Rear Crossmember maintenance

[sussex]

In the next few weeks i will be protecting my rear crossmember from further corrosion or at least slow it down, i have given it a thorough check over from the top and below and it is in very good condition just a little surface rust on the welds, first step will be to clean off any surface rust and treat any rust areas with rust eater then paint the whole cross member with red oxide primer then top coat with smoothrite or something similar, i will also be injecting wax into the crossmember internally, i like Bilt Hamber protection waxes, just wondered what wax etc you guys have used in your crossmembers.

[1979scotte]

Wax isnt as good as you think.
Mine was waxoyled but the heat from the exhaust causes it to melt.
I think dinitrol has been suggested as a superior product.

[gazza1286]

I used the Dynax cavity wax

 m http://pages.ebay.com/link/?nav=item.vi ... 78&alt=web m  

The probe works very well and the rubber bungs on the rear sub-frame provide easy access. The 750ml can is more than enough to do the job. Leakage from the seams over the following weeks leaves a bit of a mess on the nappy but it just scrapes off. Not had any problems with the heat from the exhaust. I think I may have just put too much in.. It's all solidified now. Thoroughly recommend it.

[cabbydave]

What do you think about powder coating?

[sussex]

I also thought Dynax S50 would be my first choice and have used Bilt Hamber products in the past and was very impressed with quality, powder coating or nylon coating would be an excellent option, but i don't really want to remove the crossmember.

[sussex]

Does anyone leave any of the lower rubber bungs out to aid moisture drainage ? thought i had read it somewhere on here.

[Carolyn]

I've had dealings with three of these so far.  All of them pre-facelift.  Two have required welding. It's my observation that, in addition to the external surface rusting, they rot from the inside out, at the lowest point near the suspension mounts.  The wet gets in through the four open top corners and sits inside with no way out.  I've sealed those corners on all three that I've dealt with.  I don't know if this would apply to the later ones.  So, whatever else you do, I do think sealing the corners is a very good move.  the corners can be sealed with it in the car. A bit messy and fiddly but if you can keep the air and water out then it can't rust.

[sussex]

Hi Carolyn, Do you seal the corners with underseal or silicone etc.

[Carolyn]

Hi Carolyn, Do you seal the corners with underseal or silicone etc.

I used a a good silicone.  Washed them out with solvent (thinners, brake cleaner, or equivalent) first to help it stick.  I ended up putting on some rubber gloves and doing it with my finger.  When it had set, I gave it another go just to make sure there were no holes.

[Ardent]

I also thought Dynax S50 would be my first choice and have used Bilt Hamber products in the past and was very impressed with quality, powder coating or nylon coating would be an excellent option, but i don't really want to remove the crossmember.

I used the S50. Exactly as above, can plenty big enough, easy with the flexi tube and yes bit of leakage. Was toying with powder coating then just smooth hammerited it.

It may have been me that have read, I have left the bungs out.

Jase

[sussex]

Thanks all, Have ordered the Dynax S50, will seal the the four corner openings with silicone, will probably wait a few weeks until the weather settles down and warms up a bit.

[sussex]

This morning the sun was shining so decided to treat the internals of my rear crossmember to a full can of Bilt Hamber Dynax S50, removed the rubber plugs on the top of the crossmember and fed the supplied long tube into the crossmember, alternating between holes, used the whole 750ml aerosol can, put some old carpet under the car to catch any dripping s50 as there was some, will put the car on ramps tomorrow and treat/paint the underside of the crossmember with red oxide paint and then smoothrite as a top coat, also today removed the side vents and flushed/cleaned out the soft top drains, they were full of dirt/mud, didn't look like they had been done for a long time.   s8) s8)

[grog]

i'd advise against power coat, most places these days to not bake the power coat long enough, it looks fine, but can start to corrode between the powder coat and metal, this leads to faster corrosion,
also any stone chips in good powder coat can also let the moisture get in and creep along under the coating,
Dynax is a good idea to help prevent corrosion, and i would recommend a coat of POR15 it's an epoxy based 'super hammerite' you mix in a hardener then paint it on, it hardens then it's super tough, much more resilient than either powder coat or hammerite,
after the POR15 painting, i'd Dynax to get all the unreachable bits,

[sussex]

Problem is the crossmember corrodes from within,  no matter how robust the outside finish is the corrosion is internal, using a super tough plastic coating outside could mask whats happening inside, i also decided not to try and seal the crossmember as i think having openings at either end would at least keep air moving through the crossmember,i might remove the lower middle rubber plug which would aid drainage of condensation/ moisture, for me the critical part of the process is treating the inside, generally any exterior metal paint is ok for the outside as the crossmember is well protected from the elements by plastic nappy/ undertray.

[Fin]

Just a quickie... my new cross member is due tomorrow, so I can paint the outside over the weekend with a view to fitting next Tuesday.
Can the S50 be sprayed easily with it installed in the car? I think I am going to struggle to get any in time.

[Carolyn]

I'm afraid I have to disagree (in the most agreeable way possible) with Sussex's idea of not sealing the cross-member.  Here's the basic chemistry:

Rust (iron oxide) is formed in the presence of iron, water and oxygen. In a sealed environment any gaseous oxygen will quickly be bound up with a very small (microscopic) amount of iron (steel, in this case).  Once that has happened further oxidation (rust) cannot happen.

[deviantmr-s]

I have a new crossmember that has been powder coated as a starting point, and have been reading quite a lot of threads on here. I plan on treating the inside with possibly Jenolite and then S50 and sealing the bottom corners, but unsure what would be best to coat the outer - as there are many varying options and opinions that I have read. Advice/guidance would be helpful of the best solutions. Also I have read of possibly wrapping the exhaust or a bespoke heat shield?

[Bossworld]

I've coated my brand new one from Toyota with two layers of Hammerite.  Bought another for mum earlier in the week, it's one of the Toyota replacements (black rather than silver) and although it's been on a car previously it's near immaculature.  Not sure if Toyota upped their game with the replacements?

Either way I've given this one a thick coat of Hammerite and covered 2/3rds of it with protection wax (also spraying through the four holes where possible), will do the underside later before it goes on her car at the weekend.  May get the silicon sealant out while I've got the chance although didn't do that to mine admittedly.

[jonbill]

I just liberally coated mine inside and out with waxoyl underseal. I've used that for years on my cars that don't go out in the winter and they haven't rusted at all yet [emoji16]

[deviantmr-s]

I have just read an snippet sent to me via another member - which is interesting...

A new imitator is using a rust converter before applying a rustproofing wax. This is why you should beware rust converters:

First of all, the underneath of most cars, especially Land Rovers, is contaminated with oil and grease from leaking oil seals etc. Unless the underside is extremely thoroughly cleaned, degreased, and then completely dried, the rust converter will not work. (Waxoyl is chemically very similar to oil and grease and will penetrate through it and form an amalgam with it). So you are very likely to have the nightmare scenario of an ineffective, poorly adhering coating sitting between the rusty surface and any coating of Rustproofing wax, making the Rustproofing wax totally ineffectual.

Rust converters contain a latex co-polymer. The rust converters are not penetrative. Try this test: Get a rusty panel and coat it with the rust converter. The converter will turn the rusty area an impressive rust blue/black colour. Once the converter has done its work, take something sharp like a flat bladed screwdriver and score through the area that has been converted. You will usually see unconverted red rust underneath the blue/black stuff. A coating of waxoyl/dinitrol etc over the area which has been converted will not penetrate into the converter because it contains a latex copolymer. Rustproofing waxes/oils/greases contain rust inhibitors and the wax etc. needs to be in contact with the metal's surface to work properly. So the Rustproofing wax applied over the rust converter is of very little use. The wax/converter coating is only as good as the performance of the converter, which, as we have seen is not good. This means that in a matter of a few months or at most a year, the wax/converter coating will fail and rust will appear through the coating.

Waxoyl is infinitely better at killing rust than rust converters. The rust converter plus waxoyl may appear at first sight like "belt and braces" but the fact is that the rust converter will ruin the whole job.

[The Other Stu]

Surely then that means give it a good wirebrush if not a bit of sanding first?
I wirebrushed mine anyway, because it had a little light surface rust.

[Gaz mr-s]

Of relevance to the inside.

[deviantmr-s]

I believe of relevance to both inside and out...   s:D s:D

[Essex2Visuvesi]

Any reason why it cannot be galvanised?

[Carolyn]

It's painted inside and out.  Would have to be chemically stripped.