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Difference between wide and narrow primary covers?
Recently purchased a 2018 softail slim which I believe has the wide primary on it. I am just learning now that a narrow primary is available from the 2019 and up softail .Can someone tell me what the difference is?, is the whole primary narrow or is it just narrow at the portion of the derby cover and if so, by how much?
Its just the area of the derby as far as I can tell. Also the derby covers are different between the two types so thats something to be aware of when looking for custom covers.
I can't tell you all the differences, but I can say that the "narrow profile" version has a 7.75" dia derby cover, while the previous version has a 7.25" dia derby cover.
2018 Softail models were a crossover year. They came equipped with the new Milwaukee 8 motor, but mostly retained the previous (Twin Cam style, 7.25″ dia) outer primary and derby cover. If you have a 2018 Softail, verify that your derby cover is 7.25″ in diameter, and select “1999-2017 Twin Cam Big Twin (five hole – 7.25″ dia”) when ordering. The exception is the 2018 FLSB Sport Glide. That one takes the newer, 6.4″ dia derby cover. If in doubt, measure!
Reading between the lines on your question, I don't know if you could take a narrow profile outer primary and swap it out on your bike. I'd be interested to learn if that is possible.
If you think about it, there is no real scope to make it narrower elsewhere other than the clutch because the internals, primary, compensator & clutch are all the same!
We have two 18 Model year M8 Softails and my wife did not like the position of the clutch bulge compared to her twin cam deluxe it replaced as her leg would pretty much touch it when stopped with feet down, so fitted the narrow primary which stopped this problem.
As said it's a direct replacement you do need to get a narrow replacement Derby inspection cover, fixing fasteners & gasket as these are all different. The fixing screws for the outer primary cover and gasket are identical!
You also need to swop over the damper weight ( The round cylinder in the middle of the outer primary cover) unless you get another, which is probably pretty pointless as again this is the same part!
It may be different for Canadian bikes, but my 18 primary cover measures the same as my twin cam, and 2 different people owning a 19 slim and a 2020 slim we all have the same size primary cover, 7.25 derby cover and 4 depth overall on clutch side without derby.
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Difference between wide and narrow primary covers?
