Lotus 7 - S4

[Mick O'Malley]

Hi Sonunet

S4 CARS frame number: Under the glassfibre body stamped into the transverse tube near where the seat belts are mounted.

Lots more info. here: www.lotus7register.co.uk

Regards, Mick

[richardl7S4]

Hi
My chassis no appears to be below the maker's plate as photo attached. It was a replacement chassis in the 80's and with the SPY prefix was perhaps made or repaired by Spyder Cars, who do the replacement Elan chassis ?

Richard

[anp]

Well at the end of a 4 Year battle I finally drove the S4 for its MOT yesterday it was freezing cold but driving the car made me smile It drove much better than the other one I had it passed just waiting fot the better weather !

[Mick O'Malley]

anp said:

Well at the end of a 4 Year battle I finally drove the S4 for its MOT yesterday it was freezing cold but driving the car made me smile It drove much better than the other one I had it passed just waiting fot the better weather !

Congratulations!

[richardl7S4]

Well done anp. Can we have a couple of photos of the finished job?

A few questions for you guys who know their way around the S4:-

My car was originally a GT but had a twin cam fitted in the 80's. The right engine mount is 20mm in front of the left to prevent the oil pump touching the steering column. The crank pulley finishes up about 10mm offset to the left. Is this normal, and will the propshaft UJ cope?

A main beam warning light is shown on the wiring diagram as an extra and is not shown on the dashboard layout. What is the normal position for this light?

The wiring loom would allow the resistor to fit inside or outside the bulkhead. Where should it be attached?

My heater motor is in a sad state. I've looked at Land Rover and Spitfire parts but can't see anything suitable. Problem is there are no markings, other than "Smiths".

What make and size of battery will fit the space and the original clamps?

I've read somewhere of a cable pull being used for opening the bonnet, but all I have is a lever attached to the bulkhead catch. Which is normal?

Where is the main engine earth strap positioned and what extra earth straps are recommended?

Where should extra line fuses be placed to reduce fire risk?

Sorry about the multiple questions!

Richard

[7s4whatelse]

Dear Richard,
to answer in short form: many S4s have been converted to TC specs as I see from my register.
Engine blocks (Kent vs. Lotus "L") have different widths. Engine mounts are symmetrical, but many owners have modified, because it is a very close job oil pump / steering column wise in RHD or exhaust pipes LHD. I have a drysumped RHD and have it even worse. Engine should be situated in mid position for several and importand reasons. Some owners have "misplaced" it to fit alternative exhaust systems. It will work far from ideal - the UJ will take this extra discomfort with a shorter lifespan. A good and standard looking position for a main beam control light would be approx 3 inch below the indicator light. Correct Smiths heater motors often show up at the big online auction platform. The origin is from a period Land Rover. You can even take an early Badgerum one. Battery wise go for one of the period Renault style batteries for perfect fit. Cable pulls were personal/individual adds. Connected to the pull lever. Main earth strap engine to the chassis is routed from one of the two top bolts (bellhouse / block) to the chassis, which has a weld on nut for this purpose. You can add an additional Lucas fuse holder close to the one existing to keep an original look as some S4 owners did.
Kind regards, Hajo

Edited by 7s4whatelse on Tuesday 5th April 07:28

[richardl7S4]

Hello Hajo,

Thanks for the response.

I did find a modified engine mount at Redline but this was only for the LHD twin cam. From what you say it would be better to get the engine as near central as possible, but I think the differential is also off-set on the back axle? Perhaps suspending the engine whilst adjusting for the optimum position is needed?

You didn't mention where the ballast resistor should be located?

The other answers will be very useful so thanks again for the advice.

Regards,

Richard

[7s4whatelse]

Hi Richard, - the location of the diff is "incorporated" in the design of the (very tight) propshaft tunnel. One day you will find out, that the passenger and driver seats are not mirrored and don´t have same size.....

As I said - there are several reasons for the engine to be centerline. But feel free to position it as you prefer. When driving alone you will have a better weight distribution and an easier corner weight set-up, when you position it more to the opposite side.... In 7Y style

Which resistor do you mean? One for a ballast ignition coil?

Cheers, Hajo

[richardl7S4]

Hi Hajo,

I've already found out about the different seat widths! Mine could not be re-covered without adding strength to the frame which made them slightly wider. They are now very tight and it will be a squeeze to get the belt fixings each side.

Yes, it's the Ballast Resistor for the coil that I need to position correctly. The wiring loom would allow for it to fit on the bulkhead near the solenoid, or just inside behind the instruments. I haven't seen one on photos of engine bays so assume it is out of sight.

Thanks again (until I think of something else), Richard

[7s4whatelse]

Richard - if I were you, I would place the ballast resistor near the solenoid. So it is easy acess for measurements in the case of a failure. Some S4s have coils without an external resistor. Mine doesn´t even have a regular coil. Example of a non centred engine in the 7Y:

Edited by 7s4whatelse on Tuesday 5th April 16:01

[richardl7S4]

Thanks again Hajo............until next time!

[anp]

This is the car on Sunday in the exact same spot I saw it in over 40 years ago ! if anyone needs photos of anything to help restoration please email me its dead original apart from the rear view mirror ! I doubt that without the help of some of the enthusiasts on this forum the car would not have been rebuilt Thank you

Edited by anp on Wednesday 6th April 16:18

[Mick O'Malley]

Yesterday I received in the post, courtesy of uglyduck (Ivan) the missing part for my S4 Seven project, a windscreen complete with extruded unobtanium frame.

Just a quick post to say a massive public 'thank you'. Top bloke

Mick

[7s4whatelse]

Mick, congrats for the windscreen! You definitely know what rare item you have in hand... A really rare find

[7s4whatelse]

@ANP: Great job. A beauty! "Back on the road" / Another one

[7s4whatelse]

@ Richard - regarding the engine positioning: For reference I had a look at the factory chassis drawings - there is no doubt that it is as I said before: symmetrical to centerline.

Edited by 7s4whatelse on Saturday 9th April 08:33

[7s4whatelse]

Windscreen pillars


Someone contacted me, but I lost the email. Still for sale: one set of unused, undrilled pillars.

[richardl7S4]

Thanks for checking re the engine alignment Hajo.

With the engine in it's present position I only have about 5mm clearance between engine mount and column, with 10mm between oil pump and column. I wonder if Lotus actually kept to the drawing as you do hear stories of corners being cut? Redline only have a cranked left hand engine mount for LHD cars but I suppose one could be made up for mine. I'm not aware of a lower profile oil pump being available.

If the engine should be symmetrical in the front, then the gearbox should also be central. My gearbox appears to sit correctly on it's mountings but must be at least 20mm off-set at the tail. Am I correct in thinking the differential pinion is off-set to the right?

Does anyone on this forum have a twin-cam installed, either as original equipment or swapped-in later like mine? Can you check if the engine is central to the chassis and what clearance there is around the steering column.

Thanks,

Richard

[7s4whatelse]

Richard, - the engine in our seven is a VERY tight fit- in both cases Kent or Twin Cam. You even get more problems when the engine rubber mounts are aged and have seen oil and got soft. As long as the engine height is correct, you can modify or fabricate an engine mount individually, as there is much room to place the rubber mount on the chassis bottom. You just need to drill 2 new holes. Also Lotus and early Caterham mounts can be used / modified to suit. The gearbox tail position is defined by the chassis crossmember and its mounting.
Think also about the hoses and especially the exhaust (collector, primaries) which will not forgive an "angled" engine without reacting.
Try to send a photo of the "collision point", here or PM me



"standard" mount and rubber damper. Note: there is an additional safety shield which is added not shown here

Edited by 7s4whatelse on Sunday 10th April 13:04

[uglyduck]

I have stripped the front suspension on my 7S4 and found some issues that will require some attention. my biggest issue is that I cant find any technical drawings of the front suspension pickup points. Does anyone have chassis drawings?