T-20 Troubles--Which One to Rebuild???

[Rolling_X_6]

I need some advice on my T-20 tranny situation.

Some quick background (or as quick as possible): I bought this 2000 Max IV back in October, 2009. It was supposed to be in great working order, so I paid around $4,500.00 for it. But, it turns out I took a beating on this machine, only the 25 HP Kohler works well on it.

I spent every available evening and weekend for three weeks and over $500.00 ripping the engine and tranny out and fixing and replacing various aspects of the drive train: chains, sprockets, bearings, etc. Finally, I got it all fixed up . . . I thought . . . and put it all back together. I took it for a test drive or two, and then the T-20, itself, went out on it . . . stranding me a couple miles from home. (Something happened to the left side wherein it wouldn’t brake going forward and wouldn’t drive in reverse: bands, I guess.)

So, I ripped the engine and tranny out again. Fortunately, my brother had two, old T-20’s from an old Chaparral that he had. The one worked great the last he used it, and the other had a frozen diamond, forward/reverse shifter on the right side. So, we decided that I would just rob that old, working T-20 out of his Chaparral, as his machine did not work right now, anyhow. I had to do some modifications, as this older T-20 had the eye-bolt style steering linkage. Then, I put it all together, but I noticed a minor problem during my first test drive. The secondary, driven clutch would open up and hit the chain at high-end.

So, I ripping the engine and tranny out AGAIN and then installed the two spacer washers that were on my original T-20 onto this replacement T-20 to shim the secondary, driven clutch out away from the chain. I put all back together AGAIN!!! (This is now four months since I bought this Max IV and the third go round of ripping the engine and tranny out and making repairs and then reinstalling everything . . . and all before I took a single pleasure ride or even used an 1/8 tank of gas.)

After getting everything back together this third time, I took it for a test ride. At first, it worked great. But, when I went to put it into reverse to back it into my garage and declare this all FINALLY to be a success . . . this second T-20 went out on me!!! Oh yes . . . I AM serious!!! It wouldn’t go into reverse, and then something jammed so that I also couldn’t get it into forward, either. It was something with the diamond, forward/reverse shifter on the right side . . . just like my brother’s other old T-20 had wrong with it.

DING . . . DING . . . DING . . . NOW ROUND FOUR!!!

That is where I am, now. I have the engine and tranny ripped out for the fourth time . . . which brings me to the point of this email:

What do you folks think I should do now??? Obviously, I need to tear apart and rebuild one of these T-20’s. But, I am not sure if I should rebuild the original, newer T-20 or the older T-20 that has been modified for my purposes. Are the newer ones better in some way??? Are the parts NOT available from Recreatives for the older ones??? If either of these is the case, I will rebuild the newer one, but otherwise, I am leaning towards rebuilding the older T-20, as I like that eye-bolt style of linkage better . . . plus, I have two of those older T-20’s, so maybe I could do some mixing and matching with those two older T-20’s. On that note, are the internal parts of the various models of T-20’s different??? Or, are the gears and bands and so on the same across the years???

Sorry for the long post, but I felt that for you to be able to help me best, you would need this background.

Thanks in advance for any help you can offer me.

[racerone3]

if it were me, i would rebuild the one out of the Chap that you have already modified to fit your machine. the older ones have a "supported main shaft" (bushing on the right side of the trany to hold the end of the input shaft) and are supposed to be stronger. you might also spend a day tearing down all three. you might find that there are only minor issues with the ones that aren't shifting (the other one probably has a broken band). once you have them all apart you can clean and inspect all three and decide which is the best canidate for a rebuild. #30 O-rings from the plumbing section at the hardware store will replace your plunger o rings and you can use black high temp silicone to seal the case havles back together instead of gaskets

[Rolling_X_6]

Thanks for your help, racerone3.

I have decided to go with the T-20 that I modified from the chaparral, as you have suggested, racerone3. I just prefer the tightness of the old, eye-bolt style steering linkage. Plus, the newer T-20 had a few minor defects as the result of trying to fix up the major problems that this machine had when I first bought it back in October. I mean, there is nothing WRONG with it, but if I can avoid going with that tranny housing when rebuilding, I am going to. And, the other older T-20 from the other Chaparral has some minor issues, as well.

I am considering tearing apart the other two T-20's to see if I can get any parts from them.

Are the internal parts of the various models of T-20 mostly the same, like the bands, plungers, and so on???

Thanks.

[racerone3]

the biggest differences i've seen in t-20s (other than the main shaft) is in thrust washers. the trans in my racer didn't have any, my spare trans has thrust washers on either side of the sun gears... also the newer plungers have 2 o-ring groves in them. old plungers can be taken to a machine shop and have a second grove cut in them

[Rolling_X_6]

the biggest differences i've seen in t-20s (other than the main shaft) is in thrust washers. the trans in my racer didn't have any, my spare trans has thrust washers on either side of the sun gears... also the newer plungers have 2 o-ring groves in them. old plungers can be taken to a machine shop and have a second grove cut in them

Thanks for your continued help, racerone3. I appreciate it. I can tell you know your stuff. At least, what you say sure is holding true with what I am seeing.

For example, it is funny you mention that about the thrust washers . . . when I tore the first half apart, this T-20 did not have any thrust washers, either. I was even going to mentioned that in my last post. And to further add to that . . . the guy who my brother bought his Chaparral off of used it for racing. That is weird. You sure do know your stuff.

I guess I should add thrust washers to this T-20 when I put it back together so that it is more stock. Besides, I will not be racing with it. Hee Hee!!!

And yes . . . I did notice that this T-20 does have the plungers with only one o-ring grove. Could I just swap the plungers from my newer T-20 that probably has the plungers with the two o-ring groves???

[6X6]

I'll add one more difference. I noticed between new style (in my wolf) and old (in my Colt and spare tranny I found) The shift drum that engages the drum for either forward or reverse has more teeth (and so do the drums) in the old style. I don't remember the count off-hand, but if memory serves me, it's double on the old style, and there just spaced farther apart on the new style, not larger. This is why I wanted an old style for my racer, well that and that supported shaft Racer mentioned.

OH: Yes, you can interchange plungers from the new to the old. But you only really have to worry about the bottom, the tops don't leak out fluid, the O-ring will just keep out the dirt so a double seal is not needed.

[mark m.]

I guess I should add thrust washers to this T-20 when I put it back together so that it is more stock. Besides, I will not be racing with it. Hee Hee!!!

I do believe you cannot add the thrust washers to to the older transmission. At first glance the older and the newer components look the same but the newer ones are machined slightly different to accommodate the clearance needed for the thrust washers. In other words, the older trans will not bolt back together with the new washers. It can be done but you would need to machine the related parts.

I updated an older style transmission to use the thrust washers some years ago for my Starcraft but I did not record the changes to the components.

[Rolling_X_6]

That's all great info. It is stuff that I would not have known without the forum and you folks. Thanks.

So, does that mean I should just forget about thrust washers??? Should I just assume that since this model of T-20 was not designed for them that it is okay without them???

In the case of these older T-20's . . . do they work just as well without thrust washers (seeing as how they were not designed for them) as the newer T-20's do WITH thrust washers???

Does anyone else have any experience with or thought about this topic??? It would be appreciated.

[mark m.]

If I were you I would first tear down both the old and the new being careful not to mix the parts.
Next, take an assessment as to the condition of each set of parts. Lets assume the older trans will most likely have more hours on it because of it's age. Look for signs of unusual wear or better said, severe wear. Only then can you make a determination as to how much expense your willing spend.

There is nothing wrong with using the earlier style trans if you find that the parts are in fact in better condition than the later style one. The thrust washers were used to eliminate metal to metal contact.
Realy not much thrusting going on there just a seperation.

I don't believe you can buy pre-thrust washer parts for the older one so thats another decision you have to make but to make sure you can always contact the factory for availibility.

Hope this helps.....keep us posted.

Mark

[Rolling_X_6]

I ripped apart all three of my T-20 trannys, and here’s what I found:

Tranny #1 is the one older T-20, the one I was hoping to be able to fix up to use. This is the one that--all of the sudden--wouldn’t go into reverse on the left side, the input side. The diamond shifter wouldn’t move. It turns out that the little shifter pin that sticks out of the bottom of the vertical shaft attached to the diamond shifter was ripped out of the side of that vertical shaft. But, at some point in the process, the side of the grove in the shift collar that the little shifter pin travels in also got broken. So, now that shift collar down inside of the T-20 is also junk. So, I decided to rip Tranny #2 apart to see if I could rob some parts from that one to get Tranny #1 up and running.

Tranny #2 is the other older T-20, the one that was locked up. I quickly learned why it was all locked up. For some reason, there was no oil whatsoever in it, and it was all rusted tight. I fought to be able to get any of it apart. And, when I did get some of it apart, I saw that many of the parts were different from Tranny #1, at least all of the ones I needed to fix up Tranny #1 were different.

So, I moved onto Tranny #3, the newer, original T-20 that came with my 2000 Max IV. The only functional thing wrong with this tranny, as far as I knew, was the one band on the right side was broken, as it wouldn’t brake forward or drive in reverse on the right side. So, I got it apart, and I found that the band did not BRAKE, per say. The steel part of the band was still intact, but the lining on the one band had fallen off and broken. This was not, in itself, a big surprise, as I suspected I would need new bands to fix Tranny #3. But, the problem is that in the process of the lining falling off, the one drum got ruined. So, now it needs new bands and a new drum. But, I cannot just take parts from Tranny #1 to fix up Tranny #3--or vise versa--because the parts are not interchangeable between the two. Yes . . . I have three T-20’s, and all three have distinct part, one from another . . . no two alike. I don’t know if that is typical or not. But, I am considering it to be “par for the course” for me right now as it pertains to my 6X6.

Any thoughts on how I should proceed right now???

I am assuming I will need to rebuild Tranny #3, as that is the only one I can still get parts for. I guess if I buy that one drum and a set of bands, I will have all that I need . . . I am still not sure about the bearings in Tranny #3. But, I guess that’s another story.

Any help or thoughts would be appreciated.

[6X6]

Ouch, thats rough. Parts for the older T-20 are available, some you'll need to get used but speak with someone at Recreative Industries, they can tell you what new parts will fit the old style tranny (Probably close to all) some may require changing a few parts but I'm no expert on that, I've never tried combining two different styles of T-20. The rusted solid T-20 will be pricey to fix. You could maybe start soaking it in ATF and see how bad it is, If the drum surfaces are badly pitted, and/or bearing surfaces are, it's not gonna have much usable parts. The other old T-20 MAY be your best bet. The diamond shifter from a new T-20 should drop right in, no differenced as far as I know (Someone confirm?)
The shift collar on a new one I THINK has 1/2 the # of teeth to engage, but you may be able to salvage one from the rusty T-20, if it's not more than minor surface rust on it, or get a new one from Recreative Industries. Drums are pricey, once a band wears into one, it's done, and not a cheap fix.
I'd personally look over the better old style good, and if you only need the shifter and shift collar, bands/drums look good, I'd bank on that being your best bet. (In the new tranny, if one band lining flaked off Chances are the other bands are either worn pretty good, or moisture and/or Gear oil got in the tranny and they too will start coming off soon)

[Mike]

On #3 are the other 3 bands in bad shape? If not you can just replace the one that failed. Sometimes the lining on one band comes off and the others are fine. That happened to the T20 in my Max. I replaced one band and one drum about 5 years ago and it has been fine ever since. While you have everything apart I would check the bearings real closely and maybe even just go ahead and change them and the seals too. That's a little more $$$ since you have to get the bearings from Recreatives but it is well worth not having to pull the tranny back out in a year to replace the bearings because you have to take EVERYTHING apart to change replace them. Just some ideas.

[Rolling_X_6]

The diamond shifter from a new T-20 should drop right in, no differenced as far as I know (Someone confirm?)
The shift collar on a new one I THINK has 1/2 the # of teeth to engage, but you may be able to salvage one from the rusty T-20, if it's not more than minor surface rust on it, or get a new one from Recreative Industries.

Thanks, John, for your feedback.

I am quickly learning that there are many variation between the various years of T-20's. I have three T-20's laying here apart, and all three have different shifter setups; none of them are interchangeable. All of the shifter collars that I have here have the same number of teeth on them (18), but they are shaped differently. The two older shift collars have sort of skinny, round (hexagonal) teeth. The newer shift collar's teeth are more elongated and therefore beefier. They might work interchangeably; I am not sure. But, they are clearly different.

Plus, there is a difference between the various diamond shifter levers. The vertical shafts that are attached to the diamond shifters are all the same size, I think. But, some of those little, actual shifting pins that stick out the bottom of those vertical shafts are different sizes, different thicknesses. Therefore, the interal shift collars need to match up with these various shift pins. My Tranny #2 has smaller shift pins, and therefore it has shift collars with smaller grooves. So, those parts are not interchangeable.

As far as fixing up Tranny #2, I would not be able to do that. That's for sure!!! It is rusted pretty badly. Some of the parts could be reused, but not all of them. The hardest part would be getting it apart to even be able to use them.

I am thinking that unless I could get some parts from a member on the forum, here . . . or maybe from Richard's Relics or something, I am going to have to fix up the newer one. At least then, I can get the parts I need. I talked to someone at Recreatives, and they do not sell any parts for the older model T-20's. And, they were not sure how well some of those parts would match up . . . new on an older T-20.

Thanks again, John.

On #3 are the other 3 bands in bad shape? If not you can just replace the one that failed. Sometimes the lining on one band comes off and the others are fine. That happened to the T20 in my Max. I replaced one band and one drum about 5 years ago and it has been fine ever since. While you have everything apart I would check the bearings real closely and maybe even just go ahead and change them and the seals too. That's a little more $$$ since you have to get the bearings from Recreatives but it is well worth not having to pull the tranny back out in a year to replace the bearings because you have to take EVERYTHING apart to change replace them. Just some ideas.

Thanks for the reply, Mike.

The bearings SEEM fine in both Trannys #1 and #3. I cannot get Tranny #2 apart enough to even tell. But, I think I am all right in that regard.

I was thinking about doing what you said and just replacing the one band and the one band. I am not sure yet . . . I was also thinking about using the bands out of Tranny #1, as they seem good and none of them failed. I have also considered replacing all four of them with new for the same reason that you mentioned replacing the bearings while it is all apart.

I am thinking in twenty different directions. My head is just spinning with all of this.

[6X6]

. All of the shifter collars that I have here have the same number of teeth on them (18), but they are shaped differently. The two older shift collars have sort of skinny, round (hexagonal) teeth. The newer shift collar's teeth are more elongated and therefore beefier. They might work interchangeably; I am not sure. But, they are clearly different.

I'm wondering if there is more than two variations on these collars now. I will have to check next time I have the Wolf's tranny apart. Wait, I actually hope I don't have to do that any time soon

Plus, there is a difference between the various diamond shifter levers. The vertical shafts that are attached to the diamond shifters are all the same size, I think. But, some of those little, actual shifting pins that stick out the bottom of those vertical shafts are different sizes, different thicknesses. Therefore, the interal shift collars need to match up with these various shift pins. My Tranny #2 has smaller shift pins, and therefore it has shift collars with smaller grooves. So, those parts are not interchangeable.

I'm learning more from this thread by the minute. I broke a shift pin (old T style pin, and just ordered new pins from Recreatives. They never asked which T-20 version or measurements, they just sent 'em. They press fit right in and work fine, they're just a hardened roller bearing instead of a T shaped pin. That's good to know (Although bad news). by chance did you measure the grove in the shift drum and see it is in fact narrower, not just a narrower pin? (You've really got me curious now since I have 2 old style trannys, and need to know what to tool up for and make spares of while apart.

I talked to someone at Recreatives, and they do not sell any parts for the older model T-20's. And, they were not sure how well some of those parts would match up . . . new on an older T-20.

Well you can Mic and/or test fit a lot of the stuff, even if it's damaged. If those shift teeth are compatible, I'd mic. up the rest of the drum new damaged one and a good old one to see if they are compatible (Or make friends with a machinist ) If you can use one of yours that will save you a bit of $$$ Good luck, hope to hear of some progress soon

[Rolling_X_6]

I'm wondering if there is more than two variations on these collars now. I will have to check next time I have the Wolf's tranny apart. Wait, I actually hope I don't have to do that any time soon

I don't know. But, I would guess that any of the newer models--any with the C-channel style steering linkage--will all be the same. I have no idea how long they have been making them that way . . . over 20 years??? But, I would say if they have the older style steering linkage, it is hit and miss.

I'm learning more from this thread by the minute. I broke a shift pin (old T style pin, and just ordered new pins from Recreatives. They never asked which T-20 version or measurements, they just sent 'em. They press fit right in and work fine, they're just a hardened roller bearing instead of a T shaped pin. That's good to know (Although bad news). by chance did you measure the grove in the shift drum and see it is in fact narrower, not just a narrower pin? (You've really got me curious now since I have 2 old style trannys, and need to know what to tool up for and make spares of while apart.

Yeah . . . the groove in the shift collar is correspondingly narrower to go along with the smaller diameter pin. (It would have to be, or there would be a lot of "play" in the shifters to get it in/out of forward/reverse.) As I explained, that shift collar is one of those rusted-together parts I needed from Tranny #2 to fix up Tranny#1. So, I was checking that out closely. Just to confirm it, in fact, I tried inserting a right side diamond shifter from Tranny #3 down into that shaft on Tranny #2, and it would only go in so far . . . only until the larger shift pin from Tranny #3 tried but could not fit into the narrower groove of Tranny #2's shift collar. Tranny #1 and #3 are the larger ones. Only Tranny #2 is the smaller one.

It would be easy to check, if you're curious. Just pull one of your diamond shifters out of your various T-20's and compare. You will quickly see if any of them are different. I would bet there are only two sizes out there, and I would bet the smaller ones are the real old ones, or something. Further, those two pin styles are significantly different. You can see the difference with your naked eye. You will not need to mic them or anything.

Well you can Mic and/or test fit a lot of the stuff, even if it's damaged. If those shift teeth are compatible, I'd mic. up the rest of the drum new damaged one and a good old one to see if they are compatible (Or make friends with a machinist ) If you can use one of yours that will save you a bit of $$$ Good luck, hope to hear of some progress soon

I would not doubt that a drum would be compatible from Tranny #1 to fix up Tranny #3, except that Tranny #1 was not made for trust washers (neither was Tranny #2). But, Tranny #3 was made for thrust washers. I am not sure what all would need to get cut down--or how much--to make this work . . . if I would to go that route.

I am gaining way too much experience--way too fast--for my liking (baptism by fire, here), but nevertheless, I do not feel confident enough to take some pieces and head off to the local machine shop. And, then come home and start putting Tranny #3 together. I would not feel confident that I have the right stuff done to make it work its best.

I don't know . . . I will have to think about it.

Thanks for the continued help, John.