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Can I switch from poly to rubber? by JCircs
Started on: 09-30-2014 09:55 PM
Replies: 9 (323 views)
Last post by: fieroguru on 10-02-2014 06:21 AM
JCircs
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Report this Post09-30-2014 09:55 PM Click Here to See the Profile for JCircsClick Here to Email JCircsSend a Private Message to JCircsEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have the WCF poly motor mounts and cradle bushings for my 87 automatic 3800 supercharged swap, I'm also using the WCF dogbone. I can't stand the vibration at idle and would like to switch back to rubber just at the mounts. Im probably in the neighborhood of 350 whp and wondering if the rubber would hold up?
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Dennis LaGrua
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Report this Post10-01-2014 10:39 AM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by JCircs:

I have the WCF poly motor mounts and cradle bushings for my 87 automatic 3800 supercharged swap, I'm also using the WCF dogbone. I can't stand the vibration at idle and would like to switch back to rubber just at the mounts. Im probably in the neighborhood of 350 whp and wondering if the rubber would hold up?

Your vibration is coming from the poly motor and transmission mounts and to a small degree from the dog bone.
Being that you have a 3800SC engine, no rubber swaps mounts were ever made for that swap. If custom rubber mounts were made to support that power they would need to be molded in a special run and would probably be cost prohibitive. Live with it, join the club, look at it as a price to pay, and enjoy the extra horsepower. Most of the time you are not idling so I look at it as a minor inconvenience.
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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 10-01-2014).]

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fieroall
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Report this Post10-01-2014 01:03 PM Click Here to See the Profile for fieroallSend a Private Message to fieroallEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have a 5 speed 3800na with WCF poly transmission and engine mounts and my vibration is barely noticeable. I would say negligible. Maybe check if the engine is centered properly before you go swapping mounts.
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JCircs
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Report this Post10-01-2014 02:21 PM Click Here to See the Profile for JCircsClick Here to Email JCircsSend a Private Message to JCircsEdit/Delete MessageReply w/QuoteDirect Link to This Post
I think the 5 speed helps, my vibration aint to bad in P. I think if I raise my idle a little in D it won't be so bad.
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Dennis LaGrua
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Report this Post10-01-2014 03:05 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
My 3800SC w 4T65eHD using all poly mounts is perfectly centered and in neutral, drive or park it chatters your teeth. Perhaps a rubber dog bone would help smooth things out a bit but it would also allow more engine movement. Might be worth a try.
When I drive my Fiero its either to a cruise night or a car show I rarely get stuck in traffic so the idling period is slight. I put up with it to enjoy the performance. On the 4.9L that I am building for cruising, it uses rubber trans mounts and poly engine mounts. I am expecting that swap to provide less vibration.
My advice to JCircs: try a rubber dog bone and see if that helps.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 10-01-2014).]

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rogergarrison
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Report this Post10-01-2014 04:33 PM Click Here to See the Profile for rogergarrisonClick Here to Email rogergarrisonSend a Private Message to rogergarrisonEdit/Delete MessageReply w/QuoteDirect Link to This Post
I put in solid and poly mounts in my V8 car. It shooks so bad, I went back to the rubber ones the same day. Wasted a whole day swapping back n forth.
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fieroguru
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Report this Post10-01-2014 05:21 PM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Sinister uses round rubber bushings for nearly all his swaps (3800 and LS4)... so it is possible to use rubber bushings and if you use the right ones, they hold the power fine.
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Dennis LaGrua
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Report this Post10-01-2014 07:12 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by fieroguru:

Sinister uses round rubber bushings for nearly all his swaps (3800 and LS4)... so it is possible to use rubber bushings and if you use the right ones, they hold the power fine.


JCircs is using commercially available WCF engine and trans mounts and the axles sized to those mounts. Darth may use rubber bushing mounts but they are his unique design and most likely not adaptable to the WCF brackets and powertrain position. I believe that JCircs is looking for a commercially available plug and play solution but none is available. . As for my swaps they live with the feel of power & extra vibration for once the car is moving there is no more vibration.
Jerry could start from scratch and fabricate new trans and engine brackets based on the Fiero mounts but I doubt if these would hold up with the power that he is making.


------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 10-01-2014).]

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bmwguru
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Report this Post10-02-2014 04:54 AM Click Here to See the Profile for bmwguruClick Here to visit bmwguru's HomePageClick Here to Email bmwguruSend a Private Message to bmwguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
Here are your options to reduce the vibration:

Remove the performance camshaft and give it to me

increase the idle speed by 25 rpms until you reduce the vibration (but don't go too high or you will have other issues develop)

increase the ignition timing at idle to reduce the vibration

make sure that the engine is sitting correctly on the cradle. The two automatic swaps I had done needed the cradle to be slightly notched to clear the transmission from rubbing.

I solid mount the cradles in my pre 1988 cars and use poly mounts. Even the VR6 uses solid engine mounts because the intake is so big that I can't have it move or it will crack the intake. There is no vibration.

Keep in mind that you disconnected the balance shaft with that timing chain, so a little more vibration is to be expected, but that is more noticeable at 2-3k rpms.

Dave

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www.hausofguru.com

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fieroguru
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Report this Post10-02-2014 06:21 AM Click Here to See the Profile for fieroguruSend a Private Message to fieroguruEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Dennis LaGrua:
JCircs is using commercially available WCF engine and trans mounts and the axles sized to those mounts. Darth may use rubber bushing mounts but they are his unique design and most likely not adaptable to the WCF brackets and powertrain position. I believe that JCircs is looking for a commercially available plug and play solution but none is available.



The WCF mounts are just basic round tubes so its a matter of finding a rubber control arm bushing that is the right length and right ID to fit the current mounts. If he found one with a slightly smaller OD, he could have some sleeves made to fill the gap. He could also cut the tubes off and have new ones that fit a rubber control arm bushing bushing welded on. Lots of options, just depends on how much time/effort he wants to put into getting back to rubber mounts.
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