DOHC: 1, Isuzu: 0 -- Getrag swap!

[Series8217]

Didn't any of the formally educated morons who design this stuff ever hear about Occam's Razor? Complication for complication's sake is masturbatorial and counterproductive.

Maybe they liked being very cruel to the service department. :sad2:

[The Dark Side of Will]

I am absolutely positive that a maintenance review of the A-body was NEVER done... :scratch:

[The Dark Side of Will]

The stand-offs are:

4.5088
4.5109
4.5088
4.5082
4.5079
4.5084
4.5080
AVG: 4.5087

26935-2 (Input shaft)
4.3750 + 0.3494 - 0.2466 = 4.4778
Difference: 0.0309 (!! WTF?!?)

26935-4 (Output shaft)
4.3775 + 0.3757 - 0.2530 = 4.5002
Difference: 0.0085

26935-3 (Differential)
4.3814 + 0.3778 - 0.2598 = 4.4994
Difference: 0.0093

Positive Difference -> Tool gap wider than actual gap.

[Series8217]

The tools for different parts of the transmission have different gaps? Wow, GM sucks at life.

Is it necessary to reshim the input and output shafts when switching cases? I don't recall there being any taper bearings on those, but I didn't take apart the endplate..

[The Dark Side of Will]

Not on the 282. The Muncie uses tapered rollers on all three shafts. I'm going to re-measure the one that's screwy... maybe I suck at life... or at least micrometer reading.

[Series8217]

Not on the 282. The Muncie uses tapered rollers on all three shafts. I'm going to re-measure the one that's screwy... maybe I suck at life... or at least micrometer reading.

:sad2: quit hogging the tools

[The Dark Side of Will]

That's just the input shaft gauge. You don't need that one. I sent the toolset with only the gauge you need to save on shipping.

[Series8217]

That's just the input shaft gauge. You don't need that one. I sent the toolset with only the gauge you need to save on shipping.

I was just kidding Will! Thanks.

I sent the payment again bank transfer this time, sorry about that.

[Series8217]

Will, I got the tool today. Thanks!

The gap I measured is .027. Smaller than I expected. If I am really to subtract .006 from the gap to get my shim thickness (-.010" according to your most recent measurement, +.004" for preload) I end up with a shim that's like .007" smaller than the smallest shim used in the two transmissions I built this one out of. I tried to measure the tool with my calipers and ended up with similar measurements to yours so I'm not doubted their correctness. I'm just not sure its right for whatever reason. Seems odd that Timken might make the races a few thou thicker if they've usually been pretty close in the past.
I did notice on the tool box the directions say that the measured gap is what shim to use. If the Muncie 4-speed uses the same bearings, shouldn't they be preloaded to the same spec? There's no reason the tool should produce a different gap in the 4-speed..

[Series8217]

I just got to thinking.. do we know for sure that the Getrag tool gap is the actual clearance?

[The Dark Side of Will]

We don't know for sure, but we can infer so from the manual procedures.

With the three gauges compressed, the gap between the outer sleeve and base pad is larger than the correct preload shim at each location. Carefully compare the gap to the available shims. Determine the largest shim that can be placed in the gap and drawn through without binding. Then use the next shim size smaller on the output shaft and differential for reassembly. On the input shaft, use a shim two sizes smaller. If end play occurs, use the next larger shim sizes (Figure 7B-34A).

The GM shim interval is .004", so if the tool gap were the same as the actual gap, this procedure would set the Muncie up with loads of end play on each shaft, but since the tool gap is NOT the actual gap, then you can work through the numbers and see that the differential is actually set up with .003-.004 preload.

Measure the largest shim possible in area 'U', use shim TWO SIZES LARGER (Chart, Figure 23).

The interval for these shims is .002, so using a shim 2 sizes larger with measured gap and actual gap the same will set the diff up with about .004 preload, or about the same as what the Muncie procedure ends up with.

See my thread titled "Muncie Insights" for a listing of the Chrysler shims that can be used in the 282 and Muncie.

[Series8217]

We don't know for sure, but we can infer so from the manual procedures.

With the three gauges compressed, the gap between the outer sleeve and base pad is larger than the correct preload shim at each location. Carefully compare the gap to the available shims. Determine the largest shim that can be placed in the gap and drawn through without binding. Then use the next shim size smaller on the output shaft and differential for reassembly. On the input shaft, use a shim two sizes smaller. If end play occurs, use the next larger shim sizes (Figure 7B-34A).

The GM shim interval is .004", so if the tool gap were the same as the actual gap, this procedure would set the Muncie up with loads of end play on each shaft, but since the tool gap is NOT the actual gap, then you can work through the numbers and see that the differential is actually set up with .003-.004 preload.

Ah, ok. I don't have the 4-speed manual so I was just looking at the directions on the tool case itself; it says that the gap is the actual shim size to use.


Looks like the Chrysler P/N for the shim I need is 5222346... and it lists for $27 at Chrysler Parts Direct. HOly shit! The next size up is only $5. I better check if GM has some of these in stock still..

[Series8217]

This is interesting. I have a copy of the 282 repair manual and it says to use tool J26935. That's this tool Will sent me. Sooo the Getrag uses the same tool as the Muncie 4-speed. Now the preload specs make no sense, as the Getrag directions say

-Determine largest shim without binding
-Use shim two sizes larger.

Which would give far too much preload (about .014")

And the 85 sunbird manual as you posted says

-Determine the largest shim that can be placed in the gap and drawn through without binding.
-Use the next shim says smaller on the [...] differential.

Which would give about .008" of preload.


BTW Will, The GM shim interval is actually .5mm (close to .002") NOT .004" as you previously mentioned. I have the chart in my rebuild instructions. Also the measurement in thousandths specified in the charts is ROUNDED. The true measurement of the shim is the metric dimension listed in the chart below. You will be off by a thou from the rounding error if you go up enough shim sizes in thou and not millimeters, hence the chart chumping from .0030 to .0031 from the 0.80mm to 0.85mm shim (one shim size larger).

Code: Select all

GM DIFF SHIM P/N ...  THICKNESS mm (in)
140821xx
	32		0.30 (0.012)
	33		0.35 (0.014)
	34		0.40 (0.016)
	35		0.45 (0.018)
	36		0.50 (0.020)
	37		0.55 (0.022)
	38		0.60 (0.024)
	39		0.65 (0.026)
	40		0.70 (0.028)
	41		0.75 (0.030)
	42		0.80 (0.031)
	43		0.85 (0.033)
	44		0.90 (0.035)
	45		0.95 (0.037)
	46		1.00 (0.039)
	47		1.05 (0.041)
	48		1.10 (0.043)
	49		1.15 (0.045)
	50		1.20 (0.047)
	51		1.25 (0.049)
	52		1.30 (0.051)

[The Dark Side of Will]

The shims listed for the Muncie come in .004 intervals (or the metric equivalent).

[The Dark Side of Will]

This is interesting. I have a copy of the 282 repair manual and it says to use tool J26935. That's this tool Will sent me.

I hadn't noticed that before, but that's interesting... That might merit a call to Kent Moore and some more time on the phone with Timken. The 282 tool might have superceded the Muncie tool... strange.

I don't see any reason why the two diffs should have different preload.

Wouldn't it be so much easier if GM published the preload spec?

[Series8217]

This is interesting. I have a copy of the 282 repair manual and it says to use tool J26935. That's this tool Will sent me.

I hadn't noticed that before, but that's interesting... That might merit a call to Kent Moore and some more time on the phone with Timken. The 282 tool might have superceded the Muncie tool... strange.

I don't see any reason why the two diffs should have different preload.

When the transmission case heats up it expands and the bearings lose preload. Maybe that has something to do with it, though I don't see much of a difference in the cases to account for that being a factor.

Wouldn't it be so much easier if GM published the preload spec?

Aye..

[The Dark Side of Will]

When the transmission case heats up it expands and the bearings lose preload. Maybe that has something to do with it, though I don't see much of a difference in the cases to account for that being a factor.

Exactly... both diffs have VERY similar dimensions, are both made of the same material and both have cases made of the same material. The preload spec takes into account the differential expansion rates of the shaft and case as well as the fact that the shaft runs a little hotter than the case. The bearing cones run hotter than the cups as well (20 degrees according to Timken).

[MNFatz]

For the sake of clarity, here's a high res pic of the kent-moore tool. You can zoom in on it and read the actual instructions. Nothing about the getrag mentioned though. Not nearly as detailed as the instructions here.

[The Dark Side of Will]

A little water never hurt anything mechanical...

[Series8217]

So we've got three versions of the story for using J26935.

The largest shim that can be placed into the gap and drawn through without binding is the correct shim which should be used for reassembly.

-Determine largest shim without binding
-Use shim two sizes larger.

NOTE: The shim interval for the 282 rebuild instructions is 0.05mm or ~.002".

-Determine the largest shim that can be placed in the gap and drawn through without binding. Then use the next shim size smaller on the [...] differential for reassembly.

NOTE: the GM shim interval in the sunbird manual is apparently 0.1mm or ~.004"


Anyone else have a manual with rebuild instructions for one of these transmissions? We can't even find two sources that agree!
Also, for the Muncie shims, do they use different part numbers? The Getrag shim p/ns are sequential with a smaller shim interval.