C4inLA

Gents, i have a real puzzle and truely welcome any suggestions that i might try to narrow down the issue to the drivetrain component if possible before I take to Indy or dealership..

Background

94 C4 WB gets a couple thousand miles a year, currently, 44k miles. Street, Stock setup and drive it like a buick, so sad.. I want to turn loose the horses Only problem ever had, DMF went knock knock knock going 30 mph on Sunday drive to breakfast at 30k miles on clock several years ago. Replaced with same and new clutch same time. All good since.

So, new problem!

Symptoms;

Out of level driveway from stop, sharp turn, kind of a bind/bang(like a spring torques and let's go)/grind for 2 seconds, gone....? In reverse, going in garage, sharp slow turn, same thing. If straight line in 30ft driveway, forward and reverse, seems normal, So, I thought ... See below.

What I have eliminated;

Brakes/Calipers.

Suspension-Steering rack, springs, dampers, swaybars, links. Not suspension.

CV joints-Having researched CV joint failure on sharp turns I serviced all CV's.

As car will not be driven until resolved, I've deferred this issue for months and been having fun with lots of other maintenance.

Did a 13pt bleed weeks ago, no change. To be clear, all maint done or being done is after this issue manifested.

Changed gear oil front/back yesterday and all is well. Magnets were very clean, very few shavings.

I have been trying to find info on shift linkage adjustment in workshop manuals and can't find it looked in manual transmission section and chassis section?

Well, today more driveway testing, in straight line, from stop tried quick 1st gear start and got a growl grind, not the bang. I thought it was just sharp turns, now I have a new piece to puzzle.

Please talk me off the edge!

All noises and symptoms can be replicated. Noises last for a second or two.

Tomorrow I might just strap my video camera to a few spots on the underside and see if I can narrow sound and location.... I'm Buggered for now

Meanwhile, have bumper covers off and ready for respray soon.

peterC2S

Sounds a lot like this...

https://rennlist.com/forums/964-foru...nightmare.html

If so, bad luck. There are some earlier posts referenced within the thread plus an explanation and pics as to what happens when the pins in the planetary gear set work loose.

C4inLA

Symptoms kind of fit ... Welcome to the big leagues . Not the news I wanted, but gives me a direction to pursue... Thanks for the feedback. It's back to "purdy" Garage Queen and Car Cover I was so hoping a thing like this wouldn't develope until I clocked 200k miles....

So, I read the threads looking to solve the issue outside dealership, is this cost or material availability or PNA not servicing this issue?

peterC2S

Given where you are you may be able to mitigate the cost if you can find the right C4 being broken down for parts. The planetary gearset is the big cost - then you need to get the pins welded so lightning doesn't strike twice

No way of avoiding the labour cost - it's an engine drop job. And then of course you might as well do other stuff while its out...

C4inLA

34-2 (18) in workshop manual, looking and reading right now....

Is the theory that a floating pin is sinking to bottom and catching on a gear in slow sharp turns, but straight driving is somehow avoiding the gears? Maybe the turning motion is throwing pins to the trajectory of 1 of the 3 gears... Wild stuff ...

peterC2S

Given the noise you describe I'd suggest the damage is already done. A pin working loose is the first bit but once it's loose it's more likely that you have a bit of gear floating around in there. Either way you'll need to get into the planetary unit to see how bad - if your mechanic confirms that is indeed the source of the noise.

C4inLA

Agree.

John McM

Planetary gear issues are not rare, but not common either. My car had a cracked gear that was able to be saved. A fellow Rennlister had his go completely. Hope your diagnosis is different. If not, then it's fixable, just costly.

C4inLA

I suspect I have joined an elite club I will keep all updated. Until i feel comfortable sourcing carrier, don't want to open things up. My baby will get few starts a week and a permanent link to the trickle charger Meanwhile, RL community will continue to inspire me ......

Cheers!

Feudal Serf

I went through the planetary gear problem last year.
Car was fine then one day it wasn't. No real warning.

Here is a post I did with some links to pics.

I sourced a used planetary gear set and some other bits required from metal bouncing around.

https://www.dropbox.com/s/60yqh3dygp...G_00000171.jpg

https://www.dropbox.com/s/b08im7xg6r...G_00000171.jpg


Car was stuck in 2nd gear.

Gearbox has to come out in order to take the nose off and inspect. I did a new clutch as well.

Cheers and good luck

Chris


FSG_00000169.jpg
Found someone with an old C4 gearbox.

Car was stuck in 2nd gear.

FS