Some Differences between 95's and 90'/91's
 

Some differences in the 95' compared to the 90'/91' include:

1. EGR installed from Plenum to passenger side exhaust (SW has that connection on exhaust).
2. Drivers Side Exhaust connection to the Headers.
3. Only one Throttle Cable.
4. Security....Key Fob in Pocket will automatically Lock Doors as you move away from ZR-1.
5. Security....Key Fob in Pocket will automatically Open Doors as you approach ZR-1.
6. Radiator Plastic Drain Valve (still have not figured out how it functions).
7. Seat Control Selector (Drivers or Passenger Seat) on passenger side of console and Seat Control on Drivers Side of Console.
8. Jack is Stored in bottom of Storage behind Passenger Seat.
9. No Storage Area behind Drivers Seat.
10. No Glove Box.
11. Climate Control Trim Redesigned.
12. Gauges have changes in Appearance.
13. Jack Handle stored behind Drivers Seat.
14. Blue Label Transmission (albeit I have a Blue Label Transmission installed in my 91').
15. Seats are Re-Designed.
16. ALDL Plug is different.
17. Valley Drain under Starter is much larger on 95' and the tube between Bell Housing and oil pan is eliminated.
18. Injector Housings are different having the primary and secondary injector ports the same size (the same "O" ring).
19. The Primary and Secondary Injectors all take the same "O" ring but have a different colored band (white and blue).
20. On the 95' there exists a vacuum line and electrical on a separate module connected in front of the DIS along with the three electrical connectors connected to the Front of the DIS.
21. There is a filter on the Vacuum Solenoid of the 95' (Part #: 10159525).
22. Doors are redesigned and have small storage just below door release.
23. No Passenger Side Hatch Release at rear of Passenger Door.
24. The 95' Comes from GM with R134 AC System.
25. Improvements in NVH.
26. Door Panels Design Changes.
27. Crash Through Shifter.
28. Door Storage Pods.
29. No Hatch Release on Rear of Passenger Door.
30. FX3 Shocks Ride Selection Top Cam changed.
31. Windshield Radar Opening.
32. Wiper Blades.
33. Master Cylinder.
34. Selectable Data on SPEEDO LED.
35. Hood Emblems.
36. Top Wrench.
37. ABS.
38. Door Jam Locker (Silver alignment pin).
39. Fuse Blocks are Relocated in front and behind the battery.

1995 Plenum Restored
http://i287.photobucket.com/albums/l...29b460408c.jpg
http://i287.photobucket.com/albums/l...26e42aba54.jpg

1995 LT5 SPECIFIC TOP END REBUILD TRICKS
A 1995 Top End was rebuilt and best tricks linked here
Post 230 - Plenum, Alternator, Secondary Vacuum System, Coils, Starter Removed
Post 231 - Clean Up of Valley and Removal Of Crankcase Cover (gasket replaced)
Post 232 - Installation of Rebuilt Starter
Post 233 - Installation of Coils and New Spark Plug Wires
Post 234 - Installation of New Secondary Vacuum System hoses
Post 235 - Installation of Reconditioned Injectors with New "O" Rings
Post 236 - Installation/Relocation of Plug Wires and New Spark Plugs
Post 237 - Blocking TB Coolant
Post 238 - Reconditioning and Installation of Plenum with SS Allen Head Bolts
Post 239 - Addition of Billet Aluminum Power Steering, Water Pump, Belt Tensioner Pulleys
Post 240 - Reconditioned 1995 Engine with New Fluids all around including Differential Drain Installed

http://i287.photobucket.com/albums/l...85211032b4.jpg
http://i287.photobucket.com/albums/l...e70d7df1cb.jpg
http://i287.photobucket.com/albums/l...2dfa3588b7.jpg

Last UPDATE of post 1 Feb, 2016

Re: Some Differences between 95's and 90'/91's
 

#6 - GM 3056858 and best I recall it's never gone through any production design changes. A change in design would have changed the part #.

GOOGLE - Amazon have great images.

That plenum is "restored" - I'd say not but ......

Re: Some Differences between 95's and 90'/91's
 

There are also a lot of smaller, less noticeable improvements in NVH that improve the ride quality. Pieces of foam and/or Velcro like-material in a number of places. --Bob

Re: Some Differences between 95's and 90'/91's
 

Door panels are a huge difference.

The earlier panels are more secure / durable and better made.

The later ones are flimsy and not as sturdy... (I'm being kind here!)

:cheers:

David

Re: Some Differences between 95's and 90'/91's
 

Well.......20 out of 21 observations is not bad :D

"On the "Restored".........I have "Restored" 6 Plenums. One of those is Powder Coated. All of those have the same Unconventional Color Combination. Three of those had the original Powder Coating chips and flaking. In the Restoration I did NOT remove the original Powder Coat but DID remove the flaking original powder coat and did dress up the chips and flaking areas by sanding.

Five of those are Painted with Rustoleum High Heat which after considerable use none of those has changed color or the paint deteriorating in any way. An advantage to my methods is that the Painting is very easy to touch up in case of stains or damage after the fact. All of the Plenums have the Billet Aluminum TB Coolant Cover Installed (LT5).

And I might add.....only one of those has the TB Coolant Blocked and associated rubber hoses removed from the Plenum. The other five Plenums are associated with TB being Blocked at the Injector Housing with New Hoses associated with the original TB Coolant installed WITHOUT Hose Clamps just for looks.

Keep the Differences between model year observations coming....very informative :handshak:

Re: Some Differences between 95's and 90'/91's
 

#17, you should also have a larger drain tube in the bellhousing. 94s do

http://i540.photobucket.com/albums/g...ps1827de7b.jpg

Re: Some Differences between 95's and 90'/91's
 

I did not see any tube on 95'.......maybe tube is a press fit and got dislodged. I think there is a drain tube into the Bell Housing and then through the lower plate draining between that plate and Oil Pan. But.....I am not sure...will look in a minute.

Re: Some Differences between 95's and 90'/91's
 

Crash through shifter was on the 95. It is the only feature on the 95 I wish my 94 had. Though there are others.

Re: Some Differences between 95's and 90'/91's
 

The drain tube actually runs between the back of the block/oil pan and in front of the flywheel.

Re: Some Differences between 95's and 90'/91's
 

Go with a Hurst shifter or BB moded stocker

Re: Some Differences between 95's and 90'/91's
 

Valley Drain Port looks larger on 95' and goes from Valley into Bell Housing in front of Flywheel and then out with a large port in the Bell Housing Lower Cover plate (shown in photo looking upward in front of Bell Housing Lower Cover Plate and behind Rear of Oil Pan). No tube extends down as the Drain Port appears too large for a tube.

I actually applied engine degreaser and pressure washed the valley and the Larger Drain Port functions very well. I think if the Valley Drain Port on the 95' is not clogged with leaves that one could actually pressure wash the engine with no issues. I will add a photo of the Valley in a moment.

Valley with New Crankcase Cover Gasket installed
http://i287.photobucket.com/albums/l...17f93c2e34.jpg

Re: Some Differences between 95's and 90'/91's
 

You forgot the door storage pods :) 94-96

Re: Some Differences between 95's and 90'/91's
 

Is the hatch release backside of the passenger door still there? No Tire changing light either, Down in one window was on the 94 and up as well

Re: Some Differences between 95's and 90'/91's
 

No Hatch release on passenger door but does have Hatch release on Key Fob.

Re: Some Differences between 95's and 90'/91's
 

I believe 94s and 95s have softer springs but firmer shocks. 94s and 95s are raised a bit more than early cars to keep softer springs from causing nose scrape. I thinks this is achieved by extra rubber pads on the underside, outer edges of the front spring.

Re: Some Differences between 95's and 90'/91's
 

I dont recall an EGR on the 90. I'll look again....

Re: Some Differences between 95's and 90'/91's
 

No EGR until 93 (I think...). 94 and 95s have EGR.

Re: Some Differences between 95's and 90'/91's
 

Windshield

Re: Some Differences between 95's and 90'/91's
 

Windshield wiper to blade trunnion (different blades required)
Shocks
Shock gears
ASR & associated "stuff"
Master Cylinder
ABS (95 LT1 was upgraded & some say LT5 was too--can't remember)
Rear door jam "locker"--silver alignment pin
Rear storage compartments
Top wrench
No top bumpers (on inside frame) on 95s
Hood emblems & associated alignment holes
Selectable data on speedo LED

Re: Some Differences between 95's and 90'/91's
 

As Phil noted, go with a Hurst and eliminate the lift ring. I did that on my '93 and there is plenty of spring loading to keep you from putting it in reverse instead of fifth or sixth. Never had a problem and loved not having the lift ring. --Bob

Re: Some Differences between 95's and 90'/91's
 

Great topic. My only question, are the 94-95 seats more comfortable than 90-93? 94-95 seats appear bigger and wider, but are they softer?

Re: Some Differences between 95's and 90'/91's
 

I think that is totally dependent on your size.... I'm 5-10 170lbs and love the 90-93 seats, fit me just right.

Re: Some Differences between 95's and 90'/91's
 

Im 6'2" 240 my 91 seats feel fine

Re: Some Differences between 95's and 90'/91's
 

I could be wrong but The BIG Difference everyone overlooked so far is The 95' Comes from GM with R134 AC System.

All the 90's and 91's and maybe up through the 94' had R12 AC.

Post #1 has been UPDATED.

Re: Some Differences between 95's and 90'/91's
 

94 was the first year ZR-1s switched to R134

Re: Some Differences between 95's and 90'/91's
 

That would be interesting to Note the Changes from 94' to 95' :thumbsup:
Changing from R12 to R134a is a pretty BIG change as is the ALDL Plug Pin Out.

Also.....have not looked closely yet but......are there any changes in the Thermostat Housing and the associated Heater Hose Connections?

Never understood the way those Heater Hose Connections Functioned without leaking ;)

http://i287.photobucket.com/albums/l...539378393a.jpghttp://i287.photobucket.com/albums/l...flowcrop-1.jpg

Re: Some Differences between 95's and 90'/91's
 

The seal is internal to the housing #40 in your image. Your next visit to an AP store ask to look at a Dorman 800-401 or their equivalent to a GM #24503682 and you'll better understand. There were no changes that I recall to end of production. Instead of the seal being added to the pipe as in Saginaw style fuel and power steering fittings the seal was included into the coupling. Operation is nearly identical.

Re: Some Differences between 95's and 90'/91's
 

I prefer to call them smuggling compartments.

Re: Some Differences between 95's and 90'/91's
 

I would like to add that the later cars have a modified footwell and there is more room around the clutch pedal and 94-96 cars don't have the tore-up carpet problem quite like the early cars on the dead pedal hump.

-another observation I had with my 95 is the dimmer switch dims the gauges anytime, not just when the headlamps are on.
-how about another... a/c works in all vent positions, not just recirc and forward ventilation.
-I also would point out that the digital gauges on the 94-96 C4's also have the oil temp and water temp digital display in addition to the analog gauges. I think the trip/range button arrangement is also different (more functions).
-Lets not forget that the later cars have white gauge face ink because older eyes can see the contrast better than orange on black- especially since the dimmer doesn't work unless you have the lights on, lol.

Re: Some Differences between 95's and 90'/91's
 

Yes.....:p.......very interesting.......thanks :cheers:
I am finding out other items as well......I will update the list after I get my C4 Beam Plates installed tomorrow ;)

Re: Some Differences between 95's and 90'/91's
 

Interesting list Cliff

What is different here?

Re: Some Differences between 95's and 90'/91's
 

You have to ask Demps as he had it on his list.

Re: Some Differences between 95's and 90'/91's
 

Can toggle digital readout for "gauges":
--oil temp
--voltage
--coolant temp

Ted

Re: Some Differences between 95's and 90'/91's
 

Wheels?

Re: Some Differences between 95's and 90'/91's
 

if we are talking about wheels then tire tread pattern also.
goodyear gatorback---vs---goodyear eagle gsc

Re: Some Differences between 95's and 90'/91's
 

Also, I believe 1990 was the only year for the 2 vertical gills.

Re: Some Differences between 95's and 90'/91's
 

95 seat belts unique
95 seat seam-stitching unique (double French)