Trillium 4500 frame bolt size type - Fiberglass RV

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Old 10-25-2013, 09:07 PM   #1
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Trailer: Trillium 4500
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Trillium 4500 frame bolt size type

Hi everyone and thanks for all the great info provided on this site. I am thinking of replacing the corroded bolts on our '78 Trillium with stainless and was hoping someone could give me an idea of what they have used in terms of head type, size - one post I did read mentioned 5/8" - and what length. I was hoping to check sources and availability before I started messing with the originals in case they snap when attempting removal. I tried google searching the forums but could not find any results. Thanks!

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Old 10-26-2013, 08:34 AM   #2
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Larry C Hanson's Avatar
Name: Larry H
Trailer: Trillium
Posts: 327
Trillium mounting bolts?

Hello Fred,

Just remove the bolts and then determine the size.

I believe the bolts on my 1978 1300 were 5/16".

Trillium Body Mounting Bolts

Good Luck, Larry H

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Old 10-26-2013, 08:45 AM   #3
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Thanks for the reply Larry. Yes, I did see that post you linked to and mis-typed 5/8" instead of 5/16" in my original post. I do intend to remove the existing bolts and check when I have the chance and it's a little warmer. I just wanted to get an idea of the type of head - hex or carriage or does it matter? - and the length so I could check on local and online availability of stainless replacements. Thanks again! - Fred
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Old 10-28-2013, 09:37 AM   #4
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Name: Dave W
Trailer: Trillium 4500 - 1977, 1978 (2), 1300 - 1977, 1973, and a 1972
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I believe they are carriage bolts. I had Trillium / Out Back install mine backwards. that way the threads are inside, where they wont rust. I had to cut the bolts flush with the nut so the port a potty would fit under the gaucho.
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Old 10-28-2013, 01:48 PM   #5
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Trailer: Trillium 4500
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frame bolts on 1978 Trillium 4500

Thanks David. I did finally manage to get one bolt off today. It is size 5/8" and 2 1/2" long carriage bolt with 3 lock washers and one nut. I will replace it with stainless and get extras sets for replacing the other bolts when I get to them. It was not as corroded as I originally expected so I feel no rush to replace the others. The problem with removal was that the square anchor plate with square cutout for carriage bolt was not secure in the interior floor so it would spin when trying to undo the nut from outside. I soaked the bolt from underneath with WD40 yesterday. Today I secured the bolt with a vise grip on the threads while I unscrewed the nut and this did a number on the old bolt which didn't bother me as I knew I was replacing it anyway. I plan to replace with a stainless hex bolt and oversize washer that someone can hold the bolt head tight with a wrench or socket from inside while I tighten the nut and lock washers from underneath. I hope this post helps others researching Trillium 4500 frame bolts.
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Old 10-29-2013, 05:19 PM   #6
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Looks like I miss-typed the bolt size once again. It's 3/8" not 5/8". Sorry. The length is correct - 2 1/2". My frame has tabs with holes for the bolts welded on to it. I replaced the carriage bolt with a hex lag bolt which had just enough threading for the nut to tighten with 3 lock washers - as were on the original bolt. I did this using the original square anchor plate inside and with a large 3/8" washer on top of that and then I dropped the bolt in. After I hand tightened the nut with 3 lock washers from underneath I put a vise grip on the nut and braced it against the vertical surface of the frame. Then I went into the trailer and tightened the entire assembly with a wrench on the bolt head while the nut was held from spinning by the vise grip underneath. So, I didn't need a helper. I also put some automotive adhesive/sealer between the anchor plate and floor inside just for good measure.

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