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What mount and crossmember for R154 into SC300? (have searched)

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Old 10-06-13, 10:12 PM   #16
KahnBB6
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Okay, I was only partly correct about this. You DO want this crossmember for your converted MKIII R154 box because it ALMOST fits the SC.

Everything lines up perfectly but the passenger side bolt holes on the SC chassis are still an inch or so farther away so the 82-85 Celica W58 crossmember has to be cut, extended about 2 inches (if I remember correctly) and welded. THEN it will fit the SC perfectly when using a stock MKIII Supra R154 trans mount.
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1993 SC300 5-speed NA | Built R154 | Gixxer_Drew Susp. 600/325 | TT: brakes FR, rims, rear sway, seats | Koyo rad | 4.272 TT Torsen LSD
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Old 10-08-13, 12:55 PM   #17
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Just use the stock SC crossmember , with W58 trans mount , everything bolt right up and you will not get any vibration.
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Old 10-08-13, 01:07 PM   #18
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Thanks but I already used the Celica crossmember with some extension and welding. All the bolts line up and the extension was the worst of it. I've seen what you're describing in pictures from other installs (notably Shern's) but I wasn't comfortable with it personally.

I have before and after comparison pictures I will post up. Obviously welding a small extension isn't "bolt-in" but it may benefit someone in the future.
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Old 10-08-13, 02:10 PM   #19
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Interesting modification, would have been really nice if the celica one fit without being extended.

Not trying to sound repetitive but since it requires cutting and rewelding I would re-consider using the stock crossmember or making a one piece solution. the celica mount is probably a hard steel you can weld good enough to, but something about having a extension performed on a very old factory cross member just doesn't seem like a structurally sound idea since those metals can fatigue over time and it looks well aged already. Not saying it won't hold but it seems risky.
If you modify the mount and it breaks, the crossmember will catch your trans and motor.
If you modify the crossmember and it breaks, that would be way worse and possibly devistating to the vehile and whoever is inside it, and it wont matter whether you re-drilled a hole or 2 on the mount or not.

the crossmember encounters lots of forces including vibrations, up and down, and side to side from turning and uneven roads, and I am sure the SC generates much more forces than the celica did.
Something to consider, a 1 piece solution is the right way to do it, or even a custom mount for the existing cross member. maybe you could reinforce the modified cross member with a solid piece welded underneath it. maybe I am just being paranoid on this one but the mount is much less important than the crossmember to the car as a whole.
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Old 10-08-13, 08:58 PM   #20
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Ali,

You bring up a good point but this is also how I feel about only connecting two bolts onto a transmission tail that was designed for four to be locked in place. Using the original crossmember there are two ways to do it: one involves using the W58 mount which only uses two bolt locations to secure the tailhousing instead of four as designed by Toyota in both versions of the R154. The second involves using a custom trans mount mount which adheres to all four bolt holes on the MK3 R154 tail but which requires using spacers of 1" or more depth to allow the modified SC crossmember to be the lowest point on the chassis.

Personally I don't trust either of those solutions as being better. My logic was to find a crossmember that Toyota designed that would have the closest possible fit and only change something if I had to. Strangely, we have seen someone use this mount or something very, very, very similar on an MK3 R154 into SC installation that DOES bolt right in with no welding. This must have been a mount designed for another RWD W-series or R-series application.

MKII Supra W58 crossmember may not have been over-engineered to endure the stresses of a turbo R154 but I do see some MKII Supra owners using that same mount to run R154 gearboxes.

You make a very sound argument. I can only offer pictures of what I have done. Here is a before and after. These guys at SpeedForSale who did this welding job for me (just quick, dirty and strong I might add, so not up to their usual standard of pretty looking welds) work on MKIV's, R34 and R35 GT-R's, FD RX-7's primarily so while I wasn't expecting perfection given the tight timeframe I gave them I do trust they wouldn't let me go with a bad set of welds that wouldn't hold up.

The reason I felt comfortable with them going ahead with it is that everything else including the angle the transmission was at if only one side of the mount was bolted in was exactly where it should have been. Were that not the case I'd have gone to Plan B: using the SC crossmember with the W58 mount.

Click the image to open in full size.

Click the image to open in full size.
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Last edited by KahnBB6; 10-08-13 at 09:02 PM..
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Old 10-09-13, 05:21 AM   #21
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I have done about 10 R154 swaps since 07 and never had any issues with the mount.

Both cars in my sig are on R154, plenty of HS pulls not a single issue with the mount or crossmember.

If I drive mine at 700whp everyday , I don't see why you will have an issue!!
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Old 10-09-13, 10:02 AM   #22
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what about using a marlin crawler trans mount, they look like they have the bolts in the same plane.
mostly everything they make is for thr w56 and r150 just happens to interchange a bunch.
It's possible the mount you are looking for in the same plane can be found on a 85-95 4 cylinder toyota pickup with EFI that came with a w56.

http://www.marlincrawler.com/armor/c...mber-mount-oem
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Last edited by Ali SC3; 10-09-13 at 10:06 AM..
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Old 10-09-13, 08:53 PM   #23
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Ali, I'll look into that. So you're saying MC's mount would work with the SC crossmember as a bolt-in solution?

First thing I am doing is installing the correct MKIII R154 front driveshaft in place of the SC300 Automatic front shaft I have in there now. That comes in Friday. I'm babying the car and not taking it over 3500rpm for now (maybe that's overkill but you can't be too safe). After that I will see about whether or not my crossmember solution needs to change.
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1993 SC300 5-speed NA | Built R154 | Gixxer_Drew Susp. 600/325 | TT: brakes FR, rims, rear sway, seats | Koyo rad | 4.272 TT Torsen LSD
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Last edited by KahnBB6; 08-09-14 at 01:44 AM.. Reason: Edited to denote which was incorrect driveshaft
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Old 10-10-13, 09:46 AM   #24
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Yeah it turned out nice, not sure if it needs to be changed but I agree the old solution with 2 bolt holes was not perfect, so maybe there is another mount out there that might work.
so the mount that trans came with wouldn't bolt to the crossmember?

I have no idea if the truck one will bolt in or not, or even work at all. I just know there are a few more flavors of the w series mount out there and I noticed the one for the trucks were not offset, but who knows where it will actually line up. I wouldn't pay almost 200 for a new one though on a hunch but to get one from a pick and pull or ebay might be worth the test.
My truck has a g54 box which is the 1 version prior to the w series but probably does have the same mount, I can take a look and maybe get some measurements or something, but its probably better to find one off a fuel injected truck.
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Old 08-09-14, 01:42 AM   #25
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I'm also in this same boat as I have an MKIII R154 with the parallel bolts and am attempting to swap in my auto SC. I did notice that my transmission actually has 3 parallel bolts (6 total) instead of the 2 on each side so perhaps there's a 3rd iteration of this transmission?

Click the image to open in full size.

Anyways, after searching on the web for various W58 threads across the Celica and Supra forums, I see that the W58 was used in early 198X Celica and Supras across different platforms. After ordering a few parts from Rock Auto earlier, I noticed they carried a transmission mount for the 1985 Celica GTS that looks very similar to the 2 hole variation of the MKIII R154 transmission. In theory, since our cars used the same type of transmission, the mount should in essence work with the auto or manual SC300 crossmember if the dimensions remained the same.

A very useful thread I came across discussed the similarities between all Toyota transmissions and even mentions my 6 bolt parallel version:

http://www.toymods.org.au/forums/tec...box-mount.html

Here's the transmission mount:

Click the image to open in full size.

http://www.rockauto.com/getimage/get...A1040825-1.jpg

I don't know if the dimensions for the holes on the crossmember are the same but at the price of under $20, I figured I'd give it a shot and help out the community in the process. I'll report my findings and share it with you guys. Sorry for bringing back an old thread but it's useful stuff!
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Old 08-09-14, 02:00 AM   #26
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^^ Kire, everything you have stated above is true and the 1982-85 Celica W58 crossmember solution is exactly what you will find I did (refer to page 1 of this thread). Installation is covered on post #22 on this page.

The thing is, it's very, very close to being a perfect solution, and it CAN be used but it isn't bolt-in. It requires cutting and welding.

There may be another crossmember that bolts into the SC chassis holes *directly*, possibly from a Toyota truck with a W56 (I highly doubt it though) but with the 82-85 Celica W58 crossmember you will find it bolts to the transmission correctly and bolts to the driver's side chassis holes but NOT to the passenger side holes because it is too short on that side.

The solution (Post #22) is to cut and weld in new plate steel (I can't remember the specific length, sorry) and reinforce the hell out of those welds. I didn't do it myself. I had a Supra specialist shop do it for me.

It's absolutely good information for the community. Unfortunately there still is no perfect solution when bolting up an MKIII R154 in an SC but this crossmember is a very close one.

As for the three bolt holes on the rear tail housing of the MKIII R154, I have the same three on each side of mine and I suspected this was for any other JDM vehicle Toyota sold in the late 1980's with a 7MGTE 5-speed or 1JZGTE 5-speed such as Chasers, Crestas and Mark II's.
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Old 08-09-14, 02:12 AM   #27
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Quote:
Originally Posted by KahnBB6 View Post

There may be another crossmember that bolts into the SC chassis holes *directly*, possibly from a Toyota truck with a W56 (I highly doubt it though) but with the 82-85 Celica W58 crossmember you will find it bolts to the transmission correctly and bolts to the driver's side chassis holes but NOT to the passenger side holes because it is too short on that side.
Thank you Kahn! What I'm trying to see is if the mount itself from the Celica will hook up to the transmission and stock SC300 crossmember since they both used a W58 of some sort. Like I said, in theory it sounds like it should work but I won't know until I try it with the mount. I don't believe anyone has tried this yet so it's worth experimenting. I'm really hoping it does so we have an alternative to the DM kit or the 2 bolt hookup that Shern did a while back.
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Old 08-09-14, 02:20 AM   #28
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Oh! I completely forgot to mention the transmission MOUNT (not crossmember). Yes, it will work That's what I did and that was my reason for seeking out the Celica W58 crossmember. The transmission mount is the easy part of this.

Other than rubber formulation for more torque possibly being different for the turbo car vs the NA car it's roughly the same rubber mount with four studs that extend into the crossmember. This preserves your clearance under the car.

Just get an OEM 1986.5-1992 Supra Turbo 5-speed (R154) transmission mount from a dealer or DM.

Read through this thread from page one and you'll see.

Now the issue with the Celica crossmember being your best bet but still requiring cutting, plate steel extension and welding... that still stands from my post(s) above. Also, you're not going to be happy when I tell you Toyota has long since discontinued the 82-85 W58 Celica crossmember. You can't order that from a dealer-- I had them look it up and verify that. You just have to find one. I picked one up on ebay for $75 and took it to a shop that media blasts and repaints chassis parts to restore it before installation (before I realized it had to be extended).

For some, the DM crossmember solution may be a more attractive option since you can actually just bolt it in. But then there is the additional 1-1.5" lower everything sits. I don't understand why they didn't design it around the OEM MKIII transmission mount and figure out how to machine or stamp a recessed area for the four studs to go into as with the OEM the Celica and Supra mounts. Don't get me wrong though, Aaron and Co. make some really great stuff at DM to facilitate a lot of these popular swaps. I just like the idea of using OEM parts and solutions whenever possible.
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1993 SC300 5-speed NA | Built R154 | Gixxer_Drew Susp. 600/325 | TT: brakes FR, rims, rear sway, seats | Koyo rad | 4.272 TT Torsen LSD
------------------------

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Old 08-15-14, 09:18 AM   #29
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I just received the transmission mount from Autozone on the 85 Celica and after a quick glance and measurement, the mount ALMOST fits my stock SC300 aluminum crossmember but appears to be a perfect fit on the R154 itself! The 4 holes that go to the crossmember are a tad short on the mount but I think I can make these a little bigger with a dremel tool and make it work. This would make it a tad bit safer than the method of only using the two bolts on the W58 mount so I'll share my results as soon as we find out after work!
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Old 08-15-14, 11:03 AM   #30
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^^ Are you also going to bore out a big hole or recess in the center for the metal center bolt on the MKIII Supra (or Celica W58) mount to rest into? I've heard of this being tried but I haven't seen it done successfully. I'd like to see pictures of what you're trying but unless the big center bolt has a lowered area to rest into I'm not sure. Or perhaps does the Celica W58 mount not have that center bolt while the MKIII mount does?
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Old 08-15-14, 11:03 AM
 
 
 
 
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