07 GSXR 750 front vibration

This was a street bike with 7000 miles, never crashed.

I turned it into a track bike last winter using 95% new parts.

Earlier this year, i had a terrible vibration in the front, at all times. Not just under braking. I parked it, and rode the other 2 bikes for the wknd.

Bike has the following to consider:
2012 GSXR 600 forks with Ohlins 30's (fresh)
Penske triple (fresh)
GPR V4 (new)
Accossato 19x18
09 GSXR 1000 monoblock calipers
EBC GPFAX pads
Dunlop's race DOT's

I do my own tire changes/balancing at home so i thought maybe that was suspect. Double checked all that and was convinced that i was good to go, but the rim did have an ever so slight wobble, but within spec. Nonetheless, i sent it and another rim to Wills. They were so close to being true, that he barely charged me anything...maybe $20. ( i gave him an extra $50 though, karma right?) He got them within .001 he said.

Fast forward to the next event with the newly straightened front rim and bike felt much better, but still some vibration. I took front and rear rims off, had them both balanced by the Pirelli vendor at the track. Bike still felt the same.

Fast forward again... I have a fresh (0 miles) set of 07 GSXR 750 with Ohlins 25's and extenders at the house, so i made the swap. Swapping the forks meant swapping the rims too.
I checked the triples....forks slide in and out easily. Everything torqued properly. I went through the head bearings and set them accordingly....proper torque on stem locknuts, etc....

Went to NCM and vibration is still there and worst than before. Parked the bike again.

Get back home, and swap out the 08 rim with the original 07 rim and rotors that is in mint condition and not a scratch on it.
Double check everything....motor mounts, triples, calipers, wheel straightness, wheel balanced, proper torque on everything.

Next event, vibration still there but not as bad as NCM. I parked the bike again.

Fast forward to today....My next plan is to swap out the 09 calipers with another set of 09 1000 calipers....Maybe i have a sticking piston?

I'm just going through the process of elimination by replacing/swapping parts. The calipers are the last thing i know that it could possibly be.

Thoughts, ideas?

 

Is the vibration speed related or RPM related?

 

No. on track, at any speed, straightaway or turns.

It seems worst at straightaway speed.

This past wknd, i would look down thru the fairing at the lower fork and wheel and could see the fork pogo-ing. The vibration would transfer directly to the clipon and bar.

In the garage mow, and with the wheel off, i put shims in the calipers and watched the pistons. Should all 4 pistons on each caliper move in sync? Common sense tells me yes?

 

I had an experience where my FZR broke the clutch basket and a couple of fingers broke off. Clutch use was barely affected (80hp, so not a big burden on the clutch), but the vibration felt like the front wheel was out of balance/rotors warped/everything but the engine.

I know it's different, but if possible, put the bike on a dyno and see if it vibrates. That rules out front end issues, plus you get to check the mapping. Or whatever. But if there is a bike night near you, or a shop with easy access, it might be worth it to dyno the bike to remove variables.

 

Let me reword that...
Does the frequency of the vibration vary with speed, or RPM?

 

Next time you're out disengage the clutch and see if it goes away.

 

I understood your question as that. My response probably needed re-phrased.

Did not affect the vibration/shaking.

After your thoughts, i went out and got on the bike while on the stands. Fired it up and watched the back wheel spin in lst gear and could clearly see a 'hop' in the tire, not the rim. Checked the tire and couldn't see a bulge or anything unusual.

Got back on the bike and banged through the gears. The vibration was there big time and got worse as MPH climbed...which explains the more violent vibration at higher speeds on the track. That 'hop' on the tire was more on the right side which it definitely shook more in right turns.

Took the tire off and there is a small 1/4" cut in the bead. Don't know if that cut damaged a cord/steel belt or whatever, that extends across the right side of the tire and caused the apparent damage. No other visual damage that i can see.
Footnote: Tire vendor had 5oz's of weight on the rim....(10) 1/4 oz weights on each side of the rim.

So, put another tire on, same brand/size, balanced it, took less than 2 oz's.

Got back on bike, banged through the gears and vibration is gone. Lets call it, the 'shaking' is gone. It was way more than a vibration.

Tire vendor was the last to have hands on the damaged tire when he flipped it and rebalanced it. I assumed if there was an issue with the tire, it would have been seen then, so i didn't think muuch more about it. I probably damaged the tire when i originally mounted it.

 

Let me guess...Dunlops.
Oh, right...see it at the top. Why didn't I have the presence of mind to just point that out?

 

I know i know. I"ve tried to love Pirellis on the RSV4 just can't get used to the feel of them....ran stones on the SV's in endurance....michelin, eh, not so much....have been a Dunlop guy since forever.

Every wknd i consider the Pirellis again....Might try the Bstones V02 next year too....

 

Curious if you're referencing a specific issue or if you're justat Dunlop.

I've recently also had some issues with a certain model of their tire. I will say that their customer service has been very good.

 

Kinda both. I can't speak to their stuff in the last 3-4 years.
My issues were short life (other than the Q series), highly unbalanced after use and delamination.
They're not cheap for that level of competence.

 

Sorry, but 5 ounces of weight should have been a red flag to begin with. I'm surprised something wasn't said at that juncture.

 

Yeah...each stick on weight is 1/4 once I believe.

 

The tire vendor said it was 'normal' for Dunlops. I raised an eyebrow for sure, but what do i know...he's the expert.

I assumed if he got it balanced, then it's balanced. Whether it's 1/4 oz or 5 oz.

 

After the first one, I was never again surprised to have to put 8-10 weights on a D rear...par for the course. That really bothered me. When I got some use on the tire and figured I'll just flip it, keeping the tire indexed to the weights I just stuck on there two days before, thinkin' it should all balance out...
Nope. I had to remove those weights and put nearly the same amount of weight on the opposite side of the rim! WTH? Less than ten sessions and the balancing weights (not just two or three, but TEN) need to be moved 180º out? How effed up does a tire's quality control need to be in order to require more than two ounces of weight to start, then finish by relocating the balance point with that same amount of weight 180º out?! Seriously...WTF?
(Delamination is just the gravy from running a wildly unbalanced tire.)

In contrast, Pirelli and Michelin, I was always surprised to use less than two weights on average, <1/2 oz. In some cases, it has been less than a weight and even had a couple requiring zero balancing. In other cases, I had to cut a chunk from a third weight. Big whoop, 5/8oz to balance.
When flippin' 'em, most cases called for the removal of the weight(s) - no further balancing necessary.
Other than getting suspicious of their tires if they take four weights, I don't have any issues with Pirelli or Michelin QC.
(In fairness, I have delaminated some Michelins but only the street compounds.)

 

8-10 (.25 ounce?) weights presumably?

I don't balance a lot of bike tires, but the ones i have were all less than 3 ounces, actually a lot under. If they were over that I'd be asking questions or sending the tire back. I do car tires and 3 ounces on a car tire isn't abnormal but a really good tire will be less than two on each side (for dynamic balance). Big mofo tires that need tape weights (especially for the outer side) are placed inboard of the hub which ultimately make it need more weight, sometime can see 5-7 ounces and that's a LOT of weight, but the equivalent to it being on the outside may only be 3 or so. I guess ya never stop learning, glad it didn't end up with you in the weeds! Balance IS balance, but you can balance a square too, still needs to be concentric and everything else I'm never going to understand as there is a lot more to is than meets the eye (as is with anything).

PS- Michelin car tires have saved me more money in wheel weights than any other brand.

 

So (20) 1/4 oz weights on my rear would have been a scorecard riddled with a shit ton of bogeys?

 

ive used a lot of Dunlops the past few years. more often than not, the weights go back near the same spot and dont change much, implying the imbalance is with my wheels. the only time i had one vibrate was because the tech mounted it backwards and used the wrong cones, so it was balanced on my captive spacers. it was a front of course since the rears arent directional anymore.

i regularly spin tires on the wheel a little bit. i think the worst ive done is 1/4 turn over a race. but they still dont cause a vibration if i use them again after that. i gotta assume literbikes and harder brakers could spin them further. thatd cause them to be slightly out of balance. but of course, if the majority of the imbalance is in your wheels, it wouldnt matter.

random thought. if the tires are mounted with the heavy or light spot so that it balances out the wheel, then maybe tires that get very little weight are actually more out of balance than ones that get a bunch of weight. unless uve balanced your wheel without a tire, u cant know.

 

After going to Jennings last wknd, I can confirm that my problem was indeed a bad rear tire....which could have easily been damaged when i mounted it myself.

Bike was as smooth and fast as i could make it go.

 

Hooray! But even if you put a small nick in the bead it shouldn't take 5 oz. and next time get with the tire vendor ASAP!