First start, need at least one minute warm-up before shifting into reverse?
 

First start of the day, before pulling out of the driveway. I seem to need at least one minute for the car to warm-up before shifting into reverse to avoid a grind like noise. This ONLY occurs on the first start of the day. What's happening here? Reverse shifitng no problem the rest of the day. Is there some "equality" necessary in engine RPMs and reverse when first running the car for the day?

Wierd.

Have you tried running through the gears before "reverse?" I have had something like this happen a few times but I usually back in the garage now so I hardly use reverse in the mornings.

I still cannot figure this only happening on the very first reverse shift of the day, then the rest of the reverse shifts all day are smooth. ????

I have the same problem. I think mine is because I need to rebuild my tranny; possibly, I also need to replace my clutch.

p.s.,

I once adjusted my clutch and it went away. I adjusted the clutch again, shifting was better....at the expense of the morning 'grrrrriiiinnnnndddddinnnng.'

Its grinding because there is no synchro on reverse. Push the clutch in, count to 5 to let the input shaft of the transmission spin down, and then shift into reverse. If the input shaft isn't spinning, it won't grind.

what I usually do is start with the clutch out, push the clutch in, shift into first, and then shift into reverse, and then ease out the clutch and back up. No grind here.

If I go straight to reverse, I'll get the grind.

One step of a PPI is to see how long it takes for the clutch to wind down in order to get a car in reverse. Warped clutch and/or cold oil will both cause an undue amount of time before reverse can be engaged without grinding.

I push in my clutch, wait up to five seconds or more, then gently put the car in reverse. This is a car with a fresh clutch and 915 rebuild. You can never be too careful...

John

I concur.

Did you do the rebuild John?

put it in second gear 1st, then keeping the clutch depressed run it right to reverse.

Paul:

No, JohnW did the work. I just moved to the Swepco fill after John's oil fill of (I think it is?) Kendall. Frankly I don't notice much difference, but overall it is a thing of beauty now compared to its prior state.

John

Ok, so if I understand this correctly, there is no synchro on reverse (i.e. it's not a part of the Porsche 901 transmisssion for reverse?). I have a very new clutch, so I'll try using the "wait and spin down" method suggested here. Thanks.

Correct, and I don't believe the 915 has synchro reverse either unless it came along towards the end.

Clutch has nothing to do with this one... just start it up, push the clutch in, shift to first, and then immediately shift to reverse.

The clutch doesn't come into play at all in this case. Now if your first gear synchros were shot...