timfly1

My Feedback: (1)

Hi all
I'm building a Wren MW54, Wren sent me the turbine shaft assembly. In fitting the parts together I find that the compressure will only slide on to with in a few mm of the shoulder. I contacted Wren but Sara has not e-mailed me back. I'm told on another forum that the compressure is a heated fit (100c) to the shaft. This dosent make sence to me because if I ever have to remove the compressure I'll never be able to heat only the compressure not the shaft.
It seems to me this should be a good slide fit.
Any ideas about this.
Thanks
Tim.

Jet Doctor

Hi Tim

If I recall the instructions do say that you can polish the shaft slightly and slowly to get the correct fit. You cannot heat it up as you need to remove the compressor wheel later again. My suggestion would be to put the shaft into a drill or better yet a lathe and polish the shaft with a very fine emery paper(800 grit) until you get a nice tight push fit. I have built 2 MW54's and did not encounter any problems with assembly or running them. I found the folks at Wren, including Sara to be very helpful. For the best service I would try and call them during their office hours. I know that there is a time difference to take into account.

Enjoy

Zane

timfly1

My Feedback: (1)

Yes I did contact Sara by e-mail she hasent got back to me yet. That sounds right, to polish the shaft for fit. I instructions dont say realy what kind of fit the compressor should be. I do have a lathe so this should rather easy.
Thanks for the advice.
Tim.

Woketman

My Feedback: (6)

The compressor is aluminum and the shaft is steel, right? If memory serves me, the CTE (Coefficient of Thermal Expansion) of an average aluminum is about 1.7 times that of an average steel. So heating it up to get it off should work just fine.

Robrow

Hi Tim, you should have no problem heating the compressor wheel and sliding it on the shaft. Don't worry about the actual temperature you heat it to just use a heat gun and a cloth or oven glove and a little thin lube such as WD40 on the shaft, rotate the wheel slightly as you slide it on.

To remover the wheel use the reverse procedure; because the allu wheel has a higher coefficient of expansion than the steel shaft it with loosen as it heats up.

This method has always worked well for me on dozens of engines provided the fit is not too tight.

Rob.

mr_matt

My Feedback: (10)

Yep that is how it works with almost all motors.

H.Dale

My Feedback: (3)

I've got a question. I am building my second MW54. My spinner nut will screw down about half way and then it gets tight like the threads are smaller or stripped. Is it suppose to be that way?

Also, if I ever want to take one of these engines apart what is the best way to do it? My diffuser fits pretty tight.

Hal
MS Gang Country

jason

My Feedback: (1)

There was some talk from the Wren lot about making the compressors a tighter fit so it would need heating to slide on the shaft. This makes the fit more accurate. If you want to take it off then heat it up again with a heat gun or hair dryer and it wil come off.

jason

Gazzer

I have just finished the MKIII MW 54 and confirm the compressor fit is "TIGHT"!!!

In fact having got it on, with a gentle rotating of the compressor while fitting, I could not get it off and ended up scarring my finger with a deep cut on the compressor blade trying to hold it fast whilst rotating the shaft.

I contacted Wren and was advised to use the heat method to remove but was also asked the wise question "why do you need to remove it"? Well I didn't so it stayed on, I know what to do when the time comes!!!

Gazzer