TR7 Flywheel Bolts

[Ecosse]

Hello All,

Could anyone please advise as to what thread the Flywheel to Crankshaft bolts are. The bolts on my engine are are 12-point so I need to purchase a socket to fit the bolts, my best guess is that the bolts are 7/16" UNF, could anyone confirm.

Thanks for any information.

Cliff

[BlueTR3A-5EKT]

Dolomite Sprint owners suggest the bolts have a 5/8” af bi hex head pattern.

 

https://forum.triumphdolomite.co.uk/viewtopic.php?t=22821

 

 

[Ecosse]

Hello Peter,

Thanks for that, and apologies for the delay in responding, I had a few other pressing matters to deal with, ie removing the cylinder head.

The flywheel bolt threads are 3/8" UNF and I found that a 14mm socket was the best fit on the 12-point flywheel bolts.

For info for anyone else removing a TR7 head. The five bolts did not cause any problems, nor did what I would call No.2 and No.4 studs. Nos. 1, 3 and 5 studs would not come out using the two nut method. I borrowed the TRR head removal tool, with the head sliding up of the remaining studs quite easily to discover that the studs had seized in the block. Nos.1 and 3 studs have now been removed, but No.5 stud is proving to be a challenge.

Cheers,

Cliff

[BlueTR3A-5EKT]

On 12/1/2023 at 10:07 AM, Ecosse said:

Hello Peter,

Thanks for that, and apologies for the delay in responding, I had a few other pressing matters to deal with, ie removing the cylinder head.

The flywheel bolt threads are 3/8" UNF and I found that a 14mm socket was the best fit on the 12-point flywheel bolts.

For info for anyone else removing a TR7 head. The five bolts did not cause any problems, nor did what I would call No.2 and No.4 studs. Nos. 1, 3 and 5 studs would not come out using the two nut method. I borrowed the TRR head removal tool, with the head sliding up of the remaining studs quite easily to discover that the studs had seized in the block. Nos.1 and 3 studs have now been removed, but No.5 stud is proving to be a challenge.

Cheers,

Cliff

14mm is close to 9/16” af.  
 

Have you tried to tighten the offending stud very slightly?   It may help.    It is the modern engine trick to give all the bolts a quick tightening ‘blat’ with the air gun before attempting to undo them.    That method certainly worked on my Rover 800 M16 cylinder head and Vauxhall 1.8 diesel cylinder head.

Edited December 2, 2023 by BlueTR3A-5EKT