Ultimate IRS 8.8 Kit
1993-1998 Toyota Supra (MKIV)
The Ford 8.8 is a great bang for your buck rear end. It has many gear options available, which makes it not only very affordable, but also very flexible!
The Grannas Racing kit will allow you to install this strong, affordable rear end kit into your car with out any cutting or fabrication. The kit is 100% bolt in, and uses your factory rear subframe mounting holes. The mounting parts also come with a lifetime warranty! Like all our kits/parts, everything is designed by our founder, Joel Grannas, who is always looking to make the strongest AND best fitting parts!
The Grannas Racing 8.8 conversion kit utilizes our new HD Cast 8.8 differential cover. This cast aluminum cover is super strong and features main cap supporting load bolts, a breather port, a rear fill port, a side fill port, and drain port. The design of this rear cover allows the use of a bolt on mounting plate which allows the cover to adapted to the rear bolt pattern in your chassis.
The load bolts included with our cover provide support for the main bearing caps in the rear, for dramatically increased strength on hard acceleration. This is a very important part of these 8.8 rears when it comes to high horsepower applications.
This kit will work with multiple IRS 8.8 case types. The cast iron thunderbird is the strongest case! I recommend the iron case for cars making over 1000 HP.
The MKIV Kit will work with the following 8.8 IRS case types:
- Ford Explorer (2006.5-2010) "large aluminum case"
- Ford Thunderbird (1989-1997) "small cast iron case"
- Grannas Racing IRON reproduction case
- Mustang Cobra (2003-2004) or Lincoln MK8 (1993-1998) "small aluminum case"
The Grannas Advantage
What makes our kit the best out there?
GR Differential Cover
This kit uses the Grannas Ultimate 8.8 rear diff cover with load bolts for added strength. The cover is relatively low profile but has more fluid capacity that previous setups for better gear lubrication, better cooling and less fluid volatility.
Updated Casting Design
Our latest cover has a built-in inside baffle and an external breather port at 2 o'clock position for less "splash out"
Easier Maintenance
Easy maintenance - Two fill ports (back AND side) allows for much easier oil changes while diff is in car.
Quality Machine Work
Precision CNC machining - Our parts are all cut on CNC machines and will always seal tightly without leaks.
Cover Depth
Deeper bowl for big gear clearance. Previous cover setup had clearance issues with larger gears
Ease of Install
Unlike our old kit, which required a two step install process for the load bolts and girdle/cage setup, this new kit can be done in one step.
Level 5 / Direct Fit Axles (1000 HP)
These axles are designed to "bolt-in" and use the factory wheel hub on your car. There is no extra work involved other than removing the stock axles and installing these as a "direct fit". The outer hub is machined to accept the Supra ABS rings (you will reuse your OEM rings).
These axles have been engineered with fast street cars in mind that still occasionally visit the track for Drag, Road Course/Auto X duties. Designed to handle 800-1000 WHP depending on the application. These axles are made with some of the best 300M materials and heat treat processes in the industry.
Rated to 1000HP
Pro Level Axles (1400 HP)
These axles are designed to be used with the included billet wheel hubs and ARP extended wheel studs. These upgraded billet hubs have a larger spline size that will hold up better to hard launches and abuse. The Pro-Level Axle/Hub kit feature extra large 30 spline aerospace grade torsional axle bars, a direct-fit inner CV, and 108mm Porsche-style outer CV. The outer hub is machined to accept the Supra ABS rings (you will reuse your OEM rings). Designed for pro drag race use but is suitable for any streetcar.
You will need to purchase wheel bearings as new bearings are required when removing the OEM hubs. We do sell an optional rear wheel bearing kit for MKIV Supra/SC300 customers.
Rated to 1400HP
Need a differential with your kit?
Grannas Built Pumpkins
If you do not have a local shop near you to build your junkyard 8.8 we can help get you setup with a complete solution.
When you add our kit to the shopping cart, it will give you the option to add a built diff to the order. You will need to select the case type, the LSD type, and gear ratio and then click the add-to-cart button. See screenshot example on this page.
All our builds use all new bearings and seals. We also use a billet aluminum pinion shim instead of the weaker OEM crush collars that can fail under big power!
Gear Ratio Recommendations:
T56 Setups - 4.10
V160/V161 - 3.31
CD009 - 3.31
R154 - 3.55 or 3.73
Toyota A340 - 3.55
8HP - 3.31
TH400/powerglide - 3.31 or 3.55
I highly recommend using Ford Motorsports gears, as they are the quietest and most reliable ring and pinions. The Ford Motorsport ratios available are 3.31, 3.55, 3.73 and 4.10
Need all the rebuild parts?
If you have someone to build your 8.8 but need all the parts like the LSD/Spool, Ring & Pinion, and rebuild kit (bearings/seals), we sell all these parts separately.
Install Notes:
- Oil Capacity: 2 quarts
- I recommend Lucas brand 85-90 or 85-140 gear oil, but any quality gear oil is fine.
- If you are using a Detroit Truetrac or IRS 8.8 Spool setup, you do not need any special fluid/oil.
- If you are using a OS Giken LSD, ALWAYS use OS Giken differential fluid (2 quarts)
- Load bolts should only touch the back of the main caps with light pressure. DO NOT torque down the load bolt. After bolt touches cap, lock it in position with the nuts provided (15 ft lbs). Use silicon sealant on the threads to prevent seepage of gear oil.
- Beware of aftermarket rear poly subframe bushings. I have seen many of these companies making their bushings much thicker than OEM spec, which makes our rear stud hardware not fit correctly. I recommend PHR solid subframe bushings and PHR bushing install tool which are made to the same thickness as the OEM bushings.
- Breather Line: Use 1/4" inner diameter and 18" (or longer) silicone or rubber line with a loop in it tied up as high as possible in the chassis near the rear diff area. If you cannot get the line high enough or still experience splash out issues i recommend using our 8.8 catch can kit that allows oil to drain back into the diff to avoid fluid capacity dropping over time.
Specifications
| Axles | I do not need axles or LEVEL5 Direct Fit (bolt-in) or PRO Level with upgraded billet wheel hubs |
| Inner stub axles | I do not need inner axle stubs or Explorer Case Stubs or Thunderbird/Cobra/MK8 Case Stubs |
| Driveshaft - MKIV | No Driveshaft or Aluminum Magnum-F to Ford 8.8" IRS or Carbon Fiber Magnum-F to Ford 8.8" IRS or Aluminum CD009 to Ford 8.8" IRS or Carbon Fiber CD009 to Ford 8.8" IRS or Aluminum A340E (Auto Trans) to Ford 8.8" IRS or Carbon Fiber A340E (Auto Trans) to Ford 8.8" IRS or Aluminum V160/V161 to Ford 8.8" IRS or Carbon Fiber V160/V161 to Ford 8.8" IRS |
| Hardware | Thunderbird/Cobra Case Hardware Kit or Explorer Case Hardware Kit |