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Rennline heavy duty transmission bushing

Phil 997

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5 Dec 2015
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16,547
For the past few weeks my car has had a nasty vibration at around 3200rpm and lesser vibration at other revs this was not a rattle of trim or anything as you could feel it through the seats, after trying lots of different fixes finally it seems to have been located at the transmission mount , which had Function first yellow sport inserts fitted the inserts were removed and it seems to have sorted the vibration a long hoon tomorrow will confirm this . So I have several questions
1/ why after 12 months of being fitted would these suddenly cause a vibration .
2/ has anyone used the rennline heavy duty transmission bushing on their tiptronic and if so your thoughts please.
It looks like the rennline are a complete bushing rather than an insert they say they are 25% firmer than the stock bushing.

your thought are appreciated as I did like the improved transmission feel of a firmer bushing until the vibration started. :thumb: :thumb: :thumb:

http://www.rennline.com/HD-Heavy-Duty-Transmission-Bushing/productinfo/S-13002P/
 

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That`s a shame Phil, you`ve been over the moon with it for 12 months :sad:

Possibly the " plastic " degrading and getting hard over time :dont know:

Will be following this thread as I`m about to replace my engine and gearbox mounts on the 996 as I can`t see any evidence of them being replaced in the history file.
 
kurlykris said:
That`s a shame Phil, you`ve been over the moon with it for 12 months :sad:

Possibly the " plastic " degrading and getting hard over time :dont know:

Will be following this thread as I`m about to replace my engine and gearbox mounts on the 996 as I can`t see any evidence of them being replaced in the history file.

I know Kris , I coundn't speak highly enough about them , I was thinking the same that somehow the material degraded and lost the give. whereas the rennline ones look like a complete bush alternative so might be the solution I am looking for ,sort of stock but a bit firmer. but wanted to know a bit more before pushing the button on them. :thumb: :thumb: I have been pleased with the rennline adjustable semi solid engine mounts so I am hoping the transmission parts will be as good. :thumb: :thumb: :thumb:
 
Heat hardening
:?:
 
Frenchmeister said:
Heat hardening
:?:

Think you could be right mate :thumb: :thumb:
 
Phil, the vibrations started after you had the engine lowered to fix the AC pipe if memory serves me correctly. Surely it has to be linked with this..... - do you think during the process of dropping the engine, a strain was placed on the transmission mount such that it may have dislodged the insert or somehow adversely affected the mount!

It just seems too much of a coincidence that your vibrations started after the engine was lowered, and dropping the engine is surely going to produce an unorthodox effect on the transmission mount.
 
Hi Phil

I am sorry I don't have the answer and after fitting semi solid engine mounts have a similar issue at around 3000 rpm.

But I would be careful with Rennline mounts as I found their engine mounts harsher than the RSS ones I am currently using.

In my case I also have a LWF which has been balanced but it was unbearable with Rennline engine mounts which surprised me as I have previously had a solid flywheels with RSS mounts without an issue.

I understand the principle of why stiffer mounts cause more vibration but not why it always seems evident around the point varicam kicks in.
 
monster said:
Phil, the vibrations started after you had the engine lowered to fix the AC pipe if memory serves me correctly. Surely it has to be linked with this..... - do you think during the process of dropping the engine, a strain was placed on the transmission mount such that it may have dislodged the insert or somehow adversely affected the mount!

It just seems too much of a coincidence that your vibrations started after the engine was lowered, and dropping the engine is surely going to produce an unorthodox effect on the transmission mount.

I discussed that Tim with the guys who did it and they said the transmount etc was dropped as a complete unit with the engine as the tip mount is different to the manual one, so it couldnt have dislodged.
So the only conclusion I can come too is that it was just a coincidence that the FF insert became brittle or warped etc at the same time as the engine was dropped :?: :dont know:
 
Nimrod said:
Hi Phil

I am sorry I don't have the answer and after fitting semi solid engine mounts have a similar issue at around 3000 rpm.

But I would be careful with Rennline mounts as I found their engine mounts harsher than the RSS ones I am currently using.

In my case I also have a LWF which has been balanced but it was unbearable with Rennline engine mounts which surprised me as I have previously had a solid flywheels with RSS mounts without an issue.

I understand the principle of why stiffer mounts cause more vibration but not why it always seems evident around the point varicam kicks in.


I agree with your thoughts of why only at certain RPM :dont know: strangely I have no issue with my rennline semisolid engine mounts and find them quite compliant but have never been in a car with RSS to compare .
at the moment I think I will leave well alone as after a good hoon today I can confirm all is sorted, vibration gone, so it must have been the FF trans mount inserts. but I will heed your warning re messing with rennline transmission bushing. :thumb: :thumb: :grin:
 
:thumb: Probably for the best Phil I am glad you've solved the problem.

I also find it odd that your car with Rennline is ok and mine was shocking.

Fundamentally they are the same car so the vibration should be similar with the same set up. It makes me wonder if there is a connection to how they are fitted or the relationship between the engine and transmission mounts plastics.

I am thinking of getting my transmission mount replaced with standard to see if it makes a difference but would love somebody to explain why its nosiest at the same revs every time.
 
Nimrod said:
:thumb: Probably for the best Phil I am glad you've solved the problem.

I also find it odd that your car with Rennline is ok and mine was shocking.

Fundamentally they are the same car so the vibration should be similar with the same set up. It makes me wonder if there is a connection to how they are fitted or the relationship between the engine and transmission mounts plastics.

I am thinking of getting my transmission mount replaced with standard to see if it makes a difference but would love somebody to explain why its nosiest at the same revs every time.

one of the first things I did when looking for the vibration was head to the engine mounts , we removed the rennlines and found three things

1/ due to the hole adjustment the engine was sitting 3mm over to one side
unsure if that would affect things but corrected it anyway
2/ the square bolt on the mount was not located correctly in the square engine cut out and was sitting on one edge. this was also corrected .on the rennline the square bolt turns freely which the stock ones don't and the tech had not realised it this was on one side
3/ the other side the square bolt had unwould by 15mm down the spline again the tech was only used to fitting stock ones which wouldnt do that so he hadnt spotted it . when we address all those things I have to say some of the harshness disappeared but the vibration was still there so we carried on looking until we found the issue with the transmission mount inserts.

So whether any of those things had also happened on yours might explain the harshness . just a thought mate :thumb: also I am running yellow on yellow bushing which is the softest what bushing were you on :thumb: :thumb:
 
I was using red/yellow in the engine mounts and like you also suspect that they weren't fitted quite square ,

I intend to recheck the new RSS ones when I have time to ensure they are correctly aligned as I suspect this makes a huge difference to the resonance if not correct.

Thanks for the tips Phil :thumb:
 
Nimrod said:
I was using red/yellow in the engine mounts and like you also suspect that they weren't fitted quite square ,

I intend to recheck the new RSS ones when I have time to ensure they are correctly aligned as I suspect this makes a huge difference to the resonance if not correct.

Thanks for the tips Phil :thumb:

Maybe the combination of the yellow (softest) and red (hardest) gives a combined compliance nearer the hardest combination which is probably only really suitable for track/race use.

Phil, I think your problem was related to resonance, something possibly being disturbed during the engine drop and being amplified by the normal vibration, maybe something that was put back tighter or looser than before! Annoying though!
 
DucatiRob said:
Nimrod said:
I was using red/yellow in the engine mounts and like you also suspect that they weren't fitted quite square ,

I intend to recheck the new RSS ones when I have time to ensure they are correctly aligned as I suspect this makes a huge difference to the resonance if not correct.

Thanks for the tips Phil :thumb:

Maybe the combination of the yellow (softest) and red (hardest) gives a combined compliance nearer the hardest combination which is probably only really suitable for track/race use.

Phil, I think your problem was related to resonance, something possibly being disturbed during the engine drop and being amplified by the normal vibration, maybe something that was put back tighter or looser than before! Annoying though!

Rob it was starting to bug me that we couldnt get to the bottom of it , chuffed now its sorted car feels great again :thumb: :thumb:
 
Nimrod said:
I was using red/yellow in the engine mounts and like you also suspect that they weren't fitted quite square ,

I intend to recheck the new RSS ones when I have time to ensure they are correctly aligned as I suspect this makes a huge difference to the resonance if not correct.

Thanks for the tips Phil :thumb:

If you were running half red which are the hardest ones I am not surprised they felt harsher than the RSS the yellow on yellow is supposed to be the equivalent of RSS so yellow blue might have been a compromise as that's what carreramonkey is running and he likes it :thumb:
but for the sake of 45 mins work having a double check of your RSS to be 100% they are seated correctly and that the engine is sitting central. :thumb: :thumb: :thumb:
 

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