Merging 1990 N/A 5MT with 1991 SS EAT

[musketeerracing]

OK - I've been searching on the forums for this particular info but I can't really find it.

You may recall I have my lovely little 1990 5MT N/A.

Now I can get a 1991 4EAT Turbo.

But of course I want a 5MT Turbo.


So here's what I believe, but need confirmed:

1. My N/A is a 4.11 with open rear diff and viscous centre.

2. The Turbo is a 3.90 with a viscous rear and viscous centre

3. I could use my 5MT in the Turbo, but the gearbox is a bit weaker than the Turbo 5MT

4. To put my 5MT in the Turbo, I'd have to take the front axles, driveshaft, flywheel, clutch, pedal box, and rear diff too, so I'd end up with an open rear diff.

5. If I found a Turbo 5MT gearbox alone, the front diff would be 3.90 and I could use the rear LSD from the 4EAT, but of course not the 4EAT front shafts or driveshafts.


And now pure questions:

6. Can you put 4.11 ring and pinion in the rear LSD?

7. How much of a pain, really, is the 4EAT to 5MT swap?

8. Am I better off taking the engine, brakes, and rear diff from the Turbo and putting them on the N/A (suitably changing the rear ring and pinion to 4.11)?


Any other advice to optimize this situation? If I could end up with a viable N/A 4EAT car to sell that would be good too.

Have to move quick on the turbo so all advice ASAP appreciated.

ACP

[THAWA]

1 yes
2 no, very high chances of it being viscous rear, but the center is a multiplate transfer clutch system
3 yes
4 the front axles are the same 5mt or 4eat, but the rest is correct
5 you could use the front shafts, but not the driveshaft. You need a legacy 5mt driveshaft
6 yes, but it might be easier to put the LSD part from the 4eat into your rear diff
7 I dont know about the 4eat to 5mt swap, but I would assume only slightly harder than the 5mt to 4eat swap. You have to do more wiring
8 tranny swaps aren't much fun but I dunno how hard an engine swap or converting a diff is either It might be easier to just swap engine and brakes.

What's wrong with the tubro that you only want to use the powertrain?

[vrg3]

3. I could use my 5MT in the Turbo, but the gearbox is a bit weaker than the Turbo 5MT

And, the Turbo 5MT uses a stronger clutch design than the NA 5MT.

4. To put my 5MT in the Turbo, I'd have to take the front axles, driveshaft, flywheel, clutch, pedal box, and rear diff too, so I'd end up with an open rear diff.

I don't think you'd have to take the axles.

6. Can you put 4.11 ring and pinion in the rear LSD?

I think you'd do it the other way around: http://bbs.legacycentral.org/viewtopic.php?t=1530

8. Am I better off taking the engine, brakes, and rear diff from the Turbo and putting them on the N/A (suitably changing the rear ring and pinion to 4.11)?

In my opinion this is a judgement call you have to make yourself based on the conditions of the vehicles.

[THAWA]

beatcha

[musketeerracing]

I KNEW I could count on you guys.

The Turbo actually looks pretty good. Better body than my N/A but i haven't looked underneath yet.

1. But he's talking about a valve noise, though. How concerned should I be?? I've read some of the lifter problem threads. What fails?

2. Can you swap the front ratio in a 5MT Turbo trans from 3.90 to the 4.11 out of a 5MT N/A? Like, is anyone driving around with an SS with 4.11?


You guys are great.

A

[THAWA]

if it's just the lifters you can replace those with much less head ache than a tranny swap. YOu could even drive on them for quite a while. Or it could be low on oil and that's why it's making the noise.

[vrg3]

THAWA - But I had the link to ciper's post!

ACP - Most of the time I think it's just that the lifters need to be bled. You take them out and submerge them in motor oil while pressing them in.

Sometimes just doing a Sea Foam treatment seems to help the problem too.

One of the biggest issues in judging which car's in better shape would be how much rust there is, so definitely take a look underneath the cars.

Have you driven a turbo with a 4EAT? Even if you generally prefer stickshifts, you might actually find you like the 4EAT when it's got a turbo to go with it. There's nothing like building boost while not moving.

[musketeerracing]

Oops, thanks. Modified the question to include ratios....

And new question: so the lifters get noisy but still drive for a while?

[THAWA]

you can swap out the front axle ratio, but then you'd have to take apart the whole tranny, and all that mess. also I'm not sure if the gears needed from your 5mt would match up with the ones for the 4eat. Dunno what that'd do to the individual gear ratios either. I'm pretty sure everyone on the board has at LEAST one lifter that needs to be replaced.

[Flip_x]

I think your right about the lifter part Thawa. because my engine just started to click some times now =(.

[Legacy777]

5 you could use the front shafts, but not the driveshaft. You need a legacy 5mt driveshaft

What's different about the driveshaft?

On another related question. Someone on the bcbf list got a used JDM tranny. His 92 has 3.9 gears, and I'm pretty sure the JDM one has 4.111. So he's either out the tranny, or buy a diff to match the tranny. Could he use the 4.111 diff I have in the donor car even though it's from a MT, and use it in his AT, with the JDM AT?

[georryan]

I don't see any reason why that wouldn't work Josh. The diffs should be the same its the driveshaft from the diff to the tranny that may be different leangths (manual vs auto driveshaft). That's how I understand it at least.

[evolutionmovement]

The top ends of these engines are tough. There's the lifter noise issue, but it doesn't seem to affect performance. I did burn out an exhaust valve on my N/A ... after almost 250k mi of abuse. At the end, it used a quart of oil every other day for a few days and then finally let go after holding it near second gear redline around a long, tight entrance ramp and then accelerating through redline in third to merge. I did this same thing daily for years.

Took the heads off and apart and there is NO detectable wear on the cam lobes! Crosshatching in the cylinders, too, but that's not relevant . And yet nobody wants to take this beautiful engine:(.

Steve

[THAWA]

5 you could use the front shafts, but not the driveshaft. You need a legacy 5mt driveshaft

What's different about the driveshaft?

On another related question. Someone on the bcbf list got a used JDM tranny. His 92 has 3.9 gears, and I'm pretty sure the JDM one has 4.111. So he's either out the tranny, or buy a diff to match the tranny. Could he use the 4.111 diff I have in the donor car even though it's from a MT, and use it in his AT, with the JDM AT?

just what ryan said, there's a different length between auto and 5speed manual driveshafts and there's also a different length between different generations and definately different models. Impreza's have the shortest, and svx's and 2nd gen legacys ave the longest (I believe). Also note that 6 speed manuals have the same legnth driveshaft (and tranny for that matter) as automatics. One other difference is the type of joints used. The 5mt driveshafts I've seen have all had 3 ujoints, one in the front, one in the middle and one in the rear. The 4eat driveshafts I've seen have had two ujoints one front and other rear, and a cv type joint in the middle.

and also what ryan said, yes you can use the same diff. I'm using my original 4.111 diff with a 5mt

[musketeerracing]

OK - I bought the damn thing for $650. Runs and drives but i thinkn there's torque bind and def. head noise bigger than a lifter (got the price down!). DOES HAVE LSD WHOO-HOO!

I will be posting a LOT more soon...!