LSX/T5: The Final Word - Ford Mustang Forums : Mustang Forum
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post #1 of 5 Old 06-11-2014, 10:04 PM Thread Starter
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LSX/T5: The Final Word

Invariably many mustang owners ask whether it is possible to use a T5 5-speed transmission with a LSX motor (e.g. 4.8, 5.3, 6.0, LS1, LS2, etc.). Typically these individuals already have T5s and are looking to cut down on the cost of the swap. While I have not carried out this swap, I have conducted substantial research and feel compelled to share it with everyone in a single location (so people are not forced to scour the web like I had to).

Is this swap possible? Answer: Yes. But these are all Frankenstein builds, typically requiring a mixture of GM and Ford parts.

For starters, World Class T5s are the only model that should be considered. Whatever option is chosen will require the use of a fox-body tailhousing though (perhaps a 94-98 tailhousing would work too).

The T5 transmissions in order of preference for this swap are:
  1. 89-92 GM Third-gen F-Body T5 from a V8 with a 2.95 first gear (hard to find and can cost between $600-$1500);
  2. 96-02 GM Fourth-gen F-Body T5 from a 3800 V6 with a 3.35 first gear (can often be found for less than $300);
  3. 90-95 Ford Mustang T5 from a V8 (the T5z with the 2.95 first gear being the ideal candidate); and
  4. 99-04 Ford Mustang T5 from a V6 (can be had for as little as $100).

All of these WC T5s are rated at between 300-330 ft/lbs, depending on the model. The GM units that are listed have 26 spline input shafts that allow for the use of LSX clutches – something to keep in mind. The 10 spline input shaft of the Ford T5s require a custom clutch setup and other adaptations. For this reason, the GM T5s are a better starting point than the Ford T5s. Many thirdgen F-body drivers have managed to keep their 2.95 T5s alive behind 350 small blocks with conservative driving; so that should provide some piece of mind.

Option 1: The Third-gen F-body T5

This transmission has a standard muncie bolt pattern on the front of the case, allowing for the use of various chevy bellhousings. This is by far the easiest option, but these transmissions are increasingly difficult to find (a good resource is Ebay or

Necessary Parts:
  1. Bell Housing: GM ‘621’ or equivalent
  2. Pilot bearing: LS7 style, GM part # 12557583
  3. Flywheel and Clutch: standard LS1/LS6/LS7/etc.

The 621 bellhousing is intended for Big-Block chevys, and it is large enough to hold the LSX 11” flywheel and clutch. A SBC bellhousing is too small. The bottom two mounting bolts on the T5 case will need to be resized to allow the 621 to bolt up to the GM T5 case. After swapping on a fox-body T5 tailhousing you are set to go.

Option 2: The Fourth-gen F-body T5

This transmission is an unusual hybrid. It has a GM 26 spline input shaft with a traditional 4.680 inch main drive-gear bearing retainer-to-bell-housing pilot hold dimension; but a minor problem is that the input shaft is approximately 5/8ths of an inch longer than the third-gen. The Third-gen input shaft (as measured from trans case face to input shaft tip) is 6.71 inches, and the Fourth-gen's input shaft is 7.17 inches long.

The next issue is that the fourth-gen T5s use Ford T5 cases (the bottom 2 mounting bolts measure 6 3/8 inches apart instead of the usual 9 ¼ inches). The likely reason for this is to cut down on production costs.

Thankfully two solutions arose with an aftermarket bell. Originally there were two conversion bells that were available from the aftermarket:
  1. The Quicktime/Lakewood RM-6037 bell; and
  2. The McLeod Racing Modular bell.

McLeod discontinued their modular LSX-T5 bell kit (a combination of components) a couple of years ago, but a custom kit can be assembled. In the February 2008 issue of Hotrod Magazine, the following components were listed for creating the necessary 7.337 inch stack height for using a fourth-gen T5 with a SBC:
  1. Bellhousing kit (Part No. 8710-00);
  2. Spacer Plate (Part No. 8703-14);
  3. Cap (Part No. 8702-0);
  4. Choke Ring (Part No. 8701-4)
  5. Dowel Pins (Part No. 8707); and
  6. Dowel Pin Set (Part No. 87080200).

At this stack height, the input shaft tip ends up 0.167 farther back than the theoretical blueprint depth, and a standard chevy pilot bearing can be used. The “Cap” will need to be drilled to fit the bolt pattern on the Ford case. Please call McLeod to confirm that the bellhousing kit specified will be compatible with your LSX. The bellhousing itself should have a stack height of 5.500” and the motor plate should have a stack height of 0.187”.

A more straightforward swap would involve using the Quicktime RM-6037 bellhousing that is still widely available. Vorshlag motorsports used this bellhousing in their T5/LSX swap into an E30 BMW to great effect. They were also able to use an off-the-shelf LS6 flywheel and clutch with this setup, but it required the use of an extra long 1.012” pilot bushing (available through speedway motors).

Specificaitons for RM-6037 - LSX Bellhousing to Ford T5 Mustang Transmission
Height = 6.925
Trans. Bore Ø = Universal 4.850/4.910 (looks like it has an adapter ring included)
Engine = Chevy LS-1, LS-2, LS-3, LS-6, LS-7, LS-9
Trans. = Ford TKO 500-600, TR3550, T5 Mustang/Jerico 4-5 Speed
Clutch Ø = 11"
Flywheel = 168 tooth or 153 tooth (LSx flywheels are usually 168)
Weight = 22#
Full engine plate, trans ball and grade 8 bolts included
SFI Certified @ 6.1

Another Option: A blank T5 adapter plate from Mcleod is available (Part#: 673-8607B)

It could be machined to adapt the 96+ Camaro-Ford case to a 621 bellhousing. At the proper width, it would also offset the extra length of the 96+ 26 spline input shaft.

Options 3&4: The Ford T5s

These methods are similar to using a fourth-gen GM T5, but require additional work due to the Ford 10 spline input shaft. There are a couple of miatas running this setup, but I have had no luck contacting these individuals. A company called V8Roadsters supposedly has the Ford T5 to LSX swap worked out.

The following components are necessary (in addition to the RM-6037 bellhousing):
  1. Ford T-5 to Chevy adapter Pilot Bearing (Lakewood Part #15975);
  2. ls1 flywheel;
  3. ls1 pressure plate; and
  4. 11" ford 10 spline clutch disk from 2000-up gt mustang.

Note: Call Lakewood to confirm compatibility; and also matching up the right plate and clutch disk will necessitate some level of trial and error (Google is your friend here).

Also, a company called Wilcap supposedly makes an adapter kit for the Ford T5 to LSX (Part# BHA-350-FT5).

Elusive Options: There are rare bellhousings from a 4.3 Ford Astro van and possibly one from an AMC car that could work. Tracking these parts down have proven next to impossible by most that have tried. Stick to aftermarket options.

Summary: GM T5s are far easier to use with an LSX than a Ford T5s since they have a GM input shaft. A Ford tailhousing can (and should) be swapped on to the GM T5 to run the speedo cable and allow the use of Mustang T5 shifters. If shifted politely, a WC T5 should hold up well behind a stock 4.8 or 5.3 lsx motor. As with the 5.0, if you abuse it you will break it. Vorshlag's lightweight E30 LSX BMW broke more than one transmission drag racing if I remember correctly. Keep this in mind. With the T5-LSX combination, a hydraulic clutch conversion is probably necessary. Numerous parts are now available on the aftermarket (Howe Racing, McLeod, etc.); and some mix-and-matching might be necessary to make everything work. A few details have been left out here-and-there, but this thread should give everyone a solid start.

Best of Luck.

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post #2 of 5 Old 06-11-2014, 10:26 PM
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a lot of bull#### to go thru for a tranny that won't hold the power anyways

Originally Posted by Wicked03GT View Post
The internals may support 800HP, but that block will spilt faster than a virgin on prom night!
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post #3 of 5 Old 06-12-2014, 04:35 AM
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Nice write up,
For all that i would just go t56 and get it over with.

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93 coupe 427tt, t56, Big Brakes, UPR suspension, RSV custom wheels, Carbon fiber.
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post #4 of 5 Old 06-13-2014, 01:50 AM
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Very nice write up sir!
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post #5 of 5 Old 06-13-2014, 08:47 AM
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good write up but now with the T56 a much strong trans and being more available in yards the prices are coming down. the article in 08, prices where still high. I hate to admit what I paid for a 98 LS1 motor back in 06 for my Mustang. To now I bought a 30,000 mile 6.0 alum motor for the 3rd of the price.

93 Coupe, Reef Blue, a/c, 3:55's, 10 holes,
1/8 6.56 @ 103.23 mph, 1/4 10.37 @ 128.49 mph 1.43 6/06/15
1/8 Nos 6.06 @ 114.71 mph 1.38 12/16/15
1/4 Nos 9.879 @ 135.29 mph 1.39 12/19/15
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