SE5 Chassis

Reliant Scimitar SE5 - Chassis

Mobirise

The chassis is a pretty rugged affair and the main rails don't seem to generally suffer major corrosion issues (probably due to the extra protection offered by that leaky old Essex up front). But there are a number of areas that this protective oil mist doesn't quite reach and so do suffer from corrosion.

For details on removing the body refer to the bodyshell section.

Initial Assessment

This particular chassis is in pretty good condition but it does exhibit a number of the usual symptoms commonly found.

Starting at the rear off-side (so that the photos flow in the correct order), here are some of the more common rust spots.

Fuel tank rail requires a small in-fill repair.

Outrigger is holed but not horrifically.

Common rust point at the rear of the suspension tube diagonal brace. The brace is an open face C section so creates a dirt trap. Replacement parts are available and the main chassis rail appears sound.

General view of the diagonal brace and another common rust spot, the seat belt mount.

A closer view showing the rusted seat belt mount. You can see that the top of the outer side rail has rusted through revealing the additional bracing in this area. The rusted remains of the body hoop fish plate is also visible.

Top of the front outrigger rusted through and further rust damage to the outer rail.

Near-side, starting at the forward out-rigger (or what's left of it).

Passenger side front outrigger is even worse.

The join between it and the outer side rail has all but disintegrated.

Passenger side seat belt mount was not as bad though.

The body hoop fishplate is sound on the passenger side so no rusted remains stuck to the end of the suspension tube.

The diagonal bracing has rusted though.

Datums!

Before chopping any metal out we need to preserve the datum positions of the main sections to be replaced. If the new outer rails are not located in the correct position the body will not fit back over them as they sit in a channel created by the recessed footwells and the outer sills.

A piece of box section steel (the small bit resting on the chassis, not the big bit lying alongside) salvaged from an old desk (or a bed would do, so long as it is straight) is laid across the chassis adjacent to the front outriggers.

Two pegs are welded to it at the correct distance...

... to align with the corners of the outrigger to side rail joints.
This is then tack welded to the main chassis rails.

The outer rail and front outrigger can then be cut from the chassis.

Both sides removed. Note another salvaged box section has been tack welded towards the rear. This is so that the new side rails can be positioned in line with the main rails.

Replacement Outer Rails

Replacement outer rails are available from the two major parts suppliers. However, as I am lowering the floor in my car and fitting additional outriggers for the seat rails to bolt to, I am making my own from deeper 60mm x 40mm full box-section (the originals are 'C' section).

The new outer rail box section is held up against the datum bars.

It is butted up against the suspension tube...

... and the centre of the tube is marked.

A pilot hole is drilled at this height, but about 4" along its length, all the way through both sides of the box section to ensure alignment. This is to give an overhang to the rear of the tube for a potential roll cage main hoop mounting.

A 63mm hole saw to match the diameter of the suspension mounting tube is used on each side of the box section at the pilot hole location.

The two cuts are joined curtesy of a cutting disc in the angry grinder.

Slotted into place. Note the overhang both front and rear.

A nice snug fit.

Replacement Front Outriggers

As with the outer rails, replacement outriggers are available from the two major parts suppliers. However, as I have made my own outer rails from deeper box section, I need to fabricate my own front outriggers to suite.

After taking a few key measurements a suitable piece of 1.5mm thick steel was cut.

Again taking suitable measurements the basic shape is folded.

The folder was bought second hand from a popular online auction site for circa £50.

Checking the fit over the outrigger support stub.

The new outer rail is put in place and with the outrigger placed against the main chassis rail...

... a line is drawn where the outer rail will meet the outrigger.

The depth of the outer rail is also marked against the outrigger.

the resultant notch it cut.

Trial fit. You will notice that the new part is as deep as the main chassis rail. This was a mistake, it should be deeper by enough to allow for a lower flange to be folded.

The outer rail is not against the datum peg. The outrigger requires further trimming to get the outer rail in the correct position.

Further trimming and trial fitting was carried out until a good fit was achieved.

The lower edges of the outrigger are trimmed off. In this shot I have trimmed too much off. I should have left more material to form a lower flange to give greater rigidity.

The lower flange needs to be folded before the notch for the outer rail is cut out. Otherwise it will twist in this area as it is folded.

Then the notch is cut out.

The inner end needs the flange relieving to clear the inner support stub.

In position fitting snuggly around the inner support stub.

Check for fit.

The location of the inner support stub is marked on the inside of the outrigger each side in felt pen.

This is transferred to the outer face each side.

A cardboard template is made of the each side of the support stub.

These are transferred to the outer faces of the outrigger using the first line as a guide to positioning.

The rest of the shape is transferred.

Replacement Center Outriggers

Due to the floor lowering the center outriggers need to be much shallower than the originals so again I am making my own.
The top of the steel box section I am using for the new seat rail mounting outriggers is 20mm tall.
The new outer rails are 60mm tall.
Therefore the centre outrigger needs to be lowered by 40mm so that it is in line with the new seat rail mounting outriggers.

The inner support stub will require a fair bit of trimming to allow the the new outrigger to sit in its new lower position. First a straight edge is set across the main and outer chassis rails.

The inner support stub is marked 50mm below this level. This allows clearance for both the thickness of the new outrigger and the bend radius of the sides.

Trimmed back with the trusty angry-grinder.

The new center outrigger blank is folded.

Check fit over the inner support stub.

A nice sliding fit over the inner support stub.

The main chassis rail needs to be clean so that it butts up against it.

The total required length is measured (to the outer edge of the outer rail).

Approx 530mm.

The side are trimmed allowing an overhang for the lower flange to be folded, remembering to allow extra depth at the outer rail end so that it passes under the outer rail.

Checking for fit before folding the lower flanges.

Lower flanges folded.

Rechecking the fit. The lower flanges will need light trimming at the main chassis rail end to clear the inner support stub.

Finally the outer rail notch is marked out and cut.

Trial assembley

Note the inner support stub.

That's as far as I can go with the outriggers until the chassis is ready to have them welded on.

Chassis Final Strip

Time to completely strip the chassis of all fittings, remove all remaining rusty bits and get it blasted back to bare metal.

Chassis completely stripped of all fittings.

The axle mounting tube triangulation struts are an open C section and form a rust trap at there rear edge. Here it has been cut off (note the remaining stub on the mounting tube, this will be cut off flush).

If the end of the strut is corroded then the main chassis rail where it joins will also be corroded.

Cleaned up.

The left hand side was similarly corroded

No visible hole this side but you can see the build up of exfoliation in the rear of the pocket so the metal has thinned here and will require repair.

All remnants of the triangulation struts ground off.

Loaded onto a borrowed trailer and off to a local media-blasters to be cleaned back to bare metal.

and back home again.

What a difference! It is so much easier to see the detail of the chassis now and what needs doing. It has suddenly become a much nicer thing to work on. It was given alight coat of rich primer to give it some temporary protection.

Chassis Repairs

With the chassis stripped back to bare metal the repairs can begin.

First up was the two thinned sections at the very rear. This chassis is actually in very good condition back here with just two repairs to be let in.

The repairs were welded from both sides before being ground flat both sides.

Underside view post a dusting of paint.

For the next bit the chassis was mounted on its side for both access and because gravity effects welding too.

The holes in the main rails from the axle mounting tube struts is tackled next.

Being careful not to go deeper than the outer skin with the cutting disc so as not to damage the internal skin.

Cleaned up.

Cardboard template.

Transferred to metal.

The internal face is sprayed with weld through primer.

As is the internal void of the repair area.

It is then welded in place.

Trimmed, end welded and then all welds ground flush.

A quick blow over with zinc rich primer.

Media blasting revealed just how thin the left side was, this was repaired in the same manner.

Front Outriggers Fitment

Final fitment of the previously fabricated front outriggers

Front outriggers were drilled to allow plug-welding to the inner support stubs.

You can just make out in this photo that the inner support stub has had a large hole drilled and flared into it. This is to make it go faster!

Slid into position. Prior to this the inner surface of the out-rigger and the mating surfaces of the support stub were cleaned back and then given a coat of weld-through primer.

Once happy with its alignment it was G-clamped in place (holds it tight against any springiness against the inner support stub).

Note the heavy duty spring clip holding it against the datum post.

Plug welding.

Both sides.

Welds ground smooth.

Note the top edge has been seam welded to the chassis and ground smooth.

The left hand side being prepared for welding.

Plug welded and ground smooth.

Both outriggers were then seam welded to the main chassis rails and the whole area given a blow over in zinc rich primer.

Outer Rails Trim to Length

Front end overhang to be removed.

The alignment jig showing its worth.

Forward end cut back to front outrigger. Note the alignment/datum jig has now been removed, it has done its job.

The rear excess also needs trimming but allowances must be made for the original B-post body hoop mounting.

Ignore the big rectangle hole in the top face, that's coming up!
The holes are only in the outer face of each rail so from now on the rails are 'handed'. The excess length is cut away around the bolt hole. The inner face is cut square but leaving enough overhang to provide some strength. The holes are along the center line of the rails height and equidistant from the center line of the chassis tube hole.

They are 3.75" apart...

and 14mm dia.

Seatbelt Pedestals / Roll Cage Main Hoop Mounts Prep

I am incorporating provisions to mount a six-point roll cage in the future. The existing roll cages all use the seat belt mounting pedestals as the basis for the main hoop mounts, but they need beefing up. This is how I approached it.

The area in question.

Cardboard pattern of the new pedestal platform. This will be let into the top of the outer rail so that it sits flush as per the original. The extension forwards along the top of the rail is to increase strength along the join.

Section or the top face of the rail marked...

and cut out. The new platform top plate is being cut from 3mm thick sheet as per current MSA requirements (assuming I have interpreted them correctly) so the cut-out needs to be 3mm deep.

Refitted in place.

The two outer cage mounting bolts are likely to pass through the area of the outer rail so an access hole is cut into the side to allow access to the nuts.

Cardboard pattern transferred to 3mm thick steel sheet.

Trial fit.

The other rail was then cut to match so as to ensure I has a mirrored pair.

A support stub is required for the forward edge of the plate. It has been designed to slot inside the cut-out and so spread the load into the entire box section as apposed to just the one edge.

This was also cut from 3mm sheet. The hole was added to allow airflow through the chassis rails and for the galvanizing process.

Trial fit before seam welding in place.

Repeat for the other side.

That's as far as these can be progressed until the outer rails are welded to the chassis.

Center Outriggers Fitment

Final fitment of the lowered center outriggers.

More go-faster flared lightening holes in the center outrigger support stubs.

Note the flanges point downwards so as to avoid potential dirt/rust traps.

New outrigger slid into position to recheck fit. Not shown in these photos, the outer rails was temporarily placed in position to help line it up.

Holes drilled ready for plug welding to the inner support stub.

Plug welded in place. Again the mating surfaces of the support stub and the outrigger were cleaned and sprayed with weld-through primer.

Both new center outriggers fitted, seam welded to the main chassis rails and given a blow over with zinc rich primer.

Front Roll Cage Mounts

The location for the front roll cage mounting platform took a bit more figuring out as there is no natural intersection on the chassis for the front tubes to join. The front cross members are buried at the ends of the foot wells, way too far forward. A new structure would have to be incorporated somewhere along the length of the outer rail.

First job is to establish the most suitable/likely location for the front mounts. With not having a premade Scimitar roll cage to hand I made a roll cage tube simulator from a piece of domestic drain pipe. The roll cage tube needs to be 45mm diameter so the pipe has been sleeved to meet this.

Positioning.

The fresh air ducting forms the primary dashboard mounting point. As the steering column is mounted directly to the dashboard on this vehicle it is rather important that not too much strength is lost.

This location seems to work best. Some of the ducting will need cutting away and reforming but it is far forward enough to not encroach on the dashboard mounting.

Conveniently, the bottom end of the tube lines up with a change in floor profile so I have a visual reference without having to get my felt tip pens out.

Not shown as I couldn't hold a camera at the same time, I held the outrigger up in position under the bodyshell and marked off this new position.

As with the main hoop mount, I will be laying in a 3mm plate mounting platform. I have made the platform wide enough to allow for a 10mm margin of error both front and rear and as before, I have extended the cut out beyond the final platform dimensions to create a stronger join.

As before, the outer cage mounting bolts will likely be in the area of the top of the rail so an access hole has been included.

The platform supports follow the same design as those for the main hoop. There final length hasn't been established yet, they will be trimmed one fitted. Two are required on each platform as there is no other surrounding structure to attach them to.

Outer Rails Final Fitment

Big visual progress, a mini-milestone.

Before the new outer rails are finally fitted I carried out an alteration to the rear suspension trailing arm mounting brackets. This had to be done prior to fitting the side rails as once fitted they would prevent the required access.
For details, click HERE

A mini milestone but not a lot to say really. They were offered into position and any required final trimming of the outriggers carried out to ensure a good 'square' fit.

They were then seam welded (in stages to prevent excessive heat build up) to the rear tube, centre and front outriggers.

Once done they were given a blow over with zinc rich primer.

Front Roll Cage Mounts Completion

As the front roll cage mounts are in the middle of a free section of the outer rails I decided to add an additional outrigger here to counter any twisting forces exerted on the rails by the off-set nature of the roll cage mounting (should I ever barrel roll it). Yes I know this is adding yet more weight but not a huge amount in the grans scheme of things compared to the difference it could make in the chances of my head getting squished.

A surplus piece of 60mm x 40mm x 2mm box section was suitable marked out...

...and cut...

...to create the bassis for the new additional outriggers.

Final cut to shape.

A straight edge was put across the chassis at the centers of the roll cage mounts and the chassis marked so as to ensure alignment.

New outrigger in position.

Welded.

With the outriggers fitted attention turned to trimming the support brackets.

The distance between the inner faces of the sills was measured.

As was the expected required extensions of the platform to take the cages feet.

With a bit of maths magic (still to be proven at this point), the distance between the two platforms was calculated and the excess trimmed off the supports accordingly.

A straight edge was placed across the chassis at the location of the mounting platforms to ensure they are mounted in the same plane to each other.

New top plates were cut from 3mm sheet and seam welded in place.

Both side fitted.

Additional brackets were cut from 3mm sheet to tie the platform and the supports to the new outrigger.

Here you can see the access provided to the roll cage mounting bolt nuts.

Seatbelt Pedestals / Roll Cage Main Hoop Mounts Completion

The seat belt pedestals / roll cage main hoop mounts can now be completed.

A straight edge was placed across the chassis at the location of the Pedestals to ensure they are mounted in the same plane to each other.

The plates were then given a final trim and ensuring they were square to the straight edge, they were welded in place.

The plates are seam welded at all contact points.

Finished with a quick blow-over of zinc-rich primer.

Triangulation pieces are cut from 3mm sheet.

so tie the plates to the suspension mounting brackets.

Fitted.

Here you can see the access cut-out for the outboard roll cage mounting bolt nuts.

Completed.

Seat Rail Supports

The seats were originally fitted directly to the fiberglass floor of the body shell. There were steel load spreaders bonded into the fiberglass but these had rusted away and considering the cars possible motorsport pretensions I would much rather the new seats be attached to something more substantial, such as the chassis. So I added some seat rail supports. These are simply cut from 30mm x 10mm x 1.5mm thick box section steel. These were positioned to suite the universal seat runners I had purchased.

In the Lowered Floor section of this site, before I lifted the body, I fitted a false wooden floor supported by bottle jacks. I marked out the position of the original center outrigger on this false floor to act as a datum.

I then positioned the drivers seat where it best suited my size in relation to the pedals and the steering wheel.

I had stuck a strip of masking tape along the outer seat runner and marked on this the location of the rear edge of the center outrigger.

With the universal seat runners set to the mid position the rear mounting hole is 185mm back from this datum. So the chassis outer rail was marked 185mm back from the new center outrigger.

Using a straight edge and checking for squareness against any datum I could find (rear chassis uprights and mk1 eyeball) I transferred this mark across the chassis to the main rails...

...and opposite outer rail.

The height of these new supports is dictated by the center outrigger.

The height was checked at both ends...

... to ensure it is level and the figure recorded.

there is a doubler at this location which raises the datum bar.

So to account for this...

... the distance from it to the outer rail was measured.

The datum bar was then moved to the location of the new supports...

... and the distance measured, the difference being removed from the recorded measurement to the top surface of the center outrigger.

The chassis was marked accordingly and the trimmed box section held in place with magnets.

Once happy it was welded in place, being sure that it was level fore and aft.

Both r4ear seat supports welded in place.

The datum edge was then moved 32mm forward to match the distance between the mounting holes on the seat runners and the chassis marked to give a starting point.

The front support was cut and trimmed from the box section and positioned so that it was the correct distance forward from the rear support to suite the mounting holes of the universal seat rails.

This also ensures that the front and rear supports are parallel to each other.

Its height was set the same way as the rear but was fine tuned with a straight edge as shown.

Once happy it was welded in position.

Then blown over with zinc rich primer.

Universal Seat Rails

With seat fitted.

The original datum markings.

Underside view.

Rear Roll Cage Mounts

Text

On the majority of the cages I have seen the rear bars mount to these outriggers. As standard these don't look to be strong enough so as they are corroded and need repairing/replacing anyway I am going to make stronger versions from 3mm plate.

I am also making them deeper to improve triangulation to the main chassis rails.

The front piece will follow the angle of the main rail so that I can create a mechanically stronger join and so that the outrigger better follows the contour of the bodyshell.

Prior to cutting the old outriggers off I need to establish a datum.

I marked off a few key positions but to be honest these weren't required. Having that straight edge in the right place is what counts.

Old outrigger removed and surface thoroughly cleaned back.

The new outriggers are being notched into the main rails to create as strong a join as possible.

Line up with the datum and mark out where it needs to be laid in.

Cut marks.

Careful cutting with a nice thin disc.

Cleaned and after trimming until the fit is good, sprayed internally with weld-through primer.

Reverse side of the outrigger piece also sprayed with weld-through primer where it will be enclosed in the chassis rail.

Tack weld and check with the datum bar.

Seam welded front...

... and rear (as shown by the heat marking).

Both front sections fitted and blown over with zinc rich primer.

The top plate is to be fitted in a similar manner noting that this piece is slightly larger to allow for the width of the outrigger it is replacing for the body shell mounting bolts.

Notch cut out.

Chassis rail marked...

... and cut to receive top plate.

Trimmed and adjusted for fit.

Seam welded in place. The internal areas were treated with weld-through primer prior to final assembly.

Getting a good seam weld required the chassis to be repositioned in a variety of angles (gravity acts on the molten weld whilst it is forming).

Welding complete.

Fully seam welded on all joints.

Matches chassis rail profile.

Both sides done and blown over with zinc ricj primer.

Remaining Chassis Repairs Completion

There are still a few general repairs to be completed on the chassis.

Rear Axle Mounting Tube Triangulation

The rear of these is a classic rust spot at it forms a rust trap that not only eats the rear of this part but also eats a hole into the side of the main chassis rails where these are attached.
The originals were a C section, in order to reduce the rust trap effect I have decided to use complete box section.

I have used 2mm thick 50mm x 40mm box section as that was the closest match I could get to the original piece.

Card board and guess work was used to get the basic shape which was then transferred to the steel.

The chassis rail end is a simple camfer cut.

The axle mounting tube is a little more involved, I used the hole saw I used previously when making the new outer rails to cut the curved shapes before I cut the box section to length.

Trimmed as required to get a good fit.

Seam wlded in place.

Welding the inner face was a bit of a challenge!

Both sides complete.

Rear Right Outrigger

The rearmost right hand outrigger had a hole in the top with the surrounding area significantly thinned so the area was cut out and a new piece of metal let in.

Holed and thinned section cut out.

Repair metal cut to shape and edges beveled.

Welded and ground smooth.

Zinc rich primer.

Pipe & Loom Guard

There is a small plate welded to the inner face of the left hand main chassis rail at the pinch-point. This acts as a guard to keep the fuel pipes and main wiring loom clear of the spinning prop-shaft. It was a bit bent so I decided to replace it, adding another to the opposite side for the brake pipes, just incase.

Dog-eared original.

Slimmer replacements fitted to both sides.

Front Suspension Tower Top Plates

The top plates of the front suspension towers have got a bit thin in places so were replaced.

The plates measure just shy of 4.5" x 3.5"

The chassis was levelled left to right with a spirit level (not the scissor jack) to provide a datum.

The two top plates were then cut off.

The cut faces were trimmed to ensure that they were true to each other, hence the leveling of the chassis and the use of a spirit level.

As the body shell requires repair where it sits in these plates I have removed a little extra material, effectively lowering the height by a couple of mm, to allow for the extra thickness that the repair to the bodyshell will create. Note the internal bracing clearly visible in this view.

Replacement blank top plate, in this case 3mm steel as that is what I had available.

Trimmed to match the shape of the cut suspension tower.

The plates were positioned and the spirit level put across them. Any further trimming to get them sitting true was then carried out.

Enclosed faces painted with weld-through primer.

A heavy block of wood was used to hold the plates in position and once happy, they were tack welded in place.

Tack welded. Note that the plates are positioned slightly outboard exposing the inboard cut edge. This was so that the weld doesn't obstruct the mounting face of the bolt-on cross-brace.

Fully seam welded. Some final grinding/smoothing of this weld line may be required to clear the aforementioned cross-brace mounting plate.

Finished with a coat of red-oxide primer (I ran out of the zinc-rich primer).

That concludes the chassis repairs.

Mobirise

The contents of this website are purely a reflection of my own experiences and knowledge gained whilst working on my various projects. Anything you do based on what you have read here is done so entirely at your own risk.
Personally I wouldn't trust someone like me with a lawn mower! You have been warned! Flapper-bat!

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