• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)
Tips
Tips

What could be the cause?

Share this page

tr6nitjulius

tr6nitjulius

Jedi Warrior
Country flag
Offline
Ongoing issue several years and on 3rd set of rotors. Groove 1/16-1/8" deep on LH & RH rotors. Same mechanic since 1983 remains clueless as to cause. Pics of removed grooved rotor and area after prothane bush rebuild. Any clue? Thanks Julius

Clic on Link below, then Tune to Restoration, 3rd set of pics

https://videosbyjulius.com
 
Well, obviously it is rubbing on something, only part of the time. Next step, IMO, is to take things apart and find where it is rubbing (assuming you already tried changing the pads to be sure it's not a hard spot in the pads). That much cast iron gone, there has to be a very obvious mark, at least, on whatever it's rubbing against. For example, if it was hitting the trunnion somehow, there would be a corner of the trunnion worn away.

I can't really see in your photos ... is the rotor centered in the caliper with everything assembled? On the earlier TRs, the factory used shims between the caliper and its mounting bracket to center the caliper over the rotor. The shims have all gotten lost over the years (because they are a PITA to put back, even if you notice them falling out).

If you jack the car up, grab the tire at the top and bottom and try to wiggle it, can you feel any movement? If so, it may be that the wheel bearings are too loose. This is a common problem shortly after installing new felt seals, as many of the seals being sold are too thick and cause false clearance readings. Once the felt wears a bit, the bearings are too loose.

On my TR3A, I discovered that spindle itself was not round, where the inner race of the outer bearing fit. The race seemed to be a snug fit (as it should be), but the spindle was oval so the bearing was only snug on the front & back of the spindle. The result was that the race (and hence the wheel) could move up and down. That, combined with the normal flexing of the spindle under hard cornering, was enough to let the rotor hit something (I forget what offhand).
 
Are you using metallic pads? If you are, then this it is common to chew up rotors pretty fast and in various ways...

John
 
During brake job Bottom Trunnion Assembly was thoroughly inspected before & after de-grimming (grime was uniform on all of Trunnion including at what seemed to be possible touching area as well no shiny spot or worn corners visible after cleaning) Everything was apart in the shop as I had complete front suspension rebuild (grim removal, sandblast, repaint parts install, new parts, trunnions, prothane bushings, rotors etc.)

Stock calipers on 1st of two wear outs, one standard pads another with Green Pad Kevlar, Toyota calipers on most recent, groove reoccurs. The wiggle test is done prior to start of brake job (very minimal) but still chose bearing job in order to get maximum usage/even tire wear. Rotors are centered. When I say complete job that's an understatement for me as I have every related part replaced due to number of miles I drive yearly I choose to rotate wheels get alignment every 6 months change oil every 2 months or 2K miles which ever comes first, waste of money for some for me maintenance.

TR3driver said:
Well, obviously it is rubbing on something, only part of the time. Next step, IMO, is to take things apart and find where it is rubbing (assuming you already tried changing the pads to be sure it's not a hard spot in the pads). That much cast iron gone, there has to be a very obvious mark, at least, on whatever it's rubbing against. For example, if it was hitting the trunnion somehow, there would be a corner of the trunnion worn away.

I can't really see in your photos ... is the rotor centered in the caliper with everything assembled? On the earlier TRs, the factory used shims between the caliper and its mounting bracket to center the caliper over the rotor. The shims have all gotten lost over the years (because they are a PITA to put back, even if you notice them falling out).

If you jack the car up, grab the tire at the top and bottom and try to wiggle it, can you feel any movement? If so, it may be that the wheel bearings are too loose. This is a common problem shortly after installing new felt seals, as many of the seals being sold are too thick and cause false clearance readings. Once the felt wears a bit, the bearings are too loose.

On my TR3A, I discovered that spindle itself was not round, where the inner race of the outer bearing fit. The race seemed to be a snug fit (as it should be), but the spindle was oval so the bearing was only snug on the front & back of the spindle. The result was that the race (and hence the wheel) could move up and down. That, combined with the normal flexing of the spindle under hard cornering, was enough to let the rotor hit something (I forget what offhand).
Click to expand...
 
John
As stated in reply to Randall I've had standard pads, Green Pads, metallic pads now toyota the groove has occured with each set of pads. Julius
CJD said:
Are you using metallic pads? If you are, then this it is common to chew up rotors pretty fast and in various ways...

John
Click to expand...
 
I have experienced the same exact wear pattern. I have no idea what the rotor is rubbing against but I do know what the root cause is. In my case the play in the wheel hubs was too great allowing the rotor to knock the brake pistons back into the calipers causing me to have to pump the brakes in order to get the pedal to feel firm. I have never dealt with felt grease seals before getting my 6 and this is what caused all of my problems. I never adjusted the hubs properly with the technique that I have always used. So after rebuilding my calipers and installing new wheel bearings, brake rotors and pads only to have this happen again, I gave up on the felt seal and replaced them with a modern lip seal. I was then able to adjust the wheel bearing play properly and my brakes have been working great ever since and I no longer have that gouge on the inside rotor surface.
 
RomanH
Makes sense to me, believe you may have solved the issue on my upcoming visit to have rear brakes done will have felt grease seals R&R with modern lip seals on fronts. Will also share this info with mechanic in Seattle and mechanic to do brake work here in Riverside to inspect play in wheel hubs appears to be one of those issues that even a mechanic with nearly 50 yrs experience repairing British Iron has not found cause, which over the years, being my main mechanic, on my 6 he's seen & repaired numerous matters new to him due simply to it's worn out, results of the high mileage

Knowing it wasn't a result of how I drove my 6 over the 32 yrs of ownership mostly long distance drives, demanding but not hard driving, time & distance vs hard braking, autoX, locked wheel full left or right turning. Yes driven a lot of miles but never abused cruise fwy 60-70 mph max twisties 45-60 feeling it was definitely another one of those weak mechanical links in the manufacturing process but that's the beauty of owning LBC & Forums we're not alone as we continue to preserve, drive the Marque. TRIUMPH!
Julius

RomanH said:
I have experienced the same exact wear pattern. I have no idea what the rotor is rubbing against but I do know what the root cause is. In my case the play in the wheel hubs was too great allowing the rotor to knock the brake pistons back into the calipers causing me to have to pump the brakes in order to get the pedal to feel firm. I have never dealt with felt grease seals before getting my 6 and this is what caused all of my problems. I never adjusted the hubs properly with the technique that I have always used. So after rebuilding my calipers and installing new wheel bearings, brake rotors and pads only to have this happen again, I gave up on the felt seal and replaced them with a modern lip seal. I was then able to adjust the wheel bearing play properly and my brakes have been working great ever since and I no longer have that gouge on the inside rotor surface.
Click to expand...
 
I am wondering does your pad show a bump corresponding with the groove in the rotor? and does it affect your braking? As I recall when I pulled my rotors for the first time 5 years ago I think one of my rotors had a groove in it too

maybe I better check mine this weekend

Hondo
 
hondo402000 said:
I am wondering does your pad show a bump corresponding with the groove in the rotor? and does it affect your braking?

Hondo
Click to expand...

Yes, the pad shows a high spot in line with the groove that is cut in the rotor. I don't know if the high spot or groove really affect brake performance but the wobble in the hub most definitely does. Having to pump up the brakes after hitting some bumps in the road does not inspire confidence in them
 
I have not noticed on my TR6 having to pump the brakes up after hitting bumps in the road nor have I noticed having to do that in hard corning like some have stated. is there a chance the stub shaft spindles are loose or bent? I would probably see if I could get them out and check them, If the spindles are loose that could explain the deflection, having to pump the brakes and the worn groove in the rotors
Hondo
 
or maybe the front hub is worn, If the bearing seased up it could have spun the race at somepoint in time and there is too much clearance and you are getting movement in the bearing area. Had a room mate in college that had a skylark and a lot of front end wobble, took the brakes off and found out the hub was worn out and the bearing were just flopping around in the hub



just another thought

Hondo
 
Hondo in my case I was never able to set the hubs properly while using the stock felt grease seals. I thought I had all of the play out but after a few miles the hubs would be loose. I know that the felt seals have been used successfully for years but just not by me. New seals only made my problems worse since there was more felt to compress. Out of frustration I decided to dump the stock seals and replace them with lip seals and now everything is as it should be.
 
RomanH said:
Hondo in my case I was never able to set the hubs properly while using the stock felt grease seals.
Click to expand...
Which is why best practice is to find the proper adjustment <span style="font-weight: bold">before</span> installing the new felts. Mark the nut position, then install the felt and put the nut back to the marked position. The bearing might feel a little stiff at first, but the felt will quickly wear in and it will be fine.
 
As stated difficult for me with my style of driving to estimate number of miles on pads/rotors. 8/14 & 3 thousand plus miles ago while in Seattle getting complete front suspension rebuild wasn't able to get brakes pads replaced as part number for 4 piston calipers pads unknown at the time, anti-squeal pad was installed.

Today 10/19 finally rec'd & Steve Mc' installed new pads which were roughly 3/8" thick those removed had worn down to less than 1/4" on left just over 1/8" on right plus anti-squeal had partially slide off right pad 3/4" of it mangled surely must have occured during excessive heating period of brakes on smooth paved tight 45-50 miles stretch of twisties (some of the 20 mph you had to brake downshift to 15 mph, into 3rd & 3rd O/D most 30 mph, 3rd O/D & 4th 45-50mph) PCHwy1 Legget to Ft Bragg assertive braking into (occasional whiff of abestos) power out of corners due to sounds and feel upon arrival in Ft Bragg knew pads suffered some glazing were HOT! and in dire need of R&R.

Prior to R&R pads Steve asked how long ago we put these calipers on couple years my reply when I can't recall it's been too long and they're beyond replacing I'm thinking more like 3 to 4 yrs and countless miles due to this sound/feel driving relationship knew I needed brakes for a least the past year just wasn't able to hook up with Steve to get part number until now (part # on file now) Complete Front Suspension rebuild Fini! Oh and took a peek at the back side of the rotors no signs/surface wear in area of previously spoken groove, so far so good, staying on top of it as I Drive'em!

CJD said:
How many miles are you getting on the pads/rotors?
Click to expand...
 
Back
Top