Downshifting Problem

[mgpcpa]

I've recently experienced a problem with the 4-speed manual in my '71 280SL. When downshifting from 3rd to 2nd, the shifter needs to be pulled on hard before it goes into 2nd gear (when it goes into gear, no grinding however) . I want to avoid any damage by doing this, so I've been double-clutching and it goes into 2nd OK. All other shifting is fine, up and down (although notchy at times). The car is all original (89,000 miles) and the transmission has yet to be rebuilt. Any opinions would be appreciated. The only other trans problem that I've lived with for 18 years is that, when engaging reverse, I must go from 1st gear to reverse (not neutral), otherwise it grinds. 

[Tyler S]

Both issues are somewhat normal with a sticking pilot bushing. Esp the grinding going into reverse. Your doing the right thing putting it into first gear before reverse. This stops the input shaft from spinning and allows the gears to mesh without grinding.
The hard 2nd gear downshift is likely the same issue. Double check your clutch free play, master cyl and hydraulics, and adjustment to make sure your clutch is completely disengaging when depressed.

[ja17]

Observe the speedometer when you decelerate. If it jumps or bounces, you may have a loose slotted nut.

[Benz Dr.]

I had one in here this spring that wouldn't go into first gear. I changed the top shifting cover and it was perfect after that.
I've also found that too much end play on the input shaft or worn syncros can cause hard shifting but this usually involves grinding while changing gears. I also recommend synthetic ATF which aids greatly towards smooth shifting.

[mgpcpa]

Thanks for the reply and, yes I've used synthetic fluid in my trans for years. My tech is thinking it might be a sticking pilot bushing.
Mark from Suburban Philadelphia

[mgpcpa]

Greatly appreciate the reply! Hopefully the trans won't need a total rebuild.

[mgpcpa]

Thanks, Joe! Hopefully I can make the biennial Blacklick event next year. I wonder how many hours from suburban Philadelphia to Blacklick?

[Benz Dr.]

Thanks for the reply and, yes I've used synthetic fluid in my trans for years. My tech is thinking it might be a sticking pilot bushing.
Mark from Suburban Philadelphia

What does he base that on? Our cars use a small bearing rather than a bushing but I've not seen one cause shifting problems. I did see where one was seized and it wore the end of the input shaft where it fit into the bearing. This caused the shaft to deflect in high gear resulting in fourth gear popping out under hard throttle. This was on a 190SL but the parts are similar enough that I think it could happen in a 113 under the right set of wear problems. 

[Tyler S]

If the pilot bushing/bearing is hanging up, the syncro's work overtime to try to match the speed of the input shaft and main shaft. Is why it feels hard or notchy. Same goes for reverse. If the clutch is adjusted properly and fully disengaging then the input shaft should not be spinning. The grinding in reverse is caused by the hanging pilot bushing/bearing turning the input shaft. There is no syncro on the reverse gear so it grinds. Putting it into first gear before reverse temporarily stops the input shaft from spinning. A good test to confirm the pilot bushing/bearing is bad is start the car in neutral. Depress clutch and shift to first, then reverse. = No grinding. Now do the same test but wait 10 or so seconds in neutral in between shifting from first to reverse with clutch still depressed. Grinding now? = pilot bushing/bearing. The issue may not be necessarily the bearing but the grease in it has turned hard or lack there of. Some used to lube them with regular axle grease- big no no. Needs a high temp type grease or it melts off.

[Benz Dr.]

Never heard of that, or, I'm learning something new every day. 

  Original bearings were often open with no grease retainers on them. I now use a sealed bearing for that application figuring it should last longer. At any rate, I always replace them during a rebuild. Cheap insurance for 10 - 15 dollars.

[Tyler S]

Dan, I base my experience on this one remembering my Dad had this problem. He had the clutch replaced and pilot brg. Fixed the issue. 20 years later the problem is back but not as severe.
300zx nissans I used to work on at the dealer were notorious for this. That procedure came from a TSB that was sent out. I know a 300zx is far from a pagoda but the same principals apply.

[jorge espinoza]

I have the same issue of grinding when shifting into reverse from neutral and sometimes a clunking sound when going from neutral to first, which I can never replicate when my car is being serviced. I now shift to first gear then neutral and no grinding when going into reverse .The car drives very smooth and no grinding other than when shifting to reverse . I'm going to speak to my tech to see if this is my issue also .

[Tyler S]

Jorged, try Depressing the clutch for a few or so seconds before shifting to reverse. This gives the input shaft time to stop spnning. If the pilot bushing is ok there should be no grinding.

[mgpcpa]

Tyler, thanks for the reply. BTW, what is the range of acceptable free play in the clutch? Also, I'm not clear on that 2nd test for the pilot bearing. Start in neutral, clutch in & shift to 1st, 1st back to neutral, wait 10 seconds in neutral with clutch still in, then shift neutral to reverse. If it grinds, then a bad pilot bearing. Is this what you meant? Please advise and thanks again. Hopefully it's a pilot bearing problem (and maybe a new clutch too--same one in the car since I bought it in '98) and I won't need a total trans rebuild.

[Tyler S]

Yes, you have the procedure right. What will happen if the pilot bushing is hanging up is the input shaft will again start spinning. Since the clutch is in and the shaft was initially stopped by having it in first gear it should not.
Try blipping the throttle when downshifting and see if it helps.

[ja17]

I always replace the pilot bearing automatically, it is very inexpensive. However, I have never run into a bad one ?! I find that most shift problems on these transmissions are caused by worn or broken gear cluster keys and loose slotted flange nuts. Main bearings can be bad also.

[mgpcpa]

Joe: You mentioned that a pilot bearing for my '71 280 SL manual trans is inexpensive. Could you give me an approx. figure? Thanks

[ja17]

The part is usually less than $20.00.

[mgpcpa]

Joe:
      I need to replace the pilot bearing in my '71 280SL, any my independent tech suggests that I may as well replace the clutch, too. I got some prices from the dealer, and the total cost of clutch disc, plate, release bearing and pilot bearing comes to almost $1000! Pilot bearing alone is $70, when I see it elsewhere as low as $8. Please recommend a couple companies that you trust that sell quality parts at a reasonable price. Thanks!