Rock-tumbler noise comming from M5R2

MikeKanterakis

SCCoA Member
Hey guys, what would explain a "rock-tumbler" style noise coming from the gear box? When I shift into gear, the shifter feels a little sloppy-er.

Then, when I'm in gear, and accelerating nice and easy, the gearbox sounds normal. But, give it a little more gas, or be in 3rd gear when I should be in 2nd gear (for a normal acceleration), I get this grrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr. Let off the gas, and it goes away.

If I were to guess, I would say that those stock blockers are toast.

Reason I say this is because I just found out how to shift with out using the clutch. Just accelerate up to 3000, pull out of gear as you let off the gas, and then hold with gentle pressure into the next gear. Once the proper rpm's are reached, it slides right in. It's amazing how quietly and smoothly it goes right in. Could I have burnt up my blockers with this method of shifting?

Also, assuming that is the problem, how bad is continued driving under these conditions? Transmission threatening, or just an annoying noise?

Thanks. Hope everyone had a great New-Years. :cool:
 
Floating Gears

MikeKanterakis said:
Reason I say this is because I just found out how to shift with out using the clutch. Just accelerate up to 3000, pull out of gear as you let off the gas, and then hold with gentle pressure into the next gear. Once the proper rpm's are reached, it slides right in. It's amazing how quietly and smoothly it goes right in. Could I have burnt up my blockers with this method of shifting?
Actually what you "discovered" is the proper way to shift. It's what semi drivers call "floating the gears". BTW: You can also float the downshift, by slightly letting off the gas, sliding the tranny into neutral, reving the engine about 1000 rpm, letting the rpm drop slowly, slight pressure on the shifter, & the tranny will drop down a gear. There is absolutely NO wear on the tranny when shifting in this manner. That is because the tranny will only shift when the gears are rotating at exactly the same speed. Blockers (syncros) speed up/slown down one gear or the other, to the same speed for gear engagement. Actually syncros are only meant for (1) starting/stopping, (2) People who never learned how to shift properly, (3) Racing.

I float gears in my '89 XR-7 all the time. All the young SC "kids" are amazed that it's possible to shift w/o the clutch.

"Sometimes it's possible for an Old Dog, to teach a Young Pup, an Old Trick"!!!!

68COUGAR
 
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Yeah, it felt pretty natural. Downshifting seems a little harder to do b/c I have to work to gas pedal to match the rpm's for the lower gear. But for normal sunday driving acceleration, the clutch is a distant memory.

Wish I knew what that grrrrrrrrrrrrrrrrrrrrrr noise is.
 
sounds like a ford truck

I get a similar sound ... reminds me of a Ford Explorer pickup with manual trans my Dad used to have. I get it more when starting out in 1st vs. shifting into 3rd. I do have an issue with some "notchyness" going into 3rd which is causing some alarm on my part :eek:
 
MrBlvd said:
I get a similar sound ... reminds me of a Ford Explorer pickup with manual trans my Dad used to have. I get it more when starting out in 1st vs. shifting into 3rd. I do have an issue with some "notchyness" going into 3rd which is causing some alarm on my part :eek:

Sounds like there is something loose inside the trans. I'd guess sloppy bearings somewhere. Hopefully you don't have chunks of something floating loose...

68COUGAR said:
Actually what you "discovered" is the proper way to shift. It's what semi drivers call "floating the gears". BTW: You can also float the downshift, by slightly letting off the gas, sliding the tranny into neutral, reving the engine about 1000 rpm, letting the rpm drop slowly, slight pressure on the shifter, & the tranny will drop down a gear. There is absolutely NO wear on the tranny when shifting in this manner. That is because the tranny will only shift when the gears are rotating at exactly the same speed.

How do you figure shifting this way causes "NO" wear in the transmission? Do you think the synchronizers are not involved when the clutch isn't used? I think the blocking rings are what prevents the gear from engaging until the RPM's are matched.
 
Chunks are BAD

I agree.. had a toyota 4X4 with 5spd back in the day...went thru two transmissions...not fun when they let go at highway speeds

I plan on going thru the transmission shortly... set my tax deductions to zero last year so I would have some SC spending money ... need some paint too...

yea I know uncle sam doesn't pay interest but I'm not the most disciplined individual either :D
 
so... worn blockers could account for the noise?

stock was some kind of fiber right? so after 140,000 miles, I should expect my 'floating the gears' to wear them right out? How bad is this for daily operation? should I worry, or should I just deal with the noise until I have time to rebuild my spare tranny?
 
MikeKanterakis said:
so... worn blockers could account for the noise?

stock was some kind of fiber right? so after 140,000 miles, I should expect my 'floating the gears' to wear them right out? How bad is this for daily operation? should I worry, or should I just deal with the noise until I have time to rebuild my spare tranny?


I wouldn't think worn blockers would make the noise.

I don't think "floating the gears" is particularly bad, I doubt it would really wear the trans out a whole lot fast than "normal" shifting. I do it myself quite often. However I would not fool myself into thinking that doing so is somehow going to cause absolutely no wear and make the transmission last forever.

If you have a spare trans I'd just deal with the noise, but I wouldn't wait too long on getting the spare into running condition.

These transmissions do have a magnetic drain plug. If you really are concerned, drain the fluid and look for debris. That might be reasonably cheap piece of mind.

(edit) Sorry, I mean "peace of mind" my old Iron Maiden days flashing back.(/edit)
 
Explaining the Obvious

Andy 94SC said:
(1) How do you figure shifting this way causes "NO" wear in the transmission? Do you think the synchronizers are not involved when the clutch isn't used? (2) I think the blocking rings are what prevents the gear from engaging until the RPM's are matched.
(1) Because the lower & higher gears are rotating at the same speed when the the shift occurs. So nothing is rotating on the face of the blocker.

(2) Not exactly. If you've ever driven a non-syncromeched transmission, you'd know that it's the gears themselves that "prevent" shifting if the gears are not rotating at the same speed. It's called Grinding the Gears. The blockers are there to speed up or slow down the gear facing the tapered side of the blocker. Once the blocker has done it's job & both gears are rotating at the same speed, THEN the gear change can happen. When floating the gears, YOU match the gear speeds manually. The only thing the blocker does, is engage/disengage. Nothing is sliding on the face of the blocker. Since nothing is slideing on the face of the blocker, No wear occurs.

Oh, & BTW; any M5R2 that goes 140K mi. w/o a rebuild, has been babied it's entire life.
 
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140,000 mi. Blockers

MikeKanterakis said:
(1) stock was some kind of fiber right? (2) so after 140,000 miles, I should expect my 'floating the gears' to wear them right out? (3) How bad is this for daily operation? (4) should I worry, or should I just deal with the noise until I have time to rebuild my spare tranny?
(1) Yes
(2) No, 140K mi. of clutch shifting will wear out the blockers.
(3) It's easier on the tranny than shifting With the clutch
(4) If you have a noisey trans at 140K mi., you need to deal with it, PERIOD. Floating the gears for 140,000 Miles did NOT cause the tranny to require a rebuild. 140K mi. caused the tranny to need a rebuild! I beat the Hell outa my blockers, which is why they only last me aprox. 60K mi.

68COUGAR
 
1. Iron Maiden Rocks!

2. Beat the hell out of the blockers, and ONLY got 60K out of them... Crap man. I needed new blockers 1 month after I got my first '90 Anny. My real concern is what exactly is this noise. Or more acurately, what are some of the differnet noises (Hey, What A Great Idea for a Forum, Noise Forum) that come from a failing transmission?

3. When the blockers are speeding up one gear, and slowing down another, where's the friction that effectuates this change in inertial force?
 
In theory shifting without the clutch will not cause abnormal wear. However, unless you are much more talented than the rest of us, you are most likely causing rather severe damage to some rather expensive and hard to find parts.

1) The only time the blockers are NOT working is when the perfect engagement speed has been achieved. Unless you get it perfect every time you are being hellish on the syncros AND the gears. The syncros are intended only to work against the weight of the freewheeling gears. Any more than very light pressure IS damaging.

2) Ever grind a gear doing clutchless shifting - EVER? Guess what. These are not semi truck transmissions and those aren't the syncro's grinding, those are the actual teeth on the gears themselves. Think about it, if all is well in a normal transmission, even in 400k miles you won't grind a gear. Gears are not made to sustain against grinding. It is also a fact that the syncro teeth cannot grind. It's not possible.

3)The engagement teeth on the gears are very small and the tips of them are very precisely made to lock into some also very precisely made receiving rings. The are not made to handle grinding. Ever. Grind them once and irrepairable damage has been done. Grind them repeatedly and you'll be replacing the transmission instead of rebuilding it. 68 Cougar should be telling you about that.


So...


1) Syncro's do not make any noise. You most likely have loose cluster bearings. You may be able to shim it but you may have to replace the bearings. The only way to tell is to take it apart. In any case noise = bad.

2) The loose feel in your shifter is most likely caused by the disintigration of the socket. It happens to ALL M5R2 transmissions sooner or later. It can be rebuilt or you may replace the shifter with a B&M unit.

3) It has been my experience that fiber syncro's do not wear out in even 200K miles. Rather the fibre gets brittle with age and they get damaged from overloading the lining tears out. This is evidenced from the fact that when a gear starts to go, it almost always goes very quickly. Sometimes in one shift.

4) Regarding shifting without the clutch, in a car like ours that is risky and really kind of silly. You are risking damage to expensive hard parts to save wear on inexpensive wear parts that were designed to take the abuse.

:)
 
Thanks Dave, I'd would believe you about rebuilding the top of the shifter, but I rebuilt that the second day I owned the car, which was about a year ago. And the car sat in the garage most of the summer and into November getting rebuilt by me.

On the top end of the shifter, it still feels springy and goes back to the middle every time. It's just that during shifting, it seems to slide into the gear feeling a little "lighter" than before. I'm used to the trans. feeling very stiff and deliberate. Now it's a little lighter to shift. It's so wierd, it just kinda up and happend one day. And the noise is wierd, only under heavy engine load, but then, when you WOT it, it flies!
 
68COUGAR said:
(1) Because the lower & higher gears are rotating at the same speed when the the shift occurs. So nothing is rotating on the face of the blocker.

(2) Not exactly. If you've ever driven a non-syncromeched transmission, you'd know that it's the gears themselves that "prevent" shifting if the gears are not rotating at the same speed. It's called Grinding the Gears. The blockers are there to speed up or slow down the gear facing the tapered side of the blocker. Once the blocker has done it's job & both gears are rotating at the same speed, THEN the gear change can happen. When floating the gears, YOU match the gear speeds manually. The only thing the blocker does, is engage/disengage. Nothing is sliding on the face of the blocker. Since nothing is slideing on the face of the blocker, No wear occurs.

Oh, & BTW; any M5R2 that goes 140K mi. w/o a rebuild, has been babied it's entire life.


Looks like Dave has had some more time to sit and write a reply than I have.

Mark, have you ever seen inside of one of these transmissions? If you had you would see that the synchronizers do their job everytime there is a gear change. When you are floating the gear while you are pressing the shifter and waiting for the gear to engage your synchronizer friction surface is grinding away, Exactly as Dave described.

By the way my 1989 trans was still fully operational at 170k miles, and I beat the hell out of it from 150k on up.
 
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MikeKanterakis said:
I'd would believe you about rebuilding the top of the shifter, but I rebuilt that the second day I owned the car, which was about a year ago. And the car sat in the garage most of the summer and into November getting rebuilt by me.

On the top end of the shifter, it still feels springy and goes back to the middle every time. It's just that during shifting, it seems to slide into the gear feeling a little "lighter" than before. I'm used to the trans. feeling very stiff and deliberate. Now it's a little lighter to shift. It's so wierd, it just kinda up and happend one day. And the noise is wierd, only under heavy engine load, but then, when you WOT it, it flies!

I guess I really don't understand what the problem is with the shifter. It is not supposed to be stiff or deliberate. If everything is in good shape and nothing is binding the transmission shifts very nicely. Possibly you had some of the insulation around the shifter boot jammed up under there. It doesn't take much.
 
Maybe? but shifter aside, I'm dying to know what that grrrrrrrrrrrrrrrrrrrrrrrrrrr noise is. I've pretty much decided to get a rebuild kit from driveline.com and just "HAVE AT IT!". I appreciate you guys talking this one out with me. I was hoping there was this "known" noise associated with RKE M5R2. But, I'm gonna have to stop bench fixing this tranny and start fixing this tranny on a bench. ;)
 
MikeKanterakis said:
Maybe? but shifter aside, I'm dying to know what that grrrrrrrrrrrrrrrrrrrrrrrrrrr noise is. I've pretty much decided to get a rebuild kit from driveline.com and just "HAVE AT IT!". I appreciate you guys talking this one out with me. I was hoping there was this "known" noise associated with RKE M5R2. But, I'm gonna have to stop bench fixing this tranny and start fixing this tranny on a bench. ;)

I already said what the problem is. Loose cluster bearings. Normal use wears the backing plate and creates slop. If it gets bad enough it will ruin the bearings. If it is not bad yet then you may be able to just shim the bearings. Inspect all races for wear patterns.
 
Thanks Dave. So when these cluster bearings wear out even more, what's the next step in transmission problems? even more noise, or will something just up and snap on me and then i'm stuck on the road?
 
Having been inside these things several times I've noticed that the teeth on the edge of the synchro cluster sleeve engage the teeth on the edge of the blocker and will wear both of them over time. I've had to replace one of my synchro cluster sleeves because of this. On the fiber side of the blocker facing the gear little protrusions will form on the flat surface from the steel teeth sliding over and engaging the blocker on the other side. It seems to 'push' some of the brass over the edge rather than wear it off. On the brass blockers I once used this was much worse and more pronounced than on any of the fiber blockers. I suspect that your noise is indeed a bearing. There are lots of small roller sleeve bearings between the gears and the shaft plus the thin thrust bearing between the input and output shaft. I'm thinking that this thrust bearing may be your grinding noise. You should get a new one in the rebuild kit. The synchro clusters are splined on the inside of the hub and ride on splines on the shaft and there is no sleeve bearing for them. You won't know exactly what the problem is until it's opened up, though. These transmissions are relatively easy to rebuild.
 
Thanks Mike. Do you (or anyone else) have experience with the rebuild kit from driveline.com? If so, do you recomend my ordering any other parts aside from what's already in the kit?
 
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