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1988 vs 1985 Cradle - Engine and Trans Mount Locations by Ravant
Started on: 03-27-2014 10:26 PM
Replies: 12 (1351 views)
Last post by: Ravant on 04-01-2014 11:44 AM
Ravant
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Report this Post03-27-2014 10:26 PM Click Here to See the Profile for RavantSend a Private Message to RavantEdit/Delete MessageReply w/QuoteDirect Link to This Post
I've gone over how to swap an '88 cradle under an '85 V6 a few times, trying to get a handle on what precisely is different between the cradles. Without having them in front of me at the moment, (I intend to soon! But I don't want to wait 'til last minute to start gathering info and doing research.), I can't directly compare them to get a definitive changelog. SO! My question is this:

Given the various swaps out there (3800, 60*V6, Ecotec) and the various mount options sold by different vendors for each, what I'm trying to discover is how many of those swap mount options are "locked" to a given cradle?

Example: If only swapping the cradle on a stock 2.8 V6, you need the 1988 driver's side engine mount bracket and mount as well as the passenger side engine mount according to this guide.

So. Of the swaps (3800, 60*V6, Ecotec), how many of them even use the same driver's side engine mount bracket as the 2.8 on an '88 cradle?
Other than the driver's side engine mount, what other engine/trans mounts are different between 1985 and 1988?

I know about the fabrication for inward relocation of the strut mounts, brake changes (parking brake, brake lines, rotors, calipers), exhaust changes and coolant line changes. Those don't really concern me as 1) My current rear brakes need a full overhaul, 2) no matter the engine swap, I'm going full custom exhaust, 3) Coolant lines are flexible, but 28 years old and need replaced. So, yes, it's a bit of work, but I figured since I'm swapping engines/trans, it's a worthwhile endeavor.
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Gall757
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Report this Post03-28-2014 07:43 AM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
I think you are going to need to define "locked". I read your post 3 times and I still don't get it. All 60 degree V6 engines can be accommodated by the cradle and production 2.8 mounts. The others need custom mounts.
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Report this Post03-28-2014 07:49 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
The transmission mount locations on the 84-87 and the 88 cradle crossmembers are effectively the same (the 88 4cyl auto mono mount is an additional mount, the crossmembers on that crade are still there). The difference is on the engine mount pad where the 88 engine mount location is shifted to the front and further inboard about 1" in both directions.

Only the 60 degree V6 family uses the stock fiero 2.8 engine mount (and this mount is different between 85-87 and 88's). All other swaps use engine mounts specific to their engine family. I did modify the stock 84-87 2.8 engine mount to work with a 4.9 10+ years ago, but that isn't typical. I have also modified the 84-87 2.8 mount to work with an 88 cradle, but it does alter the placement of the engine slightly (about 1/4") side to side.

Word of caution mixing/matching mounts from multiple vendors... not everyone places the engine in the same place side/side, front/back or up/down. So by mixing 2 vendors mounts you can find yourself with an engine that doesn't sit level or square to the engine bay. Also, the side/side placement is the most critical for axle lengths, so the axles used need to be compatible with the mounts used.

For reference, here are the two cradles:

84-87:


88:

[This message has been edited by fieroguru (edited 03-28-2014).]

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Ravant
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Report this Post03-28-2014 10:16 AM Click Here to See the Profile for RavantSend a Private Message to RavantEdit/Delete MessageReply w/QuoteDirect Link to This Post
Those pictures are a massive help and really puts everything into perspective pretty readily. I'm not so much looking to mix/match from vendors, I didn't make that clear in my first post.

As far as the term 'locked', I meant: If someone makes 3800 mounts, are they mounts that are specific to the 88 cradle or are they mounts that can work on all year cradles. I'm sure that's a question for the individual vendors. My curiosity was more surrounding "If I swap to an '88 cradle, does that change my available options for prefabbed swap brackets?"
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Ravant
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Report this Post03-31-2014 11:48 PM Click Here to See the Profile for RavantSend a Private Message to RavantEdit/Delete MessageReply w/QuoteDirect Link to This Post
Bumping this for a request for more pictures!

Mind you, I should have an '88 cradle here sometime in mid-April, and I'll be able to compare side by side in person, but! I'm trying to plan things and make decisions/a budget. Does anyone have a picture of each (an '88 and pre-88) cradle, out of the car, from the front? (Basically, looking at it from the front of the car facing the back instead of top-down.) What I'm trying to see is the size of the exhaust hump on the passenger side for the '88 when compared to the '85. I've failed my google-fu training and have yet to find what I need.
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Report this Post04-01-2014 01:11 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
I don't have the photos you requested, but can tell you that the exhaust humps are about the same. Both will easily fit a 2.5" pipe (my exhaust is 2.5"). But a 3" pipe will require very careful placement.
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Ravant
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Report this Post04-01-2014 01:16 AM Click Here to See the Profile for RavantSend a Private Message to RavantEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Blacktree:

I don't have the photos you requested, but can tell you that the exhaust humps are about the same. Both will easily fit a 2.5" pipe (my exhaust is 2.5"). But a 3" pipe will require very careful placement.


Thanks. What I'm concerned about is the front crossmember height on that side. I know, for an Ecotec swap that retains AC, either you need to replace the front crossmember with Roger Thelin's crossmember, or notch that section if you have a pre-88 cradle. What I'm trying to determine is if the requirement to notch that area and reinforce below it is still a thing with the '88.
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fieroguru
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Report this Post04-01-2014 06:30 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
The front crossmembers between the 84-87 and the 88 are very similar.
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Report this Post04-01-2014 08:18 AM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryEdit/Delete MessageReply w/QuoteDirect Link to This Post
Here's a drawing of the front view of the '88 cradle with the measurements (in millimeters) you're looking for:

[This message has been edited by Bloozberry (edited 04-01-2014).]

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Report this Post04-01-2014 08:25 AM Click Here to See the Profile for BlacktreeClick Here to visit Blacktree's HomePageClick Here to Email BlacktreeSend a Private Message to BlacktreeEdit/Delete MessageReply w/QuoteDirect Link to This Post
This is the closest thing I have... not sure if it'll help or not.



That's an '88 cradle on the left, and an '87 on the right.
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Ravant
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Report this Post04-01-2014 08:43 AM Click Here to See the Profile for RavantSend a Private Message to RavantEdit/Delete MessageReply w/QuoteDirect Link to This Post
Awesome. Thanks a lot to all of you, this sheds some light. Looks like I'll still need to notch/replace. As far as which I'm going to do, I'm not sure yet. There's going to be some work. Where does everyone keep getting these technical drawings with the measurements? I'd love if I could start digging into more (preferably all in mm instead of inches. Precision!) I've got ideas but prefer working on paper first, measuring thrice and only cutting once.
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Report this Post04-01-2014 10:04 AM Click Here to See the Profile for BloozberrySend a Private Message to BloozberryEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Ravant:
Where does everyone keep getting these technical drawings with the measurements?


The two that Fieroguru posted come straight from the factory service manuals, but those are the only two drawings you'll find there. For the '88 cradle only, I created a number of drawings and posted them about halfway down the page in this thread: www.fiero.nl/forum/Forum3/HTML/000116-8.html#p302
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Report this Post04-01-2014 11:44 AM Click Here to See the Profile for RavantSend a Private Message to RavantEdit/Delete MessageReply w/QuoteDirect Link to This Post
Alright, thanks. I may have to start taking more measurements and creating images. If only because I'm eventually going to need it. Can share it with the community when I'm done.
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