Quick Old Chassis Question

[berni29]

Hello All Again

I have been looking at my original stripped chassis off of my 68 plus 2, and although it has a fair bit of surface rust it seems fine. Having said that it has not been subject to any stress for many many years (27000 mls). It is going to be shotblasted and zinc powder coated in the very near future. What should I do about the closed sections? I was thinking of drilling them and sloshing some rust converter in. Is that enough I wonder. I could try filling them up with hot waxoyl and draining it out. I will be very unhappy if the damn thing cracks after 6 months back on the road. My prevoius chassis (on my crashed car) had two beautiful cracks just before the turrets. Big ones.

Are there any parts of the chassis that give a really good indication of its true condition? I wonder if it can be weighed to work out how much metal it has lost?

You can see some pics of the chassis at the bottom of this page:
<a href='http://www.searchsmart.co.uk/lotus/2004_april.htm' target='_blank'>http://www.searchsmart.co.uk/lotus/2004_april.htm</a>

Many thanks

Berni

[khamai]

Care should be taken when zinc plating. The heat used has been know to cause distortion. Power coating may be a better solution. POR15 great for those sealed areas.

Comments from anyone else.

[type36lotus]

I have heard of concerns about powder coating areas that cannot be visually inspected. If the surface is breeched the rust will run under the plastic all the while wicking in more water. I had mine chemically stripped as that removes NO base metal. Then I sprayed it with a good anti-rust primer (I hope), then a top coat of chassis black.

Mike Geiger
66 S3 Coupe'

[steveww]

Looking through your pictures I noticed that the cam chain adjuster is screwed in a long way. If you are not rebuilding the engine I would suggest you at least have a good look at the timing gear.

[berni29]

Hello

Ooooooo good spot. I will definitely be giving it a once over. My brother is pretty good with engines, and mumbled something about helping.

I know exactly what you mean with powder coating. In my experience water nearly always gets underneath through cracks etc and then the powder coat just falls off the rusty underneath. My cousin has a powder coating business, and in fact the chassis has just gone off to him this morning. He said that it will not rust with this zinc coating on it. I have not had a proper talk with him yet about it. I must say that I am a bit skeptical. He did say that a colour coat goes in top of the zinc. Maybe I will have to put a flexible underseal on top of that!!

I have put a picture of the chassis hanging out of the back of a Volvo estate at
<a href='http://www.searchsmart.co.uk/lotus/2004_april.htm' target='_blank'>http://www.searchsmart.co.uk/lotus/2004_april.htm</a> for anyone who is interested in pictures of a lotus chassis hanging out of the backs of estate cars.

In fact I have a bit of a problem in that direction because I have bought a +2s chassis, sight unseen but it is 150 miles away. Apparently it is in useable condition and only cost ?75, plus getting it back home of course. I am looking for roof bars for my wifes Nissan Almera because I would rather drive that than the Volvo with tailgate open. And it will be better on petrol even with a chassis on the roof.

All the best

Berni

[rgh0]

The best way to protect an old chassis is to clean it by blasting, then spray paint with a couple of coats of inorganic zinc primer and then top coat with a couple of coats of alkyd enamel or powder coat. This is the sort of paint sytem used on things like off shore oil rigs on items they dont galvanise. I would never galvanise the Lotus Elan or plus 2 chassis ( either new or old) as it is to thin to do without distortion.

Inside the closed in front cross member something like waxoyl will limit corrossion. With the original chassis I would add a drain plug also ( like has been done by Spyder) so it can be drained of any fuel or water build up and retreated.

In the end all this unfortunately gives no guarrantee with an old chassis as hidden corossion or fatigue can still exist that cannot be detected, especially around the joins between the front towers and cross member.

Rohan
(Having replaced chassis on both the Elan and Plus 2 rather than take risks with an old chassis rebuild).

[berni29]

Rohan

I realllly wanted a spyder chassis, but the rebuild is (very unfortunately) on a shoestring budget. That is just the way it is. Time I can spend though.

I have seen on the internet that people do strengthen the chassis for racing. With mine I will just have to keep an eye on it. At least with it being clean any cracks should be spotable.

Apart from the front crossmember are any other sections closed? I will fillow your suggestion with the waxoyl and drain plug.

I will find out exactly what this zinc coating thing that I am having done is. It is either a wet paint or a powder layer I guess.

Many thanks for the help

Berni

[rgh0]

Berni

No other closed in sections except the front cross member. With an old chassis the front towers are worth closing in at the top behind the spring shocker unit and closing up the two small drain holes at the bottom (as has been done by Spyder).

Other areas to check with an old chassis include.

The engine and roll bar mount brackets tend to crack.

The suspension brackets at the top of the rear towers tend to bend, they can be reinforced by boxing in the top with a plate that has a cutout that still allows the lotocones to be fitted in place.

The 26R's has reinforcing where the front and rear Y sections joined the backbone, however I have never seen any major problems in road cars in this area.

The loads on the bolts welded into the chassis for the diff torque rods can produce in cracks in the chassis in this area and need reinforcing.

The differential top mounts can crack around their locating nuts especially with CV drive shafts and in the plus 2 it is worth reinforcing around these mounts.

The brackets that locate the indoard ends of the rear Suspension A frames can crack at the welds to the chassis.

The gear box mounting bracket can crack where it bolt to the chassis


If you look at the above list you see that nearly anything that moves that is connected to the chassis ( i.e. anything but the body) appears to be capable of producing cracking at its connection point. The only connection that Lotus over designed ( i.e. they dont fail after 30 years) appears to be the front suspension pivot bolts.


Check all these points during the rebuild and reinforce it possible..

Rohan