I own a 1992 Ford Fairmont V8 fitted with a BTR95LE Auto. The car at the moment is stock except for the 4 into 1 Extractors, Dual 2 1/4" exhaust (going back to a single 2 1/2" over the diff), 73mm MAF meter, K&N Air Filter & cold air intake, 17 x 8 EF Ticford Wheels fitted with 245x45x17 front & 255x40x17 back. I want to change my diff ratio in my BTR78 diff. It's currently 3.27 & I've heard that the nissans came out with 3.73 ratio in the manual & 3.9's in the auto and would fit. I would like to know which nissans are we talking about here. The newer GTS R33 or are we talking about the ones that came out with the VL motor's (the ones that have those stove like tail lights). Does anyone know how much does it cost to source the gears second hand & how much is it too fit them? How do I recalibrate the speedo? Do I have to buy an afftermarket chip or a converter that will correct the signal that is going into my speedo? Please help as any info will be appreciated?
Forget the Nissan gears, go for the genuine BTR sets, I did the following to my EB XR8 (man.) Prices quoted are for new parts so for used, work down from these, also it was done just before GST came in so the prices may vary a little.
New BTR 3.73 crown wheel & pinion set = $380, complete centre bearings, seals, spacers, pinion nut etc = $150, 1.8ltrs Castrol S.A.F.X.A. LSD synthetic oil = $27, some other things I needed but you may not: 2 axle bearing kits = $96, re-machine LSD case fit new cones(2) + side gears (2) + springs/shims to set to 240Nm. = $320, make sure the backlash & bearing preloads are set at 0.006. Labour cost $320. The speedo was out around 14km. It cost me an extra $200 to get it & the odometer recalibrated, only one place does this in Canberra so Iím sure itís cheaper elsewhere. If you go for a 3:45 there is small unit that they fit to fix the speedo ($25) but anything over that was a bit more work. Iíve heard Castlemaine rod shop were working on these sets for the other ratios. All the diff work was done by Boznjak engineering : Sydney Ė 9757 2133.
THERE'S NO REPLACEMENT FOR XR8 DISPLACEMENT
My car is very similar to yours with a mild 5.0 and auto tranny. I was also considering changing the ratio to 3.73s. If you are going to do it I would do what Ratman has suggested and buy a brand new BTR set. They come in 3.73 or 3.91. Price should be the same for either. I got quoted between $950 and $1,150 a couple of months ago to do the whole job.
In regards to your speedo I was told that either I'd have to get it recalibrated, which was from $100 to $300, or change the speedo gear in the tranny. The problem with this is that for a 3.73 you will need a 24 tooth gear, the highest one you can get from Ford is the black 23 tooth, which is for a 3.45. One speedo place I rang said that they can trim another tooth on the gear. All up to get the gear and trim it was about $50.
I'm a bit reluctant to do it at the moment due to a few people telling me that it will alter the characteristics of the car and being an auto it may not feel as torquey going too steep a gear.
I would like to know what difference it makes to changing the ratio to cars similar to ours with an auto. I gather it would probably cut 3 - 4/100ths over the quarter but what would it be like to drive on the road every day.
One other thing your MAF, what type is it, where did you get it from and how much did it set you back?
Ok I would like to say thanks everyone that has posted here. I have decided to go with the new parts instead of second hand. I am going to do the gear conversion probably in two weeks time so I will let you know how it went.
i've got a 73mm MAF which is also fitted to EB & EL GT & ED XR8 Sprint. I've bought it brand new form Coffey Ford in Melbourne/Dandenong for $195 about 1 1/2 to 2 years ago. There was 2 different prices listed for the MAF. One was $195 which came with the top part of the air cleaner box. On it's own the MAF was around $350+ (I can't remeber it exectly but it was much more then buying it with the top half of the air cleaner box). If you wanna buy it let us know because I might be able to get it cheaper because a friend of mine works there and gets about 30% off the Retail price.....
If you wanna buy it e-mail me on email@example.com & I will speak with my frined and tell you the price....
One thing with the 73mm MAF meter is that it is calibrated to 24lb injectors which were used in EB/EL GT's & ED Sprint so your car will flat spots at some rpm points . Try to get hold of the 24lb injectors as well if you can.
Evil EB my diff ratio is 3.27. All the ford V8's From EB - ED came with 3.27 with the exception of ED Sprint & EB GT Auto which came with 3.45. EF - EL Series I V8's came with 3.23 & Series II XR8 & EL GT came with 3.45. AU XR8's & Tickford T series models are using 3.45 at the moment & other V8 powerd falcons excluding those mentioned are using 3.08.
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