Chuck's Jaguar D Type Build

Jag Lovers is an excellent site also.I did a 62 etype and found that site invaluable. Lots of great archives and Jag lovers eager to help.There were also a couple of Dtypes being built and a couple finished and driven.LOTS of Jag knowledge.

If it were me Id use both sites.Keep your friends here and make some new ones.Im sure they would be glad to see you there also. Thanks DJ


GT40s Supporter
Thanks for the tip DJ. I will check it out.

I started a parallel blog at, but quickly reached a limit on the number of pictures that could be posted. That limitation made use of the forum untenable. Unfortunate, really, since there were some pretty good folks frequenting the site.
This is a fantastic thread, and I love D-types almost as much as GT40s. But since it’s an RCR car, why not put it in the dedicated RCR forum, along with the other oh-so-cool products Fran makes?


GT40s Supporter
Rear Suspension, Part III, Secondary A Frame

The primary A arm on the original D Type provided lateral alignment of the rear suspension. RCR uses an A Frame following the same concept as the original but bolts the apex of the A frame directly to the differential housing.


The original used a different method of attachment to the axle, adding a secondary A frame. We opted to duplicate the original concept. So the first thing we needed to do was come up with a suitable design.

A preliminary mock up was made using available high tech materials: blue masking tape, welding rod, and cardboard.


Once the high tech mock up seemed workable, a bit of on line research followed to find workable parts. We settled on a spherical bearing as the connection point since it would assure proper motion as the axle moved up and down as it passed over the growing potholes that dominate our local roadways. Then it was time to draw up the plans and come up with a parts list.

The parts total around $120.

(1) Narrow spherical bearing for 1 5/8” bolt. Pegasus 3071-10
(1) Spherical bearing weld cup. Pegasus 1825-150-1187
(2) Chromoly Rod End for 5/8”. Summit PFN-REXMR10
(2) Tube end, weldable, 5/8”. Summit FKB-2107
(2) Clevis brackets, to weld to differential axle tubes. RCR.
(2) 1” OD Chromoly, .083 wall thickness, trim to length
Now the fun part. Construction.


GT40s Supporter
Rear Suspension, Part III, Secondary A Frame

Jigs. We like jigs. It keeps things in their proper position while being built and enables multiple copies to be made that will, hopefully, be exactly the same. So a jig was fabricated from a nice scrap of birch veneer plywood. High tech. This jig serves not one but two functions. First it provides a means of exactly locating the clevis brackets on the axle tubes. Second, it provides a means of assuring the parts are tack welded in the proper position.


A drill press with a tubing cutter attachment was used to fashion the rounded ends of the chromoly that mate with the spherical bearing cup. The heim joint was used to assure all was tight before it was tack welded. Once tack welded it was removed from the jig for final welding.



The same jig assured the exact placement of the clevis brackets on the differential. The differential was flipped upside down and the brackets tack welded in place, after which the jig was removed so final welding could be completed later.


Tack welding complete, the secondary A frame was test fitted. Thanks to the jig, it fit perfectly.


With the axle temporarily connected to the tub, the secondary A frame and the RCR supplied primary A frame were connected and the axle moved through ranges of travel to confirm this design would work. Final welding and painting can now be completed.




GT40s Supporter
Rear Suspension, Part V, Primary A Frame

Once the replacement secondary A frame was fabricated we decided to revise the primary A frame as well. The engineers in the crowd may have noticed that the bolt holding the secondary A frame to the primary A frame is in single shear, which is usually not a good thing where lateral forces are involved. That is, however, exactly the how the original D Type was built. A bit of research revealed that a 5/8” grade 8 bolt has estimated shear strength in excess of 21,000 pounds. I doubt the fact it is single shear will be an issue.

Nonetheless we decided to modify the design of the RCR primary A frame to eliminate the ‘stub’ at the apex and make it more closely resemble the original.

A jig was set up to assure it would be dimensionally exact. It was tack welded on the jig, then removed and finish welded.


The difference in the RCR design and our design is apparent in this photo. RCR used a heim joint to connect the A frame to the differential. Our design uses a 5/8” bolt through a spherical bearing to connect the primary A frame to the secondary A frame.


A pair of spacers was added on either side of the spherical bearing to assure proper clearance as the suspension moved through its range of travel.


Measurements confirmed four inches of travel up and down from normal ride height, which should be more than adequate for the potholed plagued roadways.

Before you get too excited about paint, jump up & down on the pinion and check for flex in your 'new' secondary 'A' frame, Im pretty sure your going to have to add a bracket from the lower rear diff cover bolts to the pivot point once you feed some engine torque into that. Left as is the first time you feed some power into it the pinion will want to climb upwards.
EDIT: Ive attached a dwg of a rear cover Ive used before on OZ Ford Falcon rear axles that spend time on dirt ovals. These cars factory have an alloy rear cover with pivot pin for a watts linkage that does not like gettin hit hard. By using the A-frame as per dwg we got a lower rear roll center plus a setup that was longer lasting. Rear cover is fabbed from 6mm plate and the Bolt is made from HT bar to replace that large bolt you have, The bolt uses a nyloc nut and is free to rotate in the A frame, the bolt that attaches the long 'bolt' to the cover goes thru a sleeve in the large end so it is can be tight, but sleeve allows the A-frame to move up n down as reqd. Overbuilt, yes and unlikely you need to make it as heavy. By making the A-frame swing radius longer it also makes the pinion angle change less thru the range of movement which makes life easier on the rear u-joint of driveshaft.


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