Pressed piston pins..Removal?
08-21-2003, 12:17 PM
#3
Le Mans Master
Re: Pressed piston pins..Removal? (Fevre)
There are special tools for the job.
Different diameter arbors and cradles to hold the piston correctly to avoid distorting it.
The cradles are designed to hold the piston without damaging the casting where the wrist pin goes through. It's not a "one size fits all" situation.
And as posted... you should use a press.
Even with the correct tools, pistons can be easily damaged either when pressing out the pins, or pressing in the pins. Typically, there are radii that interfere with the proper support of the tooling, and you have to make judgement calls on the fly. Experience is the key.
Tom
Different diameter arbors and cradles to hold the piston correctly to avoid distorting it.
The cradles are designed to hold the piston without damaging the casting where the wrist pin goes through. It's not a "one size fits all" situation.
And as posted... you should use a press.
Even with the correct tools, pistons can be easily damaged either when pressing out the pins, or pressing in the pins. Typically, there are radii that interfere with the proper support of the tooling, and you have to make judgement calls on the fly. Experience is the key.
Tom
08-21-2003, 12:20 PM
#4
Race Director
Member Since: Mar 2001
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Re: Pressed piston pins..Removal? (Tom454)
Tom
That is good info to know, was thinking of getting a press for jobs like this but never knew the pistons needed special support. Thanks :thumbs:
That is good info to know, was thinking of getting a press for jobs like this but never knew the pistons needed special support. Thanks :thumbs:
08-21-2003, 12:35 PM
#5
Instructor
Re: Pressed piston pins..Removal? (Fevre)
You need the special adapters to hold the piston so that it's supported by the side next to the pin....not around the outer edge. Look at that part of the piston and you will little "pads". The adapters fit against the pad to prevent any side loads on the piston. Trying to push pins out with a press without supporting the piston in the correct spot can ruin your day....
08-21-2003, 12:37 PM
#6
Melting Slicks
Thread Starter
Re: Pressed piston pins..Removal? (Martin72)
I`ve heard that some people use an open flame to heat up the rod before the press out the pin :confused: :cheers:
08-21-2003, 01:04 PM
#7
Safety Car
Re: Pressed piston pins..Removal? (BB wowbagger)
I`ve heard that some people use an open flame to heat up the rod before the press out the pin :confused: :cheers:
08-21-2003, 03:20 PM
#8
Le Mans Master
Re: Pressed piston pins..Removal? (gerry72)
gerry72 is correct.... there is a special oven designed for heating of rods. But... if you live alone or you call the shots in your house... the kitchen oven will work well enough to get the job done if lady-luck is on your side.
The "gotcha" is that even with the correct oven, the pins don't always slide in. You still may need a press. This all depends on the amount of clearance mandated by the design of the wrist pin/rod combo you are working with. So working with a kitchen oven, you are playing the odds.
Ovens are also used for heating up aluminum heads prior to insertion of new iron valve guides. For example... the old Corvair heads. In this case, the guides are frozen while the head is cooking. Then you have a few seconds to get it all right before the temps neutralize each other.
I never use heat to remove the pins because I have a press and the correct jig(s). The jig holds the piston to avoid egg shaping the piston or skewing the centerline of the two pin bores. Skewing the piston pin centerlines makes it very difficult to re-insert the pin if you need to re-use the piston. (for example if you are just changing out a messed rod)
The pin arbors allow you to remove the piston/pin from the rod without damaging the rod. Banging them out is a no-no because the pin end mushrooms and then it messes up the rod end on the way through.
The "gotcha" is that even with the correct oven, the pins don't always slide in. You still may need a press. This all depends on the amount of clearance mandated by the design of the wrist pin/rod combo you are working with. So working with a kitchen oven, you are playing the odds.
Ovens are also used for heating up aluminum heads prior to insertion of new iron valve guides. For example... the old Corvair heads. In this case, the guides are frozen while the head is cooking. Then you have a few seconds to get it all right before the temps neutralize each other.
I never use heat to remove the pins because I have a press and the correct jig(s). The jig holds the piston to avoid egg shaping the piston or skewing the centerline of the two pin bores. Skewing the piston pin centerlines makes it very difficult to re-insert the pin if you need to re-use the piston. (for example if you are just changing out a messed rod)
The pin arbors allow you to remove the piston/pin from the rod without damaging the rod. Banging them out is a no-no because the pin end mushrooms and then it messes up the rod end on the way through.
