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Yet another G80 into a 240 thread

swiftjustice44

Central Coast Brickyard
Joined
Feb 12, 2007
Location
DALLAS
OK. I have the G80 out of a 91 740T w/ 3.73 1041 and ABS tone ring. I want to put into my 89 240 w/ a 1030, also a 3.73. I've read as many of the prior threads as I could. Still have some questions. From my reading, it seems no one changes the pinion gear. It's my understanding that ring gears and pinion gears are matched sets. Is no one getting any whining or other issues? Also, will cutting out three teeth to reduce the tone gear count from 48 to 12 really work? I measured the gap on the non ABS tone ring and the gap is roughly 3/4 inch but measuring between 4 of the ABS slots is about an inch and it's obvious the diameter of the ABS tone ring on the G80 is larger. One revolution is one revolution, I know...but is it really that simple?
Also, it's my understanding the 240's passenger side axle needs to be shortened...but how much? Kenny's article from a few years ago said 4mm but a recent thread mentioned 1/2 inch.
This rear end is going into my 80GT eventually. It has a 3.91 that I'd really like to use. Originally, I had thought I'd just use a mechanical speedo (I'm swapping in LH2.4 and the newer dash) but I've learned the speedo pulse goes from the speedo to the ecu. Does anyone know for sure what the ecu needs it for? Is it just cruise control or something equally benign like a shift light? If I could use the 3.91 I'd be faced with false speedo readings for sure. But...if the ecu doesn't need the signal for fueling then I could use the 3.91 w/o a tone ring and run a cable speedometer.
Any knowledge greatly appreciated.
 
OK. I have the G80 out of a 91 740T w/ 3.73 1041 and ABS tone ring. I want to put into my 89 240 w/ a 1030, also a 3.73. I've read as many of the prior threads as I could. Still have some questions. From my reading, it seems no one changes the pinion gear. It's my understanding that ring gears and pinion gears are matched sets. Is no one getting any whining or other issues?
'89 240 came with a 1031, not a 1030. 1041 and 1031 (same size) have a bigger ring & pinion than a 1030.

You would remove the open diff, remove the ring gear from the open diff, remove the ring gear from the G80, bolt on the ring gear from the open diff to the G80, then reinstall the G80 to the 240 axle housing.

Also, will cutting out three teeth to reduce the tone gear count from 48 to 12 really work? I measured the gap on the non ABS tone ring and the gap is roughly 3/4 inch but measuring between 4 of the ABS slots is about an inch and it's obvious the diameter of the ABS tone ring on the G80 is larger. One revolution is one revolution, I know...but is it really that simple?
Yes. If one ring is a larger diameter than the other, then the gap between the bars will be greater on the larger ring even if both have 12 bars.


Also, it's my understanding the 240's passenger side axle needs to be shortened...but how much? Kenny's article from a few years ago said 4mm but a recent thread mentioned 1/2 inch.
Most mention 1/4" which is about 6mm. 4mm would probably be OK. I think 1/2"(12.7mm) would be more than is required. I'm going to cut 1/4".
 
Thanks for the heads up. Of all my Volvos, the 89 is the only one missing an axle label. And I don't know what I was thinking...of course I'd re-use the original ring gear. Brain fart! Have any idea what use the speedo signal is to the ecu?
 
Have any idea what use the speedo signal is to the ecu?

it is not needed for any kind of fueling/engine control. if you want it to operate the speedo then you must chop out 3/4 of the tabs and install into the 240 using the later model diff cover/sensor, as you knwo.

also - the gap is irrelevant - you are measuring angular velocity ... therefore a point on the larger ring rotates FASTER than a point on the smaller one ... i.e. if they both have 12 evenly spaced triggering edges then they both will trigger identically at a given rpm, the distance between the triggers is dependent on the diameter of the ring ... you know what i mean? also i chopped off ~.5 cm from the right side and it was sufficient.
 
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it is not needed for any kind of fueling/engine control. if you want it to operate the speedo then you must chop out 3/4 of the tabs and install into the 240 using the later model diff cover/sensor, as you knwo.

also - the gap is irrelevant - you are measuring angular velocity ... therefore a point on the larger ring rotates FASTER than a point on the smaller one ... i.e. if they both have 12 evenly spaced triggering edges then they both will trigger identically at a given rpm, the distance between the triggers is dependent on the diameter of the ring ... you know what i mean? also i chopped off ~.5 cm from the right side and it was sufficient.

Super...good to know. I've cut the teeth off the tone ring. Will swap ring gears Monday.
 
I pulled apart the G80 today and cut the weight. REALLY easy. The stack of clutch plates comes right out with the gear under it. Then just pull out the shaft with the weight, cut it, reassemble, done. Took maybe an hour. Need a can of brake cleaner, some gloves, rags or paper towels, T-25 torx and maybe a plastic coated dead blow, bench vise (optional), and cutoff wheel on a grinder. This is just to modify the G80, not to install in an axle.
 
I'm considering cutting off the rest of the weight. Mine looked a little different than Matt's...

124312870.jpg


http://forums.turbobricks.com/showpost.php?p=598206&postcount=13

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I'll tear into mine tomorrow. I'm doing the conversion on my 89 245. Assuming everything goes well, then the entire axle can transfer into my 80GT.
 
it is not needed for any kind of fueling/engine control. if you want it to operate the speedo then you must chop out 3/4 of the tabs and install into the 240 using the later model diff cover/sensor, as you knwo.

also - the gap is irrelevant - you are measuring angular velocity ... therefore a point on the larger ring rotates FASTER than a point on the smaller one ... i.e. if they both have 12 evenly spaced triggering edges then they both will trigger identically at a given rpm, the distance between the triggers is dependent on the diameter of the ring ... you know what i mean? also i chopped off ~.5 cm from the right side and it was sufficient.

Not so. The speed signal is essential for LH 2.4. Read GroupA's thread about the wild idle after coming off throttle on a LH 2.4 system that does not have the speedo signal. Plenty of members here have had the same problem.
 
Not so. The speed signal is essential for LH 2.4. Read GroupA's thread about the wild idle after coming off throttle on a LH 2.4 system that does not have the speedo signal. Plenty of members here have had the same problem.

ah, i dig.
it occurs to me i assumed it was not needed because mine was uneffected, but it occurs to me that by the time i did this i already had megasquirt :oops:

well, he should definitely get the 1041 cover and plug the sensor in (with missing teeth) then i suppose.
 
Not so. The speed signal is essential for LH 2.4. Read GroupA's thread about the wild idle after coming off throttle on a LH 2.4 system that does not have the speedo signal. Plenty of members here have had the same problem.

This is good to know. I knew the signal goes to the speedo as a pulse and the speedo converts the signal and sends it on to the ecu; just did not know the purpose. Now that I've converted my tone ring from 48 to 12 teeth, I'll install it tomorrow and make sure all is well.
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PICT0001-6.jpg
 
OK...cleaned up all the little nubs left by the Dremel, cleaned the locker up and installed it in the carrier. Cut 1/4" off the passenger axle, fit perfectly. Installed the 740 cover plate since I figured the clearance would be correct. Filled it up w/ grease and went for a test spin. The good news is the locker works GREAT! The not so good news is my speedometer is acting the same way yamahapro was describing in his thread. At slow speeds, the speedo does not bounce but I think it's reading a little high. When I get up to 30 (so it says) the needle starts sweeping between 30-40. Speed up a little more, the sweeps become more extreme. I thought perhaps the carrier in the 1031 might not be as deep as the 1041 and was picking up the sides of the ring so I shimmed the sensor out 1.2mm Identical results. Yamahapro said he swapped his wires in the speed sensor connector and solved the issue. I ran out of time to try this today but don't see how it could affect anything. I didn't have the connector apart at any point.
Anyone have any ideas? Oh, the speedo was fine prior to the swap...
PICT0008-5.jpg
 
Well, a quick update on the speedo issue. After re-reading yamahapro's thread where he said he flip flopped the sensor leads, I figured, what do I have to lose? So, first I removed the duplex connector and installed the leads onto the 1041 sensor, leaving them in the factory position. No change, although I did notice that when I went into overdrive the speedo stabilized temporarily. Raised car back up, swapped the leads, lowered it down and fired it up. Speedo performed flawlessly. Put duplex connector back onto the leads, locked it into the sensor. Tried it again to be sure...speedo is cured. I have no clue why a pulsed signal would do this unless there is some sort of one way diode up front. My car is an 89 originally equipped w/ an AW70. Who knows? Anyway, now it's ready to get swapped into the GT, so that's a good thing!!
 
Are clutch packs for these available from anywhere? Dealer item?

My G80 doesn't do diddly squat, before just tossing it on the scrap heap and going with a TT I figured I'd try some new clutch plates if theyr'e available.

And I'll def. cut the flyweight off while it's apart too.
 
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