zf shifting

I am new tot he zf box, but.
My car will not downshift to second from 4th, it has to go through third, even if i double decluctch in neutral.

It also refuses to engage reverse unless it has rolled forwards a foot or so in 1st, even then engaing rverese has a gear clunk. reving in neutral with clucth out and then enaging is no help.

Is this normal?
 
In a word -Yes- with regard to the forward gears, the shifter mechanism internally is apparently designed to favour a sequential type shift pattern rather than dropping from fourth to second like you would prefer. First has synchro, while reverse has a sliding gear (crash) to engage.
 
Thanks, that is a relief, i was worried. I guess 5-4 is a natural.

So if I wnat to go 5-3 I need to got through 4 also?

A sequential shifter would be better then.
 
Thanks, that is a relief, i was worried. I guess 5-4 is a natural.

So if I wnat to go 5-3 I need to got through 4 also?/QUOTE]

Well, you tell us! We're not there to see how your car is reacting to your inputs.

If you have an original GT40 (or, an original GT40 gearbox at least), those had a built-in sequential shifting mechanism, which would not allow the driver to skip gears. If you are in 4th gear, it will only allow you to select 5th, or 3rd. If you're in 5th gear, it will only allow 4th, and so forth.

But of the many thousands of ZF gearboxes built, only a handful were built that way (probably less than 150). So, the overwhelming majority will allow you to shift from any gear, to any gear.

Can you shift any way you like when the engine is shut off? If so, then you do not have a sequential-type shifter. In that case, your problem is probably tied to inadequate clutch disengagement and/or worn-out synchros.

Tell us what kind of ZF you have? And try shifting gears with the engine shut off and tell us if it works? If your problem only exists when the engine is running, you have to adjust your clutch for additional release, or your gearbox synchros are worn to the point where it could likely use an overhaul.

Let us know?

Also, FWIW, due to the non-synchro nature of reverse gear, I find it useful to shift into a forward gear (normally I use 2nd gear) before shifting into reverse, when the engine is running, to avoid the CRUNCH you are describing....
 
Mike

It seems to go down through the other gears fine, although I dont think I went 5-3.
Thanks for the feedback. The reverse part I get, will try second.
Yes I can shift into gears while stationary.
The gearbox is a new, RBT 100 miles on it.
Either the clutch was not disengaging properly, although the other gears were fine. Or the there is a problem with the second gear syncro on downshifts. Because there is no way, whether I double decluch etc thtat it will go int second even at a slow speed from 4th, it has to got through 3rd and the secon comes with a a graunch.

Will check the master and clutch disengagement, hopefully that solves the issue, although curious it was only comming down to second, otehrwise I guess its a bad syncro

Dont want to think of the hassle and expense of pulling the motor box and getting the new tranny redone..
 
Is there a different synchro for going up the gears to down, because it shifted up from 1=2 just fine.
 
If it's a new gearbox, and it has oil in it (don't laugh--more than one RBT customer destroyed his new or newly rebuilt gearbox by installing it in the car and forgetting to put oil in it before driving it!), then the problem is improper adjustment of the clutch, giving inadequate release (or, less likely, a linkage problem). The gearbox is just an innocent victim.

Do you have a cable shifter? Those things are quite finicky and not nearly as effective as a quality rod shifter, as per the originals.
 
Sean,

I have the same setup as you with RHD and the RBT. Dennis also did my install and I'm afraid I wont be any help, mine shifts great. I can go from any gear to any gear and reverse just slides in. I thought this was due to the RHD and the rods instead of the LHD with the cable and pulley's. I'm thinking it is something other than the transaxle, clutch, adj. of the shifting rods, etc... Good Luck!

Mike
 
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