Motorcycle Racing Forum

Racing Discussion => Racing Discussion => Topic started by: Speedballer347 on June 26, 2006, 02:45:36 PM

Title: Excessive front tire wear....can it be suspension related?
Post by: Speedballer347 on June 26, 2006, 02:45:36 PM
Putnam Saturday, 06/gsxr1000.  Thermosman front and Ohlins rear.

In the morning....
Front end was pushing (not sliding), but NO front tire wear.  No confidence so I didn't lean over very far or stress the front. Bike was also steering a tad slow and running wide on exit. 

Afternoon...
At the advice of MDR, raised the rear shock length 2.5mm.
Bike immediately felt great, felt completely nuetral.  Steered quicker.  (could have steered a hair quicker if I was nit-picking) After approx 6 laps front tire (that looked great 6 laps before) looked and was torched.
Next session both ends started sliding almost every corner at lean angle.
One more session and started tucking on trail braking, pushing front at lean angle, pushing front on exit (all the way to edge of track), and spinning rear (expected this...not abnormal).  Front end started pushing more and more.

I understand tires wear, but strange that no front tire wear until I corrected the geometry, then immediatly fried the front and started progressively pushing the front more and more.
I expected the 1000 to fry the rear, but this is the opposite....rear tire is worn....front tire is fried.
This bike just ate the front tire.
I have ridden putnam much faster on my 600, chewed rears to pieces, but never had a front Pirelli do this.

Suspension felt very compliant over bumps.

One more thing, There is still a front chicken stripe on the tire (meaning I wasn't leaning over as far as tire was capable), but tire is ripped up severly at chicken stripe border.  Why would a tire that is not being leaned over all the way on, rip up like this?

Wacked out suspension in the front???  Advice???  I really want to get this bike set-up right.  Seems to handle pretty darn good.  Just ate the front abnormally quick, and started pushing the front again.
Any advices?

Front:
(https://www.ccsforum.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv405%2FSpeedballer%2FDSC01298x.jpg&hash=0d5ccadf4b45f6d5333274c5c2cc54311f0c55a8)
http://img.photobucket.com/albums/v405/Speedballer/DSC01298x.jpg

Front chicken stripe:
(https://www.ccsforum.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv405%2FSpeedballer%2FDSC01299x.jpg&hash=2039e6fb27badad50a623cf90b3d4ef2eed87ddb)
http://img.photobucket.com/albums/v405/Speedballer/DSC01300x.jpg

Rear:
(https://www.ccsforum.com/proxy.php?request=http%3A%2F%2Fimg.photobucket.com%2Falbums%2Fv405%2FSpeedballer%2FDSC01296x.jpg&hash=fa36e06a05b25dd513725693bbdaf46a65400cad)
http://img.photobucket.com/albums/v405/Speedballer/DSC01297x.jpg






Title: Re: Excessive front tire wear....can it be suspension related?
Post by: tstruyk on June 26, 2006, 03:39:33 PM
not enough stoppies....  :boink:









I'd start simple... tire warmers (I know you have em... where they plugged in  :kicknuts:)
Tire pressure?

then when I get funny tire wear I always try the same thing.... "RYAN.... HELP"  :ahhh: seems to work everytime.  Did you try calling t-man? 

To me thats part of the cost... service follow up.

Rebound issue?  fack I dunno...

Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Jeff on June 26, 2006, 03:46:21 PM
damn...  that front is definitely shredded...

I'm no suspension expert, but I have been getting smarter over the years.  Typically when I see a tire ABNORMALLY wear like that (abnormally as in, a new tire. Not some tire that's 2 years old and been sitting in your garage), I find that the rebound is too quick.  That however, is typically on the rear.

On the front, I don't know...  I suppose if the rebound was too fast, it could shred the tire as you get on the gas and the front tire chops out over tiny bumps, but at that point the bike should be running wide.

Were the pressures right?  Very weird...

Also, what track were you at?  HPT is a HUGE front end track.  BHF is not...
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: K3 Chris Onwiler on June 26, 2006, 04:14:24 PM
What were the temps like?  And how about the air pressures?  Looks to me like the tire got hot.  2.5 mm rear raise in the rear is damn near nothing.  It doesn't make sense to me that 2.5 mm of rear ride height would make such a vast diffewrence in the handling.  Raising the rear would have transferred weight to the front tire, but 2.5 mm?  That is like what, 2 threads on the shock clevis?
BTW, You edge the front under trailbraking, and Putnam just isn't a trailbraking kinda track.
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Super Dave on June 26, 2006, 04:50:42 PM
I know current Pirelli tires are different than Pirelli tires of last year.  Seem to be softer, and the only recommendations on pressure are given based on the tires being warm that I have heard of.

Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Clay on June 26, 2006, 05:09:19 PM
You need to get with a supsension pro on that.  It could be a # of things.  Lovely advice, I know.  The tire is tearing though, and that's an obvious sign of something gone wrong. 
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Speedballer347 on June 26, 2006, 05:11:33 PM
Thanks for the comments fellas!


Quote from: K3 Chris Onwiler on June 26, 2006, 04:14:24 PM
2.5 mm rear raise in the rear is damn near nothing.  It doesn't make sense to me that 2.5 mm of rear ride height would make such a vast diffewrence in the handling. 

I'm educated guessing at the 2.5...actually, I turned the shock clevis exactly 360-degrees (one rotation) to lengthen it.
CH tire warmers. 31 front, 29 rear cold psi. Sunny and hot. 
New Pirelli Blue front.  Last year model from Tigershark.  VERY good tire, no complaints.
Just wore out fast and then exponentially continued to wear out.  Once it started to go, the front tire was predictably sliding the front from once you would lean it over all the way to exit.  Tucked once pretty bad on me in T2, but the bikes' feedback is so good it wasn't a big deal.  You can truly feel everthing the tires are doing on this bike.

Once the rear was raised, bike is 'was' very nuetral until tire fried.  In fact, I don't think the nuetrality changed, but instead the front just started sliding (more than the rear) because it was wearing faster than the rear.  Never even leaned the bike over all that far (hence the chicken stripe).

Front rebound is kinda slow, not bad but just a tad slow.  I have the adjuster all-of-the-way out, so can't speed it up any more.

Should I raise the back up more?  Maybe raise the front a hair to relax the geometry and then raise the back up a bit more?

Other than wearing the front out fast, no complaints with the bikes' suspension.
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Super Dave on June 26, 2006, 05:20:29 PM
Quote from: Speedballer347 on June 26, 2006, 05:11:33 PM31 front, 29 rear cold psi. Sunny and hot. 
New Pirelli Blue front.  Last year model from Tigershark.

I'd check your guage against one of the Pirelli vendors so you have an accurate ruler...and I'd find out more about the hot pressure thing. 

Blue is the really soft tire, right?  I know some guys in Topeka were killing them, the soft Pirelli.  Was hot there too, and using other tires, we have had really good luck running softer tires...might be a function of the carcass or something.
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: mdr14 on June 26, 2006, 07:18:28 PM
For the most part the answer is " Welcome to Putnam"

If I am running a soft tire, I will see that.

Putnam has a lot of high speed right hand stuff that will tax a front tire. That is normal to see what you see.

I really did not pay attention to see how fresh that front tire of yours was, but I can take a brand new soft ( Pirelli or Bridgestone) and see that type of wear by the fourth or fifth session. But the Bridgestones still grip in that condition.

Perhaps a better setup on the front can minimize that.
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Jeff on June 26, 2006, 07:23:51 PM
if your rebound is slow and you have the adjuster all the way out, you need to get some work done on those forks.  For me, that would be an absolute showstopper...
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: ccs117 on June 26, 2006, 08:30:37 PM
I'm running Pirelli and had some similiar problems last race weekend.  Pirelli said cold pressure 26 rear and front 28.  I'm guessing you have too much weight on the front and raising the rear only compounded the problem.  I lowered the forks in the triples and that helped me greatly.  Just my two cents.
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Gixxerblade on June 26, 2006, 08:34:16 PM
26 R 28 Fr? Where were you at? I was at VIR this weekend where it was kinda cool in the morn and the Pirelli techs told me 31Fr 29R.
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Speedballer347 on June 27, 2006, 12:05:28 PM
Quote from: Jeff on June 26, 2006, 07:23:51 PM
if your rebound is slow and you have the adjuster all the way out, you need to get some work done on those forks.  For me, that would be an absolute showstopper...

The Thermosman did them. I hate to send them back and have to wait again.  Man, I dunno.....the bike feels sooooo good other than the front tire wearing fast.  :ahhh:
I'll check my guage and talk to Tigershark about overheating issues like Super Dave says, and I'll also keep in mind what Drucker said.  Perhaps switching to a Green (soft) instead of a Blue (supersoft) will cure it all.

Thanks for all of the advices!!!!
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Speedballer347 on June 27, 2006, 12:11:49 PM
Ooops...forgot to add....

In regard to transmission issues with this bike.

Bike shifted great on the street during break-in.  Then wouldn't shift into 5th and then 4th gear as soon as we took it to the track.  The only thing I had done to the bike before we track'd it was change the oil (Castrol GTX 10-40).
I dumped the Castrol and put Honda motorcycle 10-40 in it, and after a session at Putnam it started shifting correctly again.  Transmission seems fine. I suspect for whatever reason the oil was keeping the clutchpack from seperating/disengaging when I would pull the lever.
Problem seems to be gone  :cheers:
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Super Dave on June 27, 2006, 12:40:14 PM
Motorcycle transmissions are simple.  It should shift as long as the load is removed from the dogs.  That can be done by letting off the throttle, using the clutch, or cutting the ignition. 

Are you holding the bike WFO and fanning the clutch?
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: Jeff on June 27, 2006, 01:36:04 PM
If the rebound is that slow, there is something wrong with the setup and I would question the entire job.  Thermosman is (from what I can tell) a very reputable shop.  They likely will not have an issue looking at them again for you. 

Transmission...  Oil is not your cause (so long as you have some).

1.  Did you change your shift pattern to GP?  If so, the angle on the heim joint may be off enough to cause a problem.

2.  Do you have rearsets installed?  If so, there could be an issue with binding (even slightly) which can prevent the shift rod (through the motor) from returning all the way to allow the plate on the end of it to engage the star again and hit the next gear.  I run into this every now and again.

But again oil, especially a like viscosity will not cause a shifting problem.
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: barryd on June 27, 2006, 08:54:39 PM
Super soft front at Putnam on a hot day is a bad choice... BAD choice
Title: Re: Excessive front tire wear....can it be suspension related?
Post by: joewambo on July 02, 2006, 04:05:37 AM
    Putnam is my home track, been there many times on a  03 gsxr 1000 before turn 8 (dead bear) guardrail claimed it.  The best setup i could find was the front forks raised 10 mm in the triple clamps.  Rear penske 4-5 threads from bottom with 10 mm of spacers on the shock mount because i was using a 180/55 tire.   I ran #5-6 compression on the shock. (penske shock)  Rebound was 13-15 clicks out from full stiff.   I gained two seconds at every track i went to including blackhawk after putting the shims in the rear to make the geometry more aggressive, but it was a 180 tire on a 1000 rim.  I used to burn up rear tires that looked like your front except worse at putnam until i made the geometry change.  After this the tires wore evenly with no tear on either front or rear.   In the end i was running mid-high 1:14's consistently.  I must say one thing though,  the track seems to have less grip every year especially if the temperature is high.  The pushing your feeling may be because of the grip of the track itself.  I went there probably a month and a half ago on a 85-90 degree day and slid all over the place,  so it may not be your geometry only the track grip.  Every one
there that day was complaining about there lap times being @ 1.5-2 seconds slower than usual.   Track temperature was above 120 degrees.  I've heard that the 05-06 gsxr steers much quicker than the 03-04 so aggressive weight on the front may not be the answer.   Looks like cold tear on the front due to the paralell lines to the rotation of the tire.  Maybe take a couple pounds out of the front.   Anyway i hope any of this helps you. 


Joe  #530 expert MW