Increased tire size and poor braking (1 Viewer)

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I remember I had the brake system looked at when I bought it 8 months or so back and all checked out apart from needing new rotors and pads (pads i did myself).......Will report back once i do the lspv alteration - then will go for new rotors and EBC pads - I think I'm going to live with it for the next week or two - I did a 3inch lift after a bought it as well.
its not terrible at braking but there is a noticeable difference in 'bite' - thanks for comments all - good stuff!
 
I've been dealing with the same issue. On my 92 with drums in the rear I used to be able to lock my 33s up no problem. Then my oem booster went out at 360,000 miles, a re manufactured one went out within 200 miles, and now I'm on a second re manufactured at 365,000.

All was well and then I went to 35s. I didn't think it would be that big of an effect since each tire/wheel combo was only 25lbs heavier than what my 33s and 15s weighed. Since going to 35s, my brakes just don't have much bite and seem weak.

I've adjusted the pedal to give more responsiveness right at first but it just doesn't bite in. Both new oem shoes for the rear drums and a master cylinder rebuild kit are on the way. Hopefully that fixes the problem for me. If not, I'll be looking at a rear disk conversion and bigger disks in the front.

25 Lb heavier per wheel is a HUGE amount of weight difference! Couple that with being taller and having more rotational leverage, that will REALLY tax your brakes. You need to alter your driving style to accommodate.
 
Saw you mention that in that thread but so far I had no issues and I went off-road and did some poser flex shots even. I'll take a look a closer look at it later.
It used to happen to me quite frequently, whenever the rear drooped on that side. After wheeling trips I would always have poor brakes until I realized what was going on.
 
adjust your lspv and report back, it takes 5 minutes, literally......

That is if the bolts holding it to the bracket haven't rusted solid to the lsvp valve itself :mad: BTDT...
 
25 Lb heavier per wheel is a HUGE amount of weight difference! Couple that with being taller and having more rotational leverage, that will REALLY tax your brakes. You need to alter your driving style to accommodate.

Yeah the increase in rotational mass is pretty large, but when I was going down a pretty technical descent my brakes wouldn't even hold my truck from rolling with the parking brake on which really says something. Adjusting my driving style doesn't really mean much as I always leave a pretty lengthy gap to the next car. It's just the emergency stops that are bad.
 
I was tought that every 1 lb. Of weight added to yours wheels is equal to adding 100 lbs. To your cargo. So 25 lbs added is equal to putting 2500 lbs in your 80. This is calculated by a full set of wheels (4). This is also a estimate only but has proven to be quite accurate.. . This is why ppl. 're gear when go 35's and up. It is a very very noticeable difference in performance. Turns a slow pig into a very slow pig.
 
So tried the lsvp adjustment and no real noticeable difference - going to drop it off to local tire and brake shop to give it the once over....just to be safe....
 
I run 35's on my truck and did the brakes over about 6months ago. I used hawk lt pads as others have mentioned but I also upgraded to disc brake Australia rotors all around. They have an off-road survival series rotor. They offer two levels. I have been very happy with the performance and it was a big improvement. I also pull a heavy trailer quite often. Here a link to their site. I bought everything from autoanything.com if I remember correctly. Good luck with your decision.
http://www.dbausa.com/products/4x4-survival-series/
 
Wait, the emergency brake wouldn't hold your truck on a hill, or your full on pedal pressure and your emergency brake wouldn't hold the truck? If the latter than something is wrong in your braking system.

Yeah the increase in rotational mass is pretty large, but when I was going down a pretty technical descent my brakes wouldn't even hold my truck from rolling with the parking brake on which really says something. Adjusting my driving style doesn't really mean much as I always leave a pretty lengthy gap to the next car. It's just the emergency stops that are bad.
 
Just an FYI being in Cali especially. If you remove your ABS (or LSPV possibly) then you run the risk of gross negligence in an accident you are involved in. I went thru this with my insurance agent who is a car nut himself. Insurance adjusters have started to look for brake modifications.
 
Just an FYI being in Cali especially. If you remove your ABS (or LSPV possibly) then you run the risk of gross negligence in an accident you are involved in. I went thru this with my insurance agent who is a car nut himself. Insurance adjusters have started to look for brake modifications.

thats a great point Joey, I did not know that, kinda scary.....
 
I was tought that every 1 lb. Of weight added to yours wheels is equal to adding 100 lbs. To your cargo. So 25 lbs added is equal to putting 2500 lbs in your 80. This is calculated by a full set of wheels (4). This is also a estimate only but has proven to be quite accurate.. . This is why ppl. 're gear when go 35's and up. It is a very very noticeable difference in performance. Turns a slow pig into a very slow pig.

Where did you learn that? I don't see how going from 33s to 35s could be equivalent to adding an extra 10,000lbs of cargo. I can say with certain after driving my brothers truck with 33s and then afterwards with 35s his braking performance has hardly been affected and it still stops just as quick as my mom's LX470 if not better. I get that a change in unsprung weight is not felt as much as a similar weight that adds to the sprung weight of wheels turning, but 100:1 seems kind of out there. FWIW, I have regeared to 4.88s with my 3FE since going to 35s, but that is because the larger diameter tires are in essence gearing the vehicle up and the gears are used to gear it back down to work with the factory shift points and power band.

Wait, the emergency brake wouldn't hold your truck on a hill, or your full on pedal pressure and your emergency brake wouldn't hold the truck? If the latter than something is wrong in your braking system.

The latter. I've never had braking problems until my booster went out and I went to 35s. Both were roughly at the same time. Now I'm on a third booster and planning to rebuild the master cylinder this weekend if the rebuild kit comes in which should hopefully fix the issue.
 
Just an FYI being in Cali especially. If you remove your ABS (or LSPV possibly) then you run the risk of gross negligence in an accident you are involved in. I went thru this with my insurance agent who is a car nut himself. Insurance adjusters have started to look for brake modifications.

Thanks for that info NLXTACY - ended up putting the LSVP back where it was after not feeling any real difference.....

p.s. thanks for shipping the fuse kit - hope to never need it - great little kit!
 
I went with DBA T3 rotors and EBC Green and Yellow pads, adjusted the LSPV, and my braking is enough for my liking. Especially considering I have 37s and bumpers, winch, sliders, and all the other heavy crap.
 
The same math used to calculate for gearing changes for the larger tires will work to calculate how much less braking ability you will have. Ideally you would be able to add larger diameter rotors. All the improvements in brake pads/compounds/rotors are more like making motor improvements when putting on larger tires instead of regearing.
 
Just an FYI being in Cali especially. If you remove your ABS (or LSPV possibly) then you run the risk of gross negligence in an accident you are involved in. I went thru this with my insurance agent who is a car nut himself. Insurance adjusters have started to look for brake modifications.

I have pointed this out several times in different threads. You may be accepting ALL liability in an accident if you have removed any major safety system on your rig. I have heard of fly-by-night insurance companies denying claims when they find out that seat belts were not being used.

Nag, nag, nag!
 
Just an FYI being in Cali especially. If you remove your ABS (or LSPV possibly) then you run the risk of gross negligence in an accident you are involved in. I went thru this with my insurance agent who is a car nut himself.

Yep, and it's not just Cali. A good buddy is a retired insurance exec from one of the majors, he often advises us on what is acceptable to do on our and others rigs.

His take; now days most don't even have an agent, sign up online, so they have never seen the rig, what is on your rig is on you. In these cases the policy is written by vin and they are pretty good at knowing how it is equipped. For example, on a late model '80, the list likely includes; air bags, ABS, security system, AWD, etc. These are written into the policy and a discount is given for them. This is a contract that you have agreed to, if there is a major loss and the rig isn't setup as the policy states, they can deny the claim.

His rigs are lifted, big tires, bumpers, etc, but is very selective about mods, like even questions VC removal. For example brakes; on and early FJ40 changing the drums to disk, especially using later Toyota stuff is safe. The argument is; it's bolt on later, more robust, factory stuff from a substantially similar rig, so as long as it is correctly done, would be difficult to claim that it isn't an upgrade.

Removing ABS, it will be on you to explain, make a case that it's some how safer, good luck with that. What are you going to say, I'm such a good driver that I don't need it? Not likely to fly, largely because you are there for running over/killing the bus load of nuns holding crippled kids, or whatever. They have reams of data and who do you think the court is going to accept as the expert?

Insurance adjusters have started to look for brake modifications.

It's not just brakes, any mod that maybe related to the reason for the loss. Another buddy does insurance investigation, mostly auto, and has called on me a few times for assistance, mostly 4x4 and tool stuff. Insurance companies don't want to pay claims, if they can get out of it, they will and have lots of resources.
 
Agree totally with the insurance comments, here in Spain fitting or even REMOVING a tow bar without the approval of the inspection station will result in at least a 150 euro fine but, in a worse case scenario if you have an accident without the correct papers to cover the 'modification', the insurance company will ditch you for any third party claim except for death. That comes under the same rule if you kill someone when drunk, they have to cover for that moment of stupidity.

Re the calculations, they seem to be a little off. Braking distance from speed IIRC is 'squared'? Make a wheel larger in diameter is an obvious additional 'leverage' on the brake disc/pad combo. Now add in the additional weight of the wheel/tyre combo and THEN add in the 'square' of speed means you are overtaxing the system.

Next the 80/100 brake pads, fitting the 100 brake pads increases pedal pressure to lose a given speed but, they do seem to last longer IME.

Now to the LSPV, you CANNOT adjust it my getting a lump of metal from 'Wal Mart' or whatever outlet it is you guys use, and then drilling a couple of holes and bolting it on. It has to be set with two separate and independent brake line pressure gauges....PERIOD.

The ability to lock all four wheels is NOT an indication as to the ability or power of your brakes! Braking dynamics change with how many passengers you have, whether you have a load in the back, if you are towing, how hard you are braking, how hot the brakes are prior to braking and so forth.

If (and I use the term with caution), IF you have perfect brake balance without a LSPV with four passengers, and their vacation luggage and you need to brake in an emergency and the accident is averted because your rear brakes worked without locking then fine but, if the same accident was unfolding in front of you when your passengers and their luggage have left, then you may experience rear wheel lock up. The moment a wheel (any wheel) locks you have compromised traction, this increases your stopping distance, the percentage chance of you having an accident rises.........how wide is the white STOP LINE in front of you?

regards

Dave
 

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