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| Shroppy Member Since: 25 Feb 2016 Location: Shropshire Posts: 866   
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This is a bit of a long read so please bare with me....
As part of my 127 rebuild I'm rebuilding the transfer box and gearbox myself, partly because I think it's within my capabilites and partly because I can't really afford to pay someone else. A good friend of mine offered to aquablast my casings, he avoided any machined faces/internals and only blasted the external faces. I was happy with this as the risk of anything embedding itself was very slim and I could wash the parts thoroughly. I opted for a sleeved LT230 casing to complement the above and prevent any future issues with the intermediate shaft. The casing was supplied by a well known gearbox specialist (not Ashcroft) who I will not name. Unfortunately the first casing supplied had a worn front input bearing housing and was replaced swiftly to the suppliers credit. Yesterday the replacement arrived and looked good. 
That is until I inspected it more closely and found steel shot media in the threads, I set about washing and washing and washing the casing but each time more media came out. This is about 1/10th of the media I washed out:  Click image to enlarge So this morning I called a local specialist engineering firm to see if they would ultrasonically clean the casing to remove any remaining media for me. I'm paraphrasing now but the response was something like 'Yes we can do that, but we never recommend blasting any engine or gearbox components as the media embeds itself and is released when the casing heats up. So, if the transferbox fails we can't accept any responsibility. I would get back onto the supplier and request they clean it and warrant it against causing failure or supply you a new non-blasted casing.' B*ll**ks I thought to myself, have I inadvertently ruined all my casings? Well I'm hoping not, the guys at bad obsession motorsport had their project Binky's gearbox casings aquablasted and didn't seem too concerned. I also trust my friends engineering judgement (he is a mechanical engineer) and I washed the casings incredibly thoroughly, I'll probably get them ultrasonically cleaned just to be sure though. As for the sleeved casing, what do you think? Steel blast media is likely more harmful than abrasive/glass media if it isn't all removed but I'm led to believe the gearbox specialist applies the same process to all their casings... I guess the magnetic drain plug will help but not if it finds its way into a bearing first. So I suppose my options are; 1 - Replace all casings with no blasted casings to be safe. 2 - Use the aquablasted casings but have them ultrasonically cleaned to be safe. Return the LT230 casing and request a replacement or have my original sleeved and cleaned. 3 - Use all the casings but have them ultrasonically cleaned to be safe. I'd appreciate any feedback / personal experience related to the above please. I don't want to cause unnecessary issues with the supplier but as I'm fitting an Ashcroft ATB and new bearings/gears I don't want to risk them failing either!! 1985 127 V8 Build Thread Series 2 109" Series 1 80" |
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10th Apr 2021 7:50am |
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| Shroppy Member Since: 25 Feb 2016 Location: Shropshire Posts: 866
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Thanks Clemmo, I do have a spare LT230 I can use for the casings and can hopefully source a replacement R380 tail housing if necessary.
It's a classic case of 'wish I'd asked first'.... also now wondering whether I would have been better off going down the mech/auto engineering route instead of structural.  Still, something to learn from. 1985 127 V8 Build Thread
Series 2 109" Series 1 80" |
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10th Apr 2021 8:07am |
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| jimbo55 Member Since: 15 Jul 2020 Location: Midlands Posts: 399
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As Clemmo says I wouldn’t risk it
I priced up doing a full rebuild on my transfer box (to include an atb) and was quite surprised at how much the parts alone added up to compared to just buying a built box, decided for the time it would take me it wasn’t worthy doing it myself and would just pay someone to do it. Although I still haven’t got round to doing anything with it |
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10th Apr 2021 8:55am |
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| Shroppy Member Since: 25 Feb 2016 Location: Shropshire Posts: 866
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At this point I would agree that buying a recon LT230 and R380 would have been a lot easier and probably cheaper!! But at least this way I get control of what goes into the box. 1985 127 V8 Build Thread
Series 2 109" Series 1 80" |
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10th Apr 2021 9:04am |
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| Shroppy Member Since: 25 Feb 2016 Location: Shropshire Posts: 866
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So a little more digging.....
It transpires that everyone I have spoken to blast cleans their transmission casings prior to rebuild/sleeving with either glass or steel media. The supplier I purchased my casing from is happy to refund me but has informed me that the same process is applied to all their casings and they've never had an issue. So where does this leave me? Well having pondered it for the last 48 hours I'm still not happy to fit a casing that might have embedded blast media because I don't want to ruin any of my nice new gears. It does raise the question though, if it's common practice and there are many thousands of rebuilt transfer and gearboxes running round then how bad can it be? 1985 127 V8 Build Thread Series 2 109" Series 1 80" |
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12th Apr 2021 7:46am |
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| ashtrans Site Sponsor Member Since: 08 Nov 2008 Location: Harpenden Posts: 257
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Hi,
we blast with glass media which turns to dust should any be left in there (which we obviously try to avoid), I once tried aluminium oxide, very bad expensive mistake, the media lasts very well (unlike glass) but if any gets left in the box it eats the internals. Dave |
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12th Apr 2021 10:02am |
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| X4SKP Member Since: 29 Nov 2013 Location: Berkshire Posts: 2295 
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Hello Shroppy
I'm an Engineer (New Product Development) and also, up to a point, a keen car mechanic. I also know a few highly respected garages / workshops... where I spend too much time 
so over the years have picked up 'how they do things' (this helps me to judge where my line is). This is my take... Glass Media on Al' castings should be OK... there is however real skill in using this correctly, pressure, closeness to surfaces etc, also there needs to be a near forensic level of post process cleaning to ensure that all is well, bottom line is that if any is left / embedded it will probably be non damaging when (not if) it lets go, you should assume that heat cycles and vibration will ultimately dislodge any 'not supposed to be there' particals. The use of Steel Media provides another level of anxiety for Al' casings and from my experience, most would avoid, it can be the beginning of a host of problems and your LT230 should go back IMO (from your description) if there is even a suspicion that there may be 'shot' inside. Hope you find a way through that works... SKIP
https://www.defender2.net/forum/topic83242.html |
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12th Apr 2021 10:31am |
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| windy81 Member Since: 14 Mar 2018 Location: North Wales Posts: 311  
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If the blasting media is walnut casings, i cannot see it doing damage. If they are steel i'd be very concerned.
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12th Apr 2021 11:05am |
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| Shroppy Member Since: 25 Feb 2016 Location: Shropshire Posts: 866
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Thanks all for your responses, the casing in question which has been blasted with steel media is going back to the supplier. For the reasons discussed in this thread I'm not going to risk it!
As for the casings that have been aquablasted, I am fairly sure it uses broken glass media. I will double check this and if correct I think I'll have the casings ultrasonically cleaned to remove any remaining traces of media and find someone who will sleeve but not blast the main casing. This seems a balanced approach as I am confident the internals/machined faces were not blasted (they still showed oxidation/dirt/sealant) and as a result any media inside the casings should not be embedded. Failing that I'll use another set of casings that haven't been blasted and start a fresh. How does that sound? 1985 127 V8 Build Thread Series 2 109" Series 1 80" |
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12th Apr 2021 11:59am |
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| windy81 Member Since: 14 Mar 2018 Location: North Wales Posts: 311
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proper job!
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12th Apr 2021 12:27pm |
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