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3800 engine swap bushings and mounts? by johnguzman1212
Started on: 01-02-2015 01:17 AM
Replies: 7 (1111 views)
Last post by: Darth Fiero on 01-05-2015 01:47 PM
johnguzman1212
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Report this Post01-02-2015 01:17 AM Click Here to See the Profile for johnguzman1212Click Here to Email johnguzman1212Send a Private Message to johnguzman1212Edit/Delete MessageReply w/QuoteDirect Link to This Post
ok im doing a 3800 sc series 2 swap in my 87 fiero lambo from a 97 riviera. I bought the red poly cradle bushings. im currently sending in my pcm to gm tuners. can I trust them? next im going build my motor mounts or buy them from someone here. im doing solid mounts, so does this mean the motor mounts with the rubber sandwhiched in between or solid bolt to a custom cradle bracket? im confused I need some help anyone?
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olejoedad
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Report this Post01-02-2015 09:25 AM Click Here to See the Profile for olejoedadClick Here to Email olejoedadSend a Private Message to olejoedadEdit/Delete MessageReply w/QuoteDirect Link to This Post
gmtuners is very trustworthy.
Do not solid mount the 3800 unless you are building a vibrator.
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nosrac
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Report this Post01-02-2015 12:51 PM Click Here to See the Profile for nosracSend a Private Message to nosracEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by johnguzman1212:

ok im doing a 3800 sc series 2 swap in my 87 fiero lambo from a 97 riviera. I bought the red poly cradle bushings. im currently sending in my pcm to gm tuners. can I trust them? next im going build my motor mounts or buy them from someone here. im doing solid mounts, so does this mean the motor mounts with the rubber sandwhiched in between or solid bolt to a custom cradle bracket? im confused I need some help anyone?


Since you are sending your PCM to GM tuners check out his website on how to make your own mounts. Also, Fierorog on this forum makes swap brackets for use with Rodney Dickman poly mounts.

http://gmtuners.com/

http://www.fiero.nl/forum/F.../HTML/068855.html#p0

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Darth Fiero
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Report this Post01-02-2015 12:59 PM Click Here to See the Profile for Darth FieroClick Here to visit Darth Fiero's HomePageClick Here to Email Darth FieroSend a Private Message to Darth FieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
The stock Fiero 84-87 front cradle bushings made very good engine/trans mounts; but they are out of production and are no longer available. I've been trying to get the Fiero Store to reproduce them, but it does not appear as though they are interested.

What's available now, that I have been able to find, are rubber control arm (suspension) bushings like what some other guys on here are using. But they are made of a harder rubber compound (than the Fiero cradle bushings were) that don't isolate engine vibrations near as well. They are still better than poly bushings, however.

There are several stock rubber engine mounts available from a host of applications that can be used to make custom engine conversion mounts. But the problem with many of these is they aren't that strong and the likelihood of them being pulled apart in a supercharged 3800 application is quite high. Hence the reason why I used the Fiero cradle bushings as long as I could - they could not be pulled apart the way I designed them for use in this application.

Perhaps if we could get more people to lobby the Fiero Store to get them to reproduce the rubber Fiero cradle bushings, they would start making them which would make them available for use again as an engine conversion mount.

-ryan

------------------
OVERKILL IS UNDERRATED

Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com

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johnguzman1212
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Report this Post01-02-2015 08:41 PM Click Here to See the Profile for johnguzman1212Click Here to Email johnguzman1212Send a Private Message to johnguzman1212Edit/Delete MessageReply w/QuoteDirect Link to This Post
the info I see here makes no sense I was told to use poly cradle bushings and solid motor mounts or alum cradle bushings with rubber motor mounts but not both so I have the poly cradle bushings so now I use rubber motor mounts? bty I thought that was correct in the first place. good idea to use a arm bushings never thought of that I just want to use something very universal and common. now what? gm tuners it is thanks guys
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Darth Fiero
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Report this Post01-03-2015 03:39 PM Click Here to See the Profile for Darth FieroClick Here to visit Darth Fiero's HomePageClick Here to Email Darth FieroSend a Private Message to Darth FieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by johnguzman1212:

the info I see here makes no sense I was told to use poly cradle bushings and solid motor mounts or alum cradle bushings with rubber motor mounts but not both so I have the poly cradle bushings so now I use rubber motor mounts? bty I thought that was correct in the first place. good idea to use a arm bushings never thought of that I just want to use something very universal and common. now what? gm tuners it is thanks guys


I've been doing Fiero swaps for the better part of 20 years. The problem with the 3800 V6 engines is they are 90 deg V6's which don't run very smooth. In contrast, 90 deg V8 and 60 deg V6 design engines run very smooth and you can use those with poly/solid mounting systems without giving yourself a headache driving the car a lot.

My experience doing 3800 swaps over the years has taught me the best mounting solution is to use rubber engine and transmission mounts with rubber cradle bushings (only applies to 84-87 Fieros since 88 Fieros had a solid-mounted cradle, with no provisions to place bushings of any kind between the cradle and body).

If you are doing a Fiero 3800 swap and substitute poly or solid bushings for rubber in either the engine/trans mounts or the cradle mount positions, you are going to pay for it in increased engine vibrations being transmitted to the body (and passenger compartment) of the car. I don't care what you've read elsewhere - take my word for it. Solid mounts are the last thing you want. The popular polyurethane bushings that are sold just about everywhere are so hard of a formulation they are almost as bad as solid aluminum mounts. I hear you can custom order a kit to mix a much softer polyurethane bushing (to mold yourself), but I have also heard that kit is not cheap at all.

[This message has been edited by Darth Fiero (edited 01-03-2015).]

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Tuna Helper
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Report this Post01-05-2015 10:53 AM Click Here to See the Profile for Tuna HelperClick Here to Email Tuna HelperSend a Private Message to Tuna HelperEdit/Delete MessageReply w/QuoteDirect Link to This Post
What about using dogbone bushings in place of the cradle bushings?
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Darth Fiero
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Report this Post01-05-2015 01:47 PM Click Here to See the Profile for Darth FieroClick Here to visit Darth Fiero's HomePageClick Here to Email Darth FieroSend a Private Message to Darth FieroEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Tuna Helper:

What about using dogbone bushings in place of the cradle bushings?


I thought about that too. But most that I looked at are odd sized bushings and also are too soft for the application. Remember, a bushing used in this application needs to be able to support the full weight of the engine + the amount of torque being applied to it when you step on the gas. Dog bone bushings aren't designed to hold the weight of the engine and, due to their stock location (when used as dog-bones) being further from the axle centerline, they don't have to withstand as many ft/lbs of torque being applied to them as they would when located closer to the axle centerline which they would be when used as an engine mount.

Edit to add: finding suitable bushing material for this application is a challenge. You want something soft, but not so soft that it allows for a lot of engine movement as torque is applied. Dog-bone bushings, by nature, allow for a lot of powertrain movement which usually doesn't work well in engine swap applications, especially if clearances are tight between engine/trans components and the compartment in the Fiero.

The stock Fiero 84-87 front engine cradle bushings worked very well because they were not too soft but they are not as firm as control arm bushings or poly bushings. They were originally designed to support the weight of the engine+trans+cradle, and were designed to deal with the torque of the powertrain being put on them during acceleration.

[This message has been edited by Darth Fiero (edited 01-05-2015).]

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