Thank you very much for your work for this community. Next question is how hard is it to change these synchros? Does it need any special tools?

 

Various press tools are needed to dismantle the gear packs. Reverse is the easy one - you can tap the shaft out of the bearing in a vice, then the synchro can be repalced

Broken piece on bench

synchro packs look like this:

 

Nice work man.

 

Bump for updates.

Will buy a set of carbon synchros.

3rd gear double cone can be used on 4-6 correct?

Leave no stone unturned

 

Bump for updates.

Will buy a set of carbon synchros.

3rd gear double cone can be used on 4-6 correct?

Leave no stone unturned

I will try to get measurements on the carbon synchros this evening.

3rd gear synchros cannot be used on 4-6.
1st and 2nd gear synchros are interchangeable.
3rd gear is unique.
4th, 5th, 6th, and reverse are interchangeable.

 

"The Synchronizer unit is a modular system. This makes it easier to upgrade..."

Along with the pictures, it makes it sound as if 4+ could be doubled.
Not specifically needed, as the ratio change is smaller(er), gears are lighter... but would still be nice.

The CD009 Nissan transmissions couldn't add enough "Baulk" rings.

https://cdn.z1motorsports.com/upload/Z1_VQ_Transmission_Guide.pdf

Laughed at this old picture..Dreaming of using M56 1-2

 

"The Synchronizer unit is a modular system. This makes it easier to upgrade..."

Along with the pictures, it makes it sound as if 4+ could be doubled.
Not specifically needed, as the ratio change is smaller(er), gears are lighter... but would still be nice.

We haven't had any confirmed options so I really can't say that I'd blame you for trying.
It is modular in that it may work if you swapped the entire synchro hub assembly and cones. It may have required that you modify the 4/5/6/R shift forks, as well. Then there may also have been some negative impact on the driving/shifting experience. In any case, that's all moot now.
Top left: 3rd gear synchro set (note the two friction surfaces);
Top right: 4/5/6/R synchro set (note the single friction surface);
Bottom left: 3rd gear synchro set (note the (8+1) tooth pattern);
Bottom right: 4/5/6/R synchro set (note the 8 tooth pattern);

 

...I can relate to hunting for options. I took some very rough measurements to send to a couple of vendors/manufacturers. Synchrotech has been very helpful in this process so I'm glad that they have also turned out to be the only manufacturer with ALL of the carbon friction rings that we need! I sent these slides with my super rough caliper measurements from 1/2. I wasn't even sure if they'd respond to my email 😆 They did, and said that they had one that they believed would fit. I ordered it and compared it against my OEM unit when it arrived. On comparison, it looked good so I went ahead and sent them the 1/2 synchros, 3rd synchro, and 4/5/6/R synchros. They confirmed that they had options that looked to be a proper fit for our cars, for all gears. I ordered the remaining synchros based on their feedback. It looks like we have a winner.

They get high praise, from the Ford/Getrag MMT6 tuner community. Mountune, Pumaspeed, and a lot of the other outfits that cater to the MMT6 cars trust them as a manufacturer.

ave their trust

 

Does the 3rd gear synchro pegs physically fit 4th gear?

Is the 3-4 hub+slider asymmetric to make up for the +1?

Try putting the 3-4 slider over the 3-4 hub both ways, and then over the 4th gear with the 3rd gear synchro.

Ahh, you're making me want to tear mine down!

Excellent work you are doing here!
Only took 2 decades of scrapping them for more used crap, before we get a proper upgrade!! Ahahhah


Many transmissions, 3-4 can be flipped, swapped, and sometimes 5-6 as well.
Shafts and gears from other generation cases can be used if the bore centerlines are the same with proper shimming. Very common in the Honda world.

 

Does the 3rd gear synchro pegs physically fit 4th gear?

Is the 3-4 hub+slider asymmetric to make up for the +1?

Try putting the 3-4 slider over the 3-4 hub both ways, and then over the 4th gear with the 3rd gear synchro.

The 3rd gear friction ring does sit in the 4-R block ring. That said, the 4th gear ring is .5mm taller and its inner surface is bare metal.

 

The 1/2 and 4/5/6/R Synchrotech friction rings are identical to OEM but even with that being the case, they can't yet advertise them as being compatible with the M66. At least not until they have been tested on a running vehicle. The only difference that I have found is in the 3rd gear ring. Theirs is slightly taller than the OEM unit. The reference tabs/blocks are 10.45mm vs. 10.25mm. The valleys are 6.85mm vs 6.3mm. I don't believe that this represents a problem, for a couple of reasons. The first reason is that the difference in the tab height strikes me as being too small to be of any consequence. The second reason is that looking at the way they sit in the blocker ring, the actual amount of the friction surface contact appears to be comparable.
1/2:

3:

4/5/6/R:

 

.. Yeah,,... thats the difference between single and double synchros..
I don't get what you are saying? Or why you are telling me that.

Does the entire 3rd gear synchro assembly fit on the 4th gear? and slider go over?
Is there an appropriate ledge on the 4th gear assembly to hold tension against the (3rd) inner synchro ring?

Show us the 3-4 gear, and both sides of the slider

 

I have a few of the internal parts within easy reach in my garage but most of the parts, including 4th gear, are in storage. I've got quite a bit on my plate so I will not be able to measure/compare for that synchro fitment anytime soon. If anyone else has the parts and can take a look, please chime in as I am certain that others will also find the information useful.

For now, I can only say that the 3rd gear synchro and 4/5/6/R synchro to have the same diameter and tooth position when positioned one against the other. The cone may need to be modified but I believe that the 3rd gear double synchro will work.

 

Hate to spam my own thread but if anyone happens to be looking for a set of M66 internals in preparation for a build or to repair a blown gearbox, I'm selling a set that's in excellent condition.

M66 Gearbox Internals (Shipping Included)

I will not respond to posts/messages asking if I still have this. I will mark this listing as "SOLD" as soon as someone buys them. Price includes shipping in CONUS. Up for sale is a set of M66C internals. Ideal for anyone who has wrecked their gearbox and wants to replace the internals without...

www.swedespeed.com

 

This is awesome information. Just curious though. Any idea where to purchase new gears for this transmission? I cannot seem to find anywhere to get them. I do not need them but I am purchasing a S60R with the 6 speed and 169,000 miles. Looking for sources to make sure all my bases are covered. Any help is appreciated.

 

I got my taller replacement 6th gear from Ganzeboom. I think they mostly sell to businesses rather than individuals, but when I contacted them asking about an order they were able to make it work.

And FWIW, since I realize I never followed up here with the results of that...

Having now put a couple thousand miles on it with the tall (27/50t) 6th gear, I'd say I'm glad I did it, and would do it again, but it might not be for everyone. If I could pick my ideal ratio I'd probably go with something in between the factory M66C 6th gear ratio (28/40t I think) and what I've got now, and closer to the 27/50t gears, but maybe not quite so tall. Where I live (Seattle area) most of the highways are 60 zones, with traffic often only going 50 or 55, and at those kinds of speeds the tall 6th is often too high to really be usable -- the combination of the gearing (dis)advantage and being at ~1700RPM or so leads to...not a lot of effective torque to the wheels, so I usually leave it in 5th until I'm over 60MPH. It's great once I get out of town on to higher-speed stretches though -- it isn't uncommon that I need to drop into 5th on a steeper incline, but if I were bothered by needing to shift my own gears I wouldn't have spent the extra time hunting down a manual...

 

I've noticed both here and in the manual there is a lack of various torque specs, and what preload the various shafts are supposed to have.

So question to others, what numbers did you guys use during your rebuild, and where did you get them?


In general, I'd think torque specs are an easier matter as worst-case one can use the M-sizing torque guide that's in the manual, so at least one wouldn't strip out any threads on anything aluminum. Of course, for sake of example, if there's something like an M14 bolt that held on a part that came off fairly easy, it's probably not going need 150 Nm / 110 ftlb.

On the other hand, an incorrect preload can cause some real harm, namely grenading the transmission...

~~~ Preloading; Where some minor interference is added in to make sure the part is under no circumstances "loose" during operation, usually on the order of 10th or 100th of mm's. On manual transmissions this would be done by shimming the shaft to some spec, so it may say +0.10mm for example. Too low, and the shaft will dance, gear mesh will be off, and the transmission grenades. Too high, bearings can deform, not get enough lubrication, can bind up, also leading to a 'naded transmission.

 

It looks like sometime last year IPD started offering bearings & seals kits for the M66 AWD and FWD. I just updated my original post to include them. Their kit includes a shim for the input shaft.
I already have a bearings & seals kit from a different vendor so I won't be ordering theirs. If anyone buys IPD's kit, ask for the bolt torque specs and any info on the bearing preloads. I am specifically curious as to why they only include a shim for the input shaft. I have a guess but I'd rather get confirmation from them.
Also, shout out to IPD for getting a kit together. The fact that they even include a shim is an indicator that they put in some work on this.

 

Hi guys,

After reading all of this we decide to rebuild our M66 AWD out of my 2003 XC90 2.5T. A very big compliment for all your efforts and work!

I got all the parts from one of the Dutch suppliers, synchro’s and bearings and seals, that was the easy part since I’m located in the Netherlands

Now comes the cry moment, when dismantling the main shaft (outgoing shaft) the 31t gear (I think 5th gear) broke when pulling it. Ofcourse this caused all kinds of tools flying around at the shop :-(

So the gear that broke is off and we rebuilded all the synchro’s. Cannot proceed because of the missing gear and Ganzeboom and TPE cannot deliver this gear. It is a 31t gear approx 41mm high, outer diameter 75mm and inner 38mm.

Any advice on this? Can I get a FWD box and use the gear from that box? Is it somewhere available?

kind regards from the Netherlands,

Berry.

 

Unfortunately, I don't know of a source for the R's 5th gear. Ganzeboom lists a 30/46t 5th gear for the M66E and M66D variants. Part number is M66-GEAR-5TH.46. It is a different gear ratio and from what you said it may no longer be available anyway.
A used FWD M66 should work but it would have a different gear ratio.
Only the P2R and the Ford Focus ST MKII(ST225) have the 0.868:1 5th gear ratio.
Try eBay or a Volvo dismantler.

 

Thanks Matt, will continue to search for a solution and keep you posted. Kind regards Berry

 

Hi Matt,

hereby the photos of the gear. I think it is another one than the one u suggested. Will this one be the same from a fwd?

kind regards Berry

 

Hi Matt,

hereby the photos of the gear. I think it is another one than the one u suggested. Will this one be the same from a fwd?

I see, I thought you were referring to the 5th gear wheel from the input shaft. That looks like the shift gear for 5th from the output shaft. Though I would wager that you can replace that gear with one from a FWD unit, unfortunately, I can't say that with 100% certainty.

 

Hi Matt,

Thanks for guiding me a bit... bought a FWD M66 to compare. 5th gear on input and output shafts are differently, where the AWD counts 31T the FWD only has 30T and is much smaller in diameter. The 6th gear also has other ratio's than the M66AWD. We now cameup with the idea of replacing the complete 5th and 6th gear and swap them over from the FWD one. RPM will be slightly higher and top speed will be less high but thats not important.

Keep you posted and again thanks,

Berry.

 

Hi everyone,

I have a big update to share. Everything is hooked up again and it works. I had some trouble finding the right needle bearings and some other parts, but I can confirm that the revision is a success.

We took the 5th and 6th gear from a V70 M66 FWD. There is a bit more RPM drop when shifting to 5th from 4th, but it's acceptable. The RPM has dropped to approximately 1800 rpm in 6th at 100 km/h, which has led to a drop in fuel consumption. I will monitor that and share the results later.

So, all bearings, synchros, and the 5th + 6th gear have been replaced.

The transmission still shifts a bit harshly due to the new synchros, but all gears are reachable without grinding or noises. Shifting to 5th or 6th seems a bit short; you can shift to them by applying a little pressure to the right side. I think it has to do with the forks differing slightly from the fwd M66 for the 5th and 6th gear or with the shifter cables being too tight.

While we were already investing money into this old Volvo and had already exceeded the budget, we also had the steering house revised and replaced the tie rods, subframe bushes, top strut bearings, shock absorbers, all linkages, and bushings, among other things. So the front end is completely new. I've never driven a 20-year-old Volvo that feels as new on the road as this one. Such a good feeling.

Cheers all!!!!

 

Can anyone tell me if there is a way to confirm all the spider gears (I may not be getting the terminology right) are lined up before I go to install the axles? I got a used M66 that I am using for a manual swap on my VR and stupidly I rotated the transmission while trying to remove the old bad angle gear, probably a complete revolution in total, and I also inadvertently shifted the transmission several times by knocking the shift fork while I was moving the trans around. If there's a way to check this without splitting the case, I would love it.

If I have to split the case, fine, it doesn't seem that hard to do, but then how do I ensure they stay lined up after I reassemble the trans, and they don't shake out of place while I am going through the process of reinstallation into the car?

 

I have shifted gears and spun the input shaft on many transmissions including M66 without any issue of installing the CV axles. At least with the transmission assembled. You should be fine. Glück.

 

Hi all! Hoping someone here might have the experience to help me with the M66. I've got a MK1 Volvo S40 which I've converted from M56 5 speed to M66 6 speed from a MK2 Ford Focus ST225. Final drive is 4.00 While the ratios are better, they're still too tall for liking, and after a bit of searching found the XC60 came with an M66 with final drive of 4.786 which would be perfect. My plan is to swap over ring gear, upper countershaft, lower countershaft and reverse shafts - transferring the Focus ST gearset at the same time (the XC60 ratios wouldn't work for me) So question 1. Would be, is this sound logic? I'm sure it'd work but just want a sanity check. Question 2. There's an XC60 M66 gearbox local to me, and it's 'cheap' (£200). The only problem is, it's an AWD box. I know there are differences obviously, but are the shafts the same and interchangeable? I know the diff is different, but would the ring gear be the same fitment? Help greatly appreciated!

 

Im of like mind. My ideal 'box is an fwd box with R's 1-5.

I would be replacing all synchros and bearings in the process. Not sure how/if this is really possible.

Im newish to serious car work, but Ive already fitted a p2r subframe, brakes, and suspension w/bilsteins to my 99v70xc. Anything is possible when you have a cordless dremmel and a dream. Seriously hope some of these fellas can provide an answer lol

 

Ok a little bit of an update!

I did some research and made a look-up table so I can easily determine which XC60 (and XC90) model/engine/year would have the FD I'm after

After a filter, it shows all AWD between 2009 and 2015 have the 4.786 that I'm after. Turns out that cheap local AWD box is actually FWD and it appears there's a premium on the AWD boxes... The search continues for a reasonably priced one.

Here's a table to show the result of FD change based on my tyre size and ST gearset -

As this is a circuit race car, I want to be geared so that I'm just about to top out on the longest UK straight... There's no way I'm getting to 170mph without doubling my HP so this confirms I don't want to settle for anything less than the 4.786.

I've taken my ST box apart to remove 5th & 6th - that took some effort! After failing on my home made press, I took it to a friends place (he does gearbox rebuilds) and we ended up breaking teeth 🤦‍♂️

I then took it over to a local garage and borrowed the use of their 80T big boy press and managed to get them off without further damage.

Took in excess of 30T to get 6th off! Scary stuff

Anyway, now I know its a job I'm able to do, I've sourced another ST box for the 5th & 6th we broke. Fortunately local and only £50! Picked it up a couple of days ago.

All I need is to find that XC60 box and I can hopefully arrange the pieces for my short ratio box

Andy

 

Thank you very much for your work and research.Your post inspired me to bite the bullet and take the gearbox out of my XC90.
Inspired by the diagram from www.automaticchhoice.com I got the bearings from several sources,oil seals,oil and sterted the job.
When I've got to the point of changing the bearings I had the surprise to find out that the bearings from the 3rd gear shaft are bigger than the ones in the exploded view from automatic choice.What are the chances there are more types of M66?Is there any big difference between M66 FWD and AWD?

 

I've just taken apart a manual AWD gearbox from a Landrover Freelander 2 which again is an M66. They have a FD of 4.533, same as some of the volvos. Readily available so really cheap in comparison to the Volvo stuff. Casing on the bell housing side is slightly different.


Open LR gearbox (Ford Focus ST on left)

ST gearset Vs LR.

LR bell housing

Gripper diff on left, originally from a FWD S60 box, then fitted to my ST gearbox. LR AWD diff on right.

Ring gear is mounted on the opposite side of the diff flange, but the offset is the same so physically interchangeable, however the bolts are slightly larger - I've not measured yet but I think they're M11.

This means if I'm to use the LR ring gear to give me 4.533 FD I've got to drill out my gripper diff.

I'd be interested to see what the diff and ring gear look like on a Volvo AWD box, and what size bolts they use.

Still on the hunt for an XC60 AWD box to get 4.786 FD....

Andy

 

I've just taken apart a manual AWD gearbox from a Landrover Freelander 2 which again is an M66. They have a FD of 4.533, same as some of the volvos. Readily available so really cheap in comparison to the Volvo stuff. Casing on the bell housing side is slightly different.


Open LR gearbox (Ford Focus ST on left)
View attachment 258393

ST gearset Vs LR.
View attachment 258394

LR bell housing
View attachment 258392

Gripper diff on left, originally from a FWD S60 box, then fitted to my ST gearbox. LR AWD diff on right.
View attachment 258391

Ring gear is mounted on the opposite side of the diff flange, but the offset is the same so physically interchangeable, however the bolts are slightly larger - I've not measured yet but I think they're M11.

This means if I'm to use the LR ring gear to give me 4.533 FD I've got to drill out my gripper diff.

I'd be interested to see what the diff and ring gear look like on a Volvo AWD box, and what size bolts they use.

Still on the hunt for an XC60 AWD box to get 4.786 FD....

Andy

See if this helps. 2004 XC90

 

I have no clue mate. I have opened it to change the 3rd gear synchro and the bearings, couldn't do it because of the bearings on the diagram being different than the ones inside. 3 days work for nothing...

It wasn't the shaft, the OD of the bearings was different. In the diagram I had 62mm od, in the gearbox i have 72mm od... ID was the same

Sorry to hear about the bearing mismatch and thanks for sharing your findings.
An Australian poster on ozvolvo swapped an M66C(AWD) from an S60R. He listed the bearings that he used to service the gearbox:
32010X NTN 50x80x20
30306JR KOYO 30x72x20.75
30206JR KOYO 30x62x17.25
32006 X NSK 30x55x17
84548/10 KOYO 25.4x57.15x19.43
32005JR-N KOYO 24x47x15
32004JR KOYO 20x42x15
32008 XTN9/Q 40x68x19
32007J 35x62x17
328612 D/QCL7C 41x68x17.5

Like you said, the Automatic Choice diagram references component 663(X-M56.BE04) as a bearing for Output Shaft 3-4 in their M66 FWD kit. Based on your measurement and the parts list from ozvolvo, that bearing is actually Koyo 30306JR on Volvo M66C(AWD) cars. It looks like quite a few place sell that bearing.

 

Hi Matt and thanks for taking the time to reply. As I said a few posts ago, you inspired me to strip apart the gearbox.
Now I'm after a gearbox, I want to buy one, rebuild it, as I have most of the bearings and oil seals, and just swap it when it's done. Not buying anymore bearings until it's on the bench.I'll keep the tread alive, if that is ok with you.

 

Right, I finally sourced a Volvo XC60 AWD box (2012 2.4 D3 / D5244T17)

I can confirm the bearing size is also 62mm on this, same as the LR Freelander, and Ford ST (fwd).

What did surprise me (following @andreescuvm images) is that unlike the FWD gearbox and the XC90 gearbox, the crown wheel is inverted like on the Freelander and uses M11 bolts. (See image below ST on left, Freelander on right (XC60 AWD similar)

Now that I have the correct 4.786 FD box I was after, I stripped down reverse and 3/4 gears from shafts-

And combined the ST gearset onto XC60 shafts! Success!

Now I've got to borrow the big press and remove 1/5/6 and reassemble.

I also need to drill out my diff to fit the new crown wheel.

Will update once it's complete.

 

Right, I finally sourced a Volvo XC60 AWD box (2012 2.4 D3 / D5244T17)


I also need to drill out my diff to fit the new crown wheel.

Will update once it's complete.

What did you mean? Using the AWD crown wheel/bearings in an FWD casing??

 

I'm looking for the bearing number(s) for the M66 differential. Can someone post?

 

What you're looking at here is a XC60 shaft with Focus ST gearset - FINALLY!

Getting the 5th and 6th off the XC60 shaft and the ST shaft were incredibly difficult without breaking teeth - it took 3 ST gearboxes before I found success. Fortunately I didn't need to save the XC60 ones so I cut a groove in the gear to get a big bearing puller in there to provide support.

And for the ST ones?

well I didn't need the shaft from this one, so I just cut the top off which made supporting the gear easy. - In fact, where it was supported so well, it didn't let go with a massive bang like the others did - and I pressed both out at the same time!

Just got to put it back together now and hope it works and was worth the effort!

Andy

 

Nice work!

Question - did you take any pics of disassembly of the 3/4 shaft? It looks to be the same setup as reverse, remove the lock bolt, press the shaft out of the outer bearing, then slide everything off. Can you confirm that?

Reverse for reference

TIA

Hussein