Does any one know for sure if the flywheel bolts are torque-to-yield (one use) or ok to reuse if you use loctite?

 

The guidance I've hear is that if the torque values have a degree step, suck as 50Nm + 90 degrees, than they're TTY and need to be replaced. if that's the case, I wouldn't mess around with Loctite, it's not worth it to save <$10

 

Then how can ECSTuning and others sell flywheel bolts from APR that can be reused infinite times for the Cooper S automatic?

 

Hey Man, I don't know. It's different technology. Literally different materials. Maybe ARP uses something they feel can fulfill the fastening requirement but in a different way.

For the R56 head bolts as an example, the long OEM bolt is replaced with a long ARP stud that's fastened with a nut. Is it a better design? Maybe, I don't know. I just know I wouldn't re-use the stock bolt and use loctite to keep it in. If you replace with ARP, then follow their torque sequence. I'm sure that's acceptable, they have a great rep.

TTY bolts will actually change shape and that's what keeps them torqued, at least that's my understanding. When you "unscrew" them, you can feel a different resistance after the initial pull, then it changes consistency for the rest of the thread. So I'm pretty convinced there's a reason, but to answer your original question, I don't know why you couldn't do it with OEM bolt and loctite. I just wouldn't risk it if it meant I'd have to re-do 10 hours of work for a $10 part.

And as long as I'm ranting, my theory is that a lot of the timing issue you hear about on these cars are caused by re-used TTY bolts. They look exactly the same after they've been used. But if it didn't hold exactly the same, I don't think it's inconceivable that it could cause the timing to drift, and/or allow it to jump teeth.

 

I totally agree. Saving $20 on bolts isnt worth that risk if they are one-time use, but Mini more than other manufacturer whose cars I've owned is always recommending new fasteners when they may not be necessary.

I need to know specifically about the automatic transmission flexplate bolts.

 

The OEM flywheel bolts are TTY and should be replaced because they literally deform (elongate) to provide the clamping force needed. ARP probably makes their fasteners out of a stronger grade of steel that can handle that amount of stress without elongating.

 

oh boy....

 

I can't find anything on the flex plate bolts specifically but I would guess similar parts take similar hardware. Flexplate goes where the flywheel would go on a manual. Just replace them to be safe.

 

Try looking up the torque specs here --- https://www.newtis.info/tisv2/a/en/ --- if they're TTY or stretch bolts, it'll usually tell you to replace them.

 

I talked to a transmission specialist and he said the steel flexplate or flywheel bolts can be used 3 times max. The aluminum versions are one use only.

 

 

I totally agree that the ideal is to install new bolts given the difficult access. But let me be more explicit. Would you remove a transaxle just because someone used reused the same bolts?

 

 

Just to clarify a few things on this thread...

A "Torque-to-Yield" fastener, can use either a traditional torque-only clamping force measurement, or it can use a torque-plus-angle measurement. Torque-to-yield means exactly what the dictionary definitions of the individual words in the name mean. You are torquing the fastener to it's yield point. Where you have applied enough force to the material to permanently, plastically deform the fastener. It has nothing to do with how you measure the clamping force on the fastener.

The reason why many of us in the industry are moving to a torque plus angle measurement? Measuring turning torque on a fastener, is susceptible to variances in the measurement introduced by different variables, such as thread condition, thread cleanliness, any issues in between the clamped part and the cap of the bolt. This can cause what is known as "torque scatter" The lower torque values are not impervious to this, but, due to percentage, they are less pronounced. The angle measurement is impervious. Thus, when you turn the bolt to an angle, it results in a more reliable clamping force.

Now, I am not saying that torque plus angle does not introduce yield into a fastener. It does, in many diesel engines that use this torque measurement? You are required to measure bolts before, or during reusing them. For example, on some large diesel engines, you are required by the manufacturer to measure free length of the head bolts before reuse. On some engines, you are required to measure how far the connecting rod bolts stretch after torque is applied. But, all of these bolts are conditionally reusable, even though they are torqued using a torque plus angle measurement.

TLDR? You cannot rely on the torque measurement method to determine whether a fastener is reusable after removing torque from it. You have to rely on information from the manufacturer, or default to replacing any fastener that has been detorqued. (Source, 10 years as a field service technician, technical support agent, technical adviser and field service engineer with a major manufacturer)

To answer the OP's question? I just replaced the flywheel and clutch in my '11 MCS when I replaced the engine. All of the documentation that I found indicated the flywheel bolts are torque to yield, and not reusable.