Gearbox Mount Issue
 

Hey,

I have a problem trying to get the right Y-Block mount for my transmission mount. I have a 1987 Mazda Rx7 that was originally an automatic car that I have got converted to a manual.

I believe that the gearbox is a Series 4 Turbo one but as I didn't source it I can't confirm that. The Y-Block part number is #39-3400-FBY1 and its approx 2 times to long. You can see it here http://www.mazdatrix.com/GetPrice.asp.

I have attached some photos showing my setup in the hope that someone can tell me what is wrong. I have also tried a friends Series 5 mount with no luck. Let me know if anyone needs some more information.

It is an S4 TII transmission. An S5 would have the Y-bracket mounted via 4 bolts on the edges, while the S4 mounts with 2 bolts on the bottom (unless someone swaps tail housings).

Will the 4 pieces (mount, bracket, 2 y-blocks) bolt together if you remove it all from the car/transmission? It looks like your transmission is drooping, and I wouldn't be surprised if that bushing is blown out if it was driven that way.

No, the 4 pieces won't bolt together out of the car. I don't have any photos of that but the gap between the transmission cradle and the crossmember is about half the size of the Mazdatrix mounts I have. I can get a photo of it if it would help to show what happens.

Here's a picture of the y-bracket and blocks on my S4 TII transmission. I can see that your y-bracket is definitely different. The sides extend up further. Maybe your bracket came from an auto transmission?

https://www.rx7club.com/attachment.p...1&d=1302836032

Yea it looks quite a bit different! I've attached an image of the y-mount I have with the measurement. I might try and pull my crossmember of my transmission in the weekend and get some photos and measurements off it out of the car. I need to figure out what sort of crossmember I have as well, hopefully its a S4 manual one.

I really want to get it sorted out, can't drive it the way it is at the moment...

The y-blocks on my S4 TII transmission are 35mm tall too. I think I have an S4 TII crossmember somewhere too. If I can find it, I'll take some pictures for you.

hey, I took the crossmember and cradle out of my car today and took some photos. Sorry that some are blurry it's a bit of a mission taking photos on my cellphone.

I'm not sure whether the crossmember I have is series 4 or not. And you can see in the photo with the ruler that the gap between the cradle and crossmember is only 15mm approx. And from the photo attached before that the bush is 35mm... No way I can get it to fit.

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It looks to me like you have an S5 crossmember, and an S4 (auto?) y-bracket. You can't mix the two, as the S4 brackets are wider to accommodate the 2 bolts on the bottom.

I found this image of an S5 y-bracket. There are no measurements, but your bracket is noticeably wider since the stud and blocks are the same size. I think your solution is going to be buying an S4 crossmember, which will fit your wider bracket.

https://www.rx7club.com/attachment.p...1&d=1302974865

Karl..get a hold of 10aeRX7(Bruno)
he had a Auto car and converted it to Manual..he had to build a mount for it,,maybe he has pics???

Hey yea I sent 10aeRX7 a message about his mount. I took some pictures of another crossmember and Y-Bracket that I was told was a Series 5 one. Can anyone confirm what they are?

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An image of what I should have as a crossmember and y-bracket to suit my gearbox and shell would be great to. Just want to source some and get them fitted so I can drive the damn thing :). Thanks for all the help so far.

That Y bracket is for an S5 you can tell by the 4 mounting holes where it would bolt up to the transmission.

The crossmember you need to use and the one you took off your car is an automatic one. Obviously the auto an manual xmembers are diff and you need to retain the member you were using to utilize those extensions for mounting. Next problem looks like you have a s5 auto xmember and a s4 trans and s4 y bracket. Your gonna need a s4 auto xmember. S5 ybracket bolts to the trans on the top of the y, hence less space between the rubber your trying to change. I'm guessing whoever did this never used the rubber blocks which are there for pitch and roll control.

Like I said, you need an S4 manual transmission crossmember to match your S4 y-bracket. The wider S4 bracket will not work with S5 crossmembers, which you can see from your problem.

Your latest pics are of an S5 crossmember and S5 y-bracket.

Ok, so I need to track down a automatic Series 4 crossmember. If I find a manual Series 4 crossmember would I be able to adapt my mounts to suit? Or are they a completely different shape?

And does anyone know where I can find a correct crossmember? Would like to buy one, but parts are a little hard to find in NZ.

I was just googling this mount and cam across this page. The crossmember they have shown here as a series 4 auto looks the same as mine.... Does anyone have an image of what i should have?

That's listed as an '86-'92 automatic crossmember, so it's S4 or S5. It appears that the same one was used for all years. Mazdatrix lists only one PN too: http://www.mazdatrix.com/g3.htm.

I think this would be the correct crossmember: http://www.atkinsrotary.com/store/pr...cat=680&page=1, but I do see a problem. The right side is angled, while the one you're using now is flat on both sides. This will create a problem with your custom conversion.

Ok, I have read about people doing auto to manual conversion on here without having many problems with the mounts. A lot of people just seem to make extensions like what have been used on my car, without having to worry about angles etc. I wonder why my car is different?

Does anyone have any pictures on how the manual series 4 mount sits in the transmission tunnel? Maybe I can modify my tunnel to do away with the extensions and mount it properly, would probably stiffen up my whole drive line as well.

Lots of conversion info in this thread: https://www.rx7club.com/showthread.p...02#post1919902. Post #15 shows an auto chassis with manual mount points welded in. You can see that one side is angled.

what i did was overkill because when i had done the swap 5 yrs ago now no one would chime in and I could not find any info on it.only after did someone spill the beans. either way itd done now. i dont really like what i made but it works. other tech difficulties are keeping me busy these days so why fix what works.

i did have a s4 trans then that motor blew so i rebuilt an s5 with s5 trans so i had to midify it to fit the s5 trans y monunt.

here is my cardomain page with the pics of what i did. it is on the first page http://www.cardomain.com/ride/2327466/1988-mazda-rx-7

Ok, right now you can not bolt that transmission to that crossmember.

How this swap would normally be done [as RotaryRocket linked] is that you would take that crossmember you have [which is from any automatic FC] and get an S5 Y-bracket and S5 [NA] transmission [or tailshaft]

So the question is, does the S5 Turbo transmission use the same Y-bracket as the S5 NA transmission. Looking at Mazdatrix's page, I believe that is the case. Assuming that is the case, then you need to: find an S5 Turbo trans/tailshaft+Y-bracket
or swap to NA parts [S5 Trans/S5 Y-bracket]
or weld in the manual crossmember body-side mounts and buy a manual crossmember
or fabricate some sort of custom transmission mounts.

Also, what was in there before?

The problem with this swap is that the auto trans, because of the overdrive has a longer tail shaft (where the driveshaft slides in), thus the mouting points are futher backward in the tranny tunnel. If you look at krazy karls pics from post #7 you will see the mounts on the tunnel are further back.

My trans bracket sits right under the original place of the S5 mounting points, in my case. I made it to fit between the frame rails. The pics dont show this but i had welded some small 6" long by 2" wide by 1/4" plates on the frame rails, to that I welded the mount directly to; it is in place for good.

I had got the idea to weld a removable one but havent had the chance to fab anything up. my inspiration came from an article in an old magazine of a F20C (s2k) swap in a miata.

The car was originally a factory Automatic Turbo. I got the manual gearbox swapped in soon after I brought it, the shop that did it cut a lot of corners and didn't really mount it properly. They were just using the center bolt in the y-bracket into the crossmember to hold everything together. This has over time slogged out and now means that I am getting a lot of noise and movement in the drivetrain. And yea the extensions are shown in the photos, they bring the mounting points back from the standard S4 auto position to the S4 manual length, they are both flat though.

Derekcat, I think you are right with your options. S5 stuff is a bit hard to come by here in New Zealand, and I need a turbo transmission not N/A. I think my best option would be to get some body side mounts and weld them in, I just don't know where the hell I could find some S4 manual ones. I have already started looking for wrecked shells in New Zealand but haven't found any yet. Do you know if it's possible to get them new?

Ahh okey.

Yea that will make sourcing parts the easiest. [Esp. since that center rubber mount can't be replaced, you have to buy a new crossmember..] I called my local Mazda dealer and the parts guy spent a couple days looking and got a hold of someone at Mazda North America who said that the part had been discontinued ~10years ago :/ So probably not going to be able to find them that way.
When I was thinking about cutting them out of a parts car, it looked like there might've been two parts to the manual body-side mount, compare pictures of your car's body to the parts car when you find one.

Also, it doesn't matter what manual car [S4/5] you get the mounts from, they're all the same on that way.

GoodLuck! ^_^

Aftermarket auto body to manual tranny
 

Www.xcessivemanufacturing.com has perfect mounts for converting automatic to manual.


https://cimg2.ibsrv.net/gimg/www.rx7...cdc1ec45e6.jpg