Lotus Elan

Grade 8 failure?

PostPost by: rdssdi » Tue Sep 12, 2006 2:01 pm

"Beware! A grade 8
(theoretically stronger) bolt is much more brittle (susceptible to
shattering under sudden pothole shock) than a lowly Grade 5"

That's interesting. I replaced all my front vertical link bolts with AN
Grade 8. I also replaced the stub axle retaining nut with an AN grade 8.

Should I remove all the Grade 8 hardware and substitute Grade 5?

Bob
1969 Elan +2
rdssdi
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1419
Joined: 30 Sep 2003

PostPost by: s2lola » Tue Sep 12, 2006 2:30 pm

Let's move directly into overkill (as I have done with my own Elan project)
and use nothing but aircraft hardware!!!!!!

While I'm not qualified from an engineering persepctive to opine (that won't
stop me), in my opinion the single biggest issue with automotive fastener
failure (other than incorrect torque) is threaded portions of bolts within
their respective "bore holes". Aside from acting like many tiny chainsaws
inside the bore, in shear there are threads (stress risers) in the bridge
between the 2 fastened parts - I have to believe this is a recipe for
disaster.

I don't think it is practical to source enough non-aircraft HW with the
required unthreaded shoulders on all of the bolts of different dimensions to
put the cars together. 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

-----Original Message-----
From: ***@***.***lto:***@***.*** Behalf
Of ***@***.***
Sent: 2006/09/12 09:50
To: ***@***.***
Subject: Re: [LotusElan.net] Re: Grade 8 failure?


"Beware! A grade 8
(theoretically stronger) bolt is much more brittle (susceptible to
shattering under sudden pothole shock) than a lowly Grade 5"

That's interesting. I replaced all my front vertical link bolts with AN
Grade 8. I also replaced the stub axle retaining nut with an AN grade 8.

Should I remove all the Grade 8 hardware and substitute Grade 5?

Bob
1969 Elan +2
s2lola
Third Gear
Third Gear
 
Posts: 260
Joined: 16 Jan 2004
Location: Toronto, Ontario

PostPost by: "Roger Sieling" » Tue Sep 12, 2006 2:37 pm

Bob,

What do you mean "AN grade 8"? What are the markings on the bolt heads?
They will be either AN or Gr8, but they are not the same. As Doug just
mentioned, Gr5 is less brittle than Gr8 and if you look at the actual
ratings of AN bolts, they are more in line w/ Gr5. The advantage of
using AN bolts is that the lengths are based on "grip" length and all
length bolts of the same diameter have the same threaded length. The
length from under the head to the end of thread (the smooth unthreaded
portion) will vary and that is the grip length. So, you can have nice
unthreaded bolts within the joint which fit the holes better and don't
act like files wearing the hole bigger, and also have just the right
amount of thread to install a nut and washer. But this also means that
you have to size each bolted joint for exact length.
The only way to do a race car!!!

Roger

>> ***@***.*** 9/12/2006 9:49 AM >>>
"Beware! A grade 8

(theoretically stronger) bolt is much more brittle (susceptible to
shattering under sudden pothole shock) than a lowly Grade 5"

That's interesting. I replaced all my front vertical link bolts with AN

Grade 8. I also replaced the stub axle retaining nut with an AN grade
8.

Should I remove all the Grade 8 hardware and substitute Grade 5?

Bob
1969 Elan +2
"Roger Sieling"
 

PostPost by: lotuselan2 » Tue Sep 12, 2006 2:50 pm

Here is my understanding of Grade 8 and Grade 5 bolts. Grade 8's are high
tensile but brittle and less good in shear applications. Grade 5's are
lower tensile strength but more ductile strength, so they are better in
shear. How does this relate to our cars? Most suspension bolts and those
rubber donut bolts are better in Grade 5. Head bolts, rod bolts and such
are better in Grade 8. I'm an engineer but not mechanical, so if a true
expert wants to give the real story then have at it. Above rational has
worked for me for a long time.



Ken

'69 Lotus Elan +2 with BDR

_____

From: ***@***.***lto:***@***.*** Behalf
Of ***@***.***
Sent: Tuesday, September 12, 2006 9:50 AM
To: ***@***.***
Subject: Re: [LotusElan.net] Re: Grade 8 failure?



"Beware! A grade 8
(theoretically stronger) bolt is much more brittle (susceptible to
shattering under sudden pothole shock) than a lowly Grade 5"

That's interesting. I replaced all my front vertical link bolts with AN
Grade 8. I also replaced the stub axle retaining nut with an AN grade 8.

Should I remove all the Grade 8 hardware and substitute Grade 5?

Bob
1969 Elan +2
'69 Lotus Elan +2 with Cosworth BDR
'84 Ferrari 400i
'94 Subaru SVX
'04 Audi allroad
lotuselan2
Third Gear
Third Gear
 
Posts: 377
Joined: 19 Oct 2005
Location: Shamong, NJ

PostPost by: Tintin » Tue Sep 12, 2006 3:19 pm

Here is my understanding of Grade 8 and Grade 5 bolts. Grade 8's
are high tensile but brittle and less good in shear applications.
Grade 5's are lower tensile strength but more ductile strength, so
they are

better in shear. How does this relate to our cars?

Well, theoretically bolts should not be used in shear (except
for dowel bolts of course). The lateral forces are transfered into
axial ones by the friction of the contact area. At least
this is how a bolt is calculated in a flange design process.
However some bolts in a Lotus (Spit) suspension clearly don't
follow this route so more ductility is quite a good idea IMHO.




Tim
--
1964 Norton Atlas - 1974 Lotus 130/5
Parts falling of these vehicles are of the
finest british craftsmenship
Tintin
Second Gear
Second Gear
 
Posts: 59
Joined: 11 Jul 2006
Location: Germany

PostPost by: "Benjamin Levy" » Tue Sep 12, 2006 3:34 pm

On 9/12/06, Roger Sieling <***@***.***> wrote:

What do you mean "AN grade 8"? What are the markings on the bolt heads?
They will be either AN or Gr8, but they are not the same.

For standard grade 8 vs grade 5 markings, take a look at:
http://www.boltdepot.com/fastener-infor ... Chart.aspx

For more info about bolts, Carroll Smith wrote a great book called
"Nuts, Bolts, Fasteners and Plumbing Handbook".
---Ben
"Benjamin Levy"
 

PostPost by: rdssdi » Tue Sep 12, 2006 3:36 pm

I am using Grade 8, not AN. Most are Lake Erie or equivalent.

To replace wit Grade 5, that remains the question.

Bob
rdssdi
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1419
Joined: 30 Sep 2003

PostPost by: lotuselan2 » Tue Sep 12, 2006 4:55 pm

My recommendation is Grade 5 for suspension bolts in shear, which is most of
them.



Ken

'69 Lotus Elan +2 with BDR

_____

From: ***@***.***lto:***@***.*** Behalf
Of ***@***.***
Sent: Tuesday, September 12, 2006 11:22 AM
To: ***@***.***
Subject: Re: [LotusElan.net] Re: Grade 8 failure?



I am using Grade 8, not AN. Most are Lake Erie or equivalent.

To replace wit Grade 5, that remains the question.

Bob
'69 Lotus Elan +2 with Cosworth BDR
'84 Ferrari 400i
'94 Subaru SVX
'04 Audi allroad
lotuselan2
Third Gear
Third Gear
 
Posts: 377
Joined: 19 Oct 2005
Location: Shamong, NJ

PostPost by: lotuselan2 » Tue Sep 12, 2006 6:02 pm

Aircraft Hardware? That's NOT overkill. The motorcycle racers go for
titanium bolt kits for the suspension that cost over $1500 for a 250 2-stoke
GP bike. How many bolts can a bike like that have? There are a few large
ones for axles and swing arm but still there are not many. Now, that IS
overkill. I diet for the rider is a cheaper weight savings.



Ken

'69 Lotus Elan +2 with BDR

_____

From: ***@***.***lto:***@***.*** Behalf
Of Tebbutt, Bill
Sent: Tuesday, September 12, 2006 10:27 AM
To: '***@***.***'
Subject: RE: [LotusElan.net] Re: Grade 8 failure?



Let's move directly into overkill (as I have done with my own Elan project)
and use nothing but aircraft hardware!!!!!!

While I'm not qualified from an engineering persepctive to opine (that won't
stop me), in my opinion the single biggest issue with automotive fastener
failure (other than incorrect torque) is threaded portions of bolts within
their respective "bore holes". Aside from acting like many tiny chainsaws
inside the bore, in shear there are threads (stress risers) in the bridge
between the 2 fastened parts - I have to believe this is a recipe for
disaster.

I don't think it is practical to source enough non-aircraft HW with the
required unthreaded shoulders on all of the bolts of different dimensions to
put the cars together. 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

-----Original Message-----
From: ***@***.*** <mailto:lotuselan%40yahoogroups.com> ps.com
[mailto:***@***.*** <mailto:lotuselan%40yahoogroups.com> ps.com] On
Behalf
Of ***@***.*** <mailto:RDSSDi%40AOL.COM>
Sent: 2006/09/12 09:50
To: ***@***.*** <mailto:lotuselan%40yahoogroups.com> ps.com
Subject: Re: [LotusElan.net] Re: Grade 8 failure?

"Beware! A grade 8
(theoretically stronger) bolt is much more brittle (susceptible to
shattering under sudden pothole shock) than a lowly Grade 5"

That's interesting. I replaced all my front vertical link bolts with AN
Grade 8. I also replaced the stub axle retaining nut with an AN grade 8.

Should I remove all the Grade 8 hardware and substitute Grade 5?

Bob
1969 Elan +2




http://www.LotusEla <> n.net
'69 Lotus Elan +2 with Cosworth BDR
'84 Ferrari 400i
'94 Subaru SVX
'04 Audi allroad
lotuselan2
Third Gear
Third Gear
 
Posts: 377
Joined: 19 Oct 2005
Location: Shamong, NJ

PostPost by: denicholls2 » Tue Sep 12, 2006 6:48 pm

Carroll's book, referenced below by Ben and sold as a part of the "To
Win" series, will answer all of your questions in this thread with
logical, easy to understand explanations and diagrams. One very
revealing thing his examples do is show that people who should pay
better attention to basic engineering principles in using fasteners
(read designers) often don't. His discussion of rivets was a great
example of this, stress risers another.



The conclusion of other discussions like this has been that AN is fine
but is overkill. Grade 8 is probably OK but you'd have been better off
saving the cash and getting Grade 5. And yes, threading where the nut
doesn't go is a big no-no. Fortunately good supplies of AN bolts are
available if you're willing to pay for them, and there aren't enough
suspension bolts in an Elan to break most of our piggy banks.



My personal opinion would be that a car driven hard should not have
Grade 8 bolts in its suspension. But that is a personal opinion, not a
technical one. Others can demonstrate that Grade 8 should be adequate
for the shear loads typically seen at least in road use, so I'm not
looking to start an argument, just suggesting what I believe to be the
best approach.



- Doug Nicholls, 54/1822 Ma~



Posted by: "Benjamin Levy" ***@***.***
<mailto:***@***.***ect=%20Re%3A%20Grade%208%20failure%3F>
deguspice <http://profiles.yahoo.com/deguspice>

Tue Sep 12, 2006 8:34 am (PST)

On 9/12/06, Roger Sieling <***@***.***
<mailto:rogsie%40telesistech.com> > wrote:

What do you mean "AN grade 8"? What are the markings on the bolt
heads?

They will be either AN or Gr8, but they are not the same.

For standard grade 8 vs grade 5 markings, take a look at:
http://www.boltdepot.com/fastener-infor ... Chart.aspx
<http://www.boltdepot.com/fastener-information/Bolt-Grade-Chart.aspx>

For more info about bolts, Carroll Smith wrote a great book called
"Nuts, Bolts, Fasteners and Plumbing Handbook".
---Ben
denicholls2
Fourth Gear
Fourth Gear
 
Posts: 587
Joined: 23 Jan 2006

PostPost by: Garibaldi » Tue Sep 12, 2006 7:06 pm

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 ***@***.***, "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

Garibaldi
First Gear
First Gear
 
Posts: 40
Joined: 24 Jul 2006
Location: Falmouth Maine

PostPost by: elansprint71 » Tue Sep 12, 2006 8:31 pm

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
>


elansprint71
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 4092
Joined: 16 Sep 2003
Location: Cheshire, UK.

PostPost by: "Benjamin Levy" » Tue Sep 12, 2006 8:56 pm

On 9/12/06, Nicholls, Doug <***@***.***> wrote:
Carroll's book, referenced below by Ben and sold as a part of the "To
Win" series, will answer all of your questions in this thread with
logical, easy to understand explanations and diagrams.

> For more info about bolts, Carroll Smith wrote a great book called
> "Nuts, Bolts, Fasteners and Plumbing Handbook".
> ---Ben

According to rumor, in keeping with the "Drive To Win", "Drive to
Win", .. series, Carroll Smith wanted to name the book "Screw To Win".

Someone (I wish I could remember who) gave me a large sticker to go
over the title of "Nuts, Bolts, Fasteners and Plumbing Handbook" that
said "Screw To Win".
---Ben
"Benjamin Levy"
 

PostPost by: mikecauser » Tue Sep 12, 2006 9:04 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
mikecauser
Second Gear
Second Gear
 
Posts: 107
Joined: 15 Jun 2005

PostPost by: elansprint71 » Tue Sep 12, 2006 9:28 pm

Yes Mike, but we are talking about the Elan, I think.
:-\

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.

Cheers,
Pete.

Mike Causer wrote:

On Tue, 12 Sep 2006 21:24:15 +0100 Pete Taylor
<***@***.*** <mailto:elansprint71%40btopenworld.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
--
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>


elansprint71
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 4092
Joined: 16 Sep 2003
Location: Cheshire, UK.
Next

Total Online:

Users browsing this forum: No registered users and 21 guests