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Discussion Starter #1
I am thinking of replacing the rear transmission support bushing on my 2l gtv. The gearbox seems bouncy when driving over bumps, etc. the stock "thong" type bushing does not seem stiff enough to me. Two choices I have been considering are using the earlier model bushing, which is less cut away (centerline lists this as a performance upgrade for the 2l) or using paul spruell's aftermarket kit.

Can someone weigh in on the pros and cons? Does anyone have experience with the spruell set up?

thanks
 

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I installed Paul Spruell's rear tranny mount and also the motor mount reinforcements. I like the way they have made the engine and tranny seem more a part of the car. My car is a 75 Spider with IAP performance springs, Koni shocks (almost full stiff on the front and 2/3s on the rear), and poly sway bar bushings. So the car is pretty stiff to begin with. The Spruell set up will allow a lot more of the engine/tranny vibrations and torque to pass on to the body but I like the feel. If it was a daily driver/tourer then I might change my mind.

Install was a no brainer.

Here are some pics.
 

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Discussion Starter #3
thanks

Thanks for the feedback. when I talked to my mechanic, he was opposed saying "you need that flexibility or other things will start to break". are you aware of anything that would be overstressed by stiffening these mounts up? Have you had anything crack (frame, mounts, driveline) or break?

thanks again.:)
 

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No cracks yet anywhere......... I only have about 1500 miles on the car since the new engine with the upgrades went in. I guess the rear tranny mount crossbar may be getting more stress with the new stiff mount but up front on the motor mounts I would not think there would be much of a problem.
 

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on a race car, sure
on a streetcar, never.

Plenty of NVH problems by stiffening the mounts, gear whine being the biggest problem I'm guessing.
 

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When ordering the transmission rubber bushing for my 66 GT junior, 2 types were available, 1 for hydraulic clutch and 1 for mechanical clutch. I took the last one because my car has mechanical clutch, but I think it was the wrong choise. I noticed the old bushing was all softened up by oil due to a leaky transmission (shifting tower). Now I have much more vibrations, probably because the bushing is very stiff. I have tried to take out the two plastic pins but without succes. Next winter I'll change to a hydraulic type bushing, it has much less rubber and must therefore absorb vibrations better.
 

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But the geometry is different

Maybe I'm picking nits here, but isn't Spruell or anyone else troubled by the difference in geometry between the stock mount and the stiffer alternative? I have re-posted the photo that Torica posted on 6/28. Seems that the transmission would sit lower with a mount that has its mounting bolt hole centered relative to the OD (as the Spruell mount appears to), since the stock mount has this hole biased toward the bottom.

Dropping the trans relative to the bearing that supports the front driveshaft would a) put an angular flex into the giubo joint (which will shorten its life), and b) present a different angle between the rear of the front driveshaft, and the front of the differential (U joint pairs don't deliver a constant velocity with a difference in angle).

A solution might be to add washers between the front driveshaft bearing's two mounting "ears" and the body to drop it by the same amount (assuming the studs are long enough). You want to have single, straight axis through the front driveshaft, transmission mainshaft, and engine crankshaft.
 

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Maybe I'm picking nits here, but isn't Spruell or anyone else troubled by the difference in geometry between the stock mount and the stiffer alternative? I have re-posted the photo that Torica posted on 6/28. Seems that the transmission would sit lower with a mount that has its mounting bolt hole centered relative to the OD (as the Spruell mount appears to), since the stock mount has this hole biased toward the bottom.

Dropping the trans relative to the bearing that supports the front driveshaft would a) put an angular flex into the giubo joint (which will shorten its life), and b) present a different angle between the rear of the front driveshaft, and the front of the differential (U joint pairs don't deliver a constant velocity with a difference in angle).

A solution might be to add washers between the front driveshaft bearing's two mounting "ears" and the body to drop it by the same amount (assuming the studs are long enough). You want to have single, straight axis through the front driveshaft, transmission mainshaft, and engine crankshaft.
The weight of the transmission pulls the mount point towards center anyway. And, the factory one has such a large range of motion that I am sure the spruell one is well within that range considering it has very little range of motion.
 

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Mhunger, have you done the aft mount job yet? I`m going to do mine and am wondering how you got the old one out and new one in?
 

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Discussion Starter #12
rear mount job

No, I haven't done it yet. there is a special puller a local mechanic lets me use. He also says you can heat the surround with a propane torch and then push it out, but I like the first method better.
 

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I made a removal tool out of a few pieces of pipe and a threaded rod. Find a pipe that just fits inside the housing (just smaller than the bushing but bears on the metal edge), and another that fits outside. Both about 4-6 inches long. A thick flat washer larger than either or a square bit of steel with a 3/8 hole on both sides, and a threaded rod. Just crank the nut on the small side and push the bushing into the pocket created by the larger one.

I have a shop press from harbor freight so its even easier; you only need the smaller pipe bit, and use the standard bearing plates that come with the press (of course this only works if the tx is out of the car, otherwise use the threaded rod)....

Robert
 

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Rear transmission mount differences

The height of the rear mount and the crossmember is different between the mechanical clutch and hydralic clutch. Substituting the rear mounts can cause a missalignment of the "donut" and of the u-joints, resulting in a vibration that is hard to solve, let alone increasing wear on the components.

Stick to the correct parts unless you are familiar with gauging driveline angles.
 

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Even the German repro rubber mechanical clutch type mounts (for early GTV, TI, Super, Duetto) are much stiffer than the original Alfa ones. I had one in my 67 Super briefly and could not stand the vibration. I went back to a hydraulic type mount, with a rubber bumper to stop trans fore/aft movement, and am much happier. I can back up just fine now without axle judder.

Andrew
 

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Discussion Starter #18
The height of the rear mount and the crossmember is different between the mechanical clutch and hydralic clutch. Substituting the rear mounts can cause a missalignment of the "donut" and of the u-joints, resulting in a vibration that is hard to solve, let alone increasing wear on the components.

Stick to the correct parts unless you are familiar with gauging driveline angles.
what if you changed from a 1600 to a 2l engine and tranny in a 66 sprint GT, but kept the rear transmission mounting bracket? which bushing should you use? I currently have the 2l bushing in there, but it seems too soft, and I was going to substitute the large O.D. 1600 bushing.

thanks
 

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The trans is meant to move around some. The aftermarket mechanical clutch (1600) mounts will, in my view, allow too much vibration through. The hydraulic clutch mounts dampen the vibration better, but make it hard to back up in a mechanical clutch car without some kind of rubber bump-stop arrangement to keep the trans from moving fore/aft in reverse.

Andrew
 

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Discussion Starter #20
I am still having a bit of a problem. to recap, I have a 2l driveline in a 66 sprint gt. I have the 2l tranny support bushing. I don't know which support bracket I have. It could well be the original one. The driveline makes a noise / vibration when coming off the throttle at highway speeds. I have 2 questions:
1) is there any way to tell if I have the earlier or later tranny support bracket
2) how can I check for the proper driveline angle.

any help would be much appreciated

marc
 
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