Do I need new strut mounts?

[johnbell47]

I am doing my dead level best to make my Early 260 into a boulevard cruiser. It is a hybrid, with a mild, 350-350 chev, I have queit matted, 4 mufflers, two glass paks up front and two turbos out the rear with 2 1/2 pipes and a X pipe. Drone is manageble. Driveshaft is aligned. (major good! vibe stopper) All wheel bearings disassembled and greased, with new parts as needed. new rubber (stock) suspension parts, No Urethane anywhere, and all parts replaced. New tie rod ends, ball joints, complete brakes with new rotors, shoes, etc. This car is pretty smooth. BUT! it still has an anoying vibration that you can primarily just feel in your arse, or

through the seat. I pulled the struts out during the rebuild, I don't know what they are, but they were stamped "Made in Venezula", they felt good, so I put em back in. I was feeling kinda poor about then due to all the other parts, so I took a short cut. Anyway, I have decided to repalce all the struts with new. I am not going to shortcut this time, pulling struts is a pain in the arse and I ain't doin this again!! My question. Looks like strut mounts are at least 57.00 or so apiece, best price. Mine look good but they are 40 years old. Does the rubber go bad? Will it make a diff? Anybody been here before? What is the absolute best strut for a creamy smooth ride? Thanks!!!

[pbarcher]

I also replaced all the bushings, bearings, u-joints, etc. in my '73 with OEM rubber, including the strut mounts. I'm the original owner and the car is as smooth as when I bought it 39 years ago this month. You're on the right path so just wait until you can afford doing the suspension the right way.

I also added Dynamat sound/vibration/heat insulation throughout the entire interior, which made a huge difference. It was time consuming but well worth it.

Peter

[johnbell47]

I think I have the sound thing down, I quiet matted the entire bottom, doors, roof, etc. and added 1/2 camper pad foam to the headliner and the rear floor. that helped a lot! but still, my question is should I spend the 250.00 bucks on the mounts or not? I am leaning toward KYB G2's for the struts. If you have any better suggestions,,,please let me know!! thanks for the reply. By the way,,Were these cars quiet when they were new?? You would know, if you can remember that far back..I can say that since I'm 65 myself..I can afford this, I just have to justify it!!!

[Carl Beck]

There is a Bump Stop in the Strut Mounts in the 240Z's - I'd guess that the 260Z's were the same. The Bump Stops decay/dissolve over the decades - I always replace them, but the Strut Mounts very rarely need replacing.

I doubt that replacing the Strut Mounts will get rid of the vibration you feel.

When new - the cars were smooth - but measured by todays standards for new cars - the Z's weren't nearly as quite. In addition to wind noise - the body design - ie. the hatch back coupe - becomes an megiphone for road noise as the struts are bolted directly to the body on relatively hard rubber/steel mounts. I'd say that tire selection in terms of size, tread patterns etc play the largest roll in providing as smooth and quite a ride as you can get.

FWIW,

Carl B.

[johnbell47]

I have nice centerline 15 inch wheels and Falken tires, they are bigger than stock but not by a whole lot. I know I pumped the tires up to 32 P.S.I. and the car rode like a log wagon. I think I have them at about 26 now and it is lots better, wonder what a good pressure would be? Tires do not look low at 26. As I said, the megaphone effect went away when I added the 1/2 inch Walmart Camper pad to the roof and rear deck, that really was a good cheap deal, the Quiet mat was not cheap and did not do the job. I have the care quiet enough, its just that niggling little vibration. I don't have bump stops. But they really don't come into play unless the suspension is bottomed out, do they? I was under the impression that if you used a strut cartridge instead of the stock rebuildable strut, you didn't need bump stops. Am I wrong? Anybody want to wade in on the KYB's??

[Zed Head]

I think that the comments about the bump stops were made because you asked specifically about the strut mounts. You're right, you won't know that they're there unless you hit a large bump.

When you said that you had the drive shaft aligned, what did you mean and how did you do it? The SBC swap usually leads to having the nose of the differential too high. Many people use an "RT mount" (design by Ron Tyler), a redesigned differential nose mount for higher strength and less nose movement, which also lowers the nose to get proper alignment. If the front and rear u-joints aren't on parallel planes, you'll get a buzz.

[ConchZ]

I think that if your strut mounts aren't falling apart, then you don't need to replace them. I lived on a small island when I redid my suspension, so I ordered pretty much everything I thought I would need, including strut mounts, just so I would have it. The new strut mounts looked just like my old ones, which were probably original. One thing I didn't order was the spacer that goes between the spring perch and the strut mount. Originally rubber, they disintegrated quick. Go with poly here, just because the part takes a lot of wear. MSA sells them, or you can make some out of a poly bump stop by cutting it down.

As for KYBs, I have them, but I also have the Eibach springs and poly bushings. The ride is rather rough, but I don't think its because of the Eibachs.

[johnbell47]

As to the drive shaft alignment, I have the RT mount and have aligned with a laser on differential flange and on the rear of the T-5 transmission mount. yes, the nose of the diff had to come down 7/8 of an inch to get the lasers to match. That was a major issue on "Buzz". This is a different issue, its not as consistent as the drive shaft buzz, its more like a suspension related jiggle..(is that a word!) I don't remember any rubber parts other than the big rubber biscuit mount at the top with the three bolts and one in the center for the strut cartridge. I may be missing the rubber between the spring perch and the strut mount!! I have a factory manual, which is of absolutely no help due to not even mentioning strut cartridges anywhere, same with the Haynes manual. I guess I'm going to pull it apart and see if I can figure out what is missing or wrong. I'm gonna go look at the MSA catalog now!

[johnbell47]

O.k, went to MSA and did not see the rubber part between the spring perch and the top insulator mount, went to the haynes manual and it ain't there either...? Are you sure there's another piece. I remember now using the Haynes manual due to the Datsun shop manual being so out of date..

[ConchZ]

http://www.thezstore.com/page/TZS/PROD/23-4166 or http://www.zcarsource.com/upper-strut-spacer-rear-70-78-new_8_54060_48618.html

There used to be a diagram in the blackdragon catalog, but I can't find it there anymore. Maybe someone can post it for you. Without these little 1/2" spacers, you get a slightly sagging rear end.

[Zed Head]

Weird, I never realized that those were in there, I guess they're kind of buried. They're shown in the RA section of the FSM as a spacer. Might explain the quarter inch mismatch on the rear of my car.

Edit - Found a diagram and part number. http://www.carpartsmanual.com/datsunS30/DatsunZIndex/Axle/RearSuspension/tabid/1731/Default.aspx

Edited September 3, 2012 by Zed Head

[johnbell47]

I see them in the diagram, I don't believe I have these in my car. I put it back together like I found it though, so they weren't in there to begin with. Are these rubber?? In the FSM I have it does not address rear struts, it just refers you to the FA section to service. Reckon that these spacers take the place of the strut bearing in the front strut? Same place, right? I think I'm gonna quit fooling with this damn thing and just go ahead and order these, some new KYB's and new strut mounts too. Won't be too bad if i just do the rear and then do the front a little later.