what's the policy for torquing con rod bolts?

[cookie]

haines says: 20Nm + 40° for an 80GS, R80R, R100GS, and R100R and 48 - 52Nm for all others.

isn't an R80G/S the same engine as an R80GS? it's the same bolts now anyway. does one use the later torquing with new bolts?

are they dry or oiled?

TIA

 

[(RIP) Kaister]

definitely oiled.

not sure which is right - but the best way is find the overall length increase required and ignore the torque value.

use a hand micrometer and a socket - no torque wrench required.




or just use 50Nm

 

[Smug]

Normally torque settings are done with the threads clean and not oiled.

 

[cookie]

i'm sure 50Nm will be fine.

can anyone who does this regularly, confirm that the bolts should be oiled. i know most torque values are dry, but end bolts often aren't and the bmw manuals do not say AFAICS

 

[Richard A]

My R80G/S BMW Reparaturanleitung from 1981 states 50 +/- 2 Nm for the con rod bolts.

There's no mention of oiled or not, but there is a sort of philosophical / mathematical treatise on screw pitches, tightening torque, stretch and DIN numbers at the beginning of the manual with associated tables (for those brainy German workshop mechanics with a Realschule pass in automotive engineering). Does anyone know offhand the material of and coating on these bolts, then I might be able to deduce whether it's considered to be correct to oil them or not?

To be honest, I'm thinking that it doesn't matter, otherwise there would probably be some info about degreasing the female threads in the bearing cap. As the advice is to coat everything liberally before assembly, oily is almost certainly the expected condition of the threads, notwithstanding the use of new bolts.

 

[cookie]

oily is almost certainly the expected condition of the threads, notwithstanding the use of new bolts.

that is my thinking too.

it is odd that it's not stated in the otherwise fairly comprehensive manuals though.

thanks for the input

 

[Beemerboff]

The difference in required torque between dry and oiled threads can be as much as a third, so on these critical fasteners it would be good to know for certain.

The system of 20 nm plus 40degres, or whatever would seem to reduce the margin for error.

Jim Cray should know- why doesn't someone phone him, or Rich Moore?

 

[cookie]

The difference in required torque between dry and oiled threads can be as much as a third, so on these critical fasteners it would be good to know for certain.

The system of 20 nm plus 40degres, or whatever would seem to reduce the margin for error.

Jim Cray should know- why doesn't someone phone him, or Rich Moore?

The problem with the angle method is that unless you have a jig to hold the con rod steady, there is quite large scope for error. I tried it, and it was pretty tricky.

I can tell you it produces a reading of approx 50nm on my torque wrench though.

 

[(RIP) Kaister]

Post2 top line

However every type of lube affects the torque applied - so light oil is the default or datum torque figure for all quoted torques unless stated

 

[Steptoe]

Oiled.

 

[duckspeed]

Get um reet tight I recon