Powerslave

My car rolls in 1st gear (when the car is off), this seems a bit odd to me, also it jerks around when it decelerates. Its always done this since ive had the car, do I have a problem somewhere in my Diff or Box? its got an Aussie Series 3 Diff which is probly the same as the 13b diff from the GSLSE 1st gen in the USA.

speckamp

bad clutch maybe? I dunno if i'd suspect a diff, unless it was really hosed, and the box would have to be pretty stuffed to roll like that.

arrexeven

My 84 GSL's doing the same things. Realizing that the rotary doesn't have the compression of a piston engine, I've come to accept that simply putting it in gear won't hold it on a hill.

That herky-jerky deceleration has me puzzled too, though it only happens when revs get down, or when coasting in low revs in 4th or 5th.

I'll be interested to see how this thread develops.

jeremyriv

Puzzling...

Mine does the same, so I always thought it was a poor clutch... But, mine DOES need replacing. Also, for me it could be this: I have a leak in my clutch line somewhere where it doesn't drip on the ground. (prolly in the tranny) so maybe for me there is not enough pressure on the plate because there isn't enough pressure in system?

Keep posting any info guys!

Montrealer

If there was not enough pressure in your hydraulic system, it would make no difference, the grabbing capacity of your pressure plate could be a cause...


But I also have come to accept that this problem comes from the low compression of the rotors, the reason for this assumption is because when the car starts to slide down my drivway, the car does not go down smothly, as if the engine compresses the air in the chamber and then uncompresses it and so on...

jeremyriv

I agree with you!

Not to get off the original subject, how much will it cost me to replace a section of the clutch line?

Josepi

for prices, check dealer, or www.mazdatrix.com

I should get a discount for all my shameless plugs!

jimmyv13

The surging while decelerating is caused by a bad shutter valve. I don't know how much work would be involved in changing one since mine was done while the enigne was being ported.
The "rolling in first gear" sounds like poor compression to me. Try the ATF treatment for at least 24 hrs....and roll the car backwards while in 5th gear about 5 feet every 3 or 4 hours. Push the car outside to start it. It will smoke severely, not to worry though. Wait til the car reaches operating temp and go out and run it to redline until the smoking stops, usually 5-10 times. Change your oil and spark plugs afterwards. That should bring up your compression. I just did mine last weekend, it feels like a new car. I can't believe the improvement.

Serzy

My car also surges while decellerating when the revs start to drop... its very annoying... but I have removed most of my emissions quipment... so is there anything else that can fix this, or should i just live with it?

jimmyv13

Change the shutter valve or disable it.

jimmyv13

click here to find how to disable the shutter valve

davo22

try placing the car in reverse to lock the drivetrain. Works for me. lates

peejay

Reverse won't work either... one time i pushed my car forwards for about a dozen feet before I realized I left the car in Reverse. I was wondering what was making those funny whooosh-whooosh noises under the hood!

Rotaries have almost NO compression at very low engine speeds, and they have no valvetrain either. You need a big wrench on the camshaft bolt just to turn the CAMSHAFT on an OHC engine. I can easily rotate my 12A with one FINGER by pushing on the alternator fan's fins. (In fact, I do this when marking the e-shaft pulley when checking my timing!)

Leave the car in Neutral and use the handbrake to hold the car still...

Max7

Thats why you see the rotary guys at the track with wheel blocks, so when when they come off track they can park thier car and keep it from rolling since they can't use the ebrake. and they know the engine in gear can roll easy.

Jeff20B

iTrader: (13)

Yep. I also spin my engine by hand (fingers on the alt blades). to line it up to do distributor stuff and what not. It shows how little friction there is inside a rotary engine

That surging could also be lugging. Lugging is caused by the RPM being too low for the speed at which you are traveling. Just shift into the next lower gear on deceleration.

My bro's GSL-SE had a broken tranny mount (rubber seperated from the metal). After it was replaced, it felt a lot tighter, but it still wiggled. I thing his front motor mounts were oil soaked and the rubber was basicaly dead (well, the one near the oil cooler lines anyway).

My friend's rotary truck has no Ebrake due to running ove a dead deer (lol). Poor truck (the deer was already dead! Where's Tom Green when you need him?)

arrexeven

Jimmy, my shutter valve has been disabled for over 2 yrs (whole different set of problems) but my herky jerky shuffle started about 6 weeks ago. Any other thoughts?

zyounker

I believe the jerking is cause by broken tranny mounts...


-Zach

jimmyv13

Check your motor mounts and the tranny mount. When does the surging occur, acceleration, or decceleration?

arexsevin

My sevin used to jerk around when decelerating until i took a close listen to the engine at idle...... i found a small vacuum leak...once i fixed it...... it cured poor idle and the jerking when decelerating

S2-13BT

I get the jerking when decelerating as well. As the revs drop to around 1500rpm the jerking starts. It's not voilent it's just annoying and definately noticeable. It's puzzled me for awhile, and I always assumed it was the diff or gearbox, both of which are noisy, but AFAIK still in reasonable condition.

I might check out the tranny mounts and see how they are.

peejay

The rolling is because rotaries have next to no compression when they are not spinning. You should be able to turn your engine with finger pressure. (This is also why you NEED a strong battery, starter, and battery cables - that engine has to spin up to start easily!)

The bucking is because it's a rotary. All rotaries will buck like that at sufficiently high manifold vacuum. With a stock port, you can only get enough vacuum to buck when you're coasting in gear with the throttle closed. Additional overlap makes the bucking occur at lower and lower amounts of manifold vacuum until finally it occurs in the range where the engine is normally at during an idle. (brap brap brap...)

The shutter valve is there to combat the bucking, by shutting off half the carb and injecting a ton of air into the intake manifold, which reduces vacuum without increasing power. A stock pre-81 car will buck. A stock 81-up car will not buck, assuming all is working properly. (Mine doesn't buck, and everything is there and functional)

edit: JEEZ-US!!!! I didn't realize that this was yet another Back From The Dead post. What is with people suddenly replying to a metric shitload of year old posts? It's not just here, it's in the other sections as well.

Stripgear

iTrader: (2)

It's the infamous 3:3 misfire. See attached.

peejay

Wow...



I've calculated this misfire rate before, by calculating the frequency of brapping at a 1500rpm idle and then working backwards to see how many cycles "hit" and how many "miss".

You can use this to figure how fast an engine is idling, just by sound... it sounds really weird at 600rpm

S2-13BT

Mine does the bucking, and it's a S5 TII engine. Your right though, that it only does it when coasting, off the throttle with the revs around 1500 or less.

peejay

is your tps adjusted right or if you have a standalone do you have a coasting fuel cut enabled?