65mph Sprinter Rpms With Gear

PLUMMER

New member
What are people running for rpms while at 65 mph with the 4.10 and 3.92 gears? Are the 3.92's really getting better fuel milage or do they operate at a lower rpm.From expirience this should be a 150 rpm difference, unless they have regeared the tranny to operate at smae rpm.
 

jdcaples

Not Suitable w/220v Gen
What are people running for rpms while at 65 mph with the 4.10 and 3.92 gears? Are the 3.92's really getting better fuel milage or do they operate at a lower rpm.From expirience this should be a 150 rpm difference, unless they have regeared the tranny to operate at smae rpm.
Welcome to the forum! You've outlined one of the mysteries.

My April 2007 order included the 3.92 rear axel. The estimated delivery date is October 2007.

I've never seen one in person. You found one in 1500+, right? At least I'm not completely alone in my selection :)

-Jon
 

ctmcdaniel

Cross Member
I too am a proud member of the "ordered a 3.92 but don't have my sprinter yet club". I don't have a Delivery date.

Tom
 
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jdcaples

Not Suitable w/220v Gen
I too am a proud member of the "ordered a 3.92 but don't have my sprinter yet club". I don't have a Delivery date yet.

Tom
Well lock me in Utah bunker and make me sweat rigid, 4-inch type L!

Congratulations Tom!

-Jon
 

Altered Sprinter

Happy Little Vegemite
I have a book on the axles somewhere in the book dungeons of actual books, surprise I do read letters by the page. In a nut shell the lower the gear ratio the higher the torque delivered at the rear axle,the higher it goes the less torque delivered to the rear axle , but higher the ratio the greater the pulling load as to the number of teeth to an axle. The difference is subtle, but noticeable from a standing start under load, less wheel spin basically. Whennthe class weights for loads change from 4.2 t onwards this is when the differences become more obvious.
I'll look for the book
Richard
 

ctmcdaniel

Cross Member
Well lock me in Utah bunker and make me sweat rigid, 4-inch type L!

Congratulations Tom!

-Jon
Jon

4 inch L would be rigid, or one huge roll, I would rather do it in Victualic.

sray.jpg

With out a Vin and stuck in D status.

Oh yeah were not NCV3 in USA were VB......



Tom
 

Altered Sprinter

Happy Little Vegemite
Jon

4 inch L would be rigid, or one huge roll, I would rather do it in Victualic.

View attachment 2442

With out a Vin and stuck in D status.

Oh yeah were not NCV3 in USA were VB......



Tom
Your not getting our VB! Go find another Victualic brand:laughing:
vb.JPG
Richaaaaaaaaaaaaaaaaaaaaaaaaaaaaaard! Hic!
 

jdcaples

Not Suitable w/220v Gen
Jon

4 inch L would be rigid, or one huge roll, I would rather do it in Victualic.

View attachment 2442

With out a Vin and stuck in D status.

Oh yeah were not NCV3 in USA were VB......



Tom
yeah, i started with one inch, but got ambitious after remembering an account of fire suppression plumbing in a safe house underneath utah and forgot to delete the "rigid."

anyway, it's time to get out of the bunker and join the rest of the world, even if dcx and mbusa are against it.

NCV3.

-jon
 

jdcaples

Not Suitable w/220v Gen

Attachments

jdcaples

Not Suitable w/220v Gen
your order report...
Tom

PD3?

Isn't that the glossy-brochure, silver-metalic, almost $1000 MSRP paint job?

Another member of this site was bemoaning that his wife loved *that* color and it was one of the more spendy paint options.

Good for you, Tom!

-Jon
 

ctmcdaniel

Cross Member
Don't be hateing on my paint, Bill...

Plummer.. My local dealer pre ordered some of the 3.9er's. He should have delivery dates by next week.

Tom
 
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PLUMMER

New member
:crazy: This is one hijacked thread.
I'll say......... not even 1 stat .rpm spec or otherwise. 3.92 being the taller larger or higher gear and 4.10 being the lower gear ratio. 1 dealer I spoke with said they had some older units with 3.42-3 and a 3.72 differential. Hmmmmmm, so does 1750 rpms at 65 mph sound right. it was one off the wall coment from dealer.
 

jdcaples

Not Suitable w/220v Gen
I'll say......... not even 1 stat .rpm spec or otherwise. 3.92 being the taller larger or higher gear and 4.10 being the lower gear ratio. 1 dealer I spoke with said they had some older units with 3.42-3 and a 3.72 differential. Hmmmmmm, so does 1750 rpms at 65 mph sound right. it was one off the wall coment from dealer.

Assuming

'07 tire size: 245 75 R 16 - overall diameter: 30.47

Final (fifth gear) Transmission ratio: .83:1

Axle: 3.92
I calculate it as:

1750 RPM = 48.776099295139744

2360 RPM = 65.77805390658845

Sources:

http://www.csgnetwork.com/speedcalc.html
(the math)
http://www.discounttire.com/dtcs/infoTireMath.dos
(tire measurement for 245/75 R16)
http://www.techauthority.com on line service manual content
( transmission definition )

-Jon
 
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ctmcdaniel

Cross Member
Plummer

Show your work, I read the NAG ouput ratio's some where in here this week. You could pull this togther.

I can't the math would make my head hurt.


Tom
 

Altered Sprinter

Happy Little Vegemite
Well just to throw a spanner into the works, I took my DW to the airport this morn 5 am Yuk! managed to send her off to N Zealand for a week:bounce:
With a 4.111 rear axle ratio at 65 MPH it sat on 2750 rpm not a happy sprinter in this torque range, the dam thing just wants to keep going to 3000 rpm to settle in at 75 miles per hour hits the magic ton at 3600 RPM and it still has a few HP to spare , but it's puffing for the last of whats left in the power band of no return, NOTE: Manual trans.
Richard
 

PLUMMER

New member
Well, I took out a 2007 170WB with 4.10 axle. It ran 2550 to 2570 rpms @ 65 mph or 103 KMH. Van being empty, it was WAY faster than my 6.5 GMC turbo diesel and any gas engine van I have. So anyone know what the 3.92 axle rpms are ?????? I am trying to find one to test. I wonder what rpm the CRD is most happy cruising at.
 

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