no OD unit, the M47 is shorter and the front half of the driveshaft will be longer than that of an M46.

guidom12345 said:

Where would it say M46 or M47 on the tranny? Or is just looking for a OD button a reliable way to tell them apart?

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I was just looking through the Bentley manual, and it appears that you could tell the difference very quickly just by looking at the location of the drain plug. If it's near the front of the trans (front of car) and forward of the fill plug, it's an M46. If it's near the rear of the trans and reward of the fill plug, it's an M47. Having not looked at enough M46/47 transmissions, I couldn't tell you if this is consistant throughout the production run.

If it's still in the car with a shift lever attached, try shifting from 3rd to 5th gear. If you're pulling it from a junkyard, I would expect the shift knob is one of the first things to go, because I've seen a lot of bare shift levers that all look the same.

If there's an OD still attached, it's pretty easy to identify from a 4/5spd.

[quote:485e2ab213]Must have been the B204FT/GT because Volvo never made a 2.3L 16v turbo.[/quote:485e2ab213]


so what engine did they put the 16v turbo on?
:?:

Every volvo I have seen in the junkyard is missing the shift nob too! I havent found any manual turbo 740s yet so i am about to give up.

It was a 1.995 liter engine made in italy to keep them under the tax they have on high displacement engines. Chances of finding one of these in running condition in italy SLIM. Anywhere across the pond probably not at all. And tower was correct there has never been a 2.3 16v turbo production engine from volvo

We should put some of this stuff in the FAQs, seems we've debated this one quite a bit.

But, from my perspective, the M46 is plentiful and the steel case versions will take 250HP or so, and the OD ain't half bad. It's nice not to have to hit the clutch again, and they'll take abuse if well maintained.

However, the M47 is lighter (as is the alloy case M46) and you never worry about forgetting to turn the OD off when downshifting. No OD switch, relay, or solenoid to crap out. But - I don't think it will take as much power without some reinforcement. Paul - what did you do to yours to make it a M47'R'?

I think for most of us, the M46 is fine. Beyond that, what's cheaper - replacing your tranny on a regular basis or swapping in a Supra tranny?
This is where we're stuck untill Kenny finishes his T-5 swap kit. :wink:

and for those frustrated with Volvo shift knobs, I'm putting together a universal shift knob and an aftermarket switch. pics and details to come.