This has now happened to me a few times: I'll be driving along in 7th (4+3) and accelerate to pass. The car kicks out of OD (like it should) but it seems like its going into neutral....the car just revs but no power is going to the wheels. Anybody else had this problem? Any ideas to fix it?

I also will need to have the clutch rebuilt this summer (starting to slip a bit). It's never been touched and I think that's pretty good for a car that's almost 20 years old. My question is where to get it fixed. I'm the only one in the Windsor Corvette Club with a C4 that isn't automatic, so nobody can help. I've called a few transmission shops but they don't even know what a 4+3 is. I'm willing to go anywhere in Ontario, Michigan or Ohio.

 

Sounds like low fluid in the OD section of the DN4+3. Check the OD fluid level. As for the clutch replacement, this trans is basically the same as any other T10 clutch replacement. Very straightforward, pretty easy.

Aaron

 

Could it be your clutch slipping? If there is a nasty smell along with the rev, that is probably it.

My clutch is almost 100% gone now, if I rev the engine in any gear (stomp the accelerator) the revs go up, but the tires don't spin.

 

That could be it as well. But if the clutch is that far gone, you probably should not be driving the car any longer. Kinda FUBARs the flywheel when driving with a "gone" clutch.
Aaron

 

IF you think that the clutch is going out, you should be seeing some amount of grinding when goiung into reverse. Reverse gear doesn't have a synchro so if the input shaft is still turning when the clutch pedal is depressed, that gear will not mesh without some grinding.

A clutch replacement on the 4+3 is not that difficult to do and a good shop should be able to do the job. A new clutch, plressure plate and throwout bearing is installed as a set and the flywheel should be refaced to get a new surface.

As mentioned, the 4-speed portion is simply a Borg-Warner Super T-10 so the job should not be that difficult. Figure about 3-4 hours labor and whatever the parts cost depending on what clutch setup you want.

The tranny comes out as a unit and the bellhousing is removed like any other SBC. The shifter is bolted to the car and the C-beam does not need to be removed.

I would definitely have the fluid in the OD unit flushed and replaced. Replace the gear oil in the 4-speed too. Use Dexron II or III in the OD. If you haven't replaced the gear oil in the diff, do that too. Add a couple bottles of the GM posi additive.

There is a filter in the pan and the filter is the same one as used on Ford FMX trannies. Don't bother with buying one in the Vette catalogs for $20 or so. The FMX tranny was found in mid-to late 70's Torino's, Merc Cougar's, some F150's and Fairlanes. Expect to pay around $6 for one at any parts store.

 

Thanks for the input. I do have grinding going into reverse, so its time for a new clutch. What would you recommend? I've heard not to go with the stock clutch but to upgrade it, but I can't see the point since its lasted almost 20 years. What would it cost to replace the clutch?

 

The type of clutch that you get may depend on the kind of driving you do. Do you drag race? Autocross? Do track days? or just street driving? CenterForce makes a good clutch as does Luk or even go with a GM replacement setup.

Just make sure that the flywheel is resurfaced and you get a new throwout bearing. A good shop will check the condition of the pilot bearing in the rear of the crank and replace as needed.

Figure on $700-$900 depending on the shop.

 

A stock clutch is perfectly fine for stock power levels in all conditions.

 

The stock 4+3 clutch has more clamping force than the ZF6 clutch.

I wonder if the Callaway used the stock clutch.

 

It did.