Installing a Quaife QDH3Y LSD in 2007 WRX Issue

[fastzrex]

This weekend I started work on swapping the open diff in my 2007 WRX trans for a Quaife QDH3Y. The box with the new diff did not have the QDH3Y number on it but did have a number of 93.309.170.With the help of Hindsight's excellent pictorial and instructions, there were no surprises on what to expect. Inside, the trans look very good, no rough, damaged, or missing teeth, the sychros look in good shape, and the shift forks still looked like they had a lot of life left.

As recommended by Hindsight, I purchased and installed new output shaft bearings confirming bot were fully seated on the Quaife. Confirmed the bearing parts numbers were the same as the original bearings. So far, so good.

I started the process (after thorough cleaning of the entire trans). I noticed that the old diff had the output shafts about .250 above the bearings; the Quaife out shafts had only about .060 above the bearings. I double checked that the bearings were fully seated. You will see what I mean in the pictures. I did not dimensionally check the Quaife thinking there may be other differences which make the bearings sit 'higher' on the shafts ( in Hindsight's picture it appears the bearing sit lower). I continued with the install.

I was able to get zero backlash set, preloaded the bearings per the process, and then obtain the final backlash of .0058, within limits. The problem is on the left side, where the adjuster for the bearing depth is about .020" higher than the outside of the case; you barely see the o-ring. And on the right hand side, the adjuster is about .150" higher than the case and the o-ring groove would not be below the case; oil would leak out readily as there is no sealing surface for the o-ring to seat to.

I had the trans apart three times to verify everything was in order. The transmission spins smoothly and shifts easily when the case is torqued and the backlash is set, but the adjusters are higher than the case, the right side much higher than the left as noted above.

I have sent an e-mail to Quaife US support yesterday and not heard from them as of this afternoon. My impression was the diff was not machined correctly on the shafts to allow the bearings to rest lower like the stock diff. Other than the fact adjusters do not seat deep enough in the case, it looks good.

If Quaife does not respond, or just says tough luck, I am going to machine the adjusters to reduce their overall height which would allow them to seat below the case surface, the o-rings would seal correctly, adjusters would seat against the bearing cups correctly, and still obtain the proper backlash. Other than the hassle and expense of machining, I do not see any downside to this repair other than these adjusters are tied to this diff. Ideally, I could have the output shaft bearing seat area machined to allow the bearing to seat lower but I do not think I want to modify this high load area.

Any thoughts? IMG_1335[1].JPG IMG_1340[2].jpg

[Hindsight]

That definitely doesn't look right. Yes that bearing should go down further onto the differential. I would call Quaife instead of e-mailing them. I wouldn't machine the adjusters..... I would worry that something is up with the differential and potentially the bearings may shift under real-world use and cause a major issue for you. My opinion: The differential you received is defective and the manufacturer needs to make it right. I would not try to work around this problem. But that's just me.

[fastzrex]

That definitely doesn't look right. Yes that bearing should go down further onto the differential. I would call Quaife instead of e-mailing them. I wouldn't machine the adjusters..... I would worry that something is up with the differential and potentially the bearings may shift under real-world use and cause a major issue for you. My opinion: The differential you received is defective and the manufacturer needs to make it right. I would not try to work around this problem. But that's just me.

Thanks, Hindsight. I did call Quaife USA this morning and they confirmed they received my e-mail from the weekend. But 'they' (Quaife USA) must hear from Quaife UK before anything can happen. I sent more pictures again which have more views. I will update as the process continues.

[Hindsight]

Sounds good. Will keep my fingers crossed for you.

[wirenut]

I'm very interested in the response you get. I bought my QDH3Y from the same ebay vendor as you. I won't get to cracking my transmission until next month.

[fastzrex]

I'm very interested in the response you get. I bought my QDH3Y from the same ebay vendor as you. I won't get to cracking my transmission until next month.

I understand. I am just the ginny pig on Quaife support. Will update here, hopefully by the end of the week.

I suspect I am just the 'lucky' one to get a diff built late on a Friday!

[fastzrex]

I'm very interested in the response you get. I bought my QDH3Y from the same ebay vendor as you. I won't get to cracking my transmission until next month.

Wirenut, if you can open your diff box, and measure the output shaft length (the base of the shaft to the top (above bearing)), then both you and I will know more! See pic.


IMG_1340[2].jpg

[fastzrex]

After more digging at the Quaifeus.com web site, I found the specification drawing for the QDH3Y diff and verified it was for this transmission/car year (2001+). In measuring the diff I have, I am disappointed to find that the output shaft lengths (L2 and L2/A in the attached drawing) correspond to the shaft lengths on my diff (within .001 using my dial caliper). Interesting. It makes me wonder why Hindsight's picture of his Quaife shows the shafts extending beyond the bearings, like it was an earlier rendition of the QDH3Y.

Will see what the later part of the week brings.

QDH3Y.pdf

[fastzrex]

I have received feedback from Quaife UK through the US company. Basically the request is confirming vehicle type, VIN, and transmission (TY754VW7AA-TX) and giving them the dimensions for the stock vs Quaife for L1, L2, and L2/A dimensions. If you look at the diff attachment above, the L1 dimension is about .140" larger in the QDH3Y compared to the stock diff. This is close to the problem I see when trying to set backlash.

At least they replied. I hope some resolution may be worked out.

[fastzrex]

Hindsight, would you look at this 'slot' in the body of the Quaife diff to verify you had the same in your install? I mantioned it to Quaife US but have not heard from them yet about measurements or this 'slot' (about .060").


IMG_1343[1].JPG

[Hindsight]

Hard to see from the pics I have. I do remember there being a seam there, but I don't remember the gap being that big. I remember it just being a seam.

Are you sure your ring gear is fully seated?

Here are some pics I dug up that may help:

[fastzrex]

Thanks again for the pictures, Hindsight. On your suggestion I again examined the ring gear to diff 'joint'. I was not able to insert a .0015" feeler gauge at several points around the ring gear to diff joint. The attachment is what I see.


IMG_1346[1].JPG

[wirenut]

Wirenut, if you can open your diff box, and measure the output shaft length (the base of the shaft to the top (above bearing)), then both you and I will know more! See pic.


IMG_1340[2].jpg

Hey sorry for the slow response, I've been out with work. Did you have any resolution with this? I'll finally have mine all in my garage next weekend and I can check it out.

Just subscribed to the thread. (Forgot to before)

-Michael

[fastzrex]

Hey sorry for the slow response, I've been out with work. Did you have any resolution with this? I'll finally have mine all in my garage next weekend and I can check it out.

Just subscribed to the thread. (Forgot to before)

-Michael

No problem. I have had the stock diff back in again to double check I have not lost my mind, and the Quaife is just longer with the bearings seated in my case. It is a simple comparison as there are no main or input shafts in the case or ring gear on the diff; a comparison shows the Quaife is just 'longer' as the adjusters are much farther in the case with the stock differential.

I have an offer from Quaife US to send the diff to them and they will measure the Quaife diff to their drawings. I believe I will take them up on their offer.

Do you have time to just set the Quaife in your case (with bearings) and see if the adjusters will seat into the case (with the bearing seats also installed) and be at/below the case? You do not need to set preload or have any other parts in the case as the problem is not a pinion to ring gear issue.

Thanks for your help.

[fastzrex]

Hey sorry for the slow response, I've been out with work. Did you have any resolution with this? I'll finally have mine all in my garage next weekend and I can check it out.

Just subscribed to the thread. (Forgot to before)

-Michael

Here is what I see. This photo is what I have on my assembly table:

IMG_1340[2].jpg

This is from Hindsight:

QDH3Y Compare to Stock.jpg

Notice how far the shaft of the diff sticks above the bearing in the stock diff in both pictures but how it is almost flush on my Quaife diff.

[Blwalker105]

Fastzrex, I am going to be installing a Quaife and cryo-treated ring & pinion into my LGT transmission tomorrow. Based on the difference between yours and mine, I definitely agree you need to send yours back to the company.

On mine, the bearing on the stock diff was .205" below the nose and on the Quaife it is actually a little further down at .255", though the distance from the work surface to the top of both bearings is less than .010" difference.





I will take some photos tomorrow during the assembly process and backlash setting procedure.

Let me know if I can measure anything specific for you.

[Wayne Presley]

No problem. I have had the stock diff back in again to double check I have not lost my mind, and the Quaife is just longer with the bearings seated in my case. It is a simple comparison as there are no main or input shafts in the case or ring gear on the diff; a comparison shows the Quaife is just 'longer' as the adjusters are much farther in the case with the stock differential.

I have an offer from Quaife US to send the diff to them and they will measure the Quaife diff to their drawings. I believe I will take them up on their offer.

Do you have time to just set the Quaife in your case (with bearings) and see if the adjusters will seat into the case (with the bearing seats also installed) and be at/below the case? You do not need to set preload or have any other parts in the case as the problem is not a pinion to ring gear issue.

Thanks for your help.

On the one I did, the Quaife was wider from bearing face to face than the stock so I had my machine shop turn off the material until they were the same dimension from face to ring gear face. The diff is very hard and machined off slowly.

[fastzrex]

On the one I did, the Quaife was wider from bearing face to face than the stock so I had my machine shop turn off the material until they were the same dimension from face to ring gear face. The diff is very hard and machined off slowly.

Thanks, Wayne, for your valued input. That is the dimension where the trouble lies for me also, the distance between center of the output shaft bearings are about .200" greater on the Quaife compared to the stock diff. On the right side, the bearing is pressed to a 'step'; it's like they did not continue to machine the entire length of the shaft but stopped short, not allowing the bearing to seat the correct distance.

As you see in Hindsight's pictures, the right side output shaft on his Quaife is above the bearing (like the stock diff), whereas in the my picture in Post #15, the Quaife shaft is almost even with the bearing.

I assume you disassembled the diff prior to machining?

My other thought was to machine the output shaft side adjusters to a shorter dimension. What do you think of that approach instead of machining the diif output shaft?

[Wayne Presley]

I taped up the openings on the diff and then put it in the lathe. The diff is what needs to change as the bearing faces are in the wrong place to locate the ring gear

[fastzrex]

I taped up the openings on the diff and then put it in the lathe. The diff is what needs to change as the bearing faces are in the wrong place to locate the ring gear

Thanks, Wayne, I concur that would be the correct fix.

[Hindsight]

I'm starting to feel really lucky, like I was in the minority of people who got it right.

Based on what I'm seeing here, it seems like they made another production run for these diffs and when they did, they got it wrong and all of the new diffs are coming out with the bearing shoulder in the wrong spot.

[fastzrex]

I'm starting to feel really lucky, like I was in the minority of people who got it right.

Based on what I'm seeing here, it seems like they made another production run for these diffs and when they did, they got it wrong and all of the new diffs are coming out with the bearing shoulder in the wrong spot.

I sent all my final findings to Quaife USA and they are supposed to measure the right side bearing area shaft length on the units they have and respond. I measure about .726" (drawing shows .730"; L2/A in Quaife's drawing); it should be about .930" on that shaft. At that length (~.930") the diff would fit like the stock diff.

In the picture, you see the bearing seated against this 'step'; if the bearing shoulder is machined down to the diff body (~.200" for a total of ~.930), then it would be as a stock diff.

Diff Output Shaft.jpg

[fastzrex]

Fastzrex, I am going to be installing a Quaife and cryo-treated ring & pinion into my LGT transmission tomorrow. Based on the difference between yours and mine, I definitely agree you need to send yours back to the company.

On mine, the bearing on the stock diff was .205" below the nose and on the Quaife it is actually a little further down at .255", though the distance from the work surface to the top of both bearings is less than .010" difference.





I will take some photos tomorrow during the assembly process and backlash setting procedure.

Let me know if I can measure anything specific for you.

Thanks for your work and pictures. Your measurements are very close to what I would expect would be correct. Your pictures gives me more ammunition to present to Quaife USA.

[fastzrex]

I sent all my final findings to Quaife USA and they are supposed to measure the right side bearing area shaft length on the units they have and respond. I measure about .726" (drawing shows .730"; L2/A in Quaife's drawing); it should be about .930" on that shaft. At that length (~.930") the diff would fit like the stock diff.

In the picture, you see the bearing seated against this 'step'; if the bearing shoulder is machined down to the diff body (~.200" for a total of ~.930), then it would be as a stock diff.

Diff Output Shaft.jpg

I have heard back from Quaife US just a while ago and they admitted there IS a production problem with the current lot of QDH3Y units. All the units Quaife US has in stock are also of the same mis-machined lot so there are no current 'good' units available for sale. Quaife US is sending their units back to Quaife UK.

His direction is to return my unit to the vendor. Here is his statement:

"Mark,
Since there seems to be something wrong with our production lot, we will ask you to contact the company you purchased the differential from to return the differential and receive a refund.
I will have to take all the differentials I have in my stock, and send them back to Quaife for further testing.
I apologize for the inconvenience.

James Elmore
Technical Customer Service Associate
Mport-Group
Phone: 248-632-1263
[email protected]
www.mport-group.com"

This may not be an option for me as it has been two months since purchase. I will see. At the very least, Wayne validated what has been done which I can duplicate here in OKC with one of several machine shops I have dealt with.

Thanks for all of you who supplied information and pictures. It at least validated I still knew how to assemble and measure automotive parts! I was starting to wonder...

[fastzrex]

I have heard back from Quaife US just a while ago and they admitted there IS a production problem with the current lot of QDH3Y units. All the units Quaife US has in stock are also of the same mis-machined lot so there are no current 'good' units available for sale. Quaife US is sending their units back to Quaife UK.

His direction is to return my unit to the vendor. Here is his statement:

"Mark,
Since there seems to be something wrong with our production lot, we will ask you to contact the company you purchased the differential from to return the differential and receive a refund.
I will have to take all the differentials I have in my stock, and send them back to Quaife for further testing.
I apologize for the inconvenience.

James Elmore
Technical Customer Service Associate
Mport-Group
Phone: 248-632-1263
[email protected]
www.mport-group.com"

This may not be an option for me as it has been two months since purchase. I will see. At the very least, Wayne validated what has been done which I can duplicate here in OKC with one of several machine shops I have dealt with.

Thanks for all of you who supplied information and pictures. It at least validated I still knew how to assemble and measure automotive parts! I was starting to wonder...

Have heard back from my vendor (Autotech Sport Tuning), through which I purchased the Quaife diff through their eBay account. In talking with them, they were the US distributor of Quaife differentials until 2006 when they decided to start producing their own differentials and the US distributorship was transferred to a company on the East coast. They are not a Subaru specialist (specialize in water cooled VW). The Subaru Quaife differentials they have were their stock direct from the UK (purchased in 2005-06), which they are now listing on eBay. The good news is they offered to send me an RMA and refund my money for this purchase; stand up company.

I again spent some time looking, measuring the diff I have and the best course for me is to machine the shaft to obtain the correct dimension as Wayne has done in the past. I delivered the stock and Quaife diffs to my machine shop and they will machine the Quaife the same dimension from the ring gear surface to the bearing seat as the stock diff. I will update when I have it back (next week sometime).

[UnhipPopano]

Given that you have a unit that is not right and your supplier is willing to take it back, you are going to try to modify it and void all warranties you have, and in the end it may not work. Correct?

[wirenut]

Given that you have a unit that is not right and your supplier is willing to take it back, you are going to try to modify it and void all warranties you have, and in the end it may not work. Correct?

I think it will work. Why would it? I wounder how often these fail anyway. I'm going to check mine (bought from the same supplier) this weekend.

What's odd is that Qualfie international is saying that the new stock is bad and the supplier is saying that thiers came from a batch 12 years ago? Seems like they have some tolerence issues in thier manufacturing process.

[Blwalker105]

Although mine went in without a hitch, I am definitely having some misgivings about other, internal tolerance issues that may crop up down the road. I've had my unit for a year. If I were currently shopping for a LSD, I most surely know what brand I wouldn't consider.

[Wayne Presley]

Well the Quaife does have a lifetime warranty if anything does go wrong.

[Wayne Presley]

But for the money involved, I would put a six-speed that already has a limited slip in it everyday of the week

[wirenut]

But for the money involved, I would put a six-speed that already has a limited slip in it everyday of the week

Yeah I'm with you. Hindsight is 20/20 though...

If I wasnt already invested in the Mr2 shifter,cables, Mechie's shift kit, the Quaife and the transmission, I might make the change.

[fastzrex]

Given that you have a unit that is not right and your supplier is willing to take it back, you are going to try to modify it and void all warranties you have, and in the end it may not work. Correct?

Your assumption is correct. I wanted a Torsen type diff, and when I saw the one listed at the price, the purchase was easy decision at the time. Whether this is a real Quaife problem, or simply the engineers not talking to marketing to make sure what these diffs were intended to fit will probably not be known to us. Evidently, Quaife has made a QDH3Y which does fit without modification as several members have attested to here. The lot from which I have one does not fit without modification in the 5 speed transmission I have (TY754VW7AA-TX).

Why it does look like a poor bet to modify when the ability to send back for refund is available, the machining process just continues to remove a step which is not there on those units which do fit as is. The machine shop is very well equipped to examine the structure including determining the hardness; initial test precludes that the shaft has surface hardening only. I will know next week for sure. That was my only concern after the write up by Wayne.

And for sure, hindsight is 20/20 (sorry for the semi-pun!). I may have decided to do something else, but others may learn what to look for from my experience.

[fastzrex]

But for the money involved, I would put a six-speed that already has a limited slip in it everyday of the week

I would love to, and that would be preferable. At a future date, maybe.

Thanks, Wayne, for your earlier input. At least I had an option I could live with based in part on your previous experience.

[DMC7492]

I sent all my final findings to Quaife USA and they are supposed to measure the right side bearing area shaft length on the units they have and respond. I measure about .726" (drawing shows .730"; L2/A in Quaife's drawing); it should be about .930" on that shaft. At that length (~.930") the diff would fit like the stock diff.

In the picture, you see the bearing seated against this 'step'; if the bearing shoulder is machined down to the diff body (~.200" for a total of ~.930), then it would be as a stock diff.

Diff Output Shaft.jpg

Wait a minute look at this picture, these are extra parts that came with my differential only to be installed on certain years. Mine is a 2005 WRX 5 speed. I did not need these. The thin one .120" thick one .240"
I wonder if
1. You don't need them.
2. The ring was installed upside down so the chamfer was towards the bearing not the radius on the diff shaft.

IMG_1602.JPG

Things to consider, your picture looks
Like it was not assembled correctly. The bearing inner race should be tight against the spacer and the spacer should be tight against the differential. Which it is not.

[fastzrex]

Wait a minute look at this picture, these are extra parts that came with my differential only to be installed on certain years. Mine is a 2005 WRX 5 speed. I did not need these. The thin one .120" thick one .240"
I wonder if
1. You don't need them.
2. The ring was installed upside down so the chamfer was towards the bearing not the radius on the diff shaft.

IMG_1602.JPG

Things to consider, your picture looks
Like it was not assembled correctly. The bearing inner race should be tight against the spacer and the spacer should be tight against the differential. Which it is not.

Thanks for the input. My diff assembly did not include any spacers or a parts list that indicated I should have those spacers. I suspect Quaife has updated this assembly to allow other years to be included; looks like this may have solve my issue without machining the diff. The diff I have came from the distributor from a few (about six) years ago; this distributor is now on the East coast whereas the diff came from the distributor who was located on the West coast.

Quaife UK's drawing I downloaded does not indicate any spacers and the dimensions would not allow a spacer to fix my issue, it would only make the problem worse. I did confirm twice the bearings were firmly seated against the shoulder of both output shafts.

[fastzrex]

An update to my whole issue. The machine shop has successful machined the right hand diff output shaft to allow the bearing to seat in the correct position and the trial install confirms I now have the adjustability within the middle of the range. As I have moved on to other areas of the build while waiting on the diff return, I will complete the assembly of the transmission next week and update on the final assembly.

The cautionary tale is to make sure you have the newest generation of the Quaife diff assembly. As indicated by DMC7492's input above, there may be another generation of the QDH3Y Quaife differential after the unit I purchased which includes spacers to allow various years to use this same differential. This diff should have a drawing indicating (the drawing I obtained from Quaife UK does not show these spacers) that there are spacers.

[fastzrex]

In my last post on my diff issue, I indicated I would be done the following week (a month ago). Well, I decided to finish all the initial sheetmetal, add an additional aft firewall, and finish the seat attachments. With grinding, welding, sheetmetal bending, sanding, and final paint of those items being very dirty and messy, it made sense to me to finish that before doing a 'clean' assembly of vital parts.

Anyway, I successfully reinstalled the new bearings on the machined Quaife diff, and completed the final setting of preload and free play for the diff. Notice in the first picture how the output shaft is now above the bearing; before machining, it was flush at the top of the bearing. The bearing being lower on the output shaft allowed the right hand bearing adjuster to be below the surface of the transmission (where the o-ring when seal) and allow to set preload on the bearings.

Diff.jpg

The instructions from Hindsight's sticky makes this a straight forward install WHEN the parts are manufactured to correct tolerances for the model of transmission. I will finish the aft part tomorrow, and one more item is completed.


Trans.jpg

[Hindsight]

Congrats Mark. Very happy to hear you got it sorted out and that my post was helpful.

[fastzrex]

Congrats Mark. Very happy to hear you got it sorted out and that my post was helpful.

Yep, I would be lost without the input from this forum. Great expertise here as well as willingness to share. Dynamite combination. Thanks again!

And besides, it only took me three months to complete the diff install!