[curtis73]

Car is a 67 Lemans convertible, 326, 4 wheel manual drums. I just bought the car and the brakes were terrible, so I pulled them all apart to see what was going on. Replaced two frozen wheel cylinders, made some adjustments, new master (and a power booster while I was at it). The bearings looked ok, but plenty old and pretty dry, so I got new bearings and seals. Here's where it gets funky. The one front drum has the typical 2.33" seal bore. The other one has a 2.4" bore like found with disc hubs. I even cross referenced the number on the old seal and its for a disc application. Any ideas why?

So I thought; no worries, I'll just get one disc seal and one drum seal. The problem is, the drum seal (tried 3 different ones) bottoms out on the bearing before its seated. I thought maybe the race wasn't driven in the whole way, but its seated. I'm darn close to just buying new drums but I'm not sure it will fix the issue.

Which brings up the next question. I've spent way too long trying to fix up drum brakes and I'm tempted to get some factory discs for now. Will factory A-body 11" discs fit behind the stock rally-type 14" wheels?

[curtis73]

A little more information...

The "correct" hub is casting 35565-R. The other hub is casting 35734-R. The seals I'm using are 8705S for the bigger hub, and 8121S for the "correct" hub.

I went through and did a comprehensive comparison of part numbers, visual inspections, etc. The races and bearings are correct. The spindles all spec out the same.

Bolted everything back together and found that the 8121 seal is so tight on the spindle that the drum barely turns. That would also explain why the seal I took off that side was completely toast. Both spindles' seal surface is 1.75" exactly.

Does anyone have any ideas what the &$*#&# is going on?

[rexs73gto]

Sounds like it's time for the disc brakes on the front end to solve the problem. The factory 11 inch rotors will fit if you have the correct Ralley II's for disc brakes. There are different rims for drums & disc.

[curtis73]

Ok. As long as I'm changing wheels to get discs I might just go ahead with 17s and do 12" LS1 rotors. All I wanted to do was tune up the factory drums and get it on the road and its fighting with me.

Its one of those things that can't happen but it is. The seal is right, the spindle is right, the bearings and races are right, the drum is right... but it doesn't fit. So frustrating.

[Scarebird]

Originally Posted by curtis73

Ok. As long as I'm changing wheels to get discs I might just go ahead with 17s and do 12" LS1 rotors. All I wanted to do was tune up the factory drums and get it on the road and its fighting with me.

Its one of those things that can't happen but it is. The seal is right, the spindle is right, the bearings and races are right, the drum is right... but it doesn't fit. So frustrating.

Drum hubs are often different between Pontiac, Olds etc. and you may have different models on your car. Seal bore may be different too...

[curtis73]

Originally Posted by Scarebird

Drum hubs are often different between Pontiac, Olds etc. and you may have different models on your car. Seal bore may be different too...

Yeah... looks like the "incorrect" hub is from a camaro. Everything is exactly the same except where the seal presses into the hub. After some deep searching, I came up with this:

2.33" seal bore was used for drum pontiac, therefore taking an 8121 seal (and others, but for the sake of this application, I'm just listing the pontiac)

2.4" seal bore was used on disc pontiac, and both disc and drum camaro, therefore taking an 8705 seal

Spindles for the two spec out identically, as do bearings, so they are interchangeable as long as you use the right seal.

Here is a new fun one to figure out though. When I pulled the Pontiac drum off, the seal was completely wasted. Didn't give it much thought, but now that I put the new correct pontiac drum seal on it (8121), it is super tight on the spindle. I verified 1.75" spindle bore where the seal goes. I verified that the seal is 1.73" (both by the parts catalog and direct measurement). If I leave the seal off, the drum goes on and spins normally. If I put the seal on, the rubber is super tight on the spindle. I verified that its going all the way on to the seal journal (smeared some grease, assembled, disassembled). Just super tight. I'm afraid its going to burn up like the last one.

I actually tried four different 8121 seals from three different sources; Timken, duralast, napa. Just a curiosity. The spindle specs out right, the seal is right... just really tight.

Adventures with chinese parts? Something I'm missing?