The story of Little Red Riding Hood

[Jacques]

Ha ha! No worries. The roads I prefer to drive, are usually narrow, hilly and curvy, with lots of horsemaneuver, wet leaves, dust and dirt and It's been dirty from heavy rain a few times, as I couldn't avoid it. Lower the speed and sneak home, and it doesn't skid out. I always check the weather forecast and take a look at the skies, before leaving home for a drive. If the unfortunate should happen, and it gets dirty, I usually just take a little window cleaner and a couple of micofiber cloths and voila, in just a couple of minutes, it's clean again. I don't fancy coming to a dirty car to take a drive, so it's worth doing. A quick waxing is also on the weekly doing. Modern waxes are so much easier and faster to work with, and saves a lot of times, compared to just 20 years ago. Actually, the Esprit is really easy to clean. It usually drives from late April to early October. The rest of the year is usually cold, wet and not so nice, so that is wrenching time. I should add, that ordering some parts for Winter projects in October, usually arrive here in late May. Oh, those English shops... They are very helpfull and also quite creative in making obsolete parts and what not, but they don't know how to make business with regards to customer relations, I must say in all honesty, no offence. I mean, it's not all sportscar drivers, who prefer to having the car stay dismantled on axle stands for years on end, just because a few bits and bobs are needed. My Esprit is made to drive, not be a garage queen. Sure, an Esprit is a pretty car to look at, but it's driving at seeking suitable victims in german chaos cars that's fun and where a 30 year old Esprit can do it's thing. So, for me, the solution is to project any project one more year, after ordering parts , so patience is needed. When I have ordered parts from USA and Australia, it arrives here very quickly. The only Englishman I know who is quick in shipping parts and stuff, is actually Bibs. Maybe he should take over the whole business?

Take it with a smile. After all, it's better than having no spares at all.

Kind regards,

jacques

[drdoom]

Jacques, my friend, I wish to differ somewhat in regard to our English vendors. The service provided by SJ and Rimmer Brothers has been both sound and prompt, in my experience. Commendable support from our own @Steve V8 in working with me to sort carpet requirements, as well. All this business is just so better enabled due to internet access. By comparison my Elan restoration was conducted '85-'86, when clumsy, overseas phone calls at difficult hours of the day were the order of business. My experiences at that time were consistent with your view, but I find things better by quite some margin these days.

Cheers  

[Jacques]

Thanks, And you are tight, much have become easier with the internet. I'll write you a pm.

Meanwhile at the Danish batcave, I had an hour or two after a long day at work, so manages to press in the 4 Lotac polyurethanebushings. Only waiting for the package from the UK with the remaining two front arb poybushings  

Kind regards,

jacques

[Jacques]

Got some new purple polybushes for the front arb, as one split on installation. Installation tool didn't work, so made my own method and that works really well. The new one just popped in and sit right where it should.

I then spent one hour with a friend on here, to push the right hand side lower wishbone home. Now sits well.

Then spent two hours today trying to loosen up the two nuts that lock the steering ball joints in place. Wouldn't so took out my trusty Proxxon mini tool, and cut them. Two minutes later and one nut came off. Cleaned up thread, lubricated and installed new nut. Same for the other side. Worked well.

New steering ball joints proved to be much longer than the old ones, GGRRRRrrrrr, so again had to "invent" a solution. Luckily there was just enough room it seems, for them to go on. Cannot measure it yet, as I need to install the brakes up front. That'll be tomorrow. Meanwhile I am chasing down bits and bobs for my new LEGO . Lotus Esprit Geometry Optimisation  An installation for measuring toe, castor and camber, easily set up and cost nothing, contrary to the geo-shops around my waters, who demand a lot of money for looking at your car, printing out 1 sheet op paper an dthen do nothing exvept toe at the front end. Nothing else rhat they would bother with doing or correcting. So if I were to use them fo rhte complete setup, I would have to go there several times, as in after each adjustment. Not going to happen. So looking forward to doing it myself.

Also just received the correct 12mm bolts for the LOTAC radius arm poly busings, nuts and I just need to drill the remaining bits to suit, including my new titanium snubber washers that goes for the radius arms and the upper and lower rear wishbone arms. Once the front is ready, I'll commence the rear setup work.

Kind regards,

Jacques

 

[Jacques]

So spent some time fiddling with turning the connecting arm from uprights to steering rod ball joints, the right way  Anyway, torqued everything to spec, regreased wheel bearings and used spring scale to adjust it. The biggest problem here is inserting a new grease cup... Any ideas?

(I filed down the edge in an angle to ease it, but no help really).

I know that endfloat is not shown correctly here, but I got carried away and began to measure all sorts of places just to see if it was okay, and it was. And the brake surface is also perfectly centralised and with no side to side deviations.

I can feel Litthe Red Riding Hood is getting in the mood for dancing soon.

Another question: How much is one spline line moving the steering wheel?

I need that in relation to centralising steering rods, rack and ball joints.

Kind regards,

Jacques

 

[Jacques]

Right, so spent some time today in the bat cave, cleaning the floor, measuring the floor for deviations of being level, and found to my nice surprise, that it's only deviating 3mm over a length of 6 meters. So made up some very thin geo-shims for my LEGO system (Lotus Esprit Geometry Optimization), ready to level the car completely.

Also spent some time taking wheels off and on the car a few times to decide my present ride height. For now, I've settled for raising the front 20mm over the previous setting and leaving the rear as is. I'll remeasure it tomorrow with my rideheight tool. The unnecessary thing, but none the less nice is, that bodywork incl it montage, is only deviating 3mm overall on Little Red Riding Hood.

Rolling about outside a bit to settle the suspension after every readjustment, left me with dirst impression of the new Nitron coilovers being nice and a fair bit harder than the original Lotus parts (although having been changed some years ago). This includes all the new LOTAC poly bushings, apart from the two radius arm front bushings, which is yet to be installed. But before I do that, I want to get a feeling of where I am with the geo and how it measures and feels. Pics are before and after setting ride height. Geo-shims are 1,0mm each.

Kind regards,

Jacques

 

[Jacques]

Spent the day in the bat cave setting up my LEGO system - Lotus Esprit Geometry Optimisation. My wanted numbers are a mix of SE and Sport300 as I altered the car away from SE spec.

1/ Leveling the floor, having shim tiles ready, placing the car center on the surface. Floor is dead level.

2/ Setting dampers to 70mm each (from under spring lock rings to top of bottom housing).

3/ For fun measuring fender height. Max deviation is 3mm left-right-front-rear-cross.

4/ measuring ride height front and rear.

5/ setting dampers to 12 clicks from hardest (a bit over mid-way - standard point of setup).

6/ Using 4 aluminium ramps and a piece of thin green 1,2mm string, I made a square a la Service Notes.

7/ Adjusting the string setup after taking measures, so A=A, B=B and C=C.

8/ setting dots on tape on floor to mark axle centerpoints.

9/ setting dots on tape on floor to mark wheel lines.

10/ Taking measure of 20° in/out on each front wheel and marking on tape on floor.

11/ measuring toe in rear. On spec 1mm both left and right.

12/ Measuring and adjusting rear camber to 1,0° both left and right.

13/ Measuring front camber to 0,9 left and 1,1 right. Non-adjustable on my car.

14/ calculating front Castor to 1,5° on left and right side.

15/ Adjusting front toe to 1° left and right. I think I will change that, though.

16/ Bumping car and re-measure everything in spec.

 

Little Red Riding Hood is now ready to dance her ballet.

Except I need to take the rear apart, brake lines etc, to install new poly radius arm bushings. And remeasure all again. Picture shows string being setup, so not level yet. For ease of use, I made up a LEGO-system work sheet. All setup was done with 2,0 Bar tyre pressure. I am not sure yet, what toe I want on the front, so I will probably make some experimentations for that.

Kind regards,

Jacques

 

[Jacques]

Full geo - the old way.

 To make it more complete, I describe here again, what I did. I hope that I did it right and maybe it's useful to someone out there. Or just myself, for next time I do it.

The old way worked well. Spent the day in the bat cave setting up my LEGO system - Lotus Esprit Geometry Optimisation. My wanted numbers are a mix of SE and Sport300 as I altered the car away from SE spec.
1/ Leveling the floor, having shim tiles ready, placing the car center on the surface. Floor is dead level.

2/ Setting dampers to 70mm each (from under spring lock rings to top of bottom housing).

3/ For fun measuring fender height. Max deviation is 3mm left-right-front-rear-cross.

4/ measuring ride height front and rear.

5/ setting dampers to 12 clicks from hardest (a bit over mid-way - standard point of setup).

6/ Using 4 aluminium ramps and a piece of thin green 1,2mm string, I made a square a la Service Notes.

7/ Adjusting the string setup after taking measures, so A=A, B=B and C=C a la Service Notes.

8/ setting dots on tape on floor to mark axle centerpoints.

9/ setting dots on tape on floor to mark wheel lines.

10/ Taking measure of 20° in/out on each front wheel and marking on tape on floor.

11/ measuring toe in rear. On spec 1mm both left and right.

12/ Measuring and adjusting rear camber to 1,0° both left and right. On spec.

13/ Measuring front camber to 0,9 left and 1,1 right. Non-adjustable on my car.

14/ calculating front Castor to 1,5° on left and right side. Right on spec.

15/ Adjusting front toe to 1° left and right. I may change that.

16/ Bumping car and re-measure everything in spec.

Except I need to take the rear apart, brake lines etc, to install new poly radius arm bushings. And remeasure all again. Picture shows string being setup, so not level yet. For ease of use, I made up a LEGO-system work sheet. All setup was done with 2,0 Bar tyre pressure. I am not sure yet, what toe I want on the front, so I will probably make some experimentations for that.
I have a feeling that I may end up with 0 or a tiny tad toe in on the front. I had plenty of tramlining when I bought the car years ago. Surely don't want that. I had very much toe out.

I need to do it all over again to check after having moved it around outside. At that time I ballast the seats and ½ fuel, and lock the nuts on links and suspension.
The idea is clearly described in Service Notes as for the parallelogram. The tapestribes and dots are from the web. On top of that, I used a roll of fine 1,3mm light green string (to make it precise and so I could actually see it, when walking around the car). Then a long level, a flat metal ruler of 1 meter, 2 pieces of bread with cheese, 1 pencil, 1 roll of painters masking tape (doesn't stretch), 1 bottle of juice, 4 aluminium supports (for a trailer), 1 big 90° angle ruler, 1 protractor to measure angles of 90° and 20° and 1 camber tool with air bubble (can do without and measure it manually).

When you steer straight and are on level surface, ride height is set, tires are set, you can measure camber, either by a small airbubble tool, or manually.
When you have camber angle for lets say the left front wheel, you steer the wheel 20° inwards, as in turning right. This is marked by using the point of center of your wheel hub center, in a vertical plane on to the floor, on a piece of tape sticking to the floor. Set a dot.
Then do the same for the two outermost points of the rim, having the steering straight still.
Then you have 3 dots and draw a line. This line is now your reference to the wheel being straight.
Now, measure 20° angle from the center point, outwards, forward and rearward, as you would steer 20° left and right. Set a point as far away as you can, and draw a line with the flat metal ruler. More distance makes more precision. Take your time.
Now measure the camber again. Then countersteer to 20° outwards, as in turning left, and measure camber again.
You now have 3 values of camber for each front wheel: straight, 20° left and 20° right.
Now, depending on what the numbers are, you can calculate the castor.
If the two 20° measurements for a wheel, is calculated like this:
What you are trying to achieve, is a camber difference from turning left and right.
So, if both measurements are negative, subtract the small number from the larger number.
Then multiply that with 1,5 and the result is your degree of castor for that wheel.
Negate any + or - when adding or subtracting.
If you on the other hand have one negative and one positive cambermeasurement from turning the wheel, then add the numbers together.
Multiply by 1,5 and the result is your castor for that wheel.
Finally, if both of your camber measurements on one wheel are positive, then subtract the smaller number from the larger number.
Then multiply by 1,5 and the result is your castor for that wheel.
Repeat the calculation for the other wheel.
It's really simple and does not require a lot of expensive cumputer tools from race shops.
The picture above is to give you an idea of taping. But, do the string square first as I wrote in the previous post. Then you can do the other precedures for camber, toe in, and castor.
Use a big level together with the big 90° angle tool, to ensure vertical correctness when taking measures and making dots on the tape on the floor.
The multiplication factor of 1,5 is a result of measuring at 20° angles. If you measure on say 15°, then multiply by 2. If you use 10°, multiply by 3.
If your floor is not completely level, son't worry, as the 4 stands are adjustable in height, and both those and the car can be set up level by the use of the thin floor tile vinyl shims I showed in the above. Just buy a piece of 2 x 1 meter, cut them to say 35 x 40cm and you have a stack to play with. each is 1mm thick. Good enough to use for this purpose.
Don't lift the car on to these vinyl shims. Then you unsettle the suspension. Instead place whatever stack you need in a corner or more corners, behind the tires, and roll on to them. Measure with the car on them, if it is now level, straight, perpendicular and across. If they slide, just use a bit of painters masking tape to make them sit tight together.
Only draw with a thin line pencil as thick lines makes it imprecise.
The final time I do it, I'l luse all new nuts for the ones that need to be loose for pre-tensioning the bushings.

Little Red Riding Hood is now ready to dance her ballet.

I used my LEGO form, as a guide to write down what I found usefull to know, both now and for the next time. It's nothing special, just a practical work sheet. Hopefully this made some sort of sense

I'll keep it in the cars file.

Kind regards,

Jacques
 

[Jacques]

Today I reset front toe to 0 and rear camber to 1,1°. We'll see how it fares.

Actually, I am very interested in how Little Red Riding Hood will drive, as I have done quite many thing at one time, without testing each thing seperately. Usually I do only one thing and then drive to see how it performs. This way I can also better have a feel for what it actually does. But, all these things were necessary, so it had to be in one stage.

even though measuring wheel arch height cannot be used to set suspension, I measureit and can later on see, if something I do to the car, combined with reading ride height, will change those values.

Light weight parts are on their way. And some better stopping power.

Question: where exactly to measure rideheight rear? I became a little bit in doubt about the rear end point to measure. I use this:

 

Kind regards,

jacques

 

[AndyPG]

2 hours ago, Jacques said:

Question: where exactly to measure rideheight rear? I became a little bit in doubt about the rear end point to measure. 

Usually the bottom of the rear sub frame where the rear radius arms bolt on.

Andy.

[drdoom]

Jacques, it may be OK to run 0 degree toe however I believe it is convention to run either plus or minus rather than neutral. I presume this to generate slight pre-load of the steering components in preference to having constant dither which I would expect to promote wear. Not certain of this, open to feedback from others.

[Jacques]

In that case, would you, with the mods I have made, suggest a slight toe in or a toe out?

And what level of wear are we talking about?

Kind regards,

jacques

[drdoom]

I think you'll want to try the minor front toe-out (never at the rear) specified for the later series cars, as you seek a sharp and responsive chassis. That measure of toe either way would not generate enough scrub to materially affect wear. So your focused work on getting all components and settings in top form should narrow down the quest to eliminate wandering off track, should any still be troublesome. The substantial size of tires will always translate road surface variations vividly but stable tracking in general should be expected once all is resolved. The rear is actually more pertinent to stability when it's off spec so be very sure of alignment there. Beyond the mechanical, there is finally the question of aerodynamic influences particularly if the car is good at legal speeds but gets nervous well above. For that we can discuss underbody flow and fore-aft rake in particular.

Great that you share this exercise, will be a benchmark car when you're done I'd say! 

[drdoom]

Upon further reflection I recall one more alignment check of particular importance - bump steer. In case you are unfamiliar this is the change to toe over the arc of suspension travel, and is quite critical to the behaviour of a Lotus. I will describe the method in rough terms, in case you wish to get on with setting for optimal bump steer. With wheels/tires on and suspension/steering assembled EXCEPT without spring and damper car is set up with means to elevate and lower front end  through full  range of travel, typically by use of a floor ( trolley? ) jack. Best to have blocks under all 4 tires to establish adequate clearance for lowering car to full compression height with jack in place. Care is required to ensure car cannot roll off the blocks and jack,  and multiple sheets  ( 20 per side ) of newsprint layered sheet upon sheet ( not folded tight as sold ) between the front tires and blocks to eliminate scrubbing stiction, so permitting reasonably free suspension travel. Smooth boards of plastic or pressed fibre may be helpful if placed between tire and newsprint. Once preferred toe at static ride height is established the car is raised or lowered incrementally from static with stops to record the toe at various points in the travel. You will find the toe does vary as consequence of imperfectly matched articulation, steering links versus suspension links. You may X-Y graph the relationships if helpful but the simple objective is to pursue minimal variation in toe over wheel travel. As you will appreciate, this can have quite a bearing on how the car will track over uneven pavement and, in general, added toe-out is usually worse than added toe-in. Adjusting the bump steer pattern on an early Esprit is done by altering the mounted height of the steering rack. The rack pick-up points on the chassis afford latitude in placing the rack for height, and I expect it will the same throughout the Esprit series. It is a bit of a trial and error procedure as there will likely be a swing to toe out through one segment of wheel travel and to toe in through the other. This is measured as compared to static, and you will be lucky if what you measure shows your current rack height to be optimal. If not then plot the results with alternate rack positions until rack height which yields the least variance in toe from static is found. You will then likely have optimized this important characteristic but be wary of any added toe out in compression as this will correlate to the loaded side when cornering. By the way this should be done on any Lotus not purchased factory new, unless one is certain the front end has never been worked on. 

Best regards

[Jacques]

Thanks a lot for the explanation. It has never been worked on , except for now.

This seems also to underline the importance of how (at which position) the suspensionrelated bolts are tightened under load of two persons in the cabin and ½ full tanks, as the twist or preload in the bushings are different, and the values of effect they represent under various suspension travel, are different, thereby affecting height, and thereby also affecting bumpsteer as a consequence of wrong height to turn - wrong angles to certain input.

I'll have to think a method to set this up.

On another note, reagrding high speed stability, I added a 1992 front rubber spoiler some yearsa go, which seemed to give a tiny bit (may just be an impression), of added stability, when driving fast. Mind, at the whole time, my caster has been wrong. Anyway, to add to that stability, and as a consequence of the car now being faster with the engine and exhaust work, and a fair bit of more ponies, I now bought a Sport300 front rubber spoiler, which is much deeper, and should create less lift which in turn should give a bit of added stability when high speed. Low speed wouldn't create enough difference to make a difference, I believe.

Before that, I'll take a testdrive, and see how it feels at say 150 km/h. Then I may widen the front track a little bit, and repeat. When I bought the car year ago, the front toe was very wide, far out of alignment. It tramlined heavily and it was a real struggle to cope with for over 600 kilometers to home. Once adjusted, the car behaved much better. Still, untill I took the car apart some weeks ago, it had a little tendency to behave sensitively at higher speeds, as angles were out. At low speed nothing strange could be felt.

Btw. I have a couple of new poly bushings to insert onto the steering rack. I couldn't reach them from the sides, so now that the car is able to move around, I'll go underneath and see how to deal with that. I wonder what these do to steering? If they are jsut eliminating some rubbery feeling (not slop), then fine. If not, and they only contribute to oversensitiveness, I'll extract them again. We'll see.

I think I have to work on one thing at a time, so I can better feel what it does and doesn't.

So, going back to your explanation of bumpsteer, could I possibly affect or correct that, by for example shim up (or down) the vertical position of the tie rod ball joint? Or does the whole rack have to be moved up or down (as on an axis)?

Kind regards,

Jacques

[drdoom]

Lots of good thinking there, Jacques. In response to your points, yes, the adjusting of bump steer is also done via change of tie rod end height where practical. In race cars where Rose joints are the kit this involves add/subtraction of simple spacers so easy-peasy. Street machines more often use a tapered pin on the TRE so not suited to spacing in/out of the corresponding tapered locating hole in the upright link as I would expect to be the case on the SE. 

Agree with your views on aero, the new SE I track tested was notably stable on smooth pavement to 200kph, BTW.

Can't see a correlation between arm bush preloads and bumpsteer. Corner weights sure, but bump steer arises out of slight disharmony of links articulation so I don't see a connection to the bushes preload. Poly mounts on the rack should not be problematic in any way, will perhaps sharpen the feel minutely.

To recap on chassis behaviour overall the Esprit offers a fine platform as designed. My only quibble with the SE on OEM Goodyear Eagles was that the response to steering input was a touch too soft. Might have been the tires as much as anything, though I believe feel was at least partly diminished due to the reduced castor. You have made numerous changes with a bearing on this, from wider rims/tires, firmer spring/damper specs and on to the latest efforts. Your plan is sound so enjoy and keep us posted!

Cheers

[Jacques]

It's been a hard days night, and I've been workin' like a dog.

Everything loose, both arms off and on the floor, but one bolt STUCK in the right side arm. I've tried heat, cold shock, torque (not to break it), penetration fluid, but to no avail.

Good ideas are very very wellcome.

Kind regards,

Jacques

 

[Jacques]

I forgot to mention, that  BIG hammer didn't help either. If I apply more force, I will smash the radius arm.

So I am kind of stuck too.

Kind regards,

Jacques

[Steve V8]

A good wire brushing to the visible thread + penetrating oil, if that doesnt work theres something wrong. Just sheer it off and press it or drift it out.

To help with set up...

The V8 used split rear toe adjustment shim plates, these can be slipped in from either side without the need to completely remove the trailing arm.

Just loosen the bush mounting bolts to add or remove, and they are interchangeable with the earlier 4 pot one peice shims. Well worth doing if you intend to adjust toe setup on a regular basis. 

[Jacques]

Thanks, I'll try that. I have bought an assortment of the newer shims, for the same reason.

I think as the offending bolt in the right side arm is already on the floor, me working on it, that it's corroded to the inside of the radius arm. I'll atttack it tomorrow.

Have you tried mixing acetone and automatic transmission oil as a dissolver/penetrating lubrification

Kind regards,

jacques

[drdoom]

Acetone and ATF in combination has been repeatedly promoted in forums as the best penetrating fluid. No experience with it myself, as yet.

[fjmuurling]

Drill a couple of small holes in the nut and or use a nut spliiter. Most of the times a nut splitter doesn't split / break the nut but in those case the nut will be stretched (making the inside of the nut bigger).

[Jacques]

The nut came off with no drame when on the car. I have the radius arm at home now, and mixed atf and acetone in an oil can and lube it every hour. We'll see how that works maybe tonight. If that atf&acetone mix works, I'll be sure to mention it here.

Thanks,

Jacques

[Jacques]

Success!

So, I bought a small bottle of some ATF fluid and mixed it ½/½ with acetone and poured it into a small oil can for the purpose. It strongly colours anything, incl. nitril rubber gloves.

Applied a few drops every ½ hour or so for two hours, each time trying carefully to see if I could work it loose. Second time it gave a small click (not like breaking a bolt), and third time it rotated, fourth time I could drive it a little bit into the radius arm tube, and fill the hole with the penetrating mixture and finally, it could be driven out without too much force. That was actually very easy and with no drama. And I can be a tiny bit temperamental, just like Little Red Riding Hood

It is by FAR the most efficient penetrating bolt loosener I've ever tried. Highly recommended. Much better than all the spray cans I've bought.

As it is ½ acetone, remember to keep it far away from any paint or linoleum (which it dissolves).

It is clear, that even though the bolt looked fresh and nice on the outside, it's never been lubricated. Until now. On the first picture, one can clearly see the lube mix on top and the amount of rust from inside the tube on the bolt. Nasty! The funny thing is, that the nut itself was no problem, so the arm came off the car with ease.

Now onto drilling the radius arms to 12mm, to adapt to the 12mm metric bolts that supports the Lotac radius arm poly bushings. Little Red Riding Hood is delighted that she is not limb and doesn't need a new leg, erh..  new arm.

Old rubber bushing measures 11,7mm both ends of the tube so together with 7/16" bolt clearly narrower than the 12mm new style setup.

Thanks all!

Jacques

[Jacques]

Today I had the radius arms machined to adapt to the thicker M12 bolts that is needed when using the newer LOTAC polyurethane radius arm bushings.

Before doing so, I made the following observations, which I find interesting:

One or the rubber bushings I've removed from the car measures 11,8mm bore, plus a little wear in one direction - 11,9. The other end of the same bushing measures 11,8mm.

The other rubber bushing I've removed from the car measures 12,2mm both ends, but a little ovalised both ends. The measurement are the smallest adn also from the middle of inside the tube.

I then measured both Lotac polybushings, and they measure 12,1mm both ends, both bushings.

I measured both old 7/16" bolts to be 11,7mm,

I measured both new M12 bolts to be 11,9mm.

I had the bores in the radius arms bored to precisely 12,05mm.

That means in my view, that the old rubber bushings were changed according to my file from p.o. to two different ones, one being an old production, the other being a newer slightly larger production.

It also means that the production of the new bolts are normal quality, not high quality items. I measured other new bolts to be similarely under spec. by 0,1-0,2mm.

The black 12,9 steel bolts I also measured are typically 0,05-0,1mm thinner than spec, so more precise.

I will not use the 12,9 special black bolts, as I was clearly warned against that. I will use the ones I bought from a spares dealer.

It is clear, taht if one wants to machine a part to fit, measureing the related parts , such as these bolts I bought as M12, must be measured beforehand and consideration made to the size of the new bore.

With this drilling/cutting, it's more precise and just enough to lubricate and move, but avoid hammering/knocking on the bolts when driving. I am satisfied with that.

It's a clear feeling that there's now less play and that things are fresh and precise as intended.

Kind regards,

Jacques