Supra Diff Install with pictures

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mopman93
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Supra Diff Install with pictures

Post by mopman93 » Fri Apr 01, 2016 8:01 pm

I've been working on putting my supra diff conversion in and there's not much in the way of centralized information on this swap. I'll try to put together what I can here.

- 4.30 ratio open diff I believe out of an automatic
- JVAB diff kit, this is the kit that requires new holes drilled in the trunk area for extra support
- Supra mounting flange, u-joint and weld yoke. These parts were sourced from powertrainindustries.com

(1) Okay, so very straight forward. Remove driveshaft and old diff. I left the axles in the car and just tied them up to the sway bar. I did not remove the sway bar for this swap.

(2) Bolt the two lower brackets to the subframe, make them finger tight. When you go to install the diff you want a little bit of wiggle room in these brackets but if the bolts are too far backed out, they will contact the diff during installation.

(3) I took the rear diff mount and loosely bolted it to the car, the bolts holes are slotted and the bracket should be placed as far rearward as possible.
NOTE: the mounting bosses on the diff cover are different heights. The taller one must be machined down to match the lower one. I had the guy at the driveshaft shop take it down for free. JVAB also offers pre-machined covers on an exchange basis if you so desire.

(4) Bolt in the diff. Its a heavy mother. Don't hurt yourself. Two bolts in the rear through the diff mount and then two bolts up front with the machined spacers.

(5) Once everything was in and tightened up I set about drilling the trunk area for the additional supports. 4 bolts with weld nuts are supplied with the kit, I only used two because as you will see in the pictures the other two nuts need to be machined to fit inside the frame channel. I don't forsee this being a problem. You must use at least two. Forgoing this step and relying only on the small bolts from the factory mounts will most likely rip out. Center punch the holes, and drill them out. Then cut small access holes in the trunk floor and fish the weld nut in from above. It's very easy. Took me about 10 minutes to do both.

(6) Once the secondary mounts are installed you can bolt on the cv adapters. I used a small amount of hylomar to seal them to the drive flanges. You will need the 14mm hex nuts from the supra diff, the mounting face for the cv joints is as close as possible to the nuts. I had to use a crescent wrench to tighten them up. I would imagine that ARP style 12 point nuts for head studs would be a good application for this.

(7) Bolt up your axles install your new driveshaft and enjoy.

Comments:
(1) The cv adapters are dual drilled for the factory cv's and the cossie cv's. When you bolt up the factory cv's they do not completely cover the cosworth bolt pattern. I imagine some grease will come out of these holes. A solution would be to get the press in caps for the inside of the cv's that come on most newer axles.

(2) The driver side lower bracket needs to be trimmed to fit. The flange on the beam bends out at about 30 degrees and the bracket needs to be relieved around it. Takes a minute with a hacksaw or whatever.

(3) I used a 1351-20 u-joint for the supra flange. The spicer number is 5-1510X. The weld yoke is 1326-20. These are powertrainindustries part numbers. I imagine the weld yoke will need to be machined to fit the driveshaft. Both pieces were $50. The overall length of the driveshaft will not change.

(4) I will have to clearance my exhaust for the diff to fit. It mounts below and to the outside of the beam flange so depending on how close your exhaust comes to your beam you may have clearance issues.

(5) I was able to keep all 4 bolts in the original diff mount location. I put them all in for piece of mind. Do what you will.

(6) I have seen kits that include a piece for the upper mounting location in the beam. The kit I purchased did not have this piece. I may fab something up later to pick up this point, but my car is about 160 hp NA so I'm not worried about it currently.

Here are the pictures.

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Choochoochoo
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Re: Supra Diff Install with pictures

Post by Choochoochoo » Fri Apr 01, 2016 9:06 pm

Other than different gearing options, what's the point in the supra diff swap?
2000 Dodge Durango 5.9 (gone, and missed)
2008 Mercedes Benz R320CDI
1985 Merkur XR4Ti

timxr8
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Re: Supra Diff Install with pictures

Post by timxr8 » Fri Apr 01, 2016 10:14 pm

Choochoochoo wrote:Other than different gearing options, what's the point in the supra diff swap?
Stronger, better LSD if you get that option, cheaper, source parts in the US....sure there's more reasons.
Tim Spencer
1988 XR4Ti Duratec project car
2011 Taurus SHO daily driver...not stock.

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mopman93
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Re: Supra Diff Install with pictures

Post by mopman93 » Mon Apr 04, 2016 12:41 pm

Heard from the driveshaft shop today, the inside diameter of the rear portion of the driveshaft is 1.866"

espacef1fan
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Re: Supra Diff Install with pictures

Post by espacef1fan » Mon Apr 04, 2016 11:08 pm

I used a bead of rtv on flange and cossie bolt holes to seal in grease
Adam Escott
Dothan, AL
89 XR with Outcast Body in red
Duratec build in progress(need cams and stand-alone)

espacef1fan
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Re: Supra Diff Install with pictures

Post by espacef1fan » Mon Apr 04, 2016 11:10 pm

I do find it curious the rear diff mount hangs off of the edge of the frame rail though. Both my cars it have the same issue. I wonder why JVAB designed it that way? I tried instaling it by turning it around and it was even worse :/
Adam Escott
Dothan, AL
89 XR with Outcast Body in red
Duratec build in progress(need cams and stand-alone)

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mopman93
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Re: Supra Diff Install with pictures

Post by mopman93 » Tue Apr 05, 2016 1:50 pm

Yeah, Idk about the overhang, doesn't bother me for now.

I will be doing the rtv as well, seems like a good enough solution.

I have to say after driving with the new diff the car is much more enjoyable. Most of it can be attributed to switching from 3.36's to 4.30's but since this was made possible by the supra diff, ill give it all the credit.

I have a 0.80 overdrive, with a 24.3" tire and 4.30 gears my 5th gear at 70 is just under 3400. This works nicely with the N/A 2.0 duratec.

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xrattiracer
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Re: Supra Diff Install with pictures

Post by xrattiracer » Tue Apr 05, 2016 3:55 pm

the rear mount is still worked on a bit (when i have time to work with John, buying a house takes up sooo much time).
one recommendation i would give is to make sure to do hard poly bushes (or even better, solid mount) on the two main beam mounting points. if the beam can move around at all, it will put too much stress on that rear mount and it WILL rip the bolts out.
86 Silver XR4Ti. 'squirted. 12.7@111
03 VW Golf tdi
05 Yamaha FZ6

ossie cossie
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Re: Supra Diff Install with pictures

Post by ossie cossie » Fri May 13, 2016 8:14 am

1st post, Good work, i am from Australia and am putting a supra diff in my track car cosworth, is there someone on here that can make the drive shaft adapters or does anyone want to sell a pair. Thanks

John V
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Re: Supra Diff Install with pictures

Post by John V » Wed May 18, 2016 6:58 pm

ossie cossie wrote:1st post, Good work, i am from Australia and am putting a supra diff in my track car cosworth, is there someone on here that can make the drive shaft adapters or does anyone want to sell a pair. Thanks
G'day, Fred..reckon you might try the guy who makes these kits..
Right ornery bastid according to all the kiddies.. But makes remembering the company name eaiser

Its JVAB and it actually stands for John Van Awful Bastid...I hear there were 2 drunken Swedes, a lotta mouse piss beer and a swimming pool involved but easy to remember
Google JVAB in Sleezattle WA---not Western Australia silly bogan! WA is WAshington state in Fortress America™

That'll take ya to a site full of all kinds of purdy piccies and the address and email is there...
If you ask nicely he can probably supply the flang yokes and the weld yokes for the propshaft...

One note. He rarely looks in on here, and he hates PMs cause ya gotta delete them all the time so direct email or phone.

He speaks a couple of dialects of Engrish, swears like an Irishman but makes good stuff---like brakes and suspension more or less modernised and easier but like Group A stuff...Like 1.25" x 282mm front disc and bells and 11.75" x .81" rears, and nice caliper carriers modeled off early Group A ones when they were still using modded and strengthened standard steel rear arms..

I know he has a pile of adapters, saw at least 20 like 15 minutes ago.
John Vanlandingham
Sleezattle WA USA
CALL =-> (206) 431-9696 <-= CALL

http://www.rallyrace.net/jvab/

ossie cossie
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Re: Supra Diff Install with pictures

Post by ossie cossie » Sat May 21, 2016 7:43 am

Thanks i have sent an email. :D

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