View Poll Results: T56 Shift Fork Pads
Older Stock shift fork pads (White)
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T56 Shift Fork Pads - Bronze or Stock Nylon ?
06-04-2010, 07:28 AM
#1
T56 Shift Fork Pads - Bronze or Stock Nylon ? Ok.. Here's a recent discussion and I'd love to get feedback from builders, DIY'ers, and anyone else with an opinion or hard data. I've cut&paste my thoughts from another thread:
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Shift Fork Pads: Aftermarket Bronze, Stock Nylon, or other?
This was in a magazine article from a National Trans builder:
http://www.camaroperformers.com/cama.../photo_15.html
My points to this debate would be:
1) I've never pulled "broken" bronze pads out of a T56 like I have the nylon ones. And when the pads go, they usually take out several hundred dollars worth of other parts with them.
2) The bronze pads I've dealt with, tend towards the upper end of the tolerance and I can see them clearancing themselves but then not wearing further.
3) When the fork is in neutral for that gear pair, there should be no side loading on the pads to cause abnormal wear. (unless the driver is resting their hand on the shift **** after shifting)
4) The ATF fluid will lubricate the pad/slider interface during normal operation. Unless it wasn't sufficiently lubricated during assembly/breakin or if it's a primary drag car that won't get as much fluid splash during 1/4-mile (1/8-mile) runs..
So I would love to see more data on the topic. I'm sure I haven't touched a fraction of the T56s you guys have, but when I'm seeing over 50% failure rate of one or more nylon pads in the units I have opened up, I think something is going on.
------------
Shift Fork Pads: Aftermarket Bronze, Stock Nylon, or other?
This was in a magazine article from a National Trans builder:
http://www.camaroperformers.com/cama.../photo_15.html
My points to this debate would be:
1) I've never pulled "broken" bronze pads out of a T56 like I have the nylon ones. And when the pads go, they usually take out several hundred dollars worth of other parts with them.
2) The bronze pads I've dealt with, tend towards the upper end of the tolerance and I can see them clearancing themselves but then not wearing further.
3) When the fork is in neutral for that gear pair, there should be no side loading on the pads to cause abnormal wear. (unless the driver is resting their hand on the shift **** after shifting)
4) The ATF fluid will lubricate the pad/slider interface during normal operation. Unless it wasn't sufficiently lubricated during assembly/breakin or if it's a primary drag car that won't get as much fluid splash during 1/4-mile (1/8-mile) runs..
So I would love to see more data on the topic. I'm sure I haven't touched a fraction of the T56s you guys have, but when I'm seeing over 50% failure rate of one or more nylon pads in the units I have opened up, I think something is going on.
06-04-2010, 07:39 AM
#2
My feeling is that with enough missed shifts and worn or damaged synchros, the nylon pads have more force on them to make the shift and eventually wear thin and crack. For my rebuild, I went with nylon since my trans had several hard passes and only 1 pad was cracked but had not fallen apart (on the 5/6 fork).
06-04-2010, 12:24 PM
#4
I have seen cracked and broken stock pads in both 1-2/3-4 size and 5-6/R size. Most led to inability to completely enter a particular pair of gears (such as 5-6) or a partial shift condition which led to grinding of synchronization teeth and then a lack of range of motion at the fork which led to an inability to shift a particular gear at all.
I've seen smashed bronze pads which did not disable the ability to shift, but did change the amount of shifter action necessary to complete the shift.
I have no experience with Vespel, nor have I seen any issue that seemed to be heat related.
I do believe in the chicken vs. the egg progression of symptoms, a non-releasing clutch leads to aggressive shifter motion by the driver which leads to an impact of the pads against slider groove, which could be considered "above and beyond normal use" unless you consider a non-releasing Hyd. TO Brg. on an LS to be pretty normal.
Other than that... I'm putting a 1-6 billet keys / bronze pads LT1 box in a big CID SBC car this weekend.
I've seen smashed bronze pads which did not disable the ability to shift, but did change the amount of shifter action necessary to complete the shift.
I have no experience with Vespel, nor have I seen any issue that seemed to be heat related.
I do believe in the chicken vs. the egg progression of symptoms, a non-releasing clutch leads to aggressive shifter motion by the driver which leads to an impact of the pads against slider groove, which could be considered "above and beyond normal use" unless you consider a non-releasing Hyd. TO Brg. on an LS to be pretty normal.
Other than that... I'm putting a 1-6 billet keys / bronze pads LT1 box in a big CID SBC car this weekend.
06-04-2010, 12:33 PM
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Good read, yeah end of this year i plan to have my tranny rebuilt, I think im gonna have my master cylinder made in to an adjustable one because i think there might be a problem with the clutch disengaging. Right now my tranny is stock 80k miles and pops out of 3rd if i don't hold it in there for literally just one sec.
06-04-2010, 01:31 PM
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For a stock rebuild, I install stock fork pads. If I know they are going to beat on the unit, I try to convince them to upgrade the keys for the 1-2 and 3-4 syncro assembly along with installing bronze fork pads through out the unit.
06-04-2010, 03:00 PM
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06-04-2010, 04:40 PM
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Will be pulling a beat to **** 00' t56 apart soon that has 92k miles on it, and i'm dieing to see how many fork pads are still good. Along with what ever else is fukd. But keep up the posts on what everyone has expierenced with this, since a lot of us are wondering if the bronze pads/billit keys are needed.
06-06-2010, 03:00 PM
#11
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Here's my view on this subject.
I have built well over 1000 T56s myself (no exaggeration) in the last 6 years. My first impression was that every T56 needed the bronze pads. I used to believe in them, but not so much now.
First, make a note of this.. The stock fork pads ere engineered to be able to glide in the groove in the sleeve. They are composed of a synthetic nylon, not just a generic "plastic". The sleeves on all synchro assemblies are constantly turning any time the car is running. I would say that 80-90% of the T56s that I've rebuilt have 75k-125k miles and have never been opened up. Sure I have found broken and brittle pads. A small percentage of these T56s have had the pads destroyed to the point that they have fallen out of place, causing damage to the shift fork. This is after a LOT of miles as well as years and years of use and abuse, of course. However, the majority (60-65%) of the T56s that I've opened up had minimal to average wear on the fork pads.
Bronze fork pads are completely different, as its a soft metal. A soft metal, which rides in a groove in the sleeve, which is hardened steel. It does not have the ability to glide and resist wear, since its a soft metal riding on a hard metal. Instead, the sleeve wears into the pad much quicker than it would with the stock pads. Granted, the bronze is much more solid than the nylon, its not really doing much good.
I've gone back through three different T56s that had bronze pads, and found that the side walls were worn through anywhere from 30-60%. One of these trannys only had 5000 miles since the initial rebuild & the pads were worn 50% through. This causes there to be extra play between the fork and slider, which would make the shifts a little sloppy. I will post pics of them as soon as I get a chance. I'll do my best to bring my camera to the shop Monday and get them posted Monday night.
So, my final conclusion is that there are pros and cons with both types of fork pads, so it's not really worth spending the ~70 bucks on the bronze ones. Plus I really don't like the idea that there is more play in the trans with the bronze pads, so that is why I don't recommend them. However, I do keep them in stock for anyone who requests them.
Any time I run into things like this, I do my best to design something better. So, it looks like I have yet another project in the works.
I'm thinking a superior nylon-type material (non-metal), thats much better than the stock pads. Looks like I have some homework to do! Luckily I have access to 4 unique top-notch machine shops, so I do all the engineering, and have them do the production.
-Jason
I have built well over 1000 T56s myself (no exaggeration) in the last 6 years. My first impression was that every T56 needed the bronze pads. I used to believe in them, but not so much now.
First, make a note of this.. The stock fork pads ere engineered to be able to glide in the groove in the sleeve. They are composed of a synthetic nylon, not just a generic "plastic". The sleeves on all synchro assemblies are constantly turning any time the car is running. I would say that 80-90% of the T56s that I've rebuilt have 75k-125k miles and have never been opened up. Sure I have found broken and brittle pads. A small percentage of these T56s have had the pads destroyed to the point that they have fallen out of place, causing damage to the shift fork. This is after a LOT of miles as well as years and years of use and abuse, of course. However, the majority (60-65%) of the T56s that I've opened up had minimal to average wear on the fork pads.
Bronze fork pads are completely different, as its a soft metal. A soft metal, which rides in a groove in the sleeve, which is hardened steel. It does not have the ability to glide and resist wear, since its a soft metal riding on a hard metal. Instead, the sleeve wears into the pad much quicker than it would with the stock pads. Granted, the bronze is much more solid than the nylon, its not really doing much good.
I've gone back through three different T56s that had bronze pads, and found that the side walls were worn through anywhere from 30-60%. One of these trannys only had 5000 miles since the initial rebuild & the pads were worn 50% through. This causes there to be extra play between the fork and slider, which would make the shifts a little sloppy. I will post pics of them as soon as I get a chance. I'll do my best to bring my camera to the shop Monday and get them posted Monday night.
So, my final conclusion is that there are pros and cons with both types of fork pads, so it's not really worth spending the ~70 bucks on the bronze ones. Plus I really don't like the idea that there is more play in the trans with the bronze pads, so that is why I don't recommend them. However, I do keep them in stock for anyone who requests them.
Any time I run into things like this, I do my best to design something better. So, it looks like I have yet another project in the works.
I'm thinking a superior nylon-type material (non-metal), thats much better than the stock pads. Looks like I have some homework to do! Luckily I have access to 4 unique top-notch machine shops, so I do all the engineering, and have them do the production.
-Jason
06-06-2010, 05:17 PM
#12
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About 90% of the T56's I open up have broken fork pads. That being said, I'm partial to bronze fork pads. All else being equal, I would prefer bronze over plastic anyday.
06-06-2010, 07:03 PM
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Here's my view on this subject.
I have built well over 1000 T56s myself (no exaggeration) in the last 6 years. My first impression was that every T56 needed the bronze pads. I used to believe in them, but not so much now.
First, make a note of this.. The stock fork pads ere engineered to be able to glide in the groove in the sleeve. They are composed of a synthetic nylon, not just a generic "plastic". The sleeves on all synchro assemblies are constantly turning any time the car is running. I would say that 80-90% of the T56s that I've rebuilt have 75k-125k miles and have never been opened up. Sure I have found broken and brittle pads. A small percentage of these T56s have had the pads destroyed to the point that they have fallen out of place, causing damage to the shift fork. This is after a LOT of miles as well as years and years of use and abuse, of course. However, the majority (60-65%) of the T56s that I've opened up had minimal to average wear on the fork pads.
Bronze fork pads are completely different, as its a soft metal. A soft metal, which rides in a groove in the sleeve, which is hardened steel. It does not have the ability to glide and resist wear, since its a soft metal riding on a hard metal. Instead, the sleeve wears into the pad much quicker than it would with the stock pads. Granted, the bronze is much more solid than the nylon, its not really doing much good.
I've gone back through three different T56s that had bronze pads, and found that the side walls were worn through anywhere from 30-60%. One of these trannys only had 5000 miles since the initial rebuild & the pads were worn 50% through. This causes there to be extra play between the fork and slider, which would make the shifts a little sloppy. I will post pics of them as soon as I get a chance. I'll do my best to bring my camera to the shop Monday and get them posted Monday night.
So, my final conclusion is that there are pros and cons with both types of fork pads, so it's not really worth spending the ~70 bucks on the bronze ones. Plus I really don't like the idea that there is more play in the trans with the bronze pads, so that is why I don't recommend them. However, I do keep them in stock for anyone who requests them.
Any time I run into things like this, I do my best to design something better. So, it looks like I have yet another project in the works.
I'm thinking a superior nylon-type material (non-metal), thats much better than the stock pads. Looks like I have some homework to do! Luckily I have access to 4 unique top-notch machine shops, so I do all the engineering, and have them do the production.
-Jason
I have built well over 1000 T56s myself (no exaggeration) in the last 6 years. My first impression was that every T56 needed the bronze pads. I used to believe in them, but not so much now.
First, make a note of this.. The stock fork pads ere engineered to be able to glide in the groove in the sleeve. They are composed of a synthetic nylon, not just a generic "plastic". The sleeves on all synchro assemblies are constantly turning any time the car is running. I would say that 80-90% of the T56s that I've rebuilt have 75k-125k miles and have never been opened up. Sure I have found broken and brittle pads. A small percentage of these T56s have had the pads destroyed to the point that they have fallen out of place, causing damage to the shift fork. This is after a LOT of miles as well as years and years of use and abuse, of course. However, the majority (60-65%) of the T56s that I've opened up had minimal to average wear on the fork pads.
Bronze fork pads are completely different, as its a soft metal. A soft metal, which rides in a groove in the sleeve, which is hardened steel. It does not have the ability to glide and resist wear, since its a soft metal riding on a hard metal. Instead, the sleeve wears into the pad much quicker than it would with the stock pads. Granted, the bronze is much more solid than the nylon, its not really doing much good.
I've gone back through three different T56s that had bronze pads, and found that the side walls were worn through anywhere from 30-60%. One of these trannys only had 5000 miles since the initial rebuild & the pads were worn 50% through. This causes there to be extra play between the fork and slider, which would make the shifts a little sloppy. I will post pics of them as soon as I get a chance. I'll do my best to bring my camera to the shop Monday and get them posted Monday night.
So, my final conclusion is that there are pros and cons with both types of fork pads, so it's not really worth spending the ~70 bucks on the bronze ones. Plus I really don't like the idea that there is more play in the trans with the bronze pads, so that is why I don't recommend them. However, I do keep them in stock for anyone who requests them.
Any time I run into things like this, I do my best to design something better. So, it looks like I have yet another project in the works.
I'm thinking a superior nylon-type material (non-metal), thats much better than the stock pads. Looks like I have some homework to do! Luckily I have access to 4 unique top-notch machine shops, so I do all the engineering, and have them do the production.
-Jason
If so, give me a pm and I can put you in contact with a Corvetteforum member who is an engineer and works with plastics. He really knows his stuff and might prove helpful.
06-06-2010, 07:45 PM
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Yeah when I get my tranny rebuilt I want it to last as long if not longer then when it was stock.... I do want it to shift really nice too, but I like to drive my car, it's not a race car.
06-07-2010, 02:09 PM
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Very interesting. Any consideration being given to Delrin? I'm no expert but it seems like an interesting material to explore as far as resistance to lubricants, lubricity, hardness, machineability, molding, etc.
If so, give me a pm and I can put you in contact with a Corvetteforum member who is an engineer and works with plastics. He really knows his stuff and might prove helpful.
If so, give me a pm and I can put you in contact with a Corvetteforum member who is an engineer and works with plastics. He really knows his stuff and might prove helpful.
06-07-2010, 02:34 PM
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I think all the factory pieces are the same Nylon material. Not sure which nylon though. There's more than one "nylon".
06-07-2010, 07:33 PM
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If you look closely at the stock plastic fork pads, it looks like it was made using injection molding process. The inside of the pads have a little pins that fit onto the holes on the fork. I don't know if that could be made using CNC machine.
06-07-2010, 09:14 PM
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Wouldn't be any more difficult than CNCing bronze pads like they do now. Besides, are the little pins necessary during operation or are they there just hold the pads in place during assembly?