Some 15s do clear the 93+ front brakes, my 2-piece Weds do for example. Also, i'd highly recommend speed bleeders for ease of bleeding solo - Russell speed bleeder part # 639560
HDJ81 Brake Upgrade - With Part #s and Pics (1 Viewer)
- Thread starter Adam B
- Start date
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Having a hard time finding backing plates. Can I run without them?
Yes but you need a spacer or just cut the bolt pattern out of the backing plate and in stall it. That's what I did worked fine.
The bigger rotors appear to fit the backing plates already installed. Does this look right? 1991 HDJ81 JDM. Thanks guys!
Those are 93 through 97 rotors? I got 97 rotors and my plates were to small
Sooo....this truck keeps surprising me. Looks like the truck had the bigger brakes, probably modded by the PO in Japan. The last shop I took it to put on small rotors and maybe the bigger pads? It’s a s*** show and caused a caliper to fail. Glad I’m starting fresh with new calipers and rotors and looks like I already have the bigger backing plates....
Cool yeah mine was bone stock everything is new now. Keep in touch brother
Hey so front brakes in HDJ81s are mediocre and need to be upgraded but how are the rear disc brakes? Are the rears bigger for 93-97s as well?
HDJ81 Rear Disc Brake Upgrade
I am looking at swapping my rear discs (I've already done the front) to the larger North American 80's rotors. I believe its the 1993-97 I am after. Mostly swapping the rears for parts availability as I dont think their is much of a performance gain to be had. From what I can find on the forum I...
forum.ih8mud.com
I have just done this mod, very nice and brakes crazy well now. No ABS but haven not skidded yet....
Dave 2000
Not all Land Rovers are useless!
@Adam B
Nice information and write up, it was a few years ago I replaced everything with stock size discs and calipers, although the discs all round are dimpled and grooved, discs that are cross drilled are of no use off road.
Whilst I find the braking adequate for a manual shift 80 and doubt I might do them again, but if I do I will go that route, although as a mechanic I have to ask were/are there any issues with the master cylinder and or brake balance front and rear?
Regards
Dave
Nice information and write up, it was a few years ago I replaced everything with stock size discs and calipers, although the discs all round are dimpled and grooved, discs that are cross drilled are of no use off road.
Whilst I find the braking adequate for a manual shift 80 and doubt I might do them again, but if I do I will go that route, although as a mechanic I have to ask were/are there any issues with the master cylinder and or brake balance front and rear?
Regards
Dave
The issue with brake bias is more to do with the lspv in the rear of the truck. If you have lifted your truck it messes it up.
Dave 2000
Not all Land Rovers are useless!
No I understand that, I am saying what if with the bigger brake modification you are braking more with the new front brakes because they are more efficient, then the rear brakes would not be used so much, that is the new more powerful brakes are doing all or more of the work instead of the more accepted 70/30....ish bias. perhaps throwing away some of the effort given to the overall stopping power applied to all four wheels.
Forgive me if I am not making myself clear, I have not been out of hospital long and am still recovering from the removal of a brain tumour.
Regards
Dave
Bama4door
Supporting Vendor
Just did this upgrade for the front while rebuilding the knuckles w/ new WB's. Thanks for parts info in this thread.
Oh wow that’s horrible. So sorry to hear that, I hope it went okay for you.
I get what you mean but I think the pressure would be the same as the same hydraulic cylinder is working bigger pistons. It may do the opposite as it’s like a Venturi effect. The bigger the orifice the lower the pressure with the same producing power.
I think common sense wise you will use more front as there is more front available for stopping power but I am not a brake expert.
Dave 2000
Not all Land Rovers are useless!
Thanks, recovery has been slow (Diabetic for 30 years hindering healing) but tomorrow I go to the hospital to complete some cognitive and reaction tests to see if I can get my driving privileges reinstated, it's been a long road to recovery but reckon I am close.
Back to the brakes.
My point is, brakes are designed size and bias wise to the front and of course the rear have to contribute some tractive effort the whole point of having four wheel brakes. If the brakes at the front are 'better' then surely there would be less effort from the rears? Putting it another way, the bias valve at the rear under heavy braking reduces the effort to the rear brakes to prevent lock up as the front dips and the rear rises, that is the body moves up away from the axle, if the vehicle is loaded the rear lifts less under the same amount of braking effort, Now if you increase the front braking effort with the bigger front brakes then the rear would lift higher reducing the effort applied to them, the result is the front brakes are now doing all of the work. I supposes the way to go would be to drive the car and make a few repeated gentle braking stops to warm the discs up, then point a temp gun at the front and rear discs and get some readings?
It might be worthwhile after doing the gentle stops and getting the readings, then doing some hard stops (on tarmac) and see if the ABS kicks in, if the ABS has been removed (don't start me off) have someone standing at a safe distance to see if the fronts lock and the rears don't. If the rears do lock then you have a dangerous car, if they don't but you did get some reasonable temperatures at the rear in the earlier test then you at least know they are contributing to the overall braking effort.
I hope that made some sense?
Regards
Dave
TheMU
SILVER Star
Hey @Dave 2000 , thanks for the info. Just swapped over to the bigger brakes.
Stopping is better. But pedal feel is weird. The first time I press the pedal it goes down and then afterwards it doesnt. So I'm thinking I have air in the system.
I also upgraded the outer halves of the birfields to the 30 spline and got the deeper Axle Hubs.
The shields I didnt cut but bent over to see if it would work.
I'm using with 15s but they have -20mm off set. They barely clear.
I have matching spare, and wheels so not sure I want to change. So might go with spacers.
Stopping is better. But pedal feel is weird. The first time I press the pedal it goes down and then afterwards it doesnt. So I'm thinking I have air in the system.
I also upgraded the outer halves of the birfields to the 30 spline and got the deeper Axle Hubs.
The shields I didnt cut but bent over to see if it would work.
I'm using with 15s but they have -20mm off set. They barely clear.
I have matching spare, and wheels so not sure I want to change. So might go with spacers.
Dave 2000
Not all Land Rovers are useless!
If you get a low pedal and then a second press makes the pedal feel fine then check your wheel bearings all round. In the trade we call this 'pad knock off'. Basically as you drive a loose wheel bearing allows the discs to push the pads back into the calipers, the first press of the brake pedal puts the pads back where they belong but results in a low pedal, the second press the brake pedal travels less because the pads are where they are supposed to be. Try getting the pedal up to where it feels good and then drive the car and steer left to right a few times and then check to see if the pedal has gone low again on the first press, 80% of the time it is the wheel bearings, the other 20% could be air, a failing vacuum servo (or the back up reservoir as you have the diesel), or perhaps a caliper piston sticking?
Regards
Dave
Regards
Dave
TheMU
SILVER Star
Thanks for getting back to me Dave.
Would this happen with new wheel bearings as well?
I'll do the test that you mentioned and report back. Once I pump the brake the brakes work better than they were.
For context, OEM Rotors, Calipers, SS Brake Line to Axle. Birf Rebuild.
Still the original brake booster.
