Topic: Front end shudders

[Spear]

I posted a problem here over 12 months ago and received some good advice. My problem was that my K2 front end (steering) wobbles at certain speeds. Someone referred to it as 'shucking'. Anyway, I went to my accredited Honda dealer and asked him if he could put tapered bearings in the head stem to eliminate the problem. No worries, he said. So I booked her in to get the job done. When I picked it up I couldn't handle the damned thing. Easy to corner to the right, but on a left corner at low speed she wanted to head across the other side of the road. Bloody frightening, especially in traffic. I rang the dealer and told him the job was a shocker and could he come and pick the bike up. No. He was too busy. So, I gingerly rode it back (18kms) and put it back in his workshop and told him I would pick it up in 2 days. Went back 2 days later, took it for a ride and it was worse. He admitted that the original set of bearing he put in 2 days before were the wrong ones supplied to him and that he now had the correct ones in. Really? I told him I was not happy with it at all so he said the only alternative was to put in original Honda bearings. This was done and I picked the bike up some days later. It was now riding straight, but I still had a shudder between 45mph and 55 mph. He said he didn't know what else he could do, and asked me if the bike had ever been dropped. Now, that's a big question. The bloody thing is 33 years old and I've only had it for 3 years. What do you reckon? Anyway, despite the fact that he said that he had checked the wheels for alignment I decided to check that aspect myself, and I believe (if my eyes are any good) that the back wheel is tracking to the right ever so slightly. The markers on the rear of the swing arm are all lined up equally on both sides but I don't believe thay are accurate. What say you? I gonna get the wheels aligned and see if that helps. Meanwhile, does anyone have any suggestion for things to try or to look out for? A different tyre (tire for the yanks) has been tried on the front but that didn't change things. If I don't get it fixed soon I'm gonna retire it and buy myself a new Yamaha V4 1300 tourer. Ooh, that'll get some reactions!!

[Einyodeler]

Check for worn swingarm bushings,a lot of front end shimmy problems can be attributed to this problem. Also try looking for a different mechanic if you`re not doing the work yourself (he admitted he installed the wrong bearings because he didn`t have the right ones?),thats playing with your life.Most of the mechanics at the dealer weren`t even born yet or still in diapers when our bikes rolled off of the assembly lane and a lot of them won`t even touch them if they`re over 15 years old.Worn bushings will throw the back wheel out of alignement.

[Bob Wessner]

Given it only occurs in a limite speed range, this is probably not the problem, but you might want to check wheel balance also.

[SteveD CB500F]

This is the 1970's wheel alignment trick - try it; I've used it for years.

Tie 6 feet of string to the front wheel via a spoke and run it down the bike so that it touches each tyre in two places (ie front wheel front/rear and rear wheel front/rear)

Sit at the back of the bike and squint along the string, it should be straight. If not realign the rear wheel until it is straight.  You may find that to do this you have to disregard the markings on the swinging arm - don't worry, they're only supposed to be a guide anyway.

Once lined up, when adjusting the chain, just make sure that you loosen/tighten each nut by the same amount each time and the wheel should stay in alignment.

This only works on old bikes with skinny tyres - at least where the back tyre is not several inches wider than the front!

[dpen]

The method I use (which works on all tyre sizes) is to get two pieces of wood-equal size. Pencil in a series of lines about 1/4 inch apart & stand them either side of the front wheel just touching the tyre at it's widest point.
Now crawl like a lizard behind the bike & sight along the rear tyre. You have to move your head around so that the widest point of the back tyre (front & rear of tyre) are in line. Look ahead at which mark on the wood is exposed.
Do the same on the other side & then turn your chain adjusters slowly until the same pencil mark is displayed on both sides.
On my current K7 this means that the right hand adjuster is 3 swingarm notches further forward than the left.
Makes a big difference in tyre, chain & sprocket wear.
Finally, make a note (in your manual, tattooed on the dog or something) of the position on the swingarm notches so you don't have to do this every time you remove the rear wheel.

[SteveD CB500F]

Sounds interesting but I can't visualise what you're trying to say.
Can you do us a photo?

[cben750f0]

how ong has the front tire been on?... i had a similar problem with the F1... and it turned out to be a worn fron tire....changed the tire... all was good... just a though.. tires are like anything made by man... not perfect... and if it is slightly defective from factory, then the more it wears the greater thos defects are going to have an effect on the motorbike.... OH and check the balance... peace

[Spear]

Damn - ain't there a lot of solutions to eliminate until you get it right? Let's look at a couple of your replies. The front tyre - as stated, the tech fitted another (not new) tyre and still had the same problem. I don't think the wheel was checked for balance. I had new swing-arm bushes etc fitted 18 months ago - and the bike does not do a lot of miles, about 2,000 a year if I'm lucky. Now getting back to wheel balance - I know that my rear wheel is 'slightly' out of round. I know this because when I lube my chain I have the bike on the centre stand and I idle it in 2nd gear to spray. I can see the flat spot. It's within the wheel, not the tyre. The tyre is only 12 months old and done about 1,500 miles. The tech said "It's not that bad. You can't feel it when you're riding so it's not affecting the ride." Sounds like a bit of bull to me. I think I'll have to pull the rear wheel off, remove the tyre, and have it re-spoked to get it round again. That'll eliminate that aspect. I suppose then I'll get both wheels balanced perfectly, and ensure the wheels are aligned. If that doesn't do it then the Yammie is looking a better prospect every day. Thanks guys. I'll let you know how I go. BTW just came back from a 3 days ride with my brothers and my speedo crapped itself. Needle dropped to zero. Undid the cable at the speedo and it was still all there, so I did it up again and rode home on the tacho. Had more fuel stops that I needed because obviously my trip meter and odometer weren't running either. I'll take the entire cable set up out this weekend and check it. One of my brothers reckons it sounds like the inner cable has actually broken. Hmmmmmmmmm! Oh yeah - one more cable story. When on the 3 days ride, I heard this whirring sound when I was sitting at the lights on idle. Sounded like 1,000 wasps in the rocker cover. Took it to a bike shop and the mechanic had a quick listen as it idled and buzzed away. Straight away he said, "Your tacho cable's dry." He loaned me a pair of pliers and a can of spray oil and bingo - problem fixed. (And he was a Harley mechanic. Must be used to these annoying problems!!)

[Bob Wessner]

Do let us know what fixes the problems. Often a number of possible solutions are posted, but the original submitter doesn't always come back to let everyone know, and that's how we learn.. er, at least how I learn. I'm guessing the original posters are just so da_n glad to resolve the problem, they move on. Good luck.

[Spear]

Thanks Bob, will do. We 'corresponded' some time in the not too distant past. What was that about? Obviously SOHC stuff.

[Bob Wessner]

To tell you the truth, I don't recall the subject matter either other than it being SOHC related. I've had my share of them, so God only knows which one it might have been.

[dpen]

Bob, the method of aligning the wheels with the wooden blocks is basically the same as sighting along a straight edge (length of wood or steel) touching both tyres (details in most manuals). Due to centre stands, four-into-ones & assorted crap, a straight edge most times won't fit. The wooden blocks substitute for the straight edge.
You don't want to know how many beers it took to figure it out!!

[Spear]

Bob. I think you might have asked for the "SOHC IT TO ME" poster? Yes?

[Spear]

Truth time today. I spent some time yesterday in the workshop lining up my wheels. And guess what? - It would appear that the rear tyre was not properly aligned (despite the assurances by my bike tech that it was). He had obviously relied on the register marks on the rear of the swing arm being accurate. He had aligned the wheel on those marks - very nicely aligned too. However, a blind man on a galloping horse could see that it was pointing to the right, and not just by a little bit either. So, using some 2.4 metre lengths of aluminium extrude I checked the alignments and brought the rear wheel back into what I consider to be "dead straight ahead". This afternoon I'll take her for a ride down my road. I have a 100km/hr speed limit at my front gate and it is a lovely rural road  SO I CAN DO WHAT I LIKE!!! Wahooooooooo! Let you know tonight how it goes.  Oh yeah, pulled the speedo cable out and it was broken about 12" from the top. Checked th outer cable as well and there was a breach of the plastic outer sheath, a slight kink in the inner cable at that same point (which funnily enough aligns with the break in the inner cable - now fancy that!) Musta got some sh!t in there through that breach which over time has aggravated the inner cable enough to make it snap. So back to the front end shudders - hopefully today they are gone. Won't that be nice?

[Spear]

Well - it's not the wheel alignment. I'll now have to have the wheels balanced to eliminate that aspect. Damn, that new Yammie is looking more attractive every day.

[cben750f0]

classic mate... classic.... not the yammie!!!!  when its sorted you wont know wot all the fuss was about... you'll see:P...peace

[Spear]

I know Ben, I know. Actually, when I do buy the Yammie in a couple of months it will do the K2 a world of good. You see, once I'm mobile on the Yammie Venture I will be taking the K2 off the road for about 6 months and dismantling it. I'm going to pull it into a thousand pieces, blueprint it and put it all back together again. I wanna have the frame painted with 2-pack, I wanna re-wire it fully (not with an OEM harness, but one I will weave myself) and replace all the lights except the headlight with LEDs. You know the sort of thing a bloke has to do.  I have the obligatory, built-in oil leak somewhere underneath that gives me a nicely oiled left toe cap when I'm touring as well as the customary oil weep around the head gasket. Nothing bad you realise but I just wanna get rid of them forever. The pipes are as good as new - actually I bought them from a bike mechanic in Lavington a couple of years ago. Damn, I forget his name but he was across the road from a shopping mall and 2 doors down from a set of lights there. You may know him? Meanwhile, as long as I have both hands on the bars the shudder isn't too bad. Actually, it's more of a wobble than a shudder. Either way bloody annoying!  BTW here is a pic of the latest safety feature on my other bike - airbags!!

[mick750F]

   Airbags!!! I knew there was something missing on my bike.

[Mark M]

This is an observation rather than any kind of solution to your problem.

All bikes have a speed at which they 'get a bit twitchy', this is normally such a low level that the rider won't even notice. It's generally in the range of 35-50 ish. On any bike you can find it by sitting up and taking your hands off the bars and as it decelerates at some point you will see the bars start to shimmy. All bikes will do this. If your getting it twitching so much that you can feel it with your hands on the bars then I wouldn't advise taking your hands off, it could go into a lock to lock slap. My sidecar outfit will do this quite violently if left to build up at about 30mph. It's a bit like shopping trolly wheels, if the frames bent or the wheels kinked it will flap arround like a mad thing, but if everythings set up square and true it tracks nice and straight and you can control the trolly.

You have already covered most of the variables, basically all the chasis/wheel bearings, the wheel alignment, the tyre itself. The wheel balance and runout are two possable contributors as they both affect the gyroscopic action of the wheel. Even quite small irregularities can have a big effect which can be tuned to a particular speed range.

Anyway goodluck.






   

[cben750f0]

that bike mechanic in lavington is AL!!!!!  top tune... he is the only other bloke that works on the F1 other than me... top bloke... will stop whatever he is doing to have a look at the o' girll... i mean just down tools and poke,fiddle,tweak... cant speek more highly of him.... GAVE me a set of F@ carbs...emotion tubes for the K/F carbs, hole number three carb body,will service the old girl for 60dollars(including filters).. he is a ledgend... and there is some really interesting stuff in the shop.... PEACE

[DRam]

Something that hasn't been mentioned so far is tire pressure.  The Sport Bike Web Site (www.sportbikes.ws) had a thread about front end wobble.  That rider cured the problem with an extra pound or two of air in the front tire.  Just one more thing to try.  Also, if you replaced your original tire with one that wasn't new you may have put another wobbler on.  Some bikes are reputed to be sensitive to tire condition, although I don't know if the CB's are.

[Spear]

Gee guys. Any wonder I'm part of this forum. I'm overwhelmed with the responses. Anyway, today I took the machine for a ride into town (I live 17km / 11miles out) and went straight to the Yamaha dealer [don't hit me!] from where I will be buying my new tourer. He has a pretty good workshop and has a number of blokes (and gals) on staff who ride BIG road bikes. Pulled up in the workshop and told them of my woes and problems. Straight away the bike was on the centre stand and the run of the back wheel was checked. The slight flat spot I had that the Honda technician said was not a problem, was compounded by a slight side to side deflection that I was not aware of until it was pointed out. Not good!. They then looked at the front tyre and noticed that the tread on one side was scalloped. Not so on the other side. Caused by the 'wobbles'. They said that they had only recently acquired a brand new dynamic wheel balancing machine, and would balance the wheel for me. They also said thay had a specialist who would re-lace the back wheel for me and correct its out of round and run-out. It was suggested that I put a brand new tyre on the front after all this was done. The rear tyre is 12 months (3,000km) old - or new? I spoke with Dave (Hop On A Honda) the other night who suggested that any dynamic balance should be done with low pressure in the tyre/s to enable the tyre and tube to 'centre' themselves whilst spinning on the balancer. When I told the guys in the workshop this they said they were interested in this principle and would certainly give it a go. Anyway, I've committed myself to keeping my trips to a bare minimum from now until I have the problem sorted out. It's getting cooler here in Oz now - not cool enough to stop me riding - but when winter sets in with its usual vengeance I'll get the job done. It doesn't snow here but it does get down to -5degC some nights and lucky to get to 5 or 8 during the day. So what you say? Well, how's 45-48degC in summer sound? Man that's so hot that you CANNOT ride a bike. Too hot for leathers or any other sort of outfit, and if you wanna ride in a tee shirt your arms burn in 5 minutes flat from the sun and wind. Any wonder I love spring and autumn. All right, looks like there will be no updates for a couple of months, but they will come.