Why does my headset rock?

[Tricky1977]

Hello all,
I recently fitted a new FSA Orbit MX Aheadset to my Marin rock springs (with triple stanchion Manitou X verts), and I still have a slight rock/wobble present in the forks - something I’ve had before.

The wobble is when you apply the brakes and rock it back and forth, it’s not tight/concentric at the base (lower race), pics below.

Question/points:
- I’ve really tried to compress the upper “clamp” to ensure the forks are pressed tight
- I’m not convinced I’ve put the headset together correctly, there was only one split washer, which seems to be how it’s held concentrically, this I’ve used on the upper race as per some video guides.
- the FSA assembly diagram is useless
- Do I need a different lower race? Second Pic below…
- help!




Triple Stanchions and the lower race situation:

 

[ishaw]

Not wanting to sound like I'm teaching you to suck eggs, but here we go

Is the crown race the one that came with the headset? Is it tight on the fork steerer and flush against the crown? The gap between the race and lower cup looks excessive, perhaps you have the cartridge bearing the wrong way up? Should have the angled inner edge against the crown race, probably the angles outer edge against the top of the lower cup.

Are the bearings the right way up in the headset?

Is the top cap pushing against the steerer tube? You need a small gap to allow the pre-load to tension the whole assembly. If the top cap is sitting on the steerer tube, you won't be able to achieve the tension and will have play. You need the stem (or spacer if you run one on top of stem) to sit a few mins above the steerer tube, often depends on top cap. Perhaps the new headset has a shorter stack height than the old, or you've reduced spacer height?

Lastly, is the play in the headset or perhaps the fork bushings or even brakes? If you are putting brakes on and rocking, it could be brakes, if you are using the lowers as a lever, could be fork bushings. If using stanchions and there's rocking, probably headset.

Hope this helps and you solve the problem.

 

[Tricky1977]

Thanks very informative!

I’ll try my best….

No the lower race was already on there I just assumed it was correct as the “eBay special” FSA didn’t come with one
So this could well be wrong

Yes the lower race is tight but maybe there is a gap…
I did think that the bearings could go in upside down, but it all fitted snugly and usually they don’t look right upside down….checking means disassembly and the triple stanchions make this very hard. But I know I need to!

The cups are correctly oriented as they are “handed” so to speak

I’ll check the top cap space vs steerer too, good tip. This is quite likely as the whole forks are a little taller and I’ve used as many spacers as I can - the forks are new to me.

It’s definitely the headset inner diameter which has play versus the forks OD or lower race….

 

[ishaw]

Sounds like the crown race could be the culprit if it's not the one designed for the headset. They come in many flavours as do the bearings so could be a mismatch between the race and bearings. The gap alone suggests that as it should be minimal as it should seat snuggly and act as a seal of sorts to prevent crud getting in as well as a nice fit the the angle of the bearings.

 

[Suprachrgd82]

It is confirmed that the fork bushings are not loose/worn giving the feel of a clunky headset?

Correct me if I misinterpreted your post - the lower cup that is pressed into the headtube fit loosely?

If so, it’s worth removing and rotating it 90 degrees. Clean up any burrs in the headtube while it is out, particularly the bottom edge.

I do have the same headset installed on a Marin and have found no issues. I’d like to help get yours sorted.

 

[Tricky1977]

Hi it doesn’t feel like the shocks but I can check.
The lower race is press fit and very tight.
It just seems like there is a part missing, I have no faith in the selection of bits that came with my headset as there was no box/bag or instructions

 

[jimo746]

That fork crown race doesn't look right to me.
The eBay special FSA headset should have come with all the parts, including the crown race.
With older style loose ball bearing headsets you can sometimes get away with using a different crown race, but with these sealed bearings the diameter and angle of the race/bearing carrier has to be correct or you'll have problems.
I know it's a bit of work, but I'd take it all apart & confirm you've got all the correct parts in the right order.
If you're missing the crown race then get onto the eBay seller about it.

 

[bikeworkshop]

It's unusual to be able to set a headset up correctly with a different crown race.
If the headset came without the crown race, then you didn't get the headset, and it's definitely not New.
- so get your money back and get a complete one - or see if you can buy the right race and bill the seller.

Other classic problems are:
Any mismatched part.
Trapped rubber seal
Bearing upside down
Spacer to fit over expanding wedge missing
Not fitted parallel
(The number of people who fit their cups with a piece of wood and a mallet and then blame the manufacturer for poor adjustment and fast wear!!!)
Worn out bearings.

 

[fguki]

Wait ... so, you simply used any other random crown race that was on there with another headset you bought off ebay?

uh huh! ...

 

[benjabbi]

I'd say you definitely need the right crown race
https://shop.windwave.co.uk/spare-p...-race-h6033-for-orbit-x-alloy-118-inch__10345It's totally different to to the one you have, the chamfer won't be locating properly into the bearing hence the play.