Intermediate shaft questions

[AlfonsoR]

Guys, i've been doing some research on intermediate shaft. My car is an 89 3.2 with 105k miles on it, i've had it for about 6k miles.

I'm planning on doing an engine drop in the next few months to repair some oil leaks, and am leaning towards opening up the bottom end only because I've seen a few posts where people have opened up the bottom end and found copper showing on the IS bearings. So here go the questions:

1. I want to figure out how to repair or replace IS bearings, gears and shaft so that my engine bottom end will run to at least 300k miles or more. So I think I have to figure out what causes some engines to show copper in the 80-100k mile range, while others report their 3.0s and 3.2s run 200k miles without opening the bottom end. Is it poor maintenance or poor lubrication properties of the oil being used?

2. Are there any upgrades worth doing to ensure longer service life? I have read you can use straight cut gears, which takes out the thrust component of the helical or angle gears, but yes I have also read these things are loud. Is anybody running straight gears on their street car? Are the gears loud in a good way? Maybe the straight gears will make my engine sound like a Lambo V12.

Thanks for your help.

[BURN-BROS]

It is common to see high wear at the IS bearings even with low hour motors.

I would not recommend splitting a case. If you did the wear would be right back. These engines can last for quite a long time if you do the maintainance.

[brads911sc]

if you open her up get the bearing treated at WPC. reduces friction by 50% and doesnt change tolerances... many guru's including charles navarro swear by it...

[AlfonsoR]

Originally Posted by BURN-BROS

It is common to see high wear at the IS bearings even with low hour motors.

I would not recommend splitting a case. If you did the wear would be right back. These engines can last for quite a long time if you do the maintainance.

Aaron, at what point would you recommend the case be opened to check the intermediate shaft? I think I read where someone lost the aluminum gear and caused serious damage to the engine.

Does the same wear occur with straight tooth gears?

[Flieger]

I have heard that the wear on the intermediate shaft bearings are mainly from the chain tension on the end of the shaft causing a moment within it.

[AlfonsoR]

Originally Posted by brads911sc

if you open her up get the bearing treated at WPC. reduces friction by 50% and doesnt change tolerances... many guru's including charles navarro swear by it...

Brad, I live in Missouri City. Where did you get the WPC coating? I see they have several offices.

Looking further down the slippery slope, errr mountain side, I might replace all the bearings and have those coated too. Hmmmm...wondering if it would be worth doing a thermal coating on the pistons and valve bowls even if I re-use the ones in there? Also wondering if I have Nikasil cylinders? Just a bunch of random thoughts popping in my little brain.

Also, where did you get your machine work done and engine components checked out? i.e., if I do the split, I would want someone to inspect the bearing clearances and journal diameters. I have a set of mics but I don't do that stuff enough to trust myself.

Thanks

[lindy 911]

If you have your motor out and on a stand to do a top end, it's not that much more involved to split the case. If you have a concern about the bearings go for it. You might pull the cap from one of the rods and get an idea of the bearing condition for that rod. If it looks good, chances are that the rest of the bearings will look the same.

There are some good sources for the work you're looking for right here in the Houston area. I used Poly-Dyne for the coatings on my bearings and piston skirts. They also did the thermal coat on my pistons. It's different technology than that used by Brad, but a lot of the hard core race motor builders in the area think it's best.

Depending on your schedule, William Knight is moving to Sugarland in January. He would be an excellent choice for the inspections you are seeking. Mike Callas is also pretty good, from what I understand but be prepared to open your wallet.

There is a ton of very useful info on this site. If you take your time and do some research, your rebuild will be a piece of cake.



Lindy

[BURN-BROS]

Originally Posted by AlfonsoR

Aaron, at what point would you recommend the case be opened to check the intermediate shaft? I think I read where someone lost the aluminum gear and caused serious damage to the engine.

Does the same wear occur with straight tooth gears?

Hi Alfonso,

When it's time to replace main bearings or you have a leak that requires splitting the case. It's not a potential issue that I would use as an excuse to split the case.

Now if you are dieing to split the case, by all means replace. However, the upgrade I would do on a 3.2 would be ARP rod bolts and the bearing coatings are very nice.

You will need to have the rods resized if you upgrade the rod bolts.

[AlfonsoR]

Originally Posted by lindy 911

If you have your motor out and on a stand to do a top end, it's not that much more involved to split the case. If you have a concern about the bearings go for it. You might pull the cap from one of the rods and get an idea of the bearing condition for that rod. If it looks good, chances are that the rest of the bearings will look the same.

There are some good sources for the work you're looking for right here in the Houston area. I used Poly-Dyne for the coatings on my bearings and piston skirts. They also did the thermal coat on my pistons. It's different technology than that used by Brad, but a lot of the hard core race motor builders in the area think it's best.

Depending on your schedule, William Knight is moving to Sugarland in January. He would be an excellent choice for the inspections you are seeking. Mike Callas is also pretty good, from what I understand but be prepared to open your wallet.

There is a ton of very useful info on this site. If you take your time and do some research, your rebuild will be a piece of cake.

Lindy

Hi Lindy,

Thanks for the info on the coatings and yes, I would be interested in getting contact info for William Knight. I am in no hurry and as a matter of fact, before even pull the engine, even if I don't split it, I would like to sell the car next to my 911. It's a 88 BMW 635 that I dont have room for and that needs a little interior work. Selling the bimmer will finance the work I do on my 911 at least for this year. So it will take a few months, I'm sure.

I had a PPI done by M Callas a while back, and he's a great guy and obviously very knowledgeable but besides the wallet factor, it's quite a drive for me and I don't have that kind of schedule flexibility with respect to missing work to go check on things...I like to be at the shop as much as I can just to learn, so I was looking for someone a lot closer. Mr. Knight might be the perfect fit.

[AlfonsoR]

Originally Posted by BURN-BROS

Hi Alfonso,

When it's time to replace main bearings or you have a leak that requires splitting the case. It's not a potential issue that I would use as an excuse to split the case.

Now if you are dieing to split the case, by all means replace. However, the upgrade I would do on a 3.2 would be ARP rod bolts and the bearing coatings are very nice.

You will need to have the rods resized if you upgrade the rod bolts.

Hi Aaron, thanks for your input. I really appreciate the advise.

I think I do have a slight leak, more of a weep, on the case split line. The main oil leak is coming from the oil cooler and possibly the breather too.

Your comments make me breath a little easier.

Do straight gears solve the bearing issue? How much louder are straight gears?


PS: what do you mean by resize the rods for ARPs? I'll do some research in the mean time.

Thanks again!!

[AlfonsoR]

Aaron, so re-size is necessary because the ARP rod bolts provide more clamping load which changes the shape (makes them out of round) of the rod, correct? So the bolts need to be installed then rods need to be bored to make them round again.

Does this mean new bearings would be necessary? If so, what do you recommend?

[Flieger]

Originally Posted by Flieger

I have heard that the wear on the intermediate shaft bearings are mainly from the chain tension on the end of the shaft causing a moment within it.

I do not think the straight cut gears will solve the bearing wear issue. The thrust is axial, not radial, and the bearing does not support that sort of load. It would wear the bearing shoulders or any thrust bearing surfaces.

[burgermeister]

Originally Posted by AlfonsoR

Aaron, so re-size is necessary because the ARP rod bolts provide more clamping load which changes the shape (makes them out of round) of the rod, correct? So the bolts need to be installed then rods need to be bored to make them round again.

I installed ARP rod bolts on my engine and did not resize anything. I plastigaged the rods & bearings on the crank and everything was in spec.

Caveat: I am NOT a rebuilding expert, and my engine is still in the reassembly process.

[brads911sc]

WPC is in CA. I shipped them to CA. Had them back in a week. Total for all Main, Rod and Intermediate bearings was $140 Incl shipping. Cheap insurance.

The Poly Dyn is also very well regarded. I chose WPC because I didnt want to mess with clearances. Its a micro shot peen with tin and other anti wear material.. Poly Dyn is similar materials but is a coating. Both are probably equally good.

In Houston, Id use either M Callas in Sealy (Who I used) or M Crawley at European Auto Technics. Both have old shops filled with old Porsches and have on site machine shops. Both are spendy. My machine work was $800 and its an SC case that didnt need anything. that included having him install the rings and cut them (where needed) (extra $175). Was worth it to me to have that perfect. As a side note.. He didnt install my new wrist pin bushings. Said mine were fine and advised me to use the old ones. So he def isnt trying to sell u extra unneeded work. He marked my pistons based on where he would install them. Very stand up guy...

At either shop Id plan on dropping them off and leaving them for a week...

Originally Posted by AlfonsoR

Brad, I live in Missouri City. Where did you get the WPC coating? I see they have several offices.

Looking further down the slippery slope, errr mountain side, I might replace all the bearings and have those coated too. Hmmmm...wondering if it would be worth doing a thermal coating on the pistons and valve bowls even if I re-use the ones in there? Also wondering if I have Nikasil cylinders? Just a bunch of random thoughts popping in my little brain.

Also, where did you get your machine work done and engine components checked out? i.e., if I do the split, I would want someone to inspect the bearing clearances and journal diameters. I have a set of mics but I don't do that stuff enough to trust myself.

Thanks

[BURN-BROS]

Originally Posted by AlfonsoR

Aaron, so re-size is necessary because the ARP rod bolts provide more clamping load which changes the shape (makes them out of round) of the rod, correct? So the bolts need to be installed then rods need to be bored to make them round again.

Yes.

Originally Posted by AlfonsoR

Does this mean new bearings would be necessary? If so, what do you recommend?

I do. It's not worth it not to.

[BURN-BROS]

Originally Posted by burgermeister

I installed ARP rod bolts on my engine and did not resize anything. I plastigaged the rods & bearings on the crank and everything was in spec.

Caveat: I am NOT a rebuilding expert, and my engine is still in the reassembly process.

Resizing rods takes care of two potential issues

1. maintaining roundness.

2. The Circumference dimension or "bearing crush".

You can obviously install rod bolts and run them without the engine blowing up, but the variance can result in tight spots and loose spots on different areas of the rods. This is not easy to see with a Plastigauge. It will however show up with a bore gauge.

The circumference dimension is particularly important in controlling the bearing from walking especially under higher loads/rpms.

Resizing is a step that everyone should do as the potential problems far outweigh the cost to have the procedure done.

[Walt Fricke]

The "copper" showing on my IS bearings has been on the thrust surface. The radial surface looks fine, but the thrust part looks worn. The #1 main bearing (which is a thrust bearing) has the same issue.

I assume that thrusts from the helical (or whatever they are) IS gears is partly to blame for this. Of course, the clutch also imposes axial loads.

I have straight cut steel IS gears in my 2.7 race motor. But I run straight pipes, so no way to tell about noise. And the current build of this motor has lasted quite a few years, and I don't recall if I have pulled it down since the straight cut gears went in to see if they made any difference.

However, basically this wear on thrust surfaces isn't something one needs to worry about. The rod bearings go first, and while those can be changed without splitting the case, why do it that way? Most just pull everything apart at that point, and all bearings get replaced.

[burgermeister]

As another point of reference, my IS bearings did show copper on the radial surface at 163,000 miles. Also the thrust surface of the IS & crank thrust bearings like Walt mentioned. The most worn parts on the engine, aside from the valve guides, were the rocker shaft bushings.

[Flieger]

How is the end float with the straight cut gears? (axial play)

[gestalt1]

I have a related question, how about on early sand cast cases- is the thrust wear just the shoulder of the intermediate shaft and the aluminum case? These cases have no bearing. I would think a stair cut gear set would help reduce wear quite a bit because there is no thrust forces. Any experience with this?