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solid motor mounts - poly or rubber trans mount ? #2743576
02/16/20 02:27 PM
02/16/20 02:27 PM
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north of coder
moparx Offline OP
"Butt Crack Bob"
moparx  Offline OP
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north of coder
as the title suggests, when using solid engine mounts [whether motor plate or block ears - this is big block if it matters], what is the preferred automatic transmission mount ?
polyurethane or rubber, and why ?
as always, TIA guys ! bow up
beer

Re: solid motor mounts - poly or rubber trans mount ? [Re: moparx] #2743590
02/16/20 02:43 PM
02/16/20 02:43 PM
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State of confusion
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Thumperdart Offline
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I went with the PST urethane mount and wish I would of done it years ago after the rubber would deteriorate after a few years and sag......


72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
Re: solid motor mounts - poly or rubber trans mount ? [Re: Thumperdart] #2743597
02/16/20 02:50 PM
02/16/20 02:50 PM
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North Central, Indiana
Roughbird72 Offline
pro stock
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North Central, Indiana
I've been using solid engine mounts and a poly trans mount for years.
Thinking about going back to rubber isolator and a strut on the engine, getting old I guess whistling


72 Plymouth Roadrunner 11.08@123.25
Re: solid motor mounts - poly or rubber trans mount ? [Re: moparx] #2743613
02/16/20 03:27 PM
02/16/20 03:27 PM
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A shed in England
Tig Offline
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A shed in England
Ears, a poly 'box mount and fore / aft limiters. Been this way since I installed a 440 in '94up


'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials.
9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge.
RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
Re: solid motor mounts - poly or rubber trans mount ? [Re: moparx] #2743734
02/16/20 08:29 PM
02/16/20 08:29 PM
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Bend,OR USA
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Cab_Burge Online work
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Bend,OR USA
Rubber on the tranny mounts as that was the only option back when I put my last car together in 2002 .
My current SP CM tube chassis car has a aluminum front motor plate with a bolt in mid plate and a rubber mount on the Powerglide tranny shruggy
I'm building a new 1965 Dart back half car that is certified to 7.50 ET but I have not dealt with the tranny mount yet, I'm thinking of using a solid front and mid plate and no tranny mount on either a Powerglide or a all out Pro Trans 727 SS trans shruggy

Last edited by Cab_Burge; 02/16/20 11:02 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: solid motor mounts - poly or rubber trans mount ? [Re: Cab_Burge] #2743791
02/16/20 10:59 PM
02/16/20 10:59 PM
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Park Forest, IL
slantzilla Offline
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Park Forest, IL
I have a motor plate and poly trans mount in my Valiant.


"Everybody funny, now you funny too."
Re: solid motor mounts - poly or rubber trans mount ? [Re: moparx] #2743807
02/17/20 12:39 AM
02/17/20 12:39 AM
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Missouri
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jwb123 Offline
super stock
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Missouri
When using solid engine mounts, you have to have some give, as the car and the chassis flexes a little. I run a poly mount, they seem to hold up the best. As mentioned the rubber ones don't hold up well. And when I was young and dumb, I tried a solid rear mount, did not work out well, kept pulling the threads out of the tail housing where the mount bolted. I have even seen solid rear mounts break a tail housing.

Re: solid motor mounts - poly or rubber trans mount ? [Re: jwb123] #2743818
02/17/20 01:07 AM
02/17/20 01:07 AM
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Alexandria, LA
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Blucuda413 Offline
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Alexandria, LA
I'm the different one, I've been using both solid engine mounts and solid trans mounts for the last 35 years. Currently running motor plate and solid PG rear mounts. The biggest engine I've run in this configuration was 650HP.

Re: solid motor mounts - poly or rubber trans mount ? [Re: Cab_Burge] #2743914
02/17/20 12:28 PM
02/17/20 12:28 PM
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Mo.
racerx Offline
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Mo.
Originally Posted by Cab_Burge
Rubber on the tranny mounts as that was the only option back when I put my last car together in 2002 .
My current SP CM tube chassis car has a aluminum front motor plate with a bolt in mid plate and a rubber mount on the Powerglide tranny shruggy
I'm building a new 1965 Dart back half car that is certified to 7.50 ET but I have not dealt with the tranny mount yet, I'm thinking of using a solid front and mid plate and no tranny mount on either a Powerglide or a all out Pro Trans 727 SS trans shruggy

Even in a 25 series chassis ,there still needs to be a poly/rubber tranny mount?

Re: solid motor mounts - poly or rubber trans mount ? [Re: racerx] #2743923
02/17/20 12:43 PM
02/17/20 12:43 PM
Joined: Sep 2003
Posts: 19,239
north of coder
moparx Offline OP
"Butt Crack Bob"
moparx  Offline OP
"Butt Crack Bob"

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north of coder
i know there should be one or the other mounts due to the risk of tailshaft damage, and i thought the poly mount might win out due to the quality, or lack thereof, of the reproduction rubber mount.
thanks for the responses guys !
beer

Re: solid motor mounts - poly or rubber trans mount ? [Re: moparx] #2743966
02/17/20 02:30 PM
02/17/20 02:30 PM
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Alexandria, LA
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Blucuda413 Offline
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Alexandria, LA
One item I didn't mention is that I run a JW trans case including a JW tail shaft housing. I'm sure there's extra strength there.

Re: solid motor mounts - poly or rubber trans mount ? [Re: Blucuda413] #2744078
02/17/20 09:37 PM
02/17/20 09:37 PM
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Ohio
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lockjaw-express Offline
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Ohio
Since I have AndyF's front Motor Plate, I used the Poly Trans Mount, but I still have dual Fore/Aft limiters...I guess time will tell.

my 2 cents...Mark

Re: solid motor mounts - poly or rubber trans mount ? [Re: Blucuda413] #2744154
02/18/20 06:25 AM
02/18/20 06:25 AM
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Mo.
racerx Offline
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Mo.
Originally Posted by Blucuda413
One item I didn't mention is that I run a JW trans case including a JW tail shaft housing. I'm sure there's extra strength there.



curios on what chassis this is in? Stock/probuilt?

Re: solid motor mounts - poly or rubber trans mount ? [Re: racerx] #2744369
02/18/20 06:08 PM
02/18/20 06:08 PM
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Alexandria, LA
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Blucuda413 Offline
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Car is 68 Notch. Everything from trans cross member to rear of car was professionaly built by Alston ages ago. Now has full cage. Had stock front suspension for years but recently changed and added Lamb struts to front frame. It's pretty stiff.

Re: solid motor mounts - poly or rubber trans mount ? [Re: moparx] #2744509
02/19/20 09:21 AM
02/19/20 09:21 AM
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Marion, South Carolina [><]
an8sec70cuda Offline
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Marion, South Carolina [><]
I use a poly trans mount. Same one has been on the car for 23 years now. I've always been told not to run a solid trans mount so you have some amount of "give", but can't argue w/ blucuda's success. up Every time I've seen someone locally try that, they ended up cracking the trans case.


CHIP
'70 hemicuda, 575" Hemi, 727, Dana 60
'69 road runner, 440-6, 18 spline 4 speed, Dana 60
'71 Demon, 340, low gear 904, 8.75
'73 Chrysler New Yorker, 440, 727, 8.75
'90 Chevy 454SS Silverado, 476" BBC, TH400, 14 bolt
'06 GMC 2500HD LBZ Duramax
Re: solid motor mounts - poly or rubber trans mount ? [Re: an8sec70cuda] #2744619
02/19/20 02:24 PM
02/19/20 02:24 PM
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Romeo MI
MR_P_BODY Offline
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Romeo MI
ALL cars flex... any two points is a straight line buy if you add a third point it doesnt mean its still a
straight line.. same thing goes on a car.. you need to have one point that will give..if not you will break
the weakest point.. I run the front motor plate and a mid plate with a rubber trans mount
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