Caution re: removing rear cage

[Seymour Snerd]

SPF owners: if you have never removed and replaced your rear cage, be prepared to do some work to put it back on. Mine came off easily, but since it came off one bolt at a time I had no idea how much stress I was releasing (its stress, not mine).

This weekend it became time to refit it. I disovered that all five of the six 1/2" mounting holes that could be were significantly misaligned relative to the "hoop", in one case by more than 1/8".

Even worse, the bottom of the cage at the front is a length of square tubing with two 1/2 tubes welded through, which in turn accept a pair of bolts to thread into the lower hoop. These tubes were not at all perpendicular to the hoop, and thus grossly bind when just the two are tightened.

The moral is be prepared for some work with a rat-tail file or burr before you put the cage back on.

I don't want to think about how it was assembled in the first place.

 

[Randy V]

1/8" is not bad at all!

While I know nothing of the specifics of the SPF cage - It's not uncommon at all for this to happen with a bolt in cage.

Most bolt in cages have from 2 to 4 bolts at each point.

I typically start a bolt, then go to the opposite corner and pull the cage tube into alignment with a long philips screwdriver, and start the second bolt, then off to another corner and so on...

Here is the cage I built for my RCR..

 

[Seymour Snerd]

.... It's not uncommon at all for this to happen with a bolt in cage.

By "happen" do you mean as in an aging process, or do you mean during construction of the cage? (BTW I use the word cage here loosely; this is not a roll cage; it's the frame of the car to the rear of the bell housing).

IAE, I attempted the one-bolt at a time, leave-them-loose-until-the-end method familiar to any Harbor Freight customer. After an hour it was clear there was no way it was happening without hammer force and danger to the bolt threads and captive frame threads that secure the suspension lateral arms. This is not tabs mating to a plate: these are stacked assemblies with bolts feeding into threaded tubes that expect to be coaxial, and are subsequently to be accurately torqued. We don't want built-in stress in that context.

Also, it will be coming off again and again. I like my cars to be "service friendly," so those bolts are going to spin in until they bottom finger tight. Whether they like it or not.

 

[Ron Earp]

Also, it will be coming off again and again. I like my cars to be "service friendly," so those bolts are going to spin in until they bottom finger tight. Whether they like it or not.

Have you tried jacking the car are various points to see how the system moves? If the cage was installed in the car while the car was on a dolly of sorts, then heavy components were installed and the car put on its wheels, well, it might torque everything around enough to put stress on it and mis-align the holes. Jacking it up in various positions might re-align the cage. Just a thought.

 

[Randy V]

Sorry Alan, I thought you were talking about a roll-cage...

They welding process will cause the metal to pull and move - putting a fair amount of stress into itself and the chassis.

I'd try Ron's idea.. I don't think I would elongate or enlarge the holes unless you absolutely had to.

 

[Rich E.]

FYI, I've installed/ replaced a couple cages in various projects in the past. I've just gotten used to bringing a small bottle jack and a ratchet strap to make things easier...

The metal has a memory that has to be overcome. Especially if the mounting points were bolted down with the tubes only tacked in place then finished while off the car.

Rich.

 

[Seymour Snerd]

Whoa, did I post in the Yugo ghetto-student-owner forum by accident? :uneasy:

Regarding the caution against elongating: When I'm done elongating I'm going to weld a new piece over the existing one with a proper round hole, or simply cut off the ear and reweld with everything in situ. You know, like it should have been in the first place.

In a couple of the cases (the upper two ears) there is some flex and I could lever it if I wanted to. But like I said why would I want to? In the long run from a maintenance POV it's truly truly easier to fix it properly than eff with it every time I take it apart.

But in the case of the four holes along the bottom: they're all on the same 12" piece of square tubing and they simply don't line up with the hoop. It's one 12" rigid piece of steel who's holes don't line up with those in the neighbor 12" rigid piece of steel. Am I being clear?:furious:

Trust me guys: the piece is f**cked up and the factory hammered it together anyway. To put a finer point on it: I was explicitly warned early on by some well-known professionals that I would be elongating holes in cage in the process of doing this because that's what they had to do.

And to be even more blunt: None of you would have gotten it back together without a hammer and damaged fasteners. Jack..... all you want. If you feel better explaining that away as residual welding stress or force distribution changes from jacking or global warming, fine. But I am not comfortable with that level of mechanical integrity in a 2500 lb vehicle with a 550 ft-lb energy source and a top speed of near 200 mph. I want those lateral links staying right where I left them.

BTW I no longer want a ride in your cars. :laugh:

My original purpose was to warn other SPF owners not to casually take it off because it might not casually go back on, and I absolutely stand by that warning. Just trying to save you all from a disappointing Saturday.

 

[Ron Earp]

And to be even more blunt: None of you would have gotten it back together without a hammer and damaged fasteners. Jack..... all you want. If you feel better explaining that away as residual welding stress or force distribution changes from jacking or global warming, fine. But I am not comfortable with that level of mechanical integrity in a 2500 lb vehicle with a 550 ft-lb energy source and a top speed of near 200 mph. I want those lateral links staying right where I left them.

BTW I no longer want a ride in your cars. :laugh:

Sounds a bit more difficult than I originally thought. I simply suggested jacking thinking that maybe just one simple flex in one direction would have it all line up.

Yesterday when I installed a rear portion of my cage that I unbolted two weeks ago for service I did nothing other than insert the bolts and tighten the nuts. That is the way you want it. But, my cage was done locally with the components of the car installed and that might make a big difference. Could be these SPF rear sections were done as components during assembly and expected to go on any SPF production car.

 

[Seymour Snerd]

Could be these SPF rear sections were done as components during assembly and expected to go on any SPF production car.

In some kind of "worst of both worlds" way because if that were the intention it didn't work. Like the jigs are really sloppy, or there are no jigs.



Probably I should have included this picture in the first place. Here's the lower right side. I cut the heads off the 1/2" bolts and slotted them for use as locating pins. The one on the left is centered in its ~1" long tube and threaded another 1" into the hoop behind. The one on the right is also threaded ~1" into the hoop and would like to go through that ear but obviously can't. The camera is aligned with the one on the right, so the one on the left looks off-center in its tube, but it's not.

You could probably pull all this together by starting each bolt just a few threads in, possibly aided by a drift ahead of the bolt, without damaging threads. I tried it without a drift and never found a sequence of bolt starting that worked. But then there are 720 different sequences so maybe I gave up too early. :cry:

 

[Rick Muck- Mark IV]

Alan,
As an aside, what bellhousing are you using?

And I partially removed the rear structure form a Mk II I had here, but decided better as I really didn't need to take it off, I was just "fiddlin" with the chassis. There does seem to be a fair amount of "spring" on the installed frame.

 

[Ian Clark]

Hi Alan,

I see your predicament, besides being annoying the misalignment of the holes shouldn't be there in the first place. The question is if the way the chassis is supported is contributing to the problem. I suspect not as we're looking at the bottom of the rear hoop and the SPF chassis is plenty strong.

Be that as it may, I'd be grinding out the holes in the base plate of the rear cage so the part fits on easily. The holes would be opened up enough to sleeve the bolt holes so once you know the cage is back on the car, square both horizontally and vertically, the sleeves can get tig welded into the base plate.

Then the part is absolutely perfect for your car.

Just my 2c worth, hope this helps

Cheers

 

[Ron Earp]

So this isn't any part of a cage, right? This is just the "rear scuttle" that holds up the rear clip?

 

[Ian Clark]

Hi Ron,

Yep, the part in question is the rear body support subframe (scuttle) that bolts to the horseshoe collar. Bit of symantics, not a part of the "cage" as we'd relate to roll cage.

Cheers

Ian

 

[Ron Earp]

Hi Ron,

Yep, the part in question is the rear body support subframe (scuttle) that bolts to the horseshoe collar. Bit of symantics, not a part of the "cage" as we'd relate to roll cage.

Cheers

Ian

Ah ha! I got it now. Well, in that case I'd have no problem beating it into submission.

 

[Randy V]

Whoa, did I post in the Yugo ghetto-student-owner forum by accident? :uneasy:

Excuse me? A few of us answered your post to try and assist and you throw this in our faces?

I don't eff'ing think so....

 

[Seymour Snerd]

Alan,
As an aside, what bellhousing are you using?
.

Mark --

Quicktime.

AFAIK it and Kennedy are the only FE-ZF bell housings. Do you know of any others?

 

[Seymour Snerd]

Excuse me? A few of us answered your post to try and assist and you throw this in our faces?

I don't eff'ing think so....

I'm sorry, I was trying to be funny. I guess I hadn't established the context for the joke well enough.

 

[Seymour Snerd]

Hi Alan,

I'd be grinding out the holes in the base plate of the rear cage so the part fits on easily. The holes would be opened up enough to sleeve the bolt holes so once you know the cage is back on the car, square both horizontally and vertically, the sleeves can get tig welded into the base plate.

Bingo!

I've been trying to think of a clean way to do that. As it is those holes in the base plate are already sleeved with 1/2" ID tubing, and the magnitude of misalignment is around the tubing wall thickness so my quandary was how do I "relocate" them. Obviously a hole saw of size = tube OD would do it, if I could pilot the hole saw somehow (stuff the tube with 1/2" AL rod or carefully chosen/fabbed tubing).

Or just drill 'em out with size=OD drill and replace them. I guess that's the fastest.

Or... ???

I wasn't quite so worried about moving the other (link-end) holes because, after all, those ears are really just de-cantilevering the link mounting bolts; they're not establishing suspension geometry.

Comments?

 

[Seymour Snerd]

Re: Caution re: removing rear thingie

So this isn't any part of a cage, right? This is just the "rear scuttle" that holds up the rear clip?

Uh-Oh... vocabulary lesson for me. "Scuttle?" All I get in various dictionaries is:

scut·tle 1 (sk

t

l)
n. 1. A small opening or hatch with a movable lid in the deck or hull of a ship or in the roof, wall, or floor of a building.
2. The lid or hatch of such an opening.

I'm not arguing; I collect words like this. Is this by any chance a "Britishism?" (where's my OED? Oh that's right, I can't afford one...)

"Subframe" definitely, wish I'd called it that in the first place. Sorry about the "roll" cage confusion; that nearby interpretation didn't occur to me.

I got to cage because of 3 & 4 below.

cage (k

j)
n. 1. A structure for confining birds or animals, enclosed on at least one side by a grating of wires or bars that lets in air and light.
2. A barred room or fenced enclosure for confining prisoners.
3. An enclosing openwork structure: placed a protective cage over the sapling; a bank teller's cage.
4. A skeletal support, as for a building; a framework.
5. An elevator car.
6. a. Baseball A large wire screen placed behind home plate to stop balls in batting practice.
b. Sports A goal, as in hockey or soccer, made of a net attached to a frame.

Or, it's a cage because it keeps my transaxle from escaping?

 

[Mike Trusty]

Quote:
Whoa, did I post in the Yugo ghetto-student-owner forum by accident? :uneasy:

Interesting attitude toward those that were trying to help you.


Quote:
Am I being clear?:furious:

Obviously not. You were confusing some very intelligent people with the wrong terminology. Thanks for using the emotion icons so that we could tell what you were actually saying. Takes the possibility of "tongue in cheek" comments out of the question. Going to be interesting to see what kind of help you get in the future when you ask questions. But, I bet you will get the same curtious replies from these very helpful people.