Help! Upper Yoke Fixing Bush Won't Budge

Message

D-Rider · #1 Post by **D-Rider** » Mon Jun 08, 2009 9:40 pm

I was planning to swap my forks tomorrow to fit the Ohlins but I've hit a big problem.

I can't remove the upper yoke fixing bush .... part no 8 in the diagram:

It requires a 14mm hexagon (Allen Key). That isn't the problem - I picked one up ready for this - it's a 14mm oil plug key that I got from Halfords. It is designed to be used with a 3/8" socket drive.

So i tried to undo it using my 3/8" drive ratchet. It wouldn't move. I put an extension tube on the end and pulled all I dared - but stopped as I was a bit concerned that the ratchet mechanism would break.

I then found a 3/8" square that was part of an old car jack winder.That went into the 14mm hex key and (with an extension) I heaved again .... and things felt as though they were moving .... until I noticed that it was the steel jack part twisting .... on it's way to shearing (fortunately I stopped before then).

So ..... has anyone any ideas? There's no point in heating the yoke fixing bush - it has an external thread and screws into the steering stem - heating will only make it tighter. I can't heat the steering stem as I can't get at it.

I'm struggling here!

Samray · #2 Post by **Samray** » Mon Jun 08, 2009 9:50 pm

Round the garage and see if a pneumatic gun will shock it loose?

D-Rider · #3 Post by **D-Rider** » Mon Jun 08, 2009 9:54 pm

Cheers Sam - that's a good idea - one for first thing tomorrow.

fastasfcuk · #4 Post by **fastasfcuk** » Mon Jun 08, 2009 10:22 pm

only an idea andy i ca'nt see why it would be, but it's not left hand thread is it.failing that give your extension bar a good sharp tap to try and losen the threads.i prefer to use 1/2 inc drive i put a 21mm socket over the sump removel tool which will give you more bite.
hope that helps.

D-Rider · #5 Post by **D-Rider** » Mon Jun 08, 2009 10:48 pm

No it's not a left hand thread - that was one of the first things I checked when it wouldn't budge.
I agree it would be better to use a 1/2" drive - I was trying to work out a way I could do that.
I can't figure out quite what you're saying about using the 22mm socket - can you explain for the hard-of-thinking please.

tommy · #6 Post by **tommy** » Mon Jun 08, 2009 11:35 pm

Just had to do mine when i changed my yoke for my renthals. Was just as stuck. Used 1/2" drive 14mm hex bit, and a 2 foot breaker bar. Its a very fine thread. Just use plenty of WD40 and slow and steady pressure on breaker bar. I wouldn't use 3/8" drive - It will shear in seconds

fastasfcuk · #7 Post by **fastasfcuk** » Mon Jun 08, 2009 11:44 pm

sorry andy i posted before i looked at the tool you were useing, my plug removel tools have a different size on each end with 21mm hex in the middle so i can get a 1/2 inc drive socket over them. you can get a 1/2 to 3/8 reducer. failing that i will gladly post mine to you.

D-Rider · #8 Post by **D-Rider** » Tue Jun 09, 2009 12:17 am

Cheers everyone .... just had a reply from kzmille on AF1 .... pointed out it's torqued to 58lb ft .... I checked the manual .... yep 80Nm .... no wonder it's beyond my 3/8" stuff.
I'll pop to the tool suppliers tomorrow and see if I can get something I can get my 1/2" drive on (If not, I'll get back to you Ian)

Many thanks

Syltiz · #9 Post by **Syltiz** » Tue Jun 09, 2009 8:35 am

I used a massive breaker bar on mine... 3 or 4 foot i guess (not good with non-metric measures), anyway - its long (the breaker bar... obviously)

#10 Post by **mangocrazy** » Tue Jun 09, 2009 9:22 am

Breaker bars are ace. For something like the fork yoke top nut I'd be tempted to get a 3/4" square drive and use a 3/4" to 1/2" reducer on the socket if need be. The weak point will always be the pivot on the breaker bar.

I always carry a breaker bar in the car or van with a 19mm socket on just in case I get a puncture. I've sweated and cursed with enough inadequate wheel nut removing tools to never want to do it again. If you go to a trade motor factors (i.e. not somewhere like Halfrauds) you can pick one up for not very much.

D-Rider · #11 Post by **D-Rider** » Tue Jun 09, 2009 12:18 pm

OK right tool for the job and all that ..... a quick visit to the tool shop furnished me with a 14mm hex bit with 1/2" drive .... heave-ho and we were sorted.

My next job was to see what size socket I need to cannibalise to make a peg spanner to undo the nuts at the top of the steering stem (5 & 6 in the picture at the top of the thread).
First surprise is the locknut was completely loose - held only in place by the tab washer. I know it's only meant to be finger tight plus 1/4 turn but this was more like finger tight minus 1/4 turn.

Anyway measured it up then decided to see how things lined up with the top yoke for the Ohlins ...... that's where the next problem comes .....

Yep ... the hole for the steering stem is MUCH smaller on the yoke I have for the Ohlins.

For the life of me I can't work out why!
The standard Mille bottom yoke and stem is the same as the Falco and the standard Mille and MilleR both use the same upper yoke fixing bush (the thing I was struggling with yesterday) - so the hole in the top yoke should be the same.

Now I'd better explain the story with the yokes. I bought them with the forks and they do fit the fork legs properly - although the top yoke was never fitted over the stem (looking at it, it won't fit). The chap who sold them to me remembered that the bottom yoke had a Yamaha stem in it (apparently his mate was going to fit them to a Yam at some point). Anyway, I got the Yamaha stem pressed out and a Falco stem pressed in.

Hadn't ever put these upper and lower yokes together and never entered my mind there could be a problem!

So ..... what Aprilia top yoke fits Ohlins forks but has a small hole for the steering stem?
BTW ignore the smaller holes either side - his mate with the Yam was going to fit higher bars. Also ignore the fact it's bare ally - it was black when I got it.

Looks as though I'm going to have to get it bored out.

..... Why can't anything ever be simple?!

Samray · #12 Post by **Samray** » Tue Jun 09, 2009 12:38 pm

It's enough to give you hiccups !!

D-Rider · #13 Post by **D-Rider** » Tue Jun 09, 2009 12:46 pm

Samray wrote:It's enough to give you hiccups !!

Doh! ... hit "quote" instead of "edit" .... all sorted now ..... unlike my yokes .........

#14 Post by **mangocrazy** » Tue Jun 09, 2009 1:12 pm

There is another way, of course, and that is to shim the Ohlins fork legs into the Aprilia/Marzocchi yokes. The Ohlins fork legs are only 1mm diameter less than the Marzocchis, I believe?

The simplest way would be to take one can of beer (choose your favourite, obviously), drink the contents, then set about the can with a pair of tin snips to make 4 strips of can about 15-20mm wide and 150mm long. Then use the strips of beer cans as shims to pack out the fork leg/yoke interfaces...

Syltiz · #15 Post by **Syltiz** » Tue Jun 09, 2009 1:35 pm

Wow you are up against it today

Cant help with any info... but if you need then I do have a spare top yoke for you. It is very manky but since you are stripping it anyway that wont matter. The best part is - I KNOW it fits cos it was on mine before the mankyness irritated me to buy another. You want it? I cant post it tomorrow so with you on Thursday?