Wren 54 starter problem

[Jon H]

My turn to ask advice

Anyone with a wren 54 had issues with the starter sticking on? Once the engine is up to idle speed the thing wont retract so I have to shut it down. Any ideas how to fix it?

[cymaz]

John, I bet someone on the LMA forum would know.

Or the jma?

Edited By cymaz on 16/06/2017 06:36:57

Edited By cymaz on 16/06/2017 06:46:34

[Denis Watkins]

You may have seen this already on the internet Jon

But here goes

Your problem is the starter motor may be too close to the turbine.
undo the three grub screws that secure the motor in place and pull the motor out very slightly. tighten one grub screw up and quicky spin the motor to test it if it sticks again move the motor out a bit more untill you get a good result and then re tighten all three grub screws, as a guide the bendix (the bit that pops out as the motor spins and grabs onto the front of the prop nut on the turbine to spin it) should sit nicly on the nut when it spins. if it does stick it should unstick once the turbine has fully started

[Nigel R]

New product line for Laser coming soon?

[Jon H]

Thanks for that Denis i will give it a try and see what happens as currently it is reluctant to let go and gets stickier the higher the rpm becomes.

Nigel, funnily enough this engine is very likely to have a main shaft we made many moons ago. Its a kit built MW54 MkII with a few of the MkIII upgrades. I got it from the estate of a deceased club member and have been trying to revive it after 15 years of inactivity.

[Kim Taylor]

Posted by Jon Harper - Laser Engines on 16/06/2017 08:32:00:

Thanks for that Denis i will give it a try and see what happens as currently it is reluctant to let go and gets stickier the higher the rpm becomes.

A bit 'left field', but is the bendix 'wound' the right way. If not, the force of the engine spinning will pull it in, not spit it out.

Kim

[Jon H]

Posted by Kim Taylor on 16/06/2017 08:39:26:

Posted by Jon Harper - Laser Engines on 16/06/2017 08:32:00:

Thanks for that Denis i will give it a try and see what happens as currently it is reluctant to let go and gets stickier the higher the rpm becomes.

A bit 'left field', but is the bendix 'wound' the right way. If not, the force of the engine spinning will pull it in, not spit it out.

Kim

A valid question but yes its all the right way round. Up to about 10000rpm it lets go quite well, up to about 20k its really slow and above that its like a frightened 3 year old holding on to its mum!

[Jon H]

alas moving the motor did not cure the problem

Any other ideas?

[onetenor]

Have you got the polarity right?

[Jon H]

the engine starts, it just takes the motor with it. If it were backwards it would never engage let alone start the engine

[J D 8]

I do not know the wren 44 starter motor but it looks to me like any other starter motor of similar type known as a bendix starter where the spinning up of the electric motor throws out the bendix along a spiral groove to engage with the engine.

Once power is switched off to the motor a light spring returns the bendix to the standby position.Any muck in the mechanism or a weak spring will result in the problem you have.

Most modern cars are now fitted with pre engaged starters to overcome this problem.

Just an idea. Cheers.

[Jon H]

Posted by J D 8 on 16/06/2017 23:01:25:

I do not know the wren 44 starter motor but it looks to me like any other starter motor of similar type known as a bendix starter where the spinning up of the electric motor throws out the bendix along a spiral groove to engage with the engine.

Once power is switched off to the motor a light spring returns the bendix to the standby position.Any muck in the mechanism or a weak spring will result in the problem you have.

That is exactly the type but there is no spring in this setup and as this part was assembled by wren I can only assume it is not intended to have a spring fitted. It seems odd to me though not to have a spring.

Before starting this thread I did seek advice from Dave at Motors and Rotors. He suggested giving it a clean and light oil but as had already tried that without success he suggested I cast a wider net as he is more of a jetcat man. One thing I did notice is that the outer part is a very sloppy fit on the inner and any misalignment could easily cause a bind. How to fix this is another matter!

[Denis Watkins]

Exactly Jon, it is binding on the spriral,

If it were accessible, I would remove the unit, and look for the offending marks or ridge, where wet and dry paper could be use to buff up abnormalities

And being me, would operate the Bendix with grinding compound to relieve any small ridge

Moly slip is good too, if you can still get it, as moly is very slippery oil

These are just thoughts

You know the Bendix was designed to throw back immediately on changing spin speed, so it can only improve with polishing.

[Jon H]

What I might do is take it to work and press out the retaining pin. Then I can clean up the brass a bit more. I might grab a video of the slop as I am really not sure its supposed to be like that but have never seen another in action so cannot be 100% sure

[Martin Harris - Moderator]

Have Wren Power Systems stopped trading? I know they were formed out of the original liquidated company and there was some speculation last year but their website is still active and showing motor/bendix parts available.

Even if you don't want to buy a new bendix, they may have some advice? Could the bendix be designed to work dry or with something like graphite? Thinking very much outside the box, perhaps the oil is being flung outwards as the revs increase and causing binding by closing up the clearances?

[Jon H]

i have tried to call wren more than 20 times over the past 3-4 weeks. they never answer the phone and clearly aren't interested

[Martin Harris - Moderator]

Have you tried cleaning the bendix and running it dry? My recollection of old car versions is that you never lubricated them.

[Jon H]

Posted by Martin Harris on 17/06/2017 21:42:15:

Have you tried cleaning the bendix and running it dry? My recollection of old car versions is that you never lubricated them.

yup, tried that one too!

[Keith Simmons]

I don't have a jet turbine so can't help, but did look up the Internet about Wren turbines to get some idea what's behind the scenes. Does not look good. I understand your efforts to try to get this sorted

Have you got the wren 54 for long and did it give good service up to now?

I am sure there are servicing issues for existing owners and they do need to be maintained.

I do hope you can sort it out and is there a business opportunity market for Laser Engines to help out or would that be pouring water into the sand so to speak?

Good luck with your efforts

[Jon H]

I got the engine from the estate of a deceased club member and according to the data terminal the engine had only 4 minutes run time on it before I got it.

Given that it was in pretty poor shape as the data terminal had to be repaired (not a small soldering job I can tell you) as there was a broken wire causing it to cut out half the time. Programming the ECU with the settings in the instructions gave an engine that wouldn't even start, so I had to get creative just to get the thing to run.

I am aware of the historical issues surrounding wren, but their 'new' company is up and running and yet they are virtually impossible to contact.

Laser will never offer support for these engines as we only made one component for a short time. As I am the only person at Laser who works on the engines I can barely keep up with our own servicing without taking on more.

Regarding our servicing, if you guys could please stop crashing your engines it would be great as I am getting them back faster than I can fix them!

[Keith Simmons]

Many thanks Jon for the reply & how you got the Wren turbine.

LOL about asking us not to crush our models, unfortunately we don't learn if we don't make mistakes and it's how quickly we recover and do the correct way to minimise takes time and practice as you know well. 😎

Oh dear that there may be other issues regarding the Wren 54 turbine and not just the bendix starter and I do hope you will solve all the problems in the end and enjoy running the Wren

[Jon H]

Well, through the wonders of the interwebs I can present my floppy starter.

I think this is broken as its floppy, sticky, and had end float in the motor. It has also been rubbing on the casing that holds it on the front. If anyone else has experience with these things please let me know if they are all like this or if mine is busted.

Thanks

[Don Fry]

Sorry mate, but not flown, run for 4 minutes, don't work. You do the maths.

I do commiserate. The last crash buried an ancient 75. No damage. You must have 'ard customers.

[onetenor]

Thinking sideways it was sticking right from the start and the 4 minutes running in that state without it being noticed caused the resulting slop and wear..It never did full size starters any good either.This more than likely is what upset data terminal too. Sorry to say but the motor needs a rebuild and a new starter in MHO Plus reprogged data terminal.

Good luck contacting Wren though

John O/T

Edited By onetenor on 18/06/2017 20:04:45

[Jon H]

Posted by Donald Fry on 18/06/2017 19:05:37:

Sorry mate, but not flown, run for 4 minutes, don't work.

A peek inside with a borescope prior to me buying the engine revealed the combustion chamber to be clean as a whistle. As the chap in question became ill and then died not long after buying the engine I have no reason to believe that 4 minutes on the ECU is inaccurate. He had two turbine models in his possession and neither were airworthy at the time of his death and his friends within the club knew he never flew the engine or even ran it himself. It should be noted that over 10 years passed between his death and the sale of his gear.

All I am looking to learn at the moment is if the above video is typical of these types of starter as I have not dealt with one since I was at uni and I cant remember that far back.