IcemanG17

Okay my 1979 Racer has serious transmission problems....other than the nut behind the wheel who can't shift....

The trans was balky at best when I got it....changed the short shifter to the stock long shifter for more leverage and better feel...that improved things....then I bled the clutch per WSM and that also made things better...

When the trans is cold, iot shifts fine...the standard intermediate plate test of "does it grind 1st or reverse" is no problem..... BUT once its hot....its a MESS.....it grinds every gear and often locks up entirely...... You can hear it and feel it....the shift lever gets tense and doesn't want to do anything....but the car is NOT in gear....you pump the clutch endless while trying to rev match....but its nada-nothing....whats even more weird is it the worst during UPSHIFTS.....

It always crunches a bit during downshifts, unless the rev match is perfect....

I am leaning towards a worn intermediate plate that gets horribly out of adjustment......

Watch the video and you can see & hear the issues.....

I need HELP.....while Casper is quite fast as a 1 speed...it sucks....

brutus

What you running for gear lube ??

hacker-pschorr

Any trans coolers?

Mike Simard

That stuck shifting at 2:50 brings back memories. My early box would get stuck in 3-4 if shifted aggresivly and as far as I could tell it was just possible for the shift forks to have both gears engaged momentarily under those conditions. That tendancy seems to not be there in later boxes but I'm not sure.

That one could be unrelated to the other generally crunchiness. That could be heat boiling old fluid and you may not cure that with a basic bleed. Maybe you justy need a new master too, I'd suspect the hydraulic system though.

If you replace the master and slave, fill with good fluid and start being very gentle shifting 3-4, I bet Casper will be a new car.

justaguy

Brian
That sucks. I feel your pain the 52 does the same thing only worse.

IcemanG17

gear oil is amsoil severe gear 75-90, no trans cooler of any type...we changed the gear oil when I got the car so it is fresh...the LSD does slip quite a bit, so that will contribute to extra heat in the box....

when I bled the clutch there was some air bubbles, but now it is fresh Super Gold....should be plenty good....and there are no apparent leaks either....pedal feel is good and stays consistent while driving...however the engagement point changes quite a bit....when cold its right in the middle....the hotter it gets the lower to the floor it gets....

Imo000

I sort of remember reading something about early transmission locking up during race conditions and it was caused by the heat and expansion of the case that caused it.

Rob Edwards

At some point Anderson told me that he saw 300o oil temps in his (non-GTS) transmission, before he added an external cooler. Not sure which iteration of which car this was in. And he also mentioned that one cooler is not enough for the GTS box in the current car, he's got two.

IcemanG17

I also have heard two coolers or one large one are required.....

A large contributor to the heat is the LSD...think about it.....each time it works its generating serious heat......on top of whatever the gears create.....oil is the only cooling medium....

I think a properly cooled trans is in my future....just need to find the $$$$

SeanR

Brian, from the 3 minute mark on, your shifter looked like it was aligned for crap. Are you sure that thing is as tight as it can be? Car sounds great and the driving is superb.

IcemanG17

Sean
The shifter is slightly angled towards the driver...on purpose.... The feel of the shifter is okay at best...I am guessing the forward shifter cup is old...the rear coupler looks okay, but the rubber bushing are old and hard...with a couple small cracks....

Thanks about the driving I also agree with the sound...it just RIPS....it sounds like I am turning crazy RPM, but I shift at 6k....

16V 928's with headers and single 3.5" systems tend to sound pretty good!!!

WallyP

"...pedal feel is good and stays consistent while driving...however the engagement point changes quite a bit....when cold its right in the middle....the hotter it gets the lower to the floor it gets..."

That's where I would start. They don't shift well when the clutch doesn't release.

Dave928S

I had exactly those issues on my 82 when the intermediate plate was 'adjusting itself' .... jamming in gear and not able to get it out of gear which was worse as it got hotter. Removed the rivets and put bolts in to lock it in the correct adjustment fixed that, and the reverse/first crunches as well.

Podguy

One place you might look at is the crimped clutch hose. I had similar problems with the engagement point changing on my 78. All the bleeding in the world would not cure the problem. Turned out the hose was leaking air. It was porous enough to take in air but not enough to leak fluid.

I also had good luck with 928 Motor Sports shift coupler. The plastic coupler gets hot and can even melt. You may have some changes in the shift position that is causing problems as things get hot.

Podguy

Do you have any pictures of the modification. What sized bolts did you use and in what direction.