Prop Shaft Bolts

[johnhetherington]

Does anyone know what grade the 4 bolts that connect the propshat to the diff need to be, is 8.8 OK or do they need to be stronger.

I took my prop off and lost the bolts, long story, so need to get some more.

Thanks

John

 

http://www.johnskitcar.com

[Redspec]

10.9

 

http://www.ebay.co.uk/itm/New-Propshaft-Bolts-Escort-Mk2-Capri-Sierra-Granada-/150613205455?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item23113f21cf

 

 

[Guest sandy77uk]

thats a *bleep*er, ive just used 8.8 on mine

[johnhetherington]

10.9

 

http://www.ebay.co.uk/itm/New-Propshaft-Bolts-Escort-Mk2-Capri-Sierra-Granada-/150613205455?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item23113f21cf

 

Cheers that's great, will get some ordered, by the way just for the record mine are M10x1.5

[Shaft]

I got slightly longer than required also, they thread into the diff driveflange then I used Nylock nuts as well to ensure they stay tight and firm, lock nuts if you like.

[Guest sandy77uk]

surely the torque from a zetec isnt enough to sheer 4 8.8 high tensile bolts? mine are tightened with nylock nuts

[Shaft]

surely the torque from a zetec isnt enough to sheer 4 8.8 high tensile bolts? mine are tightened with nylock nuts

 

Fully agree Sandy..... Not a chance of a car engine sheering them at 8.8.

[Longboarder]

Surprised at the confidence in 8.8 bolts. One of a tuned pintos tricks is to shear the flywheel bolts and there are six of them. I would advise sticking with the 10.9 bolts which also are a metric fine thread I think.

 

Nigel

[Shaft]

Surprised at the confidence in 8.8 bolts. One of a tuned pintos tricks is to shear the flywheel bolts and there are six of them. I would advise sticking with the 10.9 bolts which also are a metric fine thread I think.

 

Nigel

 

I've always run 8.8s on the props on my Landrover race motor... never had a problem with them to be honest and they where getting 330bhp & 285Lbft thrown at them. Broken plenty of half shafts and stripped a few crown wheels whilst being over exhuberant on the throttle, but never sheared the prop bolts.

 

Could well be shear luck (no pun intended), and i'm not saying your wrong Nigel, just that I've been ok in the past.

 

Best advice i suppose is go for the 10.9's and play safe.

 

Nick.

[Grim]

The higher the grade of bolt, the higher the allowable tightening torque, and the higher the clamping force.

The strength of the joint is gained by the friction between the two flanges under the clamping force, and not the shear strength of the bolt.

 

It's normal to tighten a fastener to about 80% of its yield strength. If you tighten an 8.8 bolt to the torque in the haynes manual for a 10.9 bolt, you will probably reach 100% of its yield strength, ie you're permanently plasticly deforming the bolt. Too much and you'll knacker the threads in the prop flange and weaken the bolt.

 

You can use 8.8 bolts to a lower torque figure, as long as the corresponding reduction in clamping force does not cause any movement of the flanges, which would eventually cause the bolts to fail. Is that likely? maybe not? is it worth risking it, when the prop is spinning at up to 3000rpm beside your legs and lower body? Probably not, for the price of a few bolts.

 

Also, if you've gone to the effort of finding 8.8 grade metric fine bolts, why not just buy the 10.9?

[fry61]

There is only one question to answer -- why did Mr Ford fit 10/9 if 8/8 would do the job?

[Guest sandy77uk]

I got all my nuts and bolts from a mate who works as a heavy plant mechanic

 

Florin, everything about fords is massively over engineered, look at the nightmare gearstick assembly on the mt75

 

If this is so critical how come mine passed iva with 8.8? And more to the point why isnt it an essential item in the iva like the bolts used on seat belt anchor points?

[Guest mower man]

Whilst the IVA gremlins test or inspect a lot of things some of which are irellavant or just plain bl--dy stupid I would not have thought they would be inspecting induvid bolts for spec but for my own peice of mind bolts in the positions of high stress i.e. caliper bolts ,prop bolts I would replace with either oem spec or one higher but never one lower ,if you have ever seen what mayhem a detached prop can do I think you would agree Safety First not F--k it it will be ok---- mower man

[Guest Spencer Griffiths]

Can't agree more, don't mess around trying to figure out what might do, get the correct ones. I got mine from Burton Power because I trust them and they are local to me £1.21 each.

http://www.burtonpower.com/6118344.html

I also fitted the ARP Pro bolts on the flywheel with the correct grease so they torque up to the correct setting. I really don't want either a flywheel or propshaft coming loose or failing just so I can save a few quid.

[fry61]

 

 

Florin, everything about fords is massively over engineered, look at the nightmare gearstick assembly on the mt75

 

 

Fair enough;but you only know its under engineered after it's broken;& I would never be able to build an aircraft -- it would be too heavy to lift off.