I traded for this 85 vette about 6 months ago. all gears seemed to work just fine. during a jiffy lube oil change they suggested a tranny fluid change with synthetic fluid. shortly after this the reverse seems to not totally grab the gear. alot of whining in reverse and not much power, in fact i now cannot back up on even a slight grade. any ideas from you veterans out there?

 

Which part of the transmission did they change, the Borg Warner 4 speed or the OD unit? The OD unit runs on automatic transmission fluid and the 4 speed runs on 80/90 weight gear oil. Neither side is designed for synthetics. If they put it in the OD unit that's a problem.

Jiffy Lube?

 

they changed the gearbox supposedly. not the overdrive. will the synthetic fluid cause the reverse to slip?

 

First things first. NEVER go to JIPPY LUBE for service on your 4+3. Most of those people don't know anything about these unique transmissions. Get a seasoned Corvette mechanic. Did they put the correct filter in it? These are special filters that I can gaurantee they did not have in stock. Also use a good quality Dextron III (non synthetic) fluid only. The transmission in regular operation (not in overdrive) should not be affected by the overdrive unit. It should go in all 4 gears and reverse with out anything to do with the O/D unit. Your slippage sounds like something to do with your regular 4 speed transmission. No biggie. Just get a good knowledgable transmission mechanic and you'll be back on the road quick. Good luck.

 

First mistake was going to Jiffy Lube for ANYTHING.

Now, what they did was they put synthetic gear-oil in your OD unit (atleast, that's my guess) because the OD fill and the 4-speed fill look very similar. I think the OD unit going bad can actually affect the non-OD operation. Atleast I've heard of it happening to others on the board. Does your OD work anymore either?

Good news is they likely just bought you a brand new $1700 rebuilt OD unit. Take it back and have them open the OD pan and catch what's in there. If it comes out looking like anything but nice red DexIII they screwed it up royally.

Other chance is the synthetic 4-speed oil is leaking profusely from your front seal and making your clutch slip. That's possible, but not being able to back up even a slight grade is more than just a little clutch slip.

 

Time to find the receipt. I have not used the overdrive, so i dont know if it is still working or not. I will try it out tonight. I should have known better than to use those jokers for anything out of the ordinary.

 

Slipping in reverse may be due to worn or oil-soaked direct drive clutch packs in the OD unit. Reverse depends on the direct drive clutch packs in the OD unit to work properly.

This could be due to gear oil seeping thru the seals at the rear of the 4-speed case. Synthetic gear oil can very well cause leakage at the rear of the case.

Find the slip and see what was done and what fluid was installed. I would bet that Gyppie Lube used a 75W-90 synthetic gear oil in the 4-speed portion.

I would not return to them to ask what they did and ask them to fix things. Go to a reputable shop (if you can find one that knows anything about the 4+3, the better!!) and have them troubleshoot and inspect the tranny and give you a written report on what they have found. Then go back to Jiffy Lube and ask to see the store manager. Not the daytime shift leader, you want the manager of the whole place.

Be prepared to go to the corporate or regional people to get this ironed out. You need to have some ammunition that shows that Jiffy Lube screwed up by installing improper fluid which directly caused the problems you are experiencing.

You may want to contact SK-Speed http://www.skspeed.com/ to see if they can offer advice or further diagnosis. They are knowledgable in the 4+3 and have both experience and parts for the tranny.

As mentioned, you do not want to use synthetics in either the 4-speed or the OD units. A good GL-5 80W-90 or 75W-90 gear oil in the 4-speed and regular Dexron II/III in the OD.

 

I wouldn't stop at a JL even for directions. Good advice on getting another shop to look at it. If they'll document what they find, including the cause I would, as mentioned go back and ask for the manager. If he starts to backpeddle, immediately ask for the number to their regional office. Dont waste time on him.
I was in a similar situation with Aamco and the best defense is a good offense...........trust me.

Keep us posted and good luck.

ps: they keep receipts for their records. This ain't a blender you're trying to return to Wal Mart.

 

If your going in armed for bear remember to save an oil sample (or two) for proof. There are oil labs that can verifiy what the fluid is.

But I'll be honest that 4+3 may have just picked this time to give up the ghost

 

od is done they might have put manual fluid in the whole trans od and gear box.Did they trans make a winning noise when the od was off?or now.If it did then the carrier bearing was going bad anyway.

 

I have synthetic fluids in both the trans and OD. No problems.
The fact that you are losing reverse tells me there is a good chance your OD unit is a boat anchor now.
Did they empty the OD and not fill it.

 

The fact that you have to drop the pan makes it unlikely they emptied the OD unit at all. I'd be more likely to believe the emptied the 4-spd part and filled it at the OD filler. You might not even ahve any oil left in the 4-spd part.

Definitely take it to a GOOD shop, preferably a corvette specialist, and have them lift it and drain the OD unit and the 4spd unit SEPARATELY into containers so you catch the fluids present in each one. I'm still betting the brownish oil/ATF mix comes out of the OD unit.

 

ok, I tried out the overdrive and it works. the corvette shop here in town refered me to a tranny shop that has experience with the 4+3. they will give the car a test drive this afternoon but i can't leave it with them to do service till next week. ( my truck is down and out for a few more days) am looking forward to hear what the tranny shop has to say but the corvette shop had nothing good to say about the 4+3.