In reply to Stu Lasswell :
Yup, it's really low. Not clear how I make it less so without cutting and welding.
In reply to Stu Lasswell :
Yup, it's really low. Not clear how I make it less so without cutting and welding.
I hope we can come up with a better solution, 'cuz I'm not a "cutting and welding" guy like you!
I think I lost the plot. Was there some indication that the Nissan/Infiniti diff would be a straight bolt-in?
By the way, have you determined the angle of the driveshaft yoke misalignment/offset? If I recall correctly, there’s an optimum to shoot for. 3deg., maybe?
In reply to Slow_M :
The R200 diff conversion is indeed supposed to be a straight bolt-on kit (at least for a TR6). As the 2500M uses the TR6 diff. and mounting arrangement, in theory at least it should also be a "bolt-on, drop in" install.
It's all a kit from Good Parts - the TR-6 upgrade people. And as I understood it, it should bolt right in to the back end of a TVR.
Well, it goes in:
But I can't say that it fits:
Beyond being way too low, the input flange is actually locked on the tube in front of it.
So that ain't gonna berkeleying work.
The diff will have to at least go up about 3/4". I'd sure like to push it back a little too. There really isn't much of any adjustment here. Maybe a tiny bit back, unless I start slotting holes.
Still holding out hope I've put something together wrong, but I strongly doubt it.
I'm pretty frustrated at the moment.
In reply to TVR Scott (Forum Supporter) :
I might be way off base, but could you cut out the tube in front of the flange and weld in a new piece that is angled on the ends so it clears the driveshaft? Kinda like three sides of a trapezoid? Or a shallow "u"?
The problem here is that a TR6 does not have a tube across the frame immediately in front of the diff. It only has a bead rolled sheet at the bottom of the tubes. Look at the illustration in the Moss catalog, you'll see it.
I know that many TVRs have been fitted with this conversion... I'm sure when we hear back from Richard Good all will be revealed. At least I sure hope so!
I e-mailed him. We'll see what he says.
The nose on this diff is a lot longer than the original. With the TR6 unit, the driveshaft just went over the cross-member and cleared just fine.
Barring some glorious mistake I've made, I'm planning on fabricating a new adapter frame to replace the original TVR unit.
TurnerX19 said:The problem here is that a TR6 does not have a tube across the frame immediately in front of the diff. It only has a bead rolled sheet at the bottom of the tubes. Look at the illustration in the Moss catalog, you'll see it.
I'm definitely lost. The piece of square tubing jammed into the diff flange? That's the input flange, right? The tube with the red arrow can be moved, correct?
In reply to Recon1342 :
Yes. In theory, I could chop out that tube and move it. It is one possibility.
In reply to TVR Scott (Forum Supporter) :
Whew! I'm glad there are options, mainly, but I'm also glad you confirmed I was looking at it correctly.
Yeah, that is possible. The downside is that cross-member is directly connected to the front mounts on the LCA. So any butchery there would need significant reinforcement to reestablish that load-path.
And I just painted the frame.
And took it off the rotisserie.
Now I'm just being pissy.
I haven't really looked at my Goodparts kit, but those polyurethane isolator bushings look pretty thick. Couldn't they be cut like in half or so on the top, thereby raising the entire diff by the same amount? Another thought...could the diff hanger cage be modified to hold the diff higher in the frame (assuming there's room under the body)? Might either such alternative modification result in unacceptable drive shaft angles, or could that be compensated for at the trans mount? Hey, I'm no engineer, just hoping for an easier way around this conundrum.
In reply to TVR Scott (Forum Supporter) :
It's all good. The gods of DIY declared long ago that such discoveries are only to be made once it is inconvenient to fix them.
Recon1342 said:In reply to TVR Scott (Forum Supporter) :
It's all good. The gods of DIY declared long ago that such discoveries are only to be made once it is inconvenient to fix them.
absofriggenlutely. and thine messengers name shall be.. Murfious!
So it would appear Richard Good doesn't really know how an R200 fits in a TVR. That's fine. We've got to be only a very small percentage of his business.
I'll figure it out one way or another.
Did some measuring, tightening, tweaking, rearranging, loosening, and shifting.
If I remove 1/2" from the front two mounts it should fit beautifully:
Clears the tube just fine, axle locations are about the same, clears at the back end. Pinion angle is about 2-1/2 deg. So I'll be busting out me metal-destruction tools and will make the mod.
Checked the angle at the transmission, and it's pretty darn similar - maybe 2 deg:
Now this brings up more questions. The two driveshaft points aren't quite inline. Holding up a t-square shows the back end is a little bit higher than the trans. Also the back end is offset a bit from centerline. How well is the drive shaft going to deal with these differences in alignment?
In reply to TVR Scott (Forum Supporter) :
I would think/hope it should be no problem. U-joints at both ends (as opposed to Guibo, etc), right? Don't most driveshafts spend the bulk of their lives significantly out of straight-line alignment? I have it in my head that "perfect" alignment results in brinelling because the bearings bear constantly in a single spot.
I would also think that the more misalignment you have, the more important matching those angles becomes, though I could be wrong about that. I don't know off the top of my head how concerned to be about 0.5 deg.
As indicated in your pictures, both trans and rear are angled up. This will cause a whip in the driveshaft and a pronounced vibration. It is my understanding and experience that the angles must offset each other, also referred to as broken back alignment. You can simply lower the rear of the trans to achieve this.
Looking at the front mount in the pic, are there two bushings under the mount and above the diff or it a case of black metal and black bushing looking the same?
In reply to MrJoshua :
It's a little hard to see because everything is sort of the same size and shape, and the same color. (Switching to bullet-point mode)
With this arrangement I can use spacers to move the diff nose down, but there's not any provision to move the nose up.
I've been doing more research on the driveshaft alignment, and have pretty well squared things in my mind. The following is from a Spicer driveshaft tech manual:
So essentially I want to make sure the output and input are pretty close to parallel both vertically and horizontally, and make sure the total angle is within the allowable range for the driveshaft.
I already know from earlier today that I'm within about a half degree vertically. Both components will be straight front-to-back, so that good too. Then I just need to look at the difference between centerlines. Other than that, I see no issues.
That was my understanding, that the diff input and transmission output had to be parallel axis, but should be offset at least a little for u-joint bearing reasons.
A little steering rack research - evidently a Spitfire rack is almost the same width as the 2000 rack - just 660 mm instead of 665. Quicker ratio though - with a 7 tooth pinion instead of 6. The GT-6 had the same slower ratio as the 2000 - more weight on the front end.
The TR6 rack is narrower - 650 mm, but has the quicker-steering 7 tooth pinion.
Some mixing and matching may come into play here.
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