New engine + ARB requires softer front springs, suggestons??

[se7ensport]

Looking for front spring weight recommendation, I've just changed to a Duratec from a Pinto and dropped about 60kg of weight in total: denso alternator, alloy bell housing, 3.7kg fly wheel etc... (the Duratec weights in 20kgs less than a Zetec), in addition I have also added a front ARB, unsurprisingly the existing front 240lb springs feel overly stiff and skittish on potholed wet roads.

What front rates are you guys with lighter engines using?

For completeness I'm using 180lbx8 springs on 12in shocks rear and 240lbx7 springs on 11in shocks front, camber is 1-1.5degrees with slight toe in and front shocks now have rebound wound off completely and I struggle to bounce the front end by pushing on the front wing, the rear moves nicely and has about 6 clicks of rebound, GAZ shocks all round, matched pairs with 500miles on them..

Thanks
Alex

[stylussprinter]

Seeing as the front wings are fibre glass I'm not surprised it wont bounce or you'd break the wing , unless of course your shocks aren't in good nick OR there's no travel other than the bumpstop . I've set bike engined Sylva's up using 225lbs front with that same ARB so before moving to less lbs up front check those shocks and piston travel left , visable between the spring coils when the car's on the ground.
When you say rebound , I am assuming you really mean '' bump '' because unless you've bought DA shocks there's no seperate control of rebound . If your shocks are in good condition then NO clicks at all will result in the car bouncing up/down if you go over pot holes etc because springs will bounce unless the speed of bounce is controlled by the shocks. You need a minimum of 1/4 total clicks as on my notes(1/3rd max) then 1/2 on the rear(2/3rds max) Have you set rake at 20 to 25mm
I suspect there's something else going on here not connected to spring weights. Tyre pressures

[se7ensport]

Hi Rob

Glad to have your thoughts on this.

It hasn't ever felt great at speed on uneven roads; it's always been twitchy on anything other than smooth, give it a flat roads and it sticks really well.

With the Pinto in the car the front could be pushed down by sensible pressure on the wings, it hardly moves with the new engine (there is 60kg less force on the shocks so it must have an effect), I compare this to the rear of the car that shifts with ease. There is a bit of squeaking coming from the front that I hadn't noticed before so I will pull apart, clean and re-grease as it's a quick job.

There is close to 1.75 inches travel before the bump stops come in to play, the shocks are also in great condition. You are correct, I did mean bump, I was running 3 clicks previously, but wound these off to experiment with chassis movement.

Regarding ARB, it pivots smoothly but must be adding a bit more resistance to the suspension, if I push on the rockers the chassis moves with ease and resettles, the car is noticeably flatter through corners; having a front ARB should require lower spring rates though, or so my understanding suggests.

Tyre pressure is normally set to 18psi rear (Toyo R888) and 19.5 front (Toyo T1R), I've just rechecked to see if that has changed since setting about 2-3 weeks ago: n/s/r 15.5, o/s/r 17, n/s/f 19.1 and o/s/f 18.9. I'm not surprised by the drop off on the rears as it spent 2+ hours on the rollers.

Wedge is set at 23mm, is the point of wedge that once driver weight (and passenger depending on setup) is added to the car that the floor is then sat parallel to the ground?

Out of curiosity what rear springs were you using with the bike engined car?

[stylussprinter]

Hi Rob

Glad to have your thoughts on this.

It hasn't ever felt great at speed on uneven roads; it's always been twitchy on anything other than smooth, give it a flat roads and it sticks really well.

With the Pinto in the car the front could be pushed down by sensible pressure on the wings, it hardly moves with the new engine (there is 60kg less force on the shocks so it must have an effect), I compare this to the rear of the car that shifts with ease. There is a bit of squeaking coming from the front that I hadn't noticed before so I will pull apart, clean and re-grease as it's a quick job.

There is close to 1.75 inches travel before the bump stops come in to play, the shocks are also in great condition. You are correct, I did mean bump, I was running 3 clicks previously, but wound these off to experiment with chassis movement.

Regarding ARB, it pivots smoothly but must be adding a bit more resistance to the suspension, if I push on the rockers the chassis moves with ease and resettles, the car is noticeably flatter through corners; having a front ARB should require lower spring rates though, or so my understanding suggests.

Tyre pressure is normally set to 18psi rear (Toyo R888) and 19.5 front (Toyo T1R), I've just rechecked to see if that has changed since setting about 2-3 weeks ago: n/s/r 15.5, o/s/r 17, n/s/f 19.1 and o/s/f 18.9. I'm not surprised by the drop off on the rears as it spent 2+ hours on the rollers.

This is VERY important ---- don't run odd tyres front to rear , the walls will react in a totally different manner as will grip . Secondly there's no way you can assess a car with uneven pressures. Even worse that the road tyres should be up front BUT if you're going to run R888's they must be all round and at the same pressure = 17psi . I've spent ££££'s testing to arrive at that pressure. I wouldn't even get in the car unless I'd set pressures.

Wedge is set at 23mm, is the point of wedge that once driver weight (and passenger depending on setup) is added to the car that the floor is then sat parallel to the ground?

WEDGE = measured with no persons in the car. If then an 80/85kgs driver sits in the wedge should be between 5 and 12 mm's. It's there to adjust oversteer/understeer provided my other parameters are in place.A level car will understeer badly.

Out of curiosity what rear springs were you using with the bike engined car?

Rears on that car were 180lbs and the driver was 10st or 63.5kgs

[hearbear]

Hi Alec

sorry to jump in on a slightly different subject have you got to the bottom of the ECU problem, read on the locost forum and must have been a real pisser when that happened.

George

[se7ensport]

George, ECU is with the importer today, I'm hoping he can identify route cause. Interestingly from the VEMS forum the injector fets are known to be an issue, the blown COP is very unusual though.

Getting a bit hacked off with it all at the moment having spent a year and a lot of cash changing the engine and doing everything without compromise.

Looks like I'm on the hunt for some more tires as well!

[stylussprinter]

George, ECU is with the importer today, I'm hoping he can identify route cause. Interestingly from the VEMS forum the injector fets are known to be an issue, the blown COP is very unusual though.

Getting a bit hacked off with it all at the moment having spent a year and a lot of cash changing the engine and doing everything without compromise.

Looks like I'm on the hunt for some more tires as well!

Alex ----- what size wheels do you run I have 4 x R888's to sell that were on my 15x7 wheels , you could have 2 of them at £30 each . Brand new they have 6mm's tread and these still have 3mm's . Put your new pair at the rear up front and my old's at the back . Save you spending £124 each

[se7ensport]

Great offer Rob, I'm running et15 6.5x15 with 195x50 tyres. Guessing yours are 205, what profile tbough? I'll need to have a measure up as I'm pretty close on wheel arch clearance at the back.

[stylussprinter]

Great offer Rob, I'm running et15 6.5x15 with 195x50 tyres. Guessing yours are 205, what profile tbough? I'll need to have a measure up as I'm pretty close on wheel arch clearance at the back.

These are 205x50x15 so just right for the back end but drive with caution on wet road . On track I have room to play with and nobody coming towards me
Probably cheaper for you to collect --- carraige is expensive You're only down the A40 aren't you

[se7ensport]

Just measured up and I'm already 4mm passed the bodywork with 195's on the NSR, 205's would push it to close to 9mm which is just too much. Would be good if I was just down the road as I'd bring the car to you to have a look at the set-up, unfortunately it's a 200+mile round trip.

[stylussprinter]

Just measured up and I'm already 4mm passed the bodywork with 195's on the NSR, 205's would push it to close to 9mm which is just too much. Would be good if I was just down the road as I'd bring the car to you to have a look at the set-up, unfortunately it's a 200+mile round trip.

Measure the driver's side Alex and if that shows a body overlap then the answer's easy . Shorten the panhard rod by enough to make both rear arch overlap equal OR I can make you an adjustable OR if you give me the measurement to shorten it , I'll shorten my old fixed length rod --- if that helps

[se7ensport]

I have the Di-dion rear on mine, I *think* the chassis is straight, but the rear of the body is slightly off by 5mm. I only discovered this last night when I put a straight edge against the wheel to check wheel arch clearance.

I need to get the car out on a flat surface with space to measure. Plan to measure wheel centre to wheel centre on each side and by setting the front wheels parallel (zero toe) they should be in alignment with the rears.

Any other checks for chassis alignment?

[stylussprinter]

I have the Di-dion rear on mine, I *think* the chassis is straight, but the rear of the body is slightly off by 5mm. I only discovered this last night when I put a straight edge against the wheel to check wheel arch clearance.

I need to get the car out on a flat surface with space to measure. Plan to measure wheel centre to wheel centre on each side and by setting the front wheels parallel (zero toe) they should be in alignment with the rears.

Any other checks for chassis alignment?

It will be a good long term thing to do if you ------------------------ Find the exact centre between front mounting points (ie. bolt centre to bolt centre) THEN mark it on the 50x25mm lower chassis cross rail . Do the same for the rear between the mounting points.
Having done that , you can then '' string '' the car out. TWO boxes / logs / whatever at each end of the car , to place straight edges across --- I use ally angle but anything will do . Line the straight edge parallel with the front of the car , another at the rear , just a foot away(not critical) MARK the straight edges at the exact same centre point where you've already marked the chassis (I use TIPEX) . Next mark those straight edges with tipex , say , 3 feet each side of the centre marks .
NOW --- you can put strings/nylon or fine wire between front and rear straight edges on those exact outer marks. From the string to each wheel will ideally be equal , although the measurement will be different from front to rear.

This is a slow but very accurate way to set the chassis up , plus set toe. I accept that most wont want to bother with this extreme but it's something I did years ago when wanting to get my car set up as good as it could be to compete.

[se7ensport]

Great advice.

[se7ensport]

Back on the road, new ECU fitted and rolling road successful; 216BHP with 170lbft at the flywheel, not bad for a Duratec with no internal mods!

ps Toyo R1R's on order for August, my current tyres are comparable to running in wooden cloggs; not too bad in a straight line, but impossible to corner.