January 13, 1999
I've seen a number of clever and often more complex solutions to the problems caused by the transmission support in 1800 series cars, but I recently implemented an extremely simple one and I am very pleased with the results.
as the story goes...
Last year I finished building a new B20 for the 1800E I put together. I put the whole thing together, and got her started after a couple of days of dinkling with the distributor and some failed injectors. [Got a dozen or so used ones, of which maybe seven or eight are good. Of course, I would put in the three bad ones to begin with (they looked better that the others, anyway)].
After a very, very hectic week of last-minute planning and an almost-failed search for a front end alignment (I had rebuilt the front end, removing the center crossmember to rustproof it and put in new bushings, etc.), I drove the car down to Rhode Island from Boston, where I was going to store it for a month before I moved to San Francisco.
On the way down to Rhode Island, in heavy traffic, I noticed a persistent thumping noise under the car whenever I started up in first gear. Not that it really bothered me that much, the car was running so well, and I was more concerned with the oil pressure than anything else.
Anyway, I come back a month later to drive the car to San Francisco. And to make a long story short, I drive the car every day, and, as much as I was pleased with the overall performance, the thumping noise was really driving me mad. It did prevent me from any over-enthusiastic accelerating.
So, of course, it's the transmission support bushing, the Achilles' heel of the P1800. I put in a brand new mount when I rebuilt the car, but the engine still sags so far back, the drive shaft was thunking violently going up hills. I was scaring the crap out of my passengers.
So I shimmed the bushing with big fender washers. It was a bit tricky squeezing the whole thing back together, but I haven't had a problem since. I guess eventually it's going to sag down far enough that it will start all over again. The next time, I'll get out the welding torch.
Is this a valid fix? I have been over this in my head a bunch, and the long-term side effects would seem to be minimal. Comments?
Brian O'Kelley
Brian - Congratulations on the success of your project. I have used big fender washers to shim motor mounts with acceptable results, but not lately. It seems that some motor and transmission mounts are better than others, and over the years the ones I have purchased from Volvo have been pretty sorry until recently. They may have found a way to improve the rubber, because the last set I bought has done very well, and looked firmer right from the start. Even after two years, they don't look squashed.
IPD recommends using the transmission mount from a Volvo 164, which is the same as the motor mount on the 164. I tried this, but found that though it worked, it was not a perfect fit.
The original part number for the transmission mount on the 1800 is different for M40 and M41 transmissions, and also is different from the motor mounts, which look similar. It is possible that Volvo has merged some of these part numbers, but if not, you should make sure you are using the proper mount. Also, be sure the motor mounts are in good condition. Sloppy motor mounts can make the transmission mount wear out quickly. -Glenn.