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#1
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Anybody know if a gasket went between the backing plate & the axle tub & also between the backing plate & the bearing retainer?
Service manual says one on the tube, but it clearly shows one on the bearing retainer as well. Not sure the purpose of either gasket to be honest, but if there is too much space in there I would think the bearing (axle) could move in/out a fuzz. could be to keep any oil that seeps past the axle seal trapped near the bearing, but that seems a little odd.
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![]() 68 GTO 4-spd Convertible 78 S/E Trans am L78, WS6 Auto 78 S/E Trans am W72, WS6 Auto 79 10th aniv W72 Trans am 80 Indy pace car Trans am 89 Trans am GTA |
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#2
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Yes, two separate gaskets. The backing plate to axle tube was a metal one 9777865 and the bearing plate gasket was a paper one 9774551. All anyone ever sells now are the paper ones to be used in both places if anyone bothers with the bearing plate one. (See #3 and #8 in diagram)
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#3
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I bought mine off rock auto , made by fel pro a few years back .
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#4
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So test fitting with a gasket on each side (I don't have the metal shims anymore)
There is to much lateral movement with the axle. .052" I used just the one gasket on the tube side & it dropped it to .025" Removed both gaskets & its pretty good. might be squeezing the bearing & plate with about .001-.002" I Really don't see the point in the gaskets anyway. Tube to the backing plate maybe to keep seeping oil on the inside of the plate, but thats about it. I think I'm going to use a little bit of sealant between them & thats it. I don't want the axles (bearings) sliding side to side. that seems like a bigger deal that gaskets. It's possible that my coats of epoxy primer & paint on the backing plates equated to the same thickness's of the original gaskets & the gaskets I have now are just too thick. Thats about the only thing I can come up with. I wouldn't think GM ever wanted lateral play. I will look in the service manual, but I don't recall any specs on that. Not sure.
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![]() 68 GTO 4-spd Convertible 78 S/E Trans am L78, WS6 Auto 78 S/E Trans am W72, WS6 Auto 79 10th aniv W72 Trans am 80 Indy pace car Trans am 89 Trans am GTA Last edited by 68ragtop; 05-26-2018 at 09:47 AM. |
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#5
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I think I might have figured out where some of the lateral play is coming from.
The bearings I installed have a fairly large radius on the edge. My guess is maybe the originals had a sharper edge? This radius allows it to slide into the tube a bit more than than it probably would otherwise. Seem probable? .
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![]() 68 GTO 4-spd Convertible 78 S/E Trans am L78, WS6 Auto 78 S/E Trans am W72, WS6 Auto 79 10th aniv W72 Trans am 80 Indy pace car Trans am 89 Trans am GTA |
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#6
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someone posted a cereal box as a gasket material (40 year ago install) like earlier this year.
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#7
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Quote:
I also realized I should have been saying "axial" movement, not lateral. in & out from the extra room created from the gaskets.Anyway, I put it together yesterday. No gaskets, but some sealant between the tubes & the backing plate. unfortunately there is still .007" of movement. but nothing like it was. Wish I would have kept the original bearings to see if those have the same radius machined into the edge of them. I'm guessing they did not. At least its not .052" like it was. that was really loose. ![]() Also, I am wondering if the original metal gaskets didn't have a small ID ? in other words it had to be installed before the bearing is pressed on. This would make sense if it is. Then it would not be creating any additional free play. If that is possible, then using a regular tube side gasket in there is only going to create problems imo. I am guessing this is often overlooked?
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![]() 68 GTO 4-spd Convertible 78 S/E Trans am L78, WS6 Auto 78 S/E Trans am W72, WS6 Auto 79 10th aniv W72 Trans am 80 Indy pace car Trans am 89 Trans am GTA Last edited by 68ragtop; 05-27-2018 at 06:30 AM. |
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#8
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HIS, curiosity was getting me so I searched & found it. it was about a paper gasket made between the axle & the brake drum.
That was an odd one.
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![]() 68 GTO 4-spd Convertible 78 S/E Trans am L78, WS6 Auto 78 S/E Trans am W72, WS6 Auto 79 10th aniv W72 Trans am 80 Indy pace car Trans am 89 Trans am GTA |
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#9
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Thought I would add a picture for clarification seeing I used the wrong movement terminology
![]() No gaskets in this picture on either side of the plate, I still have .006" "axial" movement. (bearing sliding in the tube) Would love to have zero, but its close & waaaay better than were it was. .
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![]() 68 GTO 4-spd Convertible 78 S/E Trans am L78, WS6 Auto 78 S/E Trans am W72, WS6 Auto 79 10th aniv W72 Trans am 80 Indy pace car Trans am 89 Trans am GTA |
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#10
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Bearings have endplay rigjt?
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#11
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The old service manual allows for up to 0.032" before bearing replacement was needed.
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1968 Pontiac GTO - Verdoro over Ivy Gold - 400/4-speed/3.08 1987 Pontiac Grand Prix - Sage/Sage/Sage - GM 305/Th200-4r 2004 Pontiac GTO - IBM over Black - LSx 440/6-speed/4.10 SRA - Single Digit Stick Shift |
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