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Discussion Starter · #941 · (Edited)
We finally managed to set new PR on Grobnik Track Day, with a lap time of 1:36.384. The handling was spot on and the focus was there.

Thanks to entire GMS crew and our business partners for helping us reach a new milestone.

Vargalant, VPS, Ana Gale, Boštjan Murn, Enigma - Tuning Performance & Maintenance, Ninety9 Works, David Lazar Nitron Racing Systems Ltd, Alfissimo International and all the supporters.

At last but not least, a special thanks goes to all the GMS customers which fuel us to further work and develop this amazing car that ALFA ROMEO gave us. The 4C.
Thank you all, we couldn't have done it without you.
🏁



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Discussion Starter · #944 · (Edited)
Honestly, when car handles like you want it to and have trust in it, a common size cojones will do just fine. Rest is the mindset. To drive on the limit, relaxed, smooth, at subconscious level. To flow through the track not drive on it thinking about speed, braking points, apex points, possible crash etc. You must complete the lap without even knowing you've completed it. For me it's the easiest way to get to this level of performance by chasing cars ahead. It really sharpens my senses and performance. Of course, not every event I perform at such level even if I would like to. Sometimes I just feel off, but the more you race the more you drive, the easier it gets to get past that barrier when you face it and get in the flow even if it feels a bit off at first. Just don't go full attack if you don't feel like it. It's a great chance you'll end a whole event trying too hard, forcing, resulting in disappointment. It happened and it still does to me sometimes. Especially when we do lots of changes to the car and can feel the improvement, but just can't benefit from it because I'm trying too hard. Sometimes you just have to let it go and back up, relax a bit and give it another try next time.

Also, it helps me a lot to get rid of distractions like data loggers, cameras and get rid of talking to people during pitbox time. I just have to be in my own world. Just a pilot. I highly suggest not to bother with lap times during the event because wishing for a good lap time won't give a perfect lap, but perfect lap will give a good lap time. Looking at the clock just takes away your focus. Entire lap must be driven at such a high level of focus and performance that you can't replicate it by simply driving it at conscious level. You must get to it.

Something like that. I find it hard to explain. I have no clue or talent about electric guitar but I love it. Especially electric guitar shredders and when you listen to the best of the best, they actually just play, they perform. The sounds, the vibes, the movement of fingers. They don't think about it. It's the flow. That's what brings the perfect lap.
 

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Discussion Starter · #948 ·
Engine is out for:
  • Clutch replacement (will be testing custom made clutch made of Kevlar by Slovenian company Sinter, specialized in clutch and gokart brake pads fabrication. Estimated to withstand about 30% more torque and, longer lasting and far more heat resistant. I hope it will work OK.)
  • LSD (Not sure yet whether I should put in Wavetrac or clutch type Drexler. Got both on stock. Heart says Drexler, brains say Wavetrac.)
  • Timing belt and water pump replacement
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P.S. The timing belt was still perfectly fine after 5 years and 50.000km of mostly spirited driving.
 

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@GMS why should Drexler be better than Wavetrack? Does the latter lock with less difference in axle speed? That said, I know Drexler work excellent, just not for so long.
 

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Discussion Starter · #950 · (Edited)
@AAaF Drexler should be more predictable to drive with constant 30% acc. / 40% decc. lock, while Wavetrac is still a torque biasing LSD, resulting in variable lock values.

So yes, I've opted for Drexler LSD and hope it will last more than 1 season before needing a rebuild. Ideally would be to last about 40-50kkm, when the clutch will probably need replacement again. I also hope it won't promote too much push understeer. We'll see...

The build quality on both LSD's is very good and precise so no re-shimming will be needed to adjust the backlash on the ring and pinion.

Gearbox shafts:
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OEM open diff vs. Drexler clutch type LSD
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The old pressure plate and clutch had decent signs of wear. Actually the pressure plates shows strong signs of overheating and glazed surface. As the surface gets glazed, the friction between the pressure plate and clutch plate greatly drops, so the clutch slips easily, but it usually doesn't smell. The wear on the clutch itself is not very bad, but if you look closely you can see uneven wear, again cauzed by glazed pressure plate. In such case, replacing the clutch without replacing the pressure plate wouldn't be the best idea as the clutch slipping would reoccur sooner or later.

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We miss out on Rudi giving us Wavetrac info, tips, tweaks, GMS Wavetrac bias plates… :(
 

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Discussion Starter · #952 ·
@FLORO Well've just ran into Drexler fitment issue, so it might be that we'll be installing Wavetrac instead, I'm not sure yet. I've just sent an e-mail to Drexler and look forward to hear their explanation. Luckily we noticed the fitment issue before fully assembling the transmission or let alone the whole car. It's not unsolveable, but still for the high end LSD unit as Drexler this shouldn't have happened. Now modifiyng the oil guides and the transmission housing is not exactly the best solution as the LSD could have been designed to not cause these issues.

Oil guide clearance issue (the bolts interfere with the oil guide - at least 5mm of clearance is missing)
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Transmission housing clearance issue (the LSD housing interferes with transmission housing - about 2mm of clearance is missing)
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OEM open diff vs. Drexler LSD

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P.S.: I'm glad that we've tried this before selling any to the customers. It's not like the end of the world as it can be solved, especially if you are aware of the potential fitment issue, but assembling this and failing to notice the fitment issue, could result in transmission issues or serious damage and honestly it would be hard to prove that there was an issue with LSD in first place and workshop would be blamed for, which by the way it is actually, as they should notice this in first place, but still, buying the most expensive LSD unit on the market and coming across such issues is not exactly what we've been expecting. I'm a bit disappointed at this point, but we did made a few fitment failures too (rear control arms with different type of undertrays), so I know what's it like to develop a part to later find out that it doesn't fit all the 4C cars, even though you tried your best to offer a premium product. Let's see what Drexler has to say, before making any further conclusions...


I still believe it's a good LSD if not the best, but...

Our car is now disassembled in our garage and can wait there, but if this would happen to a customer, neither the customer or workshop would be most pleased to have the car staying there until things are sorted out.

BTW @FLORO, what's your status with the transmission issues after LSD installation?
 

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BTW @FLORO, what's your status with the transmission issues after LSD installation?
All sorted. I know I got a bearings and the clutches repkaced and it’s all 100% good now. There was no issue with the Wavetrac or caused by the Wavetrac.

This Drexler fitment issue reminds me of the KW coilovers. Like you were deciding between the Wavetrac and Drexler, went Drexler, having issue, wondering if should of gone other way…. Exactly like me and the Nitrons when I was waiting ages for KW to get their shit together. I thought about bailing and getting the Nitrons but stuck with the KW and glad I did because they ride brilliantly.
I think you have to see it through, whatever I would of preferred personally.

Bias ratio is the issue. Your Drexler will put more power down in tight turns I suspect. I bet tyre wear will be greater.
 

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What exactly? What are the symptoms?
If I understand it, with the Wavetrac there will be tight corners where it will put less power to the wheel with most grip then your Drexler will. We would need different different bias plates to optimise for track.

edit - They say they are sold separately but I haven’t looked into it as the supplied carbon plates will suit me for “fast road” and occasional non serious track time.
 

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Discussion Starter · #958 ·
Oh, yes, you're actually right. Great mind you have Dominic. Never thought of this. If Q2 works then it would help in such situation a lot. It should make a perfect combo then because braking the spinning wheel would promote LSD action. Very, very Interesting.
 
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