Hiya... has anyone got any experience with fitting a CBR400 tri-arm (aluminum swing arm) to a CBR600F? And if so, did it make any noticeable difference to the handling?I've been told the tri-arms are lighter and stiffer than the standard steel swing arm, and were exactly same basic dimensions foraxle, pivots etc. I'd be really keen for any feedback on this to avoid reinventing the wheel if it doesn't work out! Thanks!

 

i don't think that the triarm (singlesided) is any stiffer than a conventional swingarm. if you look at most superbikes, you will see that they are conventional swingarms with box section bracing as opposed to singlesided with a massive casting, massive box section, and top bracing. that one side has to be able to handle all that power without twisting on itself. if i wanted stiffer, i could easily weld a brace to the oem swingarm and gain more strength and it wouldn't be much heavier, maybe another 2 pounds.

i must admit that as far as looks go, nothing can beat a singlesider. i've seen pics of this swap/conversion and it looks really nice.

if you are looking to put an aluminum swinger on the bike i would suggest looking into a gullarm off a cbr400. this is a better setup imo. you have strength of a conventional swingarm and then some including the lighter weight. although i cannot see it being that much lighter.

does any of this make for better handling. i would have to say probably not much if any. i have replaced my suspension at both ends with more updated parts or aftermarket, and it is a far better and easier upgrade that gives very good results. a weakness of this model is its lack or limited range of suspension adjustability.

 

Thanks Michigan_313 -I know the VFR400swing arm of about that time was single sided, but the aluminum swing arm I have is double sided. I can't find anyparts drawings or fiche on the net for the CBR400 tri-arm (spent about an hour googling - none of the usual places have it), so I can't be certain that its a 400 one, only going by what the seller said. Depending on any other replies, I'll compare physical tri-arm with orginial steel swing arm (dimensions, weight, stiffness) & see how it goes.

 

cbr 400 came in two types - nc23 (tri-arm) and nc29 (gullarm)
tri-arm is 2 sided braced and gull-arm is 2 sided but non-drive side bent. (this point is where i had a brainfart)

the swingarm pivot inside width of the cbr 600 is 228mm. the oem swingarm pivot width is 222mm. these measurements are pretty accurate.

have you tried searching ebay for pics of a cbr400 swingarm. i will have one in a few weeks. i'm waiting for it to be shipped from UK. it is slightly wider using a 4.5"x18" rim. that will be replace by a 4.5"x17". the suspension arm and rod assembly look exactly alike to the 600, most likely a parts recycle.

i'm pretty sure this will fit without any chain line issues. i would have liked to have gotten ahold of a gullarm, but those seem very difficult to find from the breakers. that would make for nice custom exhaust routing.

i also know that a nc35 (rvf400) will slot right into the cbr600 frame. that's the easy part. hard part is either relocating the suspension point on the frame, redoing the suspension point on the arm, or both. and this runs a 17" rim. i think the nc30 (vfr400) will work as well, but with the same issues as the nc35.

this is as close to anything i have to a drawing.
http://www.vsource.org/VFR-RVF_files...JP1991-10a.jpg

i just found this: http://pdftown.com/PDF-Honda-CBR400-Repair-Manual.html

maybe it will give you somemore insight into what you are doing.

 

Thanks! I've weighed the swing arms - the tri-arm is nearly 1 kg heavier (!) than the standard steel CBR swingarm, andit is about 30-35 mm shorter (centre-line ofpivot to rear axle at mid adjustment). So I don't think I'll fit itin case it upsets the handling due to changed geometry & increased weight. I'll stick with the standard CBR swingarm. Am at the moment fitting emulators to the front end - think that's about as far as I'll go with suspension mods. Let me know if you have any difficulty getting the UK tri-arm - the only reason I'm hanging on to mine is for the bearings in case they're interchangeable with the CBR600 ones. Haven't found a parts manual for the CBR400 yet.

 

what happened, link to pdf didn't work? that is a full manual for cbr400.

i'm still waiting for arm to ship. i don't know what area of the UK you live in but maybe i might take you up on it. thanks for the offer.

weight shouldn't be an issue since it is low in relation to the frame. and being shorter may make for being slightly wheelie prone but i can't see that happening unless running high bars. other than that, a short wheelbase should make for quick turning.

 

Yes, the pdf link worked thanks! What I meant was that I was looking for the part numbers for the CBR400 swing arm bearings to compare with the CBR600 part numbers (which I have) - the service manual doesn't give them. Parts here are really expensive. I can't find any 400 tri-arm part number listings on the 'net.