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Am I Going Mad? (Subaru Diff Conversion)

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Last weekend sat a scooby diff on the bench, and bolted the rear cover plate in position. That was simple enough.

Next, took the pair of flat steel plates that had been lazercut but not bent, plus this image

http://homepages.paradise.net.nz/lghrnrm/diffplat.htm

cut almost through the bend lines and bent t to match. That is being arc welded up sometime this week. The spring mounting plate was what caused the headache. 

All the pics I have seen have the plate bent to shape eg

http://www.triumphexp.com/phorum/read.php?8,1286849

 

My plate was flat. So took measurements from a triumph diff, and cut the 2 ends off to match the height from the diff mounting "ears" ( I am using them as the reference point, and assuming that the diff rear face sits vertical, as the machined joint face does on the triumph diff).

First issue is that at std height there is not enough space to get a nut under the plate, and I would not trust tapping threads in the plate. Grrr. Gut another 1/2" and tacked onto the side plates. That problem solved.

However, the next bit is where I worry about my sanity,

Place the top section across the two uprights just like the above link. Take some measurements, again from the ears, and it is substantially forward of the std Triumph position. Maybe an inch?

This just seems wrong. Surely the transverse spring MUST be mounted in the same relative position to the chassis mounting ears? Otherwise it will put the top of the VL's forward in the arches, and cause them to try to twist, putting unnecessary stress into them? 

Anyway, after a cuppa and a kitcat, plus a bit of a discussion, we have stuck with the measurements off the Triumph diff. But does that mean many cars are working just fine with the spring mounted further forward? Am I right to copy the Triumph position? Or am I really loosing my marbles?

 

I will post a pic once I get the 2 plates back, should be this weekend. 

 

(apologies for the ramble, but this is troubling me)

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I believe that spring mount plate will bolt up regardless of orientation, but the actual mounting surface is off to one side (ie; the front). If you flip just that spring mount plate around does it solve your issue?

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Okay, ive just re-read your post and looked through my stuff. You have made a spring plate that goes straight across- from flange to flange with the spring mount in the middle. The designed item doesn't. It biases the spring toward the rear- ala triumph postion. You will need to redesign Im afraid-

Also, you have been pm'd

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Sorry for the delay And the fact my bracket isn't as pretty as the one above.

hopefully the pics show the bracket centreline is teh same distance from the bush centres on both diffs. The likely reason for the difference is that the rear housing is not a NZ one, so is probably a bit deeper shifting the diff forwards.

 

Another things I was not keen on:

1. The lack of bracing on the bracket, so 5mm thick "fishtails" have been added front and back

2. The examples I have seen of the bracket have the studs welded in place. How do you get the spring through? Or they are tapped into the bracket, but 5mm thick does not seem enough. We are adding 12mm thick plates under the bracket, drilled and tapped so it all works like the original.

3. There is no "groove" to locate the spring. You could rely on the studs, but a bit of steel is being added again to replicate the original.

 

 

I have also just measured up the scooby diff with CV's and compared it to the Triumph diff with Nicks afdapters and CVs. The Triumph diff is 4mm wider, however, the CV splined section protrudes about 5mm more either side on the scooby diff. Hopefully this is enough. A bit close, but I am feeling confident. Hopefully that confidence is not misplaced.

 

Nick may know how much "spare" there is in the volvo lobro? 

 

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post-784-0-87933500-1455888920_thumb.jpg

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Nick may know how much "spare" there is in the volvo lobro? 

 

Spare travel......?  Between very little and none.  Maybe a couple of mm either way.

 

Strongly suggest working the suspension through its full range of movement and changing everything turns sweetly throughout.

 

Nick

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Thought as much! And yes, it will get a thorough testing before being let loose on the road.

I know the volvo lobros don't have a lot of total plunge. The scooby ones have loads but looks like they will be running right at the ends. Almost considered getting a fresh snap-ring groove machined on the CV splines to get them a few mm further out the diff. Madness or genius?

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My next problemo.....

Just phoned Dave Mac re getting a propshaft made up.

he wants the dimensions of the diff flange. My measuring equipment is not up to the job (cheap vernier and a ruler!) but I am struggling to find the info anywhere. Anybody got any pointers? Don't really want to get a prop, cut the flange off and send it to him...but at a push I could send him the diff flange. Rather not though!

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Your cheap vernier should give good enough results.  He's not looking to manufacture to your dimensions, just select the nearest standard production part from his suppliers catalogue.

 

So long as you give him the spigot OD, bolt PCD and bolt spacings (like the Triumph ones they are probably not equally spaced), he should he able to work it out.  Telling him the likely donor vehicle would help too.

 

Nick

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thanks Nick,

That I can do!

Was worried they may require super-accurate measurements. 

 

Measuring PCD is not exactly easy, needs one internal and one external jaw.... (as it is impossible to measure to the hole centres with any sense)

 

Cheers

Clive

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if the holes are unequal distances just measure from hole to hole long distance and the same with the short,use the jaws against the outer or inner side of each hole then either subtract or add respectively 1x a hole diameter from the total.this will give centre to centre distance

give the prop guy these dimensions and he should be able to work out the pcd and machine the holes or find a suitable flange.

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A bit of progress today, but first some disappointing news...

The "pair" of scooby shafts I bought several years ago that were supposed to fit an LSD, one side with a stepped splined section the other not.

The stepped splines fitted fine, the normal side just would not fit with a snap-ring in the diff. And seemed to try to knock the other CV out.

 

Inside, cuppa/kitcat and ebay search to see what was what with these CV's, and I think I had been sold a pup. Another shaft ordered..... here later this week.

 

Bad news part 2. I though I had ordered a new pinion seal to go on the diff. Took it up the garage to discover it was the same part number as teh shaft seals. Checked against the actual diff pinnion, and yep, wrong one. Phoned suppier who confirmed I had indeed ordred a shaft seal, and would I like a pinnion one now? so that will be here in the week.

 

Feeling a tad despondent popped the diff brackets etc together, diff in the chassis. Spring on the diff, then popped the scooby CV on the metro shaft. Time to see if it would work. And indeed it does! there seems to be a minimum approx 6-8mm of plunge left before the balls will be up against the retaining ring, more than enough to allow for jolts etc.

 

Obviously this is just the off side, I need to check the near side will also work once the new CV arrives. More later....

post-784-0-07416200-1457202023_thumb.jpg

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looking good clive, how did you mount the bolts for the spring? a few more pics would be good. Regarding the Inner CV, mine are the same for both sides, I think the later subaru ones has one inner shaft longer than the other but not sure what car thats fitted to?

Rob

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Welded a bit of 10mm (I think) bar under the bracket that was drilled and tapped to accept the std studs. 

I keep looking at the NZ plates that appear to have the studs welded in place, and have no idea how to get the spring in the car as I always slide it in from one side.

 

Re CV's I think (bear in mind the Subaru world is a very murky world) that yours is a later diff, and uses a pair of CV's with a taper on the end like these:

http://www.ebay.co.uk/itm/97-00-SUBARU-IMPREZA-2-0-SPORT-REAR-LEFT-DRIVE-SHAFT-DRIVESHAFT-/252135844197?fits=Car+Make%3ASubaru&hash=item3ab477a965:g:KrkAAOSw5ZBWKByd

 

Wheras mine needs one like this with teh stepped spline thingy

http://www.ebay.co.uk/itm/1994-Subaru-Legacy-GT-2-0-Estate-Drivers-Offside-Rear-Drive-Shaft-/371542505219?hash=item5681a8b703:g:BzUAAOSwvUlWqeKS

 

and the other side (I think/hope/pray) which is on its way to me....(the shaft above is from the same seller, so that was a clue that this was a pair....unlike mine)

http://www.ebay.co.uk/itm/1994-Subaru-Legacy-Estate-2-0-Passenger-Nearside-Rear-Drive-Shaft-/371542505659?hash=item5681a8b8bb:g:dFAAAOSwJb9WqeLV

 

Will post some pics later....

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Ah, yes. A very timely reminder

What that doesn't show is teh type 1 VLSD short CV has a very small taper on it (at least I believe that is the case)

I have the stepped VLSD shaft and the one called a "standard 160 axle" which does not want to work!

The replacement may well be here today....

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Good news, when I popped home mid-morning to pick up the forgotten chopsaw (twit) there was a scooby driveshaft waiting in the hall. Return to work delayed 5 mins to manage to unwrap said shaft, and 10 seconds to bang it in the diff. Job done. Well, need to take the CV off and attach to R100 shaft, but that along with new prop should see it ready to all be final fitted. Props coming in at about £200 mark....

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I am looking at all new.

Dave mac charge 155+vat if I supply a donor subaru prp (fit t9 end, cut to length, new ujs, balance) or 195+vat for all new.

by the time I have had to get a prop, and send it to them, there seems little saving.

The tricky bit is the flange size, seems they rely heavily on measurements, and I have concerns about me measuring accurately enough, especially the bolt PCD!

 

My setup will have the diff flange to box oil seal at 570mm, but they will all be different.

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Pics sort of showing bracket detail

Fishtail plates added at all corners (make it more rigid) and thin strips to stop the spring twisting against the studs (like the original diff)

 

Overall the plate should sit the spring approx 20mm higher than std diff setup, ie about the same as the 3/4" lowering block I was using.

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Hi Clive ,

With Spring round the corner and watching your progress I am feeling I should be getting involved in my motor again .

Did your CV's come with clips ? One needs to be carefully selecting clips as slightly the wrong ones can leave your CV's stuck fast in your diff/LSD . ( not easy to overcome believe me ! )

My prop is 517mm T9-Subaru .

A reminder to people going Subaru , parts from Subaru are stupidly expensive , single retaining clip £7 , diff bearing £56 , so don't think maintenance will be straightforward without trawling breakers .

Out of interest the Subaru link above is the only link I have ever found that has even talked at all about the ' type 1 and type 2 ' viscous units . I have never found any information explaining details/reasonings about these two versions . It seems Subaru themselves must be very closed on info or may be one needs to speak Japanese .

Best bet is to have your Subi diff fitted with an aftermarket LSD whether Quaife , Cusco , Kaaz , Tomei , Carbonetics, M factory , Subsru or others .

Also it is regularly suggested that viscous units have a limited life so don't think that because you have found a viscous unit in a breakers that you are sorted , the fluid could be knackered and it is now acting as an open unit ( not that efficient when new ) .

Also it is also wise to take an imprint of the internal splines and ring clip grove position and compare that with your CV splines and ring clip groove position , some combinations look good and work but actually you will have very little mating spline .

Don't forget that a great deal of info on Subaru forums is flawed so triple check .

However I do have a brand new Type 1 viscous LSD unit ( 4 spider gears ) and a pair of CV's to fit I need to sell on .

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The difference between type 1 and 2 seems to be the T1 has 4 gears in teh diff, T2 has 2 and imprtantly a pin going through so there is no clear "hole" all teh way through.

T1 has one stepped spline, T2 2 identical, but see my refernce to different types. The splines are remarkably similar in length.

 

Budget is an issue too, so I am not likely to be using a new LSD! The viscous has significant resistance, so should be adequate for a light car like the spit. bear in mind it was designed for a car twice as heavy! A new LSD would probably be like a welded diff in a spit.

 

Have you driven a used LSD in a spit? I ask as I know people who have and have no complaints, certainly when teh diffs are cheap.

 

As to clips, yes I have appropriate clips. Be warned, the stepped spline is different to the other side (obviosu when you see the groove depth on teh CV, and feel the depths in the diff) and goodness knows why!

 

BTW had the diff apart, the 3.9 started as an open diff, and I have fitted and set the diff up with the LSD/ Just needed a shim off one side....

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I don't know about the Scooby diff lsd viscous unit but the ford ones can be resurrected with new fluid or even uprated if you prefer. 

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