Subframe replacement

[Colin McA]

I dont really have a project thread for my car so thought I would start a thread for my subframe replacement.

The Subframe has always been a weak point on my car and have managed to get away with it so far, however I can no longer delay the job.

The rear section was never good and the patch which had been welded has now rusted through, I could patch it up and keep motoring but having source a subframe about 5 years ago it is not going to get swapped unless I have an incentive (MoT expires on the 10th Aug) and I could do with the space back which the subframe has been hogging.

A few photos to begin.







Subframe stripped ready for Galvanising.











It took me about 2 years to source a decent subframe. This one was very good but I wanted to protect the inside as well as the outside which was why I opted to Galvanise it.

Moving the subframe about was one reason I bought a landrover defender too, the subframe fits nicely in the rear of a 110 station wagon when stripped.

Once Galvanised I left it in my garage whilst I found excuses to put the swap over off. It is a big job and I didnt want to have the car off the road and also other cars in my fleet needed TLC.

The plan is to neutralise the Glav and put a few coats of epoxy mastic on the subframe.

I have used products from rust.co.uk. I have brushed on SP10 and T -wash to half of the SF, it has started to turn black or rather dark grey. As it is a little awkward in the garage and I really need to rinse the SF off at various stages I decided to take it outside where it is now sitting on axle stands.

Hopefully progess will continue over the next few weeks.

I just need to order some new bushes as body mounts.

[Colin McA]

[petervdvelde]

Looks good!. What kind of treatment did it get before the galvanizing?. Did it get a chemical derust treatment or was it shotblasted. I drilled some holes in the subframe and sprayed some was in it. Might be good to do this also with your subframe although it got the galvanising treatment

Peter

[Colin McA]

I left it to the galvanisers.

They seem to blast it before dipping. I need to think about internal wax, I had thought about it.

I am thinking about putting some drain hole in particularly where the exhaust passes through as I have noticed that fluid is collecting here and this was the area my own SF has rotted out.

[petervdvelde]

I also drilled several holes to let moisture out. I would advise you to put some wax into the subframe. If there was rust inside the subframe, the galvanizing over the rust will not help much i believe but if there was rust and you spray wax over the rusted area's, the wax will kind of seal the rusted area's from moisture and stop it rusting further.
That said, the subframe of my project Coupe had several dents and i cut out several pieces, hammered out the dents and welded these steel pieces back on. During this proces i could look inside the subframe and found no rust but one cannot be sure your subframe doesn't have rust inside.
My car will live in a rather moisture free garage most of the time like many others so even without wax, it may outlive me but it is a rather easy task to spray some wax into the subframe if you have a loose subframe so it gives me a comfortable feeling to put some wax into the subframe

Peter

[Colin McA]

Did you leave the drain holes open or closed/plugged up?

I have left some of the dings, a way of identifying the car if needed.

[petervdvelde]

I left them open.

Peter

[petervdvelde]

Aug 8, 2017 9:59:44 GMT @dicky said:

. ; Whilst you can, make a note of the replacement frame serial number which is on there somewhere (front end from memory) as you might need to report it as an alteration. I think the frame carries the same number as the car body it was originally fitted to.

I think this is an important issue as there is no serial number stamped into the body. The number on the subframe is the sole number for identification of the car. If the number isn't identical to the car papers, you may get into trouble as you cannot change the serial number of the car. Maybe the DVLA offers a service to stamp in the original serial nr into the replacement subframe.

Peter

[Colin McA]

Not really an issue on pre 1980 cars.

[Colin McA]

flipped the SF over to get the underside.

There are some interesting patterns like the fern leaf which appeared on the tubes. Also some patches about the size on coins which are bright silver when all around is turning grey.

I reckon a few days of repeated application and rinsing cycles will be needed.

[Colin McA]

Some of the underside.

The Patch of black was where I brushed on some epoxy to check the adhesion a few weeks back. As you can see without neutralising the surface it doesnt stick well, as expected though. I did have to give it a good bit of a scrape to get it off but it flaked off once the surface had been broken.

Will need to keep up the cycles, the instructions werent really clear. It said when the surface turns black it is ready however i think it is just going to go a really dark grey.

[Colin McA]

Perhaps you arent aware of what I am aiming for here.

Lots of info in this website.

www.rust.co.uk/rust-proofing-paint-em121-epoxy-mastic/p404984

I am going to coat the SF in Epoxy mastic 121 it is what a lot of restorers are using now as the paints are old hat. Even at that any paint which claims to be a direct to or primer for galv will not be suitable considering the speed or the fluids which get on to the paint.

I have been researching this for a long time and this is what I feel is the best solution. I wanted the galv to get to the places a brush or nozzle wont reach but not have the appearance having driven over a bit of street furniture.

Once the surface has been neutalised I will put on a couple of coats of Black EM121 to give it the factory fresh look.

[Phil Nottingham]

Aug 9, 2017 18:53:33 GMT @dicky said:

I don't know how old you are, Colin but that galvanised frame will probably last about 100 years and all petrol vehicles will be gone by 2040  so why don't you use a primer undercoat for galvanised metal and then finish with a decent chassis black  Simple.

Remember only two people will ever see that sub frame in situ: you and the MOT inspector and even that might not be necessary when the government get around to announcing the 40 year rolling MOT exemption   

When I was as young as Colin I never thought about doing things on cars that might outlast me and even now I am redoing things I did over 30 years ago.   Now I do think who is going to benefit from making it last years!   Our annual motoring mileage continues to fall and will no doubt drop dramatically when I fully retire in the not now too distant future

[enigmas]

Not necessarily Phil....you just develop a new focus, such as doing road trips for enjoyment, because you can. Time is no longer a fixed deciding factor. For instance, I just arrived home from a road trip heading north to warmer climes travelling up the east coast of Australia. On average covering approx 450 kms each day from 9.30am - 3.30pm for 4 - 5 days each way with a 2 week stay in between, just stopping when we felt like it.

[Colin McA]

I removed the test sample.



Nice shiney bit below, as expected it flaked off when I chipped it as it wouldnt stick to untreated Galv.

Some of the slivers of silver where the zinc hasnt reacted as yet. I have a little more work before a coat of epoxy, this may take a week or so.

[Phil Nottingham]

What are you priming with?  Although I have not tried Land Rover owners always seem to use a Mordant Solution wash to, in effect, etch prime their new galvanised chassis although most do leave them to permanently weather. Even then some isolated corrosion has arisen on these after 10-15 years.  It is not standard on Land Rover chassis as with the P5 subframes just black chassis enamel


It is normally just watered down Potassium Aluminium Sulphate (Alum) but for Galvanising I think its Copper Sulphate and is not a coating so it cannot flake off. It is readily available from the paint suppliers etc like Johnsons.  It does, however, need a paint film for additional protection which will stick to unlike unweathered galvanising which will take up to 2 years before any coating will stay put.

I have painted galvanised garage doors with a paint type primer suitable of new galvanising and its always stayed on but any normal paint will harden and flake off over the years although Epoxies are not supposed to - they are not fully tested over time however

[Colin McA]

I am using the kit supplied from Rustbuster. www.rust.co.uk

The prep is using SP10 which cleans of some of the contaminants before the T wash which is a mordant solution. The label on this says it is an acid solution.

It seems to be working. It wont do any harm leaving it out side over a few weeks with sessions with the T-wash until it is ready.

[Colin McA]

The prep/weathering process continues so I thought best to get the required bushes ordered up. Decided to replace the isolators/mounts. I do have some serviceable but may as well replace.

Will need to go through the parts book and see what bolts are required, can guarantee some of them will be getting cut off.

[Colin McA]

Well almost a year on and I am still no further forward with the fitting.

Due to life getting in the way I missed my opportunity to get it ready for fitting.

A small bonus is it has endured a year of weathering,hopefully this will help the paint stick as the Mordent solution wasnt making a dent in the thick Galv.

Fingers crossed I can get it back on the road, a year without driving my P5 is criminal.