Transmigration question.
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Posting Guru
Joined: Feb 2013
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From: Sunny Florida
Transmigration question.
When it comes to transmissions, I am am idiot. I currently have three running and driving Dents. All have the C6, one behind a 360, one behind a 302 (have to double check could be a C4), one behind a 300.
All three trucks seem to shift to second really early and third around 30 MPH. So by the time I hit 55-60, the engine is turning pretty high RPMs. Obviously an OD transmission or a manual with more gears makes sense to fix it, but is there a way to adjust the shift points on the three speeds?
All three trucks seem to shift to second really early and third around 30 MPH. So by the time I hit 55-60, the engine is turning pretty high RPMs. Obviously an OD transmission or a manual with more gears makes sense to fix it, but is there a way to adjust the shift points on the three speeds?
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Posting Guru
Joined: Feb 2013
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From: Sunny Florida
I understand that, but I am going all of 10 miles an hour when it shifts into second.
Lead Driver
Joined: Apr 2011
Posts: 6,399
Likes: 40
From: El Dorado, Arkansas
More gears only spreads the gear ratios out of the transmission.
A C-4, C-6 or any non-overdriven transmission is going to be 1:1 in high gear.
An overdrive transmission, standard or automatic, is typically 2/3rd overdriven. --usually ~.67:1 (but can vary).
Final drive equivalent for the vehicle will be whatever the rear end ratio is, multiplied by the high gear (or overdrive) ratio of the transmission.
A C-6 has a 1:1 ratio in 3rd. If you had 3.50 gears with a C-6, you would multiply 3rd gear by the rear end ratio.
1:1 x 3.50:1 = 3.50:1.
If you had an overdrive transmission that had a .67:1 overdrive ratio, you would multiply that by the rear end ratio to get the final drive equivalent.
.67:1 x 3.50:1 = 2.35:1.
In overdrive, the final drive equivalent would be as if the rear end had 2.35:1 gears. This would produce far less RPMs at highway speeds.
A C-4, C-6 or any non-overdriven transmission is going to be 1:1 in high gear.
An overdrive transmission, standard or automatic, is typically 2/3rd overdriven. --usually ~.67:1 (but can vary).
Final drive equivalent for the vehicle will be whatever the rear end ratio is, multiplied by the high gear (or overdrive) ratio of the transmission.
A C-6 has a 1:1 ratio in 3rd. If you had 3.50 gears with a C-6, you would multiply 3rd gear by the rear end ratio.
1:1 x 3.50:1 = 3.50:1.
If you had an overdrive transmission that had a .67:1 overdrive ratio, you would multiply that by the rear end ratio to get the final drive equivalent.
.67:1 x 3.50:1 = 2.35:1.
In overdrive, the final drive equivalent would be as if the rear end had 2.35:1 gears. This would produce far less RPMs at highway speeds.
Lead Driver
Joined: Apr 2011
Posts: 6,399
Likes: 40
From: El Dorado, Arkansas
If you change rear end gears but keep the current transmission, you'll have to decide what the truck will primarily be used most for, before choosing a rear end ratio.
If you want highway mileage, you'll have to go higher (lower numerically) with the rear end ratio. This will give decent mileage and lower cruising RPMs but, towing/pulling and acceleration ability is going to suffer.
If the truck will primarily be used to pull/haul heavy loads, you'll have to go lower (higher numerically) with the rear end ratio. This will be good for pulling and for acceleration but, it'll be bad for fuel mileage and cruising RPMs on the highway will be high.
If you had an overdrive though, you could have lower rear end gears (higher numerically) that will be good for pulling or acceleration and you would be able to get decent highway mileage with much lower cruising RPMs. --an overdrive would give you the best of BOTH worlds.
If you want highway mileage, you'll have to go higher (lower numerically) with the rear end ratio. This will give decent mileage and lower cruising RPMs but, towing/pulling and acceleration ability is going to suffer.
If the truck will primarily be used to pull/haul heavy loads, you'll have to go lower (higher numerically) with the rear end ratio. This will be good for pulling and for acceleration but, it'll be bad for fuel mileage and cruising RPMs on the highway will be high.
If you had an overdrive though, you could have lower rear end gears (higher numerically) that will be good for pulling or acceleration and you would be able to get decent highway mileage with much lower cruising RPMs. --an overdrive would give you the best of BOTH worlds.
Thread Starter
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Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
If you change rear end gears but keep the current transmission, you'll have to decide what the truck will primarily be used most for, before choosing a rear end ratio.
If you want highway mileage, you'll have to go higher (lower numerically) with the rear end ratio. This will give decent mileage and lower cruising RPMs but, towing/pulling and acceleration ability is going to suffer.
If the truck will primarily be used to pull/haul heavy loads, you'll have to go lower (higher numerically) with the rear end ratio. This will be good for pulling and for acceleration but, it'll be bad for fuel mileage and cruising RPMs on the highway will be high.
If you had an overdrive though, you could have lower rear end gears (higher numerically) that will be good for pulling or acceleration and you would be able to get decent highway mileage with much lower cruising RPMs. --an overdrive would give you the best of BOTH worlds.
If you want highway mileage, you'll have to go higher (lower numerically) with the rear end ratio. This will give decent mileage and lower cruising RPMs but, towing/pulling and acceleration ability is going to suffer.
If the truck will primarily be used to pull/haul heavy loads, you'll have to go lower (higher numerically) with the rear end ratio. This will be good for pulling and for acceleration but, it'll be bad for fuel mileage and cruising RPMs on the highway will be high.
If you had an overdrive though, you could have lower rear end gears (higher numerically) that will be good for pulling or acceleration and you would be able to get decent highway mileage with much lower cruising RPMs. --an overdrive would give you the best of BOTH worlds.
I read on another thread about the 4R70W needing a stand alone shift module. Any input on this tranny and where I could find the module for sale?
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Frmr Ford Trans Engr
Joined: Aug 1999
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From: SE Florida
The vacuum modulator (where the vacuum line attaches to the transmission) has a screw that will adjust the shift speeds.
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Lead Driver
Joined: Apr 2011
Posts: 6,399
Likes: 40
From: El Dorado, Arkansas
I pulled my 4R70W from a 3.8L '98 Mustang. The 4R70W came out in 1993 but, the best models of this transmission were from 1998-2004.
I bought my shift controller from this company.
The US Shift Transmission Control System
Good information on this transmission, written by one of the Ford transmission engineers that designed it.
TCCoA Tech Articles
If you're thinking about running one of these transmissions, my best suggestion is to do a web search and read/study all the information on it you can find, to learn all you can and to be informed about it, before going out and buying one.
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Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
My 4R70W isn't installed in my truck, yet, due to the fact that I have to rebuild the transmission but, it's also because I have a 5.0L EFI engine from a '90 Mustang GT that has to be gone through before that, until they can both be put in my truck.
I pulled my 4R70W from a 3.8L '98 Mustang. The 4R70W came out in 1993 but, the best models of this transmission were from 1998-2004.
I bought my shift controller from this company.
The US Shift Transmission Control System
Good information on this transmission, written by one of the Ford transmission engineers that designed it.
TCCoA Tech Articles
If you're thinking about running one of these transmissions, my best suggestion is to do a web search and read/study all the information on it you can find, to learn all you can and to be informed about it, before going out and buying one.
I pulled my 4R70W from a 3.8L '98 Mustang. The 4R70W came out in 1993 but, the best models of this transmission were from 1998-2004.
I bought my shift controller from this company.
The US Shift Transmission Control System
Good information on this transmission, written by one of the Ford transmission engineers that designed it.
TCCoA Tech Articles
If you're thinking about running one of these transmissions, my best suggestion is to do a web search and read/study all the information on it you can find, to learn all you can and to be informed about it, before going out and buying one.
Thread Starter
|
Posting Guru
Joined: Feb 2013
Posts: 1,323
Likes: 3
From: Sunny Florida
Any how to articles?
Freshman User
Joined: Apr 2013
Posts: 48
Likes: 0
i had one rebuilt that shifted way early , drove it like that for a while till i broke the trans had the same guy rebuild it told him it wasnt right ban when i got it back it shifted right he said it was out of adjustment a it worked as it should till i sold it
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