'70 F85

I just replaced one of my front drums on my F85 without pressing the studs out, consequently, I did not press the studs into the new drum. My question is, do the drums absolutely have to be pressed fully onto the studs? Like all the way down to the part that has tooth like groves on it? I ask because I am feeling a bit of slip when I drive, turn to the left, and stop. I think I know the answer, I just want to be sure.

joe_padavano

If the old drum came off without pressing the studs out, then the new one went back on the same way. Some of these drums used studs with a longer knurl that pressed into the drum, some did not and thus the drum slips right off. Properly torquing the wheel lugs would have fully seated the drum in any case. The "slippage" is in your mind, I'm afraid. In any case, it isn't caused by this issue.

'70 F85

1. I have a long knurl, and it comes through the hub face. It took over three hours and a ton of penetrating fluid to get the drum off. There was no "slipping right off" involved.
2. My old drum had no space between the outward face of the drum and the studs, the new one has a gap around each stud about the size of the knurling.
3. What I am feeling is undeniable.

joe_padavano

In that case, I would not have thought it possible to remove the drum without pressing the studs out. How hard did you have to beat the crap out of it to get it off? Any chance you bent the hub in the process? For future reference, in situations where the studs press into the drum, press the studs out FIRST. Note that you don't even need a press to do this - a two pound sledge works. Support each stud in turn from the underside with a sufficiently large socket or length of pipe, thread a lug nut onto the stud so that you are hitting the nut and not the stud threads, and wail away.

Are you saying that the new drum has oversize holes that are too large to engage the knurling anyway? If so, the pressing is irrelevant. And again, if the wheel nuts are properly torqued, this is a non-issue. I've had A-bodies with similar "loose" drums with no noticeable effects.

Maybe, but it is still unrelated to the drum. If you really think the new drum is causing this, then swap the front drums and hubs side-for-side and see if the issue occurs on the other side now.

Allan R

Joe, I think what the OP is saying is that he didn't seat his new studs into the drum. Otherwise there would not be the gap he's describing. And that would also be symptomatic of his driving experience. What he COULD do is overtighten the nuts on the wheels to pull the new studs into position.

joe_padavano

OK, that's a possibility, but not how I interpreted what he wrote. To me a "gap around the studs" sounds like the holes in the drum are oversize, but I can now see your interpretation as well. This is a classic example of a picture being worth a thousand words. Of course, if the latter is the case, flip the drum over and you should be able to see a gap between the hub and the drum, which would obviously be incorrect.

Back to my previous post - the only way to do this right is to press the studs out of the hub, properly seat and support the drum on the hub, and press the studs back in one at a time. Again, use a socket or tube over each stud in succession as a support while pressing the studs back in to avoid warpage or distortion. Trying to press the drum over all five studs at once is just asking to warp the drum.

'70 F85

Thank you for your help. I am going to take it to a shop and press them correctly.

Allan R

Joe, I agree a pic would have been best. I'm really curious what really happened there. I know when I did the new studs on my rotors I just smacked the old ones out because I wasn't keeping them. I used some nylon bushings and a metal flat washer as spacers when I pulled the new studs through using a long handled wrench. They seated nicely. Prior to pulling them through they did have that gap as op described.
That must have created on heck of a drivability issue and I'm surprised he didn't get steering wobble like a bent wheel.

joe_padavano

I'd like to know how he got the drum off without pressing the studs out first.

'70 F85

Used the original tire iron and pried using the backing plate. Dumb idea, I know. Had to go back and hammer the backing plate flat once I got everything off. Whole job took 13 hours for one front drum. Thanks again. I know next time to post pictures as well.

joe_padavano

Wow.

I would check the hub for runout before pressing the new drum in place. I would also check the new drum to see if it got bent when the wheel nuts were torqued. And definitely double check the backing plate - if it isn't correctly parallel to the hub wheel mounting surface, the shoes may not sit correctly in the drum.

I also suggest you get yourself a Chassis Service Manual before resorting to brute force again. The collateral damage can be far reaching.

svnt442

And remember that these cars were made to be serviced. If you find that something seems to be overly difficult, there is a good chance that there is a better way to do it.

Allan R

Truer words never spoken.

Which is exactly why the CSM is your best friend. With just a quick glance through my 72 CSM (section 5) my first thought about how hard it was for the OP to get his drum off was: Did he back off the adjuster before attempting this? If not, it might be very difficult to get the drums past ridges likely developed at the edges of the shoes. I used my CSM to full advantage when I did my rear drums years ago. I also found that the rear backing plate on my car was not only original, but the adjuster slot had never been punched out. Fortunately the drums didn't put up a fight coming off. They went for machining since there was lots of meat left and all new components installed. Never did punch out the adjuster slot on the backing plate, but I inspect them annually anyway.