heli

I just finished installing a rebuilt engine because mine had been dumping oil into the intake and had bad compression. I installed new BHR motor mounts and a new exedy stage 1 clutch. When I start the car when its cold and its idling around 1500 rpm it has a fairly nasty rattle/vibration. As soon as the idle drops to normal its fine. When I start to let the clutch out in first gear as soon as it hits the 1500 rpm mark it starts to rattle and shake again until the rpms are above 1500. I was wondering if it is just a characteristic of the BHR mounts or a new clutch. I'm worried I may have damaged something when I installed the engine. Any help or ideas would be greatly appreciated.

-Matt

heli

I finally got a chance to undo the mounts and lift the engine up and sure enough they were preloaded. The left hand mount was the problem. Set it back down and torqued it up and the excessive vibration went away. Thanks again for the help Charles.

heli

After driving the car for a few days the vibration is now back. It is worse when the car is cold and gets a little better when everything is nice and hot. Anybody have any other ideas. I'm pretty sure its not the motor mounts.

Rx8dude2016

I just got one so no promises I'm right but ive read that rattling can be from a cracked engine mount, mine has been rattling and I had to take it in because my idle was messed up. Ive also had times when my air conditioning makes the car rattle.

heli

So I have about 650ish miles on my new rebuilt engine and it still has a decent vibration in the 1350 to 1450 rpm range. I've check the engine mounts and the part of the frame where they bolt up, the transmission mounts and the exhaust (but I strongly doubt that that would be the problem). The car has new engine mounts, new coils plugs and wires, new stage 1 clutch throwout bearing and pilot bearing the flywheel was also resurfaced when it was rebuilt. Its not the ac making it shake unless removing the compressor and drive belt would do it. I'm pretty much out of ideas. I can live with it but would rather not. Never did this before the rebuild. Please help.

IWillBuyRX9

Sorry to bring this old thread back... My 8 has pretty much exact same problem like you described here. Car starts to vibrate when hit 1250-1500rpm, vibration goes away at below/above this range of rpm. Would you mind share what the fix was if you have successfully diagnosed the cause? I am wondering if it is caused by a bad clutch component because the vibration still exists even it is in neutral.

heli

I eventually came to the conclusion that it was just high NVH from the BHR engine mounts/heavier duty clutch. It always drove fine and never had any issues. When I blew the second engine (bad rebuild) the clutch was perfectly fine. I'm now on engine 3 and a different clutch and it still rattles just at a different range.

mazdaverx7

iTrader: (6)

IWillBuyRX9, The hydraulic engine mounts absorb a ton of vibration and replacing with poly mounts can introduce vibration that would normally be absorbed with the hydraulic mounts. As heli found out, this is the one drawback of going with a different type of mount or a different durometer of rubber hardness if the mounts were solid.

TeamRX8

iTrader: (25)

Unless you have a supercharger or turbo it’s been repeatedly advised here not to upgrade the clutch. The OE or OE replacement clutch provided by the usual quality brand manufacturers is adequate for even competition/racing with the best possible normally aspirated Renesis engine output

IWillBuyRX9

Unfortunately the vibration does exist even with the stock engine mounts. I did replace the stock engine mount with a set of poly mounts recently and the vibration became worse as expected since poly ones were more rigid. I was not sure if the previous owner did any clutch jobs/replacement but I guess the only option I have now is to do an OE clutch replacement...

CaymanRotary

Never had a problem with Exedy. This car doesn't need anything more than OEM unless adding significant power. It was overbuilt for 230 bhp and could probably handle more power with ease.

potatochobit

heli, why dont you just buy some OEM mounts and see if the problem goes away?

were those new OEM mounts? because most car engine mounts last less than 50,000 miles before starting to deteriorate.
on my RX7 I had a torque brace that helped alot but they dont seem popular with the RX8 aftermarket, of course you still need to find the actual problem

Doblegota

kind regards,

I’m using The Ryan ROtary performance mounts (red ones) and since I installed the new engine it has that vibration between 1300-1700rpm. When cold it vibrates until drops to 1200 and to normal idle. When you change gear and you start reving from 1200rpm it vibrates. But after 1700 nothing more.

I have red in the forum several post relating these vibration when changing the mounts.

my engine has 6000kms with exedy oem clutch and properly aligned with the PP. Shame to life with these circumstance.

by other hand, I want to ask for vibration at very high speed. Above 90mph+.

What happens is that at driving Hard in 5th to the limit starts a vibration and shaking above 90mph and when you let the car cruise and decreasing the velocity it stills the vibration until you continue in 6th gear at 70mph. When cruising disappears. It’s only at such high speed.

¿Tyres? ¿Suspension? ¿Counterweight and light flywheel?...

it was difficult to find in the forum something of these issue.

kind regards in advance.