Tweak speedometer and/or shift points after regear
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Mountain Pass
Joined: Sep 2019
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Tweak speedometer and/or shift points after regear
As a followup to a previous note, I have started looking into doing a regear of ring/pinion from 3.55 to 4.10 in my E150 cargo van with 4.6L, 4R75E and 8.8" diff.
Checking with local shops has provided me with differing opinions on potential problems:
1. One shop stated that speedo and shift points will be fine because speedo gets its input from ABS sensors on axle shafts, so although the drive shaft will be at higher RPM, the axle shafts will still turn the same RPM (for a given vehicle speed), so the regear will present no problems.
2. One shop stated that PCM uses engine RPM, turbine speed, output speed, and vehicle speed to calculate shift points and the regear may present problems with shift points (still want to shift at same vehicle speed, but that will be at the now higher engine RPM caused by regear, so all shifts will be very late?).
Any guesses on if either of the above are true, and if #2 is true, is there a fix (for both speedo and/or shift point issues)?
Checking with local shops has provided me with differing opinions on potential problems:
1. One shop stated that speedo and shift points will be fine because speedo gets its input from ABS sensors on axle shafts, so although the drive shaft will be at higher RPM, the axle shafts will still turn the same RPM (for a given vehicle speed), so the regear will present no problems.
2. One shop stated that PCM uses engine RPM, turbine speed, output speed, and vehicle speed to calculate shift points and the regear may present problems with shift points (still want to shift at same vehicle speed, but that will be at the now higher engine RPM caused by regear, so all shifts will be very late?).
Any guesses on if either of the above are true, and if #2 is true, is there a fix (for both speedo and/or shift point issues)?
Thread Starter
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Mountain Pass
Joined: Sep 2019
Posts: 246
Likes: 110
Tires are just passenger tires, 235x70xR16, so lowish profile.
If my calculations are correct, the 4.10s would put me at about 2300 rpm, which is the Goldilocks rpm for my needs with this light trailer:
2006 E150:
TIRES: width = 235.0, ratio = 70.0, rim = 16.0, diameter = 29.0
3.55: 60mph (3rd) rpm = 2473, 60mph (OD) rpm = 1731, 70mph (OD) rpm = 2020
3.73: 60mph (3rd) rpm = 2598, 60mph (OD) rpm = 1819, 70mph (OD) rpm = 2123
4.10: 60mph (3rd) rpm = 2856, 60mph (OD) rpm = 1999, 70mph (OD) rpm = 2333
(when towing, I generally drive 65-70)
If my calculations are correct, the 4.10s would put me at about 2300 rpm, which is the Goldilocks rpm for my needs with this light trailer:
2006 E150:
TIRES: width = 235.0, ratio = 70.0, rim = 16.0, diameter = 29.0
3.55: 60mph (3rd) rpm = 2473, 60mph (OD) rpm = 1731, 70mph (OD) rpm = 2020
3.73: 60mph (3rd) rpm = 2598, 60mph (OD) rpm = 1819, 70mph (OD) rpm = 2123
4.10: 60mph (3rd) rpm = 2856, 60mph (OD) rpm = 1999, 70mph (OD) rpm = 2333
(when towing, I generally drive 65-70)
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Mountain Pass
Joined: Sep 2019
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Thanks Mark. Your vast experience in this area is a real asset to this list.
FTE Legend
Joined: Jun 2006
Posts: 31,930
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From: Ottawa, Ontario
My last two vans have the 4.6/4R75/4.10 powertrains with 245/75R16 tires and I think this is the ideal combo for this motor. The van cruises comfortably in OD on the highway and it won't drop out of OD until the grades get significant, it still gets decent fuel milage at 70mph but it drops noticably the faster you go beyond that.
Frmr Ford Trans Engr
Joined: Aug 1999
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From: SE Florida
That's right.
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i ain't rite
Joined: Mar 2005
Posts: 65,507
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From: Marlboro Mental Hospital.
it a way they were both rite.
newer vehicles read off the sensors on the axles, so shop 1 is correct for your vehicle. .
older vehicles go off the speedometer cable on the back of the trans, so shop 2 would be correct for my 1988 diesel pickup.
newer vehicles read off the sensors on the axles, so shop 1 is correct for your vehicle. .
older vehicles go off the speedometer cable on the back of the trans, so shop 2 would be correct for my 1988 diesel pickup.
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Moderator
Joined: Jul 2011
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From: Sioux Falls Area
Tires are just passenger tires, 235x70xR16, so lowish profile.
If my calculations are correct, the 4.10s would put me at about 2300 rpm, which is the Goldilocks rpm for my needs with this light trailer:
2006 E150:
TIRES: width = 235.0, ratio = 70.0, rim = 16.0, diameter = 29.0
3.55: 60mph (3rd) rpm = 2473, 60mph (OD) rpm = 1731, 70mph (OD) rpm = 2020
3.73: 60mph (3rd) rpm = 2598, 60mph (OD) rpm = 1819, 70mph (OD) rpm = 2123
4.10: 60mph (3rd) rpm = 2856, 60mph (OD) rpm = 1999, 70mph (OD) rpm = 2333
(when towing, I generally drive 65-70)
If my calculations are correct, the 4.10s would put me at about 2300 rpm, which is the Goldilocks rpm for my needs with this light trailer:
2006 E150:
TIRES: width = 235.0, ratio = 70.0, rim = 16.0, diameter = 29.0
3.55: 60mph (3rd) rpm = 2473, 60mph (OD) rpm = 1731, 70mph (OD) rpm = 2020
3.73: 60mph (3rd) rpm = 2598, 60mph (OD) rpm = 1819, 70mph (OD) rpm = 2123
4.10: 60mph (3rd) rpm = 2856, 60mph (OD) rpm = 1999, 70mph (OD) rpm = 2333
(when towing, I generally drive 65-70)
I'd agree, with that size tire the 4.10's look to be about the sweet spot. I had an explorer that used that size tire and with 3.73 gears it felt like an animal with the old 302 v8. adding a little more gear for a bigger vehicle and the 4.6 which makes a little less low end torque makes a lot of sense.
if you had significantly taller tires like the F150's (265/70r17's), that's where the 4.30's tend to be a better choice.
here is what i came up with for RPM expectations with your proposed combo. very close to what you calculated.
Thread Starter
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Mountain Pass
Joined: Sep 2019
Posts: 246
Likes: 110
Yeah, those tires are quite a bit smaller than what you see on the current F150's and that makes quite a bit of difference.
I'd agree, with that size tire the 4.10's look to be about the sweet spot. I had an explorer that used that size tire and with 3.73 gears it felt like an animal with the old 302 v8. adding a little more gear for a bigger vehicle and the 4.6 which makes a little less low end torque makes a lot of sense.
if you had significantly taller tires like the F150's (265/70r17's), that's where the 4.30's tend to be a better choice.
here is what i came up with for RPM expectations with your proposed combo. very close to what you calculated.
I'd agree, with that size tire the 4.10's look to be about the sweet spot. I had an explorer that used that size tire and with 3.73 gears it felt like an animal with the old 302 v8. adding a little more gear for a bigger vehicle and the 4.6 which makes a little less low end torque makes a lot of sense.
if you had significantly taller tires like the F150's (265/70r17's), that's where the 4.30's tend to be a better choice.
here is what i came up with for RPM expectations with your proposed combo. very close to what you calculated.
Moderator
Joined: Jul 2011
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From: Sioux Falls Area
I’ve posted it up here a few times to share. I can upload it tomorrow for you if you would like. Nothing special, but it’s got lots of different gear ratios in there for lots of different transmissions.
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Mountain Pass
Joined: Sep 2019
Posts: 246
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Yeah, that'd be great nerdy fun. Thanks!
Moderator
Joined: Jul 2011
Posts: 6,509
Likes: 662
From: Sioux Falls Area
here is the spreadsheet i use when i want to dork around with gearing and tire sizes.
the spreadsheet kind of started off figuring out what gears would be needed to maintain a similar RPM when you change tire sizes, and it kind of morphed from there into what it is.
the tire size up above is required, and both new and old sizes are required even if you aren't changing sizes. in that case, just make them the same.
but if you want to see the effect that a different tire size would have on your cruising RPM, just enter in the new size and let it eat.
happy nerding.
the spreadsheet kind of started off figuring out what gears would be needed to maintain a similar RPM when you change tire sizes, and it kind of morphed from there into what it is.
the tire size up above is required, and both new and old sizes are required even if you aren't changing sizes. in that case, just make them the same.
but if you want to see the effect that a different tire size would have on your cruising RPM, just enter in the new size and let it eat.
happy nerding.
Thread Starter
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Mountain Pass
Joined: Sep 2019
Posts: 246
Likes: 110
Well, rats.
Regear to 4.10 is complete. I am very happy with the new gearing. It adds about 300rpm at highway speed which is just perfect for my needs.
Unfortunately, the speedometer is now off. There are GPS speedometers (or phone apps) that I can use to tell me the accurate speed, but I still can't avoid a second or two of "Oh $#!+" when I glance down at the old speedometer and it tells me I'm doing a little over 80 when I'm actually doing the speed limit of 70. As a temporary fix, I put a towel on the dash and hung it over the front edge to block my view of the old speedometer. Still annoying, but not quite as bad.
I'm looking into tuning options, but to my surprise, there are very few tuning options available for E150 vans. I might end up posting a question or two over on the tuning forum on this site, but before then, I'll ask the transmission experts here one last question:
Is there any way i can disable the factory speedometer? I'd rather have it read zero than a value that is off this much. Is there a fuse I can pull or snip a wire to just disable the darned thing?
Rats.
Regear to 4.10 is complete. I am very happy with the new gearing. It adds about 300rpm at highway speed which is just perfect for my needs.
Unfortunately, the speedometer is now off. There are GPS speedometers (or phone apps) that I can use to tell me the accurate speed, but I still can't avoid a second or two of "Oh $#!+" when I glance down at the old speedometer and it tells me I'm doing a little over 80 when I'm actually doing the speed limit of 70. As a temporary fix, I put a towel on the dash and hung it over the front edge to block my view of the old speedometer. Still annoying, but not quite as bad.
I'm looking into tuning options, but to my surprise, there are very few tuning options available for E150 vans. I might end up posting a question or two over on the tuning forum on this site, but before then, I'll ask the transmission experts here one last question:
Is there any way i can disable the factory speedometer? I'd rather have it read zero than a value that is off this much. Is there a fuse I can pull or snip a wire to just disable the darned thing?
Rats.
i ain't rite
Joined: Mar 2005
Posts: 65,507
Likes: 5,563
From: Marlboro Mental Hospital.
no. the trans needs speedometer signal to work.
it is fairly easy to recalibrate the speedometer with forscan or autoenginuity.
i am sure there are other easy ways to do it too.
it is fairly easy to recalibrate the speedometer with forscan or autoenginuity.
i am sure there are other easy ways to do it too.
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