Author Topic: Body off build tip  (Read 959 times)

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Offline BDA

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Body off build tip
« on: Saturday,June 01, 2019, 12:01:35 PM »
I think it's common to assemble the front suspension on the frame before lowering the body. That's what I did, at least. I also red loktite'ed the lower pivot in the frame. I considered drilling a hole and tapping it for a set screw for tightening the nuts for the A-arms, but didn't. I'm taking the lower A-arms off to measure them. I assumed all my A-arms were straight because I knew their history and they didn't look bent in the least. One day in a paranoid frame of mind, I had checked the caster on the driver's side to make sure I had assembled everything correctly - I had - so I didn't pay attention to the passenger side till much later. It turns out the caster on the passenger side is off. Now, I'm taking the lower A-arms off the passenger side (I have tubular adjustable A-arms at the top and there is now way they are bent) and I find that I'll have to do some grinding on the body or the pivot or both to take the rear A-arm off!

I have a few suggestions for those of you who are doing body off restorations. They really apply when you are using new lower pivots such as if you have a new frame:
1. Assemble the suspension after the body is lowered to the frame so you can adjust the position of the pivot before you lock it down.
2. Consider drilling and tapping a hole in the tube for the lower pivot for a set screw. This should be accompanied with grinding a flat in the pivot that is an inch or so long. This will allow you to adjust the final position of the pivot (of course, if you do this, it can be done before you lower the body!). If you take this route, anti-seize or grease on the pivot would keep it from getting rusted into the frame. At some point, you may want to take it out.
2a. Another possible option is to weld a nut on one end of the pivot and then install the pivot from the front. I think this is best done after the body is mated to the frame to ensure proper clearances.
3. Probably most importantly, if you use stock A-arms (I recommend this since they are designed to absorb a lot of the energy in an accident helping to save your frame), measure them first before assembling everything. Don't trust the way they look. Before I started taking it apart, I put a straight edge on three sides of both arms and the only thing I could find was a very slight bowing on the vertical side - no deformations on the horizontal sides.

I hope this helps somebody.

edit: added option 2a.
« Last Edit: Saturday,June 01, 2019, 01:32:59 PM by BDA »

Offline Certified Lotus

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Re: Body off build tip
« Reply #1 on: Sunday,June 02, 2019, 04:07:23 AM »
Thanks BDA, great insights. Can you show us on a drawing the areas your talking about.
« Last Edit: Sunday,June 02, 2019, 04:13:40 AM by Certified Lotus »

Offline BDA

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Re: Body off build tip
« Reply #2 on: Sunday,June 02, 2019, 05:58:31 AM »
We want to be sure to be abe to ge #21 off. #23 is the pivot I'm talking about. Lotus calls it the "lower fulcrum." If that fulcrum is too far to the rear, you won't be able to get the rear A-arm off because the A-arm will still be on the fulcrum when it hits the body. That's why I think it's a good idea to be able to move the fulcrum when you need to disassemble the lower A-arm. if you use two nuts, I recommend grinding a flat on the fulcrum and drilling and tapping the tube the fulcrum goes into for a set screw so the fulcrum won't turn when you tighten the nuts. It looks like there is enough room in front of the lower suspension that you could make the fulcrum into a bolt by welding a nut (I used jet nuts - Pegasus is the only place I know that has 1/2 - 20 jet nuts) and introducing the fulcrum from the front. I've obviously not tried it so note that I said "looks."

If you still have questions, I'll take a picture of my problem and if will become blindingly obvious!  :D
« Last Edit: Sunday,June 02, 2019, 06:09:56 AM by BDA »

Offline Chuck Nukem

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Re: Body off build tip
« Reply #3 on: Tuesday,November 26, 2019, 05:18:21 PM »
Sorry to revive an old thread, but is that fulcrum supposed to be removable from the frame? I thought it was a solid shaft that was turned on both ends and welded in...Mine is obviously very stuck if that is the case.

Offline BDA

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Re: Body off build tip
« Reply #4 on: Tuesday,November 26, 2019, 05:42:43 PM »
I think when you get a new frame, like I did, the fulcrum pins come separately and you have to install them. My memory was that on the original frame for my car (from Lotus) it was solidly mounted which is why I came up with the idea of using red Loctite. When I had to take my lower A-arms off one side and the rear one wouldn't come off because between the fulcrum pin and the body, there wasn't enough room to take it off, I came up with the set screw idea. More recently, I have seen where some have double nutted one side of the fulcrum pin so you wouldn't have to lock it to the frame.

If yours is already locked in the frame and you're going to reuse that frame, just go with what you have. If not, you have to come up with a way of holding the pin steady when you tighten the nuts on the ends.

Offline Pfreen

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Re: Body off build tip
« Reply #5 on: Tuesday,November 26, 2019, 05:54:12 PM »
The pivot bolts On my tcs  are removable and were made of 1/2” rod threaded at both ends.  I replaced mine with grade 8 bolts, which are removed through holes in the body.

They were not welded in in my car.

Offline BDA

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Re: Body off build tip
« Reply #6 on: Tuesday,November 26, 2019, 06:49:00 PM »
So you took your original fulcrum pins out and replace them with bolts?! Interesting! Can you tell us more about how that works? How long were the bolts? What did you screw them into? Anything else that describes how that all fits together.

Offline Pfreen

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Re: Body off build tip
« Reply #7 on: Wednesday,November 27, 2019, 06:18:28 AM »
The top bolt is about 12" long and the bottom bolt is about 10" long.  The top bolt is removed through the hole in the body and the bottom bolt is removed toward the front of the car.  They are 1/2-20 bolts.  Nylock nuts torqued to the specified torque are used to clamp the assemblies together.  The bolts feed through the chassis, A-arms and shock (top) like the original threaded rod.  My original threaded rods were corroded so I replaced them.

Sometime I can accurately measure the bolt lengths if somebody needs the exact measurements.


Offline BDA

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Re: Body off build tip
« Reply #8 on: Wednesday,November 27, 2019, 07:34:18 AM »
I had a nut welded on my top pins to make bolts out of them. I wouldn't have thought to buy a long bolt like that for the bottom pin. Bolts that long are not common to see but you can get pretty much anything on the Internet!

Offline surfguitar58

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Re: Body off build tip
« Reply #9 on: Wednesday,November 27, 2019, 08:20:51 AM »
I had a nut welded on my top pins to make bolts out of them. I wouldn't have thought to buy a long bolt like that for the bottom pin. Bolts that long are not common to see but you can get pretty much anything on the Internet!

McMaster has 'em up to 13 inches, grade 8 yellow zinc chromate. https://www.mcmaster.com/91257A656
"A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away."
Antoine de Saint-Exupery

Offline BDA

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Re: Body off build tip
« Reply #10 on: Wednesday,November 27, 2019, 08:55:45 AM »
Surf, your link goes to a 3/8 bolt but your point is taken. McMaster-Carr is local in a lot of cities. The bolt that Pfreen used for his lower pin was listed at $11.47 (https://www.mcmaster.com/91257a505) which is not a bad price if you want to avoid the double threaded pin that is standard.