TheClairvoyant

The 86.5 has a different exhaust set up too, doesn't it?

LEADASS

I think that the exhaust is the biggest part. My early '86 can't run true dual but I think that the '86.5 can run the S4 dual. The battery box is in the way. The brakes and suspension can be easily upgraded.

Mr. Piff

Are the interiors of 86.5, the same as an S4?

Landseer

Short battery box.
Less teeth on antilock counters & different antilock brain pgming and harnesses.
Front sway bar, link, upper and lower ctrl arm, brakes
Aluminum bolt in mounts (vs uni body welded), for rear toe adjustment and control arm
Rear jack points protrude.
Dual catback
Mounting difference for muffler hangers on body and rear xmember

Not sure what else, am disassembling one in garage next to a pure early 86 right now.

Early 86 did have rear hatch third brakelight based on my experience.

Not sure of many interior differences, other that covers at rear foot well covering bolts for the lower control arm mounts mentioned above. Different antilock harness routing and ground point in rear, like S4 I think.

PorKen

'85
- 32V USA
- ABS option
- alarm option
- revised seats
- rear air option
- windshield antenna
- revised LSD ('4-disc')
- revised manual trans
- TB 'tension warning light'

late-'85
- diag plug moved forward
- revised center timing belt cover
- revised dipstick tube (bolted to cover)
- revised cam gears with large front TDC notch
- revised, more easily removable left timing belt cover
- revised left TB cover breather moved forward, w/TDC nub


'86.0
- ABS standard
- alarm standard
- third brake light
- revised bulb brain
- revised cam tensioners
- revised manual gate spring
- FPR return hose repositioned
- revised timing belt tensioner (5mm centerline shift)
- revised right TB cover, breather moved forward, w/TDC nub
- revised cam gears w/10mm holes (factory left install alignment?)


'86.5
- 32V ROW option
- revised jack points (rectangular)
- revised differential oil plugs w/seal
- revised LH computer (yellow motherboard)

true dual exhaust
- larger exhaust pipes (52mm vs. 49 ID)
- revised floor pan (shallower rear seat bottoms)
- bolted, cast aluminum, rear toe arm mount
- revised rear x-member
- smaller battery/box
- fuel tank heat shield
- autos, extra drain plug under differential
- autos, revised trans fluid tank w/heat shield
- RMB-able rear muffler

4-piston brakes
- Brembo calipers
- revised brake hoses
- no phone dials
- revised a-arms
- revised ball joints
- larger front hub bearings
- revised ABS brain/tone rings (lower tooth count)
- weatherproof ABS/brake wear sensor connectors

Landseer

There we go... add the front sway has different bend/configuration where it contacts the links, link length is different, tie rod length... to kens list.
(shop manual will detail this for anybody interested)

Ken: Can a manual computer be used in an automatic without chip change?

PorKen

No difference in stock LH or EZ computers (or their chips) for auto or manual.

Pre-'86.5, there was an option to code for automatics, but it was not wired into the LH plug ('86.5 m-board components not installed).
This would disable injector cutoff on deceleration, which keeps the torque converter 'spooled up', for better response.


In practice, autos have a different effective gear ratio because of the torque converter (heavier too).
This changes the RPM/load calculation - generally, manuals 'need' less fuel (injector time) than autos at the same RPM.



S300s LH chips are made for auto or manual. They should not be switched.
Manuals can use autos' in a pinch, though.

jbrob007

Ken, Thanks for the listing... Damn, quite a few differences for sure! I feel better and better everytime I learn a bit more about this 86.5 I literally stumbled over and bought!

Are there going to be any new performance items or improvements? Or have you turned your attention to the 87 & newer model years?

PorKen

I don't have any plans for S3s...how much more do you need?

I may think of something when I get to working on my '88 in earnest.


Since the weather has been bad, I've spent the last couple of months working on my '85 GMC 3/4 ton 6.2L diesel (C6P heavy duty option).

I put in a Doug Nash DNE² dual-range aux trans (4.10/3.28 ratio), bolted to a TH-400, then a full floating 14 bolt rear axle (10.5" ring gear) w/G80 locker from a early-'84 Suburban.

jbrob007

"I don't have any plans for S3s...how much more do you need?"

All that we can get!!! I think you left 1 or 2 HP on the table somewhere...

rexpontius

I am also really happy I bought an 86.5 :-) and I also more or less stumbled upon it. Found out it was a rare one after I bought it :-)

Imo000

Apperantly the timing belt covers are slightly different too and thee is an solenoid on the crossbrace.

Vilhuer

32V 9.3:1 CR engine was available from begining of '86 MY. First car made with it is VIN GS840070 meaning already 10th ROW '86 made was with M28/45 engine. AFAIK every ROW '86 16V and 32V had all (or at least most) of the changes made for '86.5 US cars.

whiteNSXs

There are small differences in switches but most significantly the rear seat back middle hinges are on the rear console in 86.5. The S4 has the middle hinges moved to the anterior part of the trunk. 1988+ have rear shoulder belts.
Steve

Vilhuer

In some ROW markets already late MY S have them and AFAIK all bodies have mounting points ready for them.