Getrag Preload thread....here we go again

[ahale2772]

My rag will be coming out shortly because its making some god awefull noises. (mostly 4th gear low rpm growl, cant even hear myself think kinda growl ) seems like it has just become progressivly more loose over the last 2 months.

shifting has not changed (would it?) and synchro engagement feels the same.

anyways... when I rebuilt it (about 8k miles ago) I set the preload tight. I forget what the manual says for preload, but I was on the high side of the tolerance (im sure I was literally on the high end of the tolerance)

anyways.... always put good oil in it, but its about dead

7th post down here has a really good post about preload

http://www.dieseltruckresource.com/dev/ ... 99773.html

what should I set it to this time? .006?

edit, set the preload to .008... according to the rebuild thread I had up, cant see how 2 thousanths would be the difference between life or death.....?

[Mark Nixon]

Looser is BETTER, but it MUST have pre-load when it is warm.
It would be nice to know the expansion rate of the total assembly.
I've ran both, tight on the pre-load, or loose on the pre-load, and they just seem to feel better, when shifting, the looser they are pre-loaded.

Mark.

[PToombs]

I've set mine on .007 both times I changed the bearings, which is the middle of the spec, and had them loosen up a lot. Well, the 1st time the bearings looked like metal went thru them, the 2nd they were loose and I reshimmed to either .003 or 4. After I hauled that big camper I think it got loose again, it rattles in neutral. I drove it to SOP and back and didn't have any problems, but I'm going to check it and reshim to 0 if it's loose again.
I think it just needs to be checked and adjusted a few times after it gets rebuilt to get it right.

[dpuckett]

I set one to .005 due to a lack of the proper shim to get it within spec. I think it was the best performing transmission of the half dozen or so I've done.

[ahale2772]

I think it just needs to be checked and adjusted a few times after it gets rebuilt to get it right.

if thats true.... then that is a PITA im not exactly thrilled about pulling the trans apart again...and again........and again

Pete can you re-do the preload on a 2wd truck while its on the truck? i imagine it would be hard to get an accurate measurement if the shafts arnt verticle.

I wonder if I should just set it at like .005, like Dpuckett said? either way hopefully ill actually get a shim pack from Zbag this time, they negleted to send me any last time

me thinks someone needs to invent some kindo of oil pump system with some bearing oil squirters for this trans..... that would be helpfull

[Mark Nixon]

In the case of Pete's "Wandering Pre-load", I'm wondering if the bearings aren't fully pressed onto the shaft and creeping a little at a time.
Another thought, I've always wondered at the machining of the bearings.
New, the bearings and races always seem to have this fine machining mark in them and after a few 10s of thousands of miles they are usually gone.
Even at .0001" of wear per piece, that has to add clearance to the assembly.

Sometimes "hard" pre-loading an assembly is worse than not pre-loading it enough.

Mark.

[ahale2772]

Yeah, good point mark.

I hate thinking that my input shaft/pilot bearing is helping keep my transmission togetgher though. the input bearing, poket bearing and main bearing are all taperd bearings, therefore one wears, the all sag and then they allwear. the nose of the input it held by the pilot bushing/bearing and therefore hopefully keeps itself inline...

thats just the way my brain thinks anyways

interesting that they dont make translissions like the NP205 input output setup, with straight roller ballbearings , and needle bearings that directly work against side load...

but what do I know, im sure transmissions have been designed like the getrag far before my time

[PToombs]

Maybe it's just me, but i did the setup to the FSM specs. Maybe there was something wrong with my setup, I can't answer that. I'm good at pulling the trans now, I can tell you that!
And no, you can't do the preload in the truck, the bearings are all tapered and it just doesn't come out right. It's hard to check in the truck too, the CS is easy, but the main is barely accessable it moves too much. Rotates I mean.
As for the shim packs, you need to order them, they don't come with the bearing kit. MM and I have discussed the oil pump/cooler/ squirters at length. Unfortunately, neither of us has time to build any thing, yet.

Mark, bearings are set on the shafts just fine, and the races are bottomed out too.

[ellis93]

Mr Pete I wonder if your case is warped/out of square and causing your trans' repeat offense. I've had to patch mine up 5 or 6 years ago and I didn't know anything about the preload on these trans so I set it up where there was no slack and no tightness. This was with old bearings and one new 3/4 syncro assembly. Now fast forward 5 years now the 1/2 assembly seems to have problems

[Horus]

Ha, log on achieved!

When I had my Getrag rebuilt I went through a buddy's friend. He works for a good transmission shop and does rebuilds on the side. This was a cash and handshake deal. When I picked up the trans I asked him what he set the preload to, he said .005! I knew it was supposed to be 7 to 9 so we talked.

In the end he told me if I had any trouble at all to bring the whole truck down and he'd fix everything. He said he always thought .008 was just too tight and had done several Getrags with .005 never having one come back. Two are in his friend's rigs running smooth to this day. He was adamant that the bearings must be fully pressed on, something he could do at work.

Fast forward two years and the 'rag is still kicking ass. I gave it 400 miles of light driving around town and later on the highway to break it in. From there on 95% of my trucks use is towing a 4400 pound rig on a 10K trailer to and from the trails almost every weekend. Thousands of miles now of almost pure towing and all is well.

I run one fast cooler and VR-50 oil, .005 preload. No problems. It even shifts better with the 12 inch shifter extension. I am sold on looser.

[ahale2772]

yup thats how ill be doing it,

as a side note, is the bearing race in the Input replaceable? i remember the pocket bearing came with a race last time but i never used it cause I went with a new input. Im driving this bugger till next weekend and then I'll rip it apart, hopefully it wont tear anything apart till then

[Mark Nixon]

That race is NOT replaceable
They include it because the bearing and race are usually sold in sets.

As I and some shops have said, "looser is better, but there MUST be pre-load".
I believe as low as .002" in pre-load would still be adequate.

Less preload=less heat=less wear.

Mark.

[PToombs]

If you use old bearings there should be no preload, no play, 0 clearance.

Mr. Ellis, maybe, but it's been ok this last time except for the slight noise in neutral. It'll be a long winter, lotsa time to check it.

[ellis93]

MM and I have discussed the oil pump/cooler/ squirters at length. Unfortunately, neither of us has time to build any thing, yet.

This sounds,to me anyway,like a cool idea but don't the gears already sling oil everywhere. Well every where except the pocket bearing and then even the squirters couldn't get to it. With the one qt over fill aren't we already getting close to all the bearings?
I bought one of alex's covers awhile back and had hoped to have a coolings system made where I'd plumb into that clear cover with a suction and discharge. I was going to take a solid plug and cut a slit in the top and drill through the center to make a squirter of sorts. I thought it would resemble a pressure washer nozzle. I would take said nozzle and screw it to the discharge side and aim it at the input and main shaft, effectively cooling the syncros. I had also thought that at the same time to incorporate a cooler from an auto trans to lower and control trans temps. The only thing that has stopped me is finding a suitable pump to use in the oil and produce the pressure I want. Anybody know of such a pump?

[Richie O]

MM and I have discussed the oil pump/cooler/ squirters at length. Unfortunately, neither of us has time to build any thing, yet.

This sounds,to me anyway,like a cool idea but don't the gears already sling oil everywhere. Well every where except the pocket bearing and then even the squirters couldn't get to it. With the one qt over fill aren't we already getting close to all the bearings?
I bought one of alex's covers awhile back and had hoped to have a coolings system made where I'd plumb into that clear cover with a suction and discharge. I was going to take a solid plug and cut a slit in the top and drill through the center to make a squirter of sorts. I thought it would resemble a pressure washer nozzle. I would take said nozzle and screw it to the discharge side and aim it at the input and main shaft, effectively cooling the syncros. I had also thought that at the same time to incorporate a cooler from an auto trans to lower and control trans temps. The only thing that has stopped me is finding a suitable pump to use in the oil and produce the pressure I want. Anybody know of such a pump?

My uncle has used Holley black, or blue fuel pumps before to use as a cooling pump for rear axles in high performance stuff. Hot oil is thin enough for that to work well.