Improving standard chassis to 26R spec or similar

[dunclentdr]

I have the opportunity to by a standard, new, steel chassis and wonder how it might be possible to upgrade it to 26R spec or similar. It is for a fast road/track car, not for racing, which may have a 26R body - a GTS or similar.

Does anyone have advice on what improvements to make, who may do it (in the UK) and how much the work might cost?

Thanks

David

[nomad]

Time consuming so I wouldn't expect it to come cheap and one has to be careful in a few places so that the welds don't warp things. IMO I would lean toward doing the work yourself or buying a chassis done correctly and selling the one you have. Just did mine myself.

Kurt
26/3754

[richardcox_lotus]

I'm accessing this site on a mobile at present so won't try and browse the searches but there is definetly a previous post on here about 26R mods in terms of chassis upgrades. You may be better off searching via Google using the terms '26r chassis ' and 'welding' and trawl through. The thread I recall has pictures including all welding supports and lightening holes and rustproofing.

Sorry I couldn't be more help

[pharriso]

This - http://www.lotuselan.net/wiki/Chassis_Modifications maybe?

[dunclentdr]

Great - thank you.

I think the lesson is that it is better to buy an already created 26R chassis than a standard one to convert.

I'm left wondering whether there is any real value of these modifications for a fast road/track day GTS-style car, other than the link to the 26R?

David

[stevebroad]

A good point. I went through the process of converting my chassis to 26R spec plus a few other stiffening mods. It was better but still like a stick of licorice when a corner was picked up (everything on except body). The problem is that the tiny box section in the middle can't deal with the bending moments created by the wheels.

There is not a lot that can be done, IMO, to improve this other than a full roll cage (preferably welded in) extending to the front towers. This is the route I went down, it added weight but the chassis is now pretty rigid so a lot more power can be used. Not for the purists, though

[Davidb]

I just did my chassis over the last few days-and it took a few days!
I had access to a shop (RWM just south of Vancouver) who let me do the grunt work but then Robert Maynard did the skill part-the welding.

I made the reinforcing strips with a bend at either side-using a brake-and Robert welded them using the outside edge of the chassis as a guide-this really strengthened the area around the rear suspension pickups. We also did the front of the chassis of course-but I didn't take photos yet. Also we reinforced the engine mounts, the sway bar mounts and I put gussets in the area above the diff. A lot of work!

imagehosting

image hosting websites
Of course, it would have been easier if the chassis wasn't stuck to the ceiling!
(Its the right way up in Picassa so I dunno what imagehosting is doing...)

[Certified Lotus]

I made the decision to purchase a new 26R chassis rather than modify mine as I had read many stories about the issues of warping during welding. Didn't want to chance it.

[Davidb]

It might also be worth bearing in mind that these are not really "26R" modifications-they are later modifications, developed, I understand, to keep the chassis together since they cracked and broke in heavy racing use . I first saw these mods in the early/mid eighties in California but they must have been done much earlier -as required...

[stevebroad]

It might also be worth bearing in mind that these are not really "26R" modifications-they are later modifications, developed, I understand, to keep the chassis together since they cracked and broke in heavy racing use . I first saw these mods in the early/mid eighties in California but they must have been done much earlier -as required...

Ah, if that is the case then it explains why a '26R' chassis still flexes. The mods are for structural strength rather than rigidity.

[rgh0]

I would consider most of the mods "optional" unless you like bouncing your Elan off the curbs on the track as some people do.

Probably the only essential one is the stiffening of the brackets that hold the strut tops for the rear suspension. These will bend with a stiff spring and shocker setup for the track, how fast depends on how rough your tracks and how stiff your suspension.

The rest of the mods described I have not found needed on a standard lotus replacement chassis I fitted in 1980 and have raced with since.

Maybe some reinforcing around the diff torque rods attachment points would be advisable as I have a small amount of distortion in that area though no cracking. They generally only crack if you don't keep the rods attached with the right conical nuts or washers and keep it tight. I have also seen plus 2 chassis also crack around the top diff mounts but never seen it in an Elan.

cheers
Rohan

[ecamiel]

the stock ?lan is very flexible particularly around the horizontal plane. Torsionally it is OK but not up to modern tires.
The chassis is really just a sub frame for mounting components. The body provides most of the stiffness. In the late 60's, before cages were allowed, some light weight racing Elans were forced by the rules to change to street weight bodies and found that they were faster with the heavier bodies.
Judicious application of unidirectional carbon fiber helps tremendously. A diagonal cross lamination under the floor solves the horizontal flexing. Add carbon fiber to the body leading to the suspension mounts.Tying together the and triangulating the front and rear suspension mounts helps further. This is a good solution for cars without a roll cage.
Don't forget that the Dash is also a structural member.

Eric
64 S1 Hart

[stevebroad]

Judicious application of unidirectional carbon fiber helps tremendously. A diagonal cross lamination under the floor solves the horizontal flexing. Add carbon fiber to the body leading to the suspension mounts.

Eric
64 S1 Hart

By horizontal flexing, do you mean front axle in relation to the rear?

[Davidb]

Eric, I am having trouble envisioning what you mean-any photos?

[el-saturn]

eric ----------- i love the idea of using cfrp - wouldn't we desire a wound body in a med. tensile thread using epoxy - I went th old fashioned way in 1981: a safety devices cage (no front screen bars!) HOWEVER the chassis i'd say is 4 times as stiff !!!!!!????????????? as it would be without ------------- and wound elan bodies could maybe be made of modified (highly!!) modified Beezer X1 bodies!! sandy