Lotus Elan

Shims between Body and Chassis

PostPost by: mariodschy » Tue Nov 25, 2014 12:57 pm

Hello,

yesterday i removed the body form the chassis and was very supprised to see that they were only shims on the left siede (2 to 4 on each fixing point), on the right side only in front there were 2 shims everwhere else there were no shims.

I am sure that it was the first time ever that the body was removed, did somebody else have the same expirence.
I thougt that normaly should be the same number of shims on each side.

Mario
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- 1972 Lotus Elan Sprint LHD/DHC
- 1962 Austin Healey Sprite MK II - Sold 09.05.2016

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PostPost by: TroonSprint » Tue Nov 25, 2014 1:59 pm

I am in the middle of rebuilding my Sprint FHC and my experience is this. The body sits down on the chassis spine and you can jump and down in it to bed it down nicely. When you get underneath you find that not all the pads along the length of the spine actually touch the body. Some do and some don't, and if you think about it, it isn't surprising. The bodyshells are basically hand made so there are bound to be individual variations.

I was able to screw the big bolts on top of the spine (by the gear lever) down firmly, but needed thin shims on some of the lower mountings. None were thicker than about 3/16 inch and I used pads of a plastic material. I wouldn't worry about it. I suspect it is quite usual.

Mike
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PostPost by: mariodschy » Fri Nov 28, 2014 9:27 am

Thank you for your answere, enclosed is a exact plan of the shims.
I think the different quantity is very high, i'll check if this is really proper befor i fit the body...
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- 1972 Lotus Elan Sprint LHD/DHC
- 1962 Austin Healey Sprite MK II - Sold 09.05.2016

Sorry for my bad survival English ;-)
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PostPost by: rgh0 » Fri Nov 28, 2014 9:39 am

While shims are not unusual they are usually of similar thickness on each side for each pair of bolts. Unusual to have a significant consistent need for shims down one side only.

The chassis appears to be a galvanised one -- is this the case? These are known to have problems with distortion when being galvanised - maybe this is the cause?

cheers
Rohan
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PostPost by: elansprint71 » Fri Nov 28, 2014 10:31 am

I found that the body on my 72 car could be moved side to side about 5/8" or 15mm when I took the bolts out. There were some shims down the front end, different thicknesses on each side. I think the critical points were the clearance between tyre and wheel-arch at the rear and clearance between cam-cover and bonnet up front and packing was used to make the thing right as quickly as possible during production.
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PostPost by: Grizzly » Fri Nov 28, 2014 11:58 am

When i placed the body on the chassis and placed vertical bolts in none of the Horizontal bolts where even close, so at that point i though i'd distorted the chassis when it was powder coated, but i was flicking through some of the diagrams the Previous owner had made when he stripped the car and there was a diagram of the shims. It was shocking how many it required but when they where in place the Horizontal bolts went in with no problem what so ever.

The odd thing was that with no shims in the body looked more straight on the chassis than with the shims in but the doors would catch on the strikers with no shims so not how it came apart. With mine i had three shims down the Passenger side and 1 down the Drivers side, it did cross my mind it was to help set the corner weights of the car with the driver sat in it but your expect the drivers side to be lifted more??

O well the trials and tribulations of GRP body shells.
Chris
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PostPost by: alan.barker » Fri Nov 28, 2014 1:01 pm

imho the shims are to let the body settle down without stress+ camcover not to touch bonnet (have cracks)+ not deform or put pressure on the steering rack pads (have bump steer problems).
When i fit a body on the chassis i like to see a gap between the steering rack pads , so i can shim and not deform them
Alan
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PostPost by: Grizzly » Fri Nov 28, 2014 1:42 pm

The Steering Shims are some thing else, that is to set up the Bumpsteer.

IMHO the Body-Chassis shims are there to adjust for any shrinkage or movement in the GRP structure, i'm under the impression each chassis is drilled for its corresponding shell because the Bobins where fitted more or less in the same position. So if you get a fresh GPR shell it will deform slightly until its fully cured, therefore if its not bolted to the Chassis during this time it will move out of wack, hence the Kits where shimmed and allot if not all the factory cars weren't.
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PostPost by: jimj » Fri Nov 28, 2014 2:15 pm

Chris, the "kits" were supplied with the body attached to the chassis, in fact there was nothing to attach to the chassis at all. There was just the suspension at each corner to bolt in, connect up the driveshafts, and fit the engine and gearbox then radiator. That`s all.
Jim
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PostPost by: Grizzly » Fri Nov 28, 2014 3:21 pm

Thats odd, it seems your right lotus-elan-f19/elan-kit-build-article-t25635.html

But i have pictures taken of my car when it arrived and being assembled, the body was off the chassis but the chassis was rolling with the engine and box out. (one of the advantages of one owner cars and the PO being available to talk too)

Ok there goes my theory, i thought all the kits where like mine. That said mine seems to be a bit of an odd one as it's a very early S4-Sprint and even had striped decals at the back, so i have no idea what was going on there.

The shims where probably an attempt to get the bolt hole in the middle of the Chassis double thickness plate which would have been fixed via Jig in the correct place so any deviation would have been in the GRP hence the shell being tweaked to the chassis and not vise versa
Last edited by Grizzly on Fri Nov 28, 2014 3:31 pm, edited 1 time in total.
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PostPost by: alan.barker » Fri Nov 28, 2014 3:31 pm

chris i do not mean the shims for the rack height at all.
I am saying if when the body is fitted it is exerting pressure on the pads infront of the rack where the body is attached it will deform them or distort them. If that happens your rack height goes out the window
Alan
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PostPost by: Grizzly » Fri Nov 28, 2014 3:40 pm

Really? unfortunately i don't have a good picture but my rack is fixed to a big box section with two legs that stick out the body floats over. My rack is so solidly mounted to the Chassis i was using it to pick the Chassis up to put it on stands :)

Image

When the body goes on there is a 5-10mm gap between the body and the chassis at the two mounts near the rack (doesn't make contact even with all the body shims out) mine then has too tubes the go between the body and chassis and two odd spacers on the top. I would fear that if there was pressure put on the two rack mounts you would crack the body before bending the rack out of position.


Is yours not like that?


BTW, Note my Horizontal upright Body holes are bang on center of the double thickness plate.
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PostPost by: mariodschy » Tue Dec 02, 2014 11:52 am

rgh0 wrote:While shims are not unusual they are usually of similar thickness on each side for each pair of bolts. Unusual to have a significant consistent need for shims down one side only.

The chassis appears to be a galvanised one -- is this the case? These are known to have problems with distortion when being galvanised - maybe this is the cause?

cheers
Rohan


It is the original chassis, it don't looks like galvanised.
Attachments
IMG_5808.JPG and
- 1972 Lotus Elan Sprint LHD/DHC
- 1962 Austin Healey Sprite MK II - Sold 09.05.2016

Sorry for my bad survival English ;-)
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PostPost by: Grizzly » Tue Dec 02, 2014 12:06 pm

Does the Chassis number match the build records? Its getting quite Unusual now to see the original chassis under an Elan, most have been changed due to Corrosion or accident damage.

Nice to have a Numbers Matching car.
Chris
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PostPost by: Hawksfield » Tue Dec 02, 2014 12:33 pm

Hi All
There was no shims at all on my chassis to body, the chassis was original red leaded and black bitumastic paint with correct chassis number. carried out in 1986.

Was there any galvanised chassis fitted originally by Lotus to Elans/+2s ?
John

+2s130 1971
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