Gearbox/Propshaft yolk

[Gorpon73]

Hello Gents,

Troubling question regarding the splined yolk on the gearbox end of the prop shaft.

I've removed/installed the propshaft a couple times using the "detach at diff flange, pull rearward / remove shaft pulling forward through tunnel after lifting gearbox" method. Previous time doing this I've been able to re-attached the splined yolk on the onto the shaft on the gearbox end.

For some reason, I can't seem to slide it back on this time. It will slide on an inch or so and I can tell the splines are lined up because when in gear, it won't rotate and when out of gear, it will turn.

I'm stumped why it won't slide on this time. It seems like it will not slide onto the shaft past the actual gearbox housing. Totally stumped. Any suggestions?

[billwill]

Bits of broken splines caught up in the spline grooves?

Poke a phone-camera in through the hole in the side of the tunnel and take a movie of the back end of the gearbox to see if you can see any obstruction, maybe.

[promotor]

Hello Gents,

Troubling question regarding the splined yolk on the gearbox end of the prop shaft.

I've removed/installed the propshaft a couple times using the "detach at diff flange, pull rearward / remove shaft pulling forward through tunnel after lifting gearbox" method. Previous time doing this I've been able to re-attached the splined yolk on the onto the shaft on the gearbox end.

For some reason, I can't seem to slide it back on this time. It will slide on an inch or so and I can tell the splines are lined up because when in gear, it won't rotate and when out of gear, it will turn.

I'm stumped why it won't slide on this time. It seems like it will not slide onto the shaft past the actual gearbox housing. Totally stumped. Any suggestions?

Has the gearbox been to pieces recently? Sounds like it could be a misalignment of the mainshaft - is the mainshaft sitting centrally in the tailcasing when viewed from the end? Either that or theres something inside the propshaft nose that's stopping it going in?

[Gorpon73]

Thanks for the suggestions.

Funny, I did try to take a picture with my phone from the diff end. I'm aligning the splines up through the front of the frame opening. Was hoping to avoid messing with the interior to get through the side tunnel port, but may have to.

The gearbox has not been apart. Strictly a remove, balance and re-insert.

Super annoying. This used to be a relatively straightforward chore...

[promotor]

Thanks for the suggestions.

Funny, I did try to take a picture with my phone from the diff end. I'm aligning the splines up through the front of the frame opening. Was hoping to avoid messing with the interior to get through the side tunnel port, but may have to.

The gearbox has not been apart. Strictly a remove, balance and re-insert.

Super annoying. This used to be a relatively straightforward chore...

Ok, sounds like the problem is with the prop then if all else hasn't been messed with. Have you had a look inside the prop nose to see if there's any damage etc? The splines are the same as diff output shaft splines so if you've got one of those handy you could see how well one of those goes into the prop nose?

[nmauduit]

Bits of broken splines caught up in the spline grooves?

or probing with a magnet_on_a_stick in case something has found its way where it should not ?

[alan.barker]

Thanks for the suggestions.

Funny, I did try to take a picture with my phone from the diff end. I'm aligning the splines up through the front of the frame opening. Was hoping to avoid messing with the interior to get through the side tunnel port, but may have to.

The gearbox has not been apart. Strictly a remove, balance and re-insert.

Super annoying. This used to be a relatively straightforward chore...

The correct way is remove drivers seat to access through Tunnel side port.
Alan

[Gorpon73]

Thanks for the suggestions.

Yes, the splines look clean. No nicks or burrs.

@Alan, thanks. Yes, it looks like I'll be going through the port in the tunnel from the inside of the cabin now. The whole reason I took the propshaft off was because I've done it without having to go through the inside of the cabin previously. Thought it'd be another easy removal/install....

[512BB]

You can console yourself Gorpon, that when you finally are able to refit the propshaft, your car will be transformed.

I took the opportunity to have the propshaft rebuilt on one of my cars when I had the engine out, as I noticed that one of the u/js was slack. Now that all is back in, ie engine, gearbox and prop, it is like driving a Rolls Royce in comparison to before. The whole drivetrain is so much smoother, and the iritating minor vibration on the overrun at certain rpm, that I had just gotten used to, is gone, totally different car.

It should be noted, that both weights were still in place on the prop before having it rebuilt. So for me, in the future, whenever I have an engine out, I will get the prop overhauled. Suggest all do the same, you wont regret it.

Leslie

[jono]

OP - you mentioned the prop has been out for a balance (and refurb?) - I don't suppose they renewed the yoke as well?

Reason I mention it is I purchased a new replacement (repro) yoke a few years ago from a well know parts supplier as the seal face was worn on the existing and found it was too long and hence the prop assembly would not fit between the gearbox output shaft and diff flange.

They replaced it with a good NOS items which was perfect - it would seem the yoke offset was different to the original and they were going to notify the manufacturer to amend their design.

[Gorpon73]

Thanks again for the feedback.

Yes, the balance is always such a benefit to the overall feel. It wasn't too bad as I had it done in the past, but had a small vibration at highway speed. Assuming that I could get it back in easily, I just decided to get it balanced again.

The good news is that I know the yolk splines didn't get changed/damaged when it was balanced. I removed the yolk from the shaft and reached up in the tunnel from underneath and was able to thread it and slide it on. I think they both need some extensive degreasing/cleaning. Downside is that I'll have to have the thing balanced again when I re-assemble and put some new UJ's in there while its apart.

Good thing its still February....

[joe7]

While you're at it, make sure to check that the "plug" (can't remember the actual name) in the back of the yolk is secure.

[alan.barker]

+1 a few spot welds help or Center Punch around "Welch Plug"
Alan⁰

[TrevorJones]

Hi folks

Just to add to the thread, if you do remove your Prop then carefully check the balance weight to ensure it is securely welded to the prop.
I had an issue with a severe vibration that only manifested itself at around 100mph approaching Avon rise at Castle coombe, I will admit it had me stumped for weeks having checked every thing attached to the 4 corners and found nothing. I booked another track day at CC and got my daughter to drive the car while i listened to gearbox, diff etc and thought it was originating in the diff area. Took the car home and put it on stands and ran it up in with drive shaft on - same vibration, drive shafts off - same vibration ( I have an MP4 video of this but It wont attach?).
Only thing for it was to get the engine and gearbox out to have a look at the prop! until I found the excellent article on here on how to get the prop out without removing the engine.

Sure enough the there was a nice shiny patch on the front of the prop where the balance weight should have been. The prop was a new uprated prop supplied by one of our trusted suppliers. I took it to H J Chard engineering Bristol and they fully inspected it and found the uprated tube certainly was not uprated, they changed the tube, fitted new joints and balanced it and now no issues in getting over 100mph up Avon rise.

[Gorpon73]

OK Gents. Another question here.

Regarding the drivers side tunnel port? I've removed my drivers seat, center console and carpet and don't see any port?

Could anyone possibly detail the location of this port?

Thx, DJS