Transmission Troubleshooting

[Nacho]

Ok next one on the car restoration project........have connected up the driveshafts and are locked in nicely to the tip........however when I turn the wheel hub manually, they still turn in Park with a grinding sound. I'm confident I've connected the gear selector in the right place.

Have turned the hubs/wheels on both driver and passenger side and same noise/result. Feels like something's slipping or not connected right. There's no oil in the tip box yet. Does that make a difference?

Thoughts?

[Bennoz]

Brake rotors?

[Nacho]

Grinding noise is coming from where both the driveshafts connect. It turns pretty easily without a lot of force. It's like the driveshafts are connected but what they're connected to isn't.

If it helps this tip tranny I got off someone who did a manual conversion. Do you know if there's some components you use from the old tip and use in the manual after conversion?

[Bennoz]

When you slid the shafts in, did you give them a good whack on the ends with a lump hammer? So the circlips on the ends of the shafts snap into place inside the box?

[Nacho]

Ok pulled shafts out and back in and hammered it this time but still the same result.

I've got an old busted tranny in the garage which may help explain better. When you insert the shafts on the busted tranny and turn while it's in park, it remains locked and doesn't turn as it's supposed to. Then move the gear selector to Reverse and turn it there's a good amount of pressure/resistance and will let you turn the shafts in reverse.

On the one connected to the car it still turns even in park or in any gear almost like it's slipping and gear's not engaged and it's fairly easy to turn as if there's no pressure/resistance there. I'm hoping this diagnosis doesn't require ripping the b*stard out again. Any other thoughts?

[PHIL069]

There's no oil in the tip box yet.

Is there oil in the old busted one in the garage?

[Nacho]

Hey Phil. Unless Dwayne drained it, I haven't so I'm assuming yes. I've topped up the new tranny with oil but still the same.

[Bennoz]

Clearly it's time for a Bennoz limited edition manual conversion kit

[payaya]

Sure the spline count matches up?

[Bennoz]

Valid point!

[silverGPX]

When you slid the shafts in, did you give them a good whack on the ends with a lump hammer? So the circlips on the ends of the shafts snap into place inside the box?

I did not do this, should it be okay if it still drove fine after I put it back together?

[Nacho]

And the plot thickens.......

Ok I think I might have worked it out but need you experts. With dumb luck I pulled the driver side shaft and left the other one in and the noise went away. Pulled both shafts and found a couple of weird things:

1) There's a metal bar running through the middle of the connected tranny.......but not on the other one........why?






2) I knew the shafts are already varying number of teeth and lengths but seriously why are some heaps longer......I think the connected tranny came from Max's (mxysxy) old FTO which is GPX. Which driveshaft should it be? Is the GPX shaft diameter greater or smaller than a GR shaft diameter?

In the pics the leftmost shafts are driver side shafts. The three on the right are passenger side shafts. Why do they all seem to be slightly different lengths?







So best advice on which ends should go into a GPX tranny. And wtf is that metal bar? That metal bar could be the cause of the noise or preventing the driver's side shaft from locking into place.

[Bennoz]

Ahhhhhhh.......

First tip pictured is standard. The shaft through the centre is the standard diff pin.

The second tip pictured has an LSD. Judging by the stubby & longer driveshafts you have there, it's an early style viscous LSD box.

The shafts you should be using in the box with the standard diff (with pin) are the ones in the middle so long as they are the correct spline count. The standard shafts for a standard box have a 28mm shank length (measured from the base of the splines to the mating face of the joint) and both the drivers side & passenger side are the same length. That long & short ones you have on the far right & left of the picture belong to the LSD box.

You can't pin point what diametre shaft to use based on the model (ie GPX) they used a mismash of them in all different models. The only sure way to know is to either throw some verniers around the hole in the diff / the driveshaft, or count the splines.

The 2 size driveshafts are 25 splines (26.6mm shaft dia) & 27 spline (28.5mm shaft dia.)

[Sahin]

"When you slid your shaft in"

[payaya]

Valid point!

I've seen this too often. 25 spline shaft instead of 26 and the funny thing is the shaft will go into the gearbox fine and feels like it fits. Turn the car on and as soon as you put any force on the shaft it grinds and you have no drive.

You need to manually count the splines, even if you have varying lengths it shouldn't grind.

Pull the shaft out, if it's grinding in its housing you will see this on the surface of the splines.

[Nacho]

I've pulled both shafts out and decided to test just moving across the gear selector.

What I've found is that when moving the selector (eg. Park to Reverse, etc.) I get a loud electrical buzz and slight grinding noise even when shafts aren't connected

Ever heard this one before?

[Bennoz]

I've pulled both shafts out and decided to test just moving across the gear selector.

What I've found is that when moving the selector (eg. Park to Reverse, etc.) I get a loud electrical buzz and slight grinding noise even when shafts aren't connected

Ever heard this one before?

Clearly it's time for a Bennoz limited edition manual conversion kit

[payaya]

I've pulled both shafts out and decided to test just moving across the gear selector.

What I've found is that when moving the selector (eg. Park to Reverse, etc.) I get a loud electrical buzz and slight grinding noise even when shafts aren't connected

Ever heard this one before?

Buzz is normal. So its a gear box you put in? Flexi plate bolts tight?

[Nacho]

I'll have to listen out for that buzz on my other FTO to see if I can hear that 1 second electrical buzz. Can't say I've heard it before.

Ok tranny is almost sorted. Shaft end have been swapped around and they're perfectly locked in, no more grinding noise and they both turn together when you manually turn the hubs.

Only problem now is that when I put it in gear (R or D) only the passenger side turns. Not sure if that's normal.....surely not?

[Nacho]

Ok the box is possessed. Finished doing the brakes and decided to test. Still having the issue where Reverse and Drive only the passenger side is turning but when I went to test the brake.......when you hold the brake pedal about halfway down all of a sudden the driver side hub/shaft starts to turn.....WTF?