Hi Guys, I've been trying to figure this problem I've been having for a while but still cant figure it out. Every time i apply moderate throttle while shifting or from a stop, the drivetrain shudders and shakes before catching. So far I have checked and changed the following and still have the problem.

1. New trans (car was having 5th gear grind)
2. Swapped entire rear stock pumpkin to new one with cusco 2way LSD
3. TPS readings are within range
4. New Delrin bushing set including diff bushings (this helped a little since originals were shot, but still having the problem)
5. Checked PPF off the car at least 2-3 times and have not seen any cracks

Not sure what else I can do at this point besides new pillowballs, but I do not see any play in the ones on the car at the moment. I have seen a couple other people with this problem and seems like ppf is the culprit usually, but maybe I have overlooked something? I was thinking about getting a diff brace, but I do not think thats the solution, only a band-aid. This has really taken away from my driving experience, but I'm trying not to give up. Any help would be greatly appreciated!

 

complete mod list please

 

Car is a 93 R1, this should be the full list. Engine was rebuilt right before I bought the car and should still have under 10k miles on the new engine at the moment. Chassis is at 150k

Engine:
Garrett T-67 T04R (T4 "GT35" exhaust housing) VBand .84/.70
Tial 44mm wastegate with dump
Tial BOV
Mild Streetport
Greddy elbow
Rotary Aviation 2mm RA Super Seals
MazdaSpeed Seal Kit
RX-8 Eccentric Shaft
FC Rotors (lower compression)
Competition Oil Pump
Engine Dowel Pinned
Single Turbo Vacuum Line Simplification
Polyurethane Engine mounts

Drivetrain:
ACT Xtreme Duty Clutch
ACT Flywheel
Cusco RS 2 way LSD
Mazdatrix short shifter

Cooling:
Rotary Extreme VMOUNT Intercooler
Koyo Radiator
TII fan switch sensor

Engine Management:
APEXi PowerFC
GReddy Profec B Spec-II Boost Controller & Turbo Timer
Autometer Oil, Water Temp, Fuel pressure, Boost gauge
AEM uego wideband

Piping:
Racing Beat dual tip
Midpipe with RT HF cat
JPRO Downpipe

Brakes & Suspension:
Tein SS
Delrin Bushing set
Racing brake 4 wheel kit with ET700 pads

Fuel and Ignition:
HKS Twin Power Ignition
RC 550cc Primary 1300cc Secondary Injectors
Walbro 255lph Fuel Pump
JPRO Fuel Line
Fuel surgetank cover

 

After installing my light weight fly wheel and clutch I some times get a shake.

Did you recently change that?

 

What clutch disc do you have? If it is a 6 or 4 puck style you will not get easy engagement. If it is one of the organics then it is something else.

You may want to check your driveshaft for u-joint wear. This ususally presents itself as a vibration higher in the rpm range, but stranger things have happened.

Diff braces are not band-aids, that is like saying a strut brace is a band-aid. They serve a very specific purpose, that is to stop the front of the diff from lifting during launches. This eliminates wheel hop. This will not solve your current problem.

 

Thanks for the replies, honestly for the clutch disc, im not sure but I think its the street disc. I should have checked the last time the tranny was off but the thought did not cross my mind. The problem is only initially when throttle is applied, but it does happen consistently. Its kind of hard to explain but when the clutch engages, it does so smoothly, but once throttle is applied the drivetrain will buck and knock usually twice. Is there a proper way to check the u joint? Im thinking just check to make sure theres not any play.

 

I think you guys are probably right about it being the clutch. If I shift aggressively or baby it in, I get less/no drivetrain shake. I also adjusted the clutch pedal height a bit and seems like it helped too.

 

My PPF was cracked at the front (rather than the rear where they typically break) and gave me the same symptoms.

I replaced mine a month ago, and it solved my problem which sounded like your symptoms.

 

hope you get it all figured out Dan, your car is a beauty

 

Does the shifter move when in neutral and you rev the engine?


Does it move when in gear and you get on the throttle and get off the throttle?

 

Also make sure that no part of the engine is touching the frame of the car. Had a car once with weird vibrations at certain times, the Y-pipe was touching the strut tower brace.

With stiff motor mounts and diff mounts, you're gonna get some more vibration and harshness too.

Dale