Installing Kelsey Hayes Caliper Pistons ?

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694spd

694spd

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I'm finally started to reassemble my 4 piston Kelsey Hayes calipers. I'm going to using DOT 5 in the system so I'm also using the same to lube the piston seals and outside walls of the pistons. I installed the new seals in the bores, but I'm having a lot of trouble installing the new pistons. They seem to be too tight. It took everything I had to push the pistons in. Now I can't even pull them out with my fingers. This just does not seem right as I'm figuring that the darn things are going to end up hanging up on me when installed. Any opinions on this??
 
I do a lot with those four piston Kelsey Hayes disc brake calipers, so i will give you my 2 cents worth on the subject.
I read that you wrote "new" pistons.
How many? All 8 of them, or just a couple that needed replacing?
Were these calipers sitting around unused, for years, or were they in service needing a rebuild, when doing a brake job?
Did you scrape out all the crud, rust, that may have accumulated in the seal groove, in the bore, before you put in the new seal?
How about honing, sanding, the bore itself, before installing the new pistons?
When i rebuild these calipers, they have been sitting unused, for years and years, before i get them as cores to rebuild.
I use a Dremel, and a "flap wheel" to clean up the bores in the caliper.
You do any clean up of the bores, to remove any old crap that accumulates?
New pistons can sometimes be "tight" going in, but if they are lubed up properly, with slippery, assembly lube, i never have seemed to have any trouble.
I use a product since the 1980's called McKay Assembly Lube, but it is very hard to find, and purchase in this day and age.
Just hope that you don't pinch the seal in the bore when installing the new pistons.
Well, my two cents.
Good luck with the rest of them.
Jim V.
hemi71x



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I just took these pictures. The car had sat for 40 years. I had a hard time getting the old pistons out. Most of the problem was rust on the pistons. The bores were in good shape. Just cleaned them up with Scotch Brite. The calipers were glass beaded. I have 8 new pistons.
I read one of you earlier posts about the McKay Lube, but I have been unable to find any so far. I have also heard where some people have used silicon grease before. Not sure if that is the right way to go though. I also wondering now if maybe I should lube the seals with DOT 3 instead of DOT 5, if that would make any difference?

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Your calipers look really clean, so you blew my theories out of the water.
I see you put the piston in, and after that the dust seal.
I never did it that way.
I put the piston seal in, then the top dust seal, and then the piston.
Guess your method can work too, but whatever works for you, and gets the task done.
A vendor on ebay used to sell a boat load of that McKay Assembly Lube, but he wrote the factory had a big fire, stopping production of the McKay products.
 
It requires a little emphasis when you push the pistons in. It could be possible the seals got cockeyed during the process and wedged your piston. I lubed mine with Dot5 and they went in ok but it would probably worth in your case to use something more slippery such as what hemi71 recommended. You will probably need to use air, etc to get them out again. I also installed dust seals first before the pistons. My restore thread has some fairly detailed pics of my caliper rebuilding process.
 
Just a follow up here. I received the Centric assembly lube last week. Boy did it make a big difference. The pistons went in without the battle that I was having before.

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mopower440 said:
How difficult is it to rebuild these calipers?
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Took a little time, but not too difficult IMHO. The most difficult part for me was trying to get the old pistons out, but was able to do it with some air pressure. If you look at my restoration page below I have some documentation on my caliper rebuild starting at post #13. Rock Auto sells rebuilt calipers for about $50 if you have a good core to exchange. If not, then it will be about $100 per caliper.
 
Cuda68Scott said:
Took a little time, but not too difficult IMHO. The most difficult part for me was trying to get the old pistons out, but was able to do it with some air pressure. If you look at my restoration page below I have some documentation on my caliper rebuild starting at post #13. Rock Auto sells rebuilt calipers for about $50 if you have a good core to exchange. If not, then it will be about $100 per caliper.
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Let me ask you this..could i re-use my pistons and just run some smooth sand paper over them? I bought this whole brake setup freshly rebuilt about 16 years ago..new rotors, pads and rebuilt calipers. They spent the first few years in my house till i got my garage built and then they stayed in there until a few weeks ago when i FINALLY got around to doing this job. SO, i dont think they are in too bad of shape inside but i do think they are stuck because i took the car for a first drive yesterday after installing them and i have to literally stand on the pedal and it just barely slows down. Cant even lock them up in my gravel driveway!
 
Those calipers came out really nice. Good job!
 
Hard to say what kind of corrosion they had sitting around for 16 years - maybe just some gunk holding them in the cylinder, but also our friend named Rusty may have paid a visit. If they look OK after you get them out and inspect them, then yes. I think you will have to look carefully in the seal grooves - any big pits in there would be a point where I would consider new ones.
 
Cuda68Scott said:
Hard to say what kind of corrosion they had sitting around for 16 years - maybe just some gunk holding them in the cylinder, but also our friend named Rusty may have paid a visit. If they look OK after you get them out and inspect them, then yes. I think you will have to look carefully in the seal grooves - any big pits in there would be a point where I would consider new ones.
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ok thanks! Trying to decide on rebuilding these or get new ones..rebuilding will be close to 100 bucks, replacing will be 200..i have already spent over my budget on this, the only reason im hesitant on rebuilding them is failing at the rebuild, but at the same time, doesnt seem too bad of a job..whats the chances of screwing up the o-ring seals when installing the new pistons?
 
The seals should go in pretty easy if you use some assembly lube - a few posts up are some discussions on the lube.
 
Cuda68Scott said:
The seals should go in pretty easy if you use some assembly lube - a few posts up are some discussions on the lube.
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so basically i can pop the pistons out with air pressure, clean up the bores with 320 grit paper, wash them out, then install the new pistons and seals and be done?
 
mopower440 said:
so basically i can pop the pistons out with air pressure, clean up the bores with 320 grit paper, wash them out, then install the new pistons and seals and be done?
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Yep. If everything looks ok after you pop them out, you may only need to clean things up with a degreaser and put new seals in.
 
Cuda68Scott said:
Yep. If everything looks ok after you pop them out, you may only need to clean things up with a degreaser and put new seals in.
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is there any chance that i may not be able to get the pistons out? on one of the calipers, 2 pistons on one side werent moving with the air, but i didnt try REAL hard either..I just dont want to spend the money only to find out i cant do it..
 
mopower440 said:
is there any chance that i may not be able to get the pistons out? on one of the calipers, 2 pistons on one side werent moving with the air, but i didnt try REAL hard either..I just dont want to spend the money only to find out i cant do it..
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I recall one or two of mine were stubborn but the air pushed them out far enough that allowed me to grab them with pliers and muscle them the rest of the way. Some guys are successful using a grease gun an basically hydraulic them out. That is likely safer than using air pressure as those pistons can become projectiles with air behind them! I can’t remember how they connected it for grease,probably a zerk fitting into caliper.
 
RustyRatRod said:
Those calipers came out really nice. Good job!
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Thanks, here is the before picture of one of my calipers that I rebuilt.
My recommendation to buy new pistons from Rock Auto. They are not too expensive.
Also make sure you buy the assembly lube. Don't try assemble them using brake fluid.

As for pushing out the pistons with air. One will always pop out before the other and now you have loss you back pressure to push out the other.
With the two halves to the caliper apart, install a brake pad on the face of the two pistons and hold it there with a C-clamp. Apply air pressure to the the caliper, then slowly loosen the C-clamp allowing both pistons to move out of there bores at the same time.

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Kelsey Hayes 4 piston calipers help

Read this posting of mine from probably going on 7 years ago.
Lucky i save these things in the computer files.
Wish they make some replies a "sticky" as people ask these type of questions every other month it seems, and i don't have the attention span any more in my old age to keep replying.
Click on the pictures link, as they will still work, even after all the board upgrades during the past.
 
694spd said:
Thanks, here is the before picture of one of my calipers that I rebuilt.
My recommendation to buy new pistons from Rock Auto. They are not too expensive.
Also make sure you buy the assembly lube. Don't try assemble them using brake fluid.

As for pushing out the pistons with air. One will always pop out before the other and now you have loss you back pressure to push out the other.
With the two halves to the caliper apart, install a brake pad on the face of the two pistons and hold it there with a C-clamp. Apply air pressure to the the caliper, then slowly loosen the C-clamp allowing both pistons to move out of there bores at the same time.

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what can I use for assembly lube that is readily available besides that exact stuff you had? white lithium grease?
 
Here in the rust belt..... some of those pistons can be really hard to remove. What I have done is drill a hole thru the piston(s) you are having trouble with, then tap threads into the piston. Screw a "long" grade 8 bolt with the end rounded off nicely, into the new threads, all the way in, keep tightening, this will push the pistons out. Use penetrating oil around the piston also. Drill piston in center. It works for me
Dave
 
barracudadave67 said:
Here in the rust belt..... some of those pistons can be really hard to remove. What I have done is drill a hole thru the piston(s) you are having trouble with, then tap threads into the piston. Screw a "long" grade 8 bolt with the end rounded off nicely, into the new threads, all the way in, keep tightening, this will push the pistons out. Use penetrating oil around the piston also. Drill piston in center. It works for me
Dave
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That is a great idea Dave!
 
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