# What's the underside of your R32 GTR like?



## GTR_Cymru (Jun 28, 2005)

I'll show you mine if you show me yours!


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## K_arlstrom (Apr 17, 2016)

Before I completed the new fuel system installation, not perfect but will replace the frames next winter


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## kevr32 (Sep 24, 2009)

It's a work in progress, but I'm getting there, slowly.


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## mambastu (Feb 13, 2002)

Looked like this before I started:

















During the process:


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## mambastu (Feb 13, 2002)

After many hours:


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## mambastu (Feb 13, 2002)




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## r32gtrmike (Jul 7, 2016)

wow....that looks great


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## r32gtrmike (Jul 7, 2016)

Mine is nowhere near as nice as that!




Cat has since been removed and replaced with a Tomei decat.


Hicas has also been removed after this was taken.


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## GTR_Cymru (Jun 28, 2005)

Nice job Mambastu

What products have you used and who did the work?


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## markM3 (Jan 7, 2008)

As it was.

Underside refurb now completed since. Will get more pics from Bob at Zealou5 of if I get it on a ramp in future.


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## MattSky (Jan 15, 2016)

Wow, super clean! Mine is not like this, but instead covered in some kind of sealant (rubber type compound) to stop the rust from the UK roads.

Is it ok to use the car on UK roads without this?


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## markM3 (Jan 7, 2008)

Mine is protected.

All rust has been removed from the underside since those shots were taken (underseal stripped off, rust cut out, new metal welded in and then new underseal).

It has cost £000's, but confident I have one solid R32!


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## [email protected] (May 19, 2006)

mambastu said:


> Shiny underside pics


Wow shiny 

How did you get the gearbox like that, did you paint it?

If you polished it you have far more patience than me :chuckle:


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## mambastu (Feb 13, 2002)

GTR_Cymru said:


> Nice job Mambastu
> 
> What products have you used and who did the work?


Cheers  Hope this doesn't mire the thread but I've tried a number of different products over the years and I think I've found products that do seem to work now so hopefully this will help people save money. Certainly looking at the results 18 months on there is no rust at all on the underside and its working well.

I did all the work on it on a ramp at my bro-in-laws workshop. It was done mainly over the winter of 2014/15 which wasn't ideal as the temperature was around 0-8 degrees a lot of the time but it illustrates how good the paint and coatings cope with low temperatures. 

First of all it was a case of using a hot air gun and scrapers to scrape off the standard Nissan stonechip/underseal mainly used between the chassis rails and the sills. Also the standard seam sealer needs to come off because a lot of the rust can be found along the seams under the seam sealer. Shown here:









Once that was off it was a case of using a air powered finger sander, a wire wheel, 3M de-rusting wheels (accept no substitute !) and on the flatter areas a sanding disk on a grinder. Basically you're trying to find areas of rust creeping underneath the etch/primer that Nissan used on the underbody. This picture shows how many rust spots there were. Mostly hidden by the stone chip/sealer : 

















Once that was done I used POR15 Metal Ready on any bare steel and FE123 rust converter on the seams and pitted metal. The POR15 etches the metal and deals with any light corrosion and the FE123 is a rust converter that converts rust to a benign substance to stop it in its tracks. Good for use inside box sections and seams. It turns a purple sort of colour and looks like this when applied :


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## mambastu (Feb 13, 2002)

Once the bare metal was etched and any remaining rust was converted it was on to a very high content zinc paint. For this I used Bilt Hamber Electrox from a 1ltr sized can. Its great stuff. 93% zinc and the can is ridiculously heavy when you pick it up. You would need a couple of cans to do the underside and arches. I've used other Zinc primers in the past and this stuff seems to work much better on the testing I did with it. Two coats were applied and its a very matt looking grey as shown here :

















Once the zinc had dried I painted on two coats of Bilt Hamber 2 pack Epoxy Mastic paint. I have also used another 2 pack Epoxy paint called Epoxy 121 but I've found it doesn't go on as well, takes longer to dry and the finish isn't as good. I have used the black Epoxy 121 on the propshaft and some of the other matt black components as I already had it.
Once the two coats of BH Epoxy Mastic had dried I seam sealed every seem with Sikaflex 221 which is a general purpose adhesive seam sealer. Messy to put on and a horrible job.
Once that had dried I applied another two coats of the BH Epoxy mastic over the underbody and seam sealer. Which looked like this :

















At this point I should mention the right hand rear plastic vent which goes in this hole which is pretty hidden by the fuel tank normally. Its a major rust trap because the rubber flaps that cover the plastic vent panel fall out and/or shrink and the rear quarter fills up with water from the right hand rear wheel. The bottom three inches of the panel shown here had to be re-built completely. Bro-in-law stepped in at this point and welded in the panel and we then found a related hole in the back of the rear quarter which had rusted from the inside out which I made a panel for and welded in :









I was intending to leave the Epoxy finish unadulterated but I was worried about stone damage but at the same time I didn't want rust spreading without being able to see it so in the end I sprayed the entire underside with Bilt Hamber Dynax UC which is a clear underseal which comes in really large spray cans. Great stuff. If you build it up with several thin layers it remains clear so you can see see if any rust comes through and it can be removed with White spirit if necessary. In the end I used it over most of the powder coated suspension components too to give a bit of stone damage protection and prevent moisture rotting all the re-plated nuts and bolts.

Final process was to deal with the cavities and box sections (sills etc).
I could have used FE-123 again but Dinitrol sell a product called RC900 which comes in a handy spray can with a cavity wand. Thinner than FE-123 it penetrates seams superbly so all cavities had two coats of that. That was followed by two applications of Bilt Hamber Dynax S50 which is a superb cavity wax.

Hopefully it should last for another 25 years +


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## mambastu (Feb 13, 2002)

[email protected] said:


> Wow shiny
> 
> How did you get the gearbox like that, did you paint it?
> 
> If you polished it you have far more patience than me :chuckle:


Bugger polishing it...I'm not that keen ! I know some people more OCD than me vapour blast aluminium casings etc but I use a nice aluminium paint from Carplan which gives the look of freshly cast aluminium, protects against surface corrosion and is easy to use and touch up when it gets hit by rocks/badgers. Good against heat too so I've used it on inlet manifolds and throttle bodies and it stops corrosion appearing quickly.


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## [email protected] (May 19, 2006)

mambastu said:


> Bugger polishing it...I'm not that keen ! I know some people more OCD than me vapour blast aluminium casings etc but I use a nice aluminium paint from Carplan which gives the look of freshly cast aluminium, protects against surface corrosion and is easy to use and touch up when it gets hit by rocks/badgers. Good against heat too so I've used it on inlet manifolds and throttle bodies and it stops corrosion appearing quickly.


That's good to know, I'm the same & would rather have a painted finished as its so much easier to keep it looking pristine compared to polished surfaces especially if your car gets used a bit!

Will have to investigate that paint for mine, thanks.


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## GTR_Cymru (Jun 28, 2005)

Thanks for the information Stu (mambastu).

I've been speaking to Dinitrol this week, as I just want to preserve the underside of my BNR32 as it is (a look at the photos will tell you why) with some sort of clear coat.
I'm also going to see what Bobby Proctor at Zealou5 can offer.


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## mambastu (Feb 13, 2002)

GTR_Cymru said:


> Thanks for the information Stu (mambastu).
> 
> I've been speaking to Dinitrol this week, as I just want to preserve the underside of my BNR32 as it is (a look at the photos will tell you why) with some sort of clear coat.
> I'm also going to see what Bobby Proctor at Zealou5 can offer.


I was very pleased with the Dinitrol RC900 rust converter I used in the box sections and they do a similar clear underseal/preserver to the Bilt Hamber Dynax S50 I used. The good thing with the Bilt Hamber spray cans is that they are absolutely huge and you can do a large area with them which makes them pretty cost effective. The S50 can be used as a general weather protector and because its removable with white spirit it has other uses like using a thin coat to protect polished aluminium, coilover threads etc


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