Demystifying toe alignment specifications

[Drive Stainless]

If it was as easy as you say why doesn't everyone run these.

Actually, come to think of it, don't Mike Lund and David Teitelbaum both own Lotus Esprits? They may have a good answer.

[FABombjoy]

Attachment 66964

Doesn't seem that safe. The body fell off and the frame tipped over

Changing the upper taper is fine with me but probably not something most owners are comfortable with. I'm guessing it opens up a world of adaptable off-the-shelf options. These bolt-on Lotus wishbones, as well as adapted or custom custom parts. Something that doesn't need shims for adjustment would be nice but I'll bet the Lotus arms are ultra light.

DI's adjustable caster system is nice in that you can fine tune more than shims, but you are range limited as major increases in caster will put the wheel very close to the fender. Ideally caster is a job for the UCA as it's just sittin' there, mostly doing nothing.

[Timeless]

A large amount of toe in is used on some older cars but mainly trucks that have a lot of play inherent to the steering system. By giving them a lot of toe, when all of the play is taken out, the wheels run pretty straight. Modern cars run much tighter and have a lot less toe to have better road feel, go straighter, get better gas mileage, and tire life. Always try to align by the manufacturer's specs unless you are doing something custom like racing. Racing specs are a whole other world. When you start talking about corner balancing you are starting to get into that area of specialty. A typical 4 wheel alignment, that requires no parts (except shims and washers) should cost no less than $80 and no more than $150 and take less than an hour. On Deloreans the suspension was designed by Lotus, they are world renowned as suspension experts and have a rolling wind tunnel. Major manufacturers go to Lotus Engineering to have their cars fine tuned. If you are going to modify it you should be at least as knowledgeable as they are if you expect to improve on it. For the majority of owners that choose to have their alignment done by a shop, if the car is set to the specs given by DMC the car will perform about as good as it gets assuming no worn, bent parts and a good set of tires properly inflated. For the few owners that want to do it themselves, learn as much as you can before doing it and get the proper equipment or try to borrow it. Some of it can be made. A set of plates and some BB's can work as slide tables for example. Ride height is all important so take as much time as you have to to get that set first. All of your other measurements will be affected by that so you have to get that right. I do alignments but only so I can drive a car that I did a lot of work on till I can get it to a rack and have it done accurately. I get close but not perfect.

[FABombjoy]

Weird bump, but a chance to say that I have a set of Esprit arms on the workbench awaiting clean & repaint.
Also a very expensive taper reamer that will be used twice.

[deloreandmcxii]

I've combed this thread and I can't find if anyone directly answered one of the original questions. Over what distance is the .12" of front toe measured? 14" of rim or 23.2" of tire or some standard 28"?

I'm trying to get my close myself using shade-tree methods. And just to understand the concepts. I'll eventually get a real alignment (having adjusted my ride height up somewhat recently - I suspect introducing some wander due to throwing the toe out a bit)

If it's at the rim: .12" over 14" rim yields nearly .5deg. So are the bulletins NOT meant to revise the toe angle published in the original manual - but only provide a more detailed procedure?

If it's over 23.2 we get .3deg. So the bulletins would be suggesting less toe than originally published. But they don't make it clear that's their purpose.

Where did all the alignment equipment providers get .2-.28?

The table for REAR toe distance to angle conversion does work out to suggest it's over the ~26" of rear TIRE.

[FABombjoy]

I've combed this thread and I can't find if anyone directly answered one of the original questions. Over what distance is the .12" of front toe measured? 14" of rim or 23.2" of tire or some standard 28"?

It seems to be the static tire size standard. I did the math on wheel & tire size, and looked at published specs from around the internet. The 28" standard was the only consistent thing. Expressing an angle with a length measurement is anarchy.

Source	Degrees
Actual F - 3mm	23.2" Diameter		0.29
Actual R - 3mm	26.1" Diameter		0.263
ST-34-1/82 Figure 4			0.26
28" defacto 1970s Smartstrings		0.245
Hunter 2008 DMC 16908			0.24
Hunter 2016 DMC 10270			0.24
Hunter 2017 DMC 16606			0.233

I went with .22 for my front. The size of shims makes the back clunky but went with about 0.15L and 0.18R. It is good.

[Bitsyncmaster]

I've combed this thread and I can't find if anyone directly answered one of the original questions. Over what distance is the .12" of front toe measured? 14" of rim or 23.2" of tire or some standard 28"?

I'm trying to get my close myself using shade-tree methods. And just to understand the concepts. I'll eventually get a real alignment (having adjusted my ride height up somewhat recently - I suspect introducing some wander due to throwing the toe out a bit)

If it's at the rim: .12" over 14" rim yields nearly .5deg. So are the bulletins NOT meant to revise the toe angle published in the original manual - but only provide a more detailed procedure?

If it's over 23.2 we get .3deg. So the bulletins would be suggesting less toe than originally published. But they don't make it clear that's their purpose.

Where did all the alignment equipment providers get .2-.28?

The table for REAR toe distance to angle conversion does work out to suggest it's over the ~26" of rear TIRE.

I did the "shade-tree" setting for my front toe after replacing the parts. If you have to little toe in you won't like highway driving because it's a constant moving of the steering just to go straight. I adjusted each wheel about a half turn to get more toe and now driving is great.

[deloreandmcxii]

Thank you both! I may actually be experiencing two issues. A bit of play in the steering shaft and perhaps the need to toe in a little. They probably add together to make it feel worse.

The symptoms are just like you describe, Dave - a bit wandery at over ~65mph.

I probably shouldn't overthink toe, if I toe in *a little* too much because that's what FEELS right on the road, the only downside is a slight bit more tire wear (if we're talking a few extra 10ths of a degree). But if the original factory spec was .5deg, well I can't see that being too crazy.

[FABombjoy]

Some of your wandering may be due to cross caster, which seems to affect our cars. My own had at least a degree and I know another DIYer that had the same problem.

The "before" pic here shows it on another car:
https://timemachine16606.tumblr.com/...heel-alignment

Last year I fixed caster using the DPI lower links. They're good but you can only adjust caster a bit using the DPI LCA system.
This year, if all goes well, these Lotus UCAs will help get the front end exactly right

https://i.imgur.com/kp7o0La.jpg

[deloreandmcxii]

My front suspension is 100% DPI. Rear is mostly DPI, trailing arms and upper control arms are factory.