transmission Mount/motor mount/crank pulley ?'s

[Kansei240sx]

RB20DET transmissionRB25DET S1Fidanza RB20 9.5 lb flywheel300ZX Z31 DXD Pressure plate and Kevlar Disc clutchZ31 T/O Bearing with the RB20DET ARM and Bearing mount

about 5-6000 miles on parts listed above minus the transmission and motor.

The other night i went for a bit of fun in the rain, aka drifting and the car was fine.

It drove home with no vibrations etc...

Well i start it up the next night, and the transmission is shaking, and making a knocking sound IN NEUTRAL, and goes away as i press the clutch a little. When the engine idled for a little while, then it went away after the car warmed up. As i depressed the clutch it barely came back and then went away as i started moving.

I took it for a drive and no serious vibrations or gear clunking occured.

I took it up to work and drained the fluid, it was a tad dark. I refilled it, and fired it up, and the knocking or vibrations seemed to be much worse this tmie, and when i'd apply the throttle lightly 15% or so up to about 3000-4000 rpm blips, the entire car/engine would shake on the lift and it felt or sounded like, something in a specific rotating assembly was unbalanced, much like the vibration felt from an unbalanced tire.

I did notice however, that the transmission mount was sagging and causing the two bolts that hold it to the transmission, hitting my Tophat transmission X-member. So i know that the mount is bad, my question is, is the SR20/RB20 transmission mount(rubber insulator) compatible? Im thinking of picking up one of those URAS Polyurethane transmission mounts because the factory ones end up just taking a **** on me.

I ended up yanking the transmission out, with the engine still in the other night, IT IS POSSIBLE, BUT ITS A WHORE POINT 5. I made some more room in the transmission tunnel tonight, so it will be a bit easier. I noticed when i yanked out the pressure plate bolts that 1 out of 9 were just a bit more loose than the others, so that may have been part of the problem.

Im going to see if the crank pulley bolt is torqued down, if its not i will tighten it down and see if that cures anything. Also, i got the tophat racing mounts, and those are also sagging after over a 2 year period of constant track abuse and stiff suspension on oklahoma roads. Has anyone here with tophat mounts replaced those with something else and had good luck? Solid aluminum, or even urethane.

The car is more or less, slowly being converted to a full track car over the time i have it, so in the long run im wanting something stiff to hold up, but not to stiff to where it starts tweaking the frame/ alignment values.

Also, i noticed there was a chip on the crank pully that i didnt think anything about from awhile ago. It hasnt made the car feel any different, so i doubt thats the problem.

Does anyone know there is a cross referenced part for the crankshaft pulley?My friend told me he got a crank pulley off a car here in the salvage yard, but doesnt remember what it came off of, he just noticed it was identicle to the one he already had.

I think thats about all of my questions, but if anyone could throw some advise my way i'd appreciated it.

[Darius]

I don't know about your crank issue, but I am having the same issue with the Tophat transmission mount. I will try to get a picture up because it is sagging about 1/4" and bounces around when I try to do a burnout or launch. I'm hoping to design a stronger one and have it fabricated this winter. If it is good enough and easy enough to make, maybe I can sell them to all the Tophat mount owners for cheap.

And where can one buy polyurethane in bulk? It would be nice to be able to make exhaust hangers and transmission isolators.

[Kansei240sx]

I did see a thread on this forum in the tech articles where AZ hitman made some mounts out of flexane and used dixie cups.

URAS makes a solid urthane transmission mount that looks like so...

As far as i know, i have been able to interchange my RB20/RB25 engine mount with my Tophat transmission x-member.

And this looks near identical to the worn as hell and spongy rubber ones i have now. I took out the factory bolts that hold the mount to the transmission, put the bolt going in from the bottom, and took a large M10 nut and ground off one side with the grind stone to make it centered and not spin when tightening and it seems to not knock or anything of the sort while driving.

I got the transmission back in and all seems just as well. It will tide me over until i find a solution for it.

I think i should just make like a flexane brick or something and then put some brass or SS collars in for the bolts to mount too and bam, self made stiff *** transmission mount.

[THP]

Hey guys, Give me a call and I will take care of all the mount problems at no cost. I would also like to source poly isolators.Thanks, MikeTop Hat Performance

[Darius]

I think what I'm going to do first is make the stock RB transmission mount into a rigid poly mount. Just going to pour it full of Flexane 94 to take the play out of the stock rubber isolator. Hopefully, that will help keep the metal mount from fatiguing as much. I also pounded that mount straight again.

THP are you still having these mounts made? There are quite a few points I would like to express to improve the product at minimal cost and effort. Not just the isolators.