Twin-Cooled to Centre-Cooled?
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Joined: May 2014
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From: Fort Frances
Twin-Cooled to Centre-Cooled?
I’ve been looking at some schematics and trying to find if there is much difference between the Twin-cooled heads and new Centre-Cooled heads(aka WetHeads/Gen2) on the +24 models. Maybe someone else would be able to chime in but I’m curious on if it would be possible to convert a Gen1 M8 Twin Cooled(17-23 Ultras/Limiteds) to the Gen2 Centre-Cooled system? This would give riders an option to reduce weight, and get rid of the lowers in hot climates, all while still having the benefit of a cooling system. It looks possible looking at parts schematics but some questions remain, are the heads the same or atleast similar for coolant circulation? Can the fan be wired without reprogramming of the ECM? And lastly is the frame the same for similar mounting?
I haven’t seen a Gen2 bike in person side by side to try and compare, and the closest dealer is 300mi away. But if all these questions can be answered yes with little difficulty, the cost in parts really isn’t that bad and could be a beneficial mod for all twin-cooled models that hate having permanent lowers.
I haven’t seen a Gen2 bike in person side by side to try and compare, and the closest dealer is 300mi away. But if all these questions can be answered yes with little difficulty, the cost in parts really isn’t that bad and could be a beneficial mod for all twin-cooled models that hate having permanent lowers.
Stellar HDF Member
Joined: Dec 2008
Posts: 2,001
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From: Madisonville, La
First the coolant flow is reversed going to the rear head first. Is the conversion possible yes, complicated yes, expensive probably.
In theory the ecm signal to the twin cooled fans and pump could power the center cooled parts. There could be ohm and load difference that throw codes or cause the ECM to disable the system.
Start by going to the HD web site parts, oem parts, model and year to see how many part numbers are different and their price.
Let us know how this works out.
In theory the ecm signal to the twin cooled fans and pump could power the center cooled parts. There could be ohm and load difference that throw codes or cause the ECM to disable the system.
Start by going to the HD web site parts, oem parts, model and year to see how many part numbers are different and their price.
Let us know how this works out.
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Joined: May 2014
Posts: 88
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From: Fort Frances
First the coolant flow is reversed going to the rear head first. Is the conversion possible yes, complicated yes, expensive probably.
In theory the ecm signal to the twin cooled fans and pump could power the center cooled parts. There could be ohm and load difference that throw codes or cause the ECM to disable the system.
Start by going to the HD web site parts, oem parts, model and year to see how many part numbers are different and their price.
Let us know how this works out.
In theory the ecm signal to the twin cooled fans and pump could power the center cooled parts. There could be ohm and load difference that throw codes or cause the ECM to disable the system.
Start by going to the HD web site parts, oem parts, model and year to see how many part numbers are different and their price.
Let us know how this works out.
HDF Community Team
Joined: Mar 2017
Posts: 7,935
Likes: 4,510
From: Texas
Parts that you’d need off the top of my head:
You’d probably be out more than you would with a trade in for the new bike. Newer bikes are less expensive than the older style.
- heads
- valves for new heads
- ignition coil
- plug wires
- horn
- coolant lines
- Coolant reservoir
- coolant pump
- radiator
- radiator brackets
- voltage regulator
- radiator cover/chin spoiler
- transmission top cover
- wire harnesses for new voltage regulator, coolant pump, etc.
- Engine guard
- floorboard supports
You’d probably be out more than you would with a trade in for the new bike. Newer bikes are less expensive than the older style.
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Joined: May 2014
Posts: 88
Likes: 4
From: Fort Frances
Parts that you’d need off the top of my head:
You’d probably be out more than you would with a trade in for the new bike. Newer bikes are less expensive than the older style.
- heads
- valves for new heads
- ignition coil
- plug wires
- horn
- coolant lines
- Coolant reservoir
- coolant pump
- radiator
- radiator brackets
- voltage regulator
- radiator cover/chin spoiler
- transmission top cover
- wire harnesses for new voltage regulator, coolant pump, etc.
- Engine guard
- floorboard supports
You’d probably be out more than you would with a trade in for the new bike. Newer bikes are less expensive than the older style.
Road Warrior
Joined: Jan 2022
Posts: 1,974
Likes: 5,478
From: Woodlands, MB, Canada
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Joined: May 2014
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From: Fort Frances
WPG and Gaslight are my closest dealers, I inquired about a trade on a 23 ST couple months back with my ‘19 FLTRU 25,000km. Both of them ball parked me around $20k but would have to see in person for a legit number. WPG even said they weren’t super interested in general since I was interested in an older model. That’s even after doing “stage 2” with all appropriate supporting parts and a dynotune on my bike. So I’ve just been using that number as a staple since they’re typically only going for $25-27k on the used market. It may have changed since then, but I haven’t rode into a city lately to find out. I really like my Ultra and all the comfort options it comes with, when I bought I didn’t realize how hot permanent lowers were going to be though.
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Intermediate
Joined: Jul 2019
Posts: 37
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From: Manitoba
anyone done a conversion
I came across this thread as I was researching modifying my 2018 Ultra to center cooled, like the new street glide. Since the frame on the 2024 street glide and the 2024 Ultra limited is the same part number, and the cooling system on the 2024 Ultra has the same part numbers as the 2018 Ultra, my assumption is that there is the possibility of converting the bike to center cooled. The advantages I am looking at is:
1) more options for lowers. Without having twin cooled in the lowers, I could get color matched ones from Advanblack or Hogwerks. There are also many other options.
2) Lower speakers. While you can get them for twin cooled bikes, the options are far greater for non twin cooled lowers.
3) Removing the lowers.
Has anyone else done the conversion? If so, was there any issues with the ECM? It was mentioned that the flow direction is different between the two. Any issue there?
Love to hear if anyone did it, and how it turned out.
1) more options for lowers. Without having twin cooled in the lowers, I could get color matched ones from Advanblack or Hogwerks. There are also many other options.
2) Lower speakers. While you can get them for twin cooled bikes, the options are far greater for non twin cooled lowers.
3) Removing the lowers.
Has anyone else done the conversion? If so, was there any issues with the ECM? It was mentioned that the flow direction is different between the two. Any issue there?
Love to hear if anyone did it, and how it turned out.
Road Master
Joined: May 2022
Posts: 854
Likes: 707
From: Near Memphis
<snip>...Since the frame on the 2024 street glide and the 2024 Ultra limited is the same part number, and the cooling system on the 2024 Ultra has the same part numbers as the 2018 Ultra, my assumption is that there is the possibility of converting the bike to center...<snip>
Sticking only to the cooling systems, you need to compare your bike to a '24-'25 Street Glide (Ultra or not is irrelevant). If you do that, you will see there dozens of different parts you'd need to get to "upgrade" your bike to a center-cooled configuration.
It took me 15 minutes to build this image ('24 on the left and '18 on the right). The new radiator assembly has 25 parts that add up to roughly $1,700. Luckily though, the temperature sensor is the same thus saving you $32. I don't even want to think about the harnesses. How about the ECU? Will the new cooling system provide same coolant temperature range? It'll be looking for the 2nd fan (continuity, current) and will likely start throwing codes if they aren't correct. Then there are questions about the harnesses. More questions about cooling flow and capacity. On and on...
CAN IT BE DONE? Yes, absolutely given the money and ability to troubleshoot issues and find workarounds and it would make for a great engineering project.
IS IT WORTH DOING just for more lower fairing options?
Last edited by Pappy35; Mar 11, 2025 at 02:21 PM.
