Galvanising Trailing arms
Discussion
Lots has been said about the risk of chassis distortion / need to drill holes etc so general conscensus is not to do it to a chassis.
But what about the trailing arms?
They are one mother of a piece of hardware, and I'm going to get mine shotblasted shortly.
Would I put them at risk by sending them off to be galvanised do you think?
And would galvanising them be a better form of rust prevention than anything else?
Chris
But what about the trailing arms?
They are one mother of a piece of hardware, and I'm going to get mine shotblasted shortly.
Would I put them at risk by sending them off to be galvanised do you think?
And would galvanising them be a better form of rust prevention than anything else?
Chris
Hot Dip or Electro Chris ?
I think the Electro would not coat the tube internals fully and hot Dip coating is usually heavy so you'll end up drilling the brake pipe clip and inside mounting holes out again, Or maybe the galvanisers I've used in the past were too "industrial" ?
I'll be interested in the results if you do it though...
K
I think the Electro would not coat the tube internals fully and hot Dip coating is usually heavy so you'll end up drilling the brake pipe clip and inside mounting holes out again, Or maybe the galvanisers I've used in the past were too "industrial" ?
I'll be interested in the results if you do it though...
K
I have read an article on this forum (by whoever it is that rebuilds the arms I think) that the bushes are a really tight fit in the housings and that they actually end up scrapping some when fitting them, my concern with galvanising would be that you would enhance this problem greatly and really struggle to get the bushes in. Have you thought about a process called Zinc Spraying, there are 2 types, 1 gives a coating with a protective finish on top, the other can be sprayed over with paint etc.The only place I know that do it is a company in Dukinfield nr Manchester and it isnt cheap, but it is good, I can get you a telephone number if your interested.
Hi Chris, I hope this advise is of use to you. My son works for a 'high end' classic car restorer and I asked him what they would recommend. They have some very demanding customers and prepare cars to concours level.
First of all he says DONT get them shotblasted. Too much metal removal and too much risk of damage. That is the 'old fashioned' way which has been superseded. Get the parts acid stripped which will remove any rust and paint externally and, more importantly, internally. They use Ribble Technology at Preston who will acid dip and passivate. They have also done bits for me (for example the seat frames for my S1, alloy bodywork from a Lea Francis, suspension from a Celica GT4). The acid dipping process is relatively cheap and doesnt remove the metal!.
Passivating is only a short term protection and you need to have planned the next bit. You then have 3 choices;
1. If you dont want to use the car except for show (not a TVR then!)and you want it to last for ever, a few customers spec cadmium plating. But we wouldnt recommend it if there is to be winter use, it doesnt like salt. (As an aside, galvanising can also give rise to big problems if you use the car in the winter, under some circumstances zinc and salt are really bad news especially if the galavanised gets scratched it can eat in very quickly. They say DONT galvanise)
2. Next would be to use a good two pack etch primer, worth the small amount extra for a good primer. Paint the primer on the outside. Inject the inside, cover the holes and swill it around so all surfaces are covered. It is perfectly possible to do this well yourself. After the primer has set use a paint which is not going to chip, so dont use cellulose. A few choices; Hammerite is OK (suggested that it is better to use the smooth rather than the hammer finish for consistent depth of paint), you need to use the special thinners to get it to inject and wash around inside. It wouldnt be the favourite.
A second choice is a good two pack with extra plasticiser to reduce the chance of chipping, again it needs to be washed around inside.
Third choice, and it works perfectly well, is a domestic polyurethane (not a non drip because you couldnt inject that and get it to run around inside). The good domestic paints are remarkably resistant to chipping and scratching.
Whatever treatment you use, inject thinned down waxoyl and swill it around afterwards.
3. Get them plastic coated with the modern plastic. It is far better than it was and is what they would normally recommend. It is NOT however guaranteed to coat all the inside. You then need to do the etch priming inside, be careful not to get the etch primer onto the external plastic coating, it will etch itself on to the plastic (and dull the surface)! It is still a good idea to use a thinned domestic paint (white spirit thinner wont effect the plastic) swilled inside followed by waxoyl. Plastic coating is thick and will take quite deep scratching. One issue though with plastic coating is protecting critical dimensions and surfaces...if you dont want plastic coating on it then you have to cover it in something which will resist the coating process. For suspension bushes what they would recommend is that the bush rubber is burn out, gently! The outer sleeve of the bush is then carefully sawn through but the bush is not disturbed, it is then easy to remove the sleeve after coating leaving the bearing surface dimensionally correct.
What would I do? Definitely get them professionally acid dipped. Wash and dry well. Etch prime outside and swilled inside. Domestic black paint and a little white spirit swilled round inside. Polyurethane paint outside. Waxoyl inside, with a little thinners, with a little gentle warmth to help get it into the crevices. Check the polyurethane each spring and touch it up. Drive it!
First of all he says DONT get them shotblasted. Too much metal removal and too much risk of damage. That is the 'old fashioned' way which has been superseded. Get the parts acid stripped which will remove any rust and paint externally and, more importantly, internally. They use Ribble Technology at Preston who will acid dip and passivate. They have also done bits for me (for example the seat frames for my S1, alloy bodywork from a Lea Francis, suspension from a Celica GT4). The acid dipping process is relatively cheap and doesnt remove the metal!.
Passivating is only a short term protection and you need to have planned the next bit. You then have 3 choices;
1. If you dont want to use the car except for show (not a TVR then!)and you want it to last for ever, a few customers spec cadmium plating. But we wouldnt recommend it if there is to be winter use, it doesnt like salt. (As an aside, galvanising can also give rise to big problems if you use the car in the winter, under some circumstances zinc and salt are really bad news especially if the galavanised gets scratched it can eat in very quickly. They say DONT galvanise)
2. Next would be to use a good two pack etch primer, worth the small amount extra for a good primer. Paint the primer on the outside. Inject the inside, cover the holes and swill it around so all surfaces are covered. It is perfectly possible to do this well yourself. After the primer has set use a paint which is not going to chip, so dont use cellulose. A few choices; Hammerite is OK (suggested that it is better to use the smooth rather than the hammer finish for consistent depth of paint), you need to use the special thinners to get it to inject and wash around inside. It wouldnt be the favourite.
A second choice is a good two pack with extra plasticiser to reduce the chance of chipping, again it needs to be washed around inside.
Third choice, and it works perfectly well, is a domestic polyurethane (not a non drip because you couldnt inject that and get it to run around inside). The good domestic paints are remarkably resistant to chipping and scratching.
Whatever treatment you use, inject thinned down waxoyl and swill it around afterwards.
3. Get them plastic coated with the modern plastic. It is far better than it was and is what they would normally recommend. It is NOT however guaranteed to coat all the inside. You then need to do the etch priming inside, be careful not to get the etch primer onto the external plastic coating, it will etch itself on to the plastic (and dull the surface)! It is still a good idea to use a thinned domestic paint (white spirit thinner wont effect the plastic) swilled inside followed by waxoyl. Plastic coating is thick and will take quite deep scratching. One issue though with plastic coating is protecting critical dimensions and surfaces...if you dont want plastic coating on it then you have to cover it in something which will resist the coating process. For suspension bushes what they would recommend is that the bush rubber is burn out, gently! The outer sleeve of the bush is then carefully sawn through but the bush is not disturbed, it is then easy to remove the sleeve after coating leaving the bearing surface dimensionally correct.
What would I do? Definitely get them professionally acid dipped. Wash and dry well. Etch prime outside and swilled inside. Domestic black paint and a little white spirit swilled round inside. Polyurethane paint outside. Waxoyl inside, with a little thinners, with a little gentle warmth to help get it into the crevices. Check the polyurethane each spring and touch it up. Drive it!
I am not sure exactly what the passivating treatment is but it is a very limited but chemically etched on finish and you can effectively ignore it as far as subsequent treatment is concerned. It isnt a primer or anything like that, the metal will come back looking bare although when you study the surface you would realise that it is duller than would be expected for newly cleaned metal. All the passivating does is provide some chemical rather than physical protection from atmospheric moisture until the surface can be treated properly.
Hmmm, I suppose it is possible that some people use the term for other things but 'passivation' used as a scientific term would be chemical treatment only and certainly not a lacquer. Ribble Technology use the passivate treatment as part of the wash process after acid dipping to prevent what is sometimes termed as 'flash' light surface rusting. Anybody who has had steel sand or shot blasted knows it gets light surface rust very easily and quickly afterwards if not treated quickly, the same applies to acid dipping but is made worse in that the item has to be washed to get rid of the acid so unless it is passivated as part of the wash process there will be light surface rusting as it dries.
Thanks Ketvrin. Just found out a bit more. Spoke to Ribble Technology. The passivation treatment is iron phosphate, at molecular depth, intended to provide short term rust protection. This treatment happens to give a molecular structure which gives particularly good adhesion to paint and works very well with etch primers.
They indicated that the car restoration market has been a growing part of their business and they are adapting to cater for that market as a speciality. They surprised me by adding that they can get a complete TVR chassis in one of their tanks (and have done)and do it all in one go! (Damn....all those hours spent with power tools and dirty hair!). And remember their process does it inside as well as out.
Provided it is booked in, they could get the whole chassis turned round inside a day. Might well be worth a trailer trip!
(Their new, deeper, tank coming on line this year will do a Sierra Cosworth size whole shell!)
They are not geared up to do any paint finishing after passivation, that is for the customer to organise.
They are currently changing their web information and splitting into two sites, both under cosntruction at the moment but you may want to take a note of:
www.ribbletechnology.co.uk and www. paint-strip.co.uk
If you want to speak to the man who seems to know, contact John Sutton on 01772-202227 (mention you got the info from the forum).
(Chris, as this might now be of info for anybody doing any chassis restoration work, is it worth/possible setting this up as a search topic?)
They indicated that the car restoration market has been a growing part of their business and they are adapting to cater for that market as a speciality. They surprised me by adding that they can get a complete TVR chassis in one of their tanks (and have done)and do it all in one go! (Damn....all those hours spent with power tools and dirty hair!). And remember their process does it inside as well as out.
Provided it is booked in, they could get the whole chassis turned round inside a day. Might well be worth a trailer trip!
(Their new, deeper, tank coming on line this year will do a Sierra Cosworth size whole shell!)
They are not geared up to do any paint finishing after passivation, that is for the customer to organise.
They are currently changing their web information and splitting into two sites, both under cosntruction at the moment but you may want to take a note of:
www.ribbletechnology.co.uk and www. paint-strip.co.uk
If you want to speak to the man who seems to know, contact John Sutton on 01772-202227 (mention you got the info from the forum).
(Chris, as this might now be of info for anybody doing any chassis restoration work, is it worth/possible setting this up as a search topic?)
I read this with a sort of interest having worked on TVR's chassis for 30 years and I'm sure that the acid dipping of a chassis sounds great but.... having shot blasted/ repaired /shot blasted/ hot zinc sprayed/ etched/ primed and two part top coated ALL done in one work shop and built cars, perhaps 200+ cars in that time.
I cannot get my head around the almost automatic dismissal of shot blasting, the thought that every welded joint is slag free is foolish and that for me says that it won't work, the welding slag around joints is the riser for most chassis problems on ALL TVR's.
Adrian@
I cannot get my head around the almost automatic dismissal of shot blasting, the thought that every welded joint is slag free is foolish and that for me says that it won't work, the welding slag around joints is the riser for most chassis problems on ALL TVR's.
Adrian@
Edited by Adrian@ on Friday 25th January 19:23
My thoughts on this are simple - the blasters are about a mile from my house, Preston is about 130 miles away.
If it was close I'd consider an alternative, but I'm on a tight budget so I think I'll probably still end up blasting the chassis.
The thought of transporting a chassis 260 miles fills me with horror, and thats forgetting about the cost!
I haven't made my mind up on what to treat it with yet - though I'll be looking at what the blasters have to offer as they do various coatings.
Chris
If it was close I'd consider an alternative, but I'm on a tight budget so I think I'll probably still end up blasting the chassis.
The thought of transporting a chassis 260 miles fills me with horror, and thats forgetting about the cost!
I haven't made my mind up on what to treat it with yet - though I'll be looking at what the blasters have to offer as they do various coatings.
Chris
Edited by Barkychoc on Friday 25th January 18:21
Fair enough Chris, not sure where you are and whether there is an acid dip firm anywhere near you. Might be worth a check, it wasnt expensive.
Like Adrian (and he and I may be of a similar age!) I have had parts shotblasted for many years (I had parts for my Grantura Mk1 done about 35 years ago!) but since acid dip came available, and I saw the results, I havent had anything blast cleaned since. We even get light things like steel water pipes, thermostat housings, rocker covers etc dipped with really excellent results.
I suppose an important consideration for you would be whether there is rust inside as well as out? If it is inside a boxed section then blast cleaning often isnt effective. (On one occasion we ended up with a very heavy component; sand had got in, mixed with the gunge inside, and it had to be steam cleaned to get it out!)
Like Adrian (and he and I may be of a similar age!) I have had parts shotblasted for many years (I had parts for my Grantura Mk1 done about 35 years ago!) but since acid dip came available, and I saw the results, I havent had anything blast cleaned since. We even get light things like steel water pipes, thermostat housings, rocker covers etc dipped with really excellent results.
I suppose an important consideration for you would be whether there is rust inside as well as out? If it is inside a boxed section then blast cleaning often isnt effective. (On one occasion we ended up with a very heavy component; sand had got in, mixed with the gunge inside, and it had to be steam cleaned to get it out!)
greymrj said:
First of all he says DONT get them shotblasted. Too much metal removal and too much risk of damage. That is the 'old fashioned' way which has been superseded.
I really think they may be referring to bodyshells here rather than chassis or Trailing Arms which are a much thicker gauge of steel.I tend to agree with Adrian on this one, and to be honest if the steel on your trailing arms is so thin it would be damaged by shotblasting then I wouldnt be bothering powder coating them.
Is this the same process?
http://www.surfaceprocessing.co.uk/index.html
These guys are a more reasonable distance away.
Chris
http://www.surfaceprocessing.co.uk/index.html
These guys are a more reasonable distance away.
Chris
Gassing Station | S Series | Top of Page | What's New | My Stuff