Lotus Elan

Does a TTR 26R chassis need further strengthening?

PostPost by: 661 » Thu Jul 14, 2016 12:45 pm

As above really. I have a new TTR 26R chassis. I intend to use it for racing. The chassis has what I would consider to be all the 'usual' reinforcements. Is there anything else I should consider doing to it before sending off to the powder coater?
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PostPost by: toomspj » Thu Jul 14, 2016 3:01 pm

I can give a couple of pointers

First, I'd make sure it fits the body shell - they're not always compatible and then I'd drill the major mounting points and tap threads where appropriate.

There are two areas in particular where I'd do some extra work - the first is the engine mountings where I would weld on some 3/8" UNF (you could use 5/16") nuts on the backside - makes installing and removing engines so much easier.

The second is the rear mounting holes for the chassis on the rear turrets. This where the roll over bar attaches and also where the seatbelt pick up point is. FIA and MSA now seem to require the bolt to pass right through the chassis and be secured by a nut on the back side. (TTR sell the mounting kit) To this end, I'd install a tube (minimum 3/8" preferably 7/16" id) to allow the bolt to be securely tightened without crushing the turret.

So far as I can remember the rest of the chassis is good and I haven't had any failures on mine.

Also if you're planning to race it, I think it's better to paint with two pack paint (don't bother with lacquer) than powder coat as it makes touch ups and repairs so much easier. I do accept that the finish is not so durable and does rub off if you go in the kitty litter.

Hope that helps

Paul
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PostPost by: 661 » Thu Jul 14, 2016 10:48 pm

Thanks Paul, that's very interesting.
I think I can live with the engine mounts but the rear turret mount is new to me. I guess an aluminium tube spacer to fit could be added at a later date.
Is there a definitive 'thou shalt' FIA list? ( this is a slight thread drift!)
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PostPost by: Elan45 » Fri Jul 15, 2016 12:36 pm

Probably too late to register, but I agree w/ Paul about welding in a tube in the rear strut for the mounting. MMuch stronger! I also agree w/ 2-pac paint as opposed to powder coat. I do disagree w/ him on durability of powder coat. One scratch in the PC and it will fail It seems to not bond to the steel and eventually will peal off w. lots of rust underneath it.
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PostPost by: Bud English » Fri Jul 15, 2016 2:52 pm

Elan45 wrote:I do disagree w/ him on durability of powder coat. One scratch in the PC and it will fail It seems to not bond to the steel and eventually will peal off w. lots of rust underneath it.

I'd strongly second that opinion after just replacing 160 feet of rusted out, powder coated, sub frame tubing on my older motorhome. They have improved the durability over the years but I still wouldn't trust it where it will be subject to scratching and rock chips. One chip and the water/rust run under the coating further lifting the coating and exposing the metal. A good paint job does a much better job IMHP.

Powder coating wasn't developed to be a superior finish, but to provide a finish process that would comply to ever tightening air quality regulations faced by manufacturers and lower costs (go figure). A little history here:
http://www.cggc.duke.edu/pdfs/Brun_Goli ... option.pdf
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PostPost by: toomspj » Fri Jul 15, 2016 5:16 pm

You can live with the engine mounts without nuts welded on - I have that situation on my current car/chassis. But, if you race the car, the engine is in and out like a yo-yo (clutch, gearbox, exhaust, engine, access to chassis). And life is so much easier if you don't have to try and wedge a spanner on the backside with an exhaust manifold that has got pushed up against it.

As for alloy tube in the rear turret - you probably could do that but a thin walled steel tube would be much easier and if done before painting it would be straightforward. Downside is that you have to fit it to body first.

I guess i was being generous to the powder coating durability. I never use it on race cars for the reasons the other guys have stated - once breached you don't know what corrosion is going on until too late.

Oh, one other thing. Make sure the gearbox mounting has 4 captive (5/6" UNF) nuts welded on. I think most of the Gartrac chassis come with them. If not, you'll be cursing when you need to drop the box - again, it's possible without if you have special thin spanners but a complete and utter pain!

Good luck,

Paul
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PostPost by: 661 » Sat Jul 16, 2016 10:23 am

Thank you all.
Paul, I see your point regarding the engine mounts, I'll weld on some captive 3/8 UNFs .
The project presently is to make a rolling chassis and I don't have the bodyshell. I'll therefore have to cross the rear turret issue at a later stage.
This business about the paint has really unsettled me.
Plan A was to POR15 it , but with time and reading I've gone over to PC. I've spoke to various manufacturers and technical advisors. The consensus seems to be a 3 coat system. Zinc etch primer, epoxy primer, polyester top coat.
With 2 pack it would be wet applied and would be difficult to get into those difficult to access box sections. What primer did you use? I understand the ease with which you could touch up repairs.
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PostPost by: Elan45 » Sat Jul 16, 2016 4:02 pm

Ditzler (PPG corp) DP40/ DP401. Great stuff. I've been using it for over 30 years on my Elans, my Eleven, my Falcon bodied Austin Healey Sprite and my Lotus 20/22. It has been re-fornulated over the years as it used to mix 50-50, now is some other proportion. I believe Ditzler are now recommending it on fiberglass.

Roger
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'70 Elan +2S RHD
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PostPost by: dunclentdr » Sat Jul 16, 2016 4:31 pm

TTR offer a service to coat the chassis with stove enamel paint - what views and experience do people have of that solution?

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PostPost by: stevebroad » Sat Jul 16, 2016 6:26 pm

When I got my chassis back from being modified to above 26R spec, I rust treated the bare metal bits then gave it two coats of Frost's Extreme Chassis Black:

http://www.frost.co.uk/automotive-paint ... -397g.html

When it came time to weld in the roll cage we tried to clean it off with a drill driven wire brush but it wouldn't touch it. Had to resort to paint stripper and even this took at least two applications. Amazing stuff, IMO.

The roll cage will be getting a couple of coats.
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PostPost by: batfish » Tue Jul 19, 2016 4:24 pm

Regarding fia specs, adjustable spring platforms are definately not allowed when applying for new papers

Regards andy
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PostPost by: 661 » Wed Jul 20, 2016 8:11 pm

batfish wrote:Regarding fia specs, adjustable spring platforms are definately not allowed when applying for new papers

Regards andy

Thanks Andy,
I've been following this. I'm sure the inventive mind will find a way around this.
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PostPost by: toomspj » Wed Jul 20, 2016 9:41 pm

Hi Andy

What's adjustable spring platforms got to do with this post?

But since we're off topic, my experience is that most race series will allow adjustable platforms. You are right that to get FIA papers you will need fixed platforms which is fairly easy to achieve - just a bit of buggering (I think I can use that word as not in US dictionary -I'm sure Wickey will advise) about.

I've also been told by an eligibility scrutiniser that holes in perspex windows aren't allowed as they weren't homologated - even though people drilled holes in everything in period!
Strange times we live in.
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PostPost by: batfish » Mon Jul 25, 2016 3:54 pm

Paul

In the previous posts Graeme ''asked Is there a definitive 'thou shalt' FIA list? ( this is a slight thread drift!)'' and so I answered him

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PostPost by: 661 » Mon Jul 25, 2016 6:54 pm

batfish wrote:Paul

In the previous posts Graeme ''asked Is there a definitive 'thou shalt' FIA list? ( this is a slight thread drift!)'' and so I answered him

Andy


No harm in a bit of drift. I need to soak up as much information as possible. Thanks to all contributors.
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