Author Topic: Drivetrain noises  (Read 1757 times)

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Offline FCwidman

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Drivetrain noises
« on: May 11, 2017, 03:53:53 PM »
Hey guy, didn't want to clutter the message bored with this question but
Every once and a while when I shift there's a clunk, kinda like something is shifting around under the car. And also a vibration at 2-3k with mild load but only in 2 and 3rd. I noticed it after I had put a solid front diff mount and new sub frame dog mounts, I drove it to Florida and back a day after I had done these and then the noise started.
First obvious thing I noticed was my trans cross member bolts backing out, those are torqued down and lock tighted now. The sub frame is still torqued down, only thing I can see that's potentially wrong is my driveshaft turns about an 1/8 to 1/4 turn with e-brake on, I'm hoping my ring and pinion haven't shifted.
So basically wondering if any one had any insight before I decided to tear my rear end apart .

Offline ITSWILL

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Re: Drivetrain noises
« Reply #1 on: May 14, 2017, 08:51:51 PM »
Could the solid mount be broken?  I have seen the break in the past. Did you check your axles too?

Also, regarding a the front diff mount, I have put pinion snubbers in all my rx7s and friends rx7s whenever the diff has been out, with stock mounts and this combo is stiff and has worked flawlessly.
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Offline FCwidman

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Re: Drivetrain noises
« Reply #2 on: May 16, 2017, 06:50:37 PM »
I checked the solid mount as best I could, I couldnt get the front of the diff to budge by pushing up on it and couldnt see any cracks. my trans has been leaking fluid more and more rapidly lately and im leaning more towards that now, so pulling the engine and trans in the next few days to replace the front seal, rear main, and oil pan gasket. also give the front u-joints a better look. A rear end flush might be in the works here soon too, maybe ill find some killer wear marks on the ring. stay tuned

Offline ~Groll69~

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Re: Drivetrain noises
« Reply #3 on: May 17, 2017, 08:35:27 AM »
Let us know what you find.  Hopefully, it's just the seals that need to be changed and that you were just low on some fluid to cause the noises, but no additional damage.
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Offline FCwidman

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Re: Drivetrain noises
« Reply #4 on: June 01, 2017, 10:12:42 PM »
quick update on  this, engine and trans was pulled and new rear main seal, trans front seal, oil pan gasket, and oil filter stand o-rings were all replaced in an attempt to keep my fluids inside and not on my driveway..

Haven't noticed any noticable leaks but it's also been sitting in stains from the engine pull, however now the car will not go into gear while it is running. It shifts perfectly when it is off, the clutch is not disengaging at all. Slave was bled and did nothing, new slave was put on and same problem. the pedal has no pressure at all and does not build any, although sometimes it feels like its getting better during bleeding but quickly goes back to nothing. Will also stick to the floor on occasion. fork does move a good inch or so

Trans just got taken back out tonight to check if the throw out was put on backwards, it appears to be on correctly unless i've been putting them on wrong my whole life. didn't get a chance to look at the pressure plate, but thats next on my list of things I might have rushed through too fast and somehow installed wrong. After that I'm thinking maybe a bent fork(looks perfectly fine), clutch master cylinder is bad, or I just need to bleed the slave for another 3 hours.
Also drive shaft fron u-joints were cracked and popping pretty good, driveshaft seems to be toast for now. Recieved a replacement from Murz, thanks again! maybe that was the source of vibration.

I'm at a loss on this and was putting all my eggs in the throw out being backwards basket, I need the car on the road in the next couple days to get it ready for grid life, I'll try a clutch engagement dance at this point.

Offline toplessFC3Sman

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Re: Drivetrain noises
« Reply #5 on: June 02, 2017, 05:37:49 AM »
Do you have any pictures of the various bits and pieces that you could post up? Sometimes pretty small differences in thickness or tolerance can have a big impact.

How did the bleeding go? Were you able to get a constant stream of fluid with no bubbles? If not, then I'd definitely look into the clutch master cyl. If you were, and you said that you can see the clutch slave cyl moving the fork when you press the clutch, then that points towards some other fault. How much does the slave cyl move? At least an inch or so?  If so, I'd tend to focus more on the clutch, pressure plate, clutch fork, or some other fault than on the hydraulics in this case. The fact that you said its moving but that there is basically no resistance makes me think that something in the stack-up between the clutch slave cyl and the pressure plate isn't correct. Bent clutch fork, incorrect throw-out bearing like you had said, or bad pressure plate seem like the likely contenders, although I guess its possible that the clutch slave itself is an incorrect part

Post up a picture of the trans input shaft, focusing on the smooth area that slides inside the pilot bearing in the end of the e-shaft, and on the splines that the clutch rides on.

Try pushing down all of the pressure plate teeth to make sure that you can see some movement of the friction surface inside the pressure plate. I'd look at each one individually, and then if you have a vice or hefty clamp, try to rig up something that would allow you to press them all to make sure the friction surface moves in the direction that would be away from the flywheel when the teeth are pressed towards the flywheel.

Inspect the clutch carefully, looking for scrapes, indentations, or other signs of damage. Its possible for something to have broken and jammed underneath the pressure plate, but it should have left a mark. Does the clutch slide freely along the splines of the trans input shaft? The clutch wasn't installed backwards, was it?

Does the pilot bearing in the hole in the end of the e-shaft look ok?

Offline FCwidman

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Re: Drivetrain noises
« Reply #6 on: June 02, 2017, 08:34:58 AM »
I will get some pictures in a little bit. bleeding went as well as it should, i bled it a good 10 more times after no more bubbles had leaked out just to be sure. The fork moves about an inch or maybe more, and doesnt appear to be bent but I'll take it off to get a better look.

At first glance, nothing seemed wrong with the transmission side. No marks on the bell housing, input shaft splines all looked good, throwout moves freely on the shaft and spins nicely. Also no gear oil in the bell housing which is a plus!

Yesterday was a long day at work and I was falling asleep under the car and didn't look at the pressure plate. I've got the next couple days off so after I eat something I'm going back out there and will take some pictures of the trans and clutch assembly. I'll post them up in a few hours

Offline FCwidman

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Re: Drivetrain noises
« Reply #7 on: June 02, 2017, 10:24:49 AM »
Having trouble getting pics to load on my computer, any way to do it through an iPhone?


Well apparently I'm my 4 years in auto engineering school I didn't learn how to read because I put the T/M side of the clutch disk towards the engine. Gonna go over everything just to be sure but I'm 95% sure that's gonna cause no interaction between pressure plate and clutch
No odd wear marks or anything broken or bent so far

Offline toplessFC3Sman

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Re: Drivetrain noises
« Reply #8 on: June 02, 2017, 01:02:25 PM »
Thats a good sign -  if the clutch disk friction surface is not centered on the splined hub when viewed from the side (and usually they aren't, for packaging the sprung clutch hub, spline etc up against the relatively flat flywheel), it could be constantly pressed into either the flywheel or pressure plate friction surface, so even if the clutch hydraulics, fork, throw-out bearing & pressure plate were working perfectly, the engine would still spin the trans.

While you're in there, it doesn't hurt to look over everything, but its promising that you found something.

Offline FCwidman

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Re: Drivetrain noises
« Reply #9 on: June 02, 2017, 02:40:34 PM »
Trans isn't back in, clutch works great! Just puttin the exhaust back on and off for a drive I go. Might make it to Woodward tonight if all goes well.

Hopefully this fixed all my vibration and noise issues that were the original issues I was concerned with

Offline toplessFC3Sman

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Re: Drivetrain noises
« Reply #10 on: June 03, 2017, 06:28:25 PM »
So, drivetrain vibrations taken care of too? Glad the clutch issue ended up being something relatively simple (even if its a bit of work to get back to it)

Offline FCwidman

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Re: Drivetrain noises
« Reply #11 on: June 05, 2017, 05:56:42 AM »
 all the vibrations have not come back, still dripping small amounts of oil from somewhere though.

Offline murz

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Re: Drivetrain noises
« Reply #12 on: June 05, 2017, 06:54:24 AM »
Glad it's fixed and the new driveshaft works too. The oil pan can be extremely difficult to seal I've heard.
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Offline FCwidman

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Re: Drivetrain noises
« Reply #13 on: June 11, 2017, 02:50:34 PM »
Drove the car a few hundred miles over the weekend to South Haven and back. drives nice and smooth down the road. Still seems to be a clunk everyonce in a while when I let off the clutch. No where near as loud or consistent as before, no more vibrating and shaking at low load, and the drivetrain is nice and quite. The search will continue for the clunk.

Some small leaks here and there, havnt been home enough to determine if its engine or trans leaking. oil on the dipstick hasnt moved, but it never really seemed to move before either.. Wish there was an easier way to check the trans, being stupid low makes jacking it up a task.

Offline fidelity101

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Re: Drivetrain noises
« Reply #14 on: June 28, 2017, 08:58:25 AM »
With the solid or more solid rear end bushing for the subframe/diff it tends to bit more connected aka solid so I get a bit more abrasiveness feeling when adding/removing load. Like there is less slack it just has a more harder linked feel. If you want to get rid of that you may be going back to rubber mounts.