74 replies to this topic

[bladerunner1000]

Evening all, being quite new to the forum i feel the need to introduce myself before asking for help.  Two years ago i brought my first High Mileage VXT, i soon decided that it needed to be modified so i opted to buy a car with lower miles.  Last April i brought my Red CS Stage 2 VXT from Dan Robinson, since then the car has undergone the following modifications:

 

• Nitron Coilovers
• TD 1.2's 17/16 combo
• TMS rear CF diffuser
• Robin Front Splitter (recently fitted after respray)
• Fog light brake cooling mod in progress
• MMG rear wing (not yet fitted, wing struts are currently being welded by Pro Alloy)
• JK Composite Seat with modified drivers sub frame
• Custom Harness bar
• Apexi Air Filter
• Pro Alloy Hard Intake Pipe
• Pro Alloy Gear Box Breather
• Pro Alloy Radiator
• Pro Alloy Charge cooler
• Courtenay Sport Enlarged Plenum with Pipework
• VXR Turbo (not yet fitted)
• VXR MAF (not yet fitted)
• VXR Injectors (not yet fitted)
• Front Clam Respray (this is yet to be mopped and now the rest of the cars paint needs restoring)

 

I will be purchasing a Courtenay Sport Uprated Clutch next month and then its time for CS stage 4. 

 

HOWEVER, i am having issues with my Robin splitter, it was fitted last week and i love the way it looks.  The problem is occurring at high speeds, when the car gets over 100 mph the rear end begins to lift and the splitter is catching the road!  I know plenty of members have these splitters fitted with no issues which points the blame at how i have installed it.  My heights are currently 95/120, (i am yet to have my suspension set up so please hold the abuse).  I still struggle to believe this is the fault.  I have fixed the splitter using 5 M8 bolts with penny washers using the guide on the forum with the bolts being located 145mm from the front face.  Is this wrong??  I would like to get this issue sorted before having the splitter repaired. Below are pics of the car and damage.  Cheers in advance, J.

 

[CocoPops]

95mm is very low for the road.

[-Dab-of-Oppo-]

I see no pics below of the car and damage?

[techieboy]

25mm of rake is not going to be helping. 5-10mm is the usual.

[bladerunner1000]

Apologies, i did try copy and pasting them into my post by no joy .  I hope this works.

 

 20140315_174745.jpg   44.89KB   28 downloads

[Mike (Cliffie)]

Your rake is the issue here and no wonder you are having rear end lift.

 

Set your car up first and you will find your downforce issue is solved.

[Bumblebee]

Where abouts have you took the ride height measurements from? Reason I ask is it doesn't look as low as you mentioned in the pics

[Nev]

Sounds quite unusual to me, I would not have expected the rake to affect it so dramatically, but it's the only thing I can think of.

Edited by Nev, 16 March 2014 - 08:07 PM.

[bladerunner1000]

Any recommendations on height with Robins splitter would be helpful.  The height measurements are from the bottom of the splitter and the rear belly pan of the car.  I would usually have waited for the height to be set up but the nice weather was too tempting,  needless to say i soon regretted that after destroying my splitter.  Lesson learned.  Rapidly discovering modifying a VX is nothing like modding anything i have owned previously.

[GeorgeBC]

Anything below 120 is seen as pointless in a vx. Surprised you can get over a speed bump with it at that height on the road. Is the splitter all about looks or function? I've had a robin splitter and got rid recently because of look reasons and the fact i can't tell fcuk all difference with it on.

[Nev]

Any recommendations on height with Robins splitter would be helpful.  The height measurements are from the bottom of the splitter and the rear belly pan of the car.  I would usually have waited for the height to be set up but the nice weather was too tempting,  needless to say i soon regretted that after destroying my splitter.  Lesson learned.  Rapidly discovering modifying a VX is nothing like modding anything i have owned previously.

Ride height is measured from under the front most part of chassis and the rearmost part of the chassis (there are diagrams on here somewhere if you search). Thus your measurements from the base of the splitter are understandably confusing people; try getting under your car and re-measure from the usual datum points and let us know the new measurements. As Aimy spotted, your car doesn't look like it is running at 95mm front.

Edited by Nev, 16 March 2014 - 08:22 PM.

[Bumblebee]

The Robin splitter is quite a big splitter so (imo) I wouldn't want to run any lower that 120mm (Measuring where Nev has said) although I'm Running 115mm on the front but my splitter doesn't stuck out quite as far as yours

Edited by Bumblebee, 16 March 2014 - 09:11 PM.

[bladerunner1000]

I have now read the thread on ride height measurements and the heights are 105 / 125.  Now i am really confused as to why the splitter is turning into a road sweep at speeds of over 100 mph. Perhaps my mounting points are too far back?? An RSV4 is certainly looking appealing at the moment.

 

[GeorgeBC]

When i didn't attach my splitter well enough you could here it flapping at very high speeds. When Cliffie gave his a wallop in off road excursions it cracked the top mounts of the clam so i find it hard to believe its giving you have so much downforce its dropping the clam dramatically to scrape along the road.

[techieboy]

Sort your ride heights and rake properly and pull your finger out and fit your big gay wing, to even things out.

[bladerunner1000]

Ha ha ha, i did think that my wing would possibly even it out.  Could anyone with a Robin splitter fitted measure the distance between the splitter front and the fixing please?  If i could upload the image of the splitter in its current state there would be no doubt that it is dragging along the road.  I have seen that some people use  toe joints but surely that is not necessary?

[jonnyboy]

The issue here is the overall ride height not the robin splitter. I run 115 front on my Elise and this is enough to cover speed bumps but nothing else. If I stuck a splitter on it that would probably scapre a bit.

 

As Mentioned get your rake down to 5-10mm difference for starters. 

[danger7]

Hi all,

 

Down force with a VX its not going to happen no matter how many appendages you bolt on, maybe a kilo here or there of df but not significant to make a massive difference to the car's handling unless someone can flame me down with data. Could be asking for it but i'm a naysayer.

 

Cheers

Ian

[jonnyboy]

You can get meaningful downforce but it needs to be balanced. If you are ever going to be able to drive it quick enough to get the benefit is another matter

[VIX]

Ride height is measured from under the front most part of chassis and the rearmost part of the chassis

Illustrated here: http://wiki.seloc.or...ing_Ride_Height