Hi all,
I've been lurking here for a while and finally bought an FLA104 high roof cabover with a Detroit 11.1, EFI 9 speed and, according to the spec tag, 3.36 rears. Previous owner said it's governed at 65mph. Tires are 295/75R22.5. It will be a hobby truck running a gooseneck equipment trailer, or pulling an enclosed car trailer.
On the trip home I ran an indicated 63-65mph at 1800 rpm, but was getting passed by everything on the road. Wife was following behind and said my actual speed was 58-60.
When I plug the current specs into a calculator, 3.36 gears and 22.5 rubber should run 65 at 1800 RPM. Maybe it's been swapped to 3.55's or lower?
Is the governor based on RPM or MPH? If I change to 24.5 tires will I be able to increase speed without reprogramming the ECM? (it's a DDEC II)
New to me Freightliner cabover...DD 60 tire size and governor questions
Discussion in 'Trucks [ Eighteen Wheelers ]' started by tinhunter, Dec 3, 2021.
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It is set both ways in a way. Max RPM and road speed are programable.
Rideandrepair and Oxbow Thank this. -
You can switch the tires from lo pro to tall R-11 22.5’s and get more top speed at the same RPMs. Maybe that’s what the Truck originally had. You can get even more top speed by going to 11/R24.5s, but would need new rims. Lo pro 24.5’s and Tall 22.5s are almost identical height. Play around with Spicers or Wellers calculators, to get a good idea. The speedometer can be calibrated by flipping the dip switches on the backside. Different settings for different drive lines combos. The settings can be found online. You should have a Ametek brand speedometer.
BoxCarKidd, tinhunter and Crude Truckin' Thank this. -
I checked the calculator. Looks like each tire size gets you about 2-3 mph more. The trans must be a 9 spd direct. Might be better to convert it to a 13spd. if it can be converted. If so, I think you’ll run about 65 mph at 1400 RPMs. With the same tires. As long as you’re hauling light, that would be ideal IMO. You could swap to a 9 OD. But a 13 would be nice, giving you more top gear choices. Those 11.1 get great fuel economy. Better than the 12.7s. Never saw one with a 13spd. Looks like 1800 RPMs would put you over 80 mph!! Lol. Looks like the directs serial # ends in A, and .73 final ratio 9 spd. OD ends with a B. I had a 9 OD with 390s. I loved it. I honestly don’t know much about it all. Just interesting to me. Others on here can help with numbers and ideas more than myself.
tinhunter Thanks this. -
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but the trans in the truck is definitely
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I'll have to look for a trans tag next time I have the cab up. I do like the idea of the Fuller bolt on 13 speed kits if that's possible.Rideandrepair Thanks this. -
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@wore out would probably know.
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Is it an RTO or RT?
the RTO 9 speeds were horseshoe pattern the RT were HRideandrepair Thanks this. -
Rideandrepair Thanks this.
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Rideandrepair Thanks this.
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