TH400 trans mount bolts

[496bb]

Noticed I am missing one of the two bolts that go through the trans mount on the rear of my 87 R20 Burb's th400. Can anybody help me out with the bolt size/length needed so I can go grab one?

 

[Ricko1966]

I'm pretty sure there were 2 different possibilities,best bet is pull the one you have and match it. If I just wanted to buy something and go home with too much. I'd buy a 7/16th coarse 7/16th fine and an m10x1.5 all 1.25 long.

 

[Radiohead]

Bet it's metric.

 

[DoubleDingo]

I'm pretty sure there were 2 different possibilities,best bet is pull the one you have and match it. If I just wanted to buy something and go home with too much. I'd buy a 7/16th coarse 7/16th fine and an m10x1.5 all 1.25 long.

^^^^^THIS^^^^^

 

[DoubleDingo]

Bet it's metric.

Probably

 

[Rickf]

1) I'd get some tools,
2) go to a local hardware store
3) remove one of the remaining bolts
and find something the same size.
But that's me.

 

[Old Guy Bill]

I believe my TH400 mount uses 7/16-14... but it's a '70s unit..

 

[496bb]

That’s what I was thinking too, just wondering if someone knew offhand. 87 was a real mixture of SAE/metric.

 

[496bb]

1) I'd get some tools,
2) go to a local hardware store
3) remove one of the remaining bolts
and find something the same size.
But that's me.

Wow, one in every group I guess

 

[DoubleDingo]

Wow, one in every group I guess

No different than post #2 except for the wording.

 

[Radiohead]

That’s what I was thinking too, just wondering if someone knew offhand. 87 was a real mixture of SAE/metric.

'79 ain't no picnic either. I get tired of the trek back and forth to the toolbox for different basis tools. At my shop, it's a trip up and down stairs outdoors.

 

[DoubleDingo]

'79 ain't no picnic either. I get tired of the trek back and forth to the toolbox for different basis tools. At my shop, it's a trip up and down stairs outdoors.

Even my '81 is a mix of imperial and metric. First time I started tearing into things with my imperial tools and couldn't find a size that fit, I knew it was similar to my '91 Cherokee, where I needed a set of tools with both. My setup sounds similar to yours except mine is not up and down stairs, it's a 160-170 feet walk one-way to the tools. That's why I carry a small set in each vehicle, then only the specialty stuff requires "the walk". Even on my Jeep, I had one bolt missing on the trans-mount, went to the hardware store that carries a ton of bolts and screws and still couldn't find an exact match the other. It was a metric bolt, but it has an 11/16 imperial head and that measures 17.4mm, odd duck indeed.

 

[Sad Sack]

Even my '81 is a mix of imperial and metric. First time I started tearing into things with my imperial tools and couldn't find a size that fit, I knew it was similar to my '91 Cherokee, where I needed a set of tools with both. My setup sounds similar to yours except mine is not up and down stairs, it's a 160-170 feet walk one-way to the tools. That's why I carry a small set in each vehicle, then only the specialty stuff requires "the walk". Even on my Jeep, I had one bolt missing on the trans-mount, went to the hardware store that carries a ton of bolts and screws and still couldn't find an exact match the other. It was a metric bolt, but it has an 11/16 imperial head and that measures 17.4mm, odd duck indeed.

Years back, way back, starting in ‘79 the misery started and then I believe (maybe) it was engine SAE and the rest metric. Sucked to have to buy more tools when wages weren’t even $3 an hour. Back then tools weren’t cheap. The 79 Monte Carlo I learned this from back then was an irritating experience.

 

[KWMECH]

Probably have it sorted by now but the Metric 10mm size is going to be a 1.5 pitch 25 or 30mm long, not 1.25 pitch. GM never used a fine thread in aluminum. 1.25 pitch is an asian thing