Dkarr

I'm very excited to finally have my 69 back on the road after a year of building (I'm sure some of you guys have seen my other posts along the way). However, my freshly rebuilt m20 is making a very disturbing noise when I go into 3rd with any force. The best way I can describe it is like a clunking sound that almost sounds like it's bouncing on a spring (think CLunk - nk - nk -k). If I really shift hard it grinds and clunks. SO here is a break down.

• It only happens when the trans is warm (after about 5-10 minutes of driving) and it only happens if I shift quickly.
• If I gently shift into 3rd it's just as smooth as the other gears. No noise.
• I get the same sound going from 2nd to 3rd or 4th to 3rd.
• None of the other gears make noise
• I tripple checked that my hurst was lined up exactly, no issues I can see with the linkage
• If I am in 3rd gear, push the clutch in and press hard forward on the shifter it will grind a little (while still in gear).
• I am running redline 75/90NS oil in the trans. It is full.
• I am running a brand new Centerline DF clutch. Followed all alignment procedures when installing and made 100% sure that my Lakewood bell was dialed in with accepted amount of runout. Brand new pilot bearing.

I plan on contacting my trans guy tomorrow but just want to get opinions on here to double check any assessment he makes. Needless to say... I'm pretty ticked off about this. Especially since I've already dropped $400+ on getting 2 1/2 inch exhaust run under the car... with an x pipe right behind the tail shaft, whole system is welded up. I got under the car and have concluded that there would be almost no way to get the trans out... without cutting the exhaust. I sure hope this isn't a syncro problem.

Thoughts??

oldalaskaman

best advice, talk to your trans man, anything else would be a quess

RU7376vettes

Did you use the Hurst set-up rod or similar piece of bar stock to line up the shifter when installing the rods? Which Hurst do you have? The Competition has adjustable stops that must also be properly adjusted. It is possible that the one for 3rd is not properly adjusted. If all this checks out, get some details on what all was done during the rebuild of the transmission by your transmission guy. Did he replace sliders as well as synchronizer rings? Good luck, you will get it sorted out!

Unk

steved400

RU probably has the best starting point.

Dkarr, no disrespect intended but I have to ask if you really know how to adjust the rods? Do you know to put the alignment pin in the shifter? If you didn't use Hurst's Corvette rod kit you are probably looking at issues there.

As for the tranny being the problem, your tranny guy could have done something wrong or there may be a part still bad even though he rebuilt it. How did he rebuild it would be the question, just gaskets and syncs or more in depth than that?

I am pretty good at rebuild both the shifter and the Muncies; if you are near Tulsa come over with it and I'll try to fix it for you

Oh, if your X is behind the crossmember it shouldn't be an issue.

Dkarr

Steved400, no disrespect taken, that's why I wanted to throw this question out. I printed off some basic directions on adjusting the rods. I put the alignment pin in the hole at the bottom of the shifter and aligned all of the rods afterward. It lined up nicely and seemed to shift good without any binding.

As for the rods, I have no clue. I bought this shifter from a friend that had it in his 69 vette. Worked great in his car. He only had it in for a few months before he tore the car down for a rebuild so there arent many miles in the shifter.

I'm not sure what model it is. It does NOT have the screws on the front and back of the shifter base (which I think are specific to the competition shifter). I'll post a pic of it soon.

steved400

If the shifter was working fine in another Corvette then that shouldn't be the issue.

The reason the correct rods are important is the mounting bracket is different than others to get it up in the hole. Also there is a special spacer for the specific Hurst handle; then you need the correct rods to match all that. But since you have transplanted a working shifter; and you have probably adjusted it correct, you may indeed have issues in the tranny.

There are several things that could have been down wrong on the tranny rebuild or more parts worn out; looks like you will need to take it back out for inspection.

Dkarr

Here Are the pics. Anyone know what model this is?


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steved400

The only thing I see that might not be correct by the book is your shifter mounting bracket.

But as long as the handle goes through the hole and your rods are aligned, I don't think this will be an issue.

Garys 68

There's a lockout mechanism in the Muncie side cover that prevents engagement of the 1/2 and 3/4 shift forks at the same time. If your linkage was not adjusted correctly, it would not go into 3rd gear at all or it wouldn't engage fully and pop out of gear. It sounds like yours is grinding while your shifting with the clutch depressed.
The only other linkage related issue would be with the reverse gear, it doesn't have a lockout. But that linkage is on the opposite side of the 3/4 linkage.
The fact that it isn't doing it in other gears indicated your clutch is disengaging and nothing is generally binding up in the trans.
Not sure about the clunking, but the grinding indicates a synchro issue. Let the trans guy know and take him for a ride.

Dkarr

Well, just talked to the trans man... he says he's 99% sure it's a syncro. I'm taking it to him early next week to find out how we are going to make it right.

If he's not willing to yank this thing out for me it's going to be really hard not to resort to physical violence...

oldalaskaman

if he's honest enough to identify the issue, I think he'll do whats required.

steved400

I personally think it's more than that, but wish you the best of luck.

Garys 68

Outside of a distorted case (elongated countershaft hole), that's the most labor intensive fix. Good to see he's honest about it.
Btw, if you have the small countershaft, check with him about bushing it. I think it was only $75, well worth it in my opinion.

Dkarr

I hope he stays honest about it. I'm trying to see the glass half full here.

What else do you think could be going on? Im no expert on muncies so any advice on what I should be asking him is much appreciated.

steved400

There really is no way to know without getting into it.

If he took the counter shaft out; did he get all the pins back in? Things like this you can never know; did he do something wrong or miss a part? You just can't know without diving into it. This doesn't make your guy a bad person; sometimes mistakes are made, I know I make plenty of them

If we were close enough I would be more than happy to tear it down with you standing here and try to figure it out; maybe you could try it yourself?

How far away from me are you anyway?

Dkarr

Pretty far... I'm in Georgia. I tell you what, when I get the car back to the trans guy and the trans comes out I'll get him to give me a complete run down of the situation along with pictures. I'll post those up here and see if you have any input on what he claims to be the diagnosis. Hopefully it's something simple.

Thanks for the offer to help!

RU7376vettes

Hurst has a "Universal" model that doesn't have the stop bolts on it. You can check by looking on the body of the shifter for part numbers. Email Hurst and they can confirm the model. The Universal model doesn't quite line up with the stock opening, it is a little left of the stock position and would hit the console. A spacer between the shift lever and the a shifter may help the clearance situation. That should not have caused your grinding noise. Looking forward to the report from the transmission guy.The new syncro's may be a little tight or one of then has a small burr on it.

Unk

steved400

A shame you're so far away.