Spyder chassis stiffener

[BennyD]

What are rivnuts?

 

[2b1ask1]

Rivnut; a threaded insert that works like a rivet but instead of a pin pulling it in it is pulled in by its own thread leaving a secured nut in place. They are not great as they often turn but variants are available including square holes so they cannot turn.

http://www.youtube.com/watch?v=P_uu_ba6qAM

 

[maverick]

Basically it's a nut which can be fixed into a sheet metal panal where there is no or limited access to the rear of panel or for quickness of insterlation , these are attached by men's of a special tool similar to a pop revit gun .it would take an age to explain how so I would google it .

 

[Grinzzz]

What are rivnuts?

Pain in the aris stupid yet brilliant idea. As the others have said, however once you tighten something up 1/1000th of a degree too much they become loose and you cant ever undo the item again!

Nah seriously if they're done right they're ok, I do however tend to belt and braces and spot around them with a little weld.

Havent seen square ones yet, Newton. Time to go shopping perhaps? Wonder if they still work with my lever tool?

 

[conaero]

As its structural, I will weld them in, there are only 4 after all and I have a lift.

 

[Tubber273]

Hmmmm...I'm watching this thread with interest!
I am curious, wat what point do you notice the "scuttle" or cowl shake?
Mine seems to appear almost exclusively at or very near 60mph (100kph?), and only on straight stretches.
When I round my favorite corner at this speed I get zero shake - solid as a rock through the corner then it comes back a bit.
My solution is simple.....increase speed!!

 

[Parisien]

....am sure someone will clarify the finer points of what it actually is, how to reduce it and if via this means reduce it even further..........typically if you put hand on dash as you go over a rough patch you will feel movement/vibration rather than said shaking


P

 

[2b1ask1]

Pain in the aris stupid yet brilliant idea. As the others have said, however once you tighten something up 1/1000th of a degree too much they become loose and you cant ever undo the item again!

Nah seriously if they're done right they're ok, I do however tend to belt and braces and spot around them with a little weld.

Havent seen square ones yet, Newton. Time to go shopping perhaps? Wonder if they still work with my lever tool?

Hi Grinzzz, basically in this day and age of laser cut profiles holes can be cut very acurately to any shape so square, star or hexagon threaded inserts are now commonplace in fabrication this is an example of a square one that should work with your tool: http://i01.i.aliimg.com/photo/v0/342448537/Square_Rivet_Nut.jpg

The advantage of a non-circular hole is reduced spinning and greatly improved reliability.

 

[Grinzzz]

I dont think I've got the kit in my garage to laser cut holes!!

 

[BennyD]

Hmmmm...I'm watching this thread with interest!
I am curious, wat what point do you notice the "scuttle" or cowl shake?
Mine seems to appear almost exclusively at or very near 60mph (100kph?), and only on straight stretches.
When I round my favorite corner at this speed I get zero shake - solid as a rock through the corner then it comes back a bit.
My solution is simple.....increase speed!!

Scuttle shake is generally dependent on road surface. If you go over rippled or rutted Tarmac you get the 'shake' coming through the car. If it happens on a straight, smooth road at a certain speed, it's more likely to be wheel imbalance. A lot of people regard scuttle shake as an insurmountable problem, I drive through it and accept it as a characteristic of the car.

 

[2b1ask1]

I think you could be right regarding wheel balance Benny, I particularly remember the old Honda CB's of the 70' & 80's before radial tyres used to suffer chronic 'tank slappers' between 60-70 both accelerating and braking but we mostly survived....

 

[Tubber273]

I thought about the possibility of a wheel imbalance in my case, but they were all balanced at the dealership last year when I got new Pirelli's.
Besides, if it were an imbalance, wouldn't the shake get worse at higher speeds?
Also...I had my baby up to just under 155mph last week and zero shake (true story). Solid as a rock. Weird or what???

 

[Grinzzz]

Harmonics. The vibration from unbalanced wheels sometimes does only show up at certain speeds. It'll be there all the time but damped by power steering and suspension. But at certain rpm at the wheel it'll hit the right/wrong frequency and become noticeable.

Dealer balances are always a bit suspect. A lot of dealers dont even have their own kit to do tyres anymore and sub the jobs out to a man with a van. Now while a man with a van can be almost as good as a full set up I would suspect most dealers go for lowest bidder in choosing their man.

Loads of useless tyre places out there, takes ages to find one with someone that cares.