That's not gonna work as well as you'd like. The diff will still knee up and that design basically acts like a 3rd trailing arm, The 2 already there don't help, a 3rd isn't gonna help either. Just copy what I did. It's elegant and track tested.

You might also want to look how Jag did it on the XJ40, Similar to the way I did, solid at the diff with a forward horizontal bushing.

 

I've just finished one of the major projects slated for this winter. Another major piece of engine work has been completed, but that's for another time.

After reading this thread a couple of times, I decided to look at the new cage mounts to see how they were holding up. The rear mounts were showing small separations of the rubber from the mounting plate. I had managed a few spirited take-offs last year, so I thought I'd build some sort of cage control arms. After looking at the posts in this thread, I thought something like Clyde (lickahotskillet) fabricated in post #48 made sense and was within my range of patience, skill, and fighting the exhaust. It is not up to circuit racing spec's and the orientation of the control rods is not technically correct. But I believe this setup will work and if it doesn't, I'll fix it.

Dave

 

LT1
Very smart fabrication, and I have one question/suggestion. In this photo:

I think that the new arms/subframe rear, will tend to be thrust downwards as the subframe twists up at the front under accelleration? If I am right, then it is only the resistance of the bushes that can stop this motion, which seems a bit unlikely.
It might be an improvement to install a third set of bushes on each new arm (or a bolt with suitably bushed fixings at the floor end) also connecting to a suitably reinforced strip inside the trunk, an inch or two from the leading edge of the trunk floor. This would mean that the twisting moment was being prevented completely.

 

Good points, Greg, I will be watching the performance of my setup closely. I might make some sort of gauge/indicator attached to the new bottom plate to measure the actual downward movement. My thinking was that the downward thrust distance would be much less than uncontrolled forward distance and that the bushes would absorb the up/down motion. Thank you for your observation and comments, If this doesn't workout, it's back to the drawing board.

Dave

 

Go back and re-read post 58 and 61. No need to re-invent the wheel. The solution I detailed makes no permanent mods to the car and mounts to a very solid location, it also require s 1/2 the bushings and is track tested.

 

I've looked at them both before. Go and read, or re-read, post #174 of my car build thread, you'll see why I don't build control bars in front of the cage. Everyone here has re-invented a wheel or two, they never were a "one size fits all".

https://www.jaguarforums.com/forum/x...j6-lt1-211881/

 

Why? Is your exhaust in the way? There is acres of room under there for all to co-exist. Nice color BTW. The floor under the spare is very flexible. You'd be OK with a single strut down the middle with the HP / TQ of the LT1. I'm making one like that now for a XJR powered 5 speed coupe that's doing the twist.

You also want to attach the strut somewhat away from the edge of the cage plate. The diff will want to rotate around an imaginary vertical axis line that is inside of the cage counting points. Putting the strut mount point on outside of the cage mount points will put the strut at a disadvantage and may exaggerate the twisting resultant force and create a snap motion when stressed. I'm sorry to be coarse but this is not "one size fits all", it's physics, and a straight forward vector problem. That's said at LT1 power levels it's probably a net positive as it is.






Seem like the exhaust hangers are in the way, may have to move them

Is the Pict below you can still see the witness mark on the drive shaft when my cage was twisting up. I now have a 2 piece shaft setup becasue this shaft was balanced but still vibrated above 120.

 

Thanks for the opinion and advise, I'll see how mine works and go from there. My version is more of a preventative measure than a solution of an existing problem.

Dave

 

Regardless of what works or what doesn't, I am enjoying the innovative solutions everyone is coming up with to combat the axle wrap.

I'm working on an updated modification to my front-facing "traction bars" and will post pictures once we get there.

 

Just throwing my 2 cents in but, has anyone seen the design that Evolution E Type came up with? Im sure you could reverse engineer what they did.

 

Very, very nice!! Too much unobtainium for my shop or wallet, but definitely a good candidate for some reverse engineering, as you say.

Dave

 

The bump stops actually didn't work out. Way too soft, and the arms were bending a bit too. Driveshaft still hitting the tunnel. So, I spent some time yesterday on my day off modifying the arms. I notched the arms in a few locations to angle them upwards and intersect some plates bolted to the center support bearing mount holes. Painted over the scrape marks on the driveshaft, welded it up, took it out, and....









Where I'm pointing is where the contact was, and the paint is still intact indicating no contact. The bending force has been partially converted into compression where the square tubing is much stronger. I beat the thing up pretty hard especially in the lower gears where the torque applied to the subframe is highest, and it's locked down.





Great success! Time to turn the boost up!

 

 

I just complete an XJR6 manual swapped Coupe. It ripped up the subframe bushing in-less than 100 miles. I incorrectly thought that because it was making less than 350HP the brace may not be needed. I was wrong... so I made a modified light duty version of my original track tested version and this one is good enough to handle the 330HP of the slightly modified XJR engine. It works well, no more wheel hop. It was made from some repurposed Jag bits and 2 soft Energy suspension Urethane shock eye bushings. This lighter duty version gets the job done and needed to be shorter than the original because of how the exhaust system is configured.






XJR6 ripped a new set of bushing fast

before the brace, obvious witness marks.

 

I'm surprised the mount didn't hold up, as the 6.0 V12 in an XJS has similar power and the mounts seem to stand up ok. Were they OE mounts?

Are you using the original XJR mufflers? I'm in the process of doing an XJR engine swap and was thinking of using XJ8 mufflers. I want similar to original XJ noise levels, but not to be too restrictive.

 

The mounts were CBC-5737 or XJS converible mounts. If you look close you can see the P/N.

I'm Using the complete stock normally aspirated exhaust system that was found on a 4.0 XJS. This car is a cruiser and exhaust mods was not part of the commission. The stock system is well designed with large high flowing cats and two mufflers. This setup should be OK up to 350HP. I think any alterations would offer up more noise than power. A low rev'ing supercharged engine wont benefit as much from a freer flowing exhaust like a rev'y NA car would.

I have a 6.0 V12 XJS . No comparison in power to an XJR6. The XJR6 makes all the troque right off idle and keeps the boot on your neck until 4500 RPM where it starts to roll off. The V12 in the XJS just starts to wind up and come alive around 3500 RPM and remains strong but flat to redline. The XJS 6.0 V12 had a 1/4 mile time of about 16 seconds. The XJR was in the high 14's, thats a big differance.

Back in 1995 when you could buy an XJ sedan with the most developed 6.0 V12 Jag ever made it was still considerable slower than the XJ6R. The 1995 v12 in the sedan was more powerful than the 6.0 found in XJS becasue of more agressive ignition timing and a better air intake system. Even so a road test magazine suggested the XJ6R was quicker by 1 second in the 1/4 mile and 0 to 60 than the more developed V12 in the sedan.

 

Wow, fantastic info in this continuing thread. Thanks to all and please keep this thread alive and evolving.