Many shades of Red (now one shade of Green)

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While waiting for the exhaust manifold to be repaired and modified for the T25 flange I started to look at something I have put off for 10 years -
the rear differential I've always had a clunk from the driveshaft, diff fluid dripping from the torque tube flange, the (original?) CV boots are a bit cracked but surprisingly not torn, there are sometimes odd groans at certain speeds, and I would like to swap to the 4.22 gears I bought many years ago.

So here we go (I got my work cut out), using the great guide from Kev on StarquestClub. (https://www.starquestclub.com/forum/ind ... rque-tube/)

Cracking the nuts loose that hold the diff to the top of the diff mounts. From memory a 6" extensions piece fitted perfectly and allowed a long bar out of the wheel well to break the bolts free. Did not want to drop the petrol tank again. (You can see I hate working under cars and have put lots of "extra" safety in place with sacks of logs )



Getting the bolts off from the torque tube to diff were pretty hard, especailly the ones at the top! I used a combination of 2x12" extensions, a short "wobble" extension and a mains powered 500nm impact gun (ugga dugga?!).

The bolts on the drive shaft were going well, some felt pretty stiff but then the enevitable happened, one let go and snapped. I thought giving it a whack with a lump hammer would do it, but nope. I didn't want to take the hub off, so I cut/ground it down with an angle grinder thinking I could whack with a drift would do it, but nope! It was well and truely stuck in there! I had to drill in 0.5mm increments from the rear, as it broke through the side of the bolt (I always end up wandering slightly off centre) I was able to knock it out. Quite a waste of time.



With the diff lowered down on a trolley jack, It was time to start looking at what I needed to do.

First off, my UJ on the prop shaft were really notchy. Looks like they are 25x76.8mm UJ as used on lots of other Mitsubishis, sometimes written as 25x77mm. I'll need to order a couple of those, think FEBEST ASM-91 will do it.

The Torque Tube was full of orange looking grot, which was actually magnetic so probably a combination of old grease, diff fluid, metal fillings and rust. Hmm, I wonder where the metal filings came from? I could probably win some award for worst torque tube with that. With no option to find one in the UK it was back to importing from the States, where the Chrsyler Conquest seems plentiful. With weight, poor exchange rate and import costs it's not cheap but I saw no other option.







Sludge river down the torque tube


Getting the torque tube nut off was fairly straight forward, I had some funny homemade looking tool from years ago for holding a pulley and it worked wonders for bolting to the driveshaft flange, using the weight of my Honda daily to hold steady and a long pole to crack it loose.



The Half-Shafts / Axle Shafts were covered in waxoil (a debateable underbody rust preventative), but they didn't think to rotate the shafts so they are only coated on one side! I don't know how much it takes to throw balance out but it was fairly thick stuff!



Cutting the boots off, one of the CV joints was like a brown mayonaise inside! Litreally tipped water out. The CV boot was held on with a cable tie so guess it was loose at some point, water got in and it never got back out again.



To be continued.....

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As I intend to swap to 4.22 gears I need to correct the speedo. I don't know what happened but I could not unscrew the speedo cable from the speedo gear on the transmission. I tried everything and even got to the point of thinking it was one piece of metal! I ended up having to slice the nut sideways and "Expand" it slightly with a screwdriver and then it unscrewed perfectly. I think it is still usuable.

The original (on the left) is 22 Teeth. It has the longer body as it has the coil to pickup the speed for the ABS (or maybe cruise control I forget). I bought a 29 teeth from a Pajero or something, on the right. 29 teeth is a bit much, ideal ratio is 26-27 teeth. Anyway, turns out it doesn't fit as the body with the o-ring is larger diameter to the Starion! I looked at the Mitsubishi parts catalogue and guessed MD705427 (last two numbers in the part number is number of teeth). I think this is from a very early 80s L200 or Pajero but as these are pretty hard to find I thought I would try buy this part new. I ended up buying it from Partsouq in Dubai! The UK dealers didn't seem to be able to order it or said it didn't exist.

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In more preperation rebuilding the diff is measuring the drag on the pinion when selecting shims, specifically the "crush" shim that sits between the two taper bearings. The height of that shim sets how much bearing preload and thus the drag. I couldn't find a tool like Kev had so ended up making one! I needed something to measure Newton Cm (tiny), so I dug out some old springs and calculated their spring tension by measuring their initial tension (weight required to just shine a light through the coils) and then the weight to extend the spring a certain length. I used things around the house to measure it all, like the calibrated tea cup I can attach this spring at a position on a 1/2" Socket T-Bar and by seeing how much it extends by get an idea of the drag.

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...and to making things quicker,cheaper,easier when changing shims for the pinion height I took a brand new Koyo bearing and cut the cage off and put a slice through it with an angle grider. I was hoping to file it out by the 0.1mm-0.2mm required to prevent it being an interference fit but the harded steel was way too hard. This seems to work well, tap a screwdriver in and it opens it up. I have to stick the rollers back on with grease as the cage is too hard to bend back on. When the right shim is found I plan to freeze the shaft and heat the bearing in the oven and it should just drop into position.

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Dissasembly of the torque tube and diff is pretty much as per FSM / Kevs guide so won't bore you with that. After cleaning up parts and scraping any loose rust off, I gave them a coat of 2 part epoxy paint (brushed on).

The torque tube got a new bearing, the old one felt fine but as it had been covered in the remains of torque tube splines I thought best replace it. It's an easy one to do and cheap. Got a Koyo brand one, just like original and it even says "Made in Japan" on it!



Drive shafts were cleaned up. I got as much of the old grease out, especailly so on the one that had water in. Stuck some new moly grease in and used the universal CV boot kit with the traffic cone style applicator. First one took me over an hour, one ripped. I realsied you need to grease up the cone and every single bit of the CV boot, inside all the ridges etc for it to slide over. I did both CV boots from the inner end as the outer end flange would have got in the way. Not sure how much I trust these new CV boots but the shafts are pretty easy to take off now I've done it once and know what I'm doing. I used rubber gloves while applying grease and then switched to mechanics gloves for gripping the CV boot to get it over the cone.

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Excellent build thread!!!
You may hate life after a 4.22 diff ratio swap.
Double the torque on a sohc & stock 5spd.... put the clock on it = disappointing results. May 'feel' quicker... for the 1st few feet

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Excellent build thread!!!
You may hate life after a 4.22 diff ratio swap.
Double the torque on a sohc & stock 5spd.... put the clock on it = disappointing results. May 'feel' quicker... for the 1st few feet

Thanks!
It would be better if my last set of images worked! Seems like OneDrive have changed the format of the embed reference and it's not going to work. Hopefully this will revert back and I can go through and update the photos.

Sure, 4.22 will not have the top speed but I don't want top speed. 4.22 may be slower as changing gear lots of times on the Starion box is going to cost time. However, I'm just building this for fun, the experience and something to "tinker" on so I thought I'd give it a go I'm sure the Ralliart cars Ran 4.1 or 4.2 gears so thats bonus points too

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New UJ's fitted and a quick coat of Matt Black. Actually the old UJs didn't look too bad, they seemed less "notchy" once I released the circlips.



Looks like I might be waiting for Shims from Japan for a few weeks still

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I'm sure the Ralliart cars Ran 4.1 or 4.2 gears so thats bonus points too

Probably no interest in life under 4000rpm either. There is magic in a "good" camshaft, allowing the sohc to 'pull' past 7500
With a top-heavy power delivery, a 4.2 would shine. Dunno how/if the stock 5spd would like shifting up there tho
We commoners lack the quality sohc cam/valvetrain R&D, Ralliart benefitted from. Very rare to see, but they do exist

Starions around the world salute your stella efforts :)

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Asked the neighbour for a favour to weld my old pinion spline coupler to an old length of metal tube, a useful tool to torque up that pinion nut!



...and a parcel arrived all the way from Japan! Complete set of shims.



I measured each one in the set.



Setting up the preload on the side bearings. I inserted the two smallest shims and measured the gap, making sure everything is seated well. Then picked a pair to give me the 0.1mm preload. (i'll put up a table when its all setup showing the measurments and steps)



You can see in that photo I crushed the end of the spare copper central heating pipe to use instead of the brass rod they mention in the FSM. I ignored the use of a brass rod and then accidently knicked a part of the diff as I was driving a bearing out. Luckilly it was on an area that didn't matter but it made me re-think that decision

[fugazi]

Good work popup!
I need to get at it toooo..... soon... perhaps....

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I got stuck in with the shims. Reading the contact pattern with the yellow grease stuff is a little tricky, its hard to know when its good or good enough Changing the two LH/RH shims is pretty quick 15 minutes or so but doing that pinion one is a bit of a chore as you then have to pull the pinion coupler off the splined bit. In all thats probably 1-2 hours.

It was good to change things and seeing it having the intended change though, I don't think I would have been happy just chucking it in without buying the shim kit. It probably would be OK, espcially for the limited mileage that it sees. The table below shows the sort of thought process, each row I changed a variable and observed the changes it had. Apparantly for used gears being nearer to the toe of the gear wheel is preferable.



Used this as a guide for contact patterns along with the one in the FSM.

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Now I was done with the Split / Removable bearing it was time to push on the proper bearing. Exactly the same make (Koyo) so fingers crossed their tolerances are tiny and I won't need to change that one shim between the pinion gear and bearing.

I measured something like 0.15 or 0.2mm difference in size of the bearing hole and the shaft diameter. I did a quick google of steel expansion coefficients and stuck the shaft in the freezer (about -20C) and the bearing in the oven at 200C. Got everything setup, oven gloves on and a quick dash from the oven and a slammed it down over the shaft and it was seated! Science

The cardboard box in the background does not contain a 6 bolt 4G64 crank, honestly!

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Started putting the diff back together. Chased the threads on the drive gear, this is essential. There is so much old threadlocker in the holes, they would give you a false torque reading. Put new Loctite 270 in.



Unfortunately when changing the bearing, it did seem to mess up my shims! I couldn't get the required drag on the pinion so had to start decreasing the shim. I was worried this would be messing up the actual pinion height (which influences the contact pattern) but it seemed to be OK. I can't change the shim under the bearing as it destroys the bearing in the process and you could just end up going round in circles. In the factory they have tools (see FSM) made by millers for calculating shim height. The tools are actually kicking about on USA ebay but I think it's time to just send it



New oil seals, pretty easy to find the Mitusibshi ones as seemed to come from Evo, Delica etc



Making a new gasket, and also put RTV on it.

[fugazi]

The cardboard box in the background does not contain a 6 bolt 4G64 crank, honestly!

No... probably not!
Because that would be you having Unobtainium here in Europe... or wherethefuckelse...
Find me one and I'll spank you for free... how-ever-long-you'd-like!