Hi All, New to CAC, and I have a few questions about my 1986 z51 coupe.

[docderek05]

Hello to Everyone,
Glad to be on this forum..

I have two C4's a 1994 DRM Coupe and a 1986 Black Coupe.

My questions concern the 1986.

a. Are there Anti Rattle clips, available for this year's Brake Caliper to isolate it from the Rotor?

b. the Previous owner put in an aftermarket performance chip, which totally
screwed up the fan settings, and the shift points of this Tranny , its automatic, does anyone
know of a source for a factory spec chip, to replace into the main computer. or do I need to
just hunt down a new spec. computer?.

c. The drivetrain is fairly robust, other than the harsh shiftpoints, my corvette mech. has the tranny
shift levers all to spec. and the transmission, when you are not standing on it...shifts as it should.
1,2 3,4 But because Prior owner changed out the factory chip, the "upshift" light is annoying as hell,
as it is not coming on when it should, and I have to whack the throttle for it go out..

d. I know a z51 is a hard ride around town, especially in New England, and the mine fields we call roads!,
but I have 107,000 on the clock of the 86, is it true that poly bushings squeek? I want to change out
my dog bone bushings, my sway end links..but is poly a good idea, for a car that will not be tracked?
I do not want to add to my current symphony of sounds, from the suspension, on side streets.

Sorry for the long winded intro, but I appreciate any imput and advice,
and I hope I have some knowledge to share with some of you at a future point,

I have been a vette owner since I was 17, I am 54 now, so I have my share of
experience with C3, and presently some C4 experience. Hoping to someday have C7 experience!!

Best to you All, Derek

 

[toptechx6]

Hello to Everyone,
Glad to be on this forum..

I have two C4's a 1994 DRM Coupe and a 1986 Black Coupe.

My questions concern the 1986.

a. Are there Anti Rattle clips, available for this year's Brake Caliper to isolate it from the Rotor?

b. the Previous owner put in an aftermarket performance chip, which totally
screwed up the fan settings, and the shift points of this Tranny , its automatic, does anyone
know of a source for a factory spec chip, to replace into the main computer. or do I need to
just hunt down a new spec. computer?.

c. The drivetrain is fairly robust, other than the harsh shiftpoints, my corvette mech. has the tranny
shift levers all to spec. and the transmission, when you are not standing on it...shifts as it should.
1,2 3,4 But because Prior owner changed out the factory chip, the "upshift" light is annoying as hell,
as it is not coming on when it should, and I have to whack the throttle for it go out..

d. I know a z51 is a hard ride around town, especially in New England, and the mine fields we call roads!,
but I have 107,000 on the clock of the 86, is it true that poly bushings squeek? I want to change out
my dog bone bushings, my sway end links..but is poly a good idea, for a car that will not be tracked?
I do not want to add to my current symphony of sounds, from the suspension, on side streets.

Sorry for the long winded intro, but I appreciate any imput and advice,
and I hope I have some knowledge to share with some of you at a future point,

I have been a vette owner since I was 17, I am 54 now, so I have my share of
experience with C3, and presently some C4 experience. Hoping to someday have C7 experience!!

Best to you All, Derek

The aftermarket chip may be affecting the fan operation and upshift light (which should only be on a manual car) but it has nothing to do with transmission shift points or harshness. The ECM only controls torque converter lock up. Transmission shifts on your 86 are controlled by a hydraulic governor with pressure modified by a cable controlled throttle valve based on throttle opening. Sounds like the transmission has a shift kit installed and will likely require valve body replacement to restore stock shift characteristics.

 

[Hib Halverson]

The aftermarket chip may be affecting the fan operation and upshift light (which should only be on a manual car) but it has nothing to do with transmission shift points or harshness. The ECM only controls torque converter lock up. Transmission shifts on your 86 are controlled by a hydraulic governor with pressure modified by a cable controlled throttle valve based on throttle opening. Sounds like the transmission has a shift kit installed and will likely require valve body replacement to restore stock shift characteristics.

"toptechx6" is right. No trans with electronic controls until the early 90s. If you've got a problem with shift points or shift firmness, either the trans is messed up somewhere or someone installed an aftermarket "shift kit".

Before you go looking for a stock cal...which you'll have a hard time finding, I surmise...check what fan-on temps. You may be better off with lower fan-ons.

As for poly bushings for street use on highways in New England...don't do it. You'll regret the harshness and the noise.

Lastly, welcome to the CAC!

 

[docderek05]

"toptechx6" is right. No trans with electronic controls until the early 90s. If you've got a problem with shift points or shift firmness, either the trans is messed up somewhere or someone installed an aftermarket "shift kit".

Before you go looking for a stock cal...which you'll have a hard time finding, I surmise...check what fan-on temps. You may be better off with lower fan-ons.

As for poly bushings for street use on highways in New England...don't do it. You'll regret the harshness and the noise.

Lastly, welcome to the CAC!

Gentlemen,

Thank you both for the rapid response. I would now then suspect the 86 has been re-fit with a new dash cluster, for a manual car. everything below the car seems to indeed have the same patina of wear, it does not appear to have been retrofitted with an automatic, vs. a standard, so i have to suspect its period correct, and not refit, mechanically. hence the upshift light, however the upshift light does function in relation to RPM, so I am perplexed as to what to do about it. is there a way to defeat it, without pulling the dash? the plot thickens...!! this is reminding me of that tv commercial where the announcer said, "People do funny things to cars," and you see the Dalmation driving..!!!
I appreciate any insight. Thank you to Hib and toptechx6

 

[docderek05]

The aftermarket chip may be affecting the fan operation and upshift light (which should only be on a manual car) but it has nothing to do with transmission shift points or harshness. The ECM only controls torque converter lock up. Transmission shifts on your 86 are controlled by a hydraulic governor with pressure modified by a cable controlled throttle valve based on throttle opening. Sounds like the transmission has a shift kit installed and will likely require valve body replacement to restore stock shift characteristics.

topTechx6...I would never have thought this myself, I was thinking it was another dash out of a manual car..
I found this text below. I learned something new..I completely agree with what you said above. so i was researching how to defeat the damn thing
and came across this. ..

Fuel capacity on automatic cars shriveled by two gallons to 18. LCD instruments were re-angled to aid daytime legibility (which remained difficult all the same), and the cluster now contained an upshift indicator light that was there to help drivers achieve maximum mileage by signaling when to shift gears -- it was there to help keep the car's EPA mileage figures above the gas-guzzler level. (Oddly, the indicator light also came with the automatic transmission.) Standard tires were changed to P245/VR5016s; the Z51 package continued with P255s.

 

[djsroknrol]

the cluster now contained an upshift indicator light that was there to help drivers achieve maximum mileage by signaling when to shift gears

My dash has one and I have an '84...does that mean that it was available earlier than '86 or has my dash been changed?

 

[bmw_bill]

C4 Tranny Question - and possible answers

WOW....I finally have some practical input to a legit question!

I have an 87 C4 with 700R4 Automatic transmission. The shift light is in it as is with my father-in-law's 85 Z51 with auto. They both function similarly....especially when you leave the car in a low gear (manually shifting) over a prolong period of time. Simply, it reminds you to put the car into overdrive when you get up to a higher speed. So...it's NOT a manual only option/function.

Next....everyone is correct...the tranny is NOT computer controlled. However, your description of the tranny shifting behavior sounds like a TV adjustment issue. No...not television folks....the TV cable!

Here's a helpful article to explain the function and adjustment of the TPI TV cable: Adjusting TV Cables - Tech Article - Chevy High Performance Magazine

I adjusted this on my car in order for the transmission to feel.....more sporting like....and it does in fact make a material difference.

So....what do you think guys? Did I help here?

Cheers

BillR

 

[WhalePirot]

Never seen an upshift light, but I recall reading of the changed angle of the digi-dash, post '84.

Thanks for the link BMW-bill; useful for my C-4 riding 1955 F100 w/700R4.

Roads here have been better that 'up north, back east', but with no rubber in the suspension, my Z51 communicates every pebble! I like the more precise handling, but I suspect the doc would agree with Hib. The poly bushing can squeak, tho I lube mine at each oil change, which also improves the suspension response.

Welcome to the forum, doc. Enjoy the car, despite the short-term travails!

 

[docderek05]

Thanks Guys...

Does anyone have some insight into the Anti-rattle clips, I have seen them, made of flat spring steel for the front calipers,
but I cannot find a source..anyone have these, and where I can get em, mine rattle so much that it makes me reflect on
my old '69...Best, Doc

 

[Hib Halverson]

I have to laugh at myself....I read the OP so fast I missed the idea that there's a shift light on the I/P of a car with an automatic.

It's possible the cluster was changed. Or heck, maybe the trans was converted from manual to automatic and whomever did the calibration left the shift light enabled...if that's even possible.

To be honest, I don't know enough about all the possibilities to answer the question accurately.

I wonder...
Is the shift light controlled from the calibration or the cluster? If it's the calibration...done right, why would an automatic cal have the shift light enabled?

In any event, the easy way to stop it is take out the bulb.

As for antirattle clips, the Factory Service Manual shows no antirattle devices on 86 brake calipers.

 

[DarkRed89Flyer]

I have to laugh at myself....I read the OP so fast I missed the idea that there's a shift light on the I/P of a car with an automatic.

It's possible the cluster was changed. Or heck, maybe the trans was converted from manual to automatic and whomever did the calibration left the shift light enabled...if that's even possible.

To be honest, I don't know enough about all the possibilities to answer the question accurately.

I wonder...
Is the shift light controlled from the calibration or the cluster? If it's the calibration...done right, why would an automatic cal have the shift light enabled?

In any event, the easy way to stop it is take out the bulb.

As for antirattle clips, the Factory Service Manual shows no antirattle devices on 86 brake calipers.

Hi, docderek05!

Welcome to the CAC!!

First, I must point out that my '89 with an automatic (original option) also has the Upshift Light in the main cluster just above the tach's bar graph. Although, in the 2 years I've had the car, I've never seen it illuminate. You can make out the faint outline of it at night when the headlights are on. So, to Hib's comment above, it isn't simply a matter of taking out the bulb since there isn't one. It's part of the LCD. Your best option might be to just swap the whole computer, if you can find a reman or used one that came out of a car similarly equipped with the automatic. The only other option I can think of, would be to order a new aftermarket CAL chip that is the correct one for your car.

As for the early on fan temps, it might be better to leave well enough alone. Here in Arizona, I think the fans don't come on soon enough, and I often see the 230's in mid-summer while driving on the freeway during rush hour, when my speeds are usually limited to 40 mph or less. It concerns me so much that I wired two switches into the system to turn the fans (mine has the B4P Booster Fan option) on sooner than the computer does.

Second, I would have to agree that if the tranny is shifting harder than you expect, it probably has a "shift kit" installed. Or, the TV cable needs adjustment. Even on my '89, I have one of those cables, so I know yours isn't computer-controlled either. I can tell you, though, when I'm tromping on the gas in mine, it tries to shove me back under the glass hatchback, when it shifts from 1st to 2nd. If I'm just tooling around town, however, I can barely feel it upshift through any gear.

 

[docderek05]

Hi, docderek05!

Welcome to the CAC!!

First, I must point out that my '89 with an automatic (original option) also has the Upshift Light in the main cluster just above the tach's bar graph. Although, in the 2 years I've had the car, I've never seen it illuminate. You can make out the faint outline of it at night when the headlights are on. So, to Hib's comment above, it isn't simply a matter of taking out the bulb since there isn't one. It's part of the LCD. Your best option might be to just swap the whole computer, if you can find a reman or used one that came out of a car similarly equipped with the automatic. The only other option I can think of, would be to order a new aftermarket CAL chip that is the correct one for your car.

As for the early on fan temps, it might be better to leave well enough alone. Here in Arizona, I think the fans don't come on soon enough, and I often see the 230's in mid-summer while driving on the freeway during rush hour, when my speeds are usually limited to 40 mph or less. It concerns me so much that I wired two switches into the system to turn the fans (mine has the B4P Booster Fan option) on sooner than the computer does.

Second, I would have to agree that if the tranny is shifting harder than you expect, it probably has a "shift kit" installed. Or, the TV cable needs adjustment. Even on my '89, I have one of those cables, so I know yours isn't computer-controlled either. I can tell you, though, when I'm tromping on the gas in mine, it tries to shove me back under the glass hatchback, when it shifts from 1st to 2nd. If I'm just tooling around town, however, I can barely feel it upshift through any gear.

Dark Red..thank you !...I am thinking, at this point, live with it. just wap the throttle when it comes on and ignore it..its almost a 28 year old car..but I have it polished like a diamond and it looks brand new, so the electrical gremlins bother the heck out of me..the interior, all the LED functions perfectly, including the ridiculous 85 mph top speedo..previous owner was as fanatical as I am...so the car is really nice for it's year, and most C4s I see in my area are real basket cases, cold weather, uneven, salted roads, not corvette heaven, for sure!

Hib, you are a wealth of Knowledge, and I am glad that you are here, It was one of your C4 articles, "Hib Halverson remembers the C4 Corvette" that got me interested in the C4 gen cars to begin with, following my owning of the C3's in my past. I appreciate your help very much, thank you, sir.

All, I am glad to be here, thank you for any advice now and in the future,

Best to Everyone, Derek

 

[WhalePirot]

the ridiculous 85 mph top speedo.

Yes, but the digital goes a LOT higher!

 

[Hib Halverson]

I guess I'm a bit rusty on early C4 electrics. There are bulbs for the LCD display...there'd have to be as it's a liquid crystal display not a light emiting diode display. They're halogen bulbs, four of them, which can be replaced if necessary.

That said, unlike the MIL, the SRC service light and so forth there is no separate bulb for the shift light, as "DarkRed89Flyer" suggests, the shift light is an LCD which uses those halogens for a backlight so, obviously, my idea of taking out the bulb is lame. Sorry 'bout that.

Hib, you are a wealth of Knowledge, and I am glad that you are here, It was one of your C4 articles, "Hib Halverson remembers the C4 Corvette" that got me interested in the C4 gen cars to begin with, following my owning of the C3's in my past. I appreciate your help very much, thank you, sir.

You're welcome Derek. Glad to be of service.

 

[roger longman]

My '88, stock, auto, has the upshift arrow, which comes on when it feels you may like to shift up, for economy reasons. It has worked consistently over the 12 years I've had the car.........Roger.