Drilling/tapping new Elan chassis without lifting the body

[Crash test dummy]

Hi everyone.
So I just fitted a new old stock chassis to my Elan Dr project today.
I did a fair bit of reading about the process beforehand - a lot of it on this forum - and the general consensus I got was to fit the body, mark the holes, lift the body to drill and tap, then refit it.

Given the moderate challenge of lifting and fitting the body into the chassis the first time, I wondered if I could drill and tap all the holes in situ without re lifting it.

To that end I bought a cheap 90 degree drill adaptor from eBay - see attached.
I made up three different plugs on my lathe with 3mm centre holes for the different bobbins, and was able to drill them all in place. Even the gearbox tunnel was manageable with the heater unit still in place, as was the offside front turret - just!

To drill out from my pilot I shortened a 5mm and 8.5mm drill bit and was able to drill the holes and then tap them without any issues.

I drilled through the rest of the bobbins (the threaded ones) from above using my guide plug, then drilled out the holes from below being careful not to damage the bobbin. The awkward one was the one just inside of the front of the footwells which is blind so I couldn't drill from above, but using a bit of wire with a 90 degree bend on it as a feeler I could work out the position of the hole fairly accurately and then after drilling out to 8mm used a small rotary file to get the hole properly centred on the bobbin.

Then fitted all the spacing washers by pushing in from the side, using a jack and wooden board to lift slightly if needed in each area.

All in all, it took me (with my dad helping) the best part of a morning to get the body fully bolted in.

I'm not sure if that is quicker or slower than lifting the body back up and refitting after, but I thought people might be interested to know that it is possible as I hadn't seen anyone suggest it before!
I hope this helps someone in the future.

[Billelan]

I used the same procedure when fitting a new chassis to my S4 some 35 years ago! I don’t remember any of the footwell bobbins being blind though.

[Crash test dummy]

I was sure I couldn't be the first person to try it, but hopefully this post can help someone else in the future!
Perhaps I'm wrong about the blind bobbin, the one at the very front of the footwells? I had a prod and couldn't find it under the carpet but I didn't remove the carpet from the car so I might just have missed it.

[Foxie]

Related to this topic:

I am planning to fit my old original Lotus chassis ( now replaced with a Spyder chassis ) to another basket case +2 whose chassis is pure rust.

I think due to random bobbin misalignments I will have to plate over or weld up the drillings in my old chassis.

Has anybody done this, and how did they manage it ?

[Crash test dummy]

Funnily enough, the new chassis I fitted had actually been previously fitted but not driven anywhere before being removed for a spider chassis. They'd welded the holes back up when they removed it and then ground it flat. Plates won't work in most areas as there isn't room for anything increasing the profile of the chassis.

[Foxie]

<Snip> Plates won't work in most areas as there isn't room for anything increasing the profile of the chassis.

I'm not sure I would agree. It seems to me there would be no problem in welding and drilling plates on the 10 vertical attachment points underneath the existing flanges.

The other 6 I would fill with weld, grind, and redrill.

[Crash test dummy]

Yes I suppose you are right, as long as the plates were on the underside of the flange for those points it would be fine. It's probably about the same amount of work as welding the holes up though...

[alan.barker]

For the 6 threaded holes i suggest you make threaded Plugs. Then just a little spot weld to lock in position. Not too much welding as it makes it difficult to Drill and Tap the new holes to suit Body holes.
Alan

[Donels]

Why weld anything in. A suitably large washer on the underside with shims to align the body on the top side should clamp things pretty tight. The torque figure for the bolts into bobbins is only 20 lbs ft I think.

For the vertical holes Brian Buckland does warn not to use a welded in bolt to close the holes as it makes retapping very difficult.

When realigning mine recently by slightly opening the rear bobbin holes the bolts could be fitted. The fronts were miles out and the bobbins had to be cut out and reglassed.

[alan.barker]

+1 you could fix the threaded Plug in place with a high grade Loctite
Alzn