TFS355S10

I'm going to be rebuilding my T56 this fall probably. Just looking for recommendations as to what parts to upgrade while it's apart.
A steel 3/4 shift fork seems to be a common upgrade, so I'll plan on that. What about the shift fork cushions? Stock nylon or bronze? Any common bearing weaknesses?

Macs98Z

iTrader: (16)

Others will chime in I'm sure, but I would do the steel 3-4 shift fork and bronze pads, personally. I've heard some debate the bronze vs. nylon, but I like my bronze ones so far. Nylon seems prone to breaking too much for my liking. I would also replace all the blocker rings with carbon fiber replacement rings. I think almost any rebuild kit with blocker rings are carbon fiber. Billet shift keys are a good idea too, along with upgraded springs for the synchros.

As for other upgrades, it will really depend on what the trans needs when you open it up and look at it. Do yourself a favor and hold off on ordering parts until after you have it apart. A lot of the time there will be stuff you thought you didn't need that you do, and vice versa. It will save time and money doing it this way. Bearings are usually good for the life of the trans if well taken care of. Visually inspect all bearing surfaces for pitting/galling or any other signs the bearing is bad. If you don't have any problems, don't bother replacing them. It will make the rebuild a lot easier if you don't have to reset clearances too.

brigade24

depending on the year of the car, if it came with the paper-lined blocker rings..i would switch those to carbon rings. then you're not married to dexIII trans fluid.

i used nylon pads because i didn't want the bronze to carve into the sychro hub assembly since i do race the car. bronze pads however, will def last longer...

3-4 steel fork has already been mentioned.

the tip of your input shaft rides inside a pilot bearing...i would switch the bearing for a bushing. over time the rollers inside the bearing will come loose and scratch the tip of the input shaft which is substantially more expensive to replace. keep in mind, the bushing may not last as long as the bearing but it will not harm your input shaft.

hope this helps.

Macs98Z

iTrader: (16)

Thank you for mentioning this. I've never heard anyone talk here about the real longevity disadvantages on the bushings. Consequently, I tried a bushing because of the fears I had about a bearing chewing up my input shaft, but the bushing only lasted about 8K miles. I put in a bearing after that because I have a street driven car, not a track car. Talked to Steve @ Monster about this and he never recommends street cars to run bushings for this reason. He said most only last around 10K miles or so because they don't support the input like a bearing does.

OP, depending on your needs, take the previous post and this one into consideration for bearing vs. bushing. A bearing can damage the input, but cases I know of where the bearing went bad, it made noises before destroying the input so you should have warning before anything would happen.

TFS355S10

Thanks for the info guys. I'll take it all into consideration for sure.

I should have the steel 3/4 fork at home when I get there. I'm always wondering about the bushing/bearing thing. The bushings were standard equipment for a lot of years and ran a lot of miles. But the bearing seems like a good idea. I'm running a bearing as of now so I'll probably stay with that if all seems well when I take the trans out next time.

The trans I'll be working on has been rebuilt at some point in the past because it has a rebuilt tag on it. It shifted great and was in 100% condition until I lost a drive shaft and broke the bellhousing. I drove it about 400 miles to get home before I discovered for sure what the problem was, (broken bellhousing), but by then the pilot bearing had chewed up the input shaft and the throw out bearing snout was broke off. I can't blame the bearing for the input shaft damage though since the trans was basically hanging on the input shaft for that drive home. lol

For this one I think I'll stay basically stock, (steel 3/4 shift fork and replace the input shaft, front plate). I'll check everything else to make sure there's no other damage while I'm in there.

More questions;
1. Since it has been rebuilt in the past, what's the likelihood of it having the carbon blockers in it already?
2. How can I tell the paper lined blockers from the carbon ones?
3. If not Dexron III is there a more preferred lube?
4.One vote each way for shift fork pads. Anybody else? lol Will the bronze pads actually wear into the syncro hub? I don't want that, but I've already had to replace the nylon pads on the reverse fork in my other t56, so I'm kinda leaning toward the bronze pads.

This is just a mild motored daily driver, but it will see quite a few miles. City, highway, and 400-700 mile trips about every 2-3 weeks.

TFS355S10

Thanks for the info guys. I'll take it all into consideration for sure.

I should have the steel 3/4 fork at home when I get there. I'm always wondering about the bushing/bearing thing. The bushings were standard equipment for a lot of years and ran a lot of miles. But the bearing seems like a good idea. I'm running a bearing as of now so I'll probably stay with that if all seems well when I take the trans out next time.

The trans I'll be working on has been rebuilt at some point in the past because it has a rebuilt tag on it. It shifted great and was in 100% condition until I lost a drive shaft and broke the bellhousing. I drove it about 400 miles to get home before I discovered for sure what the problem was, (broken bellhousing), but by then the pilot bearing had chewed up the input shaft and the throw out bearing snout was broke off. I can't blame the bearing for the input shaft damage though since the trans was basically hanging on the input shaft for that drive home. lol

For this one I think I'll stay basically stock, (steel 3/4 shift fork and replace the input shaft, front plate). I'll check everything else to make sure there's no other damage while I'm in there.

More questions;
1. Since it has been rebuilt in the past, what's the likelihood of it having the carbon blockers in it already?
2. How can I tell the paper lined blockers from the carbon ones?
3. If not Dexron III is there a more preferred lube?
4.One vote each way for shift fork pads. Anybody else? lol Will the bronze pads actually wear into the syncro hub? I don't want that, but I've already had to replace the nylon pads on the reverse fork in my other t56, so I'm kinda leaning toward the bronze pads.

This is just a mild motored daily driver, but it will see quite a few miles. City, highway, and 400-700 mile trips about every 2-3 weeks.

superspirit

bronze is a lot softer than the steel the synchros are made of, I personally run them and like the firmness of the shifts. with proper lube I dont think they will create any excessive wear. but I just rebuilt mine and installed them so I have no long term evaluation of them.

Macs98Z

iTrader: (16)

1. No way to know except to look at them
2. I attached a pic comparing the two. Paper is in the foreground and CF is in the background.
3. You can also use Pennzoil Syncromesh; I run it and it has done well for me. From what I've heard, its the same as GMs Syncromesh.
4. I already voted

brigade24

no problem, if someone drives hard enough, a bushing will be toast in about 7k miles...i autox and hpde my car so it's more cost effective for me to pull the trans every season to change the bushing than to pull the trans every two seasons to replace a bearing and an input shaft...as you mentioned, street cars will most likely be better off running the bearing...so what Steve said is consistent with my personal experience.

stevieturbo

A pilot bush will never wear in 7k.

Cars were fitted with bushes for years and they lasted the life of the car.

The only time wear can actually occur is when there is a difference in rotating speed between crank and input shaft. And the only time that occurs is when your foot is on the clutch

Which really shouldnt be that often in relative terms.

I'd be shocked if the bush didnt last 70k.

brigade24

yes. you would be constantly shifting gears when racing...hence the 7k miles.

at the end of the season, i'll post a pic of the bushing in my car...it should have around 3100 miles on it and we will see what it looks like.

stevieturbo

Split second at a time, with minimal change in shaft speed vs crank speed during that time.

The input shaft doesnt come to a stop during a shift, it's speed just changes briefly.

As said, cars have used bushes for decades and they never wore out that quick.

Macs98Z

iTrader: (16)

Don't argue that with me. Take it up with Steve at SNL--that has been his experience with these cars as well as mine.

I understand what you're saying and recognize bushings were used for years in muscle cars. However, we are talking years ago and I wouldn't doubt if the composition of bronze bushings or trans input shafts has changed. Besides that, our cars were originally equipped with a pilot bearing. If the bushing worked so well for years, why did they change it? I would be willing to bet there was either an inherent durability issue between the bushing or the bearing or there was a materials change in the input shaft or composition of bushings that necessitated the switch to bearing use.

Just my theory, but the facts are that most bushings in LS cars don't last as long as bearings.

stevieturbo

And to add to that, unlike many older cars, the gearbox bearings and mainshaft in the T56 is pretty robust, the input shaft is held very securely.

Both of which mean less chance of wear or walk on the input shaft which might aggravate wear of any bushing.

It would be hard to argue that they selected a needle roller bearing for reliability, especially when it's a well documented fail item.
But then with newer models they did change to a proper bearing instead.

So really...the needle roller version really isnt a good item.

Macs98Z

iTrader: (16)

I don't know, man. I hear what you are saying...I'm just speaking from mine and other's personal experience. You can debate it if you want. Just trying to help the OP and others out.

BALLSS

my vote for a modern T56, use a bearing vs bushing. tremac specs it.

also steel 3-4 and billet keys. IIRC Tremac switched to carbon blockers mid 90's

Paper blockers did not like synthetics but carbon are OK with them.

Redline D4 is my vote if you feel Dex 3 is not what you want

brigade24

hmm...i would imagine that not a lot of wear would take place when the input shaft stops turning.

The wear obviously takes places when the input shaft is rotating...when shifting at high rpm, the shaft will carve a small groove into the bushing.

trust me, i want you to be right because it will save me time and money.

brigade24

the 1-2 billet keys can also be done. I read that the 3-4 sychro keys are the same ones as 5-6 sychro keys and reverse synchro keys...so all the keys can be upgraded but it certainly isn't necessary...the billet keys make shifting smoother

stevieturbo

Well if the engine is at 7000rpm and the input shaft is not turning, I rather suspect wear would occur at that point.
That's a 7000rpm difference in speeds

If the input shaft is rotating and the engine is rotating at the same or similar speeds...clearly that's a small difference, minimal wear will occur.

Pharcyde50

iTrader: (11)

Just rebuilt mine added:

Carbon Fiber blocker rings/syncros
Billet 1-6 keys
New 1-2 & 3-4 slider
Steel 3-4 Fork
Bronze Shifter Bushing
Bronze Fork Pads

Also had to replace 3rd gear and the input shaft

Reshimmed and ready to go