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88 Cradle Swap thread |
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CFoss 
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Joined: 13 February 2007 Location: Canada Status: Offline Points: 580 |
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 Topic: 88 Cradle Swap threadPosted: 04 April 2008 at 9:08am |
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Anyone know where I can find a build thread for a 88 cradle swap. I looked on Pennocks but I keep coming up with engine swaps on 88 cars!
Thanks,
Chay |
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86 SE 3.4
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Dr.Fiero
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Joined: 12 February 2007 Location: Canada Status: Offline Points: 1726 |
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Posted: 04 April 2008 at 5:31pm |
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It's not that hard a swap depending on how 'crafty' you are.
Do you have a way to do some of your own steel fab work? If so, you can save a STACK and do a better job (IMHO) than going through Held for there (overpriced crappy) kit. |
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Roadfury
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Posted: 04 April 2008 at 7:45pm |
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why would you want to do the 88 swap? what advantages are there?
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Dr.Fiero
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Posted: 04 April 2008 at 8:32pm |
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MAJOR improvement in handling - the 88 is just totally superior.
I've got it in the back of my '87, and it's the best handling car I've driven (still has semi stock front). |
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CFoss
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Posted: 05 April 2008 at 12:38am |
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Yeah, I can weld (I have a 250 A AC ARC and a 150 MIG) and have access to basic tools like a grinder/metal cutting disk and a metal lathe, powder coater for finishing etc.
I saw on Pennocks (I think) that someone was talking about cutting a long thin triangle out of the early struts, then rewelding them and relocating the strut mounts on the top end, but the write up was lacking in dimensions/measurements. I found it hard to picture exactly what was needed to do the job to an appropriate level of accuracy. Perhaps you can shed some light on this? I wouldn't mind saving the 300+ bucks, plus, once I do it I can help others with the same if they want. Chay |
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86 SE 3.4
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CFoss
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Posted: 05 April 2008 at 12:42am |
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One more thing...I'm doing a total tear down so I may attempt the front 88 suspension as well. I have the front complete cali to cali, so I have most of what I need I think. I'll be documenting each step in the process for swap, with tons of pics etc.
Chay |
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86 SE 3.4
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Roadfury
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Posted: 05 April 2008 at 9:00pm |
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Why does it do that? Is it just more stiff? lighter? if its just more stiff could you brace the 84-87 cradles differently? |
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Dr.Fiero
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Posted: 06 April 2008 at 2:07pm |
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You'd have to see them side by side, and know how the geometry of suspension works to see/understand why it's so much better. I honestly wouldn't bother with the front though. In a lot of ways, I prefer my '87 over my '88 steering wise. It responds a lot quicker, and just feels better (though the '88 is much lighter steering wise). As for dimensions for the conversion - All you really need is a pair of cars sitting side by side, and you can get the measurements off 'em. Then, the way *I* was going to do the backend, was to use the way Held did it (with a modded strut, and coil over kit), but then intead of the way they make you cut out the top of your strut tower (yuck!), you'd make a plate that fits in the stock location (with studs sticking up as usual), then have a 2nd strut plate below it with the tipped in/fwd location of the 88 setup. Few (5?) tubes connecting the 2 plates together. A hole in the bottom plate to mount the strut to, and a larger hole in the top plate to let you get to the nut. The strut starting its travel position lower down is no big deal, as the thing barely moves at all with 350lb springs anyhow. That of course is just the basic concept in my head.
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CFoss
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Posted: 07 April 2008 at 9:01am |
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Ok. I'm not sure I like the fact that the strut would be lower (Inducing a slight rake would be cool though). So, what you have written has me asking a few questions...
I get the fact that I need to relocate the strut mounts in order to attain the correct allignment etc for the rear end, and that this causes an interference with the spring on the strut. What I don't understand having not seen an 88 is what is the difference that causes this interference fit? Is the shape of the 88 frame different in this area (I was told they were pretty much the same) or is the wheel well area different on the 88 or both? I like the idea of the stock looking upper end though. Also, I have the 88 struts as well...could these give me some advantage? They don't look a lot different in legth or spring diameter but I'll check them closer as I go along here.
Chay |
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86 SE 3.4
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Dr.Fiero
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Posted: 07 April 2008 at 5:30pm |
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By the strut being lower, I mean it would simply start off lower in the travel of the piston. Doesn't matter anyhow.
The stock position of the 88 strut is further inboard, and sits forward of an early car (it looks the same, just sits in a different location in space). To get the 88 strut to sit in the correct position of an early car strut tower, you need to go into a coil over - since any stock coil would be too large to fit otherwise. Ok, here's a shot of my relocated strut tower:  You can see the circled areas, red was where it started, and in green where it is now - this at least shows the relative positions of the two , and how BUTT UGLY it ends up being! Here's what the kit, and coil overs looks like (boy am I glad I took all these shots over the years):  That explain it better? |
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CFoss
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Posted: 07 April 2008 at 6:50pm |
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I think I'm with you now.
When I get closer to doing the swap I may ask you to run a tape measure beside your relocation to help me solidify the location change. It looks very similar to what I found in a pic in this article: http://www.martinwhite.name/fiero/88cradle/index.html By lower in 'the piston' I supect you mean the height is adjustable somehow (I'm new to struts with coil overs). Anyway, I'll put the stuff together on the ground and figure it out. I have some reading to do. I have to admit, I'm kind of on the fence. It's only $300 bucks for the pre engineered version, and it would save a lot of time, even if it's a bit ugly. I get where you're coming from though. We'll see how much time it takes to figure out. Too much time and I'll just get the kit and move on to driving the car! I see that the strut shaft comes through the tower by about 1" or so it looks in your pic. I guess then if I made a plate which relocates forward, and in, and down then it would need to be about 1-1.5" below the current tower level, and then as you suggest, drill a large hole in the existing tower to access the nut where the shaft comes through it. Comments? Chay |
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86 SE 3.4
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Dr.Fiero
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Posted: 07 April 2008 at 7:43pm |
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What you could also do to save SOME of the engineering, is take the Held kit, and use it as a starting point. Just make my 'upper plate', and graft it onto the Held kit. Then you keep your stock appearance, but still get the relocation.
To make up for the (arbitrarily say 2" lower position) you just get 2" shorter springs. If it's 1.75" lower, you get a 2" shorter spring and twist the ring up .25" until you're level (or down, or whatever it takes). Other bonus, if you add something that makes a corner heavy, you can twist it up/down to compensate. |
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CFoss
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Posted: 09 April 2008 at 5:28pm |
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Ok, got it now.
I read a 'make your own coil overs' thread on Pennock's and now I understand that the ride height is determined by the spring length and the shock comresses to that height. I'll have to figure out the travel length in the shock...However much I remove off the height will make it that much closer to bottoming out. Chay |
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86 SE 3.4
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CFoss
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Posted: 09 April 2008 at 5:30pm |
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One more question...why 350lb springs? The stock ones are about 150#/inch (So I've read) so why so much heavier?? I don't have more weight in the rear end with the 3.4.
Chay |
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86 SE 3.4
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Dr.Fiero
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Posted: 09 April 2008 at 6:54pm |
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I actually have 400's! Yeah, they're stiff.... But the springs I have in the front are stupid hard as well, so I needed to balance it out (don't want one end twisting and the other not!).
I'd do 300's next time, maybe 350's. But I like a firm ride. If I want a Caddy ride... I'll go buy another caddy....  |
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Dr.Fiero
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Posted: 09 April 2008 at 6:57pm |
That'll depend a lot on which springs you use. Mine move, oh.... 1/4"-1/2" under a HARD corner! Heh... The strut piston has something like 10" of working stroke. I think you'll be OK. |
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marcelvdgn
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Posted: 09 April 2008 at 10:22pm |
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John..... whats your opinion on using the standard 86/87 location for the strut top of a SE coupe with the 88 lower suspension and cradle. i know the geometry would change and possibly the ride, but willl there be some interference?????? problems???? Marcel |
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Marcel 86SE V6 Auto
85SE V6 Auto 85 2m4 soon to be sleeper 3.8sc 5 speed |
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Dr.Fiero
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Posted: 10 April 2008 at 7:19am |
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Frankly, I don't think it would work.
As you say, even if you COULD ram it in there, you just killed the caster setting, and made it about 15* positive camber! Doubt you could adjust that out. |
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Borteep
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Posted: 10 April 2008 at 3:20pm |
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At that point I would wonder why you were bothering with the switch to begin with. The whole point with going to 88 suspension is that it has improved geometry... so if you completely compromise that improved geometry by mounting it wrong...
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marcelvdgn
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Posted: 10 April 2008 at 10:19pm |
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After reviewing John's photos i realized the extent of the geometric changes moving the top of the strut tower. (using the stock 84/87 position wouldn't work well.) hey just thinkin outload, and this is what this group is all about, its all good!!! M |
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Marcel 86SE V6 Auto
85SE V6 Auto 85 2m4 soon to be sleeper 3.8sc 5 speed |
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Dr.Fiero wrote: