FZJ80 axle swap into Land Rover

[Mattmannz]

Hard to decide which forum this should go into.

I am using late 80 series axles under a Discovery 1. No abs.

Have a single flexi line servicing each axle, new lines, pads, rotors, calipers etc. Stock Rover master cylinder.

I have a hard pedal but as soon as the motor runs I lose pedal. I can't hold the vehicle back with the pedal.

Anyone have any thoughts? Is my Land Rover master cylinder too small?

Cheers
Matt.

 

[inkpot]

Hard to decide which forum this should go into.

I am using late 80 series axles under a Discovery 1. No abs.

Have a single flexi line servicing each axle, new lines, pads, rotors, calipers etc. Stock Rover master cylinder.

I have a hard pedal but as soon as the motor runs I lose pedal. I can't hold the vehicle back with the pedal.

Anyone have any thoughts? Is my Land Rover master cylinder too small?

Cheers
Matt.

Does your engine have forced induction? Is the vacuum operated brake booster getting pressure instead?

 

[Mattmannz]

Does your engine have forced induction? Is the vacuum operated brake booster getting pressure instead?

Sorry I should have said, it's just a 3.9 V8 so no boost there, definitely vacuum. Thanks for your reply.

Cheers
Matt.

 

[Cruiserdrew]

Hard to know. It sounds like your MC doesn't move enough fluid to activate the brakes. I assume it's been bled correctly and there isn't air in the system? How different in physical size is the 80 MC vs the D1 MC? That will at least give a clue.

 

[bmwjnky]

Master cylinder probably isn't matched right for the volume of the 80 series calipers if you had no brake issues before this conversion. I don't know how to do the math but I'm sure there are online calculators that will tell you what size master cylinder matches the 80 series caliper piston and caliper volume.

 

[Mattmannz]

Hard to know. It sounds like your MC doesn't move enough fluid to activate the brakes. I assume it's been bled correctly and there isn't air in the system? How different in physical size is the 80 MC vs the D1 MC? That will at least give a clue.

Master cylinder is a 1in bore, same as the Toyota one. Note sure about stroke length.

 

[ppc]

My guess is that the seals inside the master cylinder got damaged during the process of bleeding. When the travel of the seals goes beyond the normal range there can be grit that damage the aged seals.

Did the previous front calipers also have the same 4 piston configuration as the 80's?

 

[canman]

Suspect that air is still in the system or getting in. Did you bleed the master cylinder? Does the Rover have a LSPV? Are all fittings tight?

 

[duggy]

In stock configuration, the 80 axle uses 2 lines coming from the MC to service the 2 calipers up front. I don't know if this matters, but something to keep in mind.

 

[LandCruiserPhil]

A local guy did the same conversion years back here on mud maybe a search will give you some info

 

[mod5csi]

Suspect that air is still in the system or getting in. Did you bleed the master cylinder? Does the Rover have a LSPV? Are all fittings tight?

If the MC was good before, and it's nearly the same size air seems plausible.

A buddy and I looked into this on his D1. I know there's swap threads on the LR forums.

 

[Mattmannz]

Thanks for all the replies, appreciated.

The early 80's without ABS don't have dual front lines, they have a single. I have used the original T fitting on the diff. All the fittings and lines and hoses are tight and not leaking anywhere.

There is no LSPV fitted currently, I will need to get an adjustable unit as the Toyota rear brakes are a lot bigger than the Rover units.

The brakes were fine before, pretty sure itthe stock brakes were four piston front, not as big though as the Toyota fronts.

I have bled about 300mls out of the system, I could probably continue to bleed it further. Might throw a new master cylinder at it, have done nearly everything new now anyway.

 

[ThreeEyedBandit]

How does the pedal feel with the engine running? If the master cylinder is approx the same size then you have either damaged it(mentioned above), have a leaky wheel cylinder or have not bled enough(300ml is borderline on bleeding it fully).

Pedal feel with the engine running will help diagnose the problem. Is it spongy(bleed more), firm but not solid(fluid passing by a seal), overly stiff(booster problem/mc too big/vacuum problem)?

 

[Mattmannz]

Firm but not solid. Definitely no leaks but possible that it needs a bit more bleeding.

Have a new TRW master cylinder on the way so will fit that and rebleed and that should sort it.

 

[jkdowty]

The early 80's without ABS don't have dual front lines, they have a single.

I have a '91 fj80 (First year for the 80) no ABS and have one line on each caliper coming directly off of the MC...

 

[Hornd]

I highly doubt Toyota would use 1 line to feed both calipers.
That eliminates any redundancy in the Most important safety item on a vehicle.
I have been wrong before.

 

[jkdowty]

I highly doubt Toyota would use 1 line to feed both calipers.
That eliminates any redundancy in the Most important safety item on a vehicle.
I have been wrong before.

the front has 1 coming of the MC going to the front left and another coming off mc going front right... The rear has one coming off the LSPV going to a "T" fitting then splits to each side...

 

[jfz80]

i recall a couple older threads... here is one of them missing some pics now and doesnt address the brakes.
1997 FZJ80 Axles Meet 2000 Land Rover Discovery2
Maybe you could pm @Discyota and see if he gets an email. He hasnt been around since 2011
might have the same username on pirate though

 

[alia176]

I have nothing to contribute except "where are the damn pics of this abomination, err, I mean hybridization bastard?"

 

[Mattmannz]

Thanks for all the replies.

The front axle I got definitely only has one flexible line to the chassis which has a T piece on the diff with hardlines running out to the knuckle where flexible lines connect to the calipers.

Perhaps I need to research this more and redesign it to use dual lines direct to the calipers.