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The bushings on my car were aftermarket and the inside diameter of the sleeve was larger than stock. I am converting to poly bushings which have the same inside diameter sleeve as stock. The bolts on the car before won’t fit as they are too large in diameter. I was looking to order some bolts from aircraft spruce but am a little fuzzy on the sizing. The stock bolts are 12Mx1.75x80mm for the upper A Arm to chassis brackets.

Converting this to AN seems to be 12M=AN7.

80mm = 3 5/32 so I am thinking -31 (3 7/32) is the closest in the aircraft spruce chart.  

I’m getting a little tripped up in the what the grip size of the bolt should be. Should the grip run fully through the bracket and bushing? Seems like it should so the threads don’t chew through the bushing. I have included a picture of a metic bolt that is 12Mx1.75x80mm but as you can see the grip isn’t as long as the the width of the bracket and bushing (2.35”). Am I overthinking this? Thanks.




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If your car has been using a bushing bolt larger than OEM, then the holes on all of your a arm mounting brackets would also need to have been enlarged to accommodate the larger bolt.

Without some corrective bushings to accommodate the smaller bolt in the enlarged mounting bracket holes, I see a problem with you returning to 0EM diameter bolts.

or am I missing something?


Last edited by lf-tp2511

This might be a stupid question but is it possible the bolt hole of the a arm brackets can standardly accommodate the 1/2” bolt. It seems odd that someone would enlarge the holes to 1/2”, a lot of work to accommodate bushings. The bushings that I replaced appear to be the poly graphite with the hex inner sleeve which were available from at least Precision Performance. Thanks.

Thanks David, I should’ve been more clear. I don’t think the 12 mm holes had enough OEM slop to allow the larger bolts without them being enlarged. A simple ten second task with a half inch drill bit chucked into a cordless drill;  and a lazy and ill advised action that will forever plague and perplex future owners until it is returned to OEM  dimensions.

as for the bushings being from Dennis Quella I agree (not the now-defunct Precision Proformance run by the late Bob Byars). Dennis is the only vendor I am aware of that has the hexagonal center section.


Thanks, guys. I think I just had to go through the stages of grief to suck it up. I think David is correct in that I just need to opt for bushings with the 1/2” bolt. It probably isn’t the end of the world. I might be able to pick some up from Energy Suspension. I will measure it out tomorrow.

David, to your question about why in am changing the graphite bushings; somewhere in the car’s past only  three wheels were updated to the graphite bushings. For some odd reason the passenger rear was something else, and deteriorated. The whole rear suspension is being gone through so I thought a new set of poly bushings would be easy.

Larry, I certainly don't consider enlarging the suspension mount bolt holes to 1/2" "mutilation", if it was done as part of an overall improvement. Obviously, Dennis Q.'s bushings do indeed have a 1/2" ID and metric OD. I can see Dennis doing this because he's always complaining about the Pantera's junk metric hardware.

FYI, Dennis advises changing the steering arm to spindle mounting bolts from M10 to AN7/16". Apparently, there's a problem with the M10 bolts breaking!!! As a long time Pantera owner, that's news to me! On the other hand, there's likely no one who's seen more Panteras than Dennis, so if he says it's a problem...

Shashi27, there are two obvious, easy solutions to your bushing problem. The first being, just buy a new set of bushings from Dennis; the same ones as on the car now. The second being, buy whatever bushings you want and ream the metric center hole out to 1/2". As the amount of material being removed is so minimal, I can't see it causing a problem.

Last edited by davidnunn

F7C3FB1D-A44F-40A2-BF6A-A4B99F23F97ALooking at the poly bushings, I don’t think I need to ream the bushings, I think I need to have the sleeves cut to a larger inner diameter, a thinner sleeve.

BTW, “the other Larry” said the chassis holes are 12.3mm (.480”). So there is a little play already there. That still doesn’t account for my car accepting the 1/2” bolts though.

I also left a van with Dennis to see if he can let me know his thoughts.

Will keep you posted. Thanks


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I was able to get in touch with Dennis. He doesn’t make the bushings anymore but did say they were 12M.

I also connected with Larry Stock who is working on my uprights and he didn’t think the larger size hole was significant to make much of an issue as the the bolts are cranked down pretty tight on the chassis. For now I’ll use the 12M bolts, then get it properly welded when the car goes in for paint.


So you will be using the new bushings that have a 12 mm ID and the OEM-correct 12 mm bolts.

but using those 12 mm bolts and 1/2 inch bracket holes will, as you know, leave the potential for movement. I do not believe the forces at work in the suspension of a 3000 pound car can be overcome by tightening the 12 mm mounting bolts.

I believe you could use the adapter bushings I posted earlier without actually welding them in place. For that action I believe tightening the bolts would certainly be sufficient, and safer than allowing your suspension to have 16 points of potential movement  

I would certainly advise welding them in place at the earliest convenient moment.


Last edited by lf-tp2511

It is critical that you weld the step washers to the suspension mounting tabs as you’ll be relying on the washers for strength. The inserts that reduce the ID of the holes will only be 0.013”, which is paper thin. Any movement and they’re gone. Have you considered just welding up the holes and re-drilling them to 12mm? Welding on those tabs won’t be easy as some of them aren’t too accessible. Even cleaning them up for welding won’t be easy. I still think the easiest way to solve your problem is to enlarge the holes in the new bushings to 1/2”.

Last edited by davidnunn

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