Lotus Elan

Grade 8 failure?

PostPost by: lotuselan2 » Tue Sep 12, 2006 9:40 pm

Mike

But the MG clutch had the right price!



I remember about 20 years ago the Spanish gov't had some issue with the
Formula 1 teams and ask them to inventory every part and tool and give its
value. Lotus was the only team that knew what every bolt cost. Ferrari, on
the other extreme, did not have a clue what anything cost, "it doesn't
matter".



Ken

'69 Lotus Elan +2 with BDR

_____

From: ***@***.***lto:***@***.*** Behalf
Of Mike Causer
Sent: Tuesday, September 12, 2006 4:59 PM
To: ***@***.***
Cc: ***@***.***
Subject: Re: [LotusElan.net] Re: Grade 8 failure?



On Tue, 12 Sep 2006 21:24:15 +0100 Pete Taylor <[email protected]
<mailto:elansprint71%40btopenworld.com> btopenworld.com> wrote:

OK; Mechanical Engineer speaking; anybody on this forum ever had a
catastrophic failure of a suspension bolt (of any type)?

Engineer too (long ago): failures yes, could have been catastrophic.

The Austin-Healey Sprite (and its Austin A30/35 parent) has its front
suspension upright clamped to a threaded pin that runs in the lower
wishbone ("A-arm") Using a thread as a bearing means that the pin will
eventually see daylight. BTDTGTTS.

The Lotus Elite, Type 14, uses the rear drive-shaft ("axle-shaft" in USA?)
as the transverse locating member. It also suffers very badly from
vibration (due mainly to the 4,500rpm clutch from an MG fitted to a
7,500rpm engine). When the half-shaft bolts shake loose the handling
goes to pot -- and if you've any sense you promptly stop to find out
why. BTDTGTTS.

The Lotus Elite Type 74, and its sister the Eclat, has a highly loaded
bolt in the rear suspension that does break. Apparently this makes it a
bit squirelly but the suspension doesn't immediately come apart.

Mike
--
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'69 Lotus Elan +2 with Cosworth BDR
'84 Ferrari 400i
'94 Subaru SVX
'04 Audi allroad
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PostPost by: mikecauser » Tue Sep 12, 2006 10:26 pm

On Tue, 12 Sep 2006 22:22:51 +0100 Pete Taylor <***@***.***> wrote:

The Type 14 has Chapman strut (not possibly the best solution, and,
from what Robin Read wrote, not even designed by Chapman, rather by a
contact draffy!) whereas the Elan has a MacPherson strut, a much more
sensible design, given all the pushing and shoving involved.

Apart from the driveshaft taking the lateral load, there is not a lot of
qualitative difference between the Elan and the Elite. The Elite is
slightly better located fore & aft, the Elan doesn't put cornering
loads through the diff. The geometry is very similar.

The /original/ Chapman strut was copied from the Gogomobile (a couple of
years before Robin Read arrived at Lotus), but turned out to have
inadequate toe-in/out stiffness, hence the Series Two Elite suspension
and then the Elan. Interestingly the Europa and the Elite/Eclat went
back to putting the loads into the driveshaft again, so it can't have
been all bad. Well maybe it could, the heavily revised Eclat S3
(formally the Excel) went to unloaded driveshafts again.


Mike
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PostPost by: elansprint71 » Tue Sep 12, 2006 10:45 pm

Mike,
As you say, it seems that ACBC copied the Gogo arrangement, Robin Read
alludes him crawling under Roy Lee's Gogo and barely a week later
"inventing" the Chapman strut! He also says that a contactor produced
the design.
I have always found it hard to reconcile the lightweight rear
suspension of the Elan with the Brunelesque arrangement of the Europa.

Rgds,
Pete.


Mike Causer wrote:

On Tue, 12 Sep 2006 22:22:51 +0100 Pete Taylor
<***@***.*** <mailto:elansprint71%40btopenworld.com>>
wrote:

> The Type 14 has Chapman strut (not possibly the best solution, and,
> from what Robin Read wrote, not even designed by Chapman, rather by a
> contact draffy!) whereas the Elan has a MacPherson strut, a much more
> sensible design, given all the pushing and shoving involved.

Apart from the driveshaft taking the lateral load, there is not a lot of
qualitative difference between the Elan and the Elite. The Elite is
slightly better located fore & aft, the Elan doesn't put cornering
loads through the diff. The geometry is very similar.

The /original/ Chapman strut was copied from the Gogomobile (a couple of
years before Robin Read arrived at Lotus), but turned out to have
inadequate toe-in/out stiffness, hence the Series Two Elite suspension
and then the Elan. Interestingly the Europa and the Elite/Eclat went
back to putting the loads into the driveshaft again, so it can't have
been all bad. Well maybe it could, the heavily revised Eclat S3
(formally the Excel) went to unloaded driveshafts again.

Mike
--
Mike Causer Email - mailto:***@***.***
<mailto:mikec%40mikecauser.com>
GPG KeyID 1C2DDA07 WWW - http://www.mikecauser.com
<http://www.mikecauser.com>
Flood the fen again! - Wicken Fen enlargement -
http://www.wicken.org.uk <http://www.wicken.org.uk>


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PostPost by: rdssdi » Wed Sep 13, 2006 1:20 am

I am not entirely clear on the details but someone on this list had a front
suspension failure on an Elan +2.

Does anyone remember the details?

Bob
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PostPost by: mackmotorsport at aol.com » Wed Sep 13, 2006 2:29 am

AN hardware is not grade 8.It is more like grade 5 but tougher.
Bill Mack
mackmotorsport at aol.com
 

PostPost by: "Roger Sieling" » Wed Sep 13, 2006 1:03 pm

So Mike, if you're concerned about REAR drive-shaft failure, you must
have a 4-wheel drive Elite. HAH

I've had a catastrophic failure on my Eleven S2 (same Standard 10/
Triumph Herald upright as the Elan/ Europa/ 7) where one of the AN bolts
holding the steering arm failed. I watch these bolts carefully ever
since. Replaced w/ another AN bolt. Failure may have occurred due to
having to run different compound tires at Monterey Historics, which in
haste to get on the road for our week long tow to the west coast, were
changed just before we left and left unbalanced. They were far off and
then balanced at the track after one or two track sessions.

Roger


>> ***@***.*** 9/12/2006 4:59 PM >>>
On Tue, 12 Sep 2006 21:24:15 +0100 Pete Taylor

<***@***.***> wrote:

OK; Mechanical Engineer speaking; anybody on this forum ever had a
catastrophic failure of a suspension bolt (of any type)?

Engineer too (long ago): failures yes, could have been catastrophic.

The Austin-Healey Sprite (and its Austin A30/35 parent) has its front
suspension upright clamped to a threaded pin that runs in the lower
wishbone ("A-arm") Using a thread as a bearing means that the pin
will
eventually see daylight. BTDTGTTS.

The Lotus Elite, Type 14, uses the rear drive-shaft ("axle-shaft" in
USA?)
as the transverse locating member. It also suffers very badly from
vibration (due mainly to the 4,500rpm clutch from an MG fitted to a
7,500rpm engine). When the half-shaft bolts shake loose the handling
goes to pot -- and if you've any sense you promptly stop to find out
why. BTDTGTTS.

The Lotus Elite Type 74, and its sister the Eclat, has a highly loaded
bolt in the rear suspension that does break. Apparently this makes it
a
bit squirelly but the suspension doesn't immediately come apart.


Mike
--
Mike Causer Email -
mailto:***@***.***
GPG KeyID 1C2DDA07 WWW -
http://www.mikecauser.com
Flood the fen again! - Wicken Fen enlargement -
http://www.wicken.org.uk
"Roger Sieling"
 

PostPost by: denicholls2 » Wed Sep 13, 2006 10:11 pm

MIke wrote:

Interestingly the Europa and the Elite/Eclat went
back to putting the loads into the driveshaft again, so it can't have
been all bad. Well maybe it could, the heavily revised Eclat S3
(formally the Excel) went to unloaded driveshafts again.

-------------
While some blame the prevalence of rear hub bearing failures in the
Europa on this, I note that these failures occur almost exclusively in
the larger-tired TC's. My Type 54 is, I believe, still running an
unrestored original driveline and has not exhibited any unhappiness as a
result of this design. It sure does go around corners nicely, though.
:-)

-- Doug Nicholls, 54/1822 Ma~
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Posts: 587
Joined: 23 Jan 2006

PostPost by: "Sean Murray" » Tue Sep 19, 2006 5:10 pm

Pete,

Been away for 10 days in mainland Europe in the Plus 2, so late reply !

Many years ago, sheared an outer rotoflex bolt on a traffic lights redline start. The head of the bolt then caught the rear caliper, and cleaned the two alloy caliper mounting lugs right off the hub. Inspection of the broken bolt revealed 50% fatigue crack previous to failure.

Sean Murray

----- Original Message -----
From: Pete Taylor
To: ***@***.***
Sent: Tuesday, September 12, 2006 9:24 PM
Subject: Re: [LotusElan.net] Re: Grade 8 failure?


OK; Mechanical Engineer speaking; anybody on this forum ever had a
catastrophic failure of a suspension bolt (of any type)?

Waits as tumble-weeds pass by..................

Might be worth pointing out that a bolt is only threaded for part of its
length, the thing with a thread right up to the head is a called a
set-screw. They are useful for fixing corrugated metal roofing, etc.

Now, let's all try to think of something else to panic about. ;-)

Cheers,
Pete.

Gary Pighetti wrote:

> I would think that all those cool aircraft surplus web sites would
> drop the price a bit---if you don't count the ten hours you'll spend
> looking through all the stuff they have for sale.
>
> GP
>
> --- In ***@***.*** <mailto:lotuselan%40yahoogroups.com>,
> "Tebbutt, Bill" <[email protected]>
> wrote:
> However, you can order/pick up anything you need at
> > your local aircraft supply house, and the result is (expensive, yes)
> quite
> > elegant and trouble free.
> >
> > Just my two cents,
> > Cheers,
> > Bill Tebbutt
> >
>
>
"Sean Murray"
 

PostPost by: Guest » Tue Sep 19, 2006 11:03 pm

Pete

Funny you should ask this question. Just last Friday on my way to work
the lower wishbone/trunion bolt fell out in the process it ripped the
end of the wishbone and bent the anti-roll bar mounting bolt on the
bottom of the shock.

Now this was not actually a catastrophic failure of the bolt it was a
reminder that we should always replace Nylock (or similar) nuts with new
ones, not just reuse the old one again. I must admit that this nut had
probably been reused 4-5 times over the last 35 years and it only just
came off now.

I was very lucky not to do any further damage to the car or myself. I
had just negotiated a sweeping bend at about 80 kph with some traffic
around. It was the drivers side that collapsed so the car started to
veer to the wrong side of the road. I was still able to steer and
luckily there was a break in the traffic behind and to my left (OZ) and
I was able to pull over out of harms way.

I had noticed some looseness in the steering, but nothing major. I was
thinking to myself that I should check it out over the weekend, but as
it turned out that was too late.

Anyway back on the road with a new nut, repaired lower wishbone and a
rethreaded stud to mount the anti-roll bar.

Only damage to the body was some rubbing on the inner guard.

Rodney Stevens
CSIRO Minerals
phone 02 9710 6701
Mobile 0432 506 427
Web: http://www.minerals.csiro.au/

Personal Web Page
http://mywebpage.netscape.com/rodjohnst ... mepage.htm

----- Original Message -----
From: Pete Taylor
To: ***@***.***
Sent: Tuesday, September 12, 2006 9:24 PM
Subject: Re: [LotusElan.net] Re: Grade 8 failure?


OK; Mechanical Engineer speaking; anybody on this forum ever had a
catastrophic failure of a suspension bolt (of any type)?

Waits as tumble-weeds pass by..................

Might be worth pointing out that a bolt is only threaded for part of
its
length, the thing with a thread right up to the head is a called a
set-screw. They are useful for fixing corrugated metal roofing, etc.

Now, let's all try to think of something else to panic about. ;-)

Cheers,
Pete.
Guest
 
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