Lotus Elan

Barn find chassis identification

PostPost by: Andiken » Sat Oct 14, 2017 8:53 am

Morning all


The barn find is revealing its secrets slowly, it has a galvanised chassis and galvanised sill side members, I guess that's a good start! Can anyone answer a couple of questions please?
Firstly, the vacuum chamber is broadly square in cross section with the top trailing edge chamfered at about 45 degrees, does this indicate a Lotus or Spyder chassis or is this no indication at all? The chassis looks to be in excellent condition from what I have been able to see so far.
Secondly, the machine screws that secure the lower edge of the fibreglass to the lower edge of the sill side members; should they be slotted pan head machine screws with nylock nuts on the inside?
Lastly, are these machine screws 1/4" UNF, they look it?

Thanks, Andy
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PostPost by: pharriso » Sat Oct 14, 2017 9:42 am

Andiken wrote:Morning all


The barn find is revealing its secrets slowly, it has a galvanised chassis and galvanised sill side members, I guess that's a good start! Can anyone answer a couple of questions please?
Firstly, the vacuum chamber is broadly square in cross section with the top trailing edge chamfered at about 45 degrees, does this indicate a Lotus or Spyder chassis or is this no indication at all? The chassis looks to be in excellent condition from what I have been able to see so far.

Thanks, Andy


That's definitely a Lotus chassis, not sure if original chassis were ever galvanized, whereas replacement Lotus Chassis were, so that could indicate a replacement Lotus chassis which is great!
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PostPost by: elanman999 » Sat Oct 14, 2017 9:45 am

Andy,
If the chassis is galvanised with a square (ish) Vac chamber then it's a Lotus replacement chassis.
Cheers
John
Edit, Pharri you beat me to it. Galv chassis came in in the early to mid 80's.
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PostPost by: alan.barker » Sat Oct 14, 2017 9:57 am

Also replacement chassis are engraved LR XXXXX exhaust side rail :wink:
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PostPost by: stugilmour » Sat Oct 14, 2017 2:40 pm

Andy, I believe the screws you are referencing are hex head, 3/8? dia UNC x 1? length in stock form. They typically screw in to threaded metal bobbins inbedded in the fibreglass. Perhaps the bobbins were stripped and therefore replaced with a 1/4? nut and bolt combo?

To determine the hardware sizes on most of the car, Lotus used a standard part number system. You can see the secret decoder ring explanation at the RD Enterprises on line parts catalog.

http://rdent.com/manuals/index.html

Go to the introduction section of the parts manual and it shows the codes. e.g. the part number you are wondering about is XUCS0616 which is
X, hex head
UC, UNC
S, screw
06 = 6/16? dia
16 = 16/16? length

The bobbins are available, and pictured on the RD site. Click on Plus 2 parts and they are about the third item down. I am sure there are other suppliers with them over your side of the pond.

http://rdent.com

HTH. All the best with the archeological examination! :D

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PostPost by: Sea Ranch » Sat Oct 14, 2017 4:38 pm

Andy, my esteemed friend Stu may be talking about something different.

At the lower edge of the car (from the side) (the strip of black paint along the bottom of the sill/rocker) there are a row of slot pan head screws that go through the lower fiberglass flange, through the lower flange of the sill member, through the inner fiberglass, and into the cabin, along the bottom. They should have a washer and nyloc nut on the inside. Believe they are 1/4" as standard. I prefer stainless. I personally used a larger head (truss head) so as to better clamp the outer fiberglass flange after 40 years of battering.

Hope that helps :mrgreen:

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PostPost by: stugilmour » Sat Oct 14, 2017 5:32 pm

Good eye Randy. My bad.

Andy, I read your post too quickly, and was referring to the body attachment on the frame tunnel lower flange plate.

I took a peak at the RD parts list for the rocker re-enforcement rails that you are asking about. Note they seem to have the part numbers different from my parts book. That said, it looks like RD calls up a screw and nyloc. Maybe a running change? RD seems to call up the configuration you and Randy have, but perhaps in a different size? The numbers don?t seem to decode right, so maybe a typo or two going on?

Qty 22 - FUFS1012 UNF screw 5/8? dia x 3/4? length Not sure what head type F is?
Qty 22 - YUFN100E Nyloc UNF nut 5/8? dia full? (If the E is really F?)
Qty 44 - A03W0605 Plain Washer 3/8? ID 5/16? OD which doesn?t make much sense?

I didn't do the rails on my car, the previous owner had replaced them. As Randy did replace his rails, I would defer to him.

However, I understood (from the way my car is done and my parts book) the rails are drilled and tapped as required to accept quantity 36 of part number XUFS0412 (no nut). This screw would decode as
X, hex head
UF, UNF
S, screw
04 = 1/4? dia
12 = 3/4? length

Interesting. Randy?s car is later than mine, so if there was a change his is the ?improved? version. I must say the hex heads on my car do look a bit bush league, but coated with black undercoat they are not that noticeable. Given that mine are 1/4?, I think you are good. Maybe someone with a newer parts book can check / confirm the RD part numbers?

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PostPost by: Andiken » Sat Oct 14, 2017 6:01 pm

Thanks so much for the input all.

Today I have cut off the slotted heads and punched out the bolts. Having removed the forward closing panel and pulled the sill member out I can confirm that both sill member and closing panel are galvanized. Result!

The screws are as Randy says so I'll be ordering some suitable replacements and fitting them before moving on to the other side. The inner spreader plates have now been stripped and prepped. I'm going to zinc plated them, passivate them, etch prime and paint them before putting them back into the car.

It's such a relief to find that the sill members have been replaced and not turned to dust!

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