engine and drivetrain Tip: Cheap Bolt Source

[bnam]

Actually the guibo flange location is one of the locations where there are shear forces acting -- when torque is transmitted through the coupling (in addition to the tensile on the bolt due to the tightened nut.  General design principle is that you don't want shear forces acting on threaded portions of bolts as the pointed bottom of the thread acts as a stress raiser.  

 

Note the shiny portion on the bottom portion of the shoulders -- that's from the sideways impact (shear) onto the flange.

 

 

 

See that portion sticking out is where the flange sits.  If the shoulder was shorter, the flange would sit completely on the threads.

 

[LarsAlpina]

Actually the guibo flange location is one of the locations where there are shear forces acting -- when torque is transmitted through the coupling (in addition to the tensile on the bolt due to the tightened nut.  General design principle is that you don't want shear forces acting on threaded portions of bolts as the pointed bottom of the thread acts as a stress raiser.  

 

Note the shiny portion on the bottom portion of the shoulders -- that's from the sideways impact (shear) onto the flange.

 

See that portion sticking out is where the flange sits.  If the shoulder was shorter, the flange would sit completely on the threads.

 

Well,

 

if you know better, buy expensive.

 

I´d say either the guibo was no longer OK, the screws didn´t sit tight enough or the surface around the holes of one flange was not even anymore while the things were still mounted in car. You shouldn´t see any marks on the bolts wether there is thread or not if everything is still allright. Do the test and demount flange screws on a car with an intact guibo that has been once mounted correctly with fully intact screws - you won´t see no marks like on your pictures.

 

In your case for some reason the flange was able to move in relation to its metal sleeves inside the guibo and that´s wrong. If a movement like this can happen - and only then - the shear forces you spoke about come into play. Normally on the guibo there should only be movement in the rubber parts that are located between the four bolts/sleeves from the driveshaft flange and the other four bolts/sleeves from the gearbox´s flange. And torque should be transmitted through that rubber parts only. None of the metal connections should be able to move a single bit once each of those is force-fit.

 

Regards, Lars.

Edited January 17, 2014 by LarsAlpina

[roadhog0]

Ive used hardware store 10.9 bolts a couple times for one or two. No issues. Put a nylock on and bam. Problem solved. I also save all my old guibo bolts from parts cars and re-use those. Nothing wrong with 95% of the ones that come off....

[HBChris]

I used to get my bolts from boltdepot.com when I lived on the East Coast. They have that same bolt for only $.68.

 

http://www.boltdepot.com/Product-Details.aspx?product=6753

I wish Bolt Depot had gold/yellow fasteners, Belmetric is pretty much it other than Eagleday but theirs are too bright.

http://www.eagleday.com/hexcapbolts.html

[peterschop]

I wish Bolt Depot had gold/yellow fasteners, Belmetric is pretty much it other than Eagleday but theirs are too bright.

http://www.eagleday.com/hexcapbolts.html

 

As for being too bright, after a good drive in real conditions, you will not be able to tell.

 

As for me, I went with McMaster-Carr and bought their Class 10.9 Black Finish Steel Hex Head Cap Screw M10 box of 10 for $6.71 along with their Metric Oval Lock w/ Conical Top Zinc-Plated Class 8 Steel locknut box of 25 for $5.42 to put on the other end.

[TobyB]

buying fasteners is a little scary these days.

 

Home Depot, etc, will not be 'first quality' fasteners.

Fine for little things, but I'm not sure I'd use them on a driveshaft

(even though Andrew's dead on- those Guibo bolts are very understressed)

 

McMaster, BelMetric, Grainger and only a few others are still reasonably trustworthy,

but even then, 'counterfeit' fasteners get into the parts stream.

 

Honestly, I tend to trust the stock fastener best unless it's been really munged up.

 

That's me.

 

t

[jgerock]

I had trouble finding metric hardware at Home Depot- the last time I went, a clerk told me they didn't sell enough to warrant stocking them. I have been visiting Lowe's and other small hardware stores.

[TobyB]

Ace Hardware, oddly, depending on the franchisee, has a pretty comprehensive selection.

It 'looks' good, and is a godsend for when you need 1 7x1mm bolt for a non- critical application.

 

Again, I would not trust them for something flight- rated...

 

t

[roadhog0]

Ace Hardware, oddly, depending on the franchisee, has a pretty comprehensive selection.

It 'looks' good, and is a godsend for when you need 1 7x1mm bolt for a non- critical application.

 

Again, I would not trust them for something flight- rated...

 

t

 

I did some minor metallurgy testing on Ace bolts (Grade 2, 5, 8, and metric 8.8. Were actually pretty nice bolts... But I didnt compare to anything else. I have plenty of faith in Ace fasteners. I've used them on many parts of my car. True Value also stocks a lot of the same fasteners. I know mine in town stocks the same stuff...

[LarsAlpina]

buying fasteners is a little scary these days.

 

+1 on that for Germany also.

 

If you go to one of our common Baumarkt (dict.cc says this is DIY superstore in english) they´re sometimes selling horrible chinese crap. I do only buy german-made in my specialized shop. Bit more $ to spend pay out in the end in quality and durability.

 

Regards, Lars.

Edited January 18, 2014 by LarsAlpina

[DaHose]

I am definitely a fan of Ace Hardware.  In my town, the two stores always carry a great selection of machine screws.

 

Jose

[TobyB]

Oh, but they are certainly not cheap!

 

Good to hear on the metallurgy- they 'look' and 'feel' good,

but that's not going to keep the lateral stabilizer on...

 

t

[bnam]

What's the torque spec on these bolts to the guibo and to the ones in the back to diff?  Getting set to reinstall.

[Hans]

check thread yesterday re"subframe" for link to torque sheets

[bnam]

Did find a reference (49-55lbft), but had difficulty finding the torque faq.  Will check the link you mention.  

Thx!

Edited January 19, 2014 by bnam