High torque subframe twist
#1
High torque subframe twist
Hey folks,
I just finished installing a new drivetrain in the electric jag (still need to update that thread) that has a lot more torque and I’ve discovered a new problem…
Under high torque acceleration, the subframe ‘rocks’ around the axle direction so much that the driveshaft lifts up and contacts the driveshaft tunnel! I’ve ordered new subframe and radius arm bushings, but mine aren’t that old so I’m not confident that’ll do the trick. Has anyone successfully solved this problem?
A few ‘before’ and one ‘after’ shot below. 3” driveshaft.
I just finished installing a new drivetrain in the electric jag (still need to update that thread) that has a lot more torque and I’ve discovered a new problem…
Under high torque acceleration, the subframe ‘rocks’ around the axle direction so much that the driveshaft lifts up and contacts the driveshaft tunnel! I’ve ordered new subframe and radius arm bushings, but mine aren’t that old so I’m not confident that’ll do the trick. Has anyone successfully solved this problem?
A few ‘before’ and one ‘after’ shot below. 3” driveshaft.
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Mkii250 (07-05-2021)
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Bry5on (07-05-2021)
#3
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Back in the day, we termed it axle wrap.
1. Long radius arms. Chevrolet trucks used them. NASCAR guys took up on the idea.
2. Traction Masters A firm in LA sold them. Beefed up the front section of the leaf spring with a short arm.
3. Way back a fellow i Ontario designed a track bafor his hot XJS used on the drag strip. Posted on J-L. Durn, name just escaped. His car bought from Andrew Weinberg, Jaguar Specialties. we see him here at times..
Carl
1. Long radius arms. Chevrolet trucks used them. NASCAR guys took up on the idea.
2. Traction Masters A firm in LA sold them. Beefed up the front section of the leaf spring with a short arm.
3. Way back a fellow i Ontario designed a track bafor his hot XJS used on the drag strip. Posted on J-L. Durn, name just escaped. His car bought from Andrew Weinberg, Jaguar Specialties. we see him here at times..
Carl
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motorcarman (07-05-2021)
#4
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LT1 jaguar (07-05-2021)
#6
Back in the day, we termed it axle wrap.
1. Long radius arms. Chevrolet trucks used them. NASCAR guys took up on the idea.
2. Traction Masters A firm in LA sold them. Beefed up the front section of the leaf spring with a short arm.
3. Way back a fellow i Ontario designed a track bafor his hot XJS used on the drag strip. Posted on J-L. Durn, name just escaped. His car bought from Andrew Weinberg, Jaguar Specialties. we see him here at times..
Carl
1. Long radius arms. Chevrolet trucks used them. NASCAR guys took up on the idea.
2. Traction Masters A firm in LA sold them. Beefed up the front section of the leaf spring with a short arm.
3. Way back a fellow i Ontario designed a track bafor his hot XJS used on the drag strip. Posted on J-L. Durn, name just escaped. His car bought from Andrew Weinberg, Jaguar Specialties. we see him here at times..
Carl
He did weld some serious torque rods to keep the rear 'happy'.
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#8
I’m using the one piece, other than the rub I get if I act stupid on the throttle the difference is negligible, I do t recall the size now but it may be in the swap manual, you cannot go over a certain diameter driveshaft, I stayed without what I was told, and as measured when car isn’t moving I have just over half inch clearance, but there’s a small dimple the protrudes into tunnel and theta what rubs on mine.
just like all the issues I have run into, I will sort it out!
just like all the issues I have run into, I will sort it out!
#9
#11
Thanks for that tip. I've already elongated the flange holes in the head pipes so that I could rotate them to gain a little more clearance on the rack and move away from the "frame" on the right side. Because the drive train was out of the car when I bought it, I had no idea the drive shaft would run so close. I'd better roll under and contemplate the best way stabilize the bottom of the cage.
The motor/trans mounts fit perfectly, I don't think I could move the engine if I wanted to.
I can see where the diameter of the drive shaft would be very important if it runs that close to the floor pan.
Dave
The motor/trans mounts fit perfectly, I don't think I could move the engine if I wanted to.
I can see where the diameter of the drive shaft would be very important if it runs that close to the floor pan.
Dave
#12
#13
Hey folks,
I just finished installing a new drivetrain in the electric jag (still need to update that thread) that has a lot more torque and I’ve discovered a new problem…
Under high torque acceleration, the subframe ‘rocks’ around the axle direction so much that the driveshaft lifts up and contacts the driveshaft tunnel! I’ve ordered new subframe and radius arm bushings, but mine aren’t that old so I’m not confident that’ll do the trick. Has anyone successfully solved this problem?
I just finished installing a new drivetrain in the electric jag (still need to update that thread) that has a lot more torque and I’ve discovered a new problem…
Under high torque acceleration, the subframe ‘rocks’ around the axle direction so much that the driveshaft lifts up and contacts the driveshaft tunnel! I’ve ordered new subframe and radius arm bushings, but mine aren’t that old so I’m not confident that’ll do the trick. Has anyone successfully solved this problem?
https://www.jaguarforums.com/forum/x...9/#post1865899
This is the idea... ended up running two rods from the diff plate to fabricated bushings mounted to center bearing mounting holes. So far so good. I'm running 450HP on sticky Michelin Super Sports and it has survived many track days with a manual. I'll post up a pict asap.
#14
Darren, Clyde, icsamerica (don't know your name), do you think the 2-piece drive shaft would have more clearance or move vertically a less amount? I'm assuming I will need to adjust the front drive shaft if I keep the 2-piecer. That being the rubber isolated shaft, a new one will be need, rear shaft will be OK as-is.
Dave
Dave
#15
#16
Bry5on, thanks for that bit of information. The ability of the stock center support being able maintain the center U-joint in it's proper position had crossed my mind. I'm thinking my mileage may be a little different than your, but there is no doubt that I will need to show off on occasion.
Dave
Dave
#17
The electric drivetrain does rolling burnouts up to about 30mph, I hear you
For what it’s worth, I’ve decided to go back to a two piece and try to solve the center support bearing issue. There’s not much to be gained from a one piece and adding a bunch of structural supports just to make that happen doesn’t seem worth it to me. On to driveshaft #3!
For what it’s worth, I’ve decided to go back to a two piece and try to solve the center support bearing issue. There’s not much to be gained from a one piece and adding a bunch of structural supports just to make that happen doesn’t seem worth it to me. On to driveshaft #3!
Last edited by Bry5on; 07-06-2021 at 12:28 AM.
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LT1 jaguar (07-06-2021)
#18
I am going to take the liberty to quote some info I have from a known purveyor of Jaguar Conversions.
QUOTE: "The recommended driveshaft tube diameter is 2 1/2" for all applications to avoid interference issues in the transmission tunnel"
When I spoke to my driveshaft builder he recommended 2 3/4" which is what I went with.
I will wait to see what would happen under hard acceleration.
QUOTE: "The recommended driveshaft tube diameter is 2 1/2" for all applications to avoid interference issues in the transmission tunnel"
When I spoke to my driveshaft builder he recommended 2 3/4" which is what I went with.
I will wait to see what would happen under hard acceleration.
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LT1 jaguar (07-06-2021)