Can you use this diff?
you could mount anything in there with enough fabrication, here is a ki that uses the ford 8.8. which is stronger than the shitty 10 bolt anyway.
http://www.bossfrog.biz/Miata_V8_Swap.html
http://www.bossfrog.biz/Miata_V8_Swap.html
No reason you can't use any rear diff.. as long as it can be shorten in width and mounts can be alled. Soif you can get the F-Body one setup.. go for it..
But as stated above.. they are pretty weak and there are better choices. One plus is that the Miata is a lot lighter and will help it live under the V8 power/torque.
From what I have read.. most Miata go with the Ford 8.8 as it fits well and is more that strong enough that you can throw just about anything at it.
if going with the F-Body..Another option is to try and find one of the third generation Camaros that were available with an optional Borg Warner 9-Bolt rear end. And much stronger that the 10 bolt GM ones. But can be hard to find and cost more to find parts to rebuild. A plus is that the 3rd gen are a 1" narrower on each side. But will use the same mounting points and hardware.
But as stated above.. they are pretty weak and there are better choices. One plus is that the Miata is a lot lighter and will help it live under the V8 power/torque.
From what I have read.. most Miata go with the Ford 8.8 as it fits well and is more that strong enough that you can throw just about anything at it.
if going with the F-Body..Another option is to try and find one of the third generation Camaros that were available with an optional Borg Warner 9-Bolt rear end. And much stronger that the 10 bolt GM ones. But can be hard to find and cost more to find parts to rebuild. A plus is that the 3rd gen are a 1" narrower on each side. But will use the same mounting points and hardware.
If doing the swap, I'd probably go with the 8.8. Everything I heard about the 10-bolt 7.5" gives me the impression it is a ticking time bomb. If you REALLY want to use a 10-bolt and have mad narrowing skillz, go with one from a 90s B-body (Impala SS, Taxi cab, Roadmaster, etc). They've got 8.5" ring gears, 30 spline axles and coil spring mounting. Some have rear disc.
I have a N.O.S. factory posi diff unit for one, with new bearings pressed on, that I'll let go for stupid cheap (ended up using a truetrac instead). It will also fit a 2nd gen F-body diff, but will require new axles.
I have a N.O.S. factory posi diff unit for one, with new bearings pressed on, that I'll let go for stupid cheap (ended up using a truetrac instead). It will also fit a 2nd gen F-body diff, but will require new axles.
With a welder, a torch, and a lot of time, you could probably do just about anything. But why would you?
The Miata is an IRS car. And there are a couple of complete kits available to use a very strong IRS unit. IMO, a small car like a Miata really does a lot better wit IRS. The ride and handling is vastly superior.
The only real reason to use a solid axle is if the car is specifically set up for high horsepower drag racing. And then you'd probably want to put in a rear sub frame from Reher Morrison, and an aftermarket Ford 9" diff.
The Miata is an IRS car. And there are a couple of complete kits available to use a very strong IRS unit. IMO, a small car like a Miata really does a lot better wit IRS. The ride and handling is vastly superior.
The only real reason to use a solid axle is if the car is specifically set up for high horsepower drag racing. And then you'd probably want to put in a rear sub frame from Reher Morrison, and an aftermarket Ford 9" diff.
Thread Starter
Teching In
Joined: Dec 2008
Posts: 10
Likes: 0
At the time of the post I was not aware that the miata was a IRS.
s the ford the only diff you guys would suggest? are the CTS IRS as good as the ford 8.8? I am looking for something with 3.42 gears already in it.
s the ford the only diff you guys would suggest? are the CTS IRS as good as the ford 8.8? I am looking for something with 3.42 gears already in it.
Same here.
I'd look into what .boB is saying. I know there are a LOT of go fast parts geared toward Spec Miata racing, and I wouldn't be surprised to find something beefy enough to take LS1 abuse. If not, the 9 inch is a winner and the 8.8 will do the job.
If you're hell bent on swapping out the original rear suspension, some IRS donors that might be worth looking into include late 90s BMW 3-series and 4th gen Mustang Cobra. I'm guessing the CTS suspension will be too big to realistically modify and have fit correctly in a Miata. You might have an Indy car look on the rear end.
I'd look into what .boB is saying. I know there are a LOT of go fast parts geared toward Spec Miata racing, and I wouldn't be surprised to find something beefy enough to take LS1 abuse. If not, the 9 inch is a winner and the 8.8 will do the job.
If you're hell bent on swapping out the original rear suspension, some IRS donors that might be worth looking into include late 90s BMW 3-series and 4th gen Mustang Cobra. I'm guessing the CTS suspension will be too big to realistically modify and have fit correctly in a Miata. You might have an Indy car look on the rear end.
Trending Topics
Thread Starter
Teching In
Joined: Dec 2008
Posts: 10
Likes: 0
Well I am not really "hell bent" on anything yet. I am just trying to find out which is the best one to use and if I can get it with 3.42 gears, otherwise I'll have to tune my car to get the correct mph.
Which kit should I use for the ls1 miata build?
Which kit should I use for the ls1 miata build?
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Five Reasons the Camaro Was the Most Pivotal Player in the Pony Car Wars 2.0
Brett Foote
10 Reasons the LS7 Is GM's Most Extreme Naturally Aspirated V8 Engine Ever
Verdad Gallardo
Ford makes a zillion gear ratio choices. Stock '03-04 Cobra rear is 31 spline LSD and 3:55 gears. The Tbird is 28 spline and typically taller gearing (3.08 etc) and non LSD.
The Driveshaft Shop can build you axles in any config you want. Remember you are going to have $2K wrapped up in the rear end easily alone upgrading to the 8.8" IRS setup and DSS axles plus upgraded dshaft.
Problem with Miatas and big power... is you can't put a ton of tire under them unless you run flared fenders.... and they have a pretty short wheelbase. They can be made to be very very light though and can haul *ss.
The Driveshaft Shop can build you axles in any config you want. Remember you are going to have $2K wrapped up in the rear end easily alone upgrading to the 8.8" IRS setup and DSS axles plus upgraded dshaft.
Problem with Miatas and big power... is you can't put a ton of tire under them unless you run flared fenders.... and they have a pretty short wheelbase. They can be made to be very very light though and can haul *ss.
There are two readily available options: Ford 8.8, and Getrag (from GM). The Getrag is readily available, and allows the use of 3" twin tail pipes. But there have been some problems with leakage (not breakage).
The Ford 8.8 comes out of a T-bird or Mustang IRS. It is a lot stronger than the Getrag, and will handle just about anything you can throw at it. But it is heavier and bulkier; and only allows the use of 2.75" tail pipes.
http://www.flyinmiata.com/index.php?...002%20%208.8S3
http://www.bossfrog.biz/Miata_V8_Swap.html
The Ford 8.8 comes out of a T-bird or Mustang IRS. It is a lot stronger than the Getrag, and will handle just about anything you can throw at it. But it is heavier and bulkier; and only allows the use of 2.75" tail pipes.
http://www.flyinmiata.com/index.php?...002%20%208.8S3
http://www.bossfrog.biz/Miata_V8_Swap.html
