JPC Driveshaft

JTGrant

New Member
Aug 2, 2005
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I would like to here from people who have JPC's driveshaft or a similar setup. I realize that the stock shaft weighs in at 48 lbs and the JPC is around 17 lbs. I was thinking, that much of a reduction in rotational mass would really make a diference in the performance of the car. Has anyone dynoed with a light weight shaft? Track experience?
 
Actually mine only weighed 39lbs, but that is still a significant amount compared to aluminum or chromoly. I have not installed my shaft yet as it is still being assembled
(parts on back order) so I can not comment on the rest but a 22lb drop in rotational mass should free up quite a few ponies.
 
I didn't do a before/after dyno, but I can tell you that I wish I'd have done my aluminum driveshaft WAY SOONER. I think it helped more than the 4.10's, on street tires anyway. I got mine from PSI Performance. I picked up 1.05 mph after I installed my aluminum driveshaft & 4.10's... but I'll be honest, there are alot of variables in that equation. I went to a different track, air quality was probably a tad better; but to level things out, the track prep was pretty much comparable and the 4.10's IMO *slightly* hurt my trap speed because of the extra 4th gear shift. So take my 1.05 mph gain FWIW.
 
I've got a JPC shaft and an aluminum flywheel. What a difference! 60ft times will go down substantially with both. I did them at the same time so I can't comment on the shaft alone. I've had no vibration problems, but you should beware, that fat sucker will rub the tranny tunnel under the back seat if you are lowered too much. I'm lowered 3/4'' and had to beat a couple of dents in the tunnel to keep it from rubbing. I plan on putting an adjustable upper on and dropping the rear another 1/2'' in the future.
 
Don't forget the two on the center, and you probably won't even need to mess w/ the exhaust depending on how high you are on jackstands. You should be able to slide the stock shaft out rearward and the new in in reverse order. That is so long as
you are not running some crazy exhaust setup.
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okay I installed the shaft and it took a few combinations on the pinoin yoke to get the vibration out of it. I had to add a hose clamp to get the rest of the vibration out of it. I did install the shaft the way it came, but at the same time the pinon yoke on these cars are different. So that also plays a role in the balance of it all. There is an adapter on the JPC shaft that bolts to the factory pinion yoke. There was a factory mark on the pinion yoke where the factory weight on the end of the shaft would line up. So I installed a hose clamp on the pinion yoke where the factory mark was. The vibrate is almost gone. I even tried installing the shaft 180 degrees and it really made no difference.


Now onto the performance and SOTP feeling. The shaft really makes the cars accel faster. Especially off the line and midrange. I can't really feel a difference at higher rpms but maybe that is because it pulls much harder at low and midrange rpms. Over all I am very happy with the difference in performance with the new shaft. This is a must to have on these cars. I would recommed this mod to anyone. They (the driveshaft shop)are currently making a 3.5in shaft instead of the 4in, because of clearance issues on lowered cars.

Check out there website:

www.driveshaftshop.com

Or call JPC.
 
what kind of write up does someone need? it's 4 bolts to move mid pipes and a handfull on both ends of driveshaft to remove then install new one. not very hard. backyard mech can do it in half hour!

posts like JT's (above) are very helpful to someone trying to research a particular mod. its always the simple tips that help someone out. the same part from different manufacturers can have different installation issues, and having someone walk through it step by step allows members to prepare themselves for future mods.

also, what is simple to one person is a challenge to another. not everyone has the same automotive knowledge.
 
posts like JT's (above) are very helpful to someone trying to research a particular mod. its always the simple tips that help someone out. the same part from different manufacturers can have different installation issues, and having someone walk through it step by step allows members to prepare themselves for future mods.



Also those four simple bolts take a while to run down because of the clearance between the u-joint and where the bolts go. You can't run the down with a socket, you must run them down with an open end wrench and then run them down with a ratchet wrench or a socket and ratchet. That is whatt takes most of the time. Then when you must removed the shaft to rotate it. It is an even more of a pain in the ass to run them out becuase of the lock tight. There was no instructions on torque specs but:

Use locktight on all bolts
4 bolts where the shaft meets the trans 76 ft lb (Factory specs)

6 bolts where the adapter bolts to the pinion yoke 60 ft lb in steps and star pattern

4 bolts where shaft meets adaptor 50 fi lbs in a star pattern