kmead
Old enough to know better
Tires, brakes, try to find parts for what broke, fix what broke...
Not likely to get a good nights sleep
Scuderia Ferric Oxide
- Thread starter fiatfactory
- Start date
Not likely to get a good nights sleep
Steve Hoelscher
True Classic
Endurance racing is all about preparation. Of course with a new car, you don't know what will break. That first event will be all about sorting out the car.
In 2013 I participated in a 36 hour enduro record in Spokane, WA to see if we could get into the Guinness Book of World Records. Straight through for 36 hours.... It was Looooooonnnnnngggg.... Great memories though. We drove a 5 series BMW at the track, had a great time. I was quite happy to be done though, by the end, all of us were like "want to drive, naah, you go ahead..." As for the record, it turns out Guinness does not define a 36 hour event as done in a single car, and there are others in Europe where you can go, and have a group of cars as a team and drive for more than 36 hours straight. We did this the old fashioned way, one car for 36 hours. Oh well. It was a great time. Good friends, of which some are no longer here.
Rupunzell
Bernice Loui
Endurance racing is much about preparation of the car, team, support for all involved, organization and dealing with some of the most remarkable things that could and does happen.
Testing is mandatory to sort out the car and all involved. If that is not done to a high level of preparedness, well before the event remarkable surprises happen.
That said, endurance racing can be one of the most rewarding challenges any moto fan can get involved with.
Bernice
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fiatfactory
Steve Cecchele
I couldn't agree more with you both...
Unfortunately my friend Eddie just told me the other day he won't be a starter, financial issues with work hours and covid etc for him, but that's OK as there's still 6 months to go before raceday. I'm sure he'll come along and give a hand this time around, maybe the next run he will be a starter.
So I figure if I only have a team of four the schedule is maybe something like this. An 8 hour race is actually a lot easier to manage, I sort of wasn't looking forward to the long night / managing fatigue (for me personally too being driver/bulder/team owner) over a 24 hour non stop race.
Raceday is 14/15/16th October 2021
Thurday afternoon practice 4 hours, limit of 4 vehicles on track at once, short track only.
Scruitineering is Thursday morning, that's the big one for me.
Friday / Saturday. Race day 8 hours each day, Friday short track, Saturday long track.
My thoughts are 100 minute stints, and allow 5 minutes for refuel / driver change / vehicle check (hopefully quicker but I'm being realistic)
100 minutes should be enough time to get well settled into the car, but not too much time, so that fatigue / dehydration will still be manageable.
8 hours is 480 minutes.
Stint one, Driver one : start - 100 mins.
1st refuel and 1st driver change at 100 minutes, back out at 105 minutes.
Stint two, Driver two : 105 minutes - 205 minutes.
2nd refuel and 2nd driver change at 205 minutes, back out at 210 minutes
Stint three, Driver three : 210 minutes - 310 minutes.
3rd refuel and 3rd driver change at 310 minutes, back out at 315 minutes.
Stint 4, Driver 4: 315 minutes - 415 minutes
4th refuel and Final driver change at 415 minutes, back out at 420 minutes
Stint 5, Driver TBD: 420 minutes - 480 minutes
fastest driver of the day (on an average lets say, not just a blinder) gets to go out and do a second stint for the day, and it's the last 60 minutes to the chequered flag, and hopefully with the car running well, gets to push hard to the end.
I will definitely get in a test day or two before hand., not a chance I'm going to turn up untested for an 8 hour run,. Engine will need to be run in, possibly two sets of pads and two sets of rotors bedded in, and at least two set of tyres need to be scrubbed...
My mate Mark is a definite starter - unless there happens to be a covid lockdown right when he's due to fly in or something not in our control like that. He flies in from Sydney on Thursday morning at 8.30am, then he's picking up his rental motor home RV thing at the airport and driving out to the track so should be there by 12 lunchtime. He should then have enough time to get a couple of decent 30 minute sessions in and learn the track and post a time / present his gear / license etc. I'm sure his Thursday evening will be spent fitting go-pro's and making sure that is all good to go for the next day. His RV motorhome is going to be base of operations, and a place to kip
Martin , Mark and myself will be driving the long track for the first time ever on Saturday, none of the test and tune days are long track, but that's cool and will be interesting data
Con isn't a definite yet. I think maybe he wants to see the cage in the car before he commits, but say's he likes the way the builds heading. He's entering one of his Mini's in Aprils event, so I'll go along and spectate / check out the "lay of the land" , hopefully with Martin.
So there are bragging rights and an extra hour of drive to the chequred flag to drive for. A drivers entry fee and share of the tyres/fuel etc could be ... remember could be... for up to 320 minutes of drive time over the weekend. I think that's good incentive to keep it smooth/fast and always pointing in the right direction, like I said not just FTOD, but a mean lap time / average of 10/20 laps / no penalties.
SteveC
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GregS
ProjectX
Steve H, interesting discussion here. I'm trying to get my head around whether to add more negative camber at the top of the front strut or at the camber bolt on the bottom of the strut. Just wondering if I can measure camber gain (loss) statically by loading up one side of the car and jacking up the other side a bit to simulate body roll, and measuring the camber. I'm wondering if my negative camber is reducing too much on the outside wheel when cornering.
This is on my track X, weight 700kg, coilovers f 360lb, r 290lb, current camber -3 deg, caster 6 deg, no sway bars.
My front tyres, 185/60 13 are wearing more on the outside than the inside.
fiatfactory
Steve Cecchele
I'll leave it to Steve H to give you the full answer, but my guess is "insufficient total roll couple"
I would say more than -3 camber will begin to produce unwanted side thrust (camber thrust) which makes the car "grab" any road irregularity and under braking excessive camber makes the car unstable.
SteveC
fiatfactory
Steve Cecchele
With my desired shift of the top strut mounting surface upwards - I measure 38mm which positions the step on the strut shaft pretty much level with the OE sheetmetal for the turret top when the suspension is at full droop - I can also move the centreline of the strut shaft inwards by almost 30mm each side if I want to.
I havent done the drawing and worked out the camber curve with the strut at this inclination, but as you say, the camber curve inproves as does the static camber. A couple of things I was wondering about as how does inclining the strut affect the wheel rate (if at all) and how does it affect steering effort (does it increase thrust at the pivot point?)
Would there be any benefit from altering the plane of the spring? i.e. angling it to the strut shaft, as this is what Fiat did on later Ritmo's, and it was supposed to have been for reduced steering effort.
I also get to (to some degree) set where on the strut shaft static height is, there is approx 80mm of strut shaft movement with the standard bump stop assembly, normally I'd split the travel roughly 2/3 compression and 1/3 droop, would you do the same more or less?
SteveC
Steve Hoelscher
True Classic
You are correct. Given the quoted rates, the car will have excessive body roll and thus wear the outside of the tires excessively. That much body roll will likely have the camber curve well into the positive range.
Steve Hoelscher
True Classic
Inclining the strut that 30mm has an insignificant effect on the motion ratio and thus the wheel rate of the spring. I was able to move the MR2 top mount more than that with out noticeable effect on wheel rate. Same for steering effort. At low speed steering effort is lower due to the reduced contact patch. It does have an effect on the load the diver feels through the steering wheel due to the change in position of the contract patch relative to the steering axis. All of this goes out the window as the dynamic loading changes with speed. As you push the car's limits the driver will hardly notice the effect.
As for the angle of the spring relative to the strut, no. Universally, competition strut designs use Coil Over type springs that use a common centerline for the spring and strut.
The amount of compression and droop travel, from static ride height, is typically the result of the strut's stroke, the height of the bump stop and the chassis' ride height. If you're using a coil-over type spring and you have more droop travel than free spring length, you can take up the space with helper springs. These can be had at very low rates and since they are in series with the primary coil-over, they will bottom out before the primary spring moves. The springs on my car are stiff enough I don't bother with helpers.
hotx19
Daily Driver
Steve so if your springs are so stiff that you don't use helper springs then do you have any droop ?
Or does you spring become loose on the strut?
I have fitted helper springs too allow for some droop but I don't really like them as they take up a fair bit of usable suspension travel
Thanks
John
Steve Hoelscher
True Classic
The strut has about 12mm of droop travel beyond the free length of the spring. If the car was to lift a wheel long enough for the spring to become unseated it won't matter because the spring seats are deep enough to prevent the spring from miss-aligning.
One reason for the use of helper springs on excessive droop travel is to maintain some amount of suspension load and force the wheel to full droop in the effort to maintain some amount of surface contact. This can be important for torsen type differentials that will open up if the inside wheel looses grip. A light helper spring can force the strut to full extension and keep that tire in contact to prevent the diff from opening.
Another reason to maintain wheel contact is to keep the roll center properly located. If you lift an inside tire when cornering the roll center for that axle instantly moves to the contact patch of the outside tire. That moves 100% of the roll induced weight transfer to the outside tire of the opposite axle and overloads it causing loss of grip.
Rupunzell
Bernice Loui
We did Koni 8610 series damper inserts originally for Volvo (these were low buck back then) on the LeMons car. These Koni dampers have WAY too much piston travel for the exxe. One of the ways to deal with this would have been to take apart the damper, shorten the piston rod, put it all back together. Too much work for four and too involved at the time as there was lots of other stuff that had to be done. Instead of helper springs, we applied cables as a full wheel droop limiter. They worked good. This seemingly insignificant detail is important, if the wheel gets fully unloaded then comes back into contact with the road surface the change in spring/damper rate is fierce. This can result in a wide variety of suspension/chassis control issues for driver and car.
Bernice
Bernice
Steve Hoelscher
True Classic
Greg, have a few minutes this evening to delve into this a little deeper.
In theory you could jack one side up and add weight to the other but I am skeptical of the practicality of the exercise. Jacking won't move the weight through the roll center. Remember that body roll comes from the center of gravity, acting through the moment arm (the distance between the CoG and the roll center), to transfer weight from the inside tires to the outside tires. Jacking up one side doesn't do that. Nor does adding weight to the other.
The light spring rates you have noted I am sure are causing the chassis to roll excessively. On a strut car that not only causes a loss of static camber but also, as the outside suspension compresses, the camber curve transitions to positive.
On the X chassis, or most any production strut chassis, you never want the angle between the virtual control arm and the steering axis (the line drawn between the lower ball joint and the strut's top mount, to exceed 90 degrees. The camber curve transitions from negative to positive at 90 degrees. So as the car rolls, it looses static camber and as it compresses the outside suspension the angle of the control arm and strut becomes greater. So you are loosing negative camber on two fronts. This is why its so important to keep the chassis flat when cornering.
As discussed previously, the ideal solution is to move the strut tops inboard as far as practical, then adjust static camber at the upright's strut mount. This provides a more acute control arm/strut angle and slightly raises the roll center. This permits the car to be lowered and maintain a roll center that is above ground level.
The photo below is of my MR2. Its important to note that the front suspension is a virtual copy of the X1/9. The original geometry is nearly identical. Note how, despite the body roll, the outside front tire is perpendicular to the track surface. This is the result of considerable modeling of the geometry discussed above. The data at this point on track logged right at 1.5 lateral g.
The rear suspension is just as important. In the photo below you can see how square the outside rear tire is the the track surface. This is a heavily cambered corner and the data indicated just short of 1.7 lateral g. You can clearly see how much load is transmitted through the tire as it is pulling away from the wheel rim.
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hotx19
Daily Driver
Thanks Steve
One more question please
With the high springs rates that you run and basically I have used your setup advice too tune my car how much droop travel is enough obviously I have way too much nearly 50mm
What should I realistically be aiming for the problem is with nearly 50mm of travel I'm getting very close too full strut travel which is far from ideal
Thanks for your help again
John
Ps sorry for the Hi jack Steve C
GregS
ProjectX
Thanks for the advice Steve. I dug up a photo of my car cornering, as you can see it does in fact have a fair amount of body roll. I think I will put my front springs (360lb) on the back and get some stiffer springs for the front.
My front lower control arms are close to horizontal when static, so I could raise the front slightly, and slot the strut tower holes to gain some neg camber that way, and fine tune camber with the camber bolts as suggested. I hope this helps the camber gain without having to resorting to a sway bar on the front.
Attachments
Rupunzell
Bernice Loui
On the Mazda rotary powered LeMons X, spring rates on front can be 500lb/in to 600lb/in, rear 400lb/in to 475lb/in. Depending on chassis-suspension set up at that time. Not a lot of roll. Tires are 195/50/15 dunlop direzza on 7" rims, weight about 1,700 pounds.
In the PBS race prep book, they recommend 200lb/in on all four corners with their anti-roll bars front and rear. Number of the PBS modifications are designed to preserve as much suspension travel as possible. Consider how much suspension travel will be needed with a cornering load of say 1G?
Bernice
In the PBS race prep book, they recommend 200lb/in on all four corners with their anti-roll bars front and rear. Number of the PBS modifications are designed to preserve as much suspension travel as possible. Consider how much suspension travel will be needed with a cornering load of say 1G?
Bernice
Steve Hoelscher
True Classic
I think people worry about droop travel too much. My DSP X1/9, for much of its career, had stock length struts on it. Given the low ride height, even with the camber plates mounted on top of the strut towers, the droop travel was probably a full inch more than the free length of the spring.
I never bothered to do anything about it. Later I put a set of full custom Koni double adjustable struts on it. They were much shorter. I even ran a zero droop setup on the MR2 for a while. The zero droop didn't work as well as I had hoped but the experiment was valuable in the knowledge I gained.
I wouldn't worry about the droop. If you are using an OE spring perch, you will want to run some kind of travel limiter to prevent the spring from missaligning. If you are using a coil-over type spring then a tender spring will solve that problem.
fiatfactory
Steve Cecchele
you can get flat wire section helper spings, they take up a lot less room in the spring pack when collapsed, maybe something like this will help?
Faulkners Flat Section Helper Springs
These helper springs are designed to go coilbound and then return to the full free length making them suitable for retaining location of the main spring.Available in the following diameters -1.9
SteveC
fiatfactory
Steve Cecchele
I looked around and found the stock specs for the strut shaft inclination and came up with two numbers...
in this picture the section A-A shows the front as 11 degrees and section C-C shows the rear as 9 degrees.
and I found a reference to "king pin inclination" in the specifications and features for the 1972/1973 series 1 European specification X1/9 of " approx.13 degrees" ...
I'm kind of hoping that you have done all this modelling before ( @Steve Hoelscher ) and have settled on a number in degrees of strut inclination / steering axis inclination which gives the best compromise camber curve, in relation to the other front suspension pick up points being standard (and the same as your MR2!) save the top mount moved up / in.
Is there any advantage to also dialing in more caster up front by moving the top mount backwards slightly?
as the rear is also very important, is it worthwhile inclining the rear strut axis more that standard also? what sort of angle do you feel works best for the rear suspension?
I'll work out my front and rear track widths in the next couple of days, I just sorted out the disc / spacer / wheel stud mount up this afternoon, so was able to mount a wheel and a tyre to check clearances and range of motion properly for the first time today. (properly - well with only a "virtual top mount position)
Also being lemons / BEERS I am budget limited in my suspension component choices. I do have a reasonable array of parts taken from the two donor X19's.
Up front of donor two (the chassis being used) was a pair of very old Koni struts, so this is what I'm going to have to use. I do have a brand new pair of these Konis on the shelf as a spares, so should a strut fail on race day, the parts are available.
From the two cars I also have two pairs of series one rear strut housings that are of the removeable gland nut on top style, so I can fit a replacement insert.
From car number one I also have four "Pedders" Sports Touring inserts, These and the housings lets me build two pairs of rear struts, so again I have spares for raceday. Car number one came fitted with 350 lb rear spring, free length a little longer than the stock rear spring. I was going to use this at the rear and have some springs made / find some in 450lb rate with similar free length to the stock spring.
this keeps my lemons dollars spend to the minimum (top mounts x 4 and a pair of springs is what I'm outlaying) and will give me a definite improvemment in mechanical grip over the standard pickup up points / standard spring rate.
still with a light sway bar up front , solid mounted with adjustable driving links to be able to fine tune the total roll couple
Any additional thoughts?
When the lemons run is done, I have a set of Matt's strut housings and 8610 Konis / coil overs etc available, I also plan on running the car at the "Fiat nationals" in 2022, and there are no cost or tyre treadwear restrictions for that event...so there will need to be a "lemons budget setup" this time around, to go with the 220 treadwear tyres.
SteveC
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