Lotus Elan

Steering Rack Questions

PostPost by: gerrym » Tue Jan 27, 2009 8:25 am

Hi, does anyone know, can they measure the number of lock to lock turns for the Plus 2.

I'm reading the original sales brochure (copy on this website) with Mr Chapman stating the steering ratio is 2&1/2 turns lock to lock. "STEERING Rack and pinion, with telescopic, collapsible steering column. Optional right or left hand drive, 15 in. diameter dished steering wheel, 2 1/2 turns lock to lock". [/i]see Introductory Brochure
Surely the Triumph sourced rack for the 4 cyclinder cars was approximately 3&1/2 turns whilst the larger Triumph 6 cyclinder cars (eg TR5 was about 4).

Secondly, the drg in the manual section H with all the dimensions 1, 2, 3, 4, 5. Are these accurate?

Last, for the steering rack lock limiting spacers, can they just be machined up (as per drg in workshop manual) from steel, would brass or aluminium work just as well? How are they secured to the locknuts for the trackrods ends.

Regards

Gerry
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PostPost by: ppnelan » Tue Jan 27, 2009 10:00 am

This may help a little: www.lotuselan.net/forums/viewtopic.php?t=1445

From memory, the thin spacer is welded to the the locknut, and the tube at the other end is just loose on the rack.

I never did find out if +2 racks have different length spacers to the Elan ones...?

Will you use grease or oil in your rack :?: :wink:

:arrow: Matthew
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PostPost by: gerrym » Tue Jan 27, 2009 10:43 am

Matthew, thanks for reply and link.

I suspected that the sales brochure did not not correspond with reality. In addition at parking speeds the steering would be pretty heavy with a 2&1/2 turn ratio!!!.

For the spacers, I guess for the pinion end I could get machined a combined locknut spacer out of reasonably high strength steel, rather than welding to a locknut. It seems the other end could be made of any metallic material. My plan is to purchase a new Spitfire rack, strip it down, insert the locknuts and check the Chinese??? quality of the internals. Anybody have any recent good or bad experience on this.

To answer your question Matthew re lube, original advice from the workshop manual was to use grease via a nipple to be fitted into steering rack (at pinion) but I guess EP90 gear oil would provide better lubrication so long as the boots could be relied on to seal and not rot with exposure to oil.


Regards

Gerry
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PostPost by: andyelan » Tue Jan 27, 2009 1:02 pm

Hi Everyone

This could well have answered a question that's puzzled me for some time.

I could never understand why the steering on my Plus 2 should be lighter than that on my Europa Special in spite it being front engined and a heavier car. It never occured to me that the steering might have a different ratio. Visually, of course, the racks look identical.

I'll have to check this out.

Andy
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PostPost by: bcmc33 » Tue Jan 27, 2009 1:39 pm

I?ve recently refurbished two old S3 steering gears to fit one to my car with the intention of fitting 5.5? wheels.

The standard gear up to S4/Sprint was said to have a 5? movement, but I measured it at 4.75? with.

The gears did not have a spacer welded to the pinion end locknut (as shown in the Buckland book) and the loose spacers both measured 1.75? long. I never did understand why Lotus would have welded a spacer to the pinion end locknut as this would have been an unnecessary expense.

To reduce the gear movement to 4.375? to suit the 5.5? wheels I simply made a brass spacer to fit alongside the existing spacer which has resulted in 2? full turns lock-to-lock.

As far as I am aware, the +2 gear was a common part with the outer ball joint extensions.

FWIW I use fluid grease for the rack as I do for the trunnions as it addresses the lubricating limitations that affects both oil and grease in these types of applications. You can make your own, as I do, by mixing EP90 oil with a good quality lithium grease in a 30/70 ratio.
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PostPost by: ppnelan » Tue Jan 27, 2009 10:11 pm

bcmc33 wrote:I never did understand why Lotus would have welded a spacer to the pinion end locknut as this would have been an unnecessary expense.

Yes, Lotus wouldn't have done it if it hadn't been necessary... :lol:
Perhaps it was the only way to position the pinion/steering column laterally to miss the engine/chassis/etc and still get the same angle of turn in both directions... :?: :?

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PostPost by: Elanman99 » Tue Jan 27, 2009 10:24 pm

[quote="gerrym"]Matthew, thanks for reply and link.
My plan is to purchase a new Spitfire rack, strip it down, insert the locknuts and check the Chinese??? quality of the internals. Anybody have any recent good or bad experience on this.

Regards

Gerry[/quote]

I bought a brand new spitfire/herald/triumph replacement rack a couple of years ago intending to do exactly as you plan. Beware though! Whilst the rack I bought was externally identical the internal parts were not. In particular the inner ball joints were not threaded but were integrally swaged to the rack shaft and could not be dismantled.

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PostPost by: bcmc33 » Tue Jan 27, 2009 11:16 pm

Matthew,

We're obviously talking about a different car and installation.

The engine and chassis are nowhere near the operating ends of the gear.

The only reason Lotus reduced the gear travel was to prevent the inside of the front tyres fouling the stabiliser bar on full lock. (You have to remember the extremely small turning circle of the Spitfire to understand just how much of an angle the front wheels were on full lock.)

By putting the travel reduction spacers on one side only and centralising the gear before connecting the steering column achieves the same end.
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PostPost by: mikealdren » Wed Jan 28, 2009 9:07 am

Brian,
I'm sure you're right and this may also explain why some cars have tyres fouling their inner wheelarches and others don't. (see thread on tyre clearances).

Mike
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PostPost by: garyeanderson » Wed Jan 28, 2009 9:39 am

maybe later
Last edited by garyeanderson on Tue Aug 09, 2011 7:00 pm, edited 1 time in total.
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PostPost by: ppnelan » Wed Jan 28, 2009 10:30 am

bcmc33 wrote:We're obviously talking about a different car and installation.
The engine and chassis are nowhere near the operating ends of the gear.
...By putting the travel reduction spacers on one side only and centralising the gear before connecting the steering column achieves the same end.

No, we're talking about the same car... :lol:

The steering COLUMN lateral position is dictated by the gap between chassis & engine (bottom hose), which is fairly tight on an Elan. This determines the lateral position of the pinion shaft & rack BODY. Since the track rods are the same length, the RACK lateral position is determined by the proportion of spacers on each side. I know the TOTAL spacer thickness limits rack travel to avoid fouling, but having PART of the spacer on one side & PART on the other can only be for centralisation purposes. It must not be possible to locate the rack in the 'correct' as-designed (i.e. Triumph Herald) position on an Elan, hence the long spacer on one side, & short one on the other...

It WOULD probably be possible to centralise it with ALL the spacer thickness on one side only, but the track rod ends would not have the same thread engagement on each side which is not acceptable for an OE design. Why else would Lotus have bothered to add a 7mm spacer one end & 44mm one the other instead of a single 51mm one...

Can anyone else 'see' this :?: Or shall I go along with these 'men in white coats' now.... :P

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PostPost by: rgh0 » Wed Jan 28, 2009 12:20 pm

In the straight ahead steering position the rack itself is centralised on the Lotus just like it is on the Spitfire. This is required to get the steering geometry right

The body of the steering unit however is not central to allow for the location of the steering column on the Elan and the tight space it has to fit through versus its location in the Spitfire which was central.

The different size spacers in the Elan compensate for the offset body of the steering unit to limit the turn of the wheels on both sides to the same amount versus the roll bar and car body.


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PostPost by: Flatcap » Wed Jan 28, 2009 12:50 pm

Looking at the original question here. It should be remembered that there are two different pinions, from memory one has 6 teeth & one 7 teeth. Both can be fitted to the standard Elan / Triumph rack ( yes both will mesh with the same rack gear ). A starting point for any one should be to check which pinion they have in their rack. The spacers Lotus fitted are obviously to limit only the actual travel, the pinion changes the speed.
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PostPost by: ppnelan » Wed Jan 28, 2009 1:07 pm

rgh0 wrote:The different size spacers in the Elan compensate for the offset body of the steering unit to limit the turn of the wheels on both sides to the same amount versus the roll bar and car body.

:D Oh good! I was right! Makes a change... :wink:

Flatcap wrote:It should be remembered that there are two different pinions, from memory one has 6 teeth & one 7 teeth. Both can be fitted to the standard Elan / Triumph rack...

Interesting. Does this explain why the Elan & +2 both have the same limit spacers (assuming the Workshop Manual is correct) but have different turns lock-to-lock? Presumably the Elan has a 7 tooth pinion to get 2.6 turns, and the +2 has a 6 tooth pinion to get 3.5 turns. But the ratio of 6:7 doesn't match the ratio of 3.5:2.6... :?: :?

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PostPost by: andyelan » Wed Jan 28, 2009 1:30 pm

Hi Matthew

I've just done the same calculation.

2.6 turns with a 7 tooth pinion equates to 3.0 turns with a 6 tooth one. If the large pinion 8 teeth, however, then you would get 3.5 with the 6 tooth

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