Does plating a cylinder change the castings properties?

MikeS

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#1
Curious as my black cloud follows me.

First I am not complaining here as I have no issues with the plater or Eric's services..

I have a big bore RM85 that Eric has done. History goes like this:

1. Sept 2002 O3 Cylinder made/plated at factory.
2. Oct   2002 Eric bores and replates it.
   May  2003 Bike Overheats BAD. Eric hones cylinder (says it is warped but it may last for a race or 2)  (N/C... THANKS ERIC)
3. June 2003 Eric sends it out for replate. The process is flawed and cylinder needs to be bored some more to clean up warping. It is replated Again.
4. Thicker coating is applied. (N/C for rebore and replate as the warpage got overlooked. Only got charged for a normal replate)
Sept 2003 Plating falls off after approx 6 hours of race time.
5. Oct   2003 Replated again (2 days ago) ( N/C Thanks Eric and US Chrome)

Well Yesterday I recieved the cylinder as promised (THANKS AGAIN ERIC). Last night I assembled everything. I torque the head bolts in 3 stages with a Good Torque wrench. The 2 rear head bolts pulled the threads out of the cylinder. Well I put 2 heli coils in. I assembled it again and the front 2 pulled out. OK ... I installed 2 more heli coils. I have not assembled it again as it got late and I was POed. I plan on getting some new bolts/studs this morning just incase. Junior has a race Saturday (tomorrow) morning.

My Question here is can all that plating (5 times) cause the threads to become brittle ?

Mike

 


 
 
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#3
Mike - I'm not sure if the plating strip bath has long term effects or not. I'll be talking to Eric later and see what his thoughts are.
 

jmics19067

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#4
I am more inclined to think the threads gave out in the aluminum from the constant working in and out of the studs. Interesting stuff though.
 

MikeS

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#5
Rich
I tried to call Eric but his number kept going to the Phantom voice mail box.

Endo
Sleeving is not possible in this senario.

JM

I had the studs in and out about 8 times I figure. So I assume that is possible also.

Well .... The head is smoke at this point because 2 of the 4 helicoils let go. I salvaged one by using an extra long coil. Problem is the aluminum is crumbleing. Even tapping it with oil made for the aluminum will not allow a clean cut for the helicoils. It was too late last night and I overlooked that.

I put some loctite crap that has hardened on the one and it took the torque. Even after a hot cold cycle of breaking the topend in it has held. It needs to hold for an hour or so for tomorrows race. I have 3 weeks before the next race so I will try one more patch on the bad coil.
I am patching only to make 2 more hours of racing. I ordered a new cylinder but I want Eric to try a stroker and long rod kit and I do not want to cut the new cylinder base way down to match the current configuration.

Something new to add to the racing diary...
 

jmics19067

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#6
I salvaged one by using an extra long coil. Problem is the aluminum is crumbleing. Even tapping it with oil made for the aluminum will not allow a clean cut for the helicoils.

hmmm well the aluminum threads pulling out from repeated use wouldn't explain that.
 
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#7
I have had the same thing happen to me after I welded the transfers on some cylinders. I let them get too Hot. Some of the studs wouldn't come out without stripping. I drilled oversize and used a thread forming tap ( no flutes ) with a good moly lubricant I believe it was made by Castrol for tapping. I used a die and made some plugs out of 6061 AL installed with JB weld and tapped them for new studs. You did say the engine overheated. How hot is the plating bath? Any ideas alloy and composition is used in cylinders?
 

MikeS

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#8
I think JB weld will be my next choice.

We made 45 minutes out of the 65 for the race. The bike ran to the finish and we lost only one place. The stud was lose and the coolant was gone.

This cylinder was warped around .015 out of round. It was run real hot a few times as it had the previous season as an 85. I have 6 piston from the collection that are siezed from our overheating problem. Overheating was solved a few months ago after the 2nd last replate.
 
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#9
I am not for sure, but every time youre cylinder needs to be replated,the old nicasil has to be removed with salpetresour.And a while ago,I talked with pierre karsmakers from the netherlands(He has a very famous replating shop now)and he said that every time a cylinder is in a salpetresour bath to remove the old nicasil,the cylinder becomes more porous.Maybe thats the reason that the threads became weaker.
 
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#10
Mike, it sounds like the aluminum got too hot at some point in it's life. The situation you describe is typical of overheated aluminum. This sort of thing happens around the exhaust ports on aluminum automobile heads that have been run without water.

I hope you figure the problem out.

Chris
 

MikeS

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#11
I finally got to speak to Eric on this after 2 weeks of phone tag.

Yes it got real hot more than once.

Eric mentioned that the Suzuki cylinders have a hi silicon content. That makes them "gummy" even thread inserts are a pain to get to hold. I have given it one more shot at mending. I had some specialty studs made that are longer and they seem to go deeper into the extra long thread coils I got. I also used JB weld to secure everything in place.

If they hold great we need one more 2 hour race than I could care less.

thanks for all the comments and reading about my mess.
 

jmics19067

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#12
I can understand the high silcon content giving you troubles, Although I am by no means an expert maybe a different style of tap and tapping process is in order.Instead of a standard 4 fluted straight shank tap in the tighten half back off 1/4 style of tapping maybe something like a three spiral fluted tap in a constant feed would be better suited to that material. or some type of strange combination of type of tap ,process and or cutting fluid is needed for a clean cut.

unfortunately that will basicly leave out helicoils since I only know of type of helicoil tap <4 straight flutes>. Possibley you might be able salvage things for the long run if you could get a standard oversized tap in the right configuration for the casting and make the holes big with a clean cut thread. Then get some 6061 rod or something more tapping friendly,wind the screw in on the side of your die to cut a slightly oversized outside thread on the rod to have a slight intereference fit in the holes of the jug and loctite them in. Center drill the rod for your stainless helicoils and then loctite them in,let set clean up any loctite that could grab onto your studs and install studs.
I could see most of this work being done on a common drill press but you will most likely have to have the top of the cylinder surfaced so there in no ridges from the installed homemade nutsert rods.Whether or not water jacket holes or head gasket sealing of the fine cracks from the rod to cylinder thread is going to be a problem but if you are going to be ending up throwing the jug away I would try it as a last resort.

IF my idea pans out the way I envision it you could possibley have a very course thread holding your "nutserts" so crumbling isn't as much of a problem for thread contact at the jug and then a material more able to handle the work of removing and reinstalling the studs often.

did that come out clear? Hopefully a machinist could tell you if it is a sound idea to try.
 

bigred455

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#13
Try millenium technoligies next time!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
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Neil Wig

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#14
The old air cooled VWs had similar problems with their magnesium cases. They would pull head studs very easily. The solution is to use "case savers". Basically, these are steel threaded inserts (not helicoils). You machine the cylinder to accept the threaded insert, screw the insert in with a high strength loctite, and machine the insert flush to the cylinder. From there, you have an extremely strong mounting point for your head stud.

A little time consuming, but should provide a good permanent fix.

Later

Neil.
 

MikeS

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#15
Originally posted by bigred455
Try millenium technoligies next time!!!!!!!!!!!!!!!!!!!!!!!!!!!
&nbsp;

It would not have made a difference who did the work.

&nbsp;

I think inserts are better than coils. I have some over size inserts coming that will cut threads as they are inserted. If they donot look correct then I will get some stock and make my own.