Synchro Replacement, 1st Gear Options

[Chaznaster]

Hi.

I am planning to address the grinding I get when going into 1st gear at anything faster than a full stop. The Pelican article on the replacing first gear seems pretty good, and I plan to search these pages for nuggets of wisdom before starting.

This thing has been grinding as long as I have had it and certainly long before that ... so I figure it is in pretty bad shape.

Pelican suggests the following parts: slider, shift fork, synchro ring and brake band, dog teeth, and maybe first gear if it is worn. I plan to open it up before getting parts - and I assume they are all available without much trouble.

I'd appreciate your thoughts on tackling this project as well as any advice.

Thanks. Christian

[mgphoto]

Hi.

I am planning to address the grinding I get when going into 1st gear at anything faster than a full stop. The Pelican article on the replacing first gear seems pretty good, and I plan to search these pages for nuggets of wisdom before starting.

This thing has been grinding as long as I have had it and certainly long before that ... so I figure it is in pretty bad shape.

Pelican suggests the following parts: slider, shift fork, synchro ring and brake band, dog teeth, and maybe first gear if it is worn. I plan to open it up before getting parts - and I assume they are all available without much trouble.

I'd appreciate your thoughts on tackling this project as well as any advice.

Thanks. Christian

You do know there isn’t any syncro from 2nd to first, you basically have to let the gears mesh up to shift.

[rfinegan]

Dr Evil may have some of the parts both new or used...
Ill look for links of the you tubes I recorded when I updated mine

-Robert

[mepstein]

My experience, after rebuilding a couple dozen transmissions over the past couple years is it’s rarely just first gear. That gear might be giving you most of the issues but unless it’s a really low mileage trans, there’s probably more to do. You will know once you open it up.
Before you get too far into it, you can open up the side cover and inspect the ring and pinion. A damaged r&p pretty much disqualifies the trans from getting rebuilt.

[Dave_Darling]

You do know there isn’t any syncro from 2nd to first, you basically have to let the gears mesh up to shift.

That is incorrect, there is a synchro on 1st gear. In stock form, it's a different one from the others, but any of the other synchros can be used as long as you use the other parts (e.g., the stop blocks and maybe other stuff) that go with them.

A number of old cars do not have synchros on first gear. AFAIK, all Porsches have always had 1st gear synchros. (Possibly some very early 356es did not, but the later ones did!)

--DD

[brant]

You do know there isn’t any syncro from 2nd to first, you basically have to let the gears mesh up to shift.

That is incorrect, there is a synchro on 1st gear. In stock form, it's a different one from the others, but any of the other synchros can be used as long as you use the other parts (e.g., the stop blocks and maybe other stuff) that go with them.

A number of old cars do not have synchros on first gear. AFAIK, all Porsches have always had 1st gear synchros. (Possibly some very early 356es did not, but the later ones did!)

--DD

(IMG:style_emoticons/default/agree.gif)

[914werke]

Hi. I am planning to address the grinding I get when going into 1st gear at anything faster than a full stop. The Pelican article on the replacing first gear seems pretty good, and I plan to search these pages for nuggets of wisdom before starting.
Pelican suggests the following parts: slider, shift fork, synchro ring and brake band, dog teeth, and maybe first gear if it is worn. I plan to open it up before getting parts - and I assume they are all available without much trouble.

I'd appreciate your thoughts on tackling this project as well as any advice.

Thanks. Christian

1st can be done in the car, easiest id you have a lift but do-able on stands.
You'll definitely need a slider, the 1st/reverse syncro (which is spendy) & dog teeth.
Doubtful you'll need a fork or brake bands/block.
As others mention the 1st revers syncro is usually perished if it hant been touched in 50 yrs but normally 2nd is also pretty hammered which means pulling the stack. (IMG:style_emoticons/default/confused24.gif)

[Ninja]

Dr Evil may have some of the parts both new or used...
Ill look for links of the you tubes I recorded when I updated mine

-Robert

No one has said it yet...

The EVIL Doctor is the BOMB regarding these transmissions!

I would get/search EVERYTHING he has posted.

To me (I'm experienced) his info is the GOLD standard even beyond Porsche themselves.

Hit up the Dr early instead of late. He is one of those special guys you gained access to by joining the forum.


(IMG:style_emoticons/default/ninja.gif)

[ctc911ctc]

You do know there isn’t any syncro from 2nd to first, you basically have to let the gears mesh up to shift.

That is incorrect, there is a synchro on 1st gear. In stock form, it's a different one from the others, but any of the other synchros can be used as long as you use the other parts (e.g., the stop blocks and maybe other stuff) that go with them.

A number of old cars do not have synchros on first gear. AFAIK, all Porsches have always had 1st gear synchros. (Possibly some very early 356es did not, but the later ones did!)

--DD

(IMG:style_emoticons/default/agree.gif)

[mgphoto]

Has anyone on this board ever down shifted from 3000 rpm in second gear to first, and had their tranny survive. No need to try.

[mgphoto]

Please observe parts 41, 8 and 9. Syncro only on one side, up shift only.


Just saying.

[ctc911ctc]

You may find this helpful: http://www.914world.com/bbs2/index.php?sho...=376106&hl=


I have done 3 of these

One with 20K miles
1st gear - replaced dog teeth and Sync Ring
2nd gear - replaced dog teeth, Sync Ring AND swapped 4/5 selector with the 2/3
One with 90K miles
1st gear - replaced dog teeth and Sync Ring
1st gear - replaced the 1/R Selector -
2nd gear - replaced dog teeth, Sync Ring
2nd/3rd - replaced Selector - it was too far gone to move to 4/5
One with ? miles that was from a 1970 burn-down in 1984
just replaced the sync rings in 1st and 2nd and a dog teeth in 2nd

Dr. Evil's videos are a MUST - unless you were factory trained or similar 901/915 tranny work, start with the videos.....all of the tricks are in them

ALSO - VERY IMPORTANT (IMG:style_emoticons/default/blink.gif)

The linkage - setup, bushings, wear need to be addressed - short money and will tear the transmission apart if not addressed - every-time you go in, replace all of the bushings.

I have never replaced a gear. All of them were perfect.

The beauty of the design is that the gears are always protected by the dog teeth - it takes a great deal of abuse to grind the dogs to the point that the gears are not turning in sync. What you are hearing is the dog teeth protecting the gears. This happens because the sync rings are warn-out.

Happiness is the first time downshifting to first while rolling and there is no noise......Ahhhhhhhhh

[ctc911ctc]

The difference in gear-spin is pretty severe at that end of the gear train, when everything is new, and you do it slowly (3 Mississippi's) it should work, however, the sync rings will suffer.

Has anyone on this board ever down shifted from 3000 rpm in second gear to first, and had their tranny survive. No need to try.

[brant]

Has anyone on this board ever down shifted from 3000 rpm in second gear to first, and had their tranny survive. No need to try.

sure have had missed shifts on the track

usually zings a valve on a six

but tranny survives

our race box (always new sliders and in great condition)
can easily down shift in anger and does so frequently...
increased wear that is addressed when needed to maintain performance


F, J, O, S, V (904 mainshaft)
tilton twin disc 5.5 inch clutch
flywheel in the range of 4-5lbs
TB LSD
billet intermediate and cooling
no reverse gear (try to fit " F" into first and youll see why)

[Jack Standz]

Please observe parts 41, 8 and 9. Syncro only on one side, up shift only.


Just saying.

Actually, those are the brake bands and stops/anchor block/thrust block. The "syncros" (synchronizer rings) are actually #10.

And yes, only one brake band on first gear (although, IIRC you can use parts from gears 2-5 to run two brake bands on first gear if you want to for some reason).

[ctc911ctc]

43 is $$$$$

Dr. Evil sold me one that was really good - I bought a core to raid for parts and it was the cleanest transmission of all of the ones I have!!!! Sometimes you get lucky.

Please observe parts 41, 8 and 9. Syncro only on one side, up shift only.


Just saying.

Actually, those are the brake bands and stops/anchor block/thrust block. The "syncros" (synchronizer rings) are actually #10.

And yes, only one brake band on first gear.

[dr914@autoatlanta.com]

easily done with the transmission in the car, just remove the muffler and the rear cover. We have sold many many first gear repair kits over the years and the kit comes with instructions, easily done in less than two hours

Hi.

I am planning to address the grinding I get when going into 1st gear at anything faster than a full stop. The Pelican article on the replacing first gear seems pretty good, and I plan to search these pages for nuggets of wisdom before starting.

This thing has been grinding as long as I have had it and certainly long before that ... so I figure it is in pretty bad shape.

Pelican suggests the following parts: slider, shift fork, synchro ring and brake band, dog teeth, and maybe first gear if it is worn. I plan to open it up before getting parts - and I assume they are all available without much trouble.

I'd appreciate your thoughts on tackling this project as well as any advice.

Thanks. Christian