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Author: Subject: Improving handling the locust way!
martinnitram

posted on 2/12/17 at 06:27 PM Reply With Quote
Improving handling the locust way!

Finally got my striker all back together after replacing the front end.
Gone from alloy race Leda uprights to escort RS2000 units, not straight forward as I'd hoped, in addition to the uprights I needed steering arms, modification to the uprights to make them fit, calliper adaptors m16 to wilwood, bigger bearing, bigger alloy hubs, new metro top ball joints, different lower ball joints, different steering rod ends, so a shed load of money spent - not exactly locost!

I was going to take the car and have it all set up but decided to have a go myself for free instead, and learn as I go, if I can't get it right then I will get someone to do it who can.
I'm no expert but have got a (very) basic knowledge of how car suspension works and a decent tape measure.

Previously the car drove like a pig, very stiff and darting left and right over the bumps needing two solid hands on the wheel and generally bouncing over the road rather than soaking it up so I knew it wanted a good looking at early on.

Viewing the car 3/4 from the front it had a lot of front neg camber and none at the rear, the back end just didn't sit right and appeared crab like.

After stringing it up with plumb bobs and spirit level, which took 3 attempts over 3 different nights to find the centre of the car, I found why it looked odd at the rear, toe in one side, out at the other and positive camber on both rear wheels, no wonder it was all over the road.
I wanted some geometry settings to get me started, so looked on the Internet, but it's mostly people's opinion and the figures vary wildly so I went with the following,

1mm toe in all round
1 degree negative camber front
3/4 degree negative camber rear,
120mm ride height front
130mm rear
Dampers set to full soft ( protech alloy coil Overs)
Tyres 16 psi all round

I have no basis for these settings other than it should now go straight
No idea what the spring rates are other than my 80kg makes the rear suspension drop about 1/2 inch on drivers side and it won't bottom out no matter how hard I bounce on it.

After driving it there is noticeable improvement, it will carry more speed on bumpy roads without me feeling terrified, track straight ahead and soak the bumps up better, but still some way to go, but it's really satisfying to put the work in and make an improvement, I don't doubt that I probably couldn't make it worse than it was, and as the car improves the gains will diminish, the car has the right components now to handle great.

So the next area I'm going to look at is the corner weights and the dampers then on to bump steer
Corners I'm going to attempt with bathroom scales, the dampers I'm not sure if they are damping equally or how to check this yet, but I'm open to suggestions on suspension tuning the locost way.
Feel free to comment.

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rusty nuts

posted on 2/12/17 at 07:27 PM Reply With Quote
One of the best " modifications" I've done on my car was a set up by Procomp , well worth the money . If it's any help I have a lever type corner weight gauge if your anywhere near Cambridge
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twybrow

posted on 2/12/17 at 08:49 PM Reply With Quote
quote:
Originally posted by rusty nuts
One of the best " modifications" I've done on my car was a set up by Procomp , well worth the money . If it's any help I have a lever type corner weight gauge if your anywhere near Cambridge


Ditto. My visit added at least 30% more cornering speed, and it just felt so much more planted. The best money I have ever spent on my car.

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ian locostzx9rc2

posted on 2/12/17 at 09:16 PM Reply With Quote
The settings you have used sound like the ones I used from Raw when I set my car up which was about right maybe increase the ride height on drivers rear by 5 to 10 mm if your going to drive it mainly on your own as said by other posts getting it set up by Procomp and getting shocks tested and damper rates matched will improve it even further .
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alfas

posted on 2/12/17 at 09:31 PM Reply With Quote
Procomp, even they are using Protech dampers are doing a complete different approach:

they claim that their revalved dampers do have reduced initial breakaway moment, hence they can use harder springs.
they say the original valves from protech, spax, gaz, avo are desinged for much heavier cars, hence they do not work in the correct window when such dampers are fitted to such lightweight cars.

the usual oldschool (sylva) x/flow live-axle striker has 130lbs springs all around...procomp recommends using 200lbs in front, rears remain soft with 130


-0.5 to -1.0 degree camber is usually more than enough on front, front tracking zero, maybe lsight toe-in is a good starting point.
for the rear i cannot help, as i think yours might be an IRS...where i have no expirience with

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SJ

posted on 3/12/17 at 10:43 AM Reply With Quote
Dialling out bump steer is easy enough. This made a huge difference to my car. In simple terms you need to make sure the car doesn't steer as the suspension moves up and down. To check this take the shock off, attach a laser pointer to the disc and see if it follows a vertical line on a wall or board placed at 90 degrees to the car.

It is then a question of putting spacers under the rack mounts until any movement is minimised.

Obviously this needs to be done on both sides and you may need several attempts to get both sides right.

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alfas

posted on 3/12/17 at 11:41 AM Reply With Quote
does the sylva / raw front tend to be suffering from bump-steer? dont think so
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Simon

posted on 3/12/17 at 11:44 AM Reply With Quote
I learnt about bumpsteer in a five minute lesson from Gerry Hawkridge. I told him what I was building and he said "Ron C is a ****" and then proceeded to tell me how to eliminate it. Then he shortened my sierra rack to my dimensions and it worked 🤣
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alfas

posted on 3/12/17 at 10:31 PM Reply With Quote
ok....locost and sylva is like lada and mercedes....
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peter030371

posted on 4/12/17 at 09:24 AM Reply With Quote
I asked RAW what they recommend for an IRS Striker and they gave me this info.

Front shocks should be 10 ½ inches ( 270mm ) closed, 12 ¾ (325mm) open.
Rear shocks should be 11 inches ( 280mm ) closed, 13 ¾ (350mm) open.
We normally set front ride height to 125mm from chassis under radiator to floor and 135-140 mm from chassis under seat back to floor with driver in car.
Shocks should have approx one–third bump and two-thirds droop.
Springs for road and light track use would be 200lb front and 180lb rear.
Set-up for independent chassis would be as follows;
Front
Camber 1 ½ - 1 ¾ deg neg
Castor 5 ½ deg
Toe 1mm out
Rear
Camber 0 - ¼ deg pos
Toe 2-4mm in

With help of Steve at Fury Sportscars (they are local to me) we got as close to the above as we could and it made the handling so much better. Like you before I did this I had plus 10mm toe out on one side at the rear and about 4mm on the other side!

Not checked yet but so far I can't feel any bump steer (unlike my previous Striker) after a few hundred miles of mixed track and road use

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martinnitram

posted on 9/12/17 at 02:16 PM Reply With Quote
quote:
Originally posted by peter030371
I asked RAW what they recommend for an IRS Striker and they gave me this info.

Front shocks should be 10 ½ inches ( 270mm ) closed, 12 ¾ (325mm) open.
Rear shocks should be 11 inches ( 280mm ) closed, 13 ¾ (350mm) open.
We normally set front ride height to 125mm from chassis under radiator to floor and 135-140 mm from chassis under seat back to floor with driver in car.
Shocks should have approx one–third bump and two-thirds droop.
Springs for road and light track use would be 200lb front and 180lb rear.
Set-up for independent chassis would be as follows;
Front
Camber 1 ½ - 1 ¾ deg neg
Castor 5 ½ deg
Toe 1mm out
Rear
Camber 0 - ¼ deg pos
Toe 2-4mm in

With help of Steve at Fury Sportscars (they are local to me) we got as close to the above as we could and it made the handling so much better. Like you before I did this I had plus 10mm toe out on one side at the rear and about 4mm on the other side!

Not checked yet but so far I can't feel any bump steer (unlike my previous Striker) after a few hundred miles of mixed track and road use


Many thanks, my settings are similar on front camber, caster and ride height, toe settings are a different set up to what ive gone for so far, but as mentioned I'm just 'sperimenting and have found some improvement doing so.

Looking at the Raw supplied settings I'm guessing mine was set to this some time ago and has been mucked up by previous owners, mine had positive camber on the rear although different each side, and a bit of toe out to add to the fun.

I'll come back to the settings you've described if I cant get any further forward improving my set up.

Not this week though, ice does nothing for the handling !!

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martinnitram

posted on 24/8/18 at 11:54 AM Reply With Quote
quote:
Originally posted by peter030371
I asked RAW what they recommend for an IRS Striker and they gave me this info.

Front shocks should be 10 ½ inches ( 270mm ) closed, 12 ¾ (325mm) open.
Rear shocks should be 11 inches ( 280mm ) closed, 13 ¾ (350mm) open.
We normally set front ride height to 125mm from chassis under radiator to floor and 135-140 mm from chassis under seat back to floor with driver in car.
Shocks should have approx one–third bump and two-thirds droop.
Springs for road and light track use would be 200lb front and 180lb rear.
Set-up for independent chassis would be as follows;
Front
Camber 1 ½ - 1 ¾ deg neg
Castor 5 ½ deg
Toe 1mm out
Rear
Camber 0 - ¼ deg pos
Toe 2-4mm in

With help of Steve at Fury Sportscars (they are local to me) we got as close to the above as we could and it made the handling so much better. Like you before I did this I had plus 10mm toe out on one side at the rear and about 4mm on the other side!

Not checked yet but so far I can't feel any bump steer (unlike my previous Striker) after a few hundred miles of mixed track and road use


Finally got the alignment done to the RAW spec and it's improved again, much more confidence inspiring so making progress.
I have previously checked for bump steer which was ok, shocks were rated at 180 all round as per RAW conversation.
Still not 100% happy with rough bumpy road handling as still a bit twitchy, don't think it's damping as it soaks bumps up ok so now looking at the front wheel of sets.
The scrub radius (I've asked about on here) I'm guessing is a bit much, the kingpin angle/ centre of tyre distance might be to much causing the kick I'm getting through the steering.

It's running 10mm wider hubs than standard and I'm looking to this next.
I can either change wheels to more offset ( expensive) or machine the hubs back ( cheap but don't want to weaken them) or machine a bit of wheel and hub.

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Angel Acevedo

posted on 24/8/18 at 03:20 PM Reply With Quote
quote:
Originally posted by peter030371
...
Shocks should have approx one–third bump and two-thirds droop.
Springs for road and light track use would be 200lb front and 180lb rear.
Set-up for independent chassis would be as follows;
Front
Camber 1 ½ - 1 ¾ deg neg
Castor 5 ½ deg
Toe 1mm out
Rear
Camber 0 - ¼ deg pos
Toe 2-4mm in
....



Could you elaborate?
Not native english speaker, so this confufses me.

I have 4" (104 mm) Shock travel and I am designing to have the shock collapsed one third and 2/3´s available for bump.
Maybe what you said but I´m getting it reversed....
Thanks in advance.
AA





Beware of what you wish.. for it may come true....

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steve m

posted on 24/8/18 at 06:11 PM Reply With Quote
The best single thing that sorted my "handling problems" was tyre pressure

Im now at 16/17 psi , but started at 32psi! even 22 was a vast improvement
but 176/17 is soooooooooooooooo muuuuuuuuuuuuuch better

steve





Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at




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Schrodinger

posted on 24/8/18 at 06:23 PM Reply With Quote
If you have concerns regarding your Protech shocks, give them a call, they are very helpfull. My shocks had been on the car for about 12 years without going on the road but one was leaking, they told me to send them back,which I did. The leaking shock had a scratch on the shaft which in turn damaged the seals, all of the shocks were tested and returned, for a charge of £30 iirc and all done within a week.





Keith

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martinnitram

posted on 26/8/18 at 06:50 PM Reply With Quote
quote:
Originally posted by steve m
The best single thing that sorted my "handling problems" was tyre pressure

Im now at 16/17 psi , but started at 32psi! even 22 was a vast improvement
but 176/17 is soooooooooooooooo muuuuuuuuuuuuuch better

steve

Hello Steve,

Been there and done the 32 psi tyres thing, now run 16 psi all round and grips very nicely.

So not a tyre pressure issue,
its not wheel alignment / castor etc as just had this all done and checked
its not springs, checked and correct
its not dampers, these 'feel' right

so just leaves the wheel offset / scrub radius,

could do with trying a different set of wheels with less positive offset to bring the wheels inboard 10mm or so and see if that helps.

Regards
Martin

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