How high are your RPMs at 70mph?
07-26-2007, 07:54 PM
#18
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3.54's here ... and a 6 speed. Mine's right at 2,100 to 2,125 rpm at 70 mph in 6th gear. It's hard to say the rpm, because the tick mark intervals are stupid. 2,000 - 2,125 - 2,250 - 2,375 - 2,500 Instead of even 100 rpm increments! At least that's how it is on 2nd gen trucks.
In my truck, 2000 rpm is exactly 72mph.
jh
07-26-2007, 09:42 PM
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It's hard to say the rpm, because the tick mark intervals are stupid. 2,000 - 2,125 - 2,250 - 2,375 - 2,500 Instead of even 100 rpm increments! At least that's how it is on 2nd gen trucks.
07-27-2007, 07:12 AM
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07-27-2007, 08:11 AM
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...Off Topic, but whats the deal with the 3.54s? Did dodge offer 3.54s as well as 3.55s? I've got 3.55s(although i really wish I had 4.10 atleast) in mine and I haven't ever heard of 3.54s until I started coming on here and the Diesel section on DT. I was a previous 1500 owner and never saw 3.54s talked about even once...
Besides the fact that the 2500 and 3500 gears more robust, there is a negligible gear difference also.
The fact that so many guys come from having 1/2 ton trucks with 3.55 gears, that's just what they remember. But the fact is, your truck should actually have 3.54 gears. Somebody let me know if I'm wrong.
- JyRO
07-27-2007, 10:56 AM
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Thats what I was assuming after I started coming around here and getting into more 2500/3500 talk... I noticed most guys were saying they had 3.54s... so I assumed if I had the higher gears they'd be 3.54s. But I looked at the owners manual for the truck and on sticker listing the trucks options and what not it says 3.55 I'm pretty sure. I'll have to double check now to be sure.
07-27-2007, 03:15 PM
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07-27-2007, 04:09 PM
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3.54 vs 3.55:
The tooth counts for the D60 are 39/11, which equals 3.54545454545 etc.
Technically, you should round it up to 3.55, but some call it a 3.54
For rounding, you round a 5 up if the digit to the left is even, and down if it's odd. Since the 3.54 is even , the next 5 should be rounded up, giving you 3.55
There is no difference between a 3.54 or 3.55. both are 39/11 tooth counts.
Heck, Richmond gear even switches between the two! Look up gears for a Dana, and 39/11 is a 3.54. Look up a Mopar 8 3/4, and the same 39/11 tooth count is listed as 3.55!
Go figure~
jh
The tooth counts for the D60 are 39/11, which equals 3.54545454545 etc.
Technically, you should round it up to 3.55, but some call it a 3.54
For rounding, you round a 5 up if the digit to the left is even, and down if it's odd. Since the 3.54 is even , the next 5 should be rounded up, giving you 3.55
There is no difference between a 3.54 or 3.55. both are 39/11 tooth counts.
Heck, Richmond gear even switches between the two! Look up gears for a Dana, and 39/11 is a 3.54. Look up a Mopar 8 3/4, and the same 39/11 tooth count is listed as 3.55!
Go figure~
jh
07-31-2007, 09:46 PM
#29
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Funny thing....my build sheet and the glove box sticker from Dodge says 3.55. The tags on the front and rear axles reads 3.54. I'm gonna figure they are 3.545's just to be fair.
07-31-2007, 10:10 PM
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Mine is about 1800 @ 70. Seems quite a bit of varying but I guess who knows if the guages are all correct. I do know that 2000 rpm is closeing in on 80 mph though.