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> first meeting for LS 914, Racing at the MG Classic meeting, Manfeild Park
returf
post Nov 16 2016, 11:58 AM
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While most of you guys are nearer the end of your racing season, we are just beginning down here in New Zealand. I finally managed to get my car to it's first meeting last weekend. A classic meeting that is in it's 31st year of running and right at my local track. Practice went well but i noticed that I still had the wheel shake up front under brakes. Race 1 was going well with a demon start but unfortunately a lower arm on the left front broke and that put me out for the rest of the day. Day two, and another good start and went from grid 18 to 9th before the first corner, gee it's got great acceleration!!! Race three and off to a flyer again but three corners from the chequered flag and an axle broke. But all'n'all a great start to the 914's racing. Here's a video of race three. check out the shaking. Once i get that sorted i'm sure i'll be able to brake a lot later.

https://www.youtube.com/watch?v=C4OPnfSt_Lw

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stownsen914
post Nov 16 2016, 01:11 PM
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You've got some serious straight-line speed there! What kind of hp is it making?

I did notice the shaking. I'm guessing you feel it pretty clearly in the driver's seat. Do you know what's causing it?

Sounds like it was a successful outing overall.

Scott
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Toast
post Nov 16 2016, 02:13 PM
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Not bad for carrying sway bars.
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Great video. Thanks for sharing!
Good luck and enjoy your race season!
Which LS do you have? Or should I say what are your engine specs. (I dont get to the Paddock very often)
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Andyrew
post Nov 16 2016, 02:16 PM
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Spooling.... Please wait
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Are you still running really low boost?

Car looks like its running great!!
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Andyrew
post Nov 16 2016, 02:17 PM
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Spooling.... Please wait
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Whats the red nob for, boost?
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returf
post Nov 16 2016, 05:04 PM
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QUOTE(Andyrew @ Nov 17 2016, 09:17 AM) *

Whats the red nob for, boost?

Brake bias to the pedal box. I thought it might have too much front brake on, thus the adjusting
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returf
post Nov 16 2016, 05:07 PM
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[quote name='Andyrew' date='Nov 17 2016, 09:16 AM' post='2423786']
Are you still running really low boost?

Car looks like its running great!!

Yes only 8lb boost Andyrew. engine wise all i have to do now is fit a rear sump, Sump to it as looking at the data from the ECU it was dropping off oil pressure on hard acceleration ( thank goodness I had fitted an accusump)
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returf
post Nov 16 2016, 05:14 PM
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QUOTE(stownsen914 @ Nov 17 2016, 08:11 AM) *

You've got some serious straight-line speed there! What kind of hp is it making?

I did notice the shaking. I'm guessing you feel it pretty clearly in the driver's seat. Do you know what's causing it?

Sounds like it was a successful outing overall.

Scott


Its a standard LS1 un-opened, with bigger injectors borgwarner SX 475 turbo and Link engine management. Dynoed at 527ft/lb torque and 525hp ATW. It's a great feeling after all the years building it to finally race with other cars. Can't wait for the next event
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wndsrfr
post Nov 16 2016, 07:24 PM
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Crazy fast, thanks for sharing--especially like the left hand shifting arrangement, cool.
I'm betting on a warped rotor or at least uneven bedding of the pads/rotors. Put a dial indicator against the front rotors & rotate them to check warp/runout. Bedding a new set of pads/rotors takes a series of hard stops & then a cooldown time of about 5-10 minutes & never sit still with foot on the brake if they're at all hot. Keep us posted!
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Cracker
post Nov 16 2016, 08:49 PM
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Another potential issue is a wheel out of balance. Did you mount the outside weights on the inside of the drum or lip of the wheel? If inside, it gets too hot there - you will need to mount them on the lip (and tape them too). I bet you will find this is most likely the issue. The date says 2013 - wrong? What gear box are you running?

PS: I just watched the video...you might BOTH rotors and wheels out of balance. That is crazy amounts of shaking. Keep us posted...

Tony
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flat4guy
post Nov 16 2016, 09:00 PM
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Wow that sounds great, wish we saw more 914's out this way.......
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returf
post Nov 16 2016, 10:58 PM
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I'll check it out in the next few days Tony. the rotors are new J Hook AP's and I bedded the brake pads in at Friday practice. I suspect that some of the problem may lay in the attachment of the caster arms ( too light given the torque applied when braking) but I'll let you guys know what I find re runout ect.
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returf
post Nov 17 2016, 03:24 AM
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I've been out to the workshop and with the steering wheel locked solid you can get sideways movement of the wheels. I'm picking this will be from the steering joint under the fuel tank. is there any aftermarket fix for this and do you think this may be the cause of my violent wobble that happens only under brakes?
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Cracker
post Nov 17 2016, 07:28 AM
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Ok. A couple other possibilities: 1) There are four bolts that hold the steering column to the chassis mount - make sure they are tight. These are located underneath the column in the two slots; 2) The outside bearing on the same rack (in line with the turn singal stalk) can wear/enlarge its retaining bore. Due to the notch for the signal cancel its far from a perfect design. I once used a band clamp around this bearing and it helped a great deal before fixing it appropriately.

Tony
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returf
post Nov 17 2016, 11:11 AM
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Sorry Cracker, I didn't answer your previous question re gearbox. Its a 6 speed from a Subaru STI V7.

My steering column down to where it goes through the body is all different from stock. it's electric power steering and all the uj's are late model and secure. I'll check rotor run out today. what's an acceptable figure?
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wndsrfr
post Nov 19 2016, 10:28 AM
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QUOTE(returf @ Nov 17 2016, 09:11 AM) *

Sorry Cracker, I didn't answer your previous question re gearbox. Its a 6 speed from a Subaru STI V7.

My steering column down to where it goes through the body is all different from stock. it's electric power steering and all the uj's are late model and secure. I'll check rotor run out today. what's an acceptable figure?

There's a good guide that you can download from Centric Stoptech on rotor installation. Shoot for less than.002"....closer to .001" or less is desired. If they're off, try taking them off the hub & advance them one or two lug positions & measure again....keep us posted.
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returf
post Nov 20 2016, 03:51 AM
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is this coupler shagged?Attached Image
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Cracker
post Nov 20 2016, 06:44 AM
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I don't know (I can't tell exactly from that picture) but something is...

Tony

QUOTE(returf @ Nov 20 2016, 04:51 AM) *

is this coupler shagged?
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stownsen914
post Nov 20 2016, 09:50 AM
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I would think that if the steering coupler were the cause of that violent shaking, that the car would be darting all over the road, and you'd feel strong shaking in the steering wheel. Even if it's not the cause of the shaking, you may still need a new coupler if you're seeing movement ...

If the shaking happens primarily under braking, I'd look at your rotors.
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Cracker
post Nov 20 2016, 10:26 AM
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Trust me on this...I had thought I had a mechanical failure earlier this year due to the violence of the vibration on my car. We looked at everything and missed the most basic culprit. I had thrown wheel weights and was out 8 ounces. Mount the outboard weights on the lip and tape. You might be very surprised..I believe I've mentioned this before.

Tony

QUOTE(stownsen914 @ Nov 20 2016, 10:50 AM) *

If the shaking happens primarily under braking, I'd look at your rotors.
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