Rotus group?

[ptegler]

the Probe lever setup is wild to say the least. One thing to watch.... that switch. that rides the steering column. and the current path for the relay used makes a difference as to whether it self-cancels.  .... (relay coil resistance)

after the re-wiring   (for those who don't know about this switch)   One lever is turn (up/dn) and high/lo beams  in/out.
plus momentary high beams flash all within finger tips reach

[Marek]

On 2/13/2026 at 12:06 PM, rotus8guy said:

Good morning Rotus owners. I've come out of the woodwork to join the discussion, because I'm again working on my long derelict Rotus. Mine is chassis #101 delivered to me by Dennis Hedges in 1995.

Welcome back!

 

I don't think I've seen one of these with louvers on the side of the bonnet or that close to the cowling.  What is the engine in the car?

[rotus8guy]

Greetings @Marek

I had the louvers done by a hot rod shop (long gone) in Forest Park GA. Definitely helped with airflow. The engine was built for me by Phil and Ray Baker. 1962 Olds turbo 215 block, Buick 300 crank, and Buick 300 heads.

You mentioned "sleeved jam nuts" on Bring a Trailer about our front suspension. I've had no issues with the F-250 tie rod ends as ball joints, but I'm always up for improvements. Where did you find such a thing?

I finally have time for the car after long work on my retirement house, so I'll be on here and Britishv8 gathering tips and tricks.

Cheers,

John

[Marek]

The aforementioned balljoint sleeves.  They are the handiwork of the previous owner.  The pictured balljoints are "Moog Problem Solver"s.  I can imagine the Problem Solver or your F150 ball joints are sufficient on their own.

 

 

Here you see the original ball joints and the problem they suffer.

 

 

(Note that the nut in the second picture was later correctly wired!)

Edited February 18 by Marek

[Marek]

 

A shot of the hood louvers from the factory.  I have no reason to believe this was a standard fitment and could be unique to this car.  There is an air-air intercooler below the rear most louver section and the car does struggle to stay cool under sustained boost.

 

[rotus8guy]

Thanks for the pics. My searches haven't turned up anything like that. 

Rotus's "ball joint" throughout production was the Ford part ES-150R, a tie rod end on various heavy trucks. Moog labels all their ES-150R as Problem Solver quality now 🤷🏻‍♂️

The sleeve nut looks like a good addition if it could be found.

Do you know the thread size?

Cheers,

John

[rotus8guy]

A little searching, I answered my own question. The thread is 3/4"-16.

I haven't found a sleeve nut, but Speedway has suspension tubes threaded to 3/4"-16 that you could cut the end off. Not too cost effective at $15 per nut, but it'd work.

[Marek]

McMaster-Carr carries coupling nuts in 3/4"-16; though also not cheap.  The real answer here is longer rocker arms to reduce the number of exposed threads.  I'd like to give the factory the benefit of the doubt by saying the exposed shaft is intended to make the balljoint sacrificial in a shunt, but that seems optimistic for an early 80s application.

[rotus8guy]

Mine doesn't have as much exposed thread, though I don't remember how much negative camber I had dialed in. The sleeve nut looks like a non issue for me.

[rotus8guy]

Redcloud1728 on Bringatrailer (who I assume to be Lee Kaiser, the Rotus designer) has had some very interesting and opinionated things to say about Rotus and Chris Custer over the last few years.

[ptegler]

somewhere back in this thread(?) there are a couple comparison shots of the later cars with slightly longer a-arm ends (less threads exposed)
A gentleman her and I had discussed this very point...we compared photos, and it appears longer arms were used later in the production run.
Mine also have longer arms with only 1-3 threads showing, and my camber is ~ +0.5°

 

Regarding the BAT poster.... take it with a BIG grain of salt. 
I'd personally visited the dealership multiple times, almost buying one new in 1988.  But the X-wife wanted a 4x4 for all the camping we use to do in Western MD  (I'm in Baltimore)  Some assets are still in the hands of x-employees in the general area to this day..  Many stories abound, those that gained were happy, those that didn't ....well.... 
The most I got away with was a sweat shirt  9back then anyway!  took another 34 years... but I got one. (and a new wife obviously)

 

ptegler

Edited February 19 by ptegler

[Marek]

Well summarized.

 

I too visited the factory, but was too young to serious consider buying one at that time have only a set of original literature.

I've been in contact with a former long-term employee who may have fixtures, molds, and documentation and have considered visiting them to make note of what is available.  Feel free to encourage me (I have family in the area.).

[Marek]

Rotus might be unique in the use of a rocker arm front suspension and in theory it should be an advantage.  But Caterham never went down that road and others on this forum have commented that they are not fans.  Any comment @Croc, Slingshot, or Mazda?  (or others?)

[ptegler]

Cats simply went dual a-arms as nearly every other car out there, most likely simple parts availability and or road testing safety regs etc.  Orig Sevens, the leading upper a-arm were the sway bar itself. The rubber end compliance was there as a solid mount would have stressed the upper inner pivot as the sway did not rotate on the same axis as the arm.  The Rotus design does not need nor benefit from a sway bar.  Take a glance at any F1 car (simply easy to see during TV shots)  you see no shock, nor even a shock strut, as their upper arms are the same see-saw scheme (albeit bell-cranked etc)   I've got an old copy of the Lotus suspension software. In the past I'd modeled my  Triumphs, Miatas, MGBs  etc.   when working the Rotus suspension measurements, The Rotus design, tests as if a Z-bar is mounted up front!  Nearly zero roll with the wheels on the ground in a corner, yet normal compliance of a single wheel over a bump.  Probably why they got away with such lightweight springs 125lbs in the back 115 up front 
(or do I have that bass-ackwards?)   Personally, maybe it's the ol' geezer in me....  first hand experience is the only justification for any comments. If you haven't driven both, any comment is mute.

v/r

ptegler
 

[ptegler]

@Marek I think we chatted about a meet up once before.  Had Chris's son at least acknowledge my email, but never got a follow-up as promised. So I didn't push it.
Funny to as to this day the dealership is still there, albeit diff name/company/dealer etc.
ptegler

[Croc]

6 hours ago, Marek said:

Rotus might be unique in the use of a rocker arm front suspension and in theory it should be an advantage.  But Caterham never went down that road and others on this forum have commented that they are not fans.  Any comment @Croc, Slingshot, or Mazda?  (or others?)

 

The Caterham CSR front suspension is push rod with rocker arm design (by Multimatic).  I think it works very well.  I have never heard anyone say the Rotus was a flawed front end design because of its use of rocker arms.  It all comes dowwn to the articulation and range of motion that affects the wheel during cornering.  I don't think anyone ever did a formal study of the Rotus suspension so I am not sure where the negative comments come from - never seen them myself.  

 

I have seen some Locost 7s use rocker arm fronts bbut they are are unique builds - nothing standardized for production like the Rotus or Caterham CSR.

 

 

 

[ptegler]

I've always been amazed at the idea that cars rely on just two bolts to support all the weight up front (two lower front ball joints)  Cars sits on the shocks/springs sure, but everything presses on that short, lower shock mount to ball joint area of the front lower suspension.  REAL or not, the idea that the front weight now sits on top the upright. just seems right for some reason.  The Lotus software really can't make any determinations as to whether it's better or worse than other designs,  as it for angular and speeds of motion of travel type analysis, rather than 'track feel'.   Again, the only way reality can make a suggestion, is a talented driver's (or group) direct comparison 'seat of the pants'.  Even then I think I'd still prefer to do that test myself, for a multitude of reasons!   :-)
v/r
pegler  

[pethier]

16 hours ago, ptegler said:

I've always been amazed at the idea that cars rely on just two bolts to support all the weight up front (two lower front ball joints)  Cars sits on the shocks/springs sure, but everything presses on that short, lower shock mount to ball joint area of the front lower suspension.  REAL or not, the idea that the front weight now sits on top the upright. just seems right for some reason.  The Lotus software really can't make any determinations as to whether it's better or worse than other designs,  as it for angular and speeds of motion of travel type analysis, rather than 'track feel'.   Again, the only way reality can make a suggestion, is a talented driver's (or group) direct comparison 'seat of the pants'.  Even then I think I'd still prefer to do that test myself, for a multitude of reasons!   :-)
v/r
pegler  

On a Lotus Europa, virtually the entire weight of the rear of the car hangs on four 5/16" bolts (two on each side of the car) in single-shear.

[ptegler]

less!     Only two lower shock bolts.    :-)    ptegler  

[IamScotticus]

On 2/18/2026 at 11:44 PM, ptegler said:

 

ptegler

There's a swag thread for this

Edited February 21 by IamScotticus