Banana_Z52

Oh, my woes with the new car continue.

My 87 4+3 has 58000 miles. I picked it up a few weeks ago. It shifted great when I got it, nice and smooth, no clash. I recently changed all the fluids, including the tranny fluid. I used exactly what it called for in the book-- 80W, GM, right from the dealer. After the fluid change, the tranny clashed/ground bad going into second, especially when cold, unless I double clutch. 3rd also had a bit of clash. Again, the tranny exhibited none of this behavior with the old fluid. Per the shop manual I tried adding a bottle of posi additive, and the problem got a little better, but it was still pretty bad.

I decided to try some Redline MT-90 last week at the recommendation of a friend; the tranny is now MUCH better, especially when cold, but still not as good as when I bought the car. It still has slight clash into 2nd gear when cold, a tiny bit when warm, and 3rd has a tiny bit of clash when warm.

Any further suggestions of what to try? What are you running in your 4+3?

Also, is GL4 or GL5 recommended for this gearbox? The owners manual says GL5, but the service interval / maintenance items pamphlet says to use GL4. I know GL5 contains some sulfur compounds that are hard on "yellow metals" like brass and bronze (i.e. syncros). The Redline MT-90 I'm currently running is recommended for GL4 applications.

Thanks,
Troy


[Modified by Banana_Z52, 8:54 PM 1/31/2004]

scorp508

I use...

4-speed: 75W90 Mobil 1 Synthetic Gear Oil
Overdrive: Mobil 1 Synthetic ATF

Rich B.

The *shop manual* says to add posi additive to the trans??? Thanks for pointing this out! I must have missed it...Can you give me the page number for that??? I'd appreciate it...(Is that for the O/D or the gearbox???)...

I use Valvoline 90 wt gear oil in the trans and Dexron III ATF in the O/D...

(My '86 has 112+ miles)...


[Modified by Rich B., 8:39 AM 2/1/2004]

scorp508

Hmm... I never noticed anything about posi additive. I don't quite understand what it would do in there compared to the diff.

Banana_Z52

Just to clarify on the posi additive: the shop manual states to add it if needed to help a shift effort problem. It doesn't say add it outright, but only add up to one bottle if necessary to help with shift effort. It's right in one of the first couple of pages of the tranny section, 7B-6, bullet #4 under "Transmission Shift Effort Diagnosis." I overlooked it the first time I read through. The issue is moot if you run a fluid which already has the Posi additive (AMSoil, Redline, etc.)

Can any of you guys clarify if you are running GL4 or GL5 oil?

I'm almost tempted to drain and save my GL4 rated MT-90 (specifically for trannies) and try some Redline 75w-90NS GL5 (for rear ends, without the posi additive) and see if my problems get any better. Again, the books are confusing. One says to use GL4, another GL5... and there are pretty substantial differences between the additive packages in each fluid.

Troy


[Modified by Banana_Z52, 12:33 PM 2/1/2004]

CentralCoaster

I'm just running some Valvoline dino ATF crap, with stop leak additive.

The 4 speed has non-synth valvoline 75w90, with some Lucas.:( Lucas makes the shift effort difficult until it's warmed up. I wouldn't recommend it unless you're lazy or ignorant.

I tried redline, and Mobil 1 in the overdrive and 4 speed, but couldn't get em to stay inside the units. I don't want to try my luck with those again.

Everything works fine though. I keep the fluids fresh and check them often.

Rich B.

...So it is...I missed it three times through... :bb

...Good to know!...

Sharp eye, Banana_Z52!!! :thumbs:

Banana_Z52

Thanks for the info guys on what you are running... but can anyone let me know if I should be running GL4 or GL5 fluid?

Just got back from a quick 40 mile drive... while the car shifts pretty easily once it's warm I still don't like that minor "grating" feel though the shifter as I select 2nd and 3rd. I really want to get this thing cleared up (aka back the way it was BEFORE I change the fluid!) Last time I ever perform maintenance on my car. LOL!

Troy

byte_me

What does the clutch fluid look like? I did the same thing as you on my 38K 4+3 and it shifted like butt! I used Mobile 1 Synth in the 4 Speed and Redline Synth in the OD, I noticed the thing actually went in and out of gears better but it was PITA cold...I looked at the clutch fluid and noticed it has some thick black fluid in the bottom of the cup...so I pulled both master and slave off to clean and flush them...(note: my tranny would grind going into 3rd and it never did this before) after cleaning and bleading the system....it shifts like new!

Maybe something for you to look at...the bleading was pretty easy as long as you keep the master cylinder cup full of fluid! :-)

Hope this helps!

:cheers:

Banana_Z52

byte_me: I put a new clutch master and slave cylinder on soon after I bought the car, as the master took a dump in my driveway after the 20 mile drive home after I bought the car :crazy:

I don't think any of the replacements are bad, as I can hold the clutch in for >60 seconds and it doesn't bleed down and try to start the car rolling.

It has to be something about the tranny fluid I'm using because when I double clutch and manually do the work the syncros would normally do, my clash issues go away completely.

Troy

Banana_Z52

Just a follow-up for myself and anyone else...

Problem solved!

I picked up some 80w-90 GL5 from the GM dealer today, drained my Redline MT-90 with 200 miles on it, and voila! All 2nd and 3rd gear clash is now totally gone, and the shift effort has dropped dramatically. It's better than when I bought the car.

It's slightly stiff for the first few miles when cold, but most importantly: no clash even when cold. Once warmed up, the shifting is nice and smooth with no grating or clash felt through the shift handle.

Also an FYI-- while researching the problem I read through the tech archives over at 5speeds.com-- the admin over there used to rebuild of 4+3s (until selling the stuff to SKspeed recently) and also claims to have been one of the builders for the 4+3's in the Callaway turbo cars. He says NOT to run synthetics in these boxes, and cites abnormal shifter fork wear and also cracks in the syncro rings as a result of using synthetics.

I'm just elated I can drive the thing again without timid shifting and/or double clutching!

Troy


[Modified by Banana_Z52, 7:57 PM 2/3/2004]

scorp508

Ahhh yes.... I have read that also. There are varying opionions on fluid. David-F is another huuuuuuge 4+3 expert and I believe he has said synths are ok. Brian at SKSpeed I think (don't quote me though) has also said synth is ok.