AWD vs FWD final drive ratios
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    1. #1
      Global Moderator tmtalpey's Avatar
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      AWD vs FWD final drive ratios

      Volvo specs say that the 2006 S40 and V50 T5 FWD models have a different final drive ratio from the AWD. 3.77: in the FWD and 4.00:1 AWD.

      However, the 2005 specs show 3.77:1 all around, and I am a skeptical person. AWD weighs only 130 lbs more than FWD, that's nowhere enough to warrant the large ratio change.

      So I propose a test. Someone with a 2006 V50 T5 6MT FWD and a stock tire size drive the car steadily at 45mph in 4th gearand get the tachometer reading as closely as possible. I will do the same in my 2005 AWD and we'll see.

      For completeness I'd be interested in the same results with V50 T5 2005 FWD, and of course S40 as well. But no need for 2.4i runs, they have different transmissions and ratios.

      If the ratio is 3.77:1, the tach will read 2475rpm. If it's 4.00:1, the tach will read 2625.

      Interestingly (to me, anyway) the GT has very similar overall ratios, at least based on the 3.77:1 figures. I posted about them a while back here: https://forums.swedespeed.com/zerothread?id=33779

      Post your results! I will run my test tomorrow morning.

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva Forge CBV, Elevate rear swaybar and torque mount, Snabb shift kit, etc.
      2016 XC60 T6 AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

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    3. #2
      Junior Member Seven's Avatar
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      In the name of science, I tried this tonight:

      2006 S40 T5 AWD MT: going 45 mph in 4th gear the tachometer was approximately 2400. The roads were not perfectly flat, but close enough I think. Hope this helps.


    4. #3
      Member djeremya's Avatar
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      Re: AWD vs FWD final drive ratios (tmtalpey)

      It's getting close to 20 degress tonight = I'm gonna take out the car for a spin .. heh heh. Will let you know as soon as I get back.
      '13 XC90, '08 XC70, '05 S40 T5AWD M, '05 S60R M, '04.5 S40 T5 A, '03 XC90, '01 S40, '95 850 GLT 2.5

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    6. #4
      Global Moderator tmtalpey's Avatar
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      Re: AWD vs FWD final drive ratios (tmtalpey)

      2005 V50 6MT AWD: 2440rpm @ 45mph.

      Only 35rpm off the predicted value of a 3.77:1 final drive with stock tire size. I used an OBD link to get precise values btw.

      Pretty much exactly the same as Seven's 2006 S40... I think this proves that the 06 S40 isn't 4.00:1. But let's see more data!

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva Forge CBV, Elevate rear swaybar and torque mount, Snabb shift kit, etc.
      2016 XC60 T6 AWD
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    7. #5
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      Re: AWD vs FWD final drive ratios (tmtalpey)

      Let's try it @90 mph as this will decrease reading error by 50 % (although may increase speeding ticket by 200 %) we could also tear apart out transmissions and count the teeth. ,

    8. #6
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      Just to compare:
      '05 S40 T5 FWD 6-spd
      45 mph around 2200 rpms in 4th gear
      SOLD: '05 T5 AWD GT, stock

      SOLD: '05 T5 FWD 6-spd, IPD sway bar, IPD HD TCV, MS3 struts & rear sway bar end links, bilstien shocks, IPD front sway bar end links, ebay downpipe, magnaflow muffler, Elevate tune, 18" Medusas

    9. #7
      Global Moderator tmtalpey's Avatar
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      Re: (Silver T5)

      Quote, originally posted by Silver T5 »
      45 mph around 2200 rpms in 4th gear

      Now that's interesting. Assuming the tires and gearbox are the same, this would be a 3.35 final drive. You're sure that wasn't two hash marks above 2000?

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva Forge CBV, Elevate rear swaybar and torque mount, Snabb shift kit, etc.
      2016 XC60 T6 AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    10. #8
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      Re: (tmtalpey)

      Yes, interesting.
      2300 RPM for my 2005 T5 6MT. I measured it twice & was careful to make my line of sight perpendicular to the tach surface, so I think I'm certainly within 50 rpm of what my gage says.

      I have winter tires, but this shouldn't matter, correct?
      I can't believe the speedometer measures actual vehicle speed, but rather the rotational speed of some part (the transmission output shaft, ie the half-shafts, or the ABS wheel [rotation] speed signal?).
      So, don't the tach & speed values just give the relative rates of these two parts, independent of vehicle speed - in which case tire diameter shouldn't be affecting the relative values of tach & speedometer. For example, with smaller tires the vehicle is going slower, but the speedometer doesn't know it.
      Does this make sense?
      And then, why are we getting such a large spread in values?

      Edit: Mine is FWD, S40. And, yes, needle was precisely 1 and 1/2 hash marks above 2000RPM


    11. #9
      Member djeremya's Avatar
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      Re: AWD vs FWD final drive ratios (tmtalpey)

      Mine's right on the two hash marks above 2 RPM. 45mph, 4th gear, 2400 RPM

      T5 AWD 6spd, 205/50/17.

      '13 XC90, '08 XC70, '05 S40 T5AWD M, '05 S60R M, '04.5 S40 T5 A, '03 XC90, '01 S40, '95 850 GLT 2.5

    12. #10
      Global Moderator tmtalpey's Avatar
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      Re: (steve909)

      Quote, originally posted by steve909 »
      I have winter tires, but this shouldn't matter, correct?
      I can't believe the speedometer measures actual vehicle speed, but rather the rotational speed of some part (the transmission output shaft, ie the half-shafts, or the ABS wheel [rotation] speed signal?).

      Actually it might, depending on how different the tires are from stock. Tire Rack has specs for revs/mile of each of their tires, maybe you can look yours up?

      In any case, the speedo is in software, it works off the wheel revolution reporting from the BCM (brake control module) and computes speed from a programmable setting in the car, which was set at the factory based on the stock tires. So if your snows have thicker tread leading to a thicker diameter, I would expect the tachometer to read low for a given reported speed.

      I haven't seen any high reports here, indicating to me that none of these cars has a 4.00:1 final drive.

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva Forge CBV, Elevate rear swaybar and torque mount, Snabb shift kit, etc.
      2016 XC60 T6 AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    13. #11
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      Re: (tmtalpey)

      Tom,

      A steady speed of 45 mph on a level surface suggests to me that the S40/V50 AWD would be operating in 100% FWD mode. Would engagement of the AWD system change the final drive ratio?


    14. #12
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      Re: (Calhon)

      I'm not Tom but NO this won't . Final Drive is just that, the final gear going from trans to eng. I can see with a CVT set up with sudden engagement of an awd change of final but not with us.

    15. #13
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      Maybe I missed something, but it looks like the AWD is carrying the higher RPM, regardless of the model year.

      Maybe the misprint was in the '05 specs, and all AWD's have the 4.00 gearing, with all FWD's having the 3.77


    16. #14
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      Re: (dneal)

      yeah, I think the europeans also have a 2.85 ratio for the 2.0 D. wonder what the 185 hp D5 will get?

    17. #15
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      Re: (Volvo_girl)

      We've actually been running through all the different ratios ourselves for our new racecar (which will be FWD). FWD is 3.77:1 and AWD is 4.00:1 in all S40's, and if I'm not mistaken, I believe that runs through all the years. Our racecar will have higher ratios.

      JR


    18. #16
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      Re: (prodriver)

      Prodriver may have the definitive information. But, all the data reported thus far supports this.

      3.77 is 5.75% less than the 4.00 ratio.
      The FWD owners (all two of us!) are reporting 2250 RPM (average), the AWD owners reporting a bit over 2400. The difference between these two is 150RPM, or about 6%.
      This says the FWD has lower ratio hardware than the AWD.

      Using TireRack's 834 Rev/mi for the Mi 205/55R17 Pilot MXM4 (not my tire, TireRack didn't have Rev/mi. for my tires - my 17" OE Michelins nor my 205/55R16 Blizzak snows), for 45 mph gives a ratio of 3.68 - assuming 4th gear is a ratio of 1.00 (which I think is close, but as I remember it's a bit less than this - I can't find this info. just now).

      So, it seems the FWD has the ratio of 3.77 and the AWD of 4.00.

      Edit: Conclusion: the 2005 literature claiming 3.77 all around seems to be in error.


    19. #17
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      I double checked my rpms in 4th @ 45mph and it was slightly above if not dead on 2200 rpms. I have the Dynamic Trim with the 17s. Are the overall tire diameters the same?
      SOLD: '05 T5 AWD GT, stock

      SOLD: '05 T5 FWD 6-spd, IPD sway bar, IPD HD TCV, MS3 struts & rear sway bar end links, bilstien shocks, IPD front sway bar end links, ebay downpipe, magnaflow muffler, Elevate tune, 18" Medusas

    20. #18
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      Re: (Silver T5)

      You can figuare out the outside diameter of the tire using this formular.

      OD= tire width in mm x aspect ratio/12.7 then add the wheel dia.

      example OD of a 205 55 16 =24.88" 205 50 17 = 25.07" 225 45 17 = 24.97" and 225 40 18 = 25.09" so yes regardless of factory size. you will stay within 1 % of OD of each other. go from a 205 55 16 to a 235 40 18 (OD 25.4 ) and it would be like changing that 3.77 to a 3.69 (2% change)


    21. #19
      Global Moderator tmtalpey's Avatar
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      Re: (steve909)

      This turned out to be a very useful discussion!

      Answering a couple of posts here.

      1) Ratio doesn't change with engagement of AWD. It's the same at front and rear, and not variable in any way on our cars.

      2) The gear ratios, to the degree we can trust the details of Volvo's published specs, are available by drilling down into the year->model->specs pages at http://volvocars-pr.com. The 6MT 4th gear ratio is 0.95:1.

      3) I don't know what I did in my math, but I agree that the published 2005 Volvo specs are wrong (not the 2006), and the final drive must be 4.00:1 in the AWD's.

      Here's an analysis for my tires and a 3.77:1 final drive:

      Michelin Pilot Sport A/S 205/55-16: 823 revs/mile (specs)
      times
      45 miles/hour
      times
      3.77 final drive
      times
      0.95 4th gear
      divided by
      60 minutes/hour
      equals
      2210 engine rpm.

      OTOH for a 4.00:1:

      Michelin Pilot Sport A/S: 823 revs/mile
      times
      45 miles/hour
      times
      4.00 final drive
      times
      0.95 4th gear
      divided by
      60 minutes/hour
      equals
      2345 engine rpm.

      This is 95 rpm less than I observed, but clearly is the better match to the data. In fact, 95rpm is just about exactly 2mph, which is basically roundoff error.

      CONCLUSION:

      Now we know why the AWD suffers worse fuel economy from the FWD!

      In addition to the extra 130 lbs, and the increased drivetrain drag (though these are small)...

      It's the rpms. 6% higher rpm's means 6% more air going through the engine per mile and therefore 6% more gas. 6% of 25mpg is 1.5mpg right there.

      On the other hand, and putting my loony hat on, I can see why this is done.

      The main reason is likely the Haldex unit. If the final drive ratio is numerically lower, the taller gearing means the difference between wheel slip and traction is going to be small. This means the Haldex won't be able to detect it as quickly, or as certainly. It will be less effective. And, high input rpm's will give its oil pump more action.

      Second reason is probably takeoff. The AWD pulls with 4 wheels and therefore pulls down more torque. Getting the engine into the powerband earlier is a god match to this. And, an AWD driver is going to be looking for this.

      OTOH, the FWD is going to actually want less torque at first, in order to avoid chirp. But the longer gearing will make up for it and give it a better run.

      Jameson, I envy your ability to be able to evaluate the car both ways. Wish I could feel the difference first-hand!

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva Forge CBV, Elevate rear swaybar and torque mount, Snabb shift kit, etc.
      2016 XC60 T6 AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    22. #20
      Global Moderator tmtalpey's Avatar
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      Re: (tmtalpey)

      Another way of playing with the final drive ratio is to change the tires. In this case, an AWD driver might consider a taller tire. The goal would be to decrease the tire rotational speed by 6%.

      For my Pilot Sport A/S, I could drop the tire from my current 823 revs/mile to somewhere around 782 - a 235/50-17 would fit the bill nicely at 777. Of course, that means new wheels too. In 16's, a 225/60-16 goes to 770. Now those would show some sidewall.

      I wonder if it would be fun to try this...

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva Forge CBV, Elevate rear swaybar and torque mount, Snabb shift kit, etc.
      2016 XC60 T6 AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    23. #21
      Global Moderator tmtalpey's Avatar
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      Re: (tmtalpey)

      I seem to be having this discussion with myself but if up-diametering the tires makes any sense at all, it's obvious the car's electronics need to know about it. Especially for the GT trans and stabilty control, road speed is an important parameter. To say nothing of the speedo/odo of course.

      Besides, for all those AWD-rides-too-friggin-high types, it is a great way to fill up the wheel wells!

      Tom.

      2005 V50 T5 AWD 6MT w/Heico tune, Heico exhaust, Bell intercooler, IPD TCV, Viva Forge CBV, Elevate rear swaybar and torque mount, Snabb shift kit, etc.
      2016 XC60 T6 AWD
      1956 PV444 complete, running
      1956 PV444 very original, very rough

    24. #22
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      This thread is older than my car, but relevant to a question I was wondering about...

      Does anyone know where the transmission gear/final drive ratios are listed? I saw them a while back but can't remember where I read them. Pretty sure it was Volvo literature since it was the classic blue and white color scheme, but I can't seem to find it in my manual.
      2007 S40 T5 AWD

    25. #23
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      Interesting find. I installed 225/50/17s and it helped with the final drive ratio, but it's still relatively short. That being said, most awd cars have higher gear ratios. I'm guessing that's because you're more likely to be pulling something with it or needing the extra power in off-road situations. I've certainly been glad to have the extra power when doing some off-roading.
      2005 V50 T5 AWD M66

    26. #24
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      Found the gear ratios...if anyone else is curious, they're listed on the 2nd page:
      https://docs.google.com/document/d/1...rvya1SB04Y/pub
      2007 S40 T5 AWD

    27. #25
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      ^ hmm, is that chart implying that all AWD T5's came with the sport suspension?
      edit: my mistake, i read that wrong.
      Last edited by Brown9348; 12-24-2015 at 10:40 PM.
      05' S40 T5 AWD >129k miles. KW V1. E-focus tq Mount. Racing Beat rsb. SPC arms. 18"Midir's, 17" Pegs.
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    28. #26
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      Cross-posting for posterity...

      Interesting research over on the R forum, not to burst anyone's bubbles, but:

      Quote Originally Posted by apsyx View Post
      Ok guys, lately I did a bit of research on M66s and here's what I found: (Also thanks to theshadow27 for our meaningful discussion)

      TL;DR: If you are looking for a M66C, S60R/V70R is the only platform to source from. The M66s from S40/V50 T5 AWDs might bolt on, but they are NOT M66C.


      There are mainly two variants of M66 AWD transmissions out there (diesel gearboxes not considered here, nor M66D and M66Es as they seem never present in the US): M66C (M66CA21 to be exact) and M66W (M66WA33 to be exact)

      In the US, M66CA21 only comes in 04-07 S60R/V70R as we've already known, while M66WA33 comes from S40/V50 T5 AWDs. I verified this by querying all the S40/V50 T5 AWDs for sale that provide a VIN through a paid VIDA subscription (which supports querying the factory specs of any VIN from Volvo's database) and they all point to M66WA33.

      These two gearboxes look pretty much identical, however they have gears with different ratios. Part number for M66CA21 includes 8252140, 9482302, 9482343, 9482369, 9482417 (they all refer to the same part and are interchangeable, minus different shift levers). Part number for M66WA33 includes 8252157, 9482340, 9482368, 9482415, 9482424 (these are also interchangeable).

      Tag pics:



      Gear ratios:
      M66CA21:
      1st: 3.39
      2nd: 2.05
      3rd: 1.43
      4th: 1.09
      5th: 0.87
      6th: 0.70
      FDR: 3.77

      M66WA33:
      1st: 3.39
      2nd: 1.91
      3rd: 1.27
      4th: 0.95
      5th: 0.78
      6th: 0.65
      FDR: 4.00

      There seemed to be a belief that S40/V50 T5 AWDs were also equipped with M66C, however I find this not true and during my research I did not find any concrete evidence of a M66 box from S40/V50 T5 AWD showing M66CA21. (Refer to my above experiments with querying S40/V50 T5 AWDs' VIN to check for the gearbox equipped out from factory). I intend to conclude that no M66C was ever paired with S40/V50 T5 AWDs. I think the misconception is caused by folks thinking there's only one M66 AWD box out there and the box on S40/V50 T5 AWDs is indeed a M66 AWD (just it's not M66C). Also the fact the FWD cars equipped with M66s (M66WF23 to be exact, has same gear ratios as M66WA33, except for a FDR of 3.77) makes it further confusing if we just combine "M66 AWD box" with "3.77 FDR" to incorrectly assume a M66C.

      The Quaife LSD page seemingly also lists S40/V50 T5 AWD having M66C, which I believe is also due to the above misconception. But the LSD does fit on S40/V50 T5 AWD M66WA33, reason being the LSD is just to replace the original differential in the M66 box while retaining all its original gears (thus the gear ratios actually doesn't matter here, as long as the dimension for the differential is the same. In this LSD installation guide, note the step where the ring gear from the old differential is transferred to the new LSD).

      Hope this could clear the cloud a bit and I'd be happy to learn from you guys if any part is wrong!
      - https://forums.swedespeed.com/showth...97#post7496897

      I assume that the different Quaife's (13J vs 14J) are due to the different spline counts on the half-axels.
      '05 S40 T5 AWD M66 sport/winter/ew. Michelin PS A/S+. 6000k 50w HID low/HIR1 high/full LED conversions. RiCA SW. Evoelate intake. IPD rear sway, skidplate, TCV.
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    29. #27
      Junior Member apsyx's Avatar
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      Thanks Shadow. I think the difference on 13J and 14J is mainly due to AWD/FWD differences (An output component for angle gear in AWD diff vs none in FWD diff). Not sure about the spline counts though as I don't have them to compare.

      Quote Originally Posted by theshadow27 View Post
      Cross-posting for posterity...

      Interesting research over on the R forum, not to burst anyone's bubbles, but:


      - https://forums.swedespeed.com/showth...97#post7496897

      I assume that the different Quaife's (13J vs 14J) are due to the different spline counts on the half-axels.
      2006 S60R GT 106K Black Sapphire/Nordkap

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