My new 86 GN. Great car but needs some love.

SteveZ82

Active Member
Hey all,

I've been posting to the site here and there with some questions I've been having with my newly purchased 86GN. I purchased the car about 5 months ago and have been doing some work to it to get it perfectly roadworthy. Not that it isn't drive-able but it's one of those cars that runs great but the PO skipped some important maintenance on it in the last 33 years. The car is very clean, has a great paint job that was done some time in the early 2000s and a very immaculate engine bay and interior that looks to be original with some quality bolt ons. Bolt ons include an applied tech cold air kit, TT chip, new garrett looking turbo with a precision turbo outlet bell, and an aftermarket stereo that I completely despise. So, when I got the car, the PO told me that the powermaster was on the way out, noticed I have a crack in the DS exhaust manifold (common I know), no AC, the tires were dry rot, new springs and Bilstein shocks.

So, after a very extensive look at the car on the rack, I replaced the tires, the powermaster with an Earl Brown vacuum kit (long story there), new body bushings (these were bad), recharged the AC with R12, and upper control arm bushings on the PS A arm. The car really feels great now with the new body bushings and fresh control arm but I have a few issues with some other things.

After I replaced the master with a vacuum type, I was really getting on the car one night and completely melted my front center caps. When I pulled into the garage there was smoke coming from both front wheels and you couldn't even get near the front rims without burning your fingers. Now on to the meat.

1) I had the car out a few times after that and even on a simple around town ride, the front rims get super hot after about 5 miles of light traffic stop and go. Both rims in the front are super hot but the back ones feel fine so I'm wondering if I have a bad proportioning valve or is this just normal? You cant even touch the lugs without getting burned.

2) Noticed today that from a stop, I get a little vibration on acceleration. I never noticed it before the work done so curious if I may have sticking caliper(s) or something else with the drivetrain.

3) When I engage into R or D I get a loud clang. I have replaced the oil in the rear end with some 75w-90 lucas oil and the proper posi additive from Kirbans. When I drive the car around I feel and hear nothing out of the ordinary so curious what this could be. The u-joints are original by the way and the rear end pinion and ring gear looked fine when I replaced the oil.

Any advice would be great and I appreciate all in this community.
 

grass doctor

Dream Catcher
you might need new calipers or to bleed the brakes again might still have air in there , wrapped rotors will cause vibration if lugs put on with gun to tight can cause wrapped rotors 80 ftlbs is recommended I use torque sticks , unsure on rear end but loud clang not good might be something with tranny if nothing sounds or feels wrong when driving
 

John Larkin

Sublime Master of Turbology
You could easily have an internally collapsed brake hose and considering what you said about the car needing maintenance, that is where I would check first. They will only allow fluid to pass easily one way when they go bad. Parts house replacements are fine as long as they are good quality. Secondarily, consider the master cylinder as a culprit also. The OEM calipers work with a Quick Take Up master cylinder. In brief, this means the master cylinder lets the calipers back off slightly when rolling which enhances fuel economy and reduces friction, then when the brake is applied it closes that gap quickly and normal braking happens. If you use something from a normal G-body from mid 80s (I bought a reman 1985 Grand Prix master cylinder) it will work. The test is to install it, bleed, take the reservior cover off and press the brake pedal. You should see a spurt of fluid about 1" above the fluid level (put some towels all around so you don't make a mess). That is the Quick Take Up function. No spurt = not working.
 

SteveZ82

Active Member
You could easily have an internally collapsed brake hose and considering what you said about the car needing maintenance, that is where I would check first. They will only allow fluid to pass easily one way when they go bad. Parts house replacements are fine as long as they are good quality. Secondarily, consider the master cylinder as a culprit also. The OEM calipers work with a Quick Take Up master cylinder. In brief, this means the master cylinder lets the calipers back off slightly when rolling which enhances fuel economy and reduces friction, then when the brake is applied it closes that gap quickly and normal braking happens. If you use something from a normal G-body from mid 80s (I bought a reman 1985 Grand Prix master cylinder) it will work. The test is to install it, bleed, take the reservior cover off and press the brake pedal. You should see a spurt of fluid about 1" above the fluid level (put some towels all around so you don't make a mess). That is the Quick Take Up function. No spurt = not working.

I’ll try this. I have some SS lines to put on because I suspect those front hoses are past their life. I posted this because I found it odd that both front wheels are super hot after a short ride.


Sent from my iPhone using Tapatalk
 

John Larkin

Sublime Master of Turbology
As for the clang into gear, Spicer sealed ujoints are the best. 5-795X Dana Spicer 3R Series Non Greasable U Joint are what I used. You have to heat the stock ones with a propane torch as they have a plastic seal inside. When you heat it, it will come out like a worm, it's crazy looking. But you'll never get them pressed out without heating first or damage could occur.
 

tquick87

Member
I agree about changing the front brake lines to stainless, then bleeding really well. Also make sure it has the brass proportioning valve instead of the cast.
 

SteveZ82

Active Member
I agree about changing the front brake lines to stainless, then bleeding really well. Also make sure it has the brass proportioning valve instead of the cast.
I still have the cast one. I'll order a brass one from Kirbans. Is that hard to bleed?
 

tquick87

Member
Its harder to put on than bleeding lol. Just follow the normal bleeding procedure:
  1. RIGHT REAR
  2. LEFT REAR
  3. RIGHT FRONT
  4. LEFT FRONT


The brake bleed procedure is at the bottom of this article. I use a vacuum bleeder so I can do it myself.

Hope this helps. Your car will feel much better!
 

SteveZ82

Active Member
Its harder to put on than bleeding lol. Just follow the normal bleeding procedure:
  1. RIGHT REAR
  2. LEFT REAR
  3. RIGHT FRONT
  4. LEFT FRONT

The brake bleed procedure is at the bottom of this article. I use a vacuum bleeder so I can do it myself.

Hope this helps. Your car will feel much better!
Thanks! Yeah, I've bled a ton of brakes so I need to go ahead and take my time with this one. I admit, I kinda rushed it because I wanted to drive the car. You read all these different opinions about what could be happening and my anxiety then goes to 11. Earl Brown seems to be a guru on these cars so I trust the parts he gave me are good and I just didn't take my time. I also hear that the brakes on these cars do run hot. That true?

I too have a vacuum bleeder and have done the coke bottle trick with success.
 

SteveZ82

Active Member
No clue if they run hot compared to other cars.

Let us know how things go after the prop valve change.
I lifted the car up again and spun the tires after pumping the brakes a bit. I do notice a bit of dragging on my DS compared to my PS. I'll get in there after I get the parts and do a proper bleed. Thanks for the help.
 

dank GN

BlackArts Automotive (661)993-8277
Okay before u go and buy anymore parts u should get yourself a scanmaster so you will be able to have some information on what the engine is actually doing . Or hopefully you already have one . But on the brake issues you can upgrade the rear brakes to a bigger wheel cylinder from a manual S-10 I forget what year but it’s a cheap rear brake upgrade just search it on here it will pop up . Keep us posted
 

SteveZ82

Active Member
Okay before u go and buy anymore parts u should get yourself a scanmaster so you will be able to have some information on what the engine is actually doing . Or hopefully you already have one . But on the brake issues you can upgrade the rear brakes to a bigger wheel cylinder from a manual S-10 I forget what year but it’s a cheap rear brake upgrade just search it on here it will pop up . Keep us posted
I don't have a scanmaster but do have an older ADAL scanner that does data stream. Motor is solid hovering around 128 BLMs give or take =+- 5 BLMs, TPS, O2, MAT look normal as well. Will do. I actually have the upgraded cylinders and it will be part of the maintenance.
 
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