Grinding when downshifting into first

[cabmandone]

My 85 Carrera has a shift problem. When I downshift from 2nd to 1st it will grind unless I'm at or near a complete stop. When going up through the gears 1-2 etc the car shifts good as long as I take my time from 1-2 (normal from what I have found) but every other gear shifts flawlessly.

Am I looking at syncros or can this be a clutch cable adjustment or shift coupler problem?

[dyount]

I'd say normal and no reason to downshift until you are all but stopped

[yanik]

agreed.... you should never have to downshift into first when rolling... that gear is only designed to get you moving...

[Jdub]

It cannot hurt to look at replacing the bushings in your shift assembly and adjust the coupler, plus check your adjustment of the clutch cable.

Shift into first only when gliding into a stop or already at a full stop, and only if it falls into gear - never push this or you will be very sorry indeed!

[cabmandone]

Thanks for all the replies.
My problem is, we have some rough R/R crossings and I slow down to a point where first would be nice to have. I can't get into first at 5mph. That doesn't seem right. At 5mph, 2nd is too low and I'm lugging the engine.

[kodioneill]

You should be able to downshift into 1st at a slow speed. The syncro bands , slider and dog teeth are most likely worn. Be ready to spend some cash because they're not cheap.

[yanik]

Also something to thinking about is making sure your clutch is fully engaged and the peddle is to the floor.

[porwolf]

Double clutch when you downshift to 1st while rolling. If done properly it should be easy. I learned driving on a VW that had no 1st gear synchronisation and I was able to get it pretty easily.

[nickyclyde]

I have a good transmission ,always double clutch to keep it that way.

[porwolf]

Originally Posted by nickyclyde

I have a good transmission ,always double clutch to keep it that way.

Agree. I always double clutch when the RPM's are middle to high. It really also makes a difference when going down from 3rd to 2nd on the twisties. Down shifting then is very smooth. And, of course, double clutching saves the synchronisation.

[Charles Freeborn]

First gear synchro is going or gone. Double clutch or replace....
-C

[boyt911sc]

Originally Posted by kodioneill

You should be able to downshift into 1st at a slow speed. The syncro bands , slider and dog teeth are most likely worn. Be ready to spend some cash because they're not cheap.

Agree. Since after the transmission rebuilt, I could down shift to 1st at slow speed easily. Before, I had to wait till the car almost come to a stop and go to 1st gear.

Tony

[Bob Kontak]

Originally Posted by boyt911sc

Agree. Since after the transmission rebuilt, I could down shift to 1st at slow speed easily. Before, I had to wait till the car almost come to a stop and go to 1st gear.

Tony

+1. Same with my 81. Never knew you could shift into first while moving before rebuild.

Go over the tracks at ten mph. The chassis can handle it.

[cabmandone]

Originally Posted by Bob Kontak

+1. Same with my 81. Never knew you could shift into first while moving before rebuild.

Go over the tracks at ten mph. The chassis can handle it.

My chassis might handle it but nothing on the bottom side will be able to. My car is pretty low.

Thanks for all the replies. It sounds like some syncros could be in order.

[wacko]

I had the same problem on my 82. Synchro was shot. You should be able to shift into first without being stopped. You can live with it but it is not the way it is supposed to be.

[PaleoMan]

Old thread, but still useful. My 356 easily downshifts to first while moving, but my 79 911 grinds like crazy going into first while moving even pretty slow. It's hard to remember not to downshift in the 911. Is replacing syncros something a rookie mechanic like me can do, or need a pro? Anybody have a link to a procedure? thx!

[917_Langheck]

Originally Posted by PaleoMan

Is replacing syncros something a rookie mechanic like me can do, or need a pro? Anybody have a link to a procedure? thx!

Really good series of videos on the 915 rebuild here:

https://youtube.com/playlist?list=PLkWFofpgz2Ogxk1t7bR-NrnlO7AGU-vbE

[pampadori]

Originally Posted by PaleoMan

Is replacing syncros something a rookie mechanic like me can do, or need a pro? Anybody have a link to a procedure? thx!

I would rate this a 4 wrench job on a 5 wrench scale of difficulty.

These cars were builty by humans and you sir are too a human. So you can do it. However, this is a very difficult repair. You will need to remove the engine and transmission from the car and fully tear down the transmission. You'll need tons of tools and equipment to do this one.

I think i'd suggest paying a pro to handle this one.

[Bill Douglas]

There must be something wrong with my transmission.

In the '79SC I can shift down from 2nd to 1st, or even from 3rd to 1st any time I want.

The corner into gun club road is effectively a hairpin at the bottom of a winding downhill run. I find it easier to pile on the brakes and do a 3rd to 1st for some reason. I've done it for years without it being a problem.

[David Inc.]

Originally Posted by pampadori

I would rate this a 4 wrench job on a 5 wrench scale of difficulty.

These cars were builty by humans and you sir are too a human. So you can do it. However, this is a very difficult repair. You will need to remove the engine and transmission from the car and fully tear down the transmission. You'll need tons of tools and equipment to do this one.

I think i'd suggest paying a pro to handle this one.

Just synchros? Yeah maybe 4/5. Inspecting and replacing everything that you'll have access to with it apart? Full 5/5.