Ibex Overdrive

[Ibex94]

Well, the Ibex has been on the road for all of 6 weeks (and covered 1500 miles) and the first opportunity for an upgrade has presented itself!  Cue exasperated sigh from SWMBO.

I hadn't been sure how the truck would perform on the road in todays condition as it was nearly 20 years since I'd driven him and everything has doubled in power and halved the sprint to 60.  I've been really pleased he's not going to win the traffic light Grand Prix but he makes pretty good progress and with a load of sound control mat he's not too loud at 60 however it would be good to be able to cut the revs in cruise so I have been looking for an overdrive when I remember.  Anyway the planets aligned last week and I picked up a GKN / Laycock over drive - I think it cost me more in diesel to collect it than buy it.  Picked it up last night, apparently it stopped engaging for the previous owner and she didn't want to spend any money investigating and fixing it so pulled it out - I appear to have everything apart from the matching gear nob.

 

 

Started clean up and strip down this evening.  It was leaking some manky heavy oil which smells and feels like EP90 - wtf?  really grotty so wondered what I was going to find inside.  

So far it looks reasonably ok.  Piston 'o' rings look square, speed sensor looks ok, the clutch material appears to be intact.  

On the down side the fine splines which the transfer box gear runs on are well work although the splines to the R380 output shaft appear ok.

So far got as far as removing the oil pump cam but the circlip behind it has stumped me tonight.

I'll get seals and gaskets ordered up tomorrow and see what I can do about a replacement gear.

 

 

[western]

There is a gkn strip down thread by reb78 in the Defender forum that will help you strip yours apart. 

They use ATF only, don't use anything thicker. 

Also in out tech archive index is a link to the owners handbook & fitting instructions, 

[Ibex94]

1 hour ago, western said:

There is a gkn strip down thread by reb78 in the Defender forum that will help you strip yours apart. 

They use ATF only, don't use anything thicker. 

Also in out tech archive index is a link to the owners handbook & fitting instructions, 

Thanks @westernI'm watching that thread as well.  Thanks for the heads up on the manual - I'm off to find that now!

[miketomcat]

Both @TSD and @FridgeFreezer run overdrives. I'm fairly sure Dave is on his second and had stripped one when it failed though I'm not sure what make any of theirs are.

Mike

[Ibex94]

15 minutes ago, miketomcat said:

Both @TSD and @FridgeFreezer run overdrives. I'm fairly sure Dave is on his second and had stripped one when it failed though I'm not sure what make any of theirs are.

Mike

Thanks Mike, I've seen a few of TSDs posts on the subject.

[TSD]

If you've not found them already, there's a series of articles here about the Triumph Type J overdrive, which is the same core design. I noted it originally because it listed all the O-ring sizes, but it's a good coverage on stripping and reassembly too.

It's a shame you didn't get the gearknob. It's the only bit of the whole setup that I liked

[Ibex94]

Thanks @TSD I'll look that up for the O rings.

When you've had yours apart have you pulled the transfer box shafts / gear out?  did you find any wear on the splines?

 

[Ibex94]

Ok result final circlip removed and the box is now nearly completely stripped.  Used a pair of split pins to get the circlip out helped with a scriber, split pin slips over the end of the circlip and you can then work one around the shaft while leaving the second at the start end.  Worked well first try.

So with the box stripped it appears to be in remarkably good condition.  I didn't find any swarfe on the keeper magnet in the sump in the casing.  It wasn't until I pulled out the HP filter that I found any debris which I assume aluminium by its look and the fact it got past the magnet.  Cone friction material is in good condition as is the mating surface. Spray clutch feels as though it works smoothly and locks as it should.  I haven't got the solenoid off yet but that I can hear that rattle as I tilt the casing side to side I assume that a possible problem as from what I've seen on You tube the solenoid is spring biased.

So wrong oil, worn O rings and a dodgy solenoid appear to be the overdrive main issues which should be easy enough to sort.  The main problem I think is finding a replacement gear for the transfer box as the spline are reasonably worn.

[TSD]

I don't remember any particular wear on the gears of mine. It was never really A1, from new it didn't shift and and out smoothly unless dipping the clutch, but in the end it would slip when disengaged. It always got regular oil changes, but it did have a hard life, between the 2.8TGV and 33" tyres, and covering a lot of fast country roads about 90 miles a day.

The filter screen and the piston housings were gummed with alu dust suspended in the oil, and the wear was obvious in the housing. I cleaned everything up and replaced all the o-rings, but I never got it to the point I was happy with it, so I sold it on here as junk (reb78 has the back half of it, I think, and bill van snorkle got the front gear assembly in Oz)

I tried a 1.2 transfer box for a while, but even though the 2.8 could pull it easily, it put all the gear changes in the wrong place and I never liked it, so I bit the bullet and fitted a Roamerdrive. I have a standard(ish) 200tdi 90, which always felt to me like the gears were perfectly chosen and matched to the engine (though a 6th gear would be nice). Somehow I never managed to get the TGV / 33" combo in the Ibex to feel as 'right'. 

[western]

The gear knob lower part should be esdy enough to get made is a alloy machined part, the lid with switch & led should be available from Devon 4x4. Or just find a on/off switch to fit the dash or on gearlever. 

[TSD]

Alternatively, wait and see if the postman brings a small surprise package in the next few days

[Ibex94]

4 hours ago, western said:

The gear knob lower part should be esdy enough to get made is a alloy machined part, the lid with switch & led should be available from Devon 4x4. Or just find a on/off switch to fit the dash or on gearlever. 

I spoke to Devon 4x4 yesterday, sales man gave me the impression that the overdrive stock was all they had and it didn't sound as though they were looking to replenish their stock😫  Waiting for a call back.

[western]

Quite likely as GKN don't make that OD anymore & Devon 4x4 bought all the spares stock & doubt they will have parts made when stock is exhausted, Vulcan Bomber on here has diagrams for all the gaskets. 

[Ibex94]

10 hours ago, western said:

Quite likely as GKN don't make that OD anymore & Devon 4x4 bought all the spares stock & doubt they will have parts made when stock is exhausted, Vulcan Bomber on here has diagrams for all the gaskets. 

thanks Ralph