Transfer case torque mount

[Orange Crate]

haskins10;
You had other issues going on before that failure, it wasn't because you don't have the torque mount. I would guess that your trans mount was toast and let loose, allowig the rest to bounce around.

jaros44sr;
Do what Dirty Larry says.....he is right.

[67chevyk20]

I know this thread is a few years old, but wanted to post what I found in order to help future visitors. The picture in #7 is correct. If you look at the lips when you have them apart you can tell that they have worn a pattern to each other. I just tore 2 of them apart and the lips were facing each other on both. Hope this helps!

[mattfrediani]

can someone tell me how much torque i should put on these new torque mount poly bushings? gorilla tight or snug?

[B. W.]

Just snug them, the poly mounts are harder than the rubber & you want some give in it. If it is super tight you are more likely to break your tcase adapter. also, as stated earlier (many years ago!), check your motor mounts, if the driver's side breaks (and they are notorious for breaking) it will break your tcase adapter.

[mattfrediani]

I have upgraded the tranny, and case with poly mounts, I want to do the motor now.
Is it hard to just lift the motor with a block of wood at the pan and remove the old rubber and get new poly mounts in?

[B. W.]

I'd use a floor jack on the oil pan with a couple of blocks of wood to protect the pan. Loosen all other mounts before lifting engine. If you have an engine hoist you can raise the front of the engine, you still want to loosen all your mounts first.

[mike16]

so where can one get the case rubber bushings?

[jaros44sr]

Originally Posted by mike16

so where can one get the case rubber bushings?

Rubber, I don't know, prothane has poly

[mike16]

I just finished pulling my adapter mounts and torque plate rubber bushings apart to clean inspect and re-install them. Attached are a few images I hope they help.
The torque mount is critical, It provides a whole different purpose than motor mounts or the adapter/tanny mounts.

Motor mounts and the adapter mounts fix the engine, transmission and transfer case in place, For the most part they support the weight of the drivetrain and its weight generaly fix them or hold them in place. The only fasteners that hold the engine in place do not pull it together from top to bottom but are installed to simply hold the two parts of the mount system, the frame mounts and the engine mounts together. weight keeps them pretty much in place. the through bolts hold everything together and prevent the engine from rocking too much either left or right. They dont hold anything in tension.

Ditto for the transfer case adapter mounts. its the weight of the drivetrain that holds them in place. the through bolts simply keep everything snugged up and in place. That being said, those bolts dont need to be very tight. I looked at mine and noted how much of the bolt protrudeds above the adapter before dis assembly( digial camera an absolute must). and turned the bolt untill about the same amount extended beyound the cast iron adapter upon re-assembly. No torque for two reasons...1. too much torue is not needed and is detrimental, too much torque preloads the mount and does not allow it to do its multifunctionl job, 2. those special lock washers, available cheap from several vendors when used...properly keep the bolts tight and prevent them from backing out.

Any "preload" should come from the weight of the drivetrain and NOT,NOT from over tightening those bolts. when the full weight of the drive train rests fully on the mounts witch will settle a bit and bulge out a bit. thats typicle and acceptable. But once you do that, do not continue to tighten up those bolts untill the rubber mounts distort further, maybe a very slight amount of distortion but no breaker bars with 4 foot pipe sections on the end. It does not work like that and too much Preload from tightening will surely brake the adapter. the weight of the drivetrain holds everything in place, the fastener keeps everything fixed in place and that strange little lock washer prevents it all from comming loose. Not massive amounts of torque from a breaker bar.

Another thing that worked for every in the past and workes even better now is a caulking tube of RTV window and bathroom sealant. Its 4.99$ at Ace and I use it to Litteraly Glue the upper and lower tranny adapter mounts together. The current mounts are one size fits all and there are alot of sloppy fit, airgaps around the mount where it interfaces with the cross member. so I fill in the gaps, including serious ones around the steal tube through bushings/sleave that goes around the through bolt. I slop it all up with the seallant. I tighten up the through bolt and let it sit for a full 24 hours.

Note: I have not attached or fixed the crossmember to the frame. the trany is supported by a floor jack and wood blocks.only the glued mounts are slightly fastened to the crossmember for the 24 hours.
24 hours later I loosen the tranny adapter through bolts so that the cross member is flopping around loose to the frame and the tranny adapter.
then I tighten up the cross member to frame fasteners
then I tighten up the tranny adapter mounts to the adapter. then I lower the jack so the full weight of the drive train is resting on the mounts/crossmember

then I tighten up the through bolts untill just a slight additional amount of distortion is percieved at the rubber mounts.

then I bend the lock washers such that they prevent the through bolts from lossening

Points to remember:
If your motor mounts or tranny mounts are bad ,failed, soft or oozing. they need to be replaced. If not, other things will break on a regular bassis untill you get it.

tightening the tranny adapter mounts too much, defeats thier purpose and will increase the chance the tranny adapter will fail. Tighten Just enough to see a little more distortion beyond what the full weight will do. Just a little. Use the lock washers to prevent loosening of the fastener/hardware. torque does NOT do it, lock washers do.

It must be remembered that these trucks were not envisioned to be rock crawlers or mud boggers. They were intended to provide conservative operational mobility over rough terrain.The frames flexed, that is normal. four wheel drive flexed even more, and with a load in the bed they flexed even more. the engine, bellhousing transmission, adapter and transfer case were not flexible and if they were fixed firmly to the frame they would crack everywhere and bust out chunks of cast iron. And with this knowlege and several years warrenty experience. It continued to be a problem and some might agree it got worse as trucks became more powerfull, heavyier and used with more wreckreational enthusiasm.

So its important that the mounts be good and not oozing, dryrotted or broken.

The torque Mount
That Torque mount serves a totally different purpose and if its not installed there is a different but equally likehood that the tranny adapter will fail.

Think about it, torque is twisting motion, the torue mount allows a little bit but limits the twisting force of torque beyond the engineered limits.

You have a six, an eight or a bigblock providing twisting force, then there is a flywheel, then low gear, a low range in a two speed transfer case, 456 gears, and what ever tire size is factory recommended. when all tht twisting force meets the ground something must give a little bit because the tire grip is fighting the drivetrain forces and your engine wants to twist, your tranny and t case want to twist. when the t case wants to twist engineers said ok, a little is nessessarry and even good but it cannot be allowed to twist the rest of the drivetrain or other components will fail. And it cannot, nay.. must not be to ridgid because it will weigh too much and will never be totally rigid. little flexing is OK, even good for noise comfort levels.

that tcase torque mount allows the t case to float under normal load, but as torque winds up the drivetrain the t case will try to rotate, loading up the mounts and it could cause damage if allowed to twist too far. so under normal load it floats and the bushing rubber mounts and ,again, just kinda held in place but as it winds up the mounts come into play and resist further twisting force so that the torque does not wtist or damage other parts.

It looks kinda flimsy and loose but thats at normal loading. You will note that it extends out from the side of the t case and only a little bit of moment arm is all that is needed to stop the t case from twisting further. Thats all it does is prevent exessive twisting of the back of the engine/tcase.it keeps the compression load of the t case adapter from becomming a twisting load that will snap off either an aluminum or a castiron adapter,

The engineers put it in there for a reason, It took labor to design, test and assemble and install it and it cost to cover it under warrenty. plus the actual cost of the parts them selves and not to mention the logistics of keeping spares in the invantory.

Think about it. thats a very expensive part were it actually to be so unnessassarry. and to be the cause of so much additional part failure.

I worked in the army as a wheel mechanic and later as a contractor.

Those adapters faile often in the cucv's. in every case the cause wqas one of two things, either the adapter mounts were too tight and or the t case mounts were tightened up to spec BEFORE the transfere case was installed.

I saw one soldier brake one adapter between 8 and noon, the second one by 2 pm and befor 4 he had broken a third one.

On civilian trucks when you put heavyier springs shocks and big azz tires on these old girls a third possibility for failure occurs. all the torque is consentrated between the flywheel and the drive shafts, that twisting motion and ressistance consentrates the tourque between fewer and increasingly "underengineered" Parts. Somethings gotta give.

it may be u joints. drive shafts but eventually the mounts will fail. and not the cheap replaceable rubber mounts but the expensive hard to find, expensive to ship, gets lost in the mail, tranny adapter

[mike16]

attached are some images of the torque mount and adapter mount.

I glued the adapter rubber mounts to the crossmember and filled in any air gaps or spaced. the current after market tranny mounts are a sloppy loose fit all around but work when the weight is fully on them. but there are two steel sleaves or tubular bushings that slid up into those mounts. There is alot of airspace and gaps around what should be normally very well supported. I filled it all in with the RTV sealant caulking.

I got the sealant at Ace. for 4.99 vs about 1 fifth that amount from NAPA for 8 bucks.

glued it all together, snugged up the fasteners and let it vucanise for 24 hours.

when its all dry I trim off the exess with a razor.

the t case adapter rubber mounts were brand new . the t case torque rubber bushings were origonal and in good shape. I cleaned them off with GOJO type hand cleaner. Its very forgiving and does not rot them like petroleum based cleaners do. protects and softens and they shine like new.

I hope the pictures help. especially with missing parts and correct reassembly.

[mike16]

I use GOJO handcleaner to clean off dirt and grease. It protects the origonal painted finish, and harmlessly cleans up rare, impossible to find rubber bushings. I also use simple green and it too is very forgiving.

the caulking gun is filled with an RTV type caulking substance in a dark grey pigment, white and clear are also available. I accidentally bought some black roofing asphalt/cement . wrong stuff. read the label and avoid multi trips to "the place". after it dries for 24-48 hours trim exess ooze with a razor.

One more thing I keep harping on. tightening hardware will not ensure that it stays tightened. lock washers do that. It works witht the t case adapter rubber mounts, and the torque mount wher the brackets fasten to the fram c section and the torque mount through bolts.

dont over tighten. If your motor mounts are bad in any way or over 2 years old... replace them and the t case adapter mounts and if you can, salvage the rubber torque mount rubber bushings, or replace them with the prothane bushings, If ya gotta replace one component, replace them all. do them all at once. its the best 100 bucks you can spend

I hope I have helped

[DirtyLarry]

Originally Posted by mike16

The engineers put it in there for a reason, It took labor to design, test and assemble and install it and it cost to cover it under warrenty. plus the actual cost of the parts them selves and not to mention the logistics of keeping spares in the invantory.

The engineers also removed the transfercase to the frame brake around 1974 or 75 for a reason and moved to a support rod that tied the tcase to the engine bellhousing bolt so the entire assembly would rotate at the same frequency….

Here is a link to a thread from years ago with information straight from a GM engineer

[mike16]

Yes but also stiffened up the drive train because in conjunction with those reinforcing rods the flange on the 350 tranny's were thicker than for standard 350's. those 4x4 transmissions were very desirable in drag racing.

which makes proper motor and tranny mounting more critical. the frame must and invairiably will flex but you dont want that flexing to be transmitted to the engine and tranny. they must be able to move around separatly from the frame. not alot but enough. the rubber lets them do that among all three axis'.

Bottom line is that the drivetrain is not a support or structual member. aint formula 1.

[Zoomad75]

The engineers put it in there for a reason, It took labor to design, test and assemble and install it and it cost to cover it under warrenty. plus the actual cost of the parts them selves and not to mention the logistics of keeping spares in the invantory.

Think about it. thats a very expensive part were it actually to be so unnessassarry. and to be the cause of so much additional part failure.

Engineers get it wrong too. Ever hear of recalls? That's when the engineers get it wrong. Getting back to the mount, like Larry said, the 205's lost the mount early in the squarebody production run. They kept drilling the holes, but no mounts on the frame. Later the 205's lost the mount. WHY? For the exact reasons Larry has noted earlier in this OLD thread. You want to crack the adaptor bolt that sucker up like you show.

Those adapters faile often in the cucv's. in every case the cause wqas one of two things, either the adapter mounts were too tight and or the t case mounts were tightened up to spec BEFORE the transfere case was installed.

I saw one soldier brake one adapter between 8 and noon, the second one by 2 pm and befor 4 he had broken a third one.

Lets see, I'm not an expert on CUCV's, but by that time in the production run GM stopped using the torque mount for close to 10 years. I can see a certain point to getting the order of torquing things up screwed up, but those didn't have the mount you've expounded on at length here.

To go back to the point that GM changed the idea on the torque mount use, please explain why the 208 and 241 t-cases never got the bosses cast into the aluminum cases on them? The 208's were used in the M1009's too.

You've got a point that GM did put a lot of thought into the engineering behind the torque mount in the first place. But warranty claims are the best feedback a manufacturer can get. As GM started seeing the cracked adaptors coming in you can bet a service engineer is going to get assigned to find out why. If what they find is going to lessen the warranty expense they will make a change. GM does this now just as they did it back then. It just took more effort back then due to the lack of computerized data and reporting like they have had for the last 25 years.

But hey, I only worked at GM for a good chunk of my career, International for another and a GM dealer for the last 9 years so I might be wrong too.

[Zoomad75]

Sitting here eating my lunch I looked up the parts images on the 85 k series trucks in the gm parts catalog. Hmm I was wrong on one level. The 208 case does have mount holes in the side of the case similar to the early 205's. However they used them to mount the strut rod to the trans bellhousing.

Seems as if GM wanted the t-case, trans and engine to rotate under torque in the same fashion. The strut still helps support the weight of the t-case but not tying it to the frame allows it to rotate with the trans rather than tie it down.

The whole point is if you tie the passenger side of the t-case down but the engine can still lift up off of the passenger side mount under forward torque the result will either crack the bellhousing of the trans or the t-case adapter.

GM did make a change in design and wisely moved away from the side t-case mount. For you 67-72 4wd guys it's up to you to run it or not. If you want a 100 point dead nuts original restoration you'll want it there, but twisting it up off road will be the last thing you do so it probably won't break anything. If you do intend to play in the dirt, be aware gm didn't use interlocking engine mounts until 73 so the older stuff will allow a lot of movement if the passenger side mount breaks. Add that with the torque mount and a heavy right foot you will see the adapter break on a manual trans truck or the bellhousing on an auto.

Just depends on how you use it.

[BILT4ME]

We have a 1970 GMC K2500, 350/4SP/205

It has seen a LOT of towing in its life. The rear pinion was replaced once, the spiders blown out, and the center pin welded into the carrier.

The T-Case mount has the lower part cracked and broken off where it bolts to the 205.

The engine mounts in it were not broken, but I'm sure they have been replaced multiple times.

We are replacing all transmission and engine mounts, but we are also adding the Torque Limiting Cables used on the 64-69 Impala's.

I think after reading all the pros and cons of all this and seeing what is actually already broken on our truck, I think this will allow us to use the truck and limit the amount of twist it will see if being used hard.

I previously built a 69 K1500 using a 1960 frame with the divorced T221 (3 driveshafts) and it HAD to be mounted separately. I used the torque limiting cables on it, and I was able to pull out loaded semi's, dump trucks, and tree stumps without rolling over the engine or breaking the engine mounts.

I would have preferred to also upgrade the engine mounts to those used in the 75-87 trucks, but I didn't want to modify the frame cross members.

I do recall on my brother's factory stock 1968 K20 HD with a 292 6 cyl, 4Sp,and married T221, that he had to replace the cast adapter between the trans and TCase once due to having broke in half. Yes, that TCase was secured by the rubber mounts on the side as well.

So, I have personally seen (2) manual transmission trucks with the married TCase that have broken either the adapter or the bracket.

I will remove the bracket from our rebuild on the 1970 GMC. We'll see what happens.

[mattfrediani]

Damn Im Torn, What to do?
My K20 with a new TCI TH350 And a custom built NP205 from Moonshine Mafia (Ryan) going in the truck next week. she's just a street wheeler and might see some camping but more of a low level car show queen. I won't be off road with this truck so Im leaning towards putting the frame torque mount back in with new poly bushings / new poly trans mount. Im also upgrading the adapter to a beefier one. What would you guys do? My motor is just a mild 350. If I buy the torque rod from eBay that connects the NP205 to the bell housing will it fit with out modification? How easy it this rod to install?

[Redcap]

Originally Posted by mattfrediani

Damn Im Torn, What to do?
My K20 with a new TCI TH350 And a custom built NP205 from Moonshine Mafia (Ryan) going in the truck next week. she's just a street wheeler and might see some camping but more of a low level car show queen. I won't be off road with this truck so Im leaning towards putting the frame torque mount back in with new poly bushings / new poly trans mount. Im also upgrading the adapter to a beefier one. What would you guys do? My motor is just a mild 350. If I buy the torque rod from eBay that connects the NP205 to the bell housing will it fit with out modification? How easy it this rod to install?

The rod is easy to install. I'd throw that frame mount into the scrap bin where it belongs.

['63GENIII]

Originally Posted by mattfrediani

Damn Im Torn, What to do?
My K20 with a new TCI TH350 And a custom built NP205 from Moonshine Mafia (Ryan) going in the truck next week. she's just a street wheeler and might see some camping but more of a low level car show queen. I won't be off road with this truck so Im leaning towards putting the frame torque mount back in with new poly bushings / new poly trans mount. Im also upgrading the adapter to a beefier one. What would you guys do? My motor is just a mild 350. If I buy the torque rod from eBay that connects the NP205 to the bell housing will it fit with out modification? How easy it this rod to install?

That would suck to break the BH of a new expensive transmission BC of an unnecessary mount. Just my .02. After reading all the above posts, if I didn't have a divorced case, my decision would be clear.

[El Dorado Jim]

dont use the side mount that attaches to the frame, it can break your t-case.....

[mattfrediani]

So the rod is easy to install? My only fear is if i order the rod it will be from a TH400 Np205 set up rather then a TH350- Will the rod fit both transmissions? I thought a TH400 was a longer Tranny. Thanks for your help guys!

[mike16]

Originally Posted by Zoomad75

Engineers get it wrong too. Ever hear of recalls? That's when the engineers get it wrong. Getting back to the mount, like Larry said, the 205's lost the mount early in the squarebody production run. They kept drilling the holes, but no mounts on the frame. Later the 205's lost the mount. WHY? For the exact reasons Larry has noted earlier in this OLD thread. You want to crack the adaptor bolt that sucker up like you show.



Lets see, I'm not an expert on CUCV's, but by that time in the production run GM stopped using the torque mount for close to 10 years. I can see a certain point to getting the order of torquing things up screwed up, but those didn't have the mount you've expounded on at length here.

To go back to the point that GM changed the idea on the torque mount use, please explain why the 208 and 241 t-cases never got the bosses cast into the aluminum cases on them? The 208's were used in the M1009's too.

You've got a point that GM did put a lot of thought into the engineering behind the torque mount in the first place. But warranty claims are the best feedback a manufacturer can get. As GM started seeing the cracked adaptors coming in you can bet a service engineer is going to get assigned to find out why. If what they find is going to lessen the warranty expense they will make a change. GM does this now just as they did it back then. It just took more effort back then due to the lack of computerized data and reporting like they have had for the last 25 years.

But hey, I only worked at GM for a good chunk of my career, International for another and a GM dealer for the last 9 years so I might be wrong too.

No, your not wrong, but I may be unclear in my statement, the torque mount is different than the adapter(the part between the t case and the tranny)the torque mount was eliminated but they still had problems with broken adapters even in the cucv's. I think its a service related problem rather than a design issue.

I would also suggest that the need was still there but as these vehicles evolved the way the problem was solved was different, same problem....different solution. money being a factor in that design/descision

My 68 k20 has only 13k miles on it and that torque mount will see alot of service....climbing up that ramp into the trailer.

I know about the recalls. they had them for the motor mounts in these year trucks, A failed motormount on these k trucks would make the problem worse and failure of parts more likley, the adapter specifically. Yes engineers will get it wrong sometimes .

the fact that the boss's are there makes me thing they might have had other possible/future applications in mind.

I never knew that there was a problem under warrenty.

It would be very interesting to look at the statistics on warrenty work back then.

someone else above mentioned adapters failing after new motormounts were installed. I have replaced motor mounts on these trucks and it is nessessarry to raise the engine to remove and install new mounts. if you just jack up the motor to gain the needed clearance to install the new motor mounts it must be raised high enough to do that but its too high(in my opinion) and puts a stain on the adapter, it too will put an unnatural load on the adapter mounts and the torque mounts. the adapters may fail.

[Redcap]

Originally Posted by mattfrediani

So the rod is easy to install? My only fear is if i order the rod it will be from a TH400 Np205 set up rather then a TH350- Will the rod fit both transmissions? I thought a TH400 was a longer Tranny. Thanks for your help guys!

Very easy to install. TH400 is about an inch and a half longer.