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Technical What's the damage? Panda 100hp

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Technical What's the damage? Panda 100hp

Stainless is easily available on eBay but DON'T USE STAINLESS bolts/screws.
(1) Its barely as strong as basic 8.8 material.
(2) It has very little spring so threads go suddenly tight and can shake loose all too easily.
(2) It WILL to cause electrolytic corrosion of the plain steel threads. See below
​

Zinc plating works because it has a higher anodic index at -1.25V so the zinc erodes before the steel.

From Wikipedia
Stainless steel Anodic index -0.5V
Iron and low carbon steel -0.85V
Difference of 0.35V is more than 2x acceptable for the harsh environment under a car body.

Harsh environments, such as outdoors, high humidity, and salt environments, there should be not more than 0.15 V difference in the anodic index.​
 
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DaveMcT said:
For new bolts etc go on eBay and buy what you need off the shelf.

DON'T get stainless as they wont have the necessary strength and can easily shake loose. Socket heads can be good (and usually high tensile) but slather them in anti seize to keep rust at bay.

For bump stops look at suppliers for poly bushes.

There's a 500 on eBay being broken. They might have the rear bump stops.
Click to expand...

Sorry to be negative, but the suspension bolts on modern cars are specifically desigined for the application,. While a standard bolt might be used for some positions, just specifiying a 30mm long M10 bolt is not enough for a critical application. Things that need to be considered are material strength (stronger may not be "better" in an assembly with pre-load), diameter, length, grip length, dimensional accuracy, thread type, thread class (and how it was made for some applications), protective finish, special features such as washer head, oversize shank, self locking etc. This may seem over the top, but is your (or perhaps the consequences of someone eleses) life worth the saving of cheap bolts. If you don't understand the joint design you can't be sure that a standard bolt is good enough.
There are also a lot of fake fastners out there. I know of one recent death due to machinery failure caused in part by a fastner that was miss marked for strength class. That nut was supplied by the equipment OEM and sourced by them from a reputable fastner supplier.

Robert G8RPI.
 
g8rpi said:
Sorry to be negative, but the suspension bolts on modern cars are specifically desigined for the application,. While a standard bolt might be used for some positions, just specifiying a 30mm long M10 bolt is not enough for a critical application. Things that need to be considered are material strength (stronger may not be "better" in an assembly with pre-load), diameter, length, grip length, dimensional accuracy, thread type, thread class (and how it was made for some applications), protective finish, special features such as washer head, oversize shank, self locking etc. This may seem over the top, but is your (or perhaps the consequences of someone eleses) life worth the saving of cheap bolts. If you don't understand the joint design you can't be sure that a standard bolt is good enough.
There are also a lot of fake fastners out there. I know of one recent death due to machinery failure caused in part by a fastner that was miss marked for strength class. That nut was supplied by the equipment OEM and sourced by them from a reputable fastner supplier.

Robert G8RPI.
Click to expand...

I take your pint but on the other hand cars are built to a price and huge amounts can be saved on fasteners.

On second thoughts eBay is not the best idea.

So go for OEM parts or a reputable supplier and where there is any doubt use high tensile. HT corrodes more than 8.8 steel but thats solved with lots of anti seize paste (which TBH should be used on all cars). For things like suspension mounting points just re use the old fasteners. They are unlikely to be rusty.

A friend of mine builds special motorbikes including round the world treckers that have to be uber tough and reliable. He uses a lot 8.8 galvanised but where there is any doubt he uses high tensile. All should be zinc plated because plain black (while cheap) will rust badly. Most of his stuff is socket headed.
 
g8rpi said:
Problem is how do you know the grade?
OEM fastners are not often marked with a strength grade. If a bolt IS clearly marked with a grade then it may be a standard part and candidate for replacement with a generic part of same sixe & grade.

Robert G8RPI.
Click to expand...

I understood the general rule was that if not marked, assume 8.8. Others should all be marked on the head.
 
portland_bill said:
I understood the general rule was that if not marked, assume 8.8. Others should all be marked on the head.
Click to expand...

For a standard bolt or nut, using an 8.8 in place of an unmarked one is normally OK, but there are at least 3 classes below 8.8 that are commonly marked (4.6, 4.8, 5.8). An unmarked bolt could be made from low grade mild steel.The two figures indicate the tensile and yield strengths respectively. Special bolts are not normally class marked because they should be replaced with the same part. Aircraft bolts have completely different markings.
A particular problem is using a bolt with the wrong shank or "grip" length (the unthreaded part). If too short the threaded section may be in shear or allow movement. If too long the thread can bottom out giving the impression the joint is tight when it's not.

Robert G8RPI.
 
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These HP turbine bolts are torqued up with a hydraulic wrench then heated with a heater rod dropped down the centre hole. When up to temperature, the nut is turned a specific angle and allowed to cool. In the old days of coal fired steam plants they were tightened with flogging spanners and sledge hammers then heated and angle tightened. Hammering made thread galling and stripped threads more likely. These will be 3" diameter studs. Imagine drilling one of those out !!!

Theses threads are wrapped for protection.

520004dd27eb9-26-06.jpg
 
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