S2 toe recommendations

[Stevensonjr]

I have an original 1965 series 2 that I finished restoring last year. It’s a ball to drive but at anything over 50 mph it requires constant steering attention with no center feel. I am running with 1/8” toe in (I think). The local tire shop couldn’t align things for me because the car is too small for their machine. I used the string and ruler method to get where I am now. I run Michelin 155 HR 13 tires on the street, no track work, I’m 80. 

I’m not sure the toe in is correct for these small tires, any advice would be welcome, I think Chapman built in toe in only because “people will muck it up if they have too many adjustment options”. What is the suggested toe in for a street car? Mine is really too light and twitchy at speed.  
Thanks, Bill

[Dave W]

Bill

A 1/8" toe in should be enough. I would make a trammel bar from wood or tubing. Make a mark for the toe setting on tape apply across the tires, then roll the car back, (180*) and re-check the difference between the toe markings. Did you replace the control arm bushings during the restoration? My guess is that you do not have enough caster, because the bushing(s) have taken a set, [distorted]. Check your front suspension bushings and the location of any spacers. To increase caster you want to move the lower arm forward and the upper arm rearward. You are somewhat limited with the series 2 design and spacers that you can pack. A 1/2 degree increase in my Seven made a world of difference, in self-centering.

Also if you have a lot of body rake it can decrease caster or high tire pressure will affect centering.

[Stevensonjr]

Dave, I did change all the bushings in the car, front to rear. What tire pressure are you running? I’ll take a look at the spacers (washer positioning) on the upper and lower control arms.  Thanks, Bill

[jbcollier]

1/8” is a bit much.  I would go with 1/32” to 1/16”. Try that first.

[Dave W]

It is not a good comparison, because I have a conventional L/S control arm suspension system, that can be easily adjusted. My set up is 1mm toe in, 5.5 degrees of caster, .6" scrub, and my camber has been steadily reduced down to just .5 degrees of negative camber, and 20 PSI in the tires.

[jbcollier]

S2 caster is not adjustable.  The only way to do it is to physically modify the lower suspension arm.  Some people try to force an adjustment using shims but this will place loads on the trunnion and upright they were not designed to take.  YMMV

[CarlB]

you might want to check and make sure the rear suspension is in line with your front suspension.

[Stevensonjr]

I knew my 7 was straight because when I rebuilt it I stripped the old body off, cut off the full racing cage and cross measured every section of the frame before I had it media blasted and powder coated. I had a factory drawing of the frame and when I was thru it matched every Series 2 dimension. I changed all bushings and rebuilt the rack and pinion steering gear. I inspected the A arms for bends and all were correct. The triumph 7 differential and shortened axles were jig built and square to the frame and front axles.

The only real adjustment I had was toe in, which I thought I had done correctly.

I decided to check my setting on toe in again. I put the car on my lift last night and raised it up to elbow level. The right front wheel had 1/16” toe in, the left front had 0” toe in. The first time I did it on the floor, bending over. At 80 I’m too old for that. I used the string method again and set both front wheels at 1/8” toe in, measuring twice! I can always back off that setting later.

I drove the car this morning and can say that it feels better at 75 than it did at 45 previously. The twitching is gone and the steering wheel holds center without constant correction. Sometimes simple answers fix things, I should have known that I did a crappy alignment job the first time. 
Cheers, Bill

 

[jbcollier]

Could just be all the bushings settling after being replaced.  I set mine to 1/16” after a rebuild.  Soon found the steering to be flighty and induce significant sphincter puckering.  Checked the toe again and it was a 1/4”!  Reset it and it drives like a dream now.

[Stevensonjr]

Thanks for giving me something to blame it on, settling bushings, never would have thought of that! I might check it again to see if it “settled” some more.

[Stevensonjr]

After driving a few more miles I settled on 3/32” toe in. Seemed to smooth out low speed turns and center properly with no twitchy feel at highway speeds. Speaking  of highway speeds, it’s a little unnerving to realize you are at the same level as the running boards of the Suburban next to you!

[jbcollier]

Yeah, I also have a Lotus Europa and some chaps on the lists add metal reinforcing bars to their doors.  “Great” I say, “ Just as long as you are hit by another Europa, you’ll be fine.”  Basically Lotus Sevens (and Europas) have the crash protection of a motorcycle with 70% less visibility.  Drive carefully out there.  I drive like I’m naked and invisible.  Even then it can get a bit exciting at times.

[Davemk1]

On 10/11/2023 at 5:07 PM, Stevensonjr said:

After driving a few more miles I settled on 3/32” toe in. Seemed to smooth out low speed turns and center properly with no twitchy feel at highway speeds. Speaking  of highway speeds, it’s a little unnerving to realize you are at the same level as the running boards of the Suburban next to you!

What rear toe are you running?

 

dave

[Stevensonjr]

The rear end of the original Lotus 7 was a Triumph 10 live axle unit with no provision for any adjustment. I installed a narrowed Triumph 7 rear end with a 3.63 gear. No toe in or any other adjustment on this axle either, just quite a bit more strength. Some later lotus reproductions or copies have a independent rear end which enables most adjustments.

[jbcollier]

It is possible to induce small amounts of toe in with a live axle, especially with Sevens if you are bracing the axle.  Whether it is desirable or not, I don’t have the expertise to say

[7Westfield]

Back in the day, some racers would tweak the live axle housing to get a bit of negative camber.