What a Roosa Master flex ring looks like!!

Many of us on here talk about the flex ring falling apart on a RoosaMaster/Stanadyne injection pump that will cause it to plug up the injection pump. Well here are some pictures of the flex ring, governor weight cage, and the new solid weight cage that eliminates the flex ring.

Here is a new flex ring. It is just a piece of plastic/rubber with a row of hole around it. The hole fit over a row of pins that are kind of like rivets on the back of the governor weight cage and its internal drive. Its purpose was to dampen sudden changes in RPM that could cause an issue with the governor weights and cage.



Here is the old style of weight cage. You can see the pins/rivets on the back side of it. The flex ring fits over these pins/rivets. IF you look close you can see the remains of an old flex ring under some of the pins. The old flex rings where a black rubber like substance.



Here is a flex ring being installed on the old style governor cage. It is a real pain to do. It helps if the flex ring is soaked in hot water before installation.



Here is the newer style of solid governor weight cage. You can see where it does not use the flex ring. The only issue I have every had is some smaller engines may "hunt" RPMs at low idle. I have only had it happen on one tractor out of I bet fifty I have installed. This style should not be used on automotive DB pumps. They have too many sudden RPM changes. There is a newer style for them too that does away with the flex ring also. They call it and "EDI" (elastomer insert drive) weight cage.

Thanks for the info and pictures that explains it
very well. I have a 1650 Oliver with that problem,
at least now I have a visual of what is going on.

Thanks again

Thank you for taking time to post.
I learned something today already.

EID style retainer was first used on automotive applications, # 27984 with rounded heel weights in 1985 before they were ever released for ag or construction use. Olds 5.7, 4.3, GM 6.2 and 6.5 and Ford/IH 6.9/7.3. Some ag pumps that have the rounded heel weights use the same retainer. New style # 29111 is for pumps with square heel weights used in most ag and construction pumps. Actually the latest Stanadyne pellethane flex ring holds up much better than the previous ring did, have seen them still last over 25 years. I think of the flex ring as a safety fuse as high hour pumps should have the pilot tube and DV spring replaced at least. Have seen heads lock up when the spring breaks and locks up through the rotor ports. Always enjoy your posts, keep it up!

Seller, are these kits expensive if not why dont diesel repair shops install these? Those rings seem not to last over 10 years regardless of usage hours.

The solid governor weight cage is only $40-50. The pump shops do not want a pump failure because of a rapid RPM change. So they put it back to factory specs. That way they are not liable for any thing that might go wrong down the road. Even the 1000 to 1 stuff.

In theory if you raced the engine and slowed it down a lot like in a car or pickup the non dampened weight cage could cause a governor failure. My thoughts are how many times do you race a tractor and pull it back to idle very often??? It is not something that happens with one time of doing it. We are talking about thousand of reputations. So It just about could never happen on a tractor.



My view it that many of the tractors that use the DB pumps only get used in very light conditions anymore. So the time is a bigger enemy of the components rather than usage. So I put the solid cage in. It will not fall apart because of time submerged in diesel fuel.

Thanks for the explanation. I'm thinking we will try one next time.

Hello all. Long time reader here and my first time posting...

Thanks for posting your information on this... I have been reading up on rebuilding these after my local shop wanted $550. to ''reseal'' my JDB 431 pump. My ring looks as non existent as the picture you posted above. I opted for the solid governor cage. Of course being a John Deere engine, it has the special cam advance screw that takes the Torx looking tool instead of a standard Allen hex wrench. I asked the parts guy for a hex screw instead and he said it was more than the tool. I ordered the tool and found it to be a standard T-45 Torx bit machined down on a lathe. Nice $31.00 wasted... Anyway the Stanadyne part number for the tool was 24992 and at reassembly this screw gets torqued to 360 in lbs.

I bought a Onan 30 DDA generator for $600 that didn't run for more than 3 minutes when you started it. I couldn't pass up this deal! It only has 629 hrs. Now that I have my kit and other parts, I plan on tackling it this weekend. Now I have 30,000 watts when the power goes out.

Picture of tool bit

Diesel: That tool is a joke!!!! It is NOT the correct tool to remove the cam ring screw. They are a BRISTOL screw. This means they are a straight spline. The CHEAP Torx wrench machined down still has tapered sides. IF your cam ring screw is real tight that JUNK tool will explode the head of the screw. May even twist it off in the cam ring.

Since you ordered this from Stanadyne it is all they offer to use officially. Before you try to remove the cam ring screw take a smaller pin punch that just fits inside the head of the cam ring screw. Give the punch/screw a sharp hit or two in the bottom of the bristol splines. This will usually help break them loose.

I have a regular Bristol Wrench set and a guide that screws around the cam ring screw. I still have them break every now and then. When they break you may scrap the cam ring.

This screw has NOTHING to do with John Deere. All of the Roosa-Master/Stanadyne DB pumps used this type of cam ring screw.