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What is the consensus?

Centerline, Vick Auto transmission mount?
 

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consensus is to measure it first before you install it, and turn down the OD to 64mm if its too large.
 
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But Mad North-Northwest
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If you race, do what you like. If you plan on streeting the car, the advice on filling the voids or the poly mount insert are really bad ideas.

Honestly I think the Powerflex insert is designed completely wrong, and that nobody should use it. Look at the stock mount, you see how the center hole is offset low? With the weight of the transmission on it, the center hole moves up so that it's more centered in the bushing. It's also got room to move up and down on the soft bushing and absorb the vibrations.

Now look at the poly insert. This fills the area above the center hole with solid poly and basically locks it in place. When you load it up you've got the center hole pushing (hard) on solid poly, which is then pushing (hard) on the outside of the bushing. This is why you get nasty vibrations. And worse, it holds the mount in the wrong place. The inner hole is no longer centered in the bushing when loaded, so you've changed your driveshaft alignment.

It appears to have been designed by someone who did not understand how the bushing was supposed to work. It's a bad idea executed poorly, and I've never seen anyone on the BB who was happy using one.

For a street car I would strongly recommend just installing the mount as-is. If you must, you can try inserting a couple of pieces of rubber hose into the upper void, that will stiffen it slightly (and hopefully not to the point of causing vibration). But with a fresh stock transmission mount and good engine mounts I've never had issues with excessive transmission movement and it keeps the driving smooth.


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If you race, do what you like. If you plan on streeting the car, the advice on filling the voids or the poly mount insert are really bad ideas.
The liquid polyurethane typically used as filler is not that hard. It still flexes, and there is a lot of movement left in the remaining rubber material. The result poly/rubber mix is not nearly as solid as a powerflex mount.

That said... I was totally going to fabricate my Delrin mount with an offset hole. Thank you so, so much!
 

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But Mad North-Northwest
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Like I said, if someone wants it stiffer just stick a couple of pieces in heater hose in the void. You can tune the stiffness that way easily in the car by adding more/less hose.

Delrin, well...it's your teeth, man. I'm not sure that even for racing there's an advantage of having zero give there: you don't want the transmission moving too much, but you also want something to damp some of the engine vibrations. Maybe start with something softer (like the hose idea) and work your way up.
 

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i have installed a polly insert on a few car.. no added vibration...some people feel what they want to feel.. as a tech after we work/ repair a car.. some customer come back and complane about something we did not work on.. you fix one problem,, that perhaps was overshadowing a diff problem that was there in the first place... we /I fixed some front brakes on a customers car due to vibrations ( they were close to worn out ) fixed the brakes i bedded them in correctly.. customer took the car home, only to show up a few days later.. saying is still has a vibration.. the dampners were oem 9 years old..... have any of you fix a part of your car, only to find out there was different problem, hiding in the car?
I am not talking about those customers, I am talking about reality. I had those customers at my shop also.
 

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Delrin, well...it's your teeth, man. I'm not sure that even for racing there's an advantage of having zero give there: you don't want the transmission moving too much, but you also want something to damp some of the engine vibrations. Maybe start with something softer (like the hose idea) and work your way up.
Been there, tried it all. Have a friend with a lathe that made his own Delrin mounts for his E30, and the car doesn't drive bad... So I let him have at it.

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Greg's right guys-- there are testimonies here on the BB about filling in those spaces with poly or other harder material. You will get more vibration, according to others' experiences. If it's a track car, then I suppose that's no issue.
I have a solid aluminum trans mount and delrin for the motor mounts. There’s more vibrations transmitted than rubber mounts, but I don’t find it nearly to be all that noticeable. Perhaps my lightened/balanced rotating assembly helps a bit.

One thing you don’t want to do is only stiffen some of the mounts (only transmission or only motor)- that is likely to be worse than a firm mount all around.
 

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If you race, do what you like. If you plan on streeting the car, the advice on filling the voids or the poly mount insert are really bad ideas.

Honestly I think the Powerflex insert is designed completely wrong, and that nobody should use it. Look at the stock mount, you see how the center hole is offset low? With the weight of the transmission on it, the center hole moves up so that it's more centered in the bushing. It's also got room to move up and down on the soft bushing and absorb the vibrations.

Now look at the poly insert. This fills the area above the center hole with solid poly and basically locks it in place. When you load it up you've got the center hole pushing (hard) on solid poly, which is then pushing (hard) on the outside of the bushing. This is why you get nasty vibrations. And worse, it holds the mount in the wrong place. The inner hole is no longer centered in the bushing when loaded, so you've changed your driveshaft alignment.

It appears to have been designed by someone who did not understand how the bushing was supposed to work. It's a bad idea executed poorly, and I've never seen anyone on the BB who was happy using one.

For a street car I would strongly recommend just installing the mount as-is. If you must, you can try inserting a couple of pieces of rubber hose into the upper void, that will stiffen it slightly (and hopefully not to the point of causing vibration). But with a fresh stock transmission mount and good engine mounts I've never had issues with excessive transmission movement and it keeps the driving smooth.


View attachment 1711541 View attachment 1711542
I tried fitting the powerflex bush and the noise and vibration was excessive, made for very unpleasant driving without any benefit
 

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I tried fitting the powerflex bush and the noise and vibration was excessive, made for very unpleasant driving without any benefit
There is a reason for the stock mounts. A cross between performance and comfort while driving. I have made delrin bushings etcetera for my race cars but on the street, not so much fun
 
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These are the so called 'heavy duty' mount. They are just early type. Many of the cars I worked on were track cars or week end warriors. For me this is perfect compromise. No issues with vibration.
If I was changing one on say a stock duetto running on original tires and suspension, or something original and delicate then I would fit what ever was original.
Also a picture of the factory tool thanks to alfa bb and Tubut 2010.


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i have installed a polly insert on a few car.. no added vibration...some people feel what they want to feel.. as a tech after we work/ repair a car.. some customer come back and complane about something we did not work on.. you fix one problem,, that perhaps was overshadowing a diff problem that was there in the first place... we /I fixed some front brakes on a customers car due to vibrations ( they were close to worn out ) fixed the brakes i bedded them in correctly.. customer took the car home, only to show up a few days later.. saying is still has a vibration.. the dampners were oem 9 years old..... have any of you fix a part of your car, only to find out there was different problem, hiding in the car?
Yes. My trans mount is shot n new one is in freezer.
Both motor mounts were loose, one broke, exhaust cracked and exhaust nuts needed tightening. Assuming all related to extra vibration from bad mount.
Best to get in there n check it all when replacing it
 
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Kind of surprised there isnt a two piece delrin version like in the rear t bar. Be a lot easier to change out
 

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The liquid polyurethane typically used as filler is not that hard. It still flexes, and there is a lot of movement left in the remaining rubber material. The result poly/rubber mix is not nearly as solid as a powerflex mount.

That said... I was totally going to fabricate my Delrin mount with an offset hole. Thank you so, so much!
delin really rock hard?
 

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Yes. My trans mount is shot n new one is in freezer.
Both motor mounts were loose, one broke, exhaust cracked and exhaust nuts needed tightening. Assuming all related to extra vibration from bad mount.
Best to get in there n check it all when replacing it
heres a thought..on the motor mounts... before you install new one,, remove the rubber part ( un bolt it ) from the steel engine/ bodyshell mounts.. take the rubber part to home depot.. plumbing section. and find a peice of plastic pipe.. that is a snug fir around it.. and take it home and cut the plastic pipe the same size a the rubber part.. s;;ip it on( silicone glazing to glue it on, if a little loose, then bolt it back togeather.. install them on the car.. as the engine weighes down on the rubber, it will expand into the plastic pipe.. a ,ore soild mount... paul spurell racing sold aluiumn ones a whole back but not any more.. nice cheap fix to make the mount stronger
 

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So looks like OKP has a kit to do fill in the holes on the mount with delrin spacers and includes delrin spacers for $35
Took advantage of Black Friday 20% discount to buy all the rubber bits for the Super and added a kit to see how it looks
 

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But Mad North-Northwest
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That’s not delrin, Pinshaw, that’s polyurethane. It looks like a blue version of the Powerflex insert.

I’ve never seen anyone on the BB who was happy with the trans mount insert but, who knows, maybe you’ll be the first.
 
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