XU 8V Group A Cylinder Head Bolt Tightening Method

[LucasDunkley 0]

Hi all,

 

I’m well aware I’m probably opening up a can of worms but I currently in the process of refitting my ‘new’ cylinder head to my car.

 

It’s a D6B XU9 using the later style T55 torx head bolts.

 

Doing some research, I’m surprised by the number of different recommendations regarding torque values.

 

The Haynes manual suggests a torque value and a 300deg angle tighten, as I’m sure many of you already know.

 

Interestingly, I found in the 1900 Group A build manual, it suggests a staged torque of (approximate values here as I’ve converted from kgm to Nm) 20,40,60 and 80Nm. This doesn’t seem like a great deal of torque when compared to the Haynes method and other methods that list up to 75ft lbs (~102Nm).

 

Has anyone successfully used this method? Or have I missed something glaringly obvious when translating from French?

 

Thanks

Lucas

 

[petert 614]

Do yourself a favour and buy some studs. I bought these from Pug1off. They were smooth and predictable. 80Nm stays under the yield point of the material, making them re-usable. 102Nm would be past the yield point.

 

Edited May 15 by petert

[Gohn 71]

they look good

better than the one use OE bolts

 

be interested to get a set for the XUD7T if there are suitable ones available

the GTi has M11 bolts and the XUD's take M12

[Tom Fenton 1,562]

On 5/14/2025 at 10:45 PM, LucasDunkley said:

Hi all,

 

I’m well aware I’m probably opening up a can of worms but I currently in the process of refitting my ‘new’ cylinder head to my car.

 

It’s a D6B XU9 using the later style T55 torx head bolts.

 

Doing some research, I’m surprised by the number of different recommendations regarding torque values.

 

The Haynes manual suggests a torque value and a 300deg angle tighten, as I’m sure many of you already know.

 

Interestingly, I found in the 1900 Group A build manual, it suggests a staged torque of (approximate values here as I’ve converted from kgm to Nm) 20,40,60 and 80Nm. This doesn’t seem like a great deal of torque when compared to the Haynes method and other methods that list up to 75ft lbs (~102Nm).

 

Has anyone successfully used this method? Or have I missed something glaringly obvious when translating from French?

 

Thanks

Lucas

 

Be careful, the early XU had hex head bolts that were not a stretch bolt and could be re used. I would not be surprised if that is what the old Gp A manual is talking about given the time period in which it was probably written.

 

When using the stretch bolts, I have always used the Haynes method, although I do the angle tightening bit in three stages, working round in the usual order from the middle out. Maybe not into the hundreds but I have done a lot of XU head gaskets this way and no issues.

[SRDT 199]

The Gr.A manual that i have is from 87-88 and the torque is also 2, 4, 6 then 8 mKg but there is a bit more to it because once y'oure at 8 mKg you also need to let the engine heat up then cool down before loosening each bolt and set it back to 8 mKg. You also must use tallow as a lubricant for the bolts, no substitute.

 

Another interesting part is that the gasket isn't a stock one and that can alter the torque spec. In the manual you can also use a "type 205 turbo 16" metallic silicone gasket with extra liner protrusion but then the 4 outermost bolts must be set to 7 mKg.