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Old 28th September 2020, 13:11   #1
Pueblo_Boy
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Unhappy Sub-frame corrosion

I had an advisory for sub-frame corrosion, and paid someone to rub down the rear frame and apply rust remover. I still got an advisory at the next MOT - "corroded but structural rigidity not significantly reduced"

Recently, I saw a refurbished (4 coats of primer paint) sub-frame for sale at £80, and was tempted to buy it. My question is, what else would I need to buy and replace to make the job worthwhile? Bushes...new suspension arms for sure...what else and how much?

I also have an almost complete old rear sub-frame that I bought two years ago, because I wanted the upper arms off it (I used one). Presumably, this can this be sand-blasted and painted up...or alternatively, my existing sub-frame(s) could be removed and treated to sand-blasting and probably new bushes etc. too.

The MOT mentions both front and rear sub-frames, even though the front was apparently done some years ago. It makes sense I guess to have them both done, but at what cost? I would at the same time get the car underside rustproofed to protect the investment.

All of this will no doubt cost a pretty penny, though I have no idea how much - anybody care to estimate the costs? Or with 156,000 miles on the clock, should I be thinking of selling and investing in one with fewer rust issues? I really like my Tourer, and have made a number of improvements to it, but realise I could easily throw lots more money at it for little return in longevity... Please note I do not have the facility to do any mechanical work myself.

Any sage advice gratefully received.
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Old 28th September 2020, 20:04   #2
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Quote.--paid someone to rub down the rear frame and apply rust remover.


After that use spray on underseal.---Leaving it with just Rust Remover will make it rust 10 times faster than when new.---


Mine. Last MOT--advisory, Surface rust to sub frame.

This MOT, not a mention as I'd cleaned and undersealed the frame.---
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Old 29th September 2020, 00:30   #3
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[QUOTE=COLVERT;2839278]Quote.--paid someone to rub down the rear frame and apply rust remover.


[SIZE=3][COLOR=blue]After that use spray on underseal.---Leaving it with just Rust Remover will make it rust 10 times faster than when new.---[/

OMG! No mention of that effect on the tin... Should be called "Morust" instead of "Kurust"!

Ah well, I guess it's either expensive new subframes plus underseal, or a new car...which is why I need to work out the relevant costs to help make the decision.
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Old 29th September 2020, 07:33   #4
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A member had their sub frame shot blasted, primed and painted. I don't think manually rubbing down will do a good job unless you have load and loads of patience.

I would go the shot blast and spray paint method.

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Old 29th September 2020, 07:54   #5
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Quote:
Originally Posted by macafee2 View Post
A member had their sub frame shot blasted, primed and painted. I don't think manually rubbing down will do a good job unless you have load and loads of patience.

I would go the shot blast and spray paint method.

macafee2
Yes, I recall Marinabrian fixed up his father's car, spending many man-hours doing an absolutely terrific job on the sub-frame. But even he said he wouldn't want to do it again!

Therein lies the dilemma. The labour to remove the rear sub-frame, the cost of sandblasting and then painting several coats, then re-assembly, including new bushes as a minimum, is going to be not far shy of what, £500 from a garage? Increase that for the front sub-frame, and you're spending as much as the car is worth in the market...then underseal whilst you're at it!

Still, if it adds several years onto the life of the car, averaging out the cost over those extra years might justify the spend - at least in your head!

I've spent hours combing the used car markets looking for a replacement car I could live with, if I had to replace my Tourer. Nothing really compares in terms of value for money...nothing!
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Old 29th September 2020, 08:41   #6
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If the rust is mainly surface and not serious then a good make of spray-on underseal will stop any further rust in its tracks.

As I said in a previous post most spray-on underseals are quite runny before semi-hardening. They should run into all those nasty little crevices that are hard to get to.---
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Old 29th September 2020, 09:16   #7
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Quote:
Originally Posted by Pueblo_Boy View Post
Yes, I recall Marinabrian fixed up his father's car, spending many man-hours doing an absolutely terrific job on the sub-frame. But even he said he wouldn't want to do it again!

Therein lies the dilemma. The labour to remove the rear sub-frame, the cost of sandblasting and then painting several coats, then re-assembly, including new bushes as a minimum, is going to be not far shy of what, £500 from a garage? Increase that for the front sub-frame, and you're spending as much as the car is worth in the market...then underseal whilst you're at it!

Still, if it adds several years onto the life of the car, averaging out the cost over those extra years might justify the spend - at least in your head!

I've spent hours combing the used car markets looking for a replacement car I could live with, if I had to replace my Tourer. Nothing really compares in terms of value for money...nothing!
Are you able to remove and refit the sub frames. The front is heavy but the rear one is not, some "special" tools required and particularly with the rear, you may spot other surface rust spots on the body to deal with at the same time. It is not a hard job to remove and refit. I think Blink may have had a sub frame shot blasted and painted, someone has as I saw a post about it.

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Old 29th September 2020, 10:49   #8
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I don't have the facility to do much mechanical work on the car. Or any at all, for that matter! I wouldn't have the patience either!

Astraeus has done a few jobs for me in the past, but he's a bit tied up at the moment. Besides, taking off the sub-frame is best done with the car on a proper ramp, rather than crawling around on the floor methinks...

I have a fair few other jobs to do on the car, most of them straightforward - new rubber door surround attachment, change pollen and air filters, attach new side indicator lamps and set up a tyre pressure monitor system, plus silicon protective strip around the wheels, fix the driver's seat electrics and solve the airbag warning light etc. All basic diy jobs I would rather someone else did, rather than me doing a bodge job!
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Old 29th September 2020, 11:47   #9
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Is the subframe badly corroded? Or is it the arms they refer too? My own MOT tester mentioned subframe (and I have read of others being advisories with the same), but it was nowhere near the corrosion of the arms themselves. So imagine if the frame is corroded, the arms will be closer to failure than the subframe (unless they have been previously replaced).

I replaced subframe with new, when I saw a hole in my upper arms. I had the arms already. Bought new springs and shocks. Painted everything, and built it up on the ground and fitted myself with a trolley jack. Someone who knows what they are doing I imagine could do this in a few hours - it took me roughly a day, 6 days in total though, with painting and underseal etc. No special tools were needed for the rear (an electric impact gun helped with shock and arm bolts).

The old subframe though was still solid, lots of surface rust, so had it sandblasted and primed which cost £80 - therefore the one you have seen, seems like a bargain.

If it was me, I would get new arms, consider new bolts, springs and shocks (warning, new nuts and bolts are around £70-80 on their own!).

It was worth it, as I have peace of mind over it, but ultimately, I only needed to have the arms replaced, and I suspect the MOT tester was suggesting the arms were part of the actual subframe.
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Old 29th September 2020, 18:01   #10
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I'm in the process of removing my front subframe and intend to get it dipped to remove all rust inside and out. It will then be primed and baked. (The rear was too far gone so had to be replaced)
Not sure if anyone as any experience of this but I'll let you know how it turns out. It's not particularly cheap, but a lot cheaper than a new subframe, even allowing for new bushes.
When it comes back I'll coat outside in chassis paint and inside with cavity wax so hopefully should last a few years.
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