• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Brake drums

Share this page

Wana

Wana

Jedi Hopeful
Offline
I just had new wire wheels, tires and hubs put on my '66 BJ8. I was hoping very much that this would eliminate my shaking at 55-60 mph, but alas it hasn't. It is some better, but still noticeably there.

I had read here and elsewhere that the brake drums can be quite a bit out of balance and can cause or contribute to the shaking.

I removed my right rear brake drum as it feels like that is where most of the shaking is coming from, and sure enough its inner wall appears to be quite a bit off center (the rim is much thicker on one side than the other).

I called around to machine shops in my town and nobody will even look at it. I know that Hendrix Wire Wheel in NC provides drum balancing, but I live over a thousand miles from them.

I'm wondering if anyone has purchased the newly manufactured drums from the major Healey parts suppliers, and if so what you thought about them and are they balanced?

Thanks!
 
Hi Wanna,Question ;How were the tires and wheels balanced that you put on the car???---Keoke
 
Keoke, I got them from British Wire Wheel. They told me that they trued and balanced them before they shipped them to me.
 
OK Wanna, However, most cases the front wheels must be Spin Ballanced on the car.---Keoke
 
Hi Wana,
If your drums look like the attached pic, it would be well to have them corrected. Sending them to Hendrix would assure that it was done properly. It's not really so far away from you in this day & age.

I have also had tires & wheels balanced by Hendrix (off the car) & they were perfectly smooth.
D
 

Attachments

  • 117049-Brakedrum.jpg
    117049-Brakedrum.jpg
    107.6 KB · Views: 171
Hi Dave,

Yes, they look exactly like that. Do you know if Hendrix machines the drums or do they just spin them and add weight? Alternatively, do you know anything about the new replacement drums that all of the Healey parts suppliers sell? If I am paying Hendrix $75 per drum plus shipping plus downtime, seems to me new drums at $89.95 might be a better way to go if they are good quality and balanced?
 
I'm not sure how Hendrix balances the drums. It could be adding weight to the light side. If needed, I would be tempted to center the hub hole in a lathe & skim the outer drum circumference to true with the center. As is, there must be variation of the outer drum thickness, since the indexing point for machining the shoe surface was likely the off center hole as first machined in the casting. The off center machining may only be a problem with the later cars. My original BN2 drums, front & rear, are so close as is, that they didn't need any work.

I have no idea about the quality of the $89.95 drums. I do know that high quality drums cost about twice that much.

I'm really surprised that you can't find a shop with a 14" or larger lathe, to chuck up on the center hole & skim the outer circumference to true with the center. The inner shoe surface has already been trued to the off center hole during original manufacture.

You could even set the drums on a bubble balancer & add/remove metal as needed to balance. It would likely help a lot.

Several possibilities,
D
 
Success! I decided to start with the simplest thing first - have the wheels and tires double checked to make sure they were indeed correctly balanced. They weren't! One of the wheels was 2 oz. off, the rest were within 1/2 oz. He balanced them all perfectly and my Healey now rides smooth as silk! I took it up to 75 mph and got no vibration all the way up. I am soooo happy!

However, I am a little confused now by the brake drums. Since they are visually off-center how can they have no effect on the ride? Oh well, I'm just glad I didn't spend a bunch of time and money chasing this one and feel lucky that it appears to have just been the wheel/tire balancing that was needed.
 
[ QUOTE ]
Success!
However, I am a little confused now by the brake drums. Since they are visually off-center how can they have no effect on the ride? Oh well, I'm just glad I didn't spend a bunch of time and money chasing this one and feel lucky that it appears to have just been the wheel/tire balancing that was needed.

[/ QUOTE ]
Very glad you found the problem. The drums are at a considerably less radius from the rotation center than the tires/wheel rims. This means that drum imbalance would have less effect than wheel/tire imbalance. Apparently your drums are not far enough off center, for the speeds you are driving, to cause a problem. Drums are usually checked as a last resort after wheel & tire balance are corrected. It is usually most noticeable at higher speeds.
D
 
See Wanna! I told you to check em!---Keoke /ubbthreads/images/graemlins/yesnod.gif /ubbthreads/images/graemlins/laugh.gif

OK! Wanna, here is another tip,Jack up each front wheel and remove the Knock off, using a chisel make aligned light indentation on the wheel hub and the spline hub.Put the knock off back on and do the other one . Now when you remove the wheels for cleaning you can reinstall them in their ballanced location--FWIW---Keoke /ubbthreads/images/graemlins/driving.gif

Don't be confused about the brake drum problem.Dave has explained its virtual no effect because of the short radiuses and smaller mass involved.
 
Good day, Wana! Hey, I am really happy for you that you were able to solve the dreaded 55mph shake! I do have a question, though: How did you have your tires/wheels balanced that solved the problem? I am interested in the balancing method used and the shop that did it. Many thanks,
 
Hi Steve, There are other causes for scuttle shake. However, A tire shop should be available in your area that can do "On The Car Wheel Balancing",If this is the cause you will see the shake being tuned out during the procedure. Wheel speeds can be simulated over the entire speed range of the car.Check with some of the Texas clubs and see if they know of a source.---Fwiw---Keoke
 
Stever - I took them in to the only tire place in my city that knows wire wheels and has a guy there that seems to have "the knack" for balancing them correctly. I'm afraid I don't know how he does it, but I do believe they are done off the car with some sort of balancer machine. Sorry I don't have more details. Wana
 
Don't know if this applies to your situation, but while attempting to adjust the brake shoes on my BN6, I noted that the shoes make inconsistent contact with the drum...which suggests to me that the shoes and drums are not concentric (or more precisely, the drums need to be turned). Therefore it is necessary to back off the adjustment to the point where there is no contact on the "high side" of the drum...which I believe results in excessive pedal travel? Perhaps someone can correct me if I'm wrong.
 
The drum shoe surfaces were alledgedly hardened at the factory to reduce wear. Grinding them will remove this hard surface & they may wear faster. A compromise adjustment of light rub at one spot works pretty well. You could replace the drums or have them reground or live with it. If you only drive a few miles per year, you would not notice the reduced drum life that results from regrinding.

My 50 year old drums have a bit of out-of-round but show absolutely no wear. Actually, they seem to become more round as they heat up under heavy braking.

You can be the judge,
D
 
While on the subject of original cast iron parts, i once looked at getting a 100 head cast to original specs, would i be in breach of patent?, same would i guess apply to getting drums cast?
 
There are a couple of cast aluminum heads on the aftermarket. DWR UK has a very good one that fits as original, has much improved internal port shapes, & revised cross sections to strengthen the original weak areas. It has the same external casting numbers as original & shows the original patent numbers. They also have some high quality brake drums. See attached head pic;
D
 

Attachments

  • 118062-DWRhead.jpg
    118062-DWRhead.jpg
    83.5 KB · Views: 123
Back
Top