Dan's 645Ci thread

[Ekona]

Essentially if you run toe out then when you turn the steering wheel, the front tyres are already pointing into the corner so you get much sharper turn in. In general it makes the car more unstable, rubbish for straight lines (it'll tramline like a bitch on the motorway) but ace for the twisties.

[roadtrip]

Interesting, I can see that wearing tyres quite quickly if you have a lot of small radius turns. You obviously feel it's worth it though. I know you like to get your tracking done frequently, do you change it for longer runs like going to Le Mans?

[Ekona]

Nah, the expense isn't worth it. Plus we always take the fun roads back from LM, so I wouldn't want to ruin those just to save a bit of tyre wear.

 

It's one of those personal things, some people would find my car horribly twitchy and nervous, but I'd probably find theirs an understeering blob It's all about balance really, I could go far more aggressive but then I'd chew through tyres in a couple thousand miles, and no way could I afford tyres that quickly.

[roadtrip]

It's surprising what you can do with what most people would assume were minor adjustments. Decent tyres along with a few suspension and geometry tweeks can transform even a heavy car like the 6 or Zed into something quite different for those who have a feel and desire for such things.

[andybp]

Nah, the expense isn't worth it. Plus we always take the fun roads back from LM, so I wouldn't want to ruin those just to save a bit of tyre wear.

 

It's one of those personal things, some people would find my car horribly twitchy and nervous, but I'd probably find theirs an understeering blob It's all about balance really, I could go far more aggressive but then I'd chew through tyres in a couple thousand miles, and no way could I afford tyres that quickly.

couldn't afford or wouldn't be allowed to ?

[Ekona]

Rumbled

[Ekona]

 

Centre Gravity visit complete. Man, what a day! I'll describe a typical day there, as well as my own experience. Long post, but hopefully it will explain just why I chose to go there.

 

Got there at 8:30am, nice and bright outside if a little freezing. Cup of tea and a quick catch up with Chris (owner) and Pete (his 2nd in command), then onto the nitty gritty.

 

First up, a quick 15min chat about the car. How I feel it handles now, how I want it to handle, anything I find odd about it, anything I particularly want it to do/not do. My aims are to eradicate understeer completely, without compromising the rear end emd stability I have and without reducing ground clearance. I explain the issues I have with nervousness on high speed corners, and how it never used to do that. Pete is looking after me today, and he carefully pays attention to what I say, makes a couple of sharp observations about what he thinks might be wrong then off we go for the first test drive.

 

This is a 20-25 min spin around Atherstone, taking in roundabouts to check for under/oversteer, DC to check for pulling left/right, b-road for general fast road testing, town centre with speed bumps to check for clonks, and cobblestones to check for high frequency vibrations. Turns out my car was pulling massively left and a little right, very unsettled rear on the B-road, and a random clonk over the speed bumps. No issues on the cobbles at all, barring a little tyre roar but that's the Michelins for you.

 

Back to the unit and up on ramps. Strap the Hunter HawkEye Elite kit on (an upgrade from the Beissbarth they used to use, 90secs to setup rather than 45mins!) for a quick geo check, and we can see the issues straight away. Or at least, issues from his POV. Not enough camber front, miles too much rear, a gazinga of toe out at the front and too much in at the back. Caster at least is fine!

 

Kit off, up in the air, and time to start checking components. Wheel bearings, bushes, ARBs, mounts, braces etc. Everything! They picked up quickly on a knock from the OSF (loose collar on the damper), and a big knock from the NSR (destroyed lower bush on the wheel carrier). The latter is a significant problem: If this isn't fixed, we cannot go any further. Quick call to ECP 3 miles round the corner, they have one in stock, 45 mins later it's here, and it's rapidly replaced. Luckily the old one came out okay, as otherwise it could've ruined the day. This is where the expertise of different cars really comes into play, Pete has this sorted quicker than I could have imagined.

 

Now the longer, more fussy tasks. We sort the ride height out first, to first off level everything out as mine was off by 9mm L-R at the front, then we raise the rear to give the car more rake which will aid in getting the nose tucked in. The fact I have a BGW and a small front splitter is also mentioned as causing issues, and that I need to install a bigger splitter at the front... Once the ride height is done, we set a very basic geo up, basically just to straighten all the wheels back to even with just a smidge of camber.

 

Corner weighting is a bit of a black art to some, as they think it means to add/remove weight from bits of the to make it all even, like putting the battery into the boot etc. Not even close: It's about adjusting the damper heights to ensure the footprint from FR to RL and vice versa is balanced and even. Imagine a table with two short legs opposite, and you balance it by putting beer mats under the dodgy legs to stop it rocking, and that's the principle here. My car is already pretty good, at a 49.2% balance. Good, but not good enough for CG, and Pete gets it to 49.9% by twisting the front shocks by just two or three turns. Tiny adjustment, big difference. Oh, and my car weighs 1642kg with a full tank, which I'm delighted with as that's less than OEM spec.

 

Corner weighting done, it's just the geo to sort. Pete knows what will work on my car for me from 7 years experience working with Chris, so he dials in the settings. I'll pop the sheet up in the next post, easier than explaining it here. It's a tricky thing to do properly, as changing the camber changes the toe and changing the toe changes the camber, so back and forth we go. Ride height also changes camber, which in turn changes toe, so that needs to be taken into account as well. Once it's done, we test all the components again, torque everything up, mark all alterations with pen on the components, and lower her back down. It's now gone 4pm, and we're still not done.

 

Second test drive. Pete takes us out again, and proves on the same route that the understeer is gone, the pulling gone, the clonk gone, the skittish rear end gone. I take reigns, and prepare myself. To say it's like night and day is doing them a disservice: It's absolutely transformed. Instantly I can feel the wheel not fighting me, and the front end feels at least 100kg lighter. Unsettling at first, but on the sweeping corners we're easy 10mph quicker than before. The car is flowing, its balanced, throttle inputs allow the rear to come round gently rather than snapping. In short, it's 99% perfect. The only snag is that it's not quite as snappy as I like it at the front, so Pete jumps out, adjusts the damping a few clicks, and we get back in and try again. 100% on the money. He seriously knows his stuff.

 

Back to the workshop a happy chappy, and it's the painful bit. £565 for the full day chassis tune, £36 for the bush (no on cost) and the labour to fit for free as we still achieved everything in one very long day. Is that a lot of money? Sure. Is it worth it? Completely. I've had the car fully checked over for everything, I've had repairs done on the fly, I've spent all day in the workshop with Pete bending his ear and increasing my knowledge, and I've ended up with a car that is significantly more enjoyable and faster than it was before. You couldn't get enough horsepower to make a difference for that price, and certainly nowhere near enough to gain you 10mph without even trying. It's incredible value, hell it'd be worth it even without the geo just for the health check and knowledge.

 

 

I appreciate it's not for everyone. Those that bimble around, use their fun car as a commuter car, or those who don't ever modify it or go near track: For those people, it's probably overkill. However, if you'd got adjustable dampers, or enjoy the twisty roads of Wales et al, ever track your car or who simply want to make sure that everything is working properly, this is the best Monet you'll ever spend. I had a full chassis tune done, but CG also offer a geo tune (so everything barring corner weighting, ride height and damper settings) for £325, which is getting on for bargain territory and worth doing for everyone. Pete loves the 350Zs too, so will be able to sort out just what you want.

[Ekona]

Before

 

 

After

 

[nowhereboy]

Awesome. Saw this on facebook earlier. Cars looking very well too

[KyleR]

That is probably the most symmetrical geo print out i've ever seen I need to find guys this good in my neck of the woods.

[gangzoom]

I thought about doing similar type of stuff before but I persume if your using is day in day out on our rubbish road, kerbs etc would cause all knock things out of alignment quite quickly??

[Ekona]

That is probably the most symmetrical geo print out i've ever seen I need to find guys this good in my neck of the woods.

Part of the reason they're so good is the tolerances they run to: Most ramps are set with up to 6deg away from level, CG run to 0.5deg. It just gives you absolute confidence in the end result.

[Ekona]

I thought about doing similar type of stuff before but I persume if your using is day in day out on our rubbish road, kerbs etc would cause all knock things out of alignment quite quickly??

Yes and no. If you were hitting potholes that were causing you to bottom out every single trip, or smashing into kerbs daily, then yeah you could knock it quickly. In regular use annually is fine, if you live in an area with seriously crap roads then maybe every six months. If you have a place you trust near you, you could a day at CG then take the settings to your local place to redo them. You'd miss out on all the integrity checks, but at least the geo would be close enough.

[davey_83]

This place is epic, in the day for rowdy track spec Almera GTi the did a full custom rear axle bend to dial out the OE toe in most FWD cars have WOW

[gsexr]

Always an interesting read

[StevoD]

sound like i need to get the Z over to them

[nissanman312]

Just up the road from me Awsome I'll have to pay them a visit

[grahamc]

Hmmmm, tempted to see what they can get out of the GTR, yours sounds to be an awesome result

 

Though I am on the standard suspension (from a 2012 car).

[Flex]

Winning on the next level. Boss.

[Ekona]

Hmmmm, tempted to see what they can get out of the GTR, yours sounds to be an awesome result

 

Though I am on the standard suspension (from a 2012 car).

Is it height adjustable?

 

Even on non-adjustable suspension, they'll work wonders. They transformed my 911 from generic understeer sportscar into nimble rear-biased throttle-steerable hero.

[grahamc]

Hmmmm, tempted to see what they can get out of the GTR, yours sounds to be an awesome result

 

Though I am on the standard suspension (from a 2012 car).

Is it height adjustable?

 

Even on non-adjustable suspension, they'll work wonders. They transformed my 911 from generic understeer sportscar into nimble rear-biased throttle-steerable hero.

 

Honestly dont know..... dampening can be adjusted, but not sure about height. Good to know then, thanks

[Ekona]

Nearly two years exactly after her first track day, I final got a chance to take the Bummer back out and this is the first time she's been tracked since I started the upgrade program. Snetterton 300 was the destination, never been there before either so a baptism of fire all round

 

 

Nice and dry all day, temps in double figures, couldn't really ask for better conditions. The track layout is reasonably easy to learn and get to grips with, and there aren't any really odd corners that need you to take a bizarre line or anything like that. As long as you remember that every single corner here is a very late apex, you can't go wrong.

 

So how was the car? Both superb and useless, in equal measures I spent the first couple of sessions with the dampers in road settings to get used to the track, however these proved to be way too soft still so I bumped them up by a further 5 clicks all round (now sitting at 5 from stiff at the front and 10 from stiff at the rear). This transformed the handling, and meant I had far more confidence to really lean on the car. At 1642kg full it's not really something you can throw in, and I had to massively adjust my driving style to suit as it simply won't pivot very quickly on the apex. It means you can't really chuck the car in as I usually do on track, and you must maintain a very smooth driving style to keep the balance and pace up. Actually very rewarding when you get it right, and start a nice flow going.

 

I also tried a little experiment...

 

 

To wing or not to wing, that is the question? Center Gravity suggested that where I located the wing along with the angle of it meant that it might actually be doing something useful after all, so I removed it and tried some hideously unscientific tests. On the Bentley Straight I was losing about 10mph by the braking point due to drag (not really surprising), however it was the corners that fascinated me. Low speed stuff was irrelevant, but the higher speed corners like Riches and Coram were very noticeable: With wing off, turn in was sharper however I was unable to get the power down quite so quickly without unsettling the rear. Wing back on and I got the opposite, turn in was blunted but the grip under power was improved. I mean we're talking fractions here really, and tbh either setting didn't make such a difference that I'd prefer it, so the wing stays on purely for looks.

 

The biggest issue I had were the brakes. I'm on OEM all round, great on the road but one hard lap and they're toast. Grumbly, fading, squealing, just not good. Coming into Brundle (fnar) I ended up lifting and doing two applications, just to get the car to slow down enough. I'm already looking at discs and pads (looks like I share a brake pad size with the E92 M3 so CL RC5+ should be available, and a disc with the E92 335i so options there too) as going for a full BBK setup is north of £3K, and tbh I don't and won't track the car that much to make it worth while.

 

 

Comparing the car to others on the, I was noticeably faster through Hamilton than pretty much everything else barring the Caterhams, and I'd not sure why. I caught a 997.2 GT3 through there and into Oggies at a rapid rate of knots every lap, but he'd then murder me under braking and bugger off. I managed to blag a few pax rides with a race-spec EP3 and a Mountune FRS mk3, and my entry speeds were almost identical to theirs so I was pleased in that respect as both drivers were seriously capable of piloting their machines. We were all on road tyres too (me on MPSS, EP3 on ContiSC5, and the FRS on Neovas) so nothing to distinguish there. This is the first time I've properly tracked the MPSS, and given they're half dead already I was cautious with my use of them as I didn't want to kill them sliding round the hairpins all day. Which, btw, is hilariously easy to do in something as big as the Bummer. No need to fear though, they were absolutely wonderful. Plenty of dry grip, nowhere near as squealing as the Contis, and they wore perfectly evenly all over which shows what a great job CG did on the alignment for me. I still want a set of semi slicks for the car, but no-one should fear tracking on MPSS at all. The Contis I wouldn't use, as the Civic owner had to stop by 3pm as they'd started to disintegrate with chunks coming off the outer shoulder...! Not good.

 

 

All in all, it was a brilliant day and in a brilliant car only hampered by typical BMW brakes. Everything else though came together perfectly, from the suspension settings to the seat being proper comfy AND supportive enough for track use, and being able to finally use the power the car has. Time to book the next one up now, methinks

Edited March 12, 2017 by Ekona

[Keyser]

Good write up Dan

 

I may try setting up my rear spoiler using a similar (not so) scientific approach

[brillomaster]

like the write up! i like snetterton, nothing too complicated but satisfying to get right. also its a good track to play with the balance of the car, since there is a good mixture of steady state corners to reallty nail down what the car is doing, without worrying about stuff like gradient and camber. How did you find the corner at the end of the bentley straight and then the tight left at the end of coram? i always found that tricky to get the car stopped and change direction without unsticking the rear.

 

are you running 18s? get some federal RSRs... 245 front, 255 rear. i think even from MPSS you'll notice a difference. and in terms of longevity, the rears have done about a dozen trackdays now and still have 3mm tread. (fronts got killed early due to a lack of camber and too much body roll on the new car before the suspension was sorted)

 

Actually, tell you what... get yourself along to Bedford GT on 14th April, then you can try my 328i on decent tyres. And feel what decent brakes feel like, getting along nicely with EBC Bluestuffs, the fronts have done 4 trackdays now and still have pad left.

Edited March 12, 2017 by brillomaster

[Ekona]

The flick after Brundle was fine, no issues with a loose rear there at all: In fact I was amazed at just how well the car changed direction at that point. Coming onto the pit straight was much more awkward though, without decent brakes it meant I was never really able to carry enough speed through Coram to really get the car on it.

 

Yup, on 18s, and will be grabbing something stickier soon. Probably going to stick with either Toyos or Michelin, although it's a bugger trying to find a 275 rear.

 

Will have a look and see if we're busy on the 17th, may well take you up on that