1989 Tucker 1644c

[Track Addict]

You get those at the local Tucker Parts Thrift store. Most recent part numbers to cross are 3303,4303, 5303, 7303, 9303 which are all the same part featured here it appears.

I also got roller guy. Love the recycling many many years later.

 

[1boringguy]

BFT,
You can see on the early grouser where it was doubled for a ways beyond the backside brace plate for added strength. And subsequent changes of lengthening the brace plate certainly looks to be stronger, however not nearly as serviceable without some creativity in dealing with broken/stripped bolts. I'm guessing the changes in the backing plate were to reduce belt cracking and possibly pulling the backing plate through the belt, but just a guess.

PP, TA,
I would think sprocket rollers would have to be hardened, and the length of these spacers would be critical so that it provides the proper grip of the belting without deforming it adversely. I'm curious now. Didn't hit one with a file but was short a couple, so when they get here I'll have to check with a file, let you know.

 

[1boringguy]

As BFT said, my rear 5th wheel plate was ugly, especially considering it's made of T1. There were undoubtedly several contributing factors, like spooled diff. and overloading. But have discovered a couple more, probably the major one.

The 5th wheel plate itself is warped front to rear, checked with a straight edge. Even though our doubler that we added to the cracked area around the bushing may have contributed, every indication is that it's been that way a while.

For lack of knowing better I didn't really notice when I took it apart, how much pressure the cap over the poly block was creating. I'm guessing this shim under the block was from the factory and was perhaps standard practice to shim slightly as needed to relieve pressure on the 5th wheel bushing and trunion interface due to warping of the plate.

At some point in the past I think this cat broke some part of the rear tie rod or tie rod end and let the rear plate over rotate. One corner of the cap over the block was slightly bent and one can see where the poly block had been cut into by the edge of the cap, indicating that the 5th wheel plate had over rotated. Other damage could have occurred in that same event, like more bend in the plate, as a non-factory brace has been welded to the underside of the plate near the tie rod hole.

When going back together with the trunion/5th wheel, with the trunion inserted into the 5th wheel bushing i couldn't lift the rear of the 5th wheel plate up to the poly block, it would just lift the entire frame off the stands. A sign the bushing rebuild is good though.

If a person imagines forcing the rear of the plate up to the block and bolting it there, then it's not to hard to imagine this kind of damage to the 5th at the bushing area.

Since I think the factory used a shim, and since I already have the work done to the 5th wheel plate and to bend it back to straight would pull the weld at the doubler, and thinking it would only minutely change and spring/diff angles, I just built a thicker plate to go under the cap and raise it to the point that there isn't any pressure being created at the trunion bushing interface.

Thoughts pros or cons here?

 

[Track Addict]

Looks like and East Coast Upgrade! My line would be "can you believe the factory but the cat together like this?"

As long as that block stays on your plate full turn it's a solution. As the rear pivot wears it would improve your situation but add stress until that point. It will also cause a strange wear pattern. This looks to relieve the stress and work with that you have. Maybe cut/grind that plate to match the curves/flow of the plate below for the picky eyes.

Other solution is to make a new table plate which is unattractive, or cut out and weld back the rear cup at and angle which is equally unattractive.

 

[Pontoon Princess]

you have found a good workable solution

I see the white paint shows grease really well

 

[Mill666er]

My 1981 542 also had a shim but had a bronze sliding block. The block was warn and you can see where the jam nuts were digging into the shim. my 5th wheel pivot mounts extended all of the way out to the frame which probably helped with some of the stresses from pivoting. I had to bore out the cup and press in a bronze bushing and drop in an 1/8” shim to prevent the 5th wheel from dragging on the turn table. I also flipped the bronze block over but now have a gap at the top of the block.

 

[1boringguy]

Thanks for the input everyone. I'm going to try this anyway.

TA, I did make the shim plate 1" longer on each side than the original shim. I think that will keep the block riding entirely on the shim. I thought about the bushing being welded into the plate at a wrong angle, but then I checked the plate with a straight edge and the problem is with the plate.

M666r, yea mine has a gap at the top of the block too. I have a new poly block as well, just used that one to show the cut. The key is not creating pressure at the trunion/5th wheel connection with the weight on it, I think.

PP, yea white's definitely going to show the dirt ? Thats why I bought some white lubriplate low temp grease ?

 

[Blackfoot Tucker]

1BG,

In photo seven in post 123 it looks like a stack of flat washers are being used to space the poly block back along what I'll call the trunnion shaft. I don't know if it was a factory design change, or a previous owner lost the original part and came up with the washers, but on my machines Tucker used a single part that is essentially a machined sleeve as a spacer. I don't have one in front of me to measure, but as I recall the sleeve is about 1 1/8" long and the poly block rides deep in the bolt on channel segment. My impression from the photos is the washers are not as long as the machined sleeve...

Nice work!

 

[1boringguy]

BFT,
Yes they are washers. The ID of the washers are larger than the shaft as well. Since this is a block with the smaller diameter hole in the center, I just assumed Tucker perhaps simply used this as the same washer for smaller or larger sized shaft as needed. I didn't think much about the end clearance between the poly block and the hold down cap, I'll have to check it. And I'll check to see what I can find out from Tucker about a spacer instead of washers. Thanks for the heads up.

 

[Track Addict]

Any space between the faces of the poly block and retainer willl allow the trunion to side back and forth the same amount in the tube of the frame trunion holder.

As the thrust surfaces wear on the trunion holder/frameshims/washers get added to make up the slop.

Millers setup above seems improved where I assume you turn the nuts to take up the wear.

 

[1boringguy]

TA,
The trunion on my has the same sort of design. There is a nut, then a lock ring, and then another nut. You can see these pieces in this photo. The nuts are the sort that tighten with a spanner socket, and that then locks the end play you have set for the trunion. Seems the washers are just determining where the poly block is riding.

 

[1boringguy]

Just passing this along as information. The stock cam hold plate on my 360 is dead the same thickness as the shoulder on the cam, making for zero end play of the cam. Should be 5-9 thousandths. Am told there aren't various thickness plates made, so can have the plate plained down or some guys just use a grinder until you get the right amount of end play. I laughed, not a chance in hell my engine builder is going to be ok with having at it with a grinder. ?

Also have had to admit the obvious now, not a chance in hell this thing is going to be ready for SV either ☹

 

[olympicorange]

1bg, the area you need to ''reduce'' is a small diameter in comparison to the rest of the plate. a bridgeport would make short work of that. as long as the cam gear doesnt have any other interference issues with plate, bolts, etc. should be good to go,...

 

[1boringguy]

Slowly but surely. Push rods suppose to be here next week, but one has to take what suppliers and shippers promise with a whole bag of salt these days.

 

[1boringguy]

We have a heart beat.

At least 3 or 4 times Frank, my dyno expert, comments about how impressed he was with this fuel injection system. We'll see how it does out in the field, but I'm pretty happy with the preliminary indications.

The AF looks pretty good.

Carb and standard manifold can look as bad as this;

The curves, initial learning;

Numbers.

And the set up. Altitude about 2500 feet.

 

[DAVENET]

Torque everywhere there, eh?

 

[1boringguy]

DAVENET,

Again, it's hard to know where you have apples to apples when it comes to dyno numbers. You can see here we were straight out of long tube headers, no air cleaner, but spinning the mass of an old school 100 amp alt. I don't know anything about calibrating the dyno but I feel fairly confident we're in the ballpark though. Since Frank, a retired Micron engineer and rail car owner, isn't so much about bragging rights as just what's going on and how to improve on that.

The build goal was that torque of course. Thats a square engines forte, and it's easier to get dialed in and transfer to the field with the self learning efi I think, but yea I think it looks like we hit the target anyway. Hope I'm as happy with it on the snow.

 

[Blackfoot Tucker]

1BG,

Those are impressive numbers and I think validates your selection of components for the build. I noted the dyno sheet said "standard corrected power" which uses conversion factors for the differences in test conditions compared to standard day atmospheric pressure, temperature, humidity, etc. That takes some of the dyno BS out of the equation. I did see the alternator in the photo and a belt from the crankshaft powering the water pump and the alternator. My impression is that speaks to what you said about Frank; that he's not looking for bragging rights.

It seems just about every online or magazine article I've seen about an engine build will have a dyno photo showing no alternator and the water pump being driven by an external power source. Total BS, because that's not how the engine will be installed, and the water pump and alternator take significant power to drive them.

I must tell you, the Utah contingent (me, Mrs. Blackfoot and The Gorilla) thoroughly enjoyed meeting you, and your little boy, at SV 2021. Friday's snow cat trip was awesome, and you deserve a lot of credit for it. Fantastic memories!! I speak for all of us when I say we hope to see you next year at SV 2022!

 

[1boringguy]

BFT,

Thanks for the compliment, although the credit all goes to other people. My uncle and Hughes Engines for the component choices, and since my uncle passed away before we really got to building the engine I had to draw on a little more expertise there. I can take an engine apart and put it back together and get it to run, but I wanted more than that here, so I enlisted Moffitt and Bratton in Boise, who builds race engines, to do the machining and build.

It was kind of like the old sign; Engine work $50/hr ........ $75 if you hang around and ask stupid questions.

I paid the $75, but it's been fun ?

Was really glad to actually get to meet the Utah continent this year too. It's unfortunate that I miss most of the fireside chats with you all due to the kids, but still, they are worth it.

Definitely looking forward to SV 2022, and having another good Fairfield area route. Talk to GMoose today and we're hoping there is about 4 of us that show up with Tuckers that didn't make it to SV this year.

 

[1boringguy]

Perhaps anyone here knows more than I'm finding out.

When running the engine on the dyno Frank mentions that a 2800 rpm stall speed torque converter is recommended for the cam that is in this engine, and almost certainly the factory standard would have been 1800 rpm. Of course I'm not building a drag car, so I go to checking. Tucker was unsure of stall speed, but their new Allisons do come with the torque converter, not sure about back in 1989. Weller, the Allison dealer, said the at545 would have come with a torque converter, and Allison doesn't designate by stall speed but rather by percentage of slip. There is/was no lock up torque converter for the at545. They said there are only two torque converters available at this point in time, one for a gas engine, the 275 with 1.96 percent slip ratio, and the 290 with 1.72 ratio for diesels. There have been a couple others over time, pre 1992 the 275 was the 270 as mine is, and a 230 for diesels that was a 2.90 ratio. Higher percentage slip of course would equate to higher stall speed (smoother shifts?). Also seems the the at545 doesn't build up the pressure needed to lock up the internal clutches below about 2200 rpm iirc, which can cause damage.

It seems there is only one choice for the gas engine and that's what I have. It's recommended to replace or rebuild the torque converter when replacing or rebuilding the transmission due to build up or damage caused by shavings ect in the torque converter. My trans pan was very clean and magnetic plug were very clean so we just serviced the trans and putting it back in. I'm thinking the same with the torque converter.

The whole concern with the cam and stall speed of course, is not wanting the engine to die when put into gear at idle rpm because of the overlap of the cam. Even though we didn't try to idle below 850 rpm on the dyno because we couldn't unload the engine while hooked to the dyno, it idled very smoothly at 850 rpm. Guessing because of the stroker build and the efi.

Thoughts, knowledge, anyone? My gut feeling is I'm ok reusing what came out, but I just don't want to have to take it apart twice.

 

[Blackfoot Tucker]

Perhaps anyone here knows more than I'm finding out.

When running the engine on the dyno Frank mentions that a 2800 rpm stall speed torque converter is recommended for the cam that is in this engine, and almost certainly the factory standard would have been 1800 rpm. Of course I'm not building a drag car, so I go to checking. Tucker was unsure of stall speed, but their new Allisons do come with the torque converter, not sure about back in 1989. Weller, the Allison dealer, said the at545 would have come with a torque converter, and Allison doesn't designate by stall speed but rather by percentage of slip. There is/was no lock up torque converter for the at545. They said there are only two torque converters available at this point in time, one for a gas engine, the 275 with 1.96 percent slip ratio, and the 290 with 1.72 ratio for diesels. There have been a couple others over time, pre 1992 the 275 was the 270 as mine is, and a 230 for diesels that was a 2.90 ratio. Higher percentage slip of course would equate to higher stall speed (smoother shifts?). Also seems the the at545 doesn't build up the pressure needed to lock up the internal clutches below about 2200 rpm iirc, which can cause damage.

It seems there is only one choice for the gas engine and that's what I have. It's recommended to replace or rebuild the torque converter when replacing or rebuilding the transmission due to build up or damage caused by shavings ect in the torque converter. My trans pan was very clean and magnetic plug were very clean so we just serviced the trans and putting it back in. I'm thinking the same with the torque converter.

The whole concern with the cam and stall speed of course, is not wanting the engine to die when put into gear at idle rpm because of the overlap of the cam. Even though we didn't try to idle below 850 rpm on the dyno because we couldn't unload the engine while hooked to the dyno, it idled very smoothly at 850 rpm. Guessing because of the stroker build and the efi.

Thoughts, knowledge, anyone? My gut feeling is I'm ok reusing what came out, but I just don't want to have to take it apart twice.

1BG,

I know Tucker has worked with their local Allison dealer over the years to refine the transmission to Sno-Cat relationship. In a conversation with the Tucker factory, they suggested I call that dealer, Pacific Power Products, and more specifically speak to a fellow named John Edwards. I did call and found him to very knowledgeable, friendly and helpful.

When it comes to Tuckers and Allison transmissions, I think he's probably THE guy to speak with...

 

[1boringguy]

Thanks BFT,

I did in the past at your suggestion and did again the other day, try to find John Edward's at Pacific Power Products. They have several divisions/locations but the gal in the main office has told me twice now that they have no John Edward's registered as a company employee. I did get to Brad Robertson, field rep, who was helpful. He looked up my trans by assembly number, and also did some hunting about Allison torque converters.

Brad said my assembly number showed this trans left the factory with a 275 TC (would have been for a diesel). I thought maybe the trans was a rebuilt given how clean it was inside, which could account for a different serial number, but no, numbers match the Tucker door build sticker info. So have to guess Tucker changed the TC to match a gas engine at the original build time. I asked Brad what the actual differences were between the 270 and the 275, thinking the 275 was some sort of upgrade for the gas engine since these two are both 1.96 slip ratio. But again, no. He sent me this;

"Jack,

I had to go all the way back to 1985 to find a document that listed out the differences between the 270 & 275 torque converter.

• The 270 torque converter was originally built for both gasoline & diesel applications but in March 1985 the 270TC was transitioned to gasoline applications only.
• November 1984 the 275TC was introduced to replace the 270TC in all diesel applications.
• The 275TC utilizes brazed pump blades, thicker turbine blades and improved thrust washer material.
• An increased capacity thrust bearing assembly is utilized in both the 270TC & 275TC.

Other than the changes listed above the 270TC & 275TC are identical."

So, what I think I know here.

Allison rates the AT 545 at, max input 4400 rpm, min idle under load 500 rpm, max weight of vehicle 30,000 lbs, max hp 235, and max torque 445 ft/lbs.

I have the 270 TC which is the 1.96 slip ratio. The 275 was a 1.96 slip ratio but was made for a diesel. All other Allison ratio TC were made for diesels. The 275 might be built to better handle additional torque of a diesel, but perhaps not higher rpms, idk. The 1.96 ratio is my best option ratio wise. Weller truck shows availability of only the 290 (1.72 ratio) and the 270. And the 270 only as a rebuilt.

In checking with about half a dozen after market TC suppliers I haven't found any options offered by them, other than rebuilding the one I have.

My thoughts, again.

Weller, who serviced my trans, thinks I have little or nothing to be gained by using a rebuilt TC at this point. Ok. Brad pointed out that my hp is well over what the trans is rated at, and the torque is right at the top end. I'm going with it anyway for a couple reasons other than all the work it would take to accommodate a bigger trans. First, assuming a normal operating range of 2500 to 3500 rpm, the torque stays under the max and hp only slightly over at the upper side of those rpms. Secondly, under my snowcat operating conditions ranging from ice to powder, only a limited amount of torque can be created in the system before ground slippage occurs. Thirdly, I don't generally drive like I'm on a mission from God.

So after delaying putting the engine back in pending this education exercise, I think it's going back together with the 270TC that came out of it.

 

[Blackfoot Tucker]

1BG,

I wonder what happened to Mr. Edwards?

Sometimes in my phone conversations I'll keep notes, and I have "Pacific Power Products (800) 882-3860 John Edwards - Medford". My recollection of the phone call with Tucker (and that likely was with Jeff Godard) was that they worked with Pacific Power Products (and specifically John Edwards) in refining the Allison transmission setup in Tuckers. I recall talking with Mr. Edwards and I sought his advice on what he suggested to use as a transmission modulator. I found him knowledgeable and helpful...why I suggested him as a resource.

Out of curiosity I Googled "John Edwards Medford, OR" and got a few hits. If it's the same man, he is now the Regional Operations Director at Freightliner Northwest. But I think it's a fairly common name, so...

We're using the AT545 in both Thundercat and Snowzilla. Thundercat has an 8.1 Vortec engine and Snowzilla has a GM L94 6.2L engine. I purchased the 8.1 via eBay and I recall it came from a Chevrolet pickup truck. I purchased the AT545 from a truck salvage company in Colorado and it was originally installed in a Schwann's Food Company truck...behind an 8.1 Vortec engine.

GM offered that combination from the factory, and the 8.1 exceeds both the rated horsepower and torque numbers from Allison. I find it reassuring that GM thought is was a sound power train combination, despite Allison's limitations. The L94 makes a bit less torque, but more horsepower. Unfortunately it is more of a higher RPM engine and it makes its peak torque and horsepower at somewhat higher RPM.

I also subscribe to the theory that just about anything is okay...in moderation. As long as we don't thrash the heck out of them, I think we'll be okay. And it's not like these machines get a whole lot of use, anyway....

 

[1boringguy]

BFT,

Thanks for the input too. I didn't realize they had paired the AT 545 with the 8.1, that is interesting. Definitely a vote of confidence by GM I would think, since they were standing behind some kind of warranty there. Anyway I'm pretty sure my snowcat is going to have an easier life than a school bus, so I'm not worrying to much about using the 545 either.

 

[Blackfoot Tucker]

BFT,

Thanks for the input too. I didn't realize they had paired the AT 545 with the 8.1, that is interesting. Definitely a vote of confidence by GM I would think, since they were standing behind some kind of warranty there. Anyway I'm pretty sure my snowcat is going to have an easier life than a school bus, so I'm not worrying to much about using the 545 either.

1BG,

To expound a little bit on transmissions, some people think about the engines that the manufacturer has paired them with. For example Chevrolet put the Turbo 400 behind big-block engines for decades, or Chrysler put the 727 behind Hemis... so either should be more than sufficient in a snowcat....

But the typical automotive duty cycle is completely different than that of a snowcat. In an automotive application, the transmission is used to multiply the engines torques as it accelerates and shifts through the gears. Once up to speed, it really isn't subjected to all that much torque unless one climbs a long hill, and does so with a heavy load. Even in the Hemi example, in a drag race the transmission will shift from first to second and second to third...and that's it. Sure, it will be subjected to some serious shock loads and a lot of torque... for about 13 seconds at a time. But how much heat will the transmission build in 13 seconds? Now think about a school bus or a garbage truck. It weighs almost ten times that Barracuda or Charger/Challenger, and it is making frequent stops with accelerations between each; day after day after day. Almost always working...it's the difference between a thoroughbred and a pack mule.

In a rubber belted Tucker, the engine and transmission work hard almost continuously. For me, I think a transmission designed for medium duty trucks is more closely aligned with our needs than one designed for a station wagon or a muscle car. Back in the 1980s when Diesel engines were first introduced in pickup trucks, auto manufacturers paired those engines with one of their currently produced transmissions. And the result was a bunch of transmission warranty claims. Over the ensuing years, the Diesels have gained more power and the transmissions have gone through several evolutionary cycles of upgrades so they will hold up the rigors they're subjected to.

A turbo 400 transmission weighs about 135 pounds and a Chrysler 727 weighs about 160. Put them together and your right at what an AT545 weighs; about 289 pounds. I'm sure the difference in weight is not just the case, but rather beefier internal parts and clutches, etc.

But all that said, I'm not an automotive engineer. The above are the ramblings of a snowcat enthusiast, and Grade A knucklehead...

 

[1boringguy]

Lol, kind of reminds me of welders.

One can get an gas engine driven 250 amp welder for about $2500-3000 (old prices), that is light weight easy to throw in and out of a pick up and is great for little projects. It has about 20% duty cycle and needs replaced after about 2500 hours.

Or one can get a diesel engine driven welder with twice the weight and size, that has 80% duty cycle, electronically controlled weld characteristics, and lasts 10,000+ hours, for $10,000 (again very old price). A gotta have, for pipes that can take 6+ hours to make a weld.

As with anything, it's good to understand what the differences are and use case. And that there is rarely any free lunch.

 

[Mill666er]

My 1981 542A HD with the 4-53T was originally equipped with the AT540 which I read wasn’t a very robust design. The transmission was rebuilt/swapped by Stewart & Stevenson to the AT545. The 4-53T is 175HP @2500 and 440 lb ft at 1800 which takes the AT545 to its limit. It seems to run best or most bearable around 1900rpm and don’t think I have really taken it over 2300. I don’t have any info on the torque converter and didn’t pull it off when I had it out. It is a very hard shifting and knocks you back in the seat if that is possible below 12mph.

 

[1boringguy]

Mill666er,

Would be interesting to know if it has a number on it, or if it's something other than from Allison. Surely made for the lower rpm diesel applications though.

 

[olympicorange]

all very good info & history ,... and yes these 545's will snap your head when put in a snocat,... most likely due to the weight difference from a school bus , medium duty truck, etc. and not letting up with the right foot,... but who else makes a tranny that you can mate up to just about anything, and is nearly indestructible. the down side is reverse is slow . i was sold on these 30 years ago when i had a customer with one in a timberjack skidder. we repaired just about everything on it , except the 545 ,.... there's tons of them around & they're cheap to buy,.... my 4 BT's can't kill them. the most important factor is a proper cooling system for the trans. keeping the heat down is the key to longevity . ..........

 

[Mill666er]

Not sure when it was remanufactured, it was sold to Aspen Ski In 1981 but then was bought by Snoqualmie Ski area before I got it.