91' RIVIERA- SUBFRAME/CRADLE BUSHING

[Guest RIVIERA1991]

Hello, Im new to the site and would 1st off like to take the opportunity to say hello to all the members and moderators. I have a 1991 buick riviera. I have had for several years and it is an on going project. I like in Indiana and the salt and snow are hard on a vehicle.

With that being said, Im in the process of replacing the subframe/cradle bushing and bolts. The bushing is completely gone and it is very dangerous. Ive take the car to the shop and they want $635 to complete the job. - yeah, when pigs fly theyll get that much money from me for that job. I have a friend who is a mechanic and willing to help me out. Ive done most the work on this car so Im not timid at jumping into the project my self.

I was wanting to know if anyone can point me in the direction to find the correct bushing and bolts. I called the dealer and they only have the lower bushings and bolts. Is there a replacement that will also work in this instance. Please advise. I want to get this thing taken care of before the snow is on the ground. Lord knows what added stress is given to the car during the sub temperature months.

Thanks again in advance and any suggestion and help is greatly appreciated.

Riviera owner (1991)

[Rivieraman]

Riviera 1991 Welcome to the group you may also want to check out www buick forums dot com. there are more guys there with your year cars to help

[Barney Eaton]

You can go to the Reatta discussion and do a search, your '91 Riviera used the same mounts and subframe as a Reatta. I believe you will find part numbers etc.

[NTX5467]

As you mentioned "snow on the ground", I suspect you might be in the northern regions of the country. What I'm going to suggect is a little different than what you might find, but considering how subframe bolts can be a hidden time bomb of sorts, I feel it's a good upgrade to perform.

The normal "SAE" subframe bolts are normally Grade 5, which is the normal level of hardness for most bolts. What will make them unique for their particular application is their head configuration. It's my suspicion that your vehicle will have metric subframe bolts, which should be a similar Grade 5 in hardness. They should be "flange head" bolts. Any shapes and configurations on the end of the threads is there to help get the bolts in the hole on the assembly line for expedient installation.

What I did on my '77 Camaro was get into the GM Standard Parts Catalog and, using the specs for the normal bolts listed in the parts catalog listing, find a similar bolt with Grade 8 hardness and the same configuration of "flange head" (looks like it has a built-in flat washer under the bolt head). I believe they also came with the black oxide coating, too. In more current times, you might need to check with local bolt dealers to find such a Grade 8 metric bolt with the correct anti-corrosion coating.

In any kind of "clamping" situation/interface, there is usually one part of that mechanism which will be the weak link, by design. But the weak link is usually related to maintaining the threads in a hidden caged nut the bolt screws into, for example. Much better to have the threads on a softer bolt go away than to need to replace the threads on the Grade 5 caged nut, with all due respect . . . that "repairability" issue. Still, though, I would recommend you consider upgrading the subframe mounting bolts to Grade 8.

Just a recommendation, though.

Just some thoughts,

NTX5467