R180 to R200

[madmanadam]

Hi,

Just about ready to swap rear ends.

I have a R180 in the car now which I have abused badly with my V8, and before I put it back on the road I want to swap out rearends.

I have R200 with mustache bar.

Now what should I watch out for?

What is the recommended for bushing (brand & price)?

Is there a tech page I can read on this swap?

Any help would be great just want to be safe before I take this topless flying machine on the road.

 

Thanks

Adam

[pparaska]

Adam, here's how I did it. I yanked the text from my web page on how I went after the driveline issues. See my sig for more info.

I used the poylurethane bushings on the mustache bar and modified the setup as follows:

 

"...stock R200 mustache bar, and this time, I cut 0.3" out of the top of the top polyurethane bushing, and kept the supplied top large steel washer out of the setup. To make this work, I cut 0.3" out of the inner sleeve as well. In all, this raised the rear of the differential by about 0.45" over using the poyurethane bushing kit as supplied. "

 

" The effect of raising the rear of the differential by ~0.45" is to change the angle between the pinion and the horizontal plane by roughly 1.4 degrees. By the way, you can only raise the back of the R200 another 1/4" before it gets too close to the transverse hat stiffener under the floor just above the rear of the diff. "

 

The reason I did that was to raise the rear of the diff to get the driveshaft u-joint angles to down to an acceptable level and to reduce the effect of lowering the car on the halfshaft angles (although this is less critical for the CV halfshafts I have).

 

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Pete Paraska - 73 540Z - Marathon Z Project - pparaska@tidalwave.net">pparaska@tidalwave.net -

[Danno74Z]

Pete,

 

A quick question for you on bring up the rear part of the differential. I'm sure this has to be done because just about everyone has done it and most if not all vibrations go away. What is the reason? Is it just the fact that when one lowers the car this exacerbates an already marginal situation? Does the V8 swap cause additional problems? If an individual just lowered the car would he/she still have to raise the rear part of the

diff.

 

Thanks,

Danno

[pparaska]

I first read about raising the diff from the stuff Terry Oxandale wrote, that's on the IZCC site. Check out: http://www.zhome.com/rnt/FordPower/HalfShaft.html and:

http://www.zhome.com/rnt/FordPower/AlDiffUpright.html

 

He was having trouble with blowing u-joints in the halfshafts of his lowered, V8 Z and determined that lowering the car moved the hubs up relative to the diff, causing excessive halfshaft u-joint angles, especially when the car squatted under hard acceleration. He raised the diff to alleviate that problem. So that's one reason to raise the differential - to alleviate the halfshaft angularity on a lowered, powerful Z. I did it for that reason, but then went to CV shafts, so it is less critical.

 

The other reason is because of the JTR setup. I think that for most people's swap that follow the JTR design (1/2" spacers between the frame rails and the engine crossmember, and the JTR trans crossmember and GM trans mount), that the angle of the crank/trans output shaft is too shallow (doesn't point upward enough going from rear to front) and too low in the car, relative to the pinion centerline of the diff with the stock R200 mounting. The diff pinion angle is more nose up than the tranny output shaft centerlie angle, with JTR mounting technique, creating largely different driveshaft angles.

 

Then there is the issue of the centerlines of the tranny output shaft and the pinion being too far apart vertically. That causes large u-joint angles front and rear. Not good.

 

Lowering the engine with those 1/2" spacer above the engine crossmember wasn't needed in all the JTR Z's I've seen for bellhousing clearance at the top of the tunnel anyway. So I say try taking them out, and try raising the rear of the trans to raise the tranny centerline, but not causing it to be even more shallow. The diff in it's stock mounting is fairly nose up, and you want to mimic the pinion angle. If you raise the rear of the diff, the pinion angle relative to the ground is more shallow, more closely matching the tranny output shaft angle with the JTR install methods.

 

Now my car has the Tremec, which has a different mounting pad to output shaft distance than the GM transmissions, so I had to do even more to make things work. But since so many others have had the driveline vibration and even JTR now recommends raising the rear of the diff, I think I am correct about the angles being too large and not equal on the driveshaft. Check out my page, as there is some info there on what the angle issues are in the V8Z, and what are the possibilities of fixing them. I will briefly discuss them below.

 

First, get the angle finder from Jegs. P/N 247-5020. $23.99. Measure the u-joint angles. I used the starter mounting area of the block to measure the angle of the tranny/engine relative to the ground. You can also use the water pump mount pads, or the freeze plug opening machined surface right next to them. I had a hard time finding a good surface on the tranny.

 

On the diff, I made sure the dirt and paint build up on the bosses that are verticle, behind the bosses for the front mount. It's a small area, so using the angle finder on it is tricky. I check that they are perpendicular to the input flange, when I had my driveshaft out.

 

On the driveshaft, it's easy to lay the triangular groove of the angle finder against the bottom of the tube. This ought to be very close to parallel with the centerline of the driveshaft, or you are in trouble with that part. Anyway, you can check by rotating the driveshaft with it installed and check several places as it is turned, with the angle finder hanging down.

 

From those 3 angles, you subtract or add the angles, (subtracting 90 degrees where needed) to find the relative angles between the engine and the driveshaft, and the driveshaft and the diff. They should be within a degree of each other, and be less that 4 degrees, 3 would be better.

 

Let me know if all that wasn't clear.

 

Regards, Pete

 

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Pete Paraska - 73 540Z - Marathon Z Project - pparaska@tidalwave.net">pparaska@tidalwave.net -