Bonnet lifting at high speed...help!

Body, Paint, Interior and Trim questions and answers

Moderators: timk, Stu, zombie, Andrew, -alex, miata

matt9111
Fast Driver
Posts: 198
Joined: Mon Jun 23, 2008 9:56 am
Vehicle: NB8B
Location: Melbourne

Bonnet lifting at high speed...help!

Postby matt9111 » Mon Dec 07, 2009 7:07 pm

I took the 5 for a spin on the weekend and I've noticed that when I get above 130km/h the bonnet begins to lift at the front. When I'm doing around 200km/h there would be a gap of around 5-8cm at the front. Has anyone experienced this before? It's bothering me because I feel like the bonnet latch is going to let go and then who knows what will happen. I've been suggested bonnet pins, but I don't like the look of them so are there any other idea's?

I've wound down the rubber bonnet bushes to as low as they go, so the front of the bonnet is now sitting below the front bumper and it helped a little but still not enough for my liking.

Cheers

Matty
Great looking 02 BLACK NB8B, Tein S Tech Coils, Whiteline Adjustable Sways F&R, Carbing Alloy Rear Strut Brace ;)

User avatar
Hammer
Speed Racer
Posts: 2849
Joined: Fri Apr 25, 2003 11:00 am
Vehicle: NB SP
Location: Sydney
Contact:

Bonnet lifting at high speed...help!

Postby Hammer » Mon Dec 07, 2009 7:56 pm

I hope you weren't doing those sort of speed on public roads :?
H@mmer - 1994 Clubman | 2002 SP
Image
GO TOPLESS!!!

matt9111
Fast Driver
Posts: 198
Joined: Mon Jun 23, 2008 9:56 am
Vehicle: NB8B
Location: Melbourne

Bonnet lifting at high speed...help!

Postby matt9111 » Mon Dec 07, 2009 9:04 pm

No way, never want to hurt anyone
Great looking 02 BLACK NB8B, Tein S Tech Coils, Whiteline Adjustable Sways F&R, Carbing Alloy Rear Strut Brace ;)

User avatar
lowmiata
Racing Driver
Posts: 848
Joined: Thu Apr 24, 2003 11:00 am
Vehicle: ND - 2 GT
Location: gone fishin
Contact:

Bonnet lifting at high speed...help!

Postby lowmiata » Mon Dec 07, 2009 9:14 pm

Um.. if your bonnets lifting 5 to 8cm you'e got more than a slight problem!

or did you mean 5-8mm?

if its 5-8mm the next question would be how are you measuring it :shock:

anyway some panel deformation/lifting may occur at that speed the amount of air going into the front of the car needs to ge somewhere and not all of it will go down!

if it bothers you that much you can put a secondary retraint on it just a bit of chain with a snap lock hook or something similar, the bonnet lock you have from factory is a well designed(tried and tested) and for it to fail mechanically would mean something has gone wrong in the manufacture of it or someone has pulled it apart maybe and it has not gone back together properly

that being said if you have wound the bumpers down you probably now have a gap and the bonnet will chatter in the latch (causing a sensation that the bonnet is moving)

simple result? look past the bonnet or slow down? :P

seriously I wouldn't worry about it if your doing 200kph (in a controlled environment of course) there is other more important things you need to be focused on!
EVI15 1998 to 2008

Juffa
Racing Driver
Posts: 1751
Joined: Sun Apr 27, 2003 11:00 am
Vehicle: ND - 2 GT
Location: Bayside - Melbourne
Contact:

Bonnet lifting at high speed...help!

Postby Juffa » Tue Dec 08, 2009 12:48 pm

Not sure on the NB, but on the NA you can move the main hood catch up or down to reduce any movement. I would lower the catch to where the hood is sitting in line with the bumper and then raise the rubber buses so that the hood is held down onto the bushes by the catch, while still be aligned with the bumper. I know that the hood is locked down tight if the only way I can close it is by dropping it from 4 feet. Also, check the metal hook thingy on the hood that is grabbed and held onto by the catch. These can wear if there is excess movement and allow even more movement.

J
Former owner of Mailbu Stacey, Smurfette and Tweety.

User avatar
daffyflyer
Fast Driver
Posts: 457
Joined: Thu Dec 04, 2008 10:11 am
Vehicle: Clubman
Location: Caulfield
Contact:

Bonnet lifting at high speed...help!

Postby daffyflyer » Tue Dec 08, 2009 12:58 pm

good to make sure it stays down - the other MX5 at marulan last sunday had the bonnet flip up and bend itself over the windscreen :shock:

Had bonnet pins but no latch, looks like someone forgot to pin it


Dented the sh*t out of the bonnet, but was able to close after they punched it straight!
Developing a Car Industry Game - Visit www.automationgame.com
White 1994 MX5 Clubman - Carco Built NA Motor - 101kw ATW @ 7500rpm

rascal
Racing Driver
Posts: 1770
Joined: Fri May 16, 2008 1:39 pm
Vehicle: NB8A
Location: FarSE Melbourne

Bonnet lifting at high speed...help!

Postby rascal » Tue Dec 08, 2009 1:14 pm

matt9111 wrote: I've been suggested bonnet pins, but I don't like the look of them so are there any other idea's?


What about the flush mounted bonnet pins. (ala aerocatch) If colour matched to bonnet then they're not very noticeable at all..

User avatar
daffyflyer
Fast Driver
Posts: 457
Joined: Thu Dec 04, 2008 10:11 am
Vehicle: Clubman
Location: Caulfield
Contact:

Bonnet lifting at high speed...help!

Postby daffyflyer » Tue Dec 08, 2009 1:18 pm

Davex3 wrote:How are you managing to measure the gap and drive at the same time? :shock:

I think there is some serious macgyver sh*t going on here. :mrgreen:



Plastigauge?

A ruler on a stick?

A friend to climb out on the bonnet @ 200kph and measure? :P
Developing a Car Industry Game - Visit www.automationgame.com
White 1994 MX5 Clubman - Carco Built NA Motor - 101kw ATW @ 7500rpm

User avatar
Mr_Q
Racing Driver
Posts: 814
Joined: Tue Aug 10, 2004 4:41 pm
Vehicle: NB SE
Location: Sydney, Australia
Contact:

Bonnet lifting at high speed...help!

Postby Mr_Q » Tue Dec 08, 2009 2:24 pm

daffyflyer wrote:A friend to climb out on the bonnet @ 200kph and measure? :P

Never do that! The bonnet is aluminium and could dent. :P
Mister Q
Had: Red 2004 SE, Red 1993 NA8 Clubman, Green 1991 NA6 LE

Fatty
Speed Racer
Posts: 3175
Joined: Fri Feb 03, 2006 10:39 am
Vehicle: NA6
Location: Melbourne

Bonnet lifting at high speed...help!

Postby Fatty » Tue Dec 08, 2009 2:31 pm

Mr_Q wrote:
daffyflyer wrote:A friend to climb out on the bonnet @ 200kph and measure? :P

Never do that! The bonnet is aluminium and could dent. :P


:lol: :lol: :lol:

User avatar
hks_kansei
Speed Racer
Posts: 6154
Joined: Tue Feb 03, 2009 10:43 am
Vehicle: NB8A
Location: Victoria

Bonnet lifting at high speed...help!

Postby hks_kansei » Tue Dec 08, 2009 2:52 pm

Image

=

Image
1999 Mazda MX5 - 1989 Honda CT110 (for sale) - 1994 Mazda 626 wagon (GF's)

rascal
Racing Driver
Posts: 1770
Joined: Fri May 16, 2008 1:39 pm
Vehicle: NB8A
Location: FarSE Melbourne

Bonnet lifting at high speed...help!

Postby rascal » Tue Dec 08, 2009 4:10 pm

hks_kansei wrote:Image


An improvement on Chris Bangles designs..

User avatar
AJ
Speed Racer
Posts: 4349
Joined: Sun Oct 30, 2005 8:27 pm
Vehicle: NC
Location: Gold Coast

Bonnet lifting at high speed...help!

Postby AJ » Tue Dec 08, 2009 6:13 pm

I'm just impressed that someone found a straight stretch of road that is long enough for an old NB to actually hit 200....................does it parallel the Nullabor or something??? :lol: :mrgreen:
Image
Don't worry about what people think, they don't do it very often
XMX5 Rogues

User avatar
d-mag
Road Track Rally
Posts: 529
Joined: Fri Jun 27, 2008 9:34 am
Vehicle: ND - Turbo
Location: Melbourne

Bonnet lifting at high speed...help!

Postby d-mag » Tue Dec 08, 2009 6:15 pm

rascal wrote:
hks_kansei wrote:Image


An improvement on Chris Mangles designs..


Fixed. :D
MX5 Wanted. SE or NC (forced induction preferred :twisted: )

matt9111
Fast Driver
Posts: 198
Joined: Mon Jun 23, 2008 9:56 am
Vehicle: NB8B
Location: Melbourne

Bonnet lifting at high speed...help!

Postby matt9111 » Tue Dec 08, 2009 8:06 pm

Lol, I measured it with a ruler on a stick! I guesstimated it, but i'm a land surveyor so my estimation of distances is pretty because that's what i'm paid for.


Now anyways, I don't have any race tape and Safeway and Coles have sold out so im buggered, basically, lol.

Can I get like a two latch setup?

Cheers

Matty
Great looking 02 BLACK NB8B, Tein S Tech Coils, Whiteline Adjustable Sways F&R, Carbing Alloy Rear Strut Brace ;)


Return to “MX5 Body, Paint, Interior & Trim”

Who is online

Users browsing this forum: Google [Bot] and 281 guests