ROTAX HYDRAULIC LIFTERS

[Area-51]

Does anybody know who manufactures and supplies Rotax lifters for the 9XX engines?
 

Just need an answer about manufacturers and suppliers, thanks.

[Area-51]

Its ok, found it, Johnson HT-900; Laser etched on the lifter

 

351 Windsor and 4.1 straight 6, thought they looked familiar.

 

Guess Rotax knew where all the real power always comes from 😄

 

 

[Area-51]

No, i did not answer my question well enough. Rotax have changed the part number for both the lifter and lifter set a lot prior to 2008, and a few times since.

 

Today I tore down an old 912 and it did not have Johnson lifters in it, and they still looked ok after 2000hrs use, where as the Johnsons are heading to the bin at just 100hrs. (Maybe they were a bad batch).

 

Does anyone have any info on this?

Edited August 22, 2023 by Area-51

[facthunter]

What's your failure mode? Bottom contact surface? Those lifters are built with close tolerances but they are cheap because so many are made.  They are only hard cast iron.  Nev

[Kyle Communications]

I have ford lifters in my rebuilt 912ULS with big bore for the S-21

 

[facthunter]

I'm informed that Most of that stuff available here  now is from China.. That style of lifter is  heavy compared to other designs that are available in more modern motors Nev

[Area-51]

[Area-51]

Inlet exhaust, both showing similar results on four of the eight.

[Area-51]

8 hours ago, Kyle Communications said:

I have ford lifters in my rebuilt 912ULS with big bore for the S-21

 

How many hours since fitted or removed and inspected?

[Area-51]

Have been trawling through various forums.

Apparently Hylift Johnson, Michigan are produced in Michigan from imported Taiwanese manufactured blanks. 

 

Johnson Lifters, Michigan (in the rotax) are wholly manufactured on site in Michigan.

 

 

 

[facthunter]

They should run a bit off centre so they rotate. In most motors they will have higher valve spring pressures than in the Rotax.  My advice is from an  engine builder who tried many  suppliers here. There's no suggestion from any of them that the lifters are unsatisfactory. IF some wore prematurely there has to be a reason. Were the camshaft lobes pitted? Nev

[Kyle Communications]

The engine hasnt been run yet. My cousin is a racecar engine builder and he rebuilt the engine for me. It is also fully balanced and has a big bore kit fitted. He is also a Rotax certified engine repairer as he is a pilot and instructor as well.

He told me he used the ford lifters as they were the best. The main thing is the cam grind. He did the cam as well. The lifters must rotate as the engine turns over otherwise the cam lobe of lifters will wear. This is my engine 

 

 

[Kyle Communications]

The cam lobe shape at the top has to do with how and why the lifters rotate. Edge had a issue with their hot cams that were not doing this until someone worked out that this was the issue

 

[facthunter]

It's usually done by offsetting the cam and having a slight doming of the lifter face.   It would be extremely difficult to have a part of the cam out of true  When you grind cams you are usually traverse when grinding (not plunge). You would end up with a slight slope on the whole profile . NEVER seen that done for the purpose of rotating the follower. Nev

[Area-51]

1 hour ago, facthunter said:

It's usually done by offsetting the cam and having a slight doming of the lifter face.   It would be extremely difficult to have a part of the cam out of true  When you grind cams you are usually traverse when grinding (not plunge). You would end up with a slight slope on the whole profile . NEVER seen that done for the purpose of rotating the follower. Nev

This is all correct, however the 9XX cam lobes do not appear to be offset to the lifter, but they may very well be machined with a slight taper on the rear of the lobe; have not had one out and dial gauged yet to verify.

 

Have read in a lot of auto performance forums engineering shops, after trialing all the brands just use Johnson Michigan produced lifters.

 

The latest hydraulic lifters used in the 915is look to be totally flat bottomed rather than convex.
 

Latest lifter technology by COMP uses application of a diamond shield friction coating on the lobe contact face. And it seems to be holding up in the field.

[Area-51]

2 hours ago, Kyle Communications said:

The engine hasnt been run yet. My cousin is a racecar engine builder and he rebuilt the engine for me. It is also fully balanced and has a big bore kit fitted. He is also a Rotax certified engine repairer as he is a pilot and instructor as well.

He told me he used the ford lifters as they were the best. The main thing is the cam grind. He did the cam as well. The lifters must rotate as the engine turns over otherwise the cam lobe of lifters will wear. This is my engine 

 

 

They are definitely rotating!

 

Are the lifters standard rate leak down or fast rate? Any EDM port to the lobe face? What brand lifter are they?

[Area-51]

2 hours ago, Kyle Communications said:

The cam lobe shape at the top has to do with how and why the lifters rotate. Edge had a issue with their hot cams that were not doing this until someone worked out that this was the issue

 

I don't expect to find the camshaft at fault here, but i could be wrong. 50% faulty lobe grind in a production facility the size of Rotax just doesn't make sense, but I could be wrong again. 
 

Will try another set of fresh lifters first and see if they spin as in your video.

[facthunter]

The cam surface is  the most critical item  in a motor to lubricate requiring anti scuffing additives which are not compatible with  catalytic converters so are missing in many oils for road use. Roller followers are the best way to get around this. . . Agree about the latest offerings being flat. I never liked the slight convex idea.. Offset is the best way to go. You have to ensure the contact are a doesn't go beyond the edge of the follower, (like it did with one Jabiru set up (a fundamental oversight).  Nev

[onetrack]

That looks suspiciously like a lube oil problem to me. Does the oil you're using have specific cam and lifter additive such as ZDDP?

Zinc is being reduced or removed from current oils as the zinc and phosphate additives coat the precious metals in catalytic converters and damages their proper functioning.

[Area-51]

19 minutes ago, facthunter said:

The cam surface is  the most critical item  in a motor to lubricate requiring anti scuffing additives which are not compatible with  catalytic converters so are missing in many oils for road use. Roller followers are the best way to get around this. . . Agree about the latest offerings being flat. I never liked the slight convex idea.. Offset is the best way to go. You have to ensure the contact are a doesn't go beyond the edge of the follower, (like it did with one Jabiru set up (a fundamental oversight).  Nev

Modding out the crankcase to retain roller lifters would be a good update providing the camshaft's valve timing still functions correctly afterward. Certain that would come with other failure moments.

 

Really not convinced by the 9XX lobe profile either, it's extremely acute with very little duration at the top, but the engines fly pretty reliably and that's what matters most to me.

[Area-51]

4 minutes ago, onetrack said:

That looks suspiciously like a lube oil problem to me. Does the oil you're using have specific cam and lifter additive such as ZDDP?

Zinc is being reduced or removed from current oils as the zinc and phosphate additives coat the precious metals in catalytic converters and damages their proper functioning.

The previous owner being overly cautious and everything by the book by nature, motor would of been using what ever Rotax recommended, prob SHELL AERO SPORT+
 

4 out of the 8 lifters were not rotating as required; end of story. The other 4 lifters are as good as new.

Edited August 24, 2023 by Area-51

[Kyle Communications]

49 minutes ago, Area-51 said:

They are definitely rotating!

 

Are the lifters standard rate leak down or fast rate? Any EDM port to the lobe face? What brand lifter are they?

I am not sure. I trust Jim's experience and vast knowledge on what to put in engines and how to rebuild them. He does all the machining himself and also the cam grinding. The cam lobes must have a slight curve at 90 deg to the cam lobe. This is what makes the lifters rotate that little curve and it cant be too much or too little either it has to be just riht he tells me. All I know is they are lifters for Ford engines. He also has a engine balancer and a heap of gear there. He is always flat out doing engines for the racing guys that when you give him a job to do for a relative you have to be patient as he does it as he gets the time. Some pics of the rebuild from when I got the engine. It was a 2000 hr 2015 engine that had been well maintained out of a Tecnam at a local flying school. You can see the cam being reground

 

 

 

[Area-51]

2 hours ago, Kyle Communications said:

I am not sure. I trust Jim's experience and vast knowledge on what to put in engines and how to rebuild them. He does all the machining himself and also the cam grinding. The cam lobes must have a slight curve at 90 deg to the cam lobe. This is what makes the lifters rotate that little curve and it cant be too much or too little either it has to be just riht he tells me. All I know is they are lifters for Ford engines. He also has a engine balancer and a heap of gear there. He is always flat out doing engines for the racing guys that when you give him a job to do for a relative you have to be patient as he does it as he gets the time. Some pics of the rebuild from when I got the engine. It was a 2000 hr 2015 engine that had been well maintained out of a Tecnam at a local flying school. You can see the cam being reground

 

 

 

Lucky you! Should run really nice. They are a really simply and sweet engine.

[Kyle Communications]

The lifters are HT900 and ones NOT made in China.

 

I have never heard of lapping in lifters as the surface of the lifters is extremely hard. 

 

 

[facthunter]

You CAN lap hard metals. If it's soft the grit gets in the soft metal. You usually grind hard metals even gears if you require the extra accuracy. It's a relatively expensive operation. The valving parts of the lifter may be lapped to some former like you used to lap valves in your car. Honing is used often also. That bottlebrush Hone you often see should be turfed into the garbage. I wouldn't put one near an engine.  Nev