2wd R380 V8 clutch pushrod length

[mat_the_cat]

Hello, I was hoping to pick the brains of anyone wiser than me when it comes to these gearboxes...

I used to have what I now believe was a diesel 2wd R380, fitted with a V8 input shaft behind my RV8. After the gearbox seized on me (a long, painful and expensive story for me to recollect), I've ended up with a proper V8 box.

When initially fitting the original box the clutch pushrod I had, I think from an LT77 V8 box, was too long. So I settled on one something like 97mm long, from a TD5 IIRC. The difference between the original and replacement boxes is that the clutch fork pivot boss is around 20mm taller on the old box. So I now need a longer pushrod to compensate.

Assuming I now have the correct box for a V8, am I right in thinking if I get a pushrod for an SD1 LT77 box (I'm buggered if I can find the one I had 10 years ago) it should be correct? Or is there a range of lengths? I figure I can easily cut it down in situ if too long.

I have the old style cast iron release bearing carrier, with the domed release bearing if that makes a difference. The clutch fork pivot is a shade over 50mm long. Hopefully the above makes some kind of sense!

[ChrisJC]

There are a few different lengths - I googled a little as my pushrod length was not quite right for my engine / bellhousing / transmission combination. The biting point was on the floor.

So I removed the slave cylinder and measured the distance of pushrod between pivot arm and mounting face for slave cylinder, then the depth inside the cylinder (be careful not to have the piston fall out, and make sure it's fully home). I had a distance of about 105mm, so I extended my pushrod to about 97mm.

Chris.

[mat_the_cat]

Thanks for that Chris. Thinking about it logically, the pedestal the pivot pin screws to is 20mm shorter, so a pushrod 20mm longer should be what I need. I've found a 118mm version listed for an LDV, so will see how that fits.
It is just possible to change one in situ, just a bit fiddly. Or a least it was - may be more difficult now everything is 20mm more recessed!

[GDCobra]

Thanks for that Chris. Thinking about it logically, the pedestal the pivot pin screws to is 20mm shorter, so a pushrod 20mm longer should be what I need. I've found a 118mm version listed for an LDV, so will see how that fits.
It is just possible to change one in situ, just a bit fiddly. Or a least it was - may be more difficult now everything is 20mm more recessed!

Out of interest what sort of angle does the release arm sit at during its motion (start and finish) I'd assume that the first thing would be to make sure that the pivot point is the correct length to balance the arm so that the movement is balanced (going over centre during the stroke of the motion) taking into account that the release bearing is going to move rearwards as the plate wears.

[mat_the_cat]

Hmmm, good point. I guess that seeing as it worked well before, the best way to replicate the arm position is to fit a pivot pin 20mm shorter...

[GDCobra]

Hmmm, good point. I guess that seeing as it worked well before, the best way to replicate the arm position is to fit a pivot pin 20mm shorter...

Good point althogh I must admit I got a bit lost with what you have when it worked if I'm honest.

[mat_the_cat]

Sorry if I didn't explain it very well - these photos may show it better!

Old gearbox, with a taller pedestal which the pivot pin screws into:

New gearbox with shorter pedestal, effectively moving the pivot point 20mm closer to the gearbox.

I think I've probably had too long a pivot pin originally, hence having to use a short TD5 pushrod to get clutch operation. I've fitted the gearbox now, and certainly get clutch engagement and disengagement. Yet to try driving it as a fair bit of reassembly needed, but no sign of a problem yet...

[scudderfish]

Can't you get a spanner on them and swap them?

[mat_the_cat]

I have swapped them, but the difference is in the pedestal which they screw into. But I *think* it's going to be OK with the 118mm pushrod.

[scudderfish]

I have swapped them, but the difference is in the pedestal which they screw into. But I *think* it's going to be OK with the 118mm pushrod.

Ah, I see your issue now

[mat_the_cat]

This whole thing has been a pain from start to finish! It started when the gearbox developed an oil leak which I traced to the rear output seal. So I changed that, and it no longer left a puddle when parked. Happy days, I thought, and didn't check the level again. 9 months later I'm driving down the M40, 150 miles from home and the gearbox suddenly seized up on me!. Locked the rear wheels and stalled the engine, which was rather exciting. So I dipped the clutch and coasted to the hard shoulder, to wait several hours for recovery. I hadn't eaten for 11 hours, but the only food I had was raw burgers,which I wasn't *quite* desperate enough for just yet. I did however have a disposable barbecue...

My fun was almost stopped by a Traffic Officer stopping, after a car on fire had been reported. So I hopped over the fence and once on the adjoining footpath there was nothing they could do

It turned out there was a second oil leak from the breather, which only blew out whilst moving and hence didn't leave a puddle, but was enough to run the box dry after 3k miles. The input shaft bearing had certainly seen better days, and it was clearly this which had seized!

The input and layshafts had been softened by running too hot, so effectively scrap. I then bought a bargain R380 box, which turned out to be for a diesel and hence the input shaft too long, fouling on the crank and locking solid. The transmission tunnel was never designed for the gearbox, so installation is tricky to say the least. 3rd time lucky with this one which I was hoping would be a straight swap! Still, looks to be a relatively minor issue, and may even be on the road this weekend.

[ChrisJC]

Well I'm slightly intrigued as to what car that is!

Chris.

[mat_the_cat]

Well I'm slightly intrigued as to what car that is!

Any guesses? It started life as a 1.6, and there was never a factory V8 option... It was the car I bought the day of passing my test 25 years ago, so has a certain sentimental value

And to keep the thread on some kind of track, the 118mm pushrod works fine. Biting point feels normal, and I haven't had any clutch slip on a quick test drive.

[ChrisJC]

I have no idea what it is!, although I rather think I will kick myself when I find out.

Chris.

[Ian Anderson]

I thought it looked a bit like a Nissan /Datsuns Bluebird


But probably wrong