Author Topic: What Would You Do? (Read 18332 times)

Vince · « **on:** September 07, 2011, 09:22:31 PM »

My 1969 Z/28 may be in need of a new transmission given the worst case scenario. When I was driving it this morning it seemed to be much rougher than normal, sort of like the tires were out of balance or some kind of vibration was happening. When I went to put the tranny into first gear to pull away from a stop sign it wouldn't go into gear, any gear. It was like the shifter was hung up in the neutral position. I finally was able to get it to go into the position where reverse is, but the car would not move. When the tow truck driver got there and couldn't winch it onto the flat bed he said that it was stuck in gear. After fooling around with the linkages from under the car and with my riding in the car and depressing the clutch he was able to get it loaded onto his truck. My car is currently at the transmission shop, but they haven't got back to me yet with any findings.
I know that the current tranny in my car is not the original one. As far as I know it is a M21 from 1966. I know my car came originallly with a Muncie M21 from the factory. Now for my questions as I wanted to give as much info as I could.

1. If it is recommended that I get a new or rebuilt transmission should I get another M21? Since I cannot get the original one would now be a good time to put a M22 in my car? I have been thinking about doing this for a couple of years now.
2. Where is the best place to look into a new M21 or M22? I have been thinking about Medatronics?
Thanks for any and all input.

bertfam · « **Reply #1 on:** September 07, 2011, 09:56:18 PM »

Vince, there's a very good possibility that the problem is in the shifter itself and NOT in the transmission. When they wear, Hurst shifters are notorious for gettiing stuck between gears. Usually between 1st and 2nd, but it can also get stuck between 3rd and 4th, and even reverse and 1st!

It's happened to me MANY times in the past (usually when I'm all dressed up!!), and you have to crawl up under the car to get it released.

As a matter of fact, I just bought a new kit to rebuild the one in my 68! It's not hard to rebuild them and there are a few sites that give good instructions. HERE'S one from Yenko.net, and HERE'S another from one of those "other guys" forums. (same basic shifter)

You'll need a kit and HERE'S where I got mine (P/N INL10199) for only $22.00 plus shipping. HERE'S the specific page... (bottom left.)

Back in the olden days when I was young (yes, we had cars back then!), Hurst would rebuild your shifter for free if you brought it to a show, swap meet, a racing event, etc... If they were there, they would always have a few employees that would rebuild your shifter while you wandered around. You can still get it rebuilt by Hurst, but it's FAR from free now. The last time I checked, it was around $200 for them to rebuild it. And really, all it requires are new shim plates. Go figure. However, if you want them to do it, fill out the form on THIS PAGE and in a few weeks it'll come back ready for another 20 years!

Ed

firstgenaddict · « **Reply #2 on:** September 07, 2011, 10:05:50 PM »

I agree with ED, if it is the original shifter with the rubber inserts by all means check that first, however if asking for trans choice advice...
Do you have a reason for wanting a M22 (Same ratios as a M21)other than that ROCKCRUSHER sounds better rolling off the tongue (the trans sounds better to some of us as well)? They are noisy, expensive, and strong... unless you need the STRONG part then why?

Not knowing your rear end ratio assuming a 3.73 or a 4.10...consider a M20.

A M20 has a steeper first 2.52 vs a 2.20, which with the 302 is extremely helpful in getting the motor spinning and thus making power.

If you have:
3.73's with a M21 or M22 the effective first ratio is 8.206
4.10's with M21 or M22 effective is 9.020

3.73's with a M20 effective ratio is 9.396 ~ steeper than a 21 with 4.10's... interesting isn't it?
4.10's with M20 effective ratio is 10.332 ~ IMHO this is the COMBO... it will LAUNCH the car in first... also makes it very very difficult to stall the car in first EVER.

I hope this makes some sense...

1971ls6 · « **Reply #3 on:** September 08, 2011, 12:14:33 AM »

Could not agree more. I tested it back to back in my vette with first the wide ratio and 4.11' broke it on the first pass of a 2 day race, changed it out in the pits with the close ratio and lost 3/10ths and 3 mph. I have a real nice liberty built m21 fine spline with a steel mid plate and bushed case that I would love to trade for a wide ratio. When I rebuilt the wide ratio, I went with the m22 wide ratio and the maserio Italian gears. 3.73 gears and m21's are not first gear friendly. I am now running a 4.30, all I need at a stop light is 1st and 4th, 2 speeds are nice on the street.

KurtS · « **Reply #4 on:** September 08, 2011, 01:12:04 PM »

Realize the "wide ratio" is only referring to the gap between 3rd and 4th. M20 is better.

Or a Tremec 5-speed.

L78 steve · « **Reply #5 on:** September 08, 2011, 01:50:00 PM »

If you need a trans built, Medatronics is the place. Go M20. 21's and 22's were for road racing.

JohnZ · « **Reply #6 on:** September 08, 2011, 03:43:18 PM »

You have a common shifter and linkage issue, not a transmission issue.

Vince · « **Reply #7 on:** September 08, 2011, 04:39:32 PM »

Thank you all for your answers and insights. All your combined knowledge regarding Camaros specifically is much appreciated. I wish I knew 1/10 of what you guys know.

sftibbs · « **Reply #8 on:** September 12, 2011, 01:54:11 AM »

I'm having a problem removing the shifter. Can the shifter be removed with the transmission in place? Does the shifter mounting bracket need to be removed?

tmodel66 · « **Reply #9 on:** September 12, 2011, 02:00:49 AM »

Yes the shifter comes off in one piece. It unbolts from the transmission.

sftibbs · « **Reply #10 on:** September 12, 2011, 03:38:59 AM »

I understand that. I have it unbolted and ready to remove but it's getting hung up. Will it come all the way out if I work with it, or does something else (e.g. transmission) need to be removed first. Thanks.

MyRed67 · « **Reply #11 on:** September 12, 2011, 04:47:12 AM »

Are you trying to go down and out with the shifter? Are all the linkage rods removed?

sftibbs · « **Reply #12 on:** September 12, 2011, 03:23:07 PM »

Yes all linkage is removed, and I want to go down and out with it. Seems to be getting hung up on the mounting bracket and maybe the transmission. If I can finagle it out I will, just wanted to see if someone has had the experience and knows what needs to be done.

bertfam · « **Reply #13 on:** September 12, 2011, 03:38:18 PM »

Did you remove the stick first? It won't come out if the stick is still attached.

And yes, you sometimes have to putz with it a little to get it out!

Ed

sftibbs · « **Reply #14 on:** September 12, 2011, 04:07:23 PM »

I havn't done that yet, but I will. When I put it back together, I assume the shifter gets bolted into place and then the stick gets put back in from the top?

bertfam · « **Reply #15 on:** September 12, 2011, 04:13:48 PM »

Quote

When I put it back together, I assume the shifter gets bolted into place and then the stick gets put back in from the top?

Yep. If you have a console you have to remove the upper shifter plate and the boot to gain access, but after that it's not that hard to do.

Ed

firstgenaddict · « **Reply #16 on:** September 21, 2011, 07:40:03 PM »

To remove the bayonet handle you will need a piece of thin steel to slide down the sides of the handle to release the clip.
I usually use 2 pieces of STEEL BANDING 3/4" wide 4-5" long. shove one down each side and pull the handle up and out.

bertfam · « **Reply #17 on:** September 21, 2011, 11:52:25 PM »

I just rebuilt mine this weekend and as I stated above, it's very easy to do. However, PLEASE be very careful of the thin shim. You can cut yourself very easily if you're not careful (don't ask how I know).

Ed

Vince · « **Reply #18 on:** October 05, 2013, 01:02:25 AM »

Twice now in the past 2 years my 1969 Z/28 with a M-21 trans (non-original) has after coming to a stop at a stop sign and then trying to put it into first gear to pull away has had the tranny jam in a gear, usually second, or stay in neutral without being able to put it into any gear. The shifter handle will just freeze up and not be able to be moved at all. I've had to have it towed both times. The first time the transmission shop could find nothing wrong with it (it was stuck in second gear when it went into their shop they stated); they cleaned the shift rods, lubed them and everything was fine until this past Wed. when the same thing happened again. It is currently in the same shop. I haven't heard back from them yet. I've owned this Z for 17 years and have had no problem with the trans prior to this first incident in 2011 and now again this week. Any ideas? I posted about this problem back in probably around Sept., 2011 but can't find my original post asking about this problem. Thank you in advance for any advice, ideas, fixes, etc.

Vince · « **Reply #19 on:** October 05, 2013, 01:12:40 AM »

OK, I found my original thread. It was under the title What Would You Do? Sounds like I need a shifter and or linkages rebuild?

69Z28 · « **Reply #20 on:** October 05, 2013, 01:42:21 AM »

Could the problem be inside the trans?

z28z11 · « **Reply #21 on:** October 05, 2013, 04:19:56 AM »

Could be wear or broken "dogs" in the syncro sleeve area - there are three of the little alignment dogs riding in each sleeve, a break or advanced wear could cause them to misalign enough to hang it in gear. Does sound more like an internal problem rather than a shifter problem. Did the shop tell you they managed to free it up by removing the shift rods and manually shifting the gear from the selector back to neutral ? If they did, it might be a shifter problem. In any case, try rebuilding the shifter first, as it's cheaper to do, or you're doomed to pull the thing and go through it to isolate the worn/broken parts.

I had my M21 lose the ability to go into reverse one day long ago - I limped into the station I worked at, pulled the trans and found the problem when I pulled the tailshaft housing off - turned out the spring steel shim (keeper) holding the speedometer gear in place on the mainshaft had snapped, and lodged under the selector preventing the reverse gear from moving - I replaced it, stuck it back together, and 38 years later it's still in one piece. Muncie's finest, still one of the best ever four speed transmissions in my opinion.

Regards,
Steve

69pace · « **Reply #22 on:** October 06, 2013, 03:35:32 AM »

Vince - So you have not rebuilt the shifter as suggested in this thread back in 2011?
That is where I would start.
Common for them to jam or lock out in 1-2 or miss 2nd when the old rubber bushings rot or the carrier gets sloppy.
Rebuild kits are about 100 bucks or you can send it to Hurst to be rebuilt. Also I suggest using the pit pack bushings that are steel or the hardened steel versions as the original rubber style or the later plastic ones are just bad news all the way around.

Your trans has been serviced a few times and if there was something wrong with the indents or the forks that would have been found if it is a good shop.

I've been in your shoes a couple times in the past 30 years. Always at night in less then "hey lets get underneath and see whats up" conditions.
I have been able to set it straight and get home by shutting down and going through the following pattern:

Start by learning how to double clutch.
Since you won't be spinning engine power you need to have some slight movement on the trans without grinding your gear box to scrap under engine power.
The double clutching moves the spindle just enough to work out the jam. So clutch in, clutch out, then clutch in and SLOWLY try to pull her into neutral gate.
This may not happen the first few times so be patient and slowly move through the gates, brute force is not necessary, required or desired.

Once in neutral clutch out, then clutch in, clutch out clutch into reverse since reverse can actually be thrown while you are actually in 1-2 or 3-4 since there is no indent to lock-out for reverse in the tail like there is on 1-2 3-4 under the cover plate. If the 1-2 indent lock-out failed you would hear grinding into reverse if you were under engine power.

Once in reverse double clutch go neutral again then double clutch first, double clutch back to neutral then take a deep breath make peace with your God and double clutch second. If she grabs second you are more then likely clear of the jam. You can put her back in neutral, start it up and slowly clutch out and if you go nowhere you are clear and in neutral. Slowly crawl forward with first, then neutral, then backward in reverse, then neutral. Head home. Just be slow and steady shifting home cause the misalignment will still exist and could hit you at any 2nd gear shift you make. Worse time I had it was about 40 minutes of footwork before she cleared.

If the jam doesn't clear the first sequence continue the pattern double clutch to third, back to neutral then up to fourth then back to neutral then reverse. Then start the sequence all over again. Eventually she will clear the jam and you can get home unless it is truly a mechanical failure.

The first time I ran into this I discovered that I had a mix of OEM factory Hurst Comp plus and Hurst Aftermarket Comp plus rods, levers and mount. The rubber bushings were also like goo. There is a difference between the factory hardware and mount and what Hurst sold as aftermarket conversion units under the Competition Plus name and you need the right set for your shifter. Once I set that straight I neglected to maintain the system and a loose lower mount bolt and sloppy bushings caused another incident a few years later when the plastic bushings cracked and bound 2nd up again.

The steel bushings, good lock washers on the lower mounting bolt and regular inspections are my defense against another incident.

Vince · « **Reply #23 on:** October 07, 2013, 11:33:54 PM »

Thanks for your input and answers, guys. When one knows as little as I do mechanically, your knowledge is greatly appreciated.

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Author Topic: What Would You Do? (Read 18332 times)