Recently I took my car to the track for the first time. Had a great time and learned a lot about the car and its limits. One thing I realized is I do NOT need more power just yet. 280whp is more than sufficient at this time. What I DO want is better feel and road feedback.

I noticed that there seems to be a fair amount of slop in the drivetrain. Basically, the difference from being ON the throttle and OFF and the time gap between when you feel the car pulling and then being slowed by the engine.

I've read that it could be a variety of things from a worn diff, diff bushings, engine motor mounts, PPF, etc. But in my specific case, my car only has about 39k miles on it. I also have solid diff bushings that Rotary Performance installed about 5 months/5k miles ago.

Any ideas?

 

PPF crack usually feel in the shiftknob (**** bounces) i would guess its diff bushings

Had I actually read your whole thing I might have said different. Have someone rev your engine and see if it moves.

 

My first guess would have been the diff bushings but you said you replaced them...

Let's get more info from you before making wild guesses...

What suspension mods do you have?

What engine mods do you have?

 

Suspension is Tein Flex coil overs. I think they are about 5 years/6k miles old from what the previous owner said. New pillow ***** in the rear as of 5 months ago and I have the solid toe links and solid diff bushings from Rotary Performance.

Engine upgrades are minimal but include stock mount IC, 3" SS downpipe, 3"midpipe with high flow cat, intakes, Apexi PFC tuned to 12psi. Car made 280whp at rotary performance when Chris tuned it in early December.

Someone above asked if the shift **** moves when letting off the throttle. It does indeed move a little. Probably half an inch maybe if memory serves me right?

 

Install our transmission crossmember it will eliminate the slop in the trans without adding any vibration. The entire car will feel more responsive. Transmission Crossmember

 

Interesting. I've not seen this.

One question though. Does mounting the transmission in a more ridged manner have any downsides or ill side effects? I know the PPF is supposed to flex a bit.

 

Before adding extra support, verify the PPF, engine mounts etc are all good. Otherwise you are just bandaiding it

 

rotary performance knows their stuff. I'd probably have them look at it. Trying to diagnose stuff over the internet isn't always helpful...



1/2" movement at the shift **** isn't much. How are your engine mounts? Does the engine shake much at idle or while revving?


Can you elaborate upon this statement?

Basically, the difference from being ON the throttle and OFF and the time gap between when you feel the car pulling and then being slowed by the engine.

Are you noticing an issue with throttle response?

 

On some cars, the amount of backlash you feel can be a sign of the diff being worn- the LSD center as well as the ring & pinion may want attention. That caused some significant drivetrain lash on my manual R1, and we chose to leave it alone because the car is less than A1 condition..

About 12 months later, the diff side seals (oil control seals) gave out, which ended up with the underbody sprayed with diff oil :p

Just a suggestion. For track work, and without increasing power, you can get some nice gains by swapping to a good ratio while you're in there... :p

 

Not a track guy but wondering how a lightened FW might factor in to this.... if at all.

 

There is no downside, we have people all over the world running this crossmember with nothing but positive feedback. Here is a review thread https://www.rx7club.com/3rd-generati...eview-1042141/

The PPF is not supposed to flex (or move) that is the problem with the design.

Install our diff brace at the same time and the complete drivetrain will be supported.

 

Just skated out of town till tomorrow but I'll check engine movement tomorrow night.

To elaborate on the previous statement...what I mean is that if I'm on the throttle and I let off I can feel the engine seems to respond/slow immediately but it takes a bit for the rest of the car to get that message. Almost like the eccentric shaft slows and then between there and the rear wheels there's something like a quarter turn of the drivetrain where there's no direct connect.

My explanation is shitty but hopefully that makes sense.

I forgot to mention that Chris already replaced the diff seals. He said the same thing, while he was under there doing the diff bushings it made sense just to do them then so I had him replace the seals.

Mine is stock. Do you mean adding one?

 

The FD is a pretty herky jerky type car from the factory and was one of the complaints when it was 1st released. It's a car that takes some finesse to drive smoothly. The solid rear diff bushings will add to the feeling of herk and jerk when on and off power because they don't absorb any shock. I suspect there's nothing wrong with your car. If you want a nice smooth FD use only stock bushings, motor mounts etc.....

1/2 inch movement is normal for the shifter. Here's what a shifter looks like when the PPF is broken (mine was almost broken in 1/2 at the time of the vid)
Vid won't work here so if interested just search the title in you tube. If you have a broken PPF you will know it, it's not a suttle thing, the shifter was moving a good 3 inches in my car along with very harsh connection between on power and off power.

When OEM bushings are bad the fluid will literally leak out so you can look for that. It's just a clear type fluid but you will be able to see it. If the motor mounts are bad the engine will move when you rev it.

 

Great! finally a video that shows how much a shifter moves when the PPF is bad!

 

Buy the banzai brace and replace your shifter bushing. The banzai brace is one of the best mods I've ever installed on a FD, and there aren't many parts I haven't tried at this point.

 

Yes! And thanks Flynn! Mine CERTAINLY doesn't move nearly that much. I might consider the Bonzai Brace very soon!

Thanks for the help guys!

 

Adding some closure to this thread....my drivers side motor mount was toast. Pretty much broken in half. Apparently, the drivers side mount is different than the passenger side mount and they tend to fail much much sooner. I replaced it with the OEM mount that Mazda made after they got smart and made them the same. The car has never felt better!

 

Love when folks follow up their threads with the fix

 

+1

 

Drivers mount was originally aluminum, and was prone to failure. They updated it later with a steel mount (like the passenger side mount). The drivers mount was likely made of aluminum to save weight.

 

Yep, that's exactly right (to my knowledge). And you'd be surprised how much difference a new motor mount makes!