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Learning how to build Lotus Seven replicas...together!
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PostPosted: March 4, 2023, 8:47 pm 
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The wider front track is to help prevent understeer and not critical.

I would check the toe on each end loaded. That means when checking the front, the front wheels are chocked (I use beveled corner 4x4 posts about two feet long). Use a ratchet strap to pull and hold the car forward against the chocks enough to take all the play out of the joints and bearings as if you were driving. Check across the car from wheel to wheel instead of adding two separate measurements to the chassis. There are a number of ways to check the tow without having to get under the car. One way is to use straight tubes or angle iron against the outside bulge of the tires as high as practical and run the tape measure underneath. The loaded toe should be zero. Do the same for the rear.

Lift each wheel and observe the tread from the front or rear, then rotate the wheel by hand on the bearings, watching the tread at one spot. I've had defective tires where the tread moved from side to side. I don't know if it was a belt or molding issue but the tire shop took them back once I showed them the wobble.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: March 5, 2023, 8:49 pm 
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i have measured from side to side and come up with the same settings, however the rear track is difficult and in the past has resulted in one wheel with zero toe and 1/8" on the other.

when accelerating hard, the effect appears less so maybe the rear is changing toe when power is applied.
i do not think this is due to movement in the rear alignment as the suspension squats but it could be going toe in, not an easy thing to check, the rear camberis probably going more negative

or the front is going more toe in as the suspension rises or camber is reducing from negative to positive also causing the toe to move in.

the car stops in a straight line.

i do not have any bushes in the front suspension it is all hiems and none are worn, they are all new, there is no wheel bearing play and the top and bottom ball joints are good.

maybe i should look at bump steer again to see if it is going toe in on droop, it may be that it goes toe in in bump and droop

i will also measure the camber in droop and any caster change.

i could just raise the front suspension an inch or two without changing anything else to fool it into thinking i am accelerating when i am cruising, and if this improves the situation , i will measure front geometry from that, adjusting at ride height to the new geometry ( toe ).

likewise i could do the opposite in the rear.

l'll keep thinking about it, i must get some batteries for my temp gun.

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PostPosted: March 6, 2023, 8:38 am 
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For squat toe without removing the coilovers, you could place a board across the back and use a few concrete blocks or if that is too difficult, place two or three 5 gallon buckets on the rear deck and fill evenly with water as needed to squat. If still too heavy to take off, drill a hole you can duct tape over from the inside if you want to retry.
For easier adjustment access, you could back on to or jack to place ramps under the rear, then raise the frame to level at the front. Of course, light ratchet strapping on the rear would be toward the rear/chocks or ramp lip to the rear since the wheels would move forward when loaded. Worth checking even with new parts.
Hopefully any bumpsteer is toe in versus out, especially on the rear.

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: March 6, 2023, 1:08 pm 
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Location: meadview arizona
so today i looked at the car, i started measuring the heights of the steering arms.
i had spent a lot of time on the bump steer to get it to stay still or toe in a little.
having changed the caster as recomended, the bump steer was way out of adjustment due to the steering arms raising at the spindle (front steer) as the caster was increased, so that exercise will have to be performed again.

i noted that the rack knuckles were at different heights, this appeared to position the drivers side knuckle slightly lower than the steering arm ball joint, the passenger side was the opposite with the knuckle slightly higher than the steering arm ball joint.
this would cause the drivers side to go toe in on a small undulation and the passenger side to go toe out on a similar bump, this meant that my steering was turning depending on how large the undulations in the road were (like truck rutts on a freeway)

however under acceleration the front would lift to a point where both steering arms would droop, toeing in.

i remeasured the lca inner pivots to the ground and as expected the passinger side was higher than the drivers side, almost exactly the same amount as the knuckles.

looking at the car infront of my roller shutter the rear of the car was down on the drivers side where it came to rest after a long drive saturday and considering my body weight (208 lbs ) was not in the seat, it would probably be down even more when driving.

this would affect the chassis height even more on the passenger side front, compounding the steering arm angle problem, so i will have to address this before any other faults are detected

i will have to add 200 lbs to the drivers side seat and footwell, readjust the coil over on the drivers side, this would have shown itself if i had some corner scales.

by jacking up the drivers side rear until the car was level in the back, the front pivot points all came in line

this must have been playing havoc with the bump steer.

this all goes back to when i found the coil overs damping rate was stiff on one side and soft on the other.

the plot continues, will our intrepid builder ever find the actual problem? stay tuned for the next episode " how many turns on the spring seat will level the car" comming to locostusa soon.

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PostPosted: March 7, 2023, 8:45 pm 
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so 5 full turns brought the car level with me standing in the drivers seat.

the front lca inner pivots were level side to side.

readjusted the caster 9 1/2 deg. and camber to 2 1/2 deg. on both sides.

toe was 3/16" in over all or just under 1/8" each side

bump steer was 1/8" more toe in in 2" of bump and 1/4" in 2" of droop.

drove the car a couple of miles cruising at 85 m.p.h., the free play i had in the quick release steering wheel hub was not a problem and apart from a heavily cambered road the car went straight, previously, the car would wander and i would have to correct it but i would not feel it going until it had gone due to the play.
now the play is neutral as in i can wobble the steering in the play and the car still appears to go staight.

after the road test i put some center punch marks on the column hub which tightened the hub up somewhat.

i will go out this saturday to a show and give my opinion after that drive due to all the other times i thought i had corrected the problem and hadn't.

it is hard for me to remember what and why i did things in the past these days but i must have screwed up monumentally with the rear coil overs and their settings, also not taking my weight into account setting the car up level.

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PostPosted: April 17, 2023, 5:38 pm 
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my final opinion of the cars handling.

in a straight line at slow speeds there is still a tendancy to follow rutts in the pavement but is well within the bounds of control to the point that i can let go of the wheel to put my gloves on.

at high speeds it goes arrow straight, like 90 + mph ( on a private road in Mexico ).

cornering is excellent, my nerve goes before the grip does and responce is instant.

i am still playing with tire pressures and have 25lbs. all round but would like to go a little lower, especially in the front.

tire temps are fairly even considering that i am running 2-1/2 degrees of camber.so the inside is about 3 degrees hotter than the outside and most of my driving is done on long straight roads.

Florida roads have a lot of camber which fluctuates, this does cause some change in direction that i have slight difficulty in controlling due to the play in the steering wheel quick release boss which uses a hexagon to mount, i can feel the steering moving in the "play" area with the changes in road surface, i have today ordered a new quick release unit that uses splines which are, apparently much better in the amount of play, my original is 11 years old so i can't expect much from it.

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PostPosted: April 26, 2023, 1:26 pm 
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i purchased a splined quick release unit from speedway, it was significantly larger than the hex type.

after removing the elecrical panel and some covers to access the demountable joint between the upper column and the power steering unit, i discovered that half of my play was in the through bolt wich was 6mm dia.
clearly this also had to be attended to.

while i was in there i thought it would be a good time to install a tilt column which i had lying around.

all went fine, a little machining here and there to fit the larger splined unit keeping the steering wheel in the same position fore and aft.

when finshed i had no brake lights, no horn and no bleepers on my turn signals.

when removing the old column i had disturbed some wiring, tracing the bleepers was almost inpossible as the two connections had broken so i started that from scratch splicing into the left and right signal wires.

next the brake lights, from memory, 12 years, i supplied an independant circuit for these, how i did it was not in the memory files but i had a couple of clues.

the b/l switch had two terminals on it but only one wire the spade terminal was a 90 degree as space was confined so i looked for another 90 terminal on another wire under the dash somewhere, found it but had to loosenup the column to pass it through, plugged it on and hey presto they worked.

the horn was a complete mistery, there was a missing relay, i am baffled, no one else has worked on the car and i would not have used it for checking other relays as there is a spare relay in the fuse box.

i put all of this down to being 73!!!!

anyway job done and steering vastly improved.

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PostPosted: January 4, 2024, 11:23 am 
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so now the car drives very straight no wandering although there is a tendancy to climb up the camber, the more camber the more this tendancy feels but it is not exessive and most of the time is un-noticable.

i have noticed that the brakes are able to lock all four wheels on some road surfaces, the front will lock before the rear.

the front tire temps are much lower on the front than the back, if i feel the tires after a two hour drive, the rear has some warmth but the fronts appear to have no temp at all, this with 25lbs in all four.

i will drop the pressure in the fronts down to 20lbs and will search for my temp gauge so i can be a bit more scientific about the measurements.

i am running 1/8th. tow in on the front but also may consider a little more to generate some heat.

i had not noticed this before but i have only driven the car in Arizona or in summer in Florida, in AZ the roads are much more agressive on tire wear than here in Florida.

any thoughts on this would be appreciated

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PostPosted: January 4, 2024, 10:18 pm 
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1/8 toe is a lot adding more will make the steering mushy I believe.
And may make it change directions depending on which wheel has more weight?
Airing up the tires should make them less squirmy?

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PostPosted: January 6, 2024, 11:05 am 
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Unless you have overly soft bushings in the control arms I don’t think there is a need to run more than 1/8” toe in the front.

Most 7’s are rear weight biased, so all things being equal (tire size, air pressure, etc), the rear tires will run hotter than the fronts in steady state cruise.

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PostPosted: January 6, 2024, 8:54 pm 
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Any chance there is binding in the steering system or load carrying ball joint?

Does it return to center well and go straight?

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PostPosted: January 14, 2024, 1:43 pm 
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there are no flex bushings in the suspension front or rear.

the steering self centers without promping it

i do have electric power steering

i think that i am exagerating the problem really, but a change in the front camber could do the trick, it is common to have different settings on each side.

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