Sam's build thread

[sambb]

The hillclimb site report just went up. No mention of us road reg cars I guess because the formula libre guys were doing some pretty amazing things. Malcom Oastler in the yellow OMS is the man. He was the head race engineer at Jaguar F1 when Mark Weber was there and also worked for Williams and Mclaren I think so he knows a thing or two about prepping an open wheeler. His car is an E85 non intercooled turbo Hayabusa making 350hp and the whole car weighs on 305kg.

http://hillclimbnsw.com/report-2017-...d-hillclimb-2/

and here's my humble non open wheeler going around the bottom hairpin before the run up the hill. My net connection is stuffing up and I can't seem to upload so I'll get a vid up as soon as I can.

[sambb]

beam painted.out with the old.in with the new.on the scales. Naked beam without discs or calipers is 27kg.

[sambb]

The standard beam + whiteline 20mm RARB came in at 30kg = 3 kg heavier than the boxed beam. With the 4kg per wheel and 3kg saving there, my rear end is articulating 11kg less unsprung weight than a standard street car with a bar. Actually I think the beam weight saving has to be halved when working that out as its attached on one side to the chassis, but either way its a good saving.
I can definitely see the value of the UR cross brace. These flanges will be warping all over the place now the bushes have next to no give.
possibly my worst fears realised. The problem with solid bushing an angled bush housing is that the beam can bind. I went for these Polybush 44AX bushes because they appeared to have decent sized voids. When I got them the voids weren't as deep as I'd hoped and the centre steel sleeve is a much bigger diameter than the narrower pin in a Powerflex. Well they do appear to bind. The beam is happy hanging anywhere from 360-405mm (arch to hub centre) but below or above that the beam tightens up noticeably. My running height is a fair bit further up from that so I'll jack it up into that area tomorrow and get a gauge on how tight its getting and also on how stiff the beam is. The beam is WAY stiffer than stock without a bar and looks to be stiffer than with the bar. There wasn't much visible droop from one side to the other at all so I think the first drive is going to have to happen with the front bar on hard to square things up!
sorry a sideways pic. Just showing what the boxed part of the beam looks like that faces the fuel tank. Looks neat as and doesn't foul on anything.

edit: after another look the beam is unbound between 330-410mm. Above and beyond that you can feel it bind. eg rather than having to jack the beam to get it into a position to get the springs in and put the bolt through the damper I actually had to be doing the opposite -pulling down hard on the beam to do that.

[HaydEn]

That's a huge weight saving.

I was thinking the plate would weigh alot more. Whiteline must be a solid bar?

Sent from my Moto C using Tapatalk

[sambb]

Yeah I was relieved when it came in 3kg lighter and will be stiffer. Yep the whiteline bar is solid. On track when I run the enkeis (-4kg each corner) , new rear beam (-3kg assuming I won't need the RARB anymore), de muffler (-5kg) and rear seats out (- 20kg) and 10L of fuel at the most, the car is minimum 36kg lighter in the back end.
Its tempting to relocate the battery to the boot because of that but I still think I'd prefer to keep the HC20 I'm getting in the engine bay along with the 1L water coolant reservoir I'll be using for the water injection, because the light corner of the car is the left front and I don't want to make that worse. So because the rear is so light and stiff I'll hold off on fitting the Eibach toe/camber correction until I can get a gauge on what its like - because it'll have so much rear roll stiffness I think the oem amount of rear toe in might be a good idea to keep it well mannered.
MCA just contacted me and their new X series coilovers with a few revisions are ready. We're going to go front: 8kg/mm(445lb/in) and rear: 6kg/mm(335lb/in). Initially we'd talked about 9kg:8kg but I'm happier to go 1 step softer on the front as I may be able to retain the whiteline FARB and have some adjustability and it'll suit the hillcimbs better I think. The softer rears will work better with the stiffer beam and keep the ride tolerable. Its going to be a sled that's for sure. Just hoping I can get them delivered before my wife gets back from NYC cos I'm a dead man if that delivery gets spotted!

To other MCA owners, does the crown that shrouds the top of the strut tower need to be cut off for fit up so you can get access to the damper adjustment?

[sambb]

Props to Whiteline for helping me out. My whiteline adjustable droplinks haven't been in this car really since the rebuild. Where the top ball joints bolted onto the strut tower on my B8's they sat just a tad too close to the bracket. In normal driving this wouldn't be a drama but getting in and out of my driveway where the car onto two wheels sometimes I think it pulled some funny angles and caused some little tears in the boots. I called thrm to see if there was a boot kit or if they could be bought separately and they sent a new pair of the ball joints out to me for free which is pretty good service.

Another question that I need help with. Can anyone with a standard front end/standard front bar and droplinks please tell me what the distance is between the driveshaft and the underside of the anti roll bar where it sits directly above it.? Now that the car is lowered a tad I want to set the adjustable droplinks so that this gap is the same because I'm not sure that the FARB mount on the MCA struts will be in exactly the same spot as on the OEM's. thanks

[Sydneykid]

The problem with solid bushing an angled bush housing is that the beam can bind. I went for these Polybush 44AX bushes because they appeared to have decent sized voids. When I got them the voids weren't as deep as I'd hoped and the centre steel sleeve is a much bigger diameter than the narrower pin in a Powerflex. Well they do appear to bind. The beam is happy hanging anywhere from 360-405mm (arch to hub centre) but below or above that the beam tightens up noticeably. My running height is a fair bit further up from that so I'll jack it up into that area tomorrow and get a gauge on how tight its getting and also on how stiff the beam is.

It should help the travel if you jack the beam up to the desired ride height before tightening the bolts for the bushes.

Cheers
Gary

[sambb]

Thanks mate. Yeah I did. I had the beam in there level with the ground (the old bushes would have allowed it to sag right down) when I torqued it up. I had another look at it today and it seems that it may have ok movement around where I want the rear ride height set up. Things will be different when the calipers, discs and wheels are on but I think it'll be less inclined to droop the inside rear a long way through corners due to the extra roll stiffness but also the stiction that the bushes has introduced.

[Sydneykid]

Thanks mate. Yeah I did. I had the beam in there level with the ground (the old bushes would have allowed it to sag right down) when I torqued it up. I had another look at it today and it seems that it may have ok movement around where I want the rear ride height set up. Things will be different when the calipers, discs and wheels are on but I think it'll be less inclined to droop the inside rear a long way through corners due to the extra roll stiffness but also the stiction that the bushes has introduced.

I haven't played with this model specifically but in general polyurethane bushes with well lubricated crush tubes should have next to zero friction and/or rotational resistance. There will of course be increase resistance to distortion due to the higher duro of the polyurethane (when compared to rubber). To offset that, the crush tube in a rubber bush has to be bonded to the rubber, so it does have noticeable resistance to rotation. Voids in the rubber do help to minimise it but it won't get down anywhere near zero like a properly lubricated crush tube in a poly bush.

If you are concerned with excessive inside wheel droop the rear antiroll should be sufficient to prevent that. The alternative is droop limiters in the shock absorbers.

Cheers
Gary

[sambb]

They should be ok. The main problem comes from the angled bush casings. In top view they are probably at 45 degrees to each other and in front view the casings angle upwards toward the rear seat bases slightly too. The crush tubes will allow up down articulation ok within a given range but then the angle of the bushes starts to force the bush to distort and then the poly, even just for up/down movement starts to lock up. Laterally I think they'll be unreal with no more of that detached rear end sog like before.
Yeah I had read a bit about droop limiters, everything literally from cables to internal damper ones, but figured I'd just go for more roll resistance from the twist beam than from the springs. Apparently limiters can be a bit abrupt in the way they limit droop (only read it have no experience) but if the bushes act to limit droop which I think they will (car is still on jacks with the beam just hanging there level with the ground) then hopefully its nice and progressive.
I just got the rear calipers back and don't know whether to slap it all together and go for a drive or leave it all in pieces and just wait for the coilovers to arrive. I think I'd rather drive it now so that I have a good before and after reference for what the beam is doing rahther than change everything at once but that means garage time tonight and I'm sick as. I'll see how I go.