kgh
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Posts posted by kgh
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I took the MX5 to Anglesey on 6th March with some of the Nutzers.
With more front camber and higher tyre pressures I hoped that the tyre wear on the R888s would be reduced. Unfortunately the plan didn't work. The tyre wear in the middle of the outside half of the tread was slightly less pronounced because it was over a slightly wider area. Grip from the front seemed initially better but ran out quite quickly if pushing hard. I guess this was the result of the higher pressure. Some pictures showing the front camber working
I'm not sure if I'm imagining it but it seems to me that the outside of the offside tyres are carrying all the weight.
The airfield at Blyton near Gainsborough has been leased by a chap keen to develop a driving centre. The plan is quite ambitious and involves building a tarmac track nearly two miles long. To get experience in running a track day, and some income, MazdaOnTrack organised a day there on 19th March. It's a 320 mile round trip for me and as I cannot carry more than 2 spare wheels I didn't want to risk totally wearing out the R888s so I went on the Toyo T1Rs which had done about 9000 miles. The car was great. The additional front grip reduced the car's tendency to understeer and the rear stayed in line. A little exhuberance was all that was need to make the rear step out in a controllable way. I got the video camera that you can see in the above photos working; the key seems to be switching it on. Here are the results (watch out for the car on the extreme left as I approach the circuit entry)
The circuit, laid out on the main runway, was dusty early on but a clean line developed although it stayed very slippy off that line. It was a good day and I hope the plans are fulfilled.
Some more pictures are here
I talked to the chaps preparing MX5 Mk3 race cars about the tyre wear. They are experiencing the same and have found no way to avoid it. It looks like part worn road tyres are going to be my best option.
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Well the handling seems sorted but we need to move on and find where the noise is comming from. It's time to look outside of the box and that's something we are good at.
I try to make a distinction between handling (cornering speeds etc) and road behaviour (tramlining, pulling etc).
What I meant and what I didn't make clear was that it was the road behaviour that felt a lot like it did when the car was younger. Mainly in how it responded to bumps.
However the problem has now been diagnosed and fixed. It appears that the Mazda dealer that fitted the Eibach lowering springs, two and a half years ago, incorrectly assembled the top mount on the front offside damper. This interfered with the positioning of top of the spring as the suspension loaded and unloaded. The noise was assumed to be the spring correctly positioning itself.
My heartfelt thanks go to the WIM team who found and corrected the problem in a very short time. It's sad that this is the level of competence we have come to expect from dealers.
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Ken,
have you looked at the ARB bushes? Loose/worn bushes can allow the ARB to flap around in the bushes making noise and making the ARB less effective.
I have a set on Lexie, (Not from WIM) and I find they improved turn in and generally tightend things up do to having no rubber to compress before they operate.
h
Thanks for this. I had already decided to remove the front ARB drop links and see what happened. I did and nothing happened as the noise was still present.
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The car pictured with the new drop links is mine.
So why replace the drop links?
The car has an intermittent noise from the suspension when the front offside wheel goes over a bump. An inspection found a loose drop link and with the known weakness of the OEM links a change seemed desirable.
The car is 39 months old and has done 32000 miles quite a few of which have been on the track.
What difference have they made?
The car feels a little tighter and quieter when going over bumps. In fact it feels a lot like it did when it was lowered and first aligned by Tony in August 2007
Should I fit them to my car?
If you have a drop link problem then you should. The cost is less than OEM drop links.
If you have fitted or intend fitting different anti roll bars then you should and really should if you haven't changed them yet.
If you take your car on the track then you should consider fitting them as there are quite a few instances of the drop links breaking.
These drop links are adjustable so that they can be fitted so that the joints suffer the least wear.
Can I fit them myself?
Yes but if your car is getting on it will be difficult to remove the old drop links. Access to a lift and a ramp will help.
My links were fitted on a lift and then the car was moved to the ramp so that the links could be adjusted to the best position with the suspension loaded.
I'm dying to know; did they fix your problem?
No. The noise is still present but has reduced in intensity but increased in frequency. I do not suggest that either of those changes is a result of fitting the new links.
What are you going to do next?
I'd hoped that you would tell me
The noise is mostly a solid thunk with sometimes a twang added. (I know, I know it's difficult to describe a sound).
At times it sounds as if a wheel is catching the wheel arch but there is no sign that this is happening.
As I said it is intermittent. I can drive down a road with no noise and go back down the same road and the noises occur.
The same thing happens when I drive onto my driveway that has a slightly raised kerb.
All suggestions are welcome.
Thank you for reading this,
Ken
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would a 205/40/17 not have a stiffer sidewall ?
pressure calculations should also take in the distance, in the sprint series we were running r888s fairly low around 22-28 as there was little chance of getting them hot so relied on more surface area for grip
if its not wet you can always turn the 888's around and go non directional
I was thinking that the 205/40/17 tyre would be a better fit to my 17x7 wheels than the 215/45/17 and would reduce the tread width and distortion.
Track day distances are greater than sprints and tyre temperature does become a problem.
I was thinking that I should swap the tyres side to side if it was dry (hopefully remembering to put them the correct way round before driving home)
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We do this with slicks, but i've never experienced this on road/track tyres....... Any indication of the toe settings because this is also very different on slicks?
The consenus on toe is to use zero toe all round. The stiffer sidewalls help the turn in and front toe out is not necessary. I would assume that 'zero toe' means zero dynamic toe.
See here for Toyos setup info for spec Miata's on 888's:http://www.toyo.com/sites/default/files/im..._Guidelines.pdf
They recommend 32 to 38 psi hot and suggest starting at 32pis and go from there.
When I went to Mallory, with the 888's first outing, I had them at 30psi cold, don't know what that equates to hot.
h
Thanks.
This is one of the articles I found. The Mk3 is considerably heavier than the Spec Miata and the standard Mk1
I have heard other MX-5 drivers saying that they intend to refit the tyres so that they can use them on the opposite side. This does suggest that they also experience uneven tyre wear but at the time I wasn't having this problem so I didn't look into it any further.
I am ploughing a bit of a lonely furrow with the Mk3 on the track at the moment. There are a number of Mk3 race cars in development at the moment so I may be able to get help from them.
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My Toyo R888s are showing the same type of wear (without the delamination) so I decided to research the problem using my friend Google.
The results seem to be that this type of wear is caused by the tread part of the contact patch (ie the bit between the sidewalls) distorting under the cornering forces. The distortion occurs because the sidewalls are very stiff. If the distortion results in a bulge this soon wears away giving the impression of a shallow groove worn away in the tread. Some of the R888 information I found referred to the "Groove of Doom". The cure is to increase type pressures and increase camber. The effect is apparently worse if the wheel width is at the lower end of the allowable range.
I had found a list of recommended tyre pressures for the R888 based on the weight of the vehicle. So I set the pressures to 29psi cold and saw them rise to 34-35 hot. The Google searches suggest that the tyre pressures should be 40+ when hot.
So I think I need to do this
1) Get the R888 refitted so I can swap them side to side (and get a bit more use out of them)
2) Change the alignment setup from Fast Road to a more aggresive track set up
3) Use higher cold pressures to achieve 40+ psi when hot.
4) Consider using 205/40/17 instead of 215/45/17 when I replace the tyres
As always comments and suggestions are very welcome.
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I, too, enjoyed this day in the December sunshine.
That's an interesting comment about Surtees and McLaren from Sean. One of the joys of the MX-5 on track is the corner you can take without braking or lifting. Surtees and McLaren are like this but it leaves you very little time to do anything about the turn in for Clearways and if you're not sure exactly how you intend to do it you have a bit of a problem. :cool03: My bit of a problem ended in an unintentional drift round most of Clearways. The back end stepped out and opposite lock stopped it but didn't bring it back into line until the drift bled off enough speed whereupon it snapped back quite quickly leaving me heading in the right direction. A few more laps and I figured the best approach was to ignore McLaren, the exit from Surtees takes you to its apex anyway, get the car straight at or just after this apex and use the width of the track to bake hard and change down for the entry to Clearways. This seemed to wotk.
This was the third outing for my Toyo R888s and the first fully dry day. They certainly give a lot of grip so all I have to do now is work out how to use it. The R888s showed the same sort of wear I had with the Yokohama Paradas but I think I can shed some light on the problem. I will post more in the Tyre section.
Ken
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most new cars are stored for a good while before being brought and driven
I wonder if the manufacturers take any preventions
Mazda MX-5s are notoriously delivered with high tyre pressures. They set them high at the factory for shipment and the dealers are supposed
to set them correctly as part of the PDI -
Were you understeering across the kerbs by any chance? Saw tooths can take chunks out of road tyres!
Not knowingly.
The wear, front and rear, is in only one of the tyre blocks in the tread pattern and is in every one of these blocks. It seems unlikely that the kerbs could be so exactly aligned with the tyre tread.
I suspect overheating is the culprit and I need to drive shorter sessions.
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which direction is cadwell park ie; clockwise or anti-clockwise ?
Clockwise.
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I took my MX5 Mk3 (NC) to Cadwell Park for a few laps (well 120+) on Friday. I kept the tyre pressures to 30-31psi, measured when hot, all round. When I changed the wheels on Saturday I found this:-
The nearside front has large chunks missing fron the blocks to the right of the large groove whilst the offside front is fine.
The rear tyres showed the same wear pattern but with smaller chunks missing.
The tyres are Yokohama Parada Spec 2.
Any thoughts?
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I'd be up for this except I'm still waiting on the P5 suspension mod. Does that make a difference?
I am intrigued by this statement 'The benefit of these will mainly be felt by the "as sold" owner who wants to reduce the body roll during cornering.The links can be used to add preload to the existing anti-roll bars'
If you preload for left hand corners do you have to dash out with a spanner before right hand corners?
Point taken :blush02: but hay at least i'm trying to be innovative :tongue2: .. I have a highly modded NC ready to trial a set so we can go from there.
Don't get me wrong I'm not being negative.
Intuitively it seems best if the arb arms are horizontal when the vehicle is at rest but I can find no geometric/trigonometric reason why this should be so.
Any play in the joints will obviously reduce the arb's effectiveness so the rose jointed droplink should improve things if there is any wear in the existing droplinks.
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I'd be up for this except I'm still waiting on the P5 suspension mod. Does that make a difference?
I am intrigued by this statement 'The benefit of these will mainly be felt by the "as sold" owner who wants to reduce the body roll during cornering.The links can be used to add preload to the existing anti-roll bars'
If you preload for left hand corners do you have to dash out with a spanner before right hand corners?
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Going back down the 17" route now!
235/40/17 on 8" rim would keep the same diameter as the standard 205/40/17 although I think it is a bit wide for what I need!
The 225 options on a 7.5" rim with the tyres I want (Toyo T1-R) is 225/45/17 which will increase the profile from standard and the diameter by 0.6". That shouldn't make too much difference I guess. They don't seem to have a 225/40/17?
Maybe the most sensible option would be to go 7.5" rim with 215/40/17 tyres although this will reduce profile, the diameter by 0.5" and therfore more importantly show the gap between the wheel and arches! lol.
Someone tell me to stop being such a fanny and just buy some!
Stop being such a fanny and just buy some
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I checked the ride height of my NC 2.0 Sport - Eibach springs fitted by dealer on 3rd August 2007
Front 345mm - Rear 340mm
I looked in the front wheel arches and found twisted bushes!
I released the bushes and checked the ride height again
Front 340mm - Rear 340mm
Has the 5mm drop upset the alignment?
A fraction.... Drops that i have imaged where between 15 and 20mm and they needed attention.
A tell-tail sign apart from any handling changes is the steering wheel position.
I looked up the cars last alignment report (7th July 2008) which showed the ride height to be 355mm all round which can't be right
When your machine is working again
I'll arrange to drop in and let you see it.Are you on 16" or 17" wheels?
17"
Then assuming the height is still the same then it's needs checking again.
I measured the heights again this morning and the height is 340mm all round.
Interestingly since the last alignment I have acquired a second set of wheels and have changed sets 3 or 4 times. I change the wheels one side at a time using two jacks. This would shift a lot of weight to the other side (even more than the body roll when cornering
). Could this have an effect? -
I checked the ride height of my NC 2.0 Sport - Eibach springs fitted by dealer on 3rd August 2007
Front 345mm - Rear 340mm
I looked in the front wheel arches and found twisted bushes!
I released the bushes and checked the ride height again
Front 340mm - Rear 340mm
Has the 5mm drop upset the alignment?
A fraction.... Drops that i have imaged where between 15 and 20mm and they needed attention.
A tell-tail sign apart from any handling changes is the steering wheel position.
I looked up the cars last alignment report (7th July 2008) which showed the ride height to be 355mm all round which can't be right
When your machine is working again
I'll arrange to drop in and let you see it.Are you on 16" or 17" wheels?
17"
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I checked the ride height of my NC 2.0 Sport - Eibach springs fitted by dealer on 3rd August 2007
Front 345mm - Rear 340mm
I looked in the front wheel arches and found twisted bushes!
I released the bushes and checked the ride height again
Front 340mm - Rear 340mm
Has the 5mm drop upset the alignment?
A fraction.... Drops that i have imaged where between 15 and 20mm and they needed attention.
A tell-tail sign apart from any handling changes is the steering wheel position.
I looked up the cars last alignment report (7th July 2008) which showed the ride height to be 355mm all round which can't be right
When your machine is working again
I'll arrange to drop in and let you see it. -
I checked the ride height of my NC 2.0 Sport - Eibach springs fitted by dealer on 3rd August 2007
Front 345mm - Rear 340mm
I looked in the front wheel arches and found twisted bushes!
I released the bushes and checked the ride height again
Front 340mm - Rear 340mm
Has the 5mm drop upset the alignment?
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Some killer roll going on in the first photo, you on standard suspension/antiroll bars ?
Yes; the suspension is standard apart from the Eibach lowering springs.
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Oh dear an incorrectly placed wim sticker does it again
What happened with the spin.... It looked like it was on the straight?
It's at the exit from the Hairpin onto the start/finish straight. Too much, too soon ...
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I took my WIM sticker to Croft at the weekend. I stuck an MX-5 to the back of it as you can see here:-
I must have put the car in the wrong place on the sticker and unbalanced it because this happened:-
If the car doesn't wash off it will be going with the sticker to Rockingham.
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Make sure the washer bottle is full...surely that's abit OTT
Some could hold a gallon or two
How much weight would that be then, obviously enough to make a difference?
My dear old Mum taught me the rhyme - "A pint of water weighs a pound and a quarter". So a gallon weighs 10 pounds.
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And at least I can't make it any worse...
Definitely not..... The poor MK3 really needs some Puredrive TLC
Should I be reassured by this? Its my car he's going to mess with.
I am very excited for you.... The Puredrive suspension on the MK1/2 i exemplary, i have the good fortune to calibrate some cars on these units and it's a delight to be part of the overall package.
How advanced are developments?
I have no info on this. You'll see the car (unmodified) tomorrow for a 2000 mile geometry check.
Why wim choose GAZ suspension
in Suspension
Posted
So will I! Ride in Mk3 always available