Flex hone for deglazing/honing cylinders

Flying Torquewrench · 03-05-2021, 11:46

As per my project thread I am replacing the piston rings on my RD28T. To help bed in the rings the bore should be honed or deglazed.

I have already decided that I will not be honing it in the traditional sense. The traditional way is the three pronged honing tool and send it up and down the cylinder bore. There are several reasons for not using this method:

1) The bores are currently not 100% straight and therefore this tool with not get to the low spots.
2) It takes off more metal and therefore increasing the bore diameter, which in turn results in the new rings being closer to the outer limit.
3) The tool needs to be held perfectly otherwise the top (or bottom) of the stones grinds off more metal.

I am looking at using a Flex hone. This will follow the contours of the cylinder and makes sure that every bit of the cylinder gets deglazed. Cast iron rings will be used on the pistons as these are a little bit more flexible to seal an out of round cylinder compared to a more modern equivalent.

Has anybody used a flex hone?

makeitfit · 03-05-2021, 16:28

I looked onto it when I rebuilt the Black Pearl engine. Like you my block was out of symmetry but still within tolerance. As such I paid a man like 50 quid or something to do it properly. Yes it opens the bore but then it is round and true.
I'm not convinced the wrought iron rings will actually do as you say.

solarman216 · 03-05-2021, 17:14

I have never come across anything other than cast iron rings

Rick

Flying Torquewrench · 03-05-2021, 18:40

Rick, there is a multitude of different materials for rings to be made off. Being either the whole ring or the coating of the ring.

A cast iron ring will bed-in a lot better compared to, for example a chrome ring. A chrome ring takes a lot longer to bed-in and takes a rougher cylinder due to its hardness. With a cast iron ring you can even get away with not honing at all. It will bed-in fine on a smooth surface.

SAE did research into this and they came to the conclusion that a non honed bore with cast iron rings had better compression after 10000 miles compared to a honed bore with chrome rings.

solarman216 · 03-05-2021, 18:45

Learning every day, Rick

03-05-2021, 11:46	#1
Flying Torquewrench Senior Member Join Date: May 2011 Location: Worcestershire Vehicle: Nissan Patrol Y61 2.8TD Posts: 1,152	Flex hone for deglazing/honing cylinders As per my project thread I am replacing the piston rings on my RD28T. To help bed in the rings the bore should be honed or deglazed. I have already decided that I will not be honing it in the traditional sense. The traditional way is the three pronged honing tool and send it up and down the cylinder bore. There are several reasons for not using this method: 1) The bores are currently not 100% straight and therefore this tool with not get to the low spots. 2) It takes off more metal and therefore increasing the bore diameter, which in turn results in the new rings being closer to the outer limit. 3) The tool needs to be held perfectly otherwise the top (or bottom) of the stones grinds off more metal. I am looking at using a Flex hone. This will follow the contours of the cylinder and makes sure that every bit of the cylinder gets deglazed. Cast iron rings will be used on the pistons as these are a little bit more flexible to seal an out of round cylinder compared to a more modern equivalent. Has anybody used a flex hone?

03-05-2021, 17:14	#3
solarman216 Off road maniac Join Date: Dec 2009 Location: Bexhill on Sea Vehicle: Y60 Patrol Me, 3 ltr Mrs Posts: 17,431	I have never come across anything other than cast iron rings Rick __________________ Ex banger racer now off road maniac Lokka on the front with manual hubs Diff lock on rear 3 inch SS straight through exhaust Manly winch bumper with 13000 lb winch 10 spike ground anchor, with multiple straps and blocks Super strong body cills capped with scaffold pole 20% stronger springs all round aggressive off road tyres on wheels so just swap. Aim to get stuck and be completely self sufficient in extraction, love getting muddy, 2ft deep is good but rare.

03-05-2021, 18:45	#5
solarman216 Off road maniac Join Date: Dec 2009 Location: Bexhill on Sea Vehicle: Y60 Patrol Me, 3 ltr Mrs Posts: 17,431	Learning every day, Rick __________________ Ex banger racer now off road maniac Lokka on the front with manual hubs Diff lock on rear 3 inch SS straight through exhaust Manly winch bumper with 13000 lb winch 10 spike ground anchor, with multiple straps and blocks Super strong body cills capped with scaffold pole 20% stronger springs all round aggressive off road tyres on wheels so just swap. Aim to get stuck and be completely self sufficient in extraction, love getting muddy, 2ft deep is good but rare.

03-05-2021, 16:28	#2
makeitfit Senior Member Join Date: Apr 2008 Location: on the beach WEST WALES Vehicle: Maverick TDi BLACK mmm Posts: 15,136	I looked onto it when I rebuilt the Black Pearl engine. Like you my block was out of symmetry but still within tolerance. As such I paid a man like 50 quid or something to do it properly. Yes it opens the bore but then it is round and true. I'm not convinced the wrought iron rings will actually do as you say.

03-05-2021, 18:40	#4
Flying Torquewrench Senior Member Join Date: May 2011 Location: Worcestershire Vehicle: Nissan Patrol Y61 2.8TD Posts: 1,152	Rick, there is a multitude of different materials for rings to be made off. Being either the whole ring or the coating of the ring. A cast iron ring will bed-in a lot better compared to, for example a chrome ring. A chrome ring takes a lot longer to bed-in and takes a rougher cylinder due to its hardness. With a cast iron ring you can even get away with not honing at all. It will bed-in fine on a smooth surface. SAE did research into this and they came to the conclusion that a non honed bore with cast iron rings had better compression after 10000 miles compared to a honed bore with chrome rings.