'69 4 speed downshift problem: REVISITED
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From: Raleigh NC
'69 4 speed downshift problem: REVISITED
To recap: Had a problem with the muncie downshifting from 4th to 3rd, no grinding what so ever, just wont downshift into third. While holding the clutch I can go from 4th to 2nd back into 3rd, no problem, just wont go from 4th to 3rd.
On Sunday Harps and I changed the shifter linkage rods mainly because the reverse rod had been broken and rewelded sometime in its lifetime.
We put new 80w-90 gear oil into the case and we lengthened the 3rd-4th shifter rod to see if that would help.
The car shifts really smooth now but we were unable to correct the downshift problem. I dont think it is the synchros or gears in the tranny because there is no grinding and everything else upshifts and downshifts fine. Could it possibly be the shifter itself. Any more ideas?
Kyle
If interested here is the previous post.
http://forums.corvetteforum.com/show...128&forum_id=3
On Sunday Harps and I changed the shifter linkage rods mainly because the reverse rod had been broken and rewelded sometime in its lifetime.
We put new 80w-90 gear oil into the case and we lengthened the 3rd-4th shifter rod to see if that would help.
The car shifts really smooth now but we were unable to correct the downshift problem. I dont think it is the synchros or gears in the tranny because there is no grinding and everything else upshifts and downshifts fine. Could it possibly be the shifter itself. Any more ideas?
Kyle
If interested here is the previous post.
http://forums.corvetteforum.com/show...128&forum_id=3
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Joined: Jul 2000
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From: Raleigh NC
I used a locating gauge to keep the shifter in neutral. Then after replacing the shift rods, I lengthened the 3rd-4th shift arm by adjusting the screws on the end near the front of the tranny (front of the car), thereby lengthening the arm.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
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From: Tampa Bay FL
What led up to the 4-3 shift problem to begin with? I had a problem with a manual trans where one of the selector forks inside the trans somehow got bent (maybe when that guy pulled out in front of me... I was in an '86 Hyundai). It took a long time for the problem to become apparent but ultimately the fork had to be adjusted/bent. Wondering if your problem could be similar; an internal trans adjustment.
Team Owner
Joined: Jul 2004
Posts: 40,381
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From: Redondo Beach, California
I too had trouble with the 3rd-4th shift rod. I couldn't get my shift levers properly alighned after replacing the shifter and rods with all new. 3rd-4th shifts were not consistently smooth. I finally realized that the 3-4 rod seemed to be short, I was running out of adjustment range. I happened to have another new 3-4 rod, so I got it and compared with the one I had installed. The new 3-4 rod was about 3/8 inch shorter than my spare new rod! Replacing the rod, the transmission now seems to shift smoothly.
For people who don't have a lot of experience aligning Muncie shifters, you really need to have the alignment shim tool for the shifter. There's a small slot that you insert the shim to guarantee neutral. The only place I've found them for sale is Corvette Central. PN 532088. It appears the shim is only referenced in their C2 catalog. It sells for $1.95.
For people who don't have a lot of experience aligning Muncie shifters, you really need to have the alignment shim tool for the shifter. There's a small slot that you insert the shim to guarantee neutral. The only place I've found them for sale is Corvette Central. PN 532088. It appears the shim is only referenced in their C2 catalog. It sells for $1.95.
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From: Raleigh NC
Originally Posted by 68/70Vette
I too had trouble with the 3rd-4th shift rod. I couldn't get my shift levers properly alighned after replacing the shifter and rods with all new. 3rd-4th shifts were not consistently smooth. I finally realized that the 3-4 rod seemed to be short, I was running out of adjustment range. I happened to have another new 3-4 rod, so I got it and compared with the one I had installed. The new 3-4 rod was about 3/8 inch shorter than my spare new rod! Replacing the rod, the transmission now seems to shift smoothly.
For people who don't have a lot of experience aligning Muncie shifters, you really need to have the alignment shim tool for the shifter. There's a small slot that you insert the shim to guarantee neutral. The only place I've found them for sale is Corvette Central. PN 532088. It appears the shim is only referenced in their C2 catalog. It sells for $1.95.
For people who don't have a lot of experience aligning Muncie shifters, you really need to have the alignment shim tool for the shifter. There's a small slot that you insert the shim to guarantee neutral. The only place I've found them for sale is Corvette Central. PN 532088. It appears the shim is only referenced in their C2 catalog. It sells for $1.95.
Race Director
Joined: Feb 1999
Posts: 16,978
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From: In Dreams There Is Truth Ohio
The tranny has to be in neutral, the shifter arms in neutral, place the pin in the shifter and adjust the rods....when adjusted properly, the rods will slide into the tranny and shifter arms without any jiggling....like a hot knife going through warm butter...
Last edited by GDaina; Oct 24, 2005 at 04:05 PM.
Team Owner
Joined: Jul 2004
Posts: 40,381
Likes: 789
From: Redondo Beach, California
Originally Posted by kywils
Thanks. I did used the shim tool (locating guage) to hold the neutral position. So you are saying you shortened the rod? I actually lengthened the rod, maybe I should shorten it and see if that works.
(My original rod was bent. I bought a new rod from Volunteer Vette. Later I realized that my original shifter was a little worn. I had a new shifter on the shelf, and I installed it. Have gone this far I decided to go to all new shifter rods, so I ordered the entire set from Volunteer Vette. The new rod in this set was slightly shorter than the new single rod I initially purchased. It's amazing that one rod would be of different length, but I guess things like that happen.)
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Joined: Jul 2000
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From: Raleigh NC
I'm beginning to think it may be the shifter itself causing the downshift problem. Maybe its loose on the bracket. I will have to check. I am almost positive its not an internal tranny problem, and the shift linkage is adjusted properly, I will just have to check the shifter itself.
Le Mans Master
Joined: Sep 2004
Posts: 6,019
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From: Conroe Texas
Originally Posted by kywils
To recap: Had a problem with the muncie downshifting from 4th to 3rd, no grinding what so ever, just wont downshift into third. While holding the clutch I can go from 4th to 2nd back into 3rd, no problem, just wont go from 4th to 3rd.
On Sunday Harps and I changed the shifter linkage rods mainly because the reverse rod had been broken and rewelded sometime in its lifetime.
We put new 80w-90 gear oil into the case and we lengthened the 3rd-4th shifter rod to see if that would help.
The car shifts really smooth now but we were unable to correct the downshift problem. I dont think it is the synchros or gears in the tranny because there is no grinding and everything else upshifts and downshifts fine. Could it possibly be the shifter itself. Any more ideas?
Kyle
If interested here is the previous post.
http://forums.corvetteforum.com/show...128&forum_id=3
On Sunday Harps and I changed the shifter linkage rods mainly because the reverse rod had been broken and rewelded sometime in its lifetime.
We put new 80w-90 gear oil into the case and we lengthened the 3rd-4th shifter rod to see if that would help.
The car shifts really smooth now but we were unable to correct the downshift problem. I dont think it is the synchros or gears in the tranny because there is no grinding and everything else upshifts and downshifts fine. Could it possibly be the shifter itself. Any more ideas?
Kyle
If interested here is the previous post.
http://forums.corvetteforum.com/show...128&forum_id=3
