rusty chasis - problem or not?

[andyvicarage]

Hi I am new to this. I am looking to buy my first caterham. I am told that rust forms under the powder coating on the chasis where the coating inevitably gets damaged through stone chips etc. This is made much worse through winter use with salt on the roads. Small areas can be treated locally, but large or significant areas may require a partial strip down, or at worst a full strip down, sand blast and respray, or even a new chasis. I am also told by someone at caterham themselves that you shouldnt worry too much about it, as all cars get rusty, and (apart from 30 year old cars plus), they have never heard of any rusting that has got so bad as to affect the structural integrity of the car - it is just a cosmetic issue in cars up to about 20 years.

I would appreciate any opinions.

 

Edited by - andyvicarage on 6 Oct 2010 19:27:49

 

Edited by - andyvicarage on 6 Oct 2010 19:29:10

[k.russell]

I have seen pictures posted on here that show that some of the tubes have been totally eaten away at their junctions due to rust and salt erosion, should be lots of threads in the archive. search for grot trap, this is usually the first place to show any problems. you will see this on the very bottom of the sideskins just forward of the windscreen. it is where grot and salt can lodge between the inner footwells and the outer skin and chassis.

 

Kevin R

 

black(but sometimes orange)-ali HPC

here

[DJ.]

you will see this on the very bottom of the sideskins just forward of the windscreen. it is where grot and salt can lodge between the inner footwells and the outer skin and chassis

 

It amazes me that this area isn't blanked off when Caterham build the cars. I've seen some good tips on how to prevent this on Blatchat, and plan to copy them when my chassis arrives

[Midas]

I asked a similar number of questions of the chassis makers at Arch when I was there having a reskin. Thier experience is that for the vast majority of cases it is surface rust that has taken hold as the powder coating has flaked away.

 

The powder coating has gone through various phases of 'robustness' with the worst period seeming to be about 1999-2001ish.

 

On the other hand if the car has seen extensive wear and use, and lived outside throughout the year I have seen occasionally rusted tubes that need replacing. But I content this is quite rare.

 

Most cars are cared for by their owners and looked after. I think you would be very unlucky to find a car with serious rust unless it is a barn find or the most reckless owner.

 

FWIW I derust and piant the chassis each year as a 'service item'. No proble, I just like a car that is a shiny underneath as on top 😬

[SLR No.77]

The powder coating has gone through various phases of 'robustness' with the worst period seeming to be about 1999-2001ish.

A search will show up that this time period varies wildly - some say the dodgy powder coating years were 95/96, or 97/98, or whatever. Differs massively from car to car. I've had a '95 and it was fine. I now have a '99 and it's a little more corroded but it's had a harder life. Quite simply don't expect to use one in the winter months without doing some preventative maintenance!

 

There's some pictures I took whilst mine had the interior panels out, here - '99 chassis. Whilst in bits I added plenty of rust prevention!

 

Stu.

 

---

Joint Area Representative MAD Sevens (Merseyside And District)

www.superse7ens.co.uk..........the rebuild 😬

 

Edited by - sforshaw on 6 Oct 2010 22:36:50

[glasgow]

I derust and piant the chassis each year as a 'service item'. No proble, I just like a car that is a shiny underneath as on top

 

Midas, I am interested in what you said about derusting and chassis painting. How do you do this please?

[Mick Day]

When I stripped my 1994 chassis down in 2006 it was surprisingly sound under the powder coating that was flaking off. However I've owned my car from new & it doesn't really go out in the rain or get used much in the winter.

[pete east]

Arch chassis frames are extremely well made (in some respects a work of art,) but a seven is not made or protected from corossion in the same way as a mass produced tin top. They last well, especially when not used regularly on wet / icy / salted roads. (and for those that do use them this way, its worth cleaning and drying them off after every run) but bear in mind that some of the tubes are very thin walled (such that they can even be punctured by a stone) so regular checking for rust is quite important, especially where the car is used in wet / winter conditions.

As posted several times before I have seen sevens which looked immaculate from the top, but a corroded mess, when viewed from underneath.

As those people who bought series 4 Lotus sevens (thinking they were like a sprite/midget/spitfire etc type sportscar), found out to their cost, sevens are not like mass produced cars, and are normally owned by people who expect to get their hands dirty looking after them, every now and then.

[BenF]

My understanding was that cars from 94-99 were worst affected by lack of surface treatment before powdercoating.

 

When I was buying, I saw a couple of cars from this era which looked quite poor underneath. However, I am sure there are still good examples around, it's just a question of properly checking underneath.

 

If you're going to look at a car, post on BC beforehand as there's always a chance that an experienced 7 owner will be happy to come along.

[glasgow]

bear in mind that some of the tubes are very thin walled (such that they can even be punctured by a stone) so regular checking for rust is quite important,

 

Pete, How would you check for tust? would it be enough to left the 7 on axle stands?

[Eugene]

A lot of the comments here seem to be not at all accurate.

 

I have stripped many 7s and have never found a tube that is so thin it can be punctured by a stone.

 

Also, the alloy skin of the 7 acts as a sacrificial anode to the steel of the chassis, so any rot on the chassis will almost inevitably be preceded by bubbling bodywork.

 

I have had my 7 for well over 20 years and have had it re-chassied once, after an accident. It is used in all weathers, and while it looks 'used' there has never been a rot problem with the chassis, although the bodywork has suffered at times.

 

I do waxoil all areas, even between the double skin, to prevent the alloy sacrificing itself, but I have never had chassis rot problems, even though I do have 'rust' on some chassis and suspension components.

 

I've had a lot more rot problems on similar aged 'normal' cars... chassis rot on a 7 is very rare, unless you are called Dikko and have had a 7 for more years than you want to admit to, and never looked after it 😬

 

Small Boy - with Loud Toy!

Co-founder of the BOG Club

See Eugene here

and see what I do here

 

[I reply to every thread]

As Eugene says electrolytic corrosion is usually evident on a car that's rusty.

 

Let's not get this out of perspective - As long as the car looks relatively clean above and below and isn't driven by a salivating walrus with a salt water fording habit it is unlikely that chassis corrosion will be a real problem.

 

Many cars have some flaking powdercoat that can be corrected by a few hours with a tin of POR15 and the grot trap is easily dealt with by librally spraying Dinitrol into the gap and then sealing it up to prevent the worst crud getting in there.

 

To the OP I'd say that the summary given to you by Caterham is about right.

 

I've hung around here for 10 years odd and I can't recollect many "Oh no - I've bought a rusty puppy/shed" threads

[pete east]

As I dont use my car in wet weather, so the chassis is in good general condition, but I can assure you that some of the tubes ARE thin enough to be punctured by a stone.

How do I know this? because I had to dig a stone out of one of the circular chassis tubes, where it deeply embedded itself in the tube. No rust whatsoever on the tube in question, just bright metal around the hole left in the tube. which I then had to weld up.

 

Checking for rust means generally means checking that the powder coating is sound, Some of it can `look' Ok but give it a tap, and large sections can be found to be loose, and just falls off. Where this happens I just sand back the rust, and give the section a coat of Hammerite which seems to last OK.

 

Like I said before I have seen a number of sevens which looked great from the top immaculate even, but were a corroded mess underneath.

[MartinWoodham]

ref the grot trap, my car is a 2004 reg ie delivered in nov 2003, and the grot trap is blanked off with an ali strip and plenty silicone mastic. I'd presume all later cars will be the same?

 

Martin

supersported ex-Roadsports B

[Eugene]

Blanking off the grot trap is not always a good idea as it will still allow ingress of crap, and if it can't then exit it will hold damp and allow corosion... best to flood with waxoil on a regular basis and allow to breath.

 

Works for me

 

As for a tube being punctured by a stone - that stone had to be travelling at some speed! Bugger, that's unusual!

 

Small Boy - with Loud Toy!

Co-founder of the BOG Club

See Eugene here

and see what I do here

 

[Racing Snake]

Dont use in Jan & Feb when the salt is down

 

---

Mad Hatter The Dura Mentalist 😬 Carl @ Penn 7's Caution - May Contain Nuts !

[glasgow]

Dont use in Jan & Feb when the salt is down

 

Lucky you...... for me it is Nov to March

[Eugene]

Nah, use all year round, but keep well waxoiled...

 

😬

 

Small Boy - with Loud Toy!

Co-founder of the BOG Club

See Eugene here

and see what I do here

 

[virden]

Do not be over confident as to the sealing abilities if silicon mastic. I have found perfect looking seals hiding areas where the adhesion has failed. Always have avery cloe lok/prod.

 

I agree with the point about letting sealed areas breath, removable gromits do the job.

[pete east]

Eugene...Regarding the speed of the stone, I couldnt possibly say what speeds I `might' have been travelling at! 😬

You are spot on regarding closing off areas and creating sealed boxed areas not being a good idea, keeping areas open and able to `breathe' is definately the best way forward. I use a thin plastic tube taped into the pipe on the vacuum cleaner, to suck out the crud which can build up on the chassis rail, between the footwells, and outer side skin of the body, then give the general area a shot of waxoil. one thing that seems to work reaonably is take a small length of the neoprene wing seal strip, and araldite it to the side skin just ahead of the grot traps, this seems to keep most of the crud out, but still leaves the area visible, and accessible.

 

 

[caterhamnut]

Agree with what Aves and Eugene have said.

When we rebuilt our car (used all year, not polished, lived outside for ages etc etc) we had bits of the ali panels cracking away, turning to talc powder etc etc but I was pleasantly surprised at the condition of the metal tubing once it had been cleaned off. I think Bruce may have replaced one small section of the smallest section of tube near the 'grot trap' area, but overall it was fine - and ours was a 'bad' example (95 powder coating )

Things can look a lot worse cosmetically.

 

Angus's Adventures in Sevenland