Topic: CB550 forks on a CB400F

[dawdish]

I would like to have the bigger brake, wheel, and width of the 550 fork on my 400f. Is there any reason that wouldnt work ?

[grcamna2]

I believe that it's a direct swap with the steering head bearings being the same.

[dawdish]

I believe that it's a direct swap with the steering head bearings being the same.

Thank you, I thought as much.

[grcamna2]

I believe that it's a direct swap with the steering head bearings being the same.

Thank you, I thought as much.

To keep the 400F's Nice handling..it'd be good to lace up an 18" front rim to the CB550 front Hub.

[dawdish]

I believe that it's a direct swap with the steering head bearings being the same.

Thank you, I thought as much.

To keep the 400F's Nice handling..it'd be good to lace up an 18" front rim to the CB550 front Hub.

Forgive my ignorance, why would keeping the 18" make it handle better? I have heard the opposite. One reason I'm doing this is to get bigger rubber up front.

[bwaller]

The 400 has more offset, if you switch just keep the original triple clamps. Not sure if the 550 forks aren't longer, but you can run those through the clamps some. I agree don't put a 19" front wheel on your 400. Besides getting good 19" rubber is even harder than 18".

[jessezm]

I thought 550 forks were 35mm?  They won't fit into the 400f triple (33mm), will they?

[kyre]

Yeah 550 = 35mm and 400 = 33mm so the cb400 triples wont fit 550 tubes. I've been running a 550 front end (with dual disks) on my 400f for the last 7/8 years (with a 18in rim laced to the 550 hub). All I have to say is what an improvement over the stock set-up! I used to be sketched to drive my 400 on the highway with the original set-up; although the springs weren't that good and it had the original headset bearings at the time. When I put the 550 front end on I put roller bearing in the headset and progressive springs upfront. The fork tubes are also longer so I slid the triples down about 3/4in. I know the 400 has more offset in it's stock form but I love the way my bike rides and handles with the 550 front end. I'd never go back.

[bwaller]

Oh #$%* sorry boys, brainfart.

[dawdish]

Yeah 550 = 35mm and 400 = 33mm so the cb400 triples wont fit 550 tubes. I've been running a 550 front end (with dual disks) on my 400f for the last 7/8 years (with a 18in rim laced to the 550 hub). All I have to say is what an improvement over the stock set-up! I used to be sketched to drive my 400 on the highway with the original set-up; although the springs weren't that good and it had the original headset bearings at the time. When I put the 550 front end on I put roller bearing in the headset and progressive springs upfront. The fork tubes are also longer so I slid the triples down about 3/4in. I know the 400 has more offset in it's stock form but I love the way my bike rides and handles with the 550 front end. I'd never go back.

Thanks guys, that all helps. I didn't think there could be that much of a problem.If the the offset of the 550 was not desirable, the 550 wouldn't be so popular, and I dont recall any complaining about the handling of them.

[kajtek]

Yeah 550 = 35mm and 400 = 33mm so the cb400 triples wont fit 550 tubes. I've been running a 550 front end (with dual disks) on my 400f for the last 7/8 years (with a 18in rim laced to the 550 hub). All I have to say is what an improvement over the stock set-up! I used to be sketched to drive my 400 on the highway with the original set-up; although the springs weren't that good and it had the original headset bearings at the time. When I put the 550 front end on I put roller bearing in the headset and progressive springs upfront. The fork tubes are also longer so I slid the triples down about 3/4in. I know the 400 has more offset in it's stock form but I love the way my bike rides and handles with the 550 front end. I'd never go back.

Did you have any issues with the forks hitting the tank?

[kyre]

Forks don't hit the tank but I do have clip-ons and the design of them makes the clamps hit the tank so I modified the stops. If I get a different set of clip-ons with the clamps in a different position there wouldn't be a need to modify the fork stops.

[ummagawd]

So i've considering doing the same thing, but still contemplating if it'd be more cost effective to change oil weight, lower tree clamp, and add emulators.

The part of this analysis I'm missing is the wheel part. Would I need a 550 wheel? Is there anyway to use the 400f wheel?

Thanks

[faux fiddy]

Oh #$%* sorry boys, brainfart.

It didn't stink so ....no harm no fowl [odor].

There must be build threads and other things to find about this in the search.  It's been done repeatedly.

FAQ has good info on sizing triple trees, head tube stack highth, bearing sizes  and fork diameters.

http://forums.sohc4.net/index.php?topic=370.msg512053#msg512053

[camelman]

Another route is to install a lower billet triple tree.  that's the main source of flex on our bikes since they were designed more for low cost than high performance.  Just swapping in a more robust lower triple (and stem) will make a huge difference and allow you to keep the rest of the bike stock.  TTR400 sells a sweet setup for not too much money.  If you compare the difference in cost between retrofitting a 550 front end to just installing a 400f lower tree, then I bet you'll see some benefits in going with the billet lower tree.  FYI, I bought two of those suckers for my current builds.

If you go the 550 route, then you'll need to lace up an 18" rim to the 550 hub.  I think the stock 350/400 rim is 36 spoke and the stock 550 hub is 40, so you'll need an aftermarket rim (pricey) to build the wheel. 

Camelman

[ummagawd]

Camelman... thanks... i've read about that too. In your opinion/experience.... would a billet lower, different oil weight, and maybe pre-loaders be enough for a stable ride at highway speeds?


And what are everyone's thoughts on spacers? I know I'd be missing out on the dual disc if i kept my 400f wheel, but just curioius if that would be a viable way to go also.

[camelman]

I have ridden similar billet lowers to TTR's, but never his. However, I am very comfortable with his products and expect equally impressive results. Regarding your highway issues, you should be comfortable at speed. If not, then try 10 weight fork oil, tapered steering bearings, a new tire if yours is old, and check your rim for roundness. Worn swing arm bushings and bad shocks can cause issues too as can improper tire sizes or pressure.

My 350f is stable to 80+ with a slightly unround front rim, stock triple, good swing arm, new shocks and new fork oil. A billet triple tree will make a difference. The last one I rode on a 400f totally transformed the bike. YRMV.

Camelman

[ummagawd]

thanks for the list Camelman... it looks like the costs to go 550 front end (with an 18" wheel) is looking to be about the same cost as modifying the cb400 suspension.

oh decisions 

[camelman]

Ha!  Decisions are tough for sure!!  I should have my 350f back together with TTR's triple tree setup installed in the next month. I'll let you know how it performs then. I'm using 400f forks, so it should be virtually identical to your 400f for handling. If you happen to get to SF, then you can take it for a ride.

[Bodi]

You gain a lot of rigidity going from 32 to 35mm tubes. It seems like a small change, but rigidity is proportional to the fourth power of the diameter. That 3mm increase gives you about a 60% increase in fork rigidity.
I can't find the document right now, but I have instructions on swapping to (I think) 550 legs. To get the offset correct you use a 450 triple tree, removing the tube and welding in the 400F tube. I don't recall if they used an 18" wheel - modified 550 or original 400 - or if custom spacers were required. Gauge and headlight mounting will have to be figured out.

[camelman]

One other thing that makes a MASSIVE difference in handling and performance of your bike is to get your weight off the handlebars in the turns. If you are riding hard, then try to keep a light hold on the bars except for when you are steering the bike into or out of a turn. If you are holding on to the bars tightly, then you are going to throw the suspension off, or at least end up fighting it unknowingly.  It made a huge difference in how my 350f handled.

35 mm tubes will definitely help, but those 33mm tubes should perform well too.

Camelman

[kyre]

I pretty much funded my 550 front end by parting out my 400 front end. I did go dual disk so I had to buy an extra caliper and arm, pads, disk, master from a 79 GL1000 and new braided lines. I bought a 40 hole 18" rim on eBay for $40 which has lasted me 8 years now although if I had the money I would have bought an aluminum shouldered rim. Stainless spokes from Buchanan and new progressive fork springs also.

I'm using a cb550 triple with an aluminum upper triple clamp from a 79 CBX since I'm running clip-ons. Everything bolted right up, no pressing out the triple stem, fits right in the 400, although you'll need new roller bearings for the headset..

I love this setup, so much more rigid than stock, although I have no experience with an upgraded stock front end. I bet it's still super nice and handles way better than leaving everything stock. You'll be happy whichever way you choose..

[ummagawd]

well... you guys definitely are NOT making this decision easier  JK

I appreciate the info

[74CB400FFourSS]

I pretty much funded my 550 front end by parting out my 400 front end. I did go dual disk so I had to buy an extra caliper and arm, pads, disk, master from a 79 GL1000 and new braided lines. I bought a 40 hole 18" rim on eBay for $40 which has lasted me 8 years now although if I had the money I would have bought an aluminum shouldered rim. Stainless spokes from Buchanan and new progressive fork springs also.

I'm using a cb550 triple with an aluminum upper triple clamp from a 79 CBX since I'm running clip-ons. Everything bolted right up, no pressing out the triple stem, fits right in the 400, although you'll need new roller bearings for the headset..

I love this setup, so much more rigid than stock, although I have no experience with an upgraded stock front end. I bet it's still super nice and handles way better than leaving everything stock. You'll be happy whichever way you choose..

I'm doing a similar front end swap on my 75 CB400F SS I was wondering what year 550 and what size 79 CBX you got the upper triple from?

[grcamna2]

One other thing that makes a MASSIVE difference in handling and performance of your bike is to get your weight off the handlebars in the turns. If you are riding hard, then try to keep a light hold on the bars except for when you are steering the bike into or out of a turn. If you are holding on to the bars tightly, then you are going to throw the suspension off, or at least end up fighting it unknowingly.  It made a huge difference in how my 350f handled.

35 mm tubes will definitely help, but those 33mm tubes should perform well too.

Camelman

I agree w/ you Camelman on that weight transfer riding style mod. When I get used to a bike(a low,flat handlebar helps...) I do light touch countersteering w/ a lot of left & right weight on my footpegs & knee into the tank. When I have stock(higher)bars,I use them more w/ countersteering along w/ my knees into the tank.
It works for me.