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I had a diff explode on my last 164Q... happened post accident I was taking it for one last drive, very spirited last drive, and during a hard pull in 1st gear the diff exploded causing the car to not move in any gear. I plan on buying a Q2 diff for the current 164 mostly to avoid the problems the gear set pins have on the stock diffs. Its a lot of money for one but I feel its worth it because replacing a transmission will be a lot more. if one does blow is it possible to get a new diff cover and install a new diff? or does it depend on the extent of the damage?
 

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Manual transmission requires removal of the gears to get to the diff. The case is the issue.

Correction: I mixed up the unique SAAB manual gearbox situation with the transmission fitted to the Alfa version. The SAAB has no separate diff cover but the Alfa does.

The 12 valve engine doesn't put out enough torque to justify fitting a quaife or other lsd. You will feel steering issues if you fit an lsd even if it is a quaife type. Also, the quaife is a Torsen type and will not lock the differential ( which is one reason it works better in the front axle than any other mechanical lsd) on very slippery surfaces. It biases torque by a ratio based on traction at the tire with less grip.

This is the reason for stability control electronic "lsd" being popular with makers of fwd cars now. Using the ABS accumulator pressure and the ABS hardware to apply the brake to the slipping wheel mimics a friction disc type lsd but delivers a Torsen type performance at much lower cost. No retrofits available for our older cars though.
 

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Manual transmission requires removal of the gears to get to the diff. The case is the issue.
Michael, my understanding is the diff can be removed without having to remove the rest of the gears.

George, my first diff blew in 1st gear too, just as was hitting peak power.
Today put mineral oil back in the box, junking the synthetic oil in it. Trying to organise the Quaife (Q2 requires ring-gear mod, Quaife does not). Costs about £800 plus fitting/bearings/shims... Not a cheap job by any means...
 

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I had a diff explode on my last 164Q... happened post accident I was taking it for one last drive, very spirited last drive, and during a hard pull in 1st gear the diff exploded causing the car to not move in any gear. I plan on buying a Q2 diff for the current 164 mostly to avoid the problems the gear set pins have on the stock diffs. Its a lot of money for one but I feel its worth it because replacing a transmission will be a lot more. if one does blow is it possible to get a new diff cover and install a new diff? or does it depend on the extent of the damage?
I think when diffs blow they blow a hole in the casing of the main box - which can potentially be repaired but cost wise, if means removal of more than the diff, prob best to source a replacement box. It's why I am trying my best not to blow this poorly diff - to preserve the casing.
 

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Michael, my understanding is the diff can be removed without having to remove the rest of the gears.

George, my first diff blew in 1st gear too, just as was hitting peak power.
Today put mineral oil back in the box, junking the synthetic oil in it. Trying to organise the Quaife (Q2 requires ring-gear mod, Quaife does not). Costs about £800 plus fitting/bearings/shims... Not a cheap job by any means...
Didn’t know about the quaife diff I’ll have to look into that. Is it as robust as the Q2? Most of the reason I want the Q2 if for reliability more than performance although from what I’ve been told it does completely change the handling of the car for the better.
And yes first gear makes sense because there’s a ton of torque going into it. One of my coworkers friends had a 164 as his first car about 15 years ago and he said the end of his car was also the diff while doing a burnout. I think it’s fair to say these diffs don’t hold up well to abuse.
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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"I think it’s fair to say these diffs don’t hold up well to abuse"

I would surmise that is the reason Alfa continually stiffened the casing for the diff, if nothing else, according to the explanations stated in the eper. As the power increased in the various models, from the B and L, to the S, then the LS, and then the Q, the parts listed in the eper had mods referenced, stated as stiffening the casings, etc.

I think Jason (Alfissimo) installed a Quaife in a 164. You might ask him about his experience with that.

I have 198k miles on the trans/diff of my 91S, and I always hope that if it hasn't gone by this time, it isn't going to. Of course, I may drive fast sometimes, but I don't do burnouts in 1st gear or things like that. No track time. No fierce spinning of a wheel. The car is simply not a dragster. Hondas can pull away with little trouble, lol.
 

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If you didn't blow the existing differential and damage transmission case or differential rear gear or pinion gear on input shaft you can remove L/H stub axle, R/H intermediate shaft and differential case cover with the tranny in the car.

You then install original ring gear and nylon speedo drive gear on new Q2 differential.
 

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1991 164L
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Thanks, Steve. Am hoping not blowing the diff will let it be done this way. Is it possible to shim/change the bearings this way too?
Yes, be difficult to measure depth between outer edge of R/H bearing race and case and do the math to get shim thickness. Normal way is to have tranny laying on work bench with left side down so differential laying weight in left bearing race.
 
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