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SUNNY Z

Ford 8.8 IRS Conversion

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SUNNY Z:

 

Looks like the best bet is the later year Cobra differentials. Research first then invest if they spec out OK.

 

Except that they cost nearly double what the explorer diffs do, and have probably been beaten 10x harder.

 

I started some mock up tonight with my explorer diff cover. I found that the mounting bolt holes are spaced roughly 14" apart, and that makes them fall nearly dead-center with the uprights that support the rear of the A-arm (not sure of term).

 

Here's a picture of as high as I can get it without clearancing the frame.

 

2012-10-04_21-05-47_182-1.jpg

 

It does have large ears on the cover (rear mount) though, so the 4 bolts on the caps for the a arms would have to be removed to remove the diff... Not a big deal at all.

 

2012-10-04_21-06-04_612.jpg

 

 

 

Another thing to note is that the case is within 1/8" as thick as the stock R200 case. However, since the R200 case mounts to the mustache bar, the R200 sits further back. I will have to wait until I get a diff in my hands to see how much of an issue that will be - same with the height. I'd guess that I will have to section the frame a little bit to get clearance above the diff.

 

It also might be a better bet to go with a cover that would allow you to mount the diff to the mustache bar, instead of through the uprights, with a spacer in between those and the mustache bar, as would have to be done with this setup. I also have visions of a modified upright setup, so that I could still mount the diff to the mustache bar, and be as far back as it needs to be.

 

Heres a super rough 2 minute sketch of what it looks like now (minus frame sectioning of course)

 

2012-10-04_21-59-13_558.jpg

 

And now with a "modified" upright setup. Probably use something like 1" heavy wall tubing. There will of course still be the cross brace in the lower area that I left out of both drawings. This kind of negates any benefit of the explorer cover,but its a thought.

 

2012-10-04_22-05-05_85.jpg

 

What do you think? I'm open to other ideas here as well. I'll know LOTS more once I pick up a diff and can see how the axles align (front back, up down), and then I'll be able to make some better decisions.

 

This cover might be better suited.

 

211_8_8IRS_Cobra_Mustang_Super_Coupe_Rear_Differential_Cover_Girdle.png

Edited by SUNNY Z

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Your idea of modifying the "uprights" to allow the differential cover to engage the mustache bar (via spacers of suitable shape) is a good one. But I'd worry about retaining (and ideally, improving) the strength of those "uprights" - something not yet attained in your second sketch.

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Your idea of modifying the "uprights" to allow the differential cover to engage the mustache bar (via spacers of suitable shape) is a good one. But I'd worry about retaining (and ideally, improving) the strength of those "uprights" - something not yet attained in your second sketch.

 

As I said, thats just what I got from looking at it for 10 minutes in the garage last night. I'm scheming a lot of different ideas right now. One of which includes leaving the uprights untouched, and welding a mounting apparatus to the mustache bar to accomodate a cobra style cover..... idk yet.

Edited by SUNNY Z

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The Miata rear suspension left and right lower A-arm support members are not interconnected under the car. So building an interconnect is eminently useful. The S30 suspension does not suffer from this problem.

 

Has anyone tried welding brackets to the mustache bar? As it is a form of spring-steel, I wonder if the welds would be suitably strong and whether the heating would not have deleterious consequences for the elastic properties of the mustache bar. But if welding brackets to the mustache bar does indeed work, it would be an elegant solution.

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This is a suggestion. Why not take the mustache bar to a metallurgist in your town and find out what grade steel it's made of and the hardness. They can recommend if welding will hurt it or not and perhaps it can be reheated (specific temperature) after your welding to re-leave any stresses. From reading other comments about drilling into the bar it is quite hard and is a SOB to get through it. One thing is certain, as soon as heat goes into the areas of your weld you loose the spring properties in those areas and may be prone to cracking and failure. However as I mentioned, you may be able to retemper the bar once your done welding to get it back some of the spring properties. Only someone such as a metallurgist can give you a straight and accurate answer.

 

Danno74Z

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Spent a little while doing measuring and scheming while I was rebuilding a CV axle and filling the diff before reinstallation.

 

So I came up with more chicken scratches. ... Can you tell I was doing CV things? (grease)

 

2012-10-08_21-32-33_660.jpg

 

This drawing is to scale- except for the frame portion of the car. Disregard any lines with x's through them. Sorryi its a mess, but this is the easiest way to convey my ideas at the moment.

 

So this is a drawing of the uprights (obviously). I'm thinking I'm going to have another set cut from 1/4" plate from my waterjet connection, when I get a good design.

 

The hole with the "+" in it is where I would cut a circle out of the upright, and install a sleeve, with a poly bushing (just an idea to make it a little less harsh and transfer less vibration). That is also just a tentative location of the mounts - not sure as i don't have a diff yet.

 

The R200 cover, and the 8.8 cover are both 3" thick from the mounting face, to the gasket face. The only difference being that the 8.8 has a larger ring gear, and will likely shift the carrier ~1/2" forward. I am thinking that I could make the upper horizontal portion of the upright longer, which would shift the "mount" further back, and then just accommodate at the bottom for the same amount.

 

The front face of the uprights are within 1/4" of the front face of the mustache bar, because it curves in in the center. Essentially with this design, the mustache bar would be completely eliminated and removed, thus putting more load on the uprights, and me wanting it thicker.

 

The bottom drawing is kind of what I have in mind with the "sleeve" idea. For those of you that aren't aware, THIS SITE is awesome for individal bushings.

 

 

/braindump

Edited by SUNNY Z

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Had another idea today while I had the car in the air on a buddy's lift.

 

I'd either like to talk to TTT about this, or just buy a pair of his "backing plates" and change the design.

 

It has ALWAYS bugged me that the rear wheels on an S30 are offset to the front by over an inch. Riddle me this: Axle angles aside ( I'll be dealing with this when I mount the 8.8), Would it be possible to take a backing plate similar to T3 design, and add say an inch to the area where the rear strut mounts, and keep the lower mount in the same place. That way the strut mount and the LCA mount are in the same place, but the wheel is moved back!?

 

T3 backing plate in reference:

 

TTTR230-1.png

 

Handy exploded view of Z32 rear suspension - NVM the blue circles - stole the pic.

 

sp32-210.gif

 

 

This would achieve several things:

- Wheel moved back, so more tire clearance!! (and be centered for us OCD ppl)

- Donkey D!ck outer stub axles (and upgrade options)

- 5 lug (good or bad)

- Bigger brakes (good)

 

 

I still think 550 is a bit steep for just the backing plates.... ho hum.

Edited by SUNNY Z

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Honestly, I prefer the look of the wheel forward in the wheel well. I've seen a few with centered rear wheels, and it just doesn't look right. FWIW, I consider myself pretty OCD, but some things don't need "correction". ;)

 

There is also a change in weight distribution when you move an axle forward or rearward, though the small change incurred in this case, may not have that great of an effect.

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Honestly, I prefer the look of the wheel forward in the wheel well. I've seen a few with centered rear wheels, and it just doesn't look right. FWIW, I consider myself pretty OCD, but some things don't need "correction". ;)

 

There is also a change in weight distribution when you move an axle forward or rearward, though the small change incurred in this case, may not have that great of an effect.

 

#jdm ;)

 

Obviously you've never tried to get a 26" or larger tire on a lowered car. You'd probably cry if you saw how much I had to cut/ beat my inner fenders to make things fit.

 

 

Keith - Not really NEEDING the 28's yet, but I'd like it to be a possibility. More about the slicks growing enough that they rub (taking a sledge with me to the track this time). They might grow a little bit more around 130 than at 100. I'd have to rake my car out so far as it sits to get a 28 under it, I don't think I could be caught driving it.

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There are a couple of S30s in Oz with GM IRS diffs (i.e. Pontiac GTO and G8 to you). Each is quite different in how they are mounted but here are a few thoughts about both which might assist.

 

Use an adaptor plate from the diff cover to new or existing moustache bar, or

Weld a block of aluminium to the cover and drill and tap new mounting holes.

 

Modern diffs a nearly always much much shorter than S30 ones so the front mounts are difficult to design. I initially made some cantilever brackets but I am abandoning that set-up in favour of fitting twin support rails running from the rear diff cross-member to the front diff cross-member (the one with the exhaust cut-out). I have removed that cross-member but I shall be refitting it with the new set-up.

 

I can’t show you photos of the new set-up but I have added the rail to an old photo to illustrate the point. There is insufficient room for straight rails so you either have to bend round tube ot notch out some rectangular tube.

 

I have also machined an adaptor for the GM CVs to Datsun outer stub.

 

Hope I haven't confused you.

post-1266-082918500 1350518619_thumb.jpg

post-1266-097956400 1350518633_thumb.jpg

post-1266-083574900 1350518757_thumb.jpg

post-1266-060063000 1350518791_thumb.jpg

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