1969 GT - Need advice

[DriveCrash]

My father had 3 opel gt's in his driveway for years. a 69, 71 and 73. The 71 & 73 were parts cars and didn't have motors.

He suddenly decided to have them all HAULED AWAY.. i was able to save the 69 from destruction by stealing the front suspension off the 73 and getting it out of harms way. (lets not talk about the fact he had two great parts cars crushed.. i'm ashamed of my father now )

So on to my questions..

I have noises and vibrations comming from the rear end. I pulled the center bearing assembly off and put a used on on (with intact bushings on the propeller shaft tube) *hope i have my terms right* and that solved some problems. Today I was driving around and getting alot of pops and clunks from the rear.

I put it up on stands and put it in 4th at idle to try to trace it down. The driver side wheel is wobbling all over the place, and has alot of end play in the half shaft. The passenger side has end play as well, but not as much. I swapped the tires (rims) to see if it was a bent rim, but it's not. Could the half shaft be bent? As far as the noises in the rear go.. after searching it seems like I should be looking at every bearing from transmission output to tire. However with it being a 69 the wheel bearings are not an option? Am I screwed here? I really wish i could have saved the other two opels, they both had rearends I could have taken.

Another problem I have is that at 60mph the engian is doing 3,250 rpms. Is this normal? Can I change out the rear to a different gear ratio to get better rpms at high speed? I know it's probably a pipe dream, but I'd like to be able to do 70mph in 4th at 3,000 ish rpms. I really dont care about acceleration that much.. I dont consider it a fast car, just really stylish.

I saw some posts about changeing the rear axle to another car's axle, but I'm afraid that is well beond my capability.

How much am I looking in parts to get the really bad noises to go away, and how much am I looking at to find a different rear end to put in?

Thanks for the help,
Drive

[oldopelguy]

For a wholesale changeout you want to keep an eye out for a 70-71-ish Kadett with an automatic, they had 3.18 gears and are pretty much your only axle option for reducing the highway rpm. Bonus if it's a wagon and you get the rear sway bar too. Any coil spring Kadett axle or GT axle should work, though, if that's all you can find.

As to pieces/parts, the early axle is pretty much not repairable anymore. You might be able to get someone to come up with the parts, but they'll all be used at this point and might not be much better.

Basicly you're looking for someone who's willing to give up some parts. I'd offer you a known good KAdett axle myself, but the logistics just don't work out before mid-July for getting it your direction.

[Yekim]

Hey for the niose in the rear end you may want to look at your exhaust. I have had that problem as well.

[matl59]

If endplay (in and out motion of the axle) is your problem then I'd say its not really a bearing problem. The endplay you describe is somewhat normal due to its age and the way it was designed. The axles are held in by retaining clips. As the clips and the surfaces they contact wear endplay gets worse. You can check these out by removing the rear diff cover. Mine have some play but have never caused a problem that I'm aware off. Excessive endplay may be from a partially broken or excessively warn clip...

You could still be getting noise from your torque tube mounts. You mention replacing them with intacked ones but I'd urge you to replace with new along with the doughnut inside the end of the tube. Mine were intacted but I had a banging noise. Once I replaced them with new the noise was gone.

You could swap the rear end for a later one or a Kadet axle with a 3.18 gear for better highway milage but then your speedo will be off and I'm not sure you can correct it without having someone recalibrate your speedo. 3250 sounds about right for stock RPM at 60mph...

As mentioned above, the exhaust can also hit and move making sounds that seam like they are coming from the rear end. Check it thoughly as well.

Good Luck!

Matt
69 GT

[opelnut10]

The noise could be a bearing, but it would be unusual for the roller type axle bearing in the 69 rear end housing to go bad, but it is a possiblility. If the bearing is bad they are almost impossible to get. My suggestion, after checking other things mentioned is to look for the Kadett S/W rear complete from an automatic transmission car, just make sure you also get the speedometer gear from the S/W as well, it will help put your speedometer close to being right.

[markandson]

If you have a wobbling wheel then look to the wheel bearings, not at the rear end.

[opelbits]

Drive-

I don't know how St. Louis works for you logistically, but I have spare rearends (even a 69 or two, plus a later non-c-clip rear). I also have a 70 Kadett Rally I'm parting out. It has a swaybar rear end, but I'm not sure of the gearing. The Rally's had 3.67 rear gears, unless they were automatics (which this one is), but I don't know that it is a 3.18. It may be a 3.44 just like what you have.
Generally, if your tires are right around the original stock diameter, then take your rpm in fourth gear, double it, and that is approximately your mph.

With my old Manta, 70mph was 3500rpm with 185/70/13 tires.

[Anonymous D]

Installing a set of Kadett 3.18 gears into a GT (that has anything less than 130hp,or a 2.4L engine at the least) is a bad idea.

Unless you have a very significant upgrade in torque (from the stock engine output), it won't accelerate from a standing start in 1st gear. It will bog down and crawl.

If quieter and more efficient highway performance is what you want, swap the original transmission for the GETRAG 5-speed.

A 3.18 is best, with an injected 2.4L engine (or a non-stock V6), and it will extend your high speed operation.

[RallyBob]

Originally Posted by Anonymous D Installing a set of Kadett 3.18 gears into a GT (that has anything less than 130hp,or a 2.4L engine at the least) is a bad idea. Unless you have a very significant upgrade in torque (from the stock engine output), it won't accelerate from a standing start in 1st gear. It will bog down and crawl. If quieter and more efficient highway performance is what you want, swap the original transmission for the GETRAG 5-speed. A 3.18 is best, with an injected 2.4L engine (or a non-stock V6), and it will extend your high speed operation.

Actually Dave, the difference in 1st gear is not enough to worry about it. 3.43 1st gear ratio w/3.44 final drive/6300 rpms/23.39" tire = 39.23 mph. With the 3.18 final drive, we're looking at 42.44 mph, or about an 8% difference overall.

The difference with the Getrag 5-speed in top gear is far more noticeable, and unless you have an engine with a bunch more grunt, the only place the 5th gear is truly usefull is at high speeds (75 mph+) and on flat roads. Otherwise, you will be downshifting a lot.

The .805 5th gear overdrive effectively makes the new final drive 2.7692 (assuming 3.44 rear axle ratio), and this is a tough gear ratio for 65 hp to push down the road! About a 24% difference...

I'm not saying it's a bad upgrade, but it works best with either a built-up engine, a larger engine (2.2/2.4), or a steeper final drive. I personally liked the Getrag OD when coupled to a 3.89 gear ratio (3.13 final drive), and a strong 2.0 litre engine. It could pull that OD up hills, still had good top end, and much better acceleration than stock. I got 28 mpg driving my Ascona 13 hours to Mid-Ohio racetrack in 1995 with this combination...that's 4 mpg better than stock, yet this was with a modified engine, steeper rear axle ratio, and 300 lbs of tools and parts in my trunk.

The ironic thing is most Opels will still be faster in 4th gear than in 5th, simply because they don't have the torque to overcome the rpm drop.

Bob

[Dmcbrass]

Wheel bearings have nothing to do with axle end play on the earlier style rear ends. The wheel bearings only carry radial load. Thrust load is handled through the differential bearings. While a small amount of end play is normal on the 1970 and earilier rear axles, excessive end play on one side is worrisome. It could be a bad differential bearing or a very worn axle clip. Unfortunately I would bet on the differential bearing. You need to check this out before driving the car again. The failure of the clip could be dangerous and a bad differential bearing will lead to further, unrepairable damage.
Good luck

[opelbits]

Here is a question....is there a source for good quality, correct c-clips?

[DriveCrash]

I just got off work, and i'm getting ready to go take the jug off the back, see what the clips look like.

Thanks again for all the advice. The reason I asked about the final drive, was that I didn't want to put all this work into the rear end if i was going to change it later to achive highway speed better. But, I had not thought about the fact that the 1.9 would not have the low end torque to pull it along at 60mph without being 3k rpm range. The engine is pretty stock. Even still has the solex carb.

I'm going to try to get my dial indicator mounted to see if the end of the half shaft is bent, and thats what is causeing the tire wobble. Surely it is not normal for the tire to look like it's on a bent rim when you have the axle off the ground?

I've been working on cars as a plain jane mechanic for years, and this opel has me feeling like a beginner all over again.

[OpelJim]

Originally Posted by DriveCrash I just got off work, and i'm getting ready to go take the jug off the back, see what the clips look like. Thanks again for all the advice. The reason I asked about the final drive, was that I didn't want to put all this work into the rear end if i was going to change it later to achive highway speed better. But, I had not thought about the fact that the 1.9 would not have the low end torque to pull it along at 60mph without being 3k rpm range. The engine is pretty stock. Even still has the solex carb. I'm going to try to get my dial indicator mounted to see if the end of the half shaft is bent, and thats what is causeing the tire wobble. Surely it is not normal for the tire to look like it's on a bent rim when you have the axle off the ground? I've been working on cars as a plain jane mechanic for years, and this opel has me feeling like a beginner all over again.

NEW 69 bearings are available from Germany BUT they are Extremely EXPENSIVE.
Best to just swap out an entire rear end
Remove the differencial cover and clean the gears out with a can or two of WD 40 Get a new gasket for the cover and fill with a good gear oil with Lucus oil stabilizer added to it.
Then you should be good to go for more than 6000 miles without servicing the rear end again.

[DriveCrash]

Ok, so here's what i've found..

The clips look strong and intact, all the main gears in the axle seem solid, except there is a fair amount of play between the drive gear (from the driveshaft) and the main planetary gear (name? the big gear that turns the axle) However, there is alot of slap in the limited slip gears. Not enough to think it's going to break, but enough that it would explain some of the noises when combine with the play in the main gear.

The end play is not as bad as I thought. The driver side does have enough play to see visable movement, but not more than 1/16th of an inch if that. I assume this is normal from wear on the retaining clip and mateing surface.

The wheel bearings make a bit of noise too when spinning the shafts. After looking at the fill plug on the axle, how the hell do the bearings get lubricated? The half shafts are higher than the fill plug??? How hard are they to remove and clean (the bearings & half shafts).. And how do you make sure they are getting the proper lubrication?

The big problem seems to be completely in the driver side tire whooble. The half-shaft is bent at the lugs. I dont know how that happened, but it's definatly not cool. Anyone know where i can find an old 69 - 70 axle with a good halfshaft? =P

I think i'll do what I can to baby this back together until I can afford a different axle if I do indeed need to go that route. Sad to say this car IS my daily driver until I can get enough money to get some junker to drive.

[opelbits]

I can see what I have. If you just want a halfshaft, if I have a good one, I could ship it to you.

[DriveCrash]

Originally Posted by opelbits I can see what I have. If you just want a halfshaft, if I have a good one, I could ship it to you.

I might be able to make the drive up to st. L, my friend offered to take me. Wouldn't have room for the entire axle in the car though =) That would be a HUGE help though, as it seems everything else is ok, other than the torque tube bearing and all that mess being screwed up. But the half shaft is defintly bent.. Unless the play in the main gear and the drive gear is not good, then I might have issues.

Whats the best weight gear oil for the older rear axle? 85-140? or is that too heavy? I cant afford redline atm, so I'm looking at "normal" brands for now. Any suggestions? (keep in mind this is not for race application... I drive slower than my grandmother)

[DriveCrash]

Originally Posted by matl59 You could still be getting noise from your torque tube mounts. You mention replacing them with intacked ones but I'd urge you to replace with new along with the doughnut inside the end of the tube. Mine were intacted but I had a banging noise. Once I replaced them with new the noise was gone.

I think thats the majority of my problems, but I started looking too closely at the rear axle thinking problems could exsist there. I haven't had the car for that long, so I really dont know the condition of a lot of the car, and I like to try to find problems before they become disasters. From what I priced on OGTS it looks like the total bill for the bushings, bearing and all the rest of the rubber.. is 162.50? Does that sound right?

[opelbits]

Drive-
I'll send you a pm.

[GordonW]

Originally Posted by Anonymous D Installing a set of Kadett 3.18 gears into a GT (that has anything less than 130hp,or a 2.4L engine at the least) is a bad idea.

Some 1973 GTs CAME with the 3.18:1 differential. I know, I used to OWN one.

Came with a bad engine (the near-universal blown oil pressure sending unit struck again)... but fortunately, I was able to find a very good 1970 1.9 from a station wagon (high compression), so it was able to pull the 3.18:1 gears quite effectively. In fact, with carb re-jetting, some intake polishing, air cleaner mods, and a few ignition mods, I could get it all the way up to 6100 RPM in 4th gear on a long pull on a deserted road! With 185/70/13 tires (just over 22.5" tire height), according to my calculations, that's right at 132MPH!!

So, yes, if you have a high-comp engine, it'll probably have enough torque to pull a 3.18 differential...

Regards,
Gordon.