Drivetrain: HOW TO Fix Linkage Roll Pin on Transmission
03-26-2009, 08:28 AM
#76
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I have a set of roll pin punches from working on my AR15. Although I am not that confident of a roll pin in the shifter linkage application. Why didn't they use a stronger design, like a Grade 5 bolt perhaps? This $0.99 rollpin can cause a $2000 transaxle to blow up.
03-26-2009, 10:05 AM
#77
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I tried using bolts. Every one of them bent, resulting in a really sloppy shifter with a lot of play/ You need something that can give a little. The tension/roll pin works perfectly for this. Plus would you rather damage your trans or break roll pins?
03-26-2009, 11:06 AM
#78
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The way I understand it, breaking the roll pin can/will result in a damaged transaxle. I would rather use a captured device (pin, rod, bolt, or otherwise similar design) that wouldn't bend/break under those conditions.
Out of curiosity: What type of bolt did you use? Grade 5? Grade 8? Did you make sure that all of the loads were placed on the unthreaded portion of the bolt? An alternative might just be an unthreaded rod with the ends threaded to accept locking nuts and washers. It seems to me that the roll pin is there to both secure and locate the linkage assembly. I am not sure why GM didn't beef up this design, but perhaps I am missing something.
Out of curiosity: What type of bolt did you use? Grade 5? Grade 8? Did you make sure that all of the loads were placed on the unthreaded portion of the bolt? An alternative might just be an unthreaded rod with the ends threaded to accept locking nuts and washers. It seems to me that the roll pin is there to both secure and locate the linkage assembly. I am not sure why GM didn't beef up this design, but perhaps I am missing something.
03-26-2009, 11:17 AM
#79
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bingo, this guy hit it on the nail.
Last edited by ralliartist; 03-26-2009 at 11:17 AM. Reason: Automerged Doublepost
03-26-2009, 11:17 AM
#80
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darn it! u beat me to it! 
the reason GM didn't beef up the pin is because if they did.... further damage would occur in the tranny, for example.... the stock clutch would probably burn out faster. breaking this roll pin will not result in damaging the transaxle, breaking this roll pin will simply result in a broken roll pin and then you'll have an extremely sloppy shifter "box" and you not be able to get the car in gear. it's actually a simple fix and replacing a .99 cent roll pin is alot better than having to replace a $2k tranny
the reason GM didn't beef up the pin is because if they did.... further damage would occur in the tranny, for example.... the stock clutch would probably burn out faster. breaking this roll pin will not result in damaging the transaxle, breaking this roll pin will simply result in a broken roll pin and then you'll have an extremely sloppy shifter "box" and you not be able to get the car in gear. it's actually a simple fix and replacing a .99 cent roll pin is alot better than having to replace a $2k tranny
03-26-2009, 11:20 AM
#81
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The way I understand it, breaking the roll pin can/will result in a damaged transaxle. I would rather use a captured device (pin, rod, bolt, or otherwise similar design) that wouldn't bend/break under those conditions.
Out of curiosity: What type of bolt did you use? Grade 5? Grade 8? Did you make sure that all of the loads were placed on the unthreaded portion of the bolt? An alternative might just be an unthreaded rod with the ends threaded to accept locking nuts and washers. It seems to me that the roll pin is there to both secure and locate the linkage assembly. I am not sure why GM didn't beef up this design, but perhaps I am missing something.
Out of curiosity: What type of bolt did you use? Grade 5? Grade 8? Did you make sure that all of the loads were placed on the unthreaded portion of the bolt? An alternative might just be an unthreaded rod with the ends threaded to accept locking nuts and washers. It seems to me that the roll pin is there to both secure and locate the linkage assembly. I am not sure why GM didn't beef up this design, but perhaps I am missing something.
Personally, I used a grade 8 aircraft bolt in my linkages. I know that I'm at a higher risk now of breaking my transmission or causing severe damage. But I'd rather not be replacing roll pins every couple weeks. If I were to damage the transmission, I'd just replace it with a stronger one.
darn it! u beat me to it!
the reason GM didn't beef up the pin is because if they did.... further damage would occur in the tranny, for example.... the stock clutch would probably burn out faster. breaking this roll pin will not result in damaging the transaxle, breaking this roll pin will simply result in a broken roll pin and then you'll have an extremely sloppy shifter "box" and you not be able to get the car in gear. it's actually a simple fix and replacing a .99 cent roll pin is alot better than having to replace a $2k tranny
the reason GM didn't beef up the pin is because if they did.... further damage would occur in the tranny, for example.... the stock clutch would probably burn out faster. breaking this roll pin will not result in damaging the transaxle, breaking this roll pin will simply result in a broken roll pin and then you'll have an extremely sloppy shifter "box" and you not be able to get the car in gear. it's actually a simple fix and replacing a .99 cent roll pin is alot better than having to replace a $2k tranny
Last edited by ralliartist; 03-26-2009 at 11:20 AM. Reason: Automerged Doublepost
03-26-2009, 11:25 AM
#82
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oh a sidenote... very good how to man, i used this a month ago. my roll pin was in 3 pieces, when it happened i was freaking out because i thought my tranny blew
but then after talking to a few members they said it sounds like a broken roll pin. i was like... 
then i did the almighty "search" and found this great how-to 
03-26-2009, 11:29 AM
#83
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What you guys said makes absolutely no sense. Traditional RWD transmissions have a direct shifter attached to the gearbox (e.g. 01-04 Mustang GT with TR-3650). As long as you don't act like an idiot and hamfist the shifter without letting the synchros do their job, nothing bad will happen. You could shift normally for 100k miles and nothing would go wrong. The linkages used on later transmissions add a lot of slop and even cause missed shifts due to the movement of the engine/transmission. The linkages on the FWD cars are the worst for this because of all the slop in the different joints/components used in the linkage assembly.
From an engineer's perspective, the rollpin is there to keep the linkages attached to whatever mechanism goes into the gearbox. It would make sense to actually use a stronger Grade 8 bolt/rod with an unthreaded section directly inside the linkage to prevent flexing and slop. I could see a number of ways the slop/flexing could contribute to transaxle damage akin to improper shifting (jamming the linkage or not letting it slide into place properly). The rollpin isn't there to prevent damage to the transaxle, GM probably used those rollpins to save a few pennies on the MU3/F35 and then deny warranty since many of you race your cars.
From an engineer's perspective, the rollpin is there to keep the linkages attached to whatever mechanism goes into the gearbox. It would make sense to actually use a stronger Grade 8 bolt/rod with an unthreaded section directly inside the linkage to prevent flexing and slop. I could see a number of ways the slop/flexing could contribute to transaxle damage akin to improper shifting (jamming the linkage or not letting it slide into place properly). The rollpin isn't there to prevent damage to the transaxle, GM probably used those rollpins to save a few pennies on the MU3/F35 and then deny warranty since many of you race your cars.
03-26-2009, 11:34 AM
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traditional RWD transmissions? that has nothing to do with what we are talking about here, so bringing that up makes absolutely no sense. RWD trannys & FWD trannys are 2 completely different styles.
i understand what your saying about using a stronger bolt.... but strengthening the bolt would cause the next thing in line to give way... and thats tranny internals. like we said... replacing a .99 cent roll pin is way better than replacing a $2k tranny.
now if you were to look at the hardcore race Cobalts out there (time attack, dragsters, etc.) they probably did come out with some type of bolt to slip in there, but that's for hardcore race applications. my stock roll pin held up for 40k miles, i'm sure the one i replaced it with will hold for another 40k. i actually did "upgrade" my roll pin though, i pressed in 2 smaller pins. i'm curious to see how that'll hold up.
i understand what your saying about using a stronger bolt.... but strengthening the bolt would cause the next thing in line to give way... and thats tranny internals. like we said... replacing a .99 cent roll pin is way better than replacing a $2k tranny.
now if you were to look at the hardcore race Cobalts out there (time attack, dragsters, etc.) they probably did come out with some type of bolt to slip in there, but that's for hardcore race applications. my stock roll pin held up for 40k miles, i'm sure the one i replaced it with will hold for another 40k. i actually did "upgrade" my roll pin though, i pressed in 2 smaller pins. i'm curious to see how that'll hold up.
03-26-2009, 11:43 AM
#85
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traditional RWD transmissions? that has nothing to do with what we are talking about here, so bringing that up makes absolutely no sense. RWD trannys & FWD trannys are 2 completely different styles.
i understand what your saying about using a stronger bolt.... but strengthening the bolt would cause the next thing in line to give way... and thats tranny internals. like we said... replacing a .99 cent roll pin is way better than replacing a $2k tranny.
i understand what your saying about using a stronger bolt.... but strengthening the bolt would cause the next thing in line to give way... and thats tranny internals. like we said... replacing a .99 cent roll pin is way better than replacing a $2k tranny.
However, strengthening the bolt should NOT cause the next thing in line to give away because there is no reason to do so. If the shifter is designed properly, the reduction of flexing in the linkage at the gearbox would result in more precise shifting and less potential for damage to the synchros or other internal components.
Maybe I am explaining it wrong, but imagine yourself not pushing the shifter all the way through each position on the gates. That would result in transmission damage in the long-term since you're not engaging it properly before releasing the clutch. Added flex from a bent/broken rollpin would allow that to happen and result in transmission damage since you are relying on the linkage for precise shifting - yet it's not giving you that due to all that slop.
FWIW, I don't buy the idea that the F35/MU3 is a gearbox that needs to have linkages break to provide sloppy shifting, so I am going to borrow the Chiltons/Haynes manual and see if I can get a diagram of the F35 internals as well as look at the shifter assembly.
The reason I am curious about this is because the problem still exists on 08-09 SS/TC's and I have one on order.
03-26-2009, 11:52 AM
#86
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i understand what your saying..... and i'll admit.... having this roll pin really sucks in a few weeks i'll be upgrading my clutch & flywheel, i'd like to find out if there is a bolt that i can put in there that'll last.... basically forever. it's really hard to say tho why GM didn't "bulletproof" that part of the tranny. what really sucks is that it's not covered under the powertrain warranty
in a few weeks i'll be upgrading my clutch & flywheel, i'd like to find out if there is a bolt that i can put in there that'll last.... basically forever. it's really hard to say tho why GM didn't "bulletproof" that part of the tranny. what really sucks is that it's not covered under the powertrain warranty
03-26-2009, 02:08 PM
#87
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GM has been using this transmission since 1984 in the Saab 9000 (according to GM). The 9-3 and 9-5 also used the same transmission. Does anyone know if those vehicles had the roll pin issues as well?
03-26-2009, 02:17 PM
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I don't think it is a roll pin issue, per se. It's a wear item resulting from shifting with more force÷time than the synchros can deal with, repeatedly. Looking at the roll-pin, vs bolt/dowel/stud debate: Looks like manufacturers choose the pin due to it's constant outward pressure (until they fail). A perfectly fitted stud with washers and lock nuts would accomplish the same task, albeit they wouldn't break as easily (if that is or is not something you prefer).
03-26-2009, 03:15 PM
#89
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What kind of roll pins has everyone tried?
I found these at McMaster:
95765A417
420 SS Extra Strength Coiled Spring Pin 3/16" Diameter, 1" Length
In stock at $7.26 per Pack
This product is sold in Packs of 10
4500 lb double shear strength, Rockwell hardness C46
Suggest hole size is 0.185"-0.192"
Has anyone measured the ID of the linkage assembly hole?
I found these at McMaster:
95765A417
420 SS Extra Strength Coiled Spring Pin 3/16" Diameter, 1" Length
In stock at $7.26 per Pack
This product is sold in Packs of 10
4500 lb double shear strength, Rockwell hardness C46
Suggest hole size is 0.185"-0.192"
Has anyone measured the ID of the linkage assembly hole?
03-26-2009, 03:21 PM
#90
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the pin size is 3/16"x1"........i think, it's in the first post. i just bought a little pack of roll pins from AutoZone, cost $2.99, it had the roll pin i needed and like i said, i put 2 smaller ones inside it to see if that would help
Last edited by rallycobalt06; 03-26-2009 at 03:39 PM.
03-26-2009, 03:31 PM
#91
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www.mcmaster.com
95765A417
3/16" OD, 1" overall length, heavy-duty (30% stronger than regular steel), and it is a coiled pin, think of it has being 1 sheet of spring steel wrapped as an eggroll.
I noticed a lot of people just used the cheap stuff they buy at the counter. The quality and strength could vary greatly.
95765A417
3/16" OD, 1" overall length, heavy-duty (30% stronger than regular steel), and it is a coiled pin, think of it has being 1 sheet of spring steel wrapped as an eggroll.
I noticed a lot of people just used the cheap stuff they buy at the counter. The quality and strength could vary greatly.
03-26-2009, 03:42 PM
#92
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www.mcmaster.com
95765A417
3/16" OD, 1" overall length, heavy-duty (30% stronger than regular steel), and it is a coiled pin, think of it has being 1 sheet of spring steel wrapped as an eggroll.
I noticed a lot of people just used the cheap stuff they buy at the counter. The quality and strength could vary greatly.
95765A417
3/16" OD, 1" overall length, heavy-duty (30% stronger than regular steel), and it is a coiled pin, think of it has being 1 sheet of spring steel wrapped as an eggroll.
I noticed a lot of people just used the cheap stuff they buy at the counter. The quality and strength could vary greatly.
03-26-2009, 03:49 PM
#93
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With respect, before I get flamed, the reason I brought up a RWD gearbox is because the shifter is directly attached to the gearbox on some models. A FWD gearbox/transaxle is essentially the SAME, except your shifter is remotely attached - but it still has to interface with the gearbox at some point. A Corvette would be an example a remotely mounted RWD transaxle application (similar to a FWD application like the Cobalt) - again, the same concept applies. Instead of the shifter being directly attached, you work through several linkages. It only makes sense to eliminate as much slop as possible to give you precise control over the internals.
However, strengthening the bolt should NOT cause the next thing in line to give away because there is no reason to do so. If the shifter is designed properly, the reduction of flexing in the linkage at the gearbox would result in more precise shifting and less potential for damage to the synchros or other internal components.
Maybe I am explaining it wrong, but imagine yourself not pushing the shifter all the way through each position on the gates. That would result in transmission damage in the long-term since you're not engaging it properly before releasing the clutch. Added flex from a bent/broken rollpin would allow that to happen and result in transmission damage since you are relying on the linkage for precise shifting - yet it's not giving you that due to all that slop.
FWIW, I don't buy the idea that the F35/MU3 is a gearbox that needs to have linkages break to provide sloppy shifting, so I am going to borrow the Chiltons/Haynes manual and see if I can get a diagram of the F35 internals as well as look at the shifter assembly.
The reason I am curious about this is because the problem still exists on 08-09 SS/TC's and I have one on order.
However, strengthening the bolt should NOT cause the next thing in line to give away because there is no reason to do so. If the shifter is designed properly, the reduction of flexing in the linkage at the gearbox would result in more precise shifting and less potential for damage to the synchros or other internal components.
Maybe I am explaining it wrong, but imagine yourself not pushing the shifter all the way through each position on the gates. That would result in transmission damage in the long-term since you're not engaging it properly before releasing the clutch. Added flex from a bent/broken rollpin would allow that to happen and result in transmission damage since you are relying on the linkage for precise shifting - yet it's not giving you that due to all that slop.
FWIW, I don't buy the idea that the F35/MU3 is a gearbox that needs to have linkages break to provide sloppy shifting, so I am going to borrow the Chiltons/Haynes manual and see if I can get a diagram of the F35 internals as well as look at the shifter assembly.
The reason I am curious about this is because the problem still exists on 08-09 SS/TC's and I have one on order.
Does that make sense? It shouldn't be sloppy at all when the correct roll pin is used.
03-26-2009, 03:51 PM
#94
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But, I used a 3/16"thick x 1 3/4" long Grade 8 Aircraft Bolt and it will not break. But, I do risk breaking the trans.
Last edited by ralliartist; 03-26-2009 at 04:54 PM.
03-26-2009, 03:59 PM
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03-27-2009, 07:02 AM
#97
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The closest match to a cap screw (bolt) I could find on McMaster:
94081A153
10-24 thread (0.190" OD), 2" long, made of titanium. It is not rated for any SAE Grade, but the min. tensile strength is 50,000 psi (I found a Grade 8 bolt was rated for 150,000 psi). The cost is $4.72 per bolt.
Be aware that the threaded portion of any screw/bolt is the weakest link. It is best to use an unthreaded pin/rod and just thread it at the end where you need to use a nut/cap to capture the pin/rod.
94081A153
10-24 thread (0.190" OD), 2" long, made of titanium. It is not rated for any SAE Grade, but the min. tensile strength is 50,000 psi (I found a Grade 8 bolt was rated for 150,000 psi). The cost is $4.72 per bolt.
Be aware that the threaded portion of any screw/bolt is the weakest link. It is best to use an unthreaded pin/rod and just thread it at the end where you need to use a nut/cap to capture the pin/rod.
