'97 Tahoe Reformation -Official Build Thread 8.1L/4L80E Swap

Performance modifications, tips & tricks

Moderators: flyingpolarbear, Dev, James B.

KennyB01
Posts: 161
Joined: Tue Jun 30, 2009 6:16 am
Location: sin city

Post by KennyB01 »

you have a combination that i have never heard of, so really you have a one of a kind and that is what we all try to achieve. nice job, you have bragging rights. :)

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

CrazyHoe wrote:How do you find the GMT800 MC vc the GMT400?
Not impressed so far. I might still have a bubble. Honestly, it grabbed better with the GMT400 MC. I planning to bleed again, just to be sure. Hoping that firms it up.
That sucks. You might need to press harder for the same braking power due to the bigger piston area of the GMT800 MC, but the brakes should feel firmer.

JR96CK
Posts: 1515
Joined: Fri Apr 03, 1998 8:12 pm
Location: Texas

Post by JR96CK »

CrazyHoe wrote:
CrazyHoe wrote:How do you find the GMT800 MC vc the GMT400?
Not impressed so far. I might still have a bubble. Honestly, it grabbed better with the GMT400 MC. I planning to bleed again, just to be sure. Hoping that firms it up.
That sucks. You might need to press harder for the same braking power due to the bigger piston area of the GMT800 MC, but the brakes should feel firmer.
Yep, something is awry... the brake pedal should get a LOT firmer and much higher up on the pedal.

Whipped383
Posts: 2104
Joined: Mon Mar 01, 2010 9:12 pm
Location: Salt Lake, 97K1500,ECSB, 383,Whipple,0411,Marine, 03K2500,CCSB,8.1&Allison, Whipple in progress

Post by Whipped383 »

Truck looks good man I bet your grinnin ear to ear or at least you will be till you hit the pumps lol the 8.1 is sure a beast but definatly a toilet. I think you need to look into the HP3 mods pauly was talkin about and let me know how you like them

jakenatour
Posts: 316
Joined: Wed Aug 15, 2012 10:48 am
Location: '97 Tahoe, 4DR 4WD Vortec L18, 4L80E

Post by jakenatour »

JR96CK wrote:
Yep, something is awry... the brake pedal should get a LOT firmer and much higher up on the pedal.
Don't know what it might be. I power bled the whole system very thoroughly including cycling the pedal a few times. I did get some air out of the rear circuit, which I thought was my problem. Did the other three wheels just to be sure. It didn't get any better. There is a lot of pedal travel and it is really tough to get them to lock up. It feels like it did before the brakes were bedded.

The rears are adjusted. My only idea is that the ABS unit is capturing some air again. I'm ready to go back to the new old unit. Not happy about it since the wiring will be a PITA to work around and I had to overtighten the POS Summit brake line adapter to get it not to leak. I'm wondering if I'll ever get that flare nut loose.

jrr344
Posts: 205
Joined: Tue Jul 27, 2010 7:44 am
Location: Tennessee

Post by jrr344 »

jakenatour wrote:
JR96CK wrote:
Yep, something is awry... the brake pedal should get a LOT firmer and much higher up on the pedal.
Don't know what it might be. I power bled the whole system very thoroughly including cycling the pedal a few times. I did get some air out of the rear circuit, which I thought was my problem. Did the other three wheels just to be sure. It didn't get any better. There is a lot of pedal travel and it is really tough to get them to lock up. It feels like it did before the brakes were bedded.

The rears are adjusted. My only idea is that the ABS unit is capturing some air again. I'm ready to go back to the new old unit. Not happy about it since the wiring will be a PITA to work around and I had to overtighten the POS Summit brake line adapter to get it not to leak. I'm wondering if I'll ever get that flare nut loose.


I have had the same problem with the oreilly's fittings both I have put in I have had to use vise grips to get them tight enough not to leak I would recommend to anyone doing this to take the extra time and put the right nut on and double flare the line again. When I put it all together and tightened it more than it should have needed tightened it leaked and sucked air into the system so I tightened it until my line wrench slipped on the nut and had to get vise grips to tighten it where it would not leak.

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

jrr344 wrote:
jakenatour wrote:
JR96CK wrote:
Yep, something is awry... the brake pedal should get a LOT firmer and much higher up on the pedal.
Don't know what it might be. I power bled the whole system very thoroughly including cycling the pedal a few times. I did get some air out of the rear circuit, which I thought was my problem. Did the other three wheels just to be sure. It didn't get any better. There is a lot of pedal travel and it is really tough to get them to lock up. It feels like it did before the brakes were bedded.

The rears are adjusted. My only idea is that the ABS unit is capturing some air again. I'm ready to go back to the new old unit. Not happy about it since the wiring will be a PITA to work around and I had to overtighten the POS Summit brake line adapter to get it not to leak. I'm wondering if I'll ever get that flare nut loose.


I have had the same problem with the oreilly's fittings both I have put in I have had to use vise grips to get them tight enough not to leak I would recommend to anyone doing this to take the extra time and put the right nut on and double flare the line again. When I put it all together and tightened it more than it should have needed tightened it leaked and sucked air into the system so I tightened it until my line wrench slipped on the nut and had to get vise grips to tighten it where it would not leak.
I knew it!!!

I argued with my parts guy till I was blue in the face last year when I bought mine. There's a mismatch between the taper sizes. Now I forget if it was between the fitting and the MC or between the line and the fitting.

IIRC, It's about seating a 1/4" female flair onto a 3/16" male. The shoulders bottoms out before the conical parts come in contact. If this is between the line and the fitting, I suggest not fully forming the second step of the flair (half way) and let the fitting finish the shape.

I have mine connected and the pedal is nice and firm.

I think when you reversed bled the MC, you might have trapped air in the MC. plus you might still have air in the ABS unit.

----
To remove the air from the MC, I suggest raising the rear of the truck so that the rear of the MC is clearly higher than the front and then squeezing the calipers with a few turns of a C clamp. that should expel any remaining air in the MC.
----

This is not from a text book bleeding procedure. This is from me spending hours analyzing the MC's passages and how they work.

If this doesn't improve your brake feel, then I'm pretty sure you still have air in the ABS unit.

With the engine off, I have about 1.5" of pedal travel before it's firm.

jakenatour
Posts: 316
Joined: Wed Aug 15, 2012 10:48 am
Location: '97 Tahoe, 4DR 4WD Vortec L18, 4L80E

Post by jakenatour »

CrazyHoe wrote:
With the engine off, I have about 1.5" of pedal travel before it's firm.
That's interesting. I've been playing with my brakes a lot and I realize it's definitely not right. I can get the pedal to firm up nicely with the engine off, but it takes two or three pumps from rest to get it to firm up. You can hear the swish for the first couple of strokes and then its quiet, firm and the travel reduces.

With vacuum assist, I'm pretty sure I have a pedal that's bottoming out. I can get the brakes to grab fairly decently, I just can't seem to get that last bit of grab to engage ABS or lock the wheels. My friend who helped me bleed became concerned that the pedal travel was seriously excessive since it seemed to go as low during stationary braking as with the bleed valve open. That's what makes me think it is bottoming out.

I didn't think that pumping the brakes was an indicator of an air in the lines problem. I always thought that it was indicative of a worn MC that is leaking by. That doesn't make sense in this case.

I will investigate how to get rid of any trapped air.

JR96CK
Posts: 1515
Joined: Fri Apr 03, 1998 8:12 pm
Location: Texas

Post by JR96CK »

jakenatour wrote:
CrazyHoe wrote:
With the engine off, I have about 1.5" of pedal travel before it's firm.
That's interesting. I've been playing with my brakes a lot and I realize it's definitely not right. I can get the pedal to firm up nicely with the engine off, but it takes two or three pumps from rest to get it to firm up. You can hear the swish for the first couple of strokes and then its quiet, firm and the travel reduces.

With vacuum assist, I'm pretty sure I have a pedal that's bottoming out. I can get the brakes to grab fairly decently, I just can't seem to get that last bit of grab to engage ABS or lock the wheels. My friend who helped me bleed became concerned that the pedal travel was seriously excessive since it seemed to go as low during stationary braking as with the bleed valve open. That's what makes me think it is bottoming out.

I didn't think that pumping the brakes was an indicator of an air in the lines problem. I always thought that it was indicative of a worn MC that is leaking by. That doesn't make sense in this case.

I will investigate how to get rid of any trapped air.
If you can rule out a defective master cylinder (don't know what brand you went with, hopefully new AC-Delco), then it really might be worth the time and money to find a shop with a scanner that can run the bleed procedure. If I was local to you, I would gladly swing by with my Snap-On scanner and help you out. But, just about any shop should have an old Snap-On "Brick" scanner with the black cartridges which can do the ABS bleed, or some newer scanner like a OTC Genesys (sp?), Snap-On Modus, Solus, etc. I'm sure any dealer can do it with a Tech-II, but they would charge more than an indepedent shop and would probably make an issue about the "wrong" mster cylinder being on there as per their usual mindless corporate B.S.

I can personally assure you that when you get the underlying issue resolved, you will notice a significant improvemnet with this MC.

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

JR96CK wrote:I'm sure any dealer can do it with a Tech-II, but they would charge more than an indepedent shop and would probably make an issue about the "wrong" mster cylinder being on there as per their usual mindless corporate B.S.
I asked a 50+ year old parts guy if GM had an improved "low drag caliper".

Answer:
"What's a low drag caliper?"

jakenatour
Posts: 316
Joined: Wed Aug 15, 2012 10:48 am
Location: '97 Tahoe, 4DR 4WD Vortec L18, 4L80E

Post by jakenatour »

JR96CK wrote: If you can rule out a defective master cylinder (don't know what brand you went with, hopefully new AC-Delco),
Yes, new AC-Delco.
JR96CK wrote: I can personally assure you that when you get the underlying issue resolved, you will notice a significant improvemnet with this MC.
I sure hope so - I definitely don't want to R&R that MC again...

I will try the braking in a gravel parking lot technique again - that seemed to work pretty well the first time. If that doesn't do it, I will find someone with the tool.

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

Why air stays trapped in the system if it won't exit by itself.
The intake and return ports are tiny orifices and it's possible that the air won't escape because of surface tension.
-----------------------------


The orifices are at the top rear of each cylinders and as you can see, it's impossible to bleed the air with the front up.
Image
-----------------------------



You can't pump the air out cause as you can see, pressing on the piston closes the escape hole
Image
----------------------------


This is what I suggested to do if there is actually air trapped in the MC
Image


Tapping on the end of the MC with a piece of wood could vibrate the mc enough to burp the bubles.
But I suggested compressing the calipers.

jakenatour
Posts: 316
Joined: Wed Aug 15, 2012 10:48 am
Location: '97 Tahoe, 4DR 4WD Vortec L18, 4L80E

Post by jakenatour »

Drove over 200 miles Monday to get some deeply discounted tires and wheels. Gotta love Craigslist. I'll show pics after they're mounted.

She still purrs and shows no signs of leaks, rattles, or whines. Temp and oil pressure held steady as a rock. The only time the temp moved from 190 deg was when I was in stop and go traffic in downtown SF. Temp crept up to 205 or so.

The brakes were serviceable but, for reasons previously mentioned, I kept some extra distance from the cars in front of me.
Last edited by jakenatour on Sun May 08, 2016 6:40 am, edited 1 time in total.

jakenatour
Posts: 316
Joined: Wed Aug 15, 2012 10:48 am
Location: '97 Tahoe, 4DR 4WD Vortec L18, 4L80E

Post by jakenatour »

Here's the wheels installed.

These are Toyota wheels, unpolished, with garbage BFG All Terrains installed 315/75/R16 (~35" diameter, 12.5" wide). Craigslist $140

Not crazy about the look of the wheels. I have the center caps. I'm toying with painting them satin black with a rattle can.

Picked up some brand new BFG All Terrains to mount to these wheels. Same size. $850 which is a steal.

What's your vote on the wheel color: Black or Natural?

Image
Last edited by jakenatour on Sun May 08, 2016 6:41 am, edited 1 time in total.

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

Ever thought of Plasti dip rattle can? Can be peeled off if you change your mind.

http://www.plastidip.com/home_solutions/Plasti_Dip
Image
ImageImage

z71gmc06
Posts: 1013
Joined: Tue May 08, 2007 12:45 pm
Location: Michigan

Post by z71gmc06 »

I vote for black wheels, but keep your center caps chrome.

Tahoe is looking good.

jakenatour
Posts: 316
Joined: Wed Aug 15, 2012 10:48 am
Location: '97 Tahoe, 4DR 4WD Vortec L18, 4L80E

Post by jakenatour »

Two cans of PlastiDip black just purchased. I like the minimal prep, undo option. I'll get that shot next week.

Thanks.

CrazyHoe
Posts: 6228
Joined: Tue Feb 19, 2008 8:30 am
Location: Mtl; '98 2dr4x4 Tahoe, L31,Hookers Long T, 0411,EFIlive, 4L80-E,dual 3",marine int+inj

Post by CrazyHoe »

Lots of vids on how to dip cars.

GunMetal Gray Plasti Dip - Wheels and Rims
https://www.youtube.com/watch?v=DPNNAC7lOro

Plasti Dip Emblems and Front Grille
https://www.youtube.com/watch?v=u8Gfd46AxLw

PlastiDip M3 Matte White
https://www.youtube.com/watch?v=jayyTUy3GTw

R8
https://www.youtube.com/watch?v=h_Ta1KTrzqg

Peeling
https://www.youtube.com/watch?v=0r7xvBSqhOE

Speeder
Posts: 10763
Joined: Fri Apr 30, 1999 9:12 pm
Location: 2021 Dodge Durango R/T 2WD, 2008 Colorado work beater, 2003 Dodge Dakota pro-touring project

Post by Speeder »

That Plastidip is pretty popular over on the Lincoln board I post to. They paint their entire cars with the stuff.

Going to be fixing the paint on mine this week and getting it ready to sell. I'm sick of that car. Will probably get a used Camry or something to replace it for now, just some beater to get me around for a bit.

Whipped383
Posts: 2104
Joined: Mon Mar 01, 2010 9:12 pm
Location: Salt Lake, 97K1500,ECSB, 383,Whipple,0411,Marine, 03K2500,CCSB,8.1&Allison, Whipple in progress

Post by Whipped383 »

Oh man I was gonna vote natural finish just polish them up a bit. I dont understand why people pay big bucks for black rims when they can just take thier hub caps off and have it look like shit lmao.

Post Reply