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ActionDan

Car too firm/skittish/struggling for grip.

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Diff might get a shim up when I remove the subframe to change the mounts. I also see replacing bushes/arms etc as mainteannce on a 89 model car that still has plenty of stock things in it, it's not a bad move at all in my eyes and if I have the time and the money I think people need to focus less on how I am spending those and just give their input on the actual question I'm asking.

 

No point tracking the car if it's chewing up tyres. I could simply undo the changes I made (swaybars) and keep driving and never go any faster or I can fix what's wrong with the setup, keep driving at the same time and improve car and driver together.

 

Honestly, my driving is far from aggressive, it looks that way because I'm trying to extract as much as I can from the car, that means getting close to lose of grip, which means the car is squirming around all over the place and I'm trying to save it, it's squirming around because it's unbalanced. So I can either drive slower and not have it squirm around or fix the balance issue...

 

At some point I'll say "that's as good as the car will get, the only improvement in lap time will be me/conditions/small variables, but today is no that day. Still plenty of room for improvement in the car (and me). No point trying to learn to be consistent in a car that has obvious issues, unless your idea of fun is just drive slower so those issues aren't a problem.

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Why are you destroying tyres? Did you think its to do with sway bars? Maybe it's to do with your alignment.... If your after a good alignment Keith for wheels at underwood has the latest in alignment tech which has always been spot on compared to those old school setups. I think that would be a wise thing to do after you set your bump and droop to Mca specs. It looks like on the wheel that you measured you have 26mm of droop. Another 10mm wouldn't hurt. Go into the Mca blog section to confirm the correct bump and droop. It wouldn't load for me for some reason. My understanding is your bump and droop is near even in the front 40/40 mm and the rear has alittle more bump travel to allow for soaking bumps under power so 50/30 or 45/35 mm. This is based on an 80mm shock length.

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It started blue'ing the outside edge of all 4 tyres very noticeably at the last track day, after installing swaybars. Was fine on tyres prior to that, alignment didn't change with swaybar install, only geometry.

 

IMG_20150425_160443.jpg

 

So I can either remove those bars or continuing developing the suspension to fix the balance issue.

 

Everyone said the car was too low (without RCAs) and needed castor, so I'm starting there.

 

How'd you work out the 26mm of droop if you don't know the shock length or travel specs? I'm still new to bump/droop setup. I have on shock out to play with it, can see the height was done with base height adjuster and not spring perch.

 

Would there be any reason to set to MCA specs if I'm using different shocks/diff valving and diff spring rates?

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Putting sway bars in has only exaggerated an issue. Castor in the front won't cause or fix that. I think your string alignment may need to be addressed but for now as mentioned put stock bars in or get the white line pair. On all cars I've setup shock length ranges from 75/90mm from Hondas to gtrs. The standard bump and droop settings are listed for fwd/rwd/4wd vehicles in there blog section. It has nothing to do with brand or dampener settings. You should read up on this in Mca blog section and also you can learn a lot from the faq section. To explain how I got it on the forum will take a while but simply your resting hub to guard is 345 and your lifted measurement which shows droop was 369. 369-345 is 24mm. So you need to turn you spring lock rings up to compress the spring roughly 10mm drop the car check hub to guard and then droop again. Once your droop is set turn the bottom of the coil over down to set height. If your shock length is 80mm and you have 35mm droop you have 45mm of bump.

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Also to clear it up if you're adjusted from the bottom bc cool overs don't come set to the weight of your vehicle which Mca do which is another trait that makes them a better solution for people that want to throw them in and drive.

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I'm looking for a Whiteline rear bar, but a 22m solid bar will be firmer, even on soft, than 25mm hollow (which equates to roughly 19mm solid if I recall) so that's only going to make it firmer in the rear.

 

As I mentioned before, the car was not using tyres like this on the same alignment until the bars went in. I can't put the stock bars back in as I'm selling off all the old stock suspension.

 

How do you know my hub to guard is 345? That sounds right/close but I don't know if I actually ever mentioned that in my build thread?

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Gee mate, that's what you told me in a previous post. Get the pair of white line bars. Your making assumptions on hollow/solid ect. White line make a pair to suit your vehicle. I'm pretty sure they know what there doing. Having the adjustment is super helpful once your rake is set on your vehicle. As mentioned your stiffer bars have exaggerated an issue. Set bump droop/ then set rake with 5mm lower in rear. Install a set of minimum size white line adjustable bars on soft. Get your alignment from Keith 4wheels if ta in brissi or ring around to get a repeatable place with the suggested specs. Drive and adjust rear bar to counter under steer or front to adjust oversteer. Keep bars as soft as possible with high spring rates. Also keep us dampeners in the middle. Once you have a good balance after adjusting bars then adjust with clickers for the final adjustment. This will net you a great result from spending minimal money. It will be night and day difference. Good luck with your track stuff.

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Also at a hub to guard around 345 will have good geometry for your arms. It may look a touch low but it'll work well. Once you have it any lower you introduce a lot of probs and much higher the car will float alittl if you have elevation change like at lakeside.

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Ahh yes I did say that sorry, re the 345.

 

Can you copy/paste the MCA blog entry I cant get to it for some reason.

 

I'm not up that way so I'll have to use someone local. One of my clients is the local BMW and they apparently have a trick new aligner he'll let me use for mates rates. But I was also looking at these - http://www.tenhulzen...kage%C2%A0.html

 

The only bar Whiteline make for s13 now is 22mm adjustable. They had a 20mm also but it's a deleted item.

 

Easier than towing the car back and forth as I have to borrow a trailer.

 

I remember reading that around 345 was not bad for geometry but the LCAs are below parallel and everyone said that was bad, so the RCA's in the front should get that almost back to level.

Edited by ActionDan

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I think you should contact white line but regardless of that you will be able to neutralise the car buy adjusting the front if required. There's also many other ways to skin the cat. I wouldn't do your own alignments yet and focus on driving and understanding your car. The artical as massive. Contact Mca if u want to view it.

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I got told many things about geometry. If u talk to mca they will laugh at you and tell you to worry about everything else first. It doesn't play a huge part like getting you bump and droop set and unless you understand what it's doing and what you want it to do by driving it you won't know any better. I found I got less to know bump steer when my arms were a touch low. 10mm high and I had bump steer everywhere. You just need to get out and drive then address the issues like you are doing. But arm geometry is one of the last things to worry about. It's not like your running crazy aero and need to be 60mm of the ground. Just lift it 5-10mm all around if us sorry worried about arms on an angle.

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Already have the RCA's, needed new ball joints and LCA bushes anyway, now I have both.

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Let's talk diffs, it's obvious the stock one is tired.

 

Options? Shim it to freshen it and tighten it?

 

Change centres to get better ratios?

 

Complete new centre?

 

I'm thinking a shim and a different centre with more ideal ratio is the best middle ground.

 

I have no idea what's in the car, ratio 5-6bolt axles etc.what ratio to go for and what they come from etc.

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Talking to the fast Queensland guys, they use the stock diff shimmed. 2way is no good for circuit and most 1.5ways are alittle too aggressive. I had my Cusco1.5 way made slightly less aggressive. Was good but so is the stock s15 diff for track. If you can do an s15 diff I'll gove you my helical one. Just pay shipping, only problem is it'll be gear for a 6speed. Great track diff though.

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Apparently there's a bit of dicking around to make that work, but I appreciate the offer,

 

Thanks Pmod, maybe just shimming it is the best/easiest option without stuff around swapping things all over the place.

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Also thought on solid vs poly diff bushes as I will replace those at the same time.

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I thought it is a bit of a stuff around but it works a treat. Wish I kept mine over my cusco diff.

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Oh and S13 diff is already solid mount I see so disregard that...

 

Diff shim amounts though?

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The Nismo centers with adjustable settings are the bomb. The GT Pro, the old GT Pro TT and the GT Pro Carbon which replaced it all have three different torque settings for locking up.

 

Almost everyone in our club uses a 1.5 way Nismo center for track work.

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Can the helical be fitted with a ring gear from a viscious LSD?

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yes, dumhed did it in his hello kitty race car. 4.363 helical in the end. His diff was opening up when he was lifting the inside rear wheel on highspeed corners, fixed by running a ridiculous GT wing.

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I don't know enough about diff internals to know if what you're saying means it's easy or not...

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Helical diffs open up when u lift a wheel, but when there on the ground it's an unreal diff. Running stock sway bars would probobly work better with a helical diff

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wouldnt a Viscous diff also open when tri-podding?

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Above. Unless the tracks has cornered crests you will never have a problem with a well setup car

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