5-Speed Manual Downshifting Issue

[BD_Designs]

Hello All!

I am thrilled to be joining the DMC community and am the proud new owner of an '81, 5-speed model. This is the first time I've ever owned, driven, or even ridden in a DeLorean and it's a dream come true to own one finally!

After taking it out for my first drive yesterday evening, I noticed that the car seems to be having a few issues downshifting, mostly into first gear. It downshifts quite smoothly in between the other gears. It doesn't have difficulty every time but on a couple of occasions when trying to bring the shifter up into the first gear position, it felt like it just hit a wall and wouldn't move up. When it did allow me to move it properly into place, it seemed tight. Are the DMC 5-speeds typically tight in getting into each gear or should it be more fluid?

I tried searching the forum for some similar threads addressing this and thought that it might be a linkage problem, but it seems odd that it upshifts very well and downshifts through most of the other gears great as well, with the exception of first.

Luckily I am located in the Houston area so at least I have DMCH here as a resource (albeit I'm way on the other side of town from them), but I just wanted to try to troubleshoot this myself with the community's help before having to take it to the shop. Are there any other Houston-area 5-speed owners that might be able to provide some insight?

Thanks for the help and it really is a joy to be joining this community!

-Blake

[Mark D]

Hi Blake,

Welcome to DMC ownership!

I don't typically downshift into first until the car is rolling at less than 10mph, usually if I'm coming up to a stop sign. Otherwise I downshift to second for engine braking until the car is at a low speed and then go into neutral the last few feet until I have to stop.

Depending on the speed you're driving what you're experiencing might be somewhat normal. If you're not already familiar with what's going on inside the transmission, before you can physically shift the transmission into any gear the synchro ring for that gear is used to speed up the gear so it matches the speed of the rotating shaft. Once the speed of the gear and shaft are matched the gear can be slid into place with the selector rod and locked onto the shaft. If you're at a relatively high speed for that gear it may take a few moments of pressure with the shifter for the synchro to do it's job. It should just take a moment so if you're not able to downshift at all you may have an issue with the 1st gear synchro.

One thing you can try is to have the car in 2nd gear and coasting at about 25mph. Put your foot down on the clutch pedal and try to downshift into 1st. Let the car continue to roll and gradually slow down while you (gently) hold constant pressure with the gear selector against 1st gear. At some lower speed the shifter should finally engage to allow you to shift into first. At the very least once the car stops moving or is just barely rolling you should be able to get the shifter back into 1st. If you report back with the results that might help diagnose what's going on.

If you're experiencing issues in other gears besides first it could be possible that your clutch hydraulics are not fully disengaging the clutch when you step on the pedal. When you're pushing down on the clutch at what point does it disengage? Is it at the top of the pedal stroke or the bottom? If it feels like you have to have the pedal almost all the way down then you may have air trapped in the clutch hydraulic line, or an issue with either the master or slave cylinder.

You can check the reservoir for fluid level inside the trunk by removing the carpet and access plug. The fluid color should be a honey colored/light amber if Castrol GTLMA was used, or almost clear if some other DOT 4 clutch fluid was used. Anything darker than that indicates the fluid is getting old and may point to some kind of issue with the hydraulic system.

To check for issues with the master you can look for leaks near the pedal where the piston is visible for the clutch master. Leaky master cylinders usually are evident by fluid leaking down past the bulkhead around the carpet area. I'll try to find a photo so you know what to look for.

EDIT: here's what a leaking master cylinder looks like. It's located by your feet next to where the steering column passes through the front bulkhead.
http://dmctalk.org/attachment.php?attachmentid=35397&d=1436818777

The slave cylinder (mounted to the transmission) is a a little harder to get to, but you may be able to visually see that the bell housing on the engine is wet with fluid, by looking over the top of the engine.

One final thing to check is that your hydraulic line that connects the master cylinder to the slave cylinder has been updated to a stainless braided line from the standard plastic/orange line from the factory. The stock line tends to expand when warm so that the clutch will not fully disengage even with correctly working master/slave.

There are definitely people here with more hands on experience diagnosing transmission issues than I have, so I'd expect so see some other suggestions posted here as well.

[Bitsyncmaster]

I don't down shift into first until I'm stopped. My car has always been hard to get into reverse. More than 50% of the time I need to just let the clutch up in neutral and then it will go in reverse. I never use force to change gears.

[BD_Designs]

Mark/Dave,

Thanks very much for the excellent information and for giving me a rundown on how the transmission should be properly functioning in these cars since I am not familiar with what might be normal for them just yet.

This particular car was restored about 8-9 years ago and in the paperwork I have for it, I believe I did see where the hydraulic line was upgraded to the stainless braided line as has been recommended, so I don't think it's a problem with the stock line expanding, however you did mention the clutch being completely on the floor and I noticed that, yes, there were instances where it felt like the pedal was nearly all the way to the floor.

When I get home this evening I will check to see if there might be a leak coming from the master cylinder. I don't recall seeing anything when I was cleaning the car, but I will look again now that I know what to be looking for. Otherwise, there don't appear to be any leaks coming from the car and everything else seems to be working well.

It really is a wonderful car and I think it's going to be a joy to own for many years to come!

[PJ Grady Inc.]

Mark/Dave,

Thanks very much for the excellent information and for giving me a rundown on how the transmission should be properly functioning in these cars since I am not familiar with what might be normal for them just yet.

This particular car was restored about 8-9 years ago and in the paperwork I have for it, I believe I did see where the hydraulic line was upgraded to the stainless braided line as has been recommended, so I don't think it's a problem with the stock line expanding, however you did mention the clutch being completely on the floor and I noticed that, yes, there were instances where it felt like the pedal was nearly all the way to the floor.

When I get home this evening I will check to see if there might be a leak coming from the master cylinder. I don't recall seeing anything when I was cleaning the car, but I will look again now that I know what to be looking for. Otherwise, there don't appear to be any leaks coming from the car and everything else seems to be working well.

It really is a wonderful car and I think it's going to be a joy to own for many years to come!

While you're at it check the slave cylinder too. It's mounted on top of the trans. bellhsg and can be checked by looking down at the trans. from the engine bay forward bulkhead and the fuel distributer. They fail about twice as often as the mtr. cyl. due to close proximity of the crossover pipe.
Rob

[BD_Designs]

Will do! Thanks for that tip Rob!

[David T]

Will do! Thanks for that tip Rob!

Since the car is new to you one of the first things you should do is check ALL of the fluids. For the transmission you should check the level but if you do not know exactly what is in there or the last time it was changed, you should be removing the old stuff and refilling with something good like Castrol 85W-90 Hypoid C. Remove the level plug first BEFORE you touch the drain plug. That way if you can't get the level plug loose you are not left with an empty transmission that you can't refill. Get the adapter so you don't damage the plugs. The linkage may need a tiny bit of adjustment, cleaning, and lubrication too. Most drivers will downshift into 1st only when coming to a stop or starting from a standstill. If you are rolling use 2nd.

[BD_Designs]

Great tips! Thanks David.

The car was well-taken care of by the previous owner and I believe it was serviced not long ago. But I agree, I should go ahead and check everything just to be sure.

[BD_Designs]

Okay so I checked a few things on the car this evening... The hydraulic fluid reservoir was full, a perfect amber color, and there was no seeping around the clutch pedal at the bulkhead so it does not appear to be a leaking master cylinder.

I also did a little test with the clutch and shifter while the car was parked and turned off. I tried shifting the car through all of its gears and the shifter moved very fluidly upshifting, downshifting, and going into reverse with no tightness, hesitation, or sticking. It felt perfect. So it seems like the linkage is alright from what I can tell...

[BD_Designs]

Sorry to dig up one of my old threads, but I wanted to get some tips on troubleshooting what now appears to be a clutch master cylinder issue on my car.

Over the past year since I first started having these intermittent shifting issues, I now have absolutely no pressure in my clutch pedal when it is depressed and I am trying to narrow the issue down to either the master or slave cylinders since one is a lot more difficult to change than the other.

As the car sits right now, the clutch will not engage at all and is totally dead, to the floor, when it is pressed. There still are not any signs of leaking fluid around the pedal/floorboard area so it's tough to determine if the master cylinder is the one that is bad. This past weekend, I tried bleeding the slave cylinder in hopes that maybe it would clear some air out of the line, but upon opening the bleeder valve nearly all the way, not a single drop of fluid came out. There are also no signs of fluid leaking from the car either in the front around the master cylinder or in the rear near the slave.

So, under these conditions, I'm wondering if the master cylinder might be leaking internally, as has been suggested, but my question is would an internally leaking master cylinder prevent any fluid from getting back to the slave, which is why nothing came out while bleeding it? I imagine that if the master cylinder had an internal blockage, then this would prevent any fluid from getting back to the slave, correct? Would it also completely kill the clutch and cause it to have no pressure as I am experiencing as well?

I would appreciate any feedback you guys might have in regards to if I should start with replacing the master first since that is easier to access and change out or if these issues lean more towards the slave being bad? The master cylinder was last changed in 2007.

Thank you kindly!! I appreciate everyone's help and am glad to be learning this stuff so I know what to look for in the future.

-Blake

[David T]

Figure on replacing both cylinders. Clutch and brake fluid must be changed every other year. If you don't then it corrodes the cylinders and they leak. While you are at it you should flush and bleed the brakes too. New brake fluid is almost clear. If it starts to get dark it is past due for a flushing. Amber is already time. If you don't want to do the cylinders let DMCH have all of the fun. Pull the carpet up on the diver's side and check for brake fluid. Look under the rear of the car for signs of leaks. If you are not leaking any fluid and have no clutch pedal, the clutch master is probably bad but I still advise replacement of the slave too.

[BD_Designs]

Thanks David! Sounds like the master cylinder is a good place to start.

I am definitely glad to have DMCH nearby in case I ever need to bring it in. Just want to do what I can at home first before having to take it there. Replacing the master cylinder seems to be manageable but when it comes to the slave cylinder, I might let them tackle it.