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Discussion Starter #1
Hi,
I have a couple of items that I am unsure about. First - my car is a 1990 Geo Tracker with 67K original miles. It is 4x4 and 5 speed, no lift or alterations. A very clean very stock car with original paint and original interior. Tires are 235/75 R15 BFG A/T.

Power Brakes - the pedal effort seems too high, and I practically have to stand on the pedal to get even a bit of lockup. I can feel the power booster working as the pedal height changes with the engine off. Pedal effort reminds me of my old Honda 600 sedan that had similar pedal effort. Is this normal? I have not driven any other cars so nothing to compare to. I also have redone the front brakes (new rotors, rebuilt the calipers, new mounting hardware), and the rear brakes are functioning normally with no leaks, etc.

Driveshaft vibes - I am getting a vibration at about 45mph. Does not matter what gear I am in, or whether I am accelerating, decelerating, or maintaining speed. I initially thought the spline might be worn on the driveshaft and purchased another spline part (goes into txfr case). Both splines have a similar amount of play. When the driveshaft is installed - I get about 1mm (.040") play up/down at the u-joint at the output to the rear axle at the transfer case u-joint. This is more than double what I get at the front driveshaft and both use the same construction. I am now thinking the the roller bearing in the txfr case rear housing behind the seal may be the issue. I would appreciate any feedback on this before I start ripping into something else...

Also, is there a trans shop familiar with these vehicles in Orange County, California? I have a messed up shoulder and doing the transfer case rear housing R&R would not feel very good right now...

Sorry for the novel, and thanks for any help with the above issues.
Doug
 

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In searching through the forum, I find that you’ve had a thread regarding some of these issues already.
https://www.suzuki-forums.com/suzuki-sidekick-escudo-vitara-geo-x/264533-need-slip-yoke.html
By the way, I have the 1991 Tracker, and have had 67K miles twice on my odometer, and am heading for a 3rd time. Anyway, hoping your’s is legit.
No, what you are feeling in the brakes is not normal. When you’re talking about ‘lock up’ are you talking about the rears? Give some more info as to what you mean. Superficially, if you’re talking about the rears, it sounds like you have an obstruction in the pipes going to the rear brakes, or something amiss with the booster. This car should stop really well, with little effort at the pedal.
There should be no play at the U-joints up and down. Have you checked the balance in the rear tires? Where do you feel the vibration, or is it something that you hear rather than feel??? For example, an increase in exhaust backpressure due to an exhaust obstruction at a certain rpm can cause a audio vibration at a particular rpm
 

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Discussion Starter #3
Bex,
Thanks for the response. Miles are legit - original owner bought as first car and did not want to part with it - it was just stored in the garage for years. Original paint and clearcoat are in great glossy shape except for bumpers.
Regarding the brakes - The fronts are 100% new and I had no trouble bleeding them so no restrictions there. At the rear - it looks like the drivers side front piston may be frozen causing the front shoe to drag slightly - I have new slave cylinders on order and will do them this weekend. So far I have not had any issues with brakes seeming stuck - just a high pedal effort. I can get the brakes to start to lock the tires with effort but it seems higher than it should be. No pulling or other bad manners, and e-brake works well and will lock rears. Power booster is functioning as the pedal is lower and effort is less with motor running, but may not be at 100%?

Regarding the vibration - It has to be at the driveshaft as the frequency is too high for it to be tires. Tires are less than 1 year old and all weights are there. I hear it more than feel it - maybe just a slight buzz in the shifter. I ordered new txfr case gaskets and bearings so I can get the roller bearing in the tailshaft replaced as that may be the source of looseness at the slip yoke. The front slip yoke will barely move while the rear will move at least 1mm. Exhaust looks correct and original and no funny noises or restrictions. U-joints felt smooth, move easy with no play so not coming from there.
Thanks!
Doug
 

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Have you considered the disk pads you have fitted as a possible cause? I'm currently running EBC GreenStuff on my vehicle, and these require noticeably more pedal pressure than the previous pads.
 

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Discussion Starter #5
I am running new rotors with top line Centric pads which have worked well for me on other vehicles.
 

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You seem to indicate that you just bled the front brakes? Is that correct? Normally they are bled from the rear, starting at the left rear. What braking system do you have - the RWAL or LSPV??
The ‘vibration’ you talk about - it’s something that you hear, but not feel? Are you sure that it’s not a slight exhaust obstruction that would make a noise at a specific RPM in all gears due to the backpressure?
 

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Discussion Starter #7
You seem to indicate that you just bled the front brakes? Is that correct? Normally they are bled from the rear, starting at the left rear. What braking system do you have - the RWAL or LSPV??

The ‘vibration’ you talk about - it’s something that you hear, but not feel? Are you sure that it’s not a slight exhaust obstruction that would make a noise at a specific RPM in all gears due to the backpressure?
I don't know what RWAL or LSPV stand for. I blocked the brake pedal partway down when I removed the calipers so no air could enter the master. Then I only have to bleed the front as only small air pocket in the front lines. Works wonderful and Dave's work.

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I don't know what RWAL or LSPV stand for. I blocked the brake pedal partway down when I removed the calipers so no air could enter the master. Then I only have to bleed the front as only small air pocket in the front lines. Works wonderful and Dave's work.

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aha, i see a problem. what do you mean by "block the pedal part way down?
I wonder if you have damaged the master cylinder and this is where the issues are.

Please describe exactly what you did and in what order.

Its easy to stop air getting into the master cyl, remove cap, fill with fluid, plastic bag across top, refit cap. you can remove brake hoses like this and then bleed all 4 corners regardless of which hose you had off.
 

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Discussion Starter #9
No problem with the master cyl. I just pressed brake pedal part way down and blocked it so an open line can't drain the reservoir. The Piston blocks the path so no master bleeding is required.

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Discussion Starter #10
I believe RWAL is rear wheel antilock and I don't have that. Just the valve that senses load at the rear axle.

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No problem with the master cyl. I just pressed brake pedal part way down and blocked it so an open line can't drain the reservoir. The Piston blocks the path so no master bleeding is required.

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what you have done can also jam one piston in the master cylinder. These have 2 separate pistons, one for each 1/2 of the braking circuit.
The Lines will still bleed and drain fluid from the tank as the return valve in the master cylinder will allow fluid to flow into the brake circuit, but not from the circuit to the master cylinder when the pedal is pressed, this is how its designed to work so additional fluid is added to compensate for pad wear withouit the pedal sinking over time.
Fluid can still flow from reservoir into brake circuit if pressure in circuit is lower than the head pressure in the reservoir, such as opening a bleed nipple.
What you have done is pointless and could have actually caused one half of the master cylinder to jam reducing braking to minimal effect and a hard pedal

Bleed all 4 corners using the "press and hold, open nipple till pedal sinks, close nipple, release" method and see if it comes right, (2 people required) I suspect the front section of the master cylinder is stuck and bleeding will solve the issue. When you crack a bleed nipple on the affected section you may hear a "click" as the piston returns to its correct position.
 

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Discussion Starter #12
You seem to indicate that you just bled the front brakes? Is that correct? Normally they are bled from the rear, starting at the left rear. What braking system do you have - the RWAL or LSPV??
The ‘vibration’ you talk about - it’s something that you hear, but not feel? Are you sure that it’s not a slight exhaust obstruction that would make a noise at a specific RPM in all gears due to the backpressure?
Bex,
I believe the vibration is driveline related as it is speed related, not RPM related. I only get the drive line vibration at 45mph range and it does not change with engine rpm (same in 3rd, 4th, 5th gears). I think it has to be the play at the slip yoke as 1mm movement is quite a bit for a driveshaft - especially with the gearing on these cars...
 

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Bex,
I believe the vibration is driveline related as it is speed related, not RPM related. I only get the drive line vibration at 45mph range and it does not change with engine rpm (same in 3rd, 4th, 5th gears). I think it has to be the play at the slip yoke as 1mm movement is quite a bit for a driveshaft - especially with the gearing on these cars...
I'd check rear tyre balance also, that can cause what feels like a driveline vibration as well. Even tho wheel weights are there, tyres do change weight balance over time. People often don't balance the rears properly either.

Quick way to prove it, swap fronts and rears same side and see if it goes away.

I agree, doing the rear output bearing is sensible if you are in there for sure.

I have found that yoke and output bearing vibrations usually start early and get worse as speed increases, they don't usually appear in one narrow range, but will disappear at one certain "sweet spot" where rotation makes everything smooth out.
 

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I believe RWAL is rear wheel antilock and I don't have that. Just the valve that senses load at the rear axle.

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That’s LSPV - load sensing proportional valve. And I agree about checking the balance of the rear tires. You won’t feel that in the steering wheel, although you may get a bit of a vibration (or even shake) at the rear of the car.
 

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I don't know what RWAL or LSPV stand for. I blocked the brake pedal partway down when I removed the calipers so no air could enter the master. Then I only have to bleed the front as only small air pocket in the front lines. Works wonderful and Dave's work.

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What & Why? I have never heard of this practice. I have always used a large screwdriver placed between the pad and rotor to compress the piston just enough to remove the caliper and THEN used a C Clamp to compress it completely. I have never had to bleed the brakes after replacing the pads.
As far as the hard pedal, I had a sticking caliper that caused this condition in my case.
As far as the vibration, sound like you have a balance issue or bad tire since your vibration is not RPM related.
B95
 

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Discussion Starter #16
The reason for depressing the master cylinder is because I removed the calipers to rebuild them. Pressing the master partway and blocking it keeps the master from draining with open lines and keeps you from having to bleed the master. You are correct this is not necessary when the calipers are left connected.

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The reason for depressing the master cylinder is because I removed the calipers to rebuild them. Pressing the master partway and blocking it keeps the master from draining with open lines and keeps you from having to bleed the master. You are correct this is not necessary when the calipers are left connected.

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and i re-iterate, this WILL NOT prevent fluid from draining from the master cyl reservoir due to the one way valve under the seal cups, and can cause the front piston section in the master cylinder to jam. It will still drain albeit slowly. Don't believe me, check how a master cylinder works and how the non return washer performs its function, this is also why its bad practice (especially on Toyotas) to just push pads back in, it does cause damage in some cases.

bleed your brakes properly.

if a newer model full tandem with bypass drillings then the non return washers are not fitted. They are on these models however.
 

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Discussion Starter #18
You may be right, I will have to look in the manual... That said, my pedal effort did no change after doing the front brakes and rebuilding the calipers. There is non of the sponginess present when air is present. The system has a proper bleed and fronts and rears are being actuated properly. Issue is what feels to me to be high pedal effort for such a light car with power disk brakes.
This weekend I will replace rear slaves and hose if it arrives in time, but I don't expect that to change pedal effort much if any as they are functional now.
Where is the vacuum check valve located on the brake booster? I don't see one on the vacuum booster itself - is it in the hose?
Thanks,
Doug

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The check valve is in the hose nearest the booster; if you look close you'll see a bulge near the middle.
 
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