We had a customer s
top in and ask if we could install a Quaife limited slip differential into his 2007 Jag XK-R. He was tired of the 1-tire-fire problems and wanted an LSD to help keep the power to the ground with both wheels. Due to the fact that we are a dealer for Quaife, we had them send us a unit. Here are some details of the Quaife upgrade below along with a much needed drain plug install.
UPDATE: We would like to also note that we are very familiar with the late model Jag rear differentials. Any part you need, and any gear ratio you want, we would be more than happy to build the unit for you! We can rebuild any Jag diff no matter what the failure or upgrade. Gears, bearings, diff parts, seals, and case pieces are available through us. Please email for details!
We ordered the Quaife diff and had the customer drop the vehicle off at our Jacks Transmissions Service Center.
Pulling the differential out of the vehicle was simple. We disconnected the drive shaft from the diff, removed the exhaust, removed the passenger side CV by unbolting a few suspension components on the passenger side, unbolted the diff from the subframe, and then simply popped the driver side CV out of the diff while pulling it down and out of the vehicle. Due the fact that this rear diff does not have a drain plug, fluid spilled out of the open CV seals as we lowered the unit, but that problem will be fixed shortly:
This unit is a little different than your typical assembly as it only had a cap on the left side and a retaining clip on the right. The seal on the right side had to be removed in order to gain access to the clip. Once the clip was removed, we removed the cap and were able to pull the OEM open diff out of the assembly.
| Once removed we found the OEM bearings are not available for this unit from the dealer or our bearing supplier. Jag says you have to purchase the whole rear diff assembly in order to get new bearings, which is not acceptable. We noticed that the bearings looked to be in perfect condition, so we carefully removed them from the old diff assembly. One side was easy, but the other had no way to grab the bearing safely, so we ended up cutting the end of the old diff off so we had easy access to the bearing. UPDATE: we now have access to the bearings, so no need to go through what we did in here. New bearings can now be installed! |
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Picture of the cut OEM open diff on the left and Quaife, with successful bearing swap, on the right.
We cleaned the unit and bolted the ring gear to the Quaife, installed Quaife into diff housing, installed right side clip, and checked bearing preloads. The preloads were perfect! We then checked the gear contact patch and it was also perfect! UPDATE: we can get just about any gear ratio you wish for this differential now also. Gears too short? Not a problem!
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Now that the diff was out of the car, we thought this would be a good opportunity to install a fluid drain plug as a courtesy to the customer, so rear end fluid changes could be possible. Why Jag didn't install a drain plug doesn't make sense, but at only 40k original miles on this car, the original fluid was burned and in very poor condition.
We decided to install the drain plug in the aluminum end cover as this would allow for easy access and prevent any road debris from hitting the plug. This is slightly higher than the lowest point of the sump, but over 90% of the fluid will still be drained. This is better than nothing at all!
We used a 1/8" NPT allen head plug as it is small and easy to remove. Install was simple. We drilled a hole, tapped it and installed the plug. So easy and very highly recommended if you are going to run an LSD!
Buttoned everything back up:
We appreciate this opportunity and would like to say THANKS to the customer for choosing us. The customer also had a note which we will share:
"I can thank Jack and everyone at Jack’s Transmissions for the first rate job they did in making all this possible. They overcame obstacles, which were to be expected during a first time installation in the USA, and proved to be innovative and imaginative in developing solutions to difficult problems with no help or previous experience to rely on. They went out of their way to solve a problem related to a servicing issue which has enabled me to ensure proper maintenance of the new LSD. No one would ever have noticed the problem with the lack of a drain plug if they hadn’t brought it to my attention. It’s that kind of attention to detail and professionalism that makes me really happy I took my car there. They proved to me beyond a shadow of a doubt that they are the turn-to guys when it comes to working on any kind of car imaginable. And that includes the most exotic performance cars on the planet.
By the way, it should be noted that Jack is not only a master mechanic; he’s an extremely talented writer and photographer as well. Most of the content of this stage of the upgrade was written by Jack himself. All I had to do was integrate his writing and photos into the format of the article. Thanks Jack!"