Level of Difficulty DIY 1988 Carrera

[Skepa122]

Hello,

I have a rather unique issue with my 1988 Carrera. As the car warms up, the transmission becomes more difficult to shift between gears, especially in the horizontal plane. I find that when the engine and presumably transmission get warm, I lose the self centering ability of the stick shift and getting between gears becomes difficult (for example moving from 2nd to 3rd).

Having done some research, some people have suggested changing part #25 in the attached diagram.

How difficult of a job is this for a DIYer? I understand that the transmission and engine would need to be dropped? How deep into the transmission would you need to get? Maybe if I have to ask, it is better I not attempt....

Have tried all the regular fixes and cannot get this resolved, including changing all bushings and running different tranny fluid. Car has 123,000KMs so it isn't super high mileage.

Thanks for the input.

[dannobee]

I seriously doubt that the #25 bushings will fix your problem, but if you insist on changing them, you'll need to drop the trans, remove the tail shaft, the two shaft nuts #18 and #21 from the gears and shafts page (22mm and 41mm, IIRC), the reverse switch and pin, 5th and reverse gears and synchros from the input and pinion shafts, along with the 5th/rev shift fork, then remove the intermediate trans case. After that you'll need to remove pin #15 and shaft #4 before slipping out shift lever #2. Ball #13 and spring #12 will then fly across the shop at eye level while springs #5 and #6 (two different sizes and not interchangeable, btw) will simultaneously exit in opposite directions. BTW, shift lever#2 engages with shift shaft #1 and shift lever #2 from the shift rods/shift forks page and needs to be removed (and installed) at the same time.

Before I did any of that, I would separate the aluminum "bearing body" #16 from the Transmission Control page first and isolate the problem with the transmission still hot and narrow it down to either the shifter or inside the gearbox.

[Skepa122]

Originally Posted by dannobee

I seriously doubt that the #25 bushings will fix your problem, but if you insist on changing them, you'll need to drop the trans, remove the tail shaft, the two shaft nuts #18 and #21 from the gears and shafts page (22mm and 41mm, IIRC), the reverse switch and pin, 5th and reverse gears and synchros from the input and pinion shafts, along with the 5th/rev shift fork, then remove the intermediate trans case. After that you'll need to remove pin #15 and shaft #4 before slipping out shift lever #2. Ball #13 and spring #12 will then fly across the shop at eye level while springs #5 and #6 (two different sizes and not interchangeable, btw) will simultaneously exit in opposite directions. BTW, shift lever#2 engages with shift shaft #1 and shift lever #2 from the shift rods/shift forks page and needs to be removed (and installed) at the same time.

Before I did any of that, I would separate the aluminum "bearing body" #16 from the Transmission Control page first and isolate the problem with the transmission still hot and narrow it down to either the shifter or inside the gearbox.

Thanks for the reply.

I did disconnect the shifter from the transmission after the car was warm at the center tunnel between the rear and front seats (by lifting the cover and disconnecting the two bolts). When I did this I found that the shifter was easy to move back and forth which led me to believe the issue was in the transmission.

Is there anything else that I can try that is relatively easy access? It sounds like I would need to rebuild the transmission otherwise.

[FA-18C]

Before tearing into the transmission itself, I would first go back in and make sure that if you replaced the shifter bushings and ballcup etc, that you did not inadvertently get something mis-aligned, or not installed correctly. I would also take a look a the transmission bushings to check their condition. Admittedly no an expert in setting up the G50 with the shift rod, but I am sure someone will chime in. It is worth pouring through the Bentley's to see if it addressed setting things up following engine removal and install. Worth spending half a day.

[Skepa122]

Originally Posted by FA-18C

Before tearing into the transmission itself, I would first go back in and make sure that if you replaced the shifter bushings and ballcup etc, that you did not inadvertently get something mis-aligned, or not installed correctly. I would also take a look a the transmission bushings to check their condition. Admittedly no an expert in setting up the G50 with the shift rod, but I am sure someone will chime in. It is worth pouring through the Bentley's to see if it addressed setting things up following engine removal and install. Worth spending half a day.

Feel like I have the bushings correct and as for the shifter assembly, there is an alignment that I followed to position the assembly correctly. Not sure what else I can check.

I haven't checked the transmission mounts.

[dannobee]

Did the problem just recently start? Have you owned the car since new? Does the trans look like it's ever been apart (is tectyl still coating the bottom)?

What oil did you put in it? G50's call for synthetic 75w-90 GL5 oil.

[Skepa122]

Originally Posted by dannobee

Did the problem just recently start? Have you owned the car since new? Does the trans look like it's ever been apart (is tectyl still coating the bottom)?

What oil did you put in it? G50's call for synthetic 75w-90 GL5 oil.

I have had the problem for the last couple years, I have had the car for 7 years now and when I first got it and drove it frequently I did not notice this issue. In the last 3,000KMs or so is when I have started to notice it.

I changed the transmission fluid twice and the last time I used Delwac 75w-90 (if memory serves me correctly).

I don't think the trans has ever been apart. I did do a bunch of cleaning on the bottom end when I restored my rear suspension so I cannot recall the tectyl coating.

When the car is cold and when you first get going the shifter feels very good and operates normally.

[dannobee]

You've covered the easy stuff first? Trans mounts aren't sagging, allowing the shifter shaft to touch the body? Clutch is bled and free of air? Shifter shaft isn't hitting something in the tunnel?

I can't really see the bushings in the shift lever (#2 in the pic) binding up. If anything, they would tend to get looser with age/use, not tighter.

[Skepa122]

Originally Posted by dannobee

You've covered the easy stuff first? Trans mounts aren't sagging, allowing the shifter shaft to touch the body? Clutch is bled and free of air? Shifter shaft isn't hitting something in the tunnel?

I can't really see the bushings in the shift lever (#2 in the pic) binding up. If anything, they would tend to get looser with age/use, not tighter.

I'll have a look at the trans mounts again, they looked pretty good when I had a chance to see them, will try and see if the shaft is touching the body.

I haven't bled the clutch. Could this cause the shifter to be stiff side to side after warmup?

Will recheck the tunnel and see if the shaft is hitting something there.

Thanks for the input

[Marine Blue]

It’s a long shot but I was also going to suggest bleeding the clutch as it’s always forgotten and can get pretty nasty! Here’s what came out of mine, I have no idea when it was last flushed. Before the flush I noticed that the clutch pedal was sticking at the bottom when the car got really hot, that has been resolved after the flush. Either way it’s something that should be done if it’s been more than 3 or 4 years.

[Skepa122]

I'll definitely bleed the clutch as it is a part of the maintenance that is overdue.

With that said, am wondering how it could stiffen up the shifter itself in the horizontal plane? The shifter after it is warm is harder to move side to side whether I am on, or off the clutch. Simply moving it in neutral becomes harder when the car is warm.

It is a good suggestion to do this maintenance though!

[Marine Blue]

I agree it’s unlikely the issue unless the slave is not allowing full actuation which again is unlikely.

[porschyard]

Originally Posted by Skepa122

Hello,

I have a rather unique issue with my 1988 Carrera. As the car warms up, the transmission becomes more difficult to shift between gears, especially in the horizontal plane. I find that when the engine and presumably transmission get warm, I lose the self centering ability of the stick shift and getting between gears becomes difficult (for example moving from 2nd to 3rd).

Having done some research, some people have suggested changing part #25 in the attached diagram.

How difficult of a job is this for a DIYer? I understand that the transmission and engine would need to be dropped? How deep into the transmission would you need to get? Maybe if I have to ask, it is better I not attempt....

Have tried all the regular fixes and cannot get this resolved, including changing all bushings and running different tranny fluid. Car has 123,000KMs so it isn't super high mileage.

Thanks for the input.

You asked this same question in October of 2020 and I explained in some detail two previous gearboxes with the identical problems. Contrary to dannobee’s comments about the entire gear cluster needs to be removed and disassembled I explained how I removed just the shift mechanism assy W/O disassembling the entire box.

I guess the fact that you are asking the same question two + years later means your still looking for the issue. The stiffness is probably less pronounced in the cooler months and really bad during the summer on hot days after extended run time. Since my post and explanation on 10-18-20 I was contacted by another shop in south fla about the exact same problem and they performed the same replacement of the bushings I described using the same method of just removing the shift mechanism assy and reported back after a few months that that was the problem.

Good luck getting this resolved but I am 100% positive that your issues are the shaft # 4 seizing on the bushings # 25.

Having said all that the 3 gearboxes that I am aware of that this procedure fixed the problem were all low mileage boxes. Given that your box has substantially more mileage you might consider going through the whole box. If you want to confirm this diagnosis remove the tail shaft cover and center section housing and place a heat gun directly at the shift mechanism and periodically check the movement of the shift lever # 2 and you will find that the warmer/hotter it gets the stiffer it will become.

Also make sure to pay close attention to the return springs # 5-6 as they provide the tension for the neutral plane of the fork. I did not replace the springs on the 964 box as it was a low 34k mile box. I did however have a customer with a 95 993 box that was tracked and had a complaint about a very soft/weak side to side shifter resistance and it turned out those springs had been overheated and collapsed.

Richard

[Skepa122]

Originally Posted by porschyard

You asked this same question in October of 2020 and I explained in some detail two previous gearboxes with the identical problems. Contrary to dannobee’s comments about the entire gear cluster needs to be removed and disassembled I explained how I removed just the shift mechanism assy W/O disassembling the entire box.

I guess the fact that you are asking the same question two + years later means your still looking for the issue. The stiffness is probably less pronounced in the cooler months and really bad during the summer on hot days after extended run time. Since my post and explanation on 10-18-20 I was contacted by another shop in south fla about the exact same problem and they performed the same replacement of the bushings I described using the same method of just removing the shift mechanism assy and reported back after a few months that that was the problem.

Good luck getting this resolved but I am 100% positive that your issues are the shaft # 4 seizing on the bushings # 25.

Having said all that the 3 gearboxes that I am aware of that this procedure fixed the problem were all low mileage boxes. Given that your box has substantially more mileage you might consider going through the whole box. If you want to confirm this diagnosis remove the tail shaft cover and center section housing and place a heat gun directly at the shift mechanism and periodically check the movement of the shift lever # 2 and you will find that the warmer/hotter it gets the stiffer it will become.

Also make sure to pay close attention to the return springs # 5-6 as they provide the tension for the neutral plane of the fork. I did not replace the springs on the 964 box as it was a low 34k mile box. I did however have a customer with a 95 993 box that was tracked and had a complaint about a very soft/weak side to side shifter resistance and it turned out those springs had been overheated and collapsed.

Richard

Thanks for the confirmation. I was referencing your solution and was looking for anything else that could be contributing to the issue. In other words, looking for something that could be done within the realm of a normal DIY mechanic in a home garage.

Without the knowledge of G50 transmissions, I didn't know how far into the transmission I would need to dig to take care of the issue.

Getting time at a reputable shop in my area (Ontario Canada) is becoming difficult and expensive. Was looking to hopefully tackle this myself if possible.

[dannobee]

Well, there you go!

BTW, I never said he'd need to disassemble the shafts, just the nuts to get 5th and reverse gears off to get the intermediate housing off. The pin holding the shaft in (#15) can be removed with a pair of side cutters. The interlock/retainer plate can stay in place.

I suppose it could be related to an oil additive or something. Or a regional thing. Being here on the West Coast, we have little rust or wild temperature swings to deal with, so often times we'd hear different stories from techs from other parts of the country that seemed to be specific to their climate.

[Skepa122]

So it is sounding like I have to drop the transmission as there is no other way? Just perhaps don't have to go as deep into it as initially thought.