This page is a copy of the original page fund on LotusElan.net wiki page : Chassis Modifications. It is replicated in case some day the original one is not accessible.

The Elan chassis is a wonderful design. Even a wonderful design can be improved with 50 years of usage.

Suggested Modifications

AVO Chassis Modifications

Click images to enlarge

When you have a good reason to take the frame out from under your Elan, you may find it to be in relatively good condition. That makes it hard to justify purchasing a new Lotus frame or an after-market alternative. There are improvements you can make during the degreasing, sandblasting, paint/powder-coat and re-assembly process.

The B/W pictures were taken at Advanced Vehicle Operations - a vintage Lotus shop in El Segundo, CA, USA, during the 80s & 90s. They show the modifications Clay Vyzralek recommended for a street car frame. For competition vehicles, Clay added strips along the underside of the top engine bay flanges in a manner similar to #5, and added gussets between the top of those flanges and the rear side of the front strut towers.

If you intend on performing these modifications yourself, it is recommended not to use an oxy-acetylene torch, since the high temperatures will weaken surrounding metal.

It is quite common for the front cross member air reservoir to contain remnants of brake fluid or petrol. While welding, these can ignite and at a minimum, scare the hell out of you. Similar stories are told of other closed areas containing rust preventative petrochemicals. Proceed with caution.

A 12 gauge (2.66mm) panel welded to the underside of the front cross-member, where the jack is usually and erroneously - placed when lifting the front of the car. A tow loop may be welded to this plate. Many Elans have had their bump steer readjusted by moronic towing attempts from the big holes in the rack
Avo mods 2.jpg
A new, thicker 14 (1.9mm) gauge, inboard sway bar support tab added on each side (left picture not drilled through yet).
Avo mods 3.jpg
A 16 gauge (1.9mm) reinforcing pad spot welded to the aft side each engine mount, to alleviate the cracking that frequently occurs here (left picture not drilled through yet). Later models may have come from the factory with these.
14 gauge (1.9mm) reinforcing strips welded in along the whole length of the underside of the central frame, on both sides. The openings should be closed off in the front to prevent scooping up dirt and road debris. Note the differential torque rod mounting blocks, described in the next photo. This modification may require re-routing of the rigid brake line through the tunnel due to the position of the exhaust pipe. It is probably a good idea to drill some holes and spray a rust retardant in the closed areas.
The holes (early models) or stock welded-on differential torque rod studs (later models) replaced with drilled steel square stock through which longer standard bolts are installed to secure the torque rods
14 gauge (1.9mm) reinforcement pads welded, on each side, on the bottom side of the top flange of the arms forming the engine bay, just forward of the curved cross-member. This area often develops distortion and cracks
Avo mods 6.jpg
Reinforcement of the rear strut towers with a welded-on 14 gauge (1.9mm) plate on the aft side. Template for strengthening the rearmost two towers by welding in 14 gauge triangular gussets.
These "wings" are three point seat belt mounts, welded directly to the chassis. This was less expensive than having original style brackets fabricated
Replacement of the cross-member under the engine with one that is removable. The cross-member is a hollow rectangular tube with the ends filled with solid stock and drilled. Note the 14 gauge (1.9mm) reinforcing plates on the top side of the cross member anchoring points

Tony Thompson Chassis Modifications

Click images to enlarge

Ttr9.jpg Ttr10.jpg
Ttr11.jpg Ttr12.jpg
Ttr13.jpg