cricha5

I have had this car for a few months now. The previous owner put a new clutch on right before he sold it. It was bucking when starting out from a stop in first, but I thought that would go away as the clutch broke in. It hasn't gone away. In first gear, from a stop, when releasing the clutch and giving a normal amount of power, the car quickly bucks forwards and back. If I give it a lot of power, this does not happen. It does not happen when engaging the clutch at any speed, only when stopped.

I suspect the previous owner noticed the problem and tried to fix it with the new clutch. When it didn't fix it, I suspect he told me it was because of the new clutch.

I realigned the power plant frame. It needed this, but it did not help the problem.

I think most people will say that the flywheel is warped. Is there any way to test this without removing the flywheel?

It could also be the engine or differential mounts. My stick shift does move around a little on bumps. About 3-7mm I would say. Since I didn't buy the car new, I dont know if that is normal. It moves a lot more when it is bucking. I visually inspected the engine mounts and they seem fine. Is there a better way to test them? Since the ppf connects the engine and diff, I figure it could also be the differential mount. Is there any good way to check that mount?

Thanks

1.3_LittersOfFurry

iTrader: (4)

I have the same issue, it only happens sometimes for me. I've already replaced both engine mounts, which helped a lot, but the ruff starts from 1st are still there. I would love to replace the differential mounts but I can't find a place that sells them, and I am un sure on how to change them.
As far as my clutch, it grabs great, but I have no clue when it was changed last.

cricha5

Diff mount: http://onlinemazdaparts.com/partloca...layCatalogid=0

It looks like a giant pain to replace.

cricha5

The ppf was misaligned and I aligned it. No change. I don't really see how a misaligned ppf could cause the problem anyway, but I realigned it just in case.

Furry, how did the new engine mounts help? Did they lessen the bucking or reduce how often it occured or what?

1.3_LittersOfFurry

iTrader: (4)

Oh that looks like fun....



I'll have to look into this.


Both, it still happens but not nearly as often, and when it does happen its a "softer" feeling. (sorry best I can explain). I also find it happens more often with the a/c on.... just not sure why.... Infact 90% of the time I would just leave the a/c off to help avoid the situation. Once I got a BHR ignition system (for other reasons) the problem seem to be even less noticeable cause now I just leave the a/c on and it barely happens... not sure how that happened either but I won't complain.

But its still happens and I would like it to stop... I still get a small hesitation in 3rd gear under 3k rpms, which makes me think it could be the differential mounts. My car has 97k on it, so anything is possible at this point.

cricha5

Can anybody chime in on the "normal" amount of movement the stick shift should have on bumps, etc.

Furry, if the new mounts made the chatter better but not gone, then there is still a problem that both of us have. Has your chatter been there since you got the car or did it develop over time? Also, the power plant frame realignment is fairly easy and free. I highly recommend it. I would strongly advise getting yourselft a good cheater bar for the job.

1.3_LittersOfFurry

iTrader: (4)

It's been there since I got the car in January, That was about 8,000 miles ago.

I searched for adjusting the PPF, and I found a post where Charles explained how to do it, but since I never really got a good look at the PPF it left me a little confused. When I get off work today I'll slide under there with the instructions on my phone and see if it makes sense then.

-Edit-

Let me also add, I suspect I have a failing clutch pedal, not sure if that contributes to problem or not (or if its even a problem at all). When I first got the car it seemed the pedal was adjusted wrong and was not disengaging the clutch fully when pressing the pedal. I readjusted it myself to a slightly higher point. It always felt like the clutch would grab at different heights of pedal travel, I ignored it thinking it was all in my head sense it had been about 6-7 years since I drove a stick. But it still feels like sometimes the clutch is not engaging at the right point, sometimes lower, sometimes higher, sometimes the clutch slips very easily and I get a very nice smooth take off, other times it grabs like a bitch and I jerk when taking off.

eretromicin

what do you mean by a "normal amount of power" in terms of rpms? from what it looks like, you may be slightly overestimating the low-end power of these cars... keep in mind that there's practically no torque below 2k rpms, so releasing clutch below that point a little too fast will cause exactly what you've described...driving rotaries is a lot like riding rice rockets, they do not move unless you give 'em some beans...

as for the "normal" stick shift movement over bumps, 3-7mm sounds right... after all, the transmission is not really bolted to the chassis, so a fair amount of movement is to be expected...

you can reduce that "all-over-the-place" clutch engagement buy changing the clutch line to a steel braided one... also, make sure there's no air in the clutch line

cricha5

A normal amount of power being enough power to accelerate in a reasonable manner. I will try and look at the rpms i drop the clutch from. I am, however, quite confident that I am giving the car enough power. I've been driving underpowered manual cars for a long time. Also, the kind of bucking resulting from improper clutch/power operation has a much lower frequency than what I'm talking about. I think I'm talking about clutch chatter, but never having experienced it before, I am just guessing.

1.3_LittersOfFurry

iTrader: (4)

The clutch line is new, but rubber/oem. I also flushed and bled all the lines with a mighty vac kit when I bought it.

I'm starting to think it's the pedal itself, I know it's a weak point and when I was looking at it yesterday I noticed it has changed to a higher resting position than I had originally set it at (it's now higher than the brake pedal, last time I adjusted it, it was even with the brake pedal). The clutch pedal also moves left and right a lot and squeaks.

This is also my 4th rotary powered car so I'm aware of the no low end power. (not sure who that comment was directed at, so just saying...)

eretromicin

@ Cricha5 Clutch chatter could be a warped flywheel, or simply a bad clutch... your only option here is to remove the transmission and inspect both parts...although, a warped clutch would be a pain to spot. much easier with a worn out clutch. My car did something similar when i bough it, but it also had a bad transmission. When i took the old transmission off, i found that the old clutch was completely gone. It still had a lot of friction surface, but the four springs inside it were bad. (overcompressed, if that's a word)... but either way, IMO, those parts need to be looked at...

@1.3 litters of fury, i found that quite a few rx8's have problems with the master clutch cylinder... the plunger does not always return all the way because the actual rubber part of it gets stuck in the cylinder. try spraying some wd40 inside it while completely depressing the clutch pedal. fixes mine when i have problems with that... Mazda has some specific grease it uses to lubricate the clutch master and slave cylinders, but from what it seems, that lubricant does not hold up very well against DOT3/4 brake fluids... lithium-based lubricant might be a better choice, but i'm not certain on that as i have no idea what kind of resin compound they use on that plunger... as for the assembly, just use some synthetic bearing grease... mazda told me that those pedals work just fine up until they completely break, so slight movement to one side or the other is not a big deal. however, you could check if you can tighten up any bolts/nuts on the assembly as sometimes those just get undone from the usual tear and ware.

jasonrxeight

its funny my clutch kinda shakes ONLY when I am moving slowly in 1st gear and try to slip it.
no shaking when starting from standing still.
I think it has something to do with the design.

eretromicin

Actually, you gave the perfect description of what my car did before I trew that old clutch out...you may be right, but it hasn't done that even once since I replaced that clutch (a year ago)

cricha5

Thanks for the advice eretromicin. I think I agree with you. I hoped against hope to find a simpler solution, but I think I'm going to have to pull the transmission. I think I'll wait till the temps get bellow 90 first. I hear we might be getting a hurricane, maybe that will help. I'll grab a used flywheel and a new clutch pack that is returnable in case I end up not needing it. I'll make a new post to get advice on how to get the car high enough to do this job comfortably.

1.3_LittersOfFurry

iTrader: (4)

I'll also try out your suggestions once our storm passes. Thanks.