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1979 CB750F front and rear calipers

jrg_race

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Does anyone know if any other model calipers will work with existing mounting holes on front forks? or existing caliper brackets? like perhaps the 900C from the 1982?
 
Also, my 1979 CB750 F appears to have a steering stem similar to the '78, meaning after the bearing pre-load nut, there is not additional lock washer before installing the top fork bridge.

https://www.hondapartshouse.com/oemparts/a/hon/506f7afdf8700229747b847c/steering-stem-horn

My bike appears to have no #12, 13 from diagram in link above

https://www.dotheton.com/index.php?threads/cb750-steering-stem-locking-nut.58355/

More along the lines of the '78 pictured in link above.

Does anyone have experience with this?
 
It's trouble sorting calipers. '79-'80 F work as do '79-'80 CBX, and thinking '80-'82 900C do too. Most '81 and later went to twin piston.

You need the extra lock parts on the '79 model, those went to steering head bearings that are tapered roller which require a slight bit of preload, you do not just take up all slack like the '78 model which uses balls there. The '79 and later actually uses 3 parts there, the threaded one that actually covers the bearing, the lock on top to doublelock and another lock goes on top of the upper bridge.
 
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It appears the ‘79 750F steering stem is unique compared to the models following it because it does not require additional locking nut after the preload nut and before the top fork bridge. At least my bike didn’t have one, I can’t find any pictures online with any, nor is an additional lock nut reflected on Honda Part House.
 
https://www.partzilla.com/catalog/honda/motorcycle/1979/cb750f-a-750-super-sport/steering-stem-horn

Look there and not so. You CANNOT leave the steering head preload unlocked like that, it's dangerous. My '80 has the parts and '79-'80 are the same bike other than paint and wheel type. Add to that if you tighten the very top nut that pushes down on the upper triple clamp with those parts being under it to support it then you will likely crack the triple as you are pulling it out of plane at the back in relation to upper fork tubes if already tight there. You're asking for it depending on what order you tighten things up in.
 
You are confusing things to say the least. The pic shown at Honda Part House clearly shows both parts. Just because they are not shown in the parts number list to the right means nothing. Occasionally the parts fiche gets updated and anything listed as 'unavailable' then disappears too to trim the list down. 12 and 13 being gone means they have been unavailable for a long time. Look at carb parts, you likely will see lots of missing numbers there that the bike not having would cease to run. I've seen some price lists on older bikes with a hundred parts shown on the pic but only 5 or 6 in the price list to the right, that is all that is left.

12 and 9 are locking nuts that jam against each other to lock the bearing race preload. 13 IS a lockwasher but the bent tab type that bends a tab into one of the notches to lock it down more.

https://www.partzilla.com/catalog/h...-750-super-sport/handlebar-top-bridge-key-set

Part #18 in the above link is the third lock nut that will crack your triple if you don't have the other two missing parts in place to stop the back of triple from warping down too far to crack.

It's obvious somebody has had yours apart to not use all the parts going back together for whatever reason people do such whacky things. With those parts missing the part #9 can slowly back off from bearing impact and can cause you to crash, DON'T leave it like that!
 
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Yeah, they use the same diagram. But most importantly the part numbers are clearly different for the stem. Nor do they even list the #12, 13 parts for the ‘79. Therefore, the ‘80 is different. Also it would not be any more dangerous than the ‘78 and earlier models because they also did not use an additional lock nuts after preload adjustment nut.
 
The part number is the SAME, the only thing that changed was the latter part or the classification number, which likely means the vendor of the part. The number being 000 likely means the vendor was not known when the first fiche was composed, the 770 added later means they finally knew who it was. The #9 locknut part more importantly is the SAME for both years meaning the threads did not change. In short you have no reason to think the parts are different in a way to allow you to not use some of them. The parts listed for '80 means you also have no excuse for not using them, they will interchange.

The reason for earlier SOHC not using the second locknut is they don't need to, the back of the triple does it and look at how it is designed. The back hole is split with a bolt and DOHC does not do that. The SOHC triple pulls down against the the main locknut to lock it in place then you tighten the side bolt to lock that like a locknut. The DOHC part does not do that and why the separate locknut is needed.

I've told you why that locknut is needed and you have been warned. Yours and do with it as you will. It IS more dangerous than the '78, you clearly do not understand why.
 
People who list part numbers often let them disappear on the oldest models, it keeps parts in use more currently in line with more recent models. It sells more parts to list it in the later lists. I have updated NLA parts way more than once by looking in later year applications where I know the same parts are used, it can be the difference in finding them or not.

Get this one............I used to have an '80 Pinto wagon. Ford got so much flak over that car they at some point determined to get them all off the road as quickly as possible due to lawsuits popping up left and right. They simply voided the parts books as no longer available. I replaced parts with Mustang II parts for the next few years when Pinto parts ceased to be available; they either bulldozed them into a field or sold the ones that worked on the Mustangs as Mustang parts, and how I ordered so many of them. Almost 100% of the front ends and rears and entire powertrain were the same in both cars as well as most emission equipment. Different part numbers? I didn't care, the parts fit and worked perfectly.

I learned to do it based on a '68 Yamaha 305, a model that had very few made, but it was based on the 250 and much of the same applied. I bought I bet a hundred 250 parts for that 305 and not one problem. Same with Honda 500-4 and 550, much of it is the same parts. The later '79-80 650 DOHC uses a big chunk of DOHC 750 stuff too.
 
Yeah parts are interchangeable on lots of things. Maybe someone with a 1979 CB750F would be able to clarify if there is a two locking but system UNDER the top fork bridge.
 
My '83 Nighthawk has the locks too.

No matter as you may BE RIGHT.

http://www.cb750c.com/publicdocs/CB...erviceManualChapter13FrontWheelSuspension.pdf

Look at the '79 K model there which does NOT have the pieces, the K fork is the same fork as F in that year other than paint and maybe caliper hole location, one is likely blank. There is no mention of the extra pieces in the assembly work.

They would have had to make a change there and how to tell?

You will have to assemble parts and look at how much room you have between the upper triple bridge and the top of the one lock nut you want to use. They should hit (so the triple locks the nut in place) when the back main stem nut is tightened up. If you use the upper lock pieces in question you need another 1/4"-3/8" or so for room to install them meaning the triple will not touch the lock nut at all and why I say tightening up on that will likely crack the bridge. If you have a lot of space there you need the parts. Look in that link, one pic shows the install from the side and it looks like the triple does hit the top of nut, it should be fairly easy to see. I also found a blowup of the triple area that did not show the pieces at all like they are not used.

Page 13-2 shows evidence of not using the parts, the part at top about hard steering being top nut too tight means they are relying on it to lock the lower locknet in place rather than the two missing pieces.

13-20 and 13-24 show the height the fork tubes clamp in the triple at, or dead flush to maybe 1/8" of fork tube sticking out of the triple. You need to know that in re-assembly to have the triple at correct angle for the extra space checking to determine if you need the extra parts or not.

13-25 to 13-28 detail the taking apart and putting back together and no mention of the extra parts at all. Your F uses virtually the same parts, I would not worry about the service manual being a K one.

I apologize for running you through the mill on this, it is apparent now they did it in two ways to me. A careful looksee at assembly should tell you whether you need the extra parts or not. If the triple hits top of locknut then you don't use them.

Sorry for all the fuss.
 
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I appreciate your thoroughness and willingness to help out. I want to be certain, because as you said, if two locking nuts are required, it would be silly and most likely very dangerous to not have them. It appears I do not have extra space for a second nut. I am half tempted to order a 1980 CB750F steering stem and measure the length.
 
If the top triple contacts the locknut you do NOT need further, it serves the same function when the back nut gets tightened. Bikes have used that method as well for many years.
 
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