torsion bolt size

[TopgunZ521C]

Anyone know off the top of their head the size of the torsion bolt and nut asking for a friend 2014 Z521C ?

[Firebone]

I tightened mine the other day....15/16.

[TopgunZ521C]

I'm asking for the designation of the thread and length and diameter for upgrading to a grade 8

[Firebone]

Sorry I can’t help you there, didn’t realize what you needed.

[champ223]

I’d like to know the same. Maybe Basscat boats will chime in here. They change theirs to a grade 8 on their trailers.

[TopgunZ521C]

for everyone needing this info it is as follows grade 8 (Bolts) 5/8-11 x 4 inch (Nuts) 5/8-11 nylocks (Washers) 5/8 flat washers / Note all hardware is yellow zinc coated standard bolts from the factory are grade 5 the difference is grade 8 has 150k Lbs tensile stregnth per square inch before it breaks as a grade 5 has 120K Lbs tensile strength per square inch before it breaks. This might explain why the grade 5 bolts are stretching or having problems hope this helps everyone.

[Bass Cat Boats]

yes, this explains our position on Grade 8 bolts. The bolts provided by Dexter are Grade 5 and we do not use those. We buy our own Grade 8 and have since 2019 model year, so everything 2020 and newer is Grade 8. We did this in desperation as idler arms failing when impacted were numerous. Rolling down the road the forces are not significant, hitting a curb, culvert, pothole or a vehicle hitting a tire from the side can be an issue.

The situation is exponential pressure as the idler arm spline to spindle is an extended arm, acting as a lever when those forces occur. The assembly design is open to flex something and the weakest link was apparently the Grade 5 bolt. What else could allow stretch? We have seen idlers oval on the spline side, and spindles bent also. The oval in the idler spline radius set indicated to us bolt failure. It was common and why on earth should a bolt need tightening when it’s set at 150 lbs of torque.

Obviously we also are in question as to whether the provided Grade 5 bolts are actually what they indicate from the vendor.

BCB

for everyone needing this info it is as follows grade 8 (Bolts) 5/8-11 x 4 inch (Nuts) 5/8-11 nylocks (Washers) 5/8 flat washers / Note all hardware is yellow zinc coated standard bolts from the factory are grade 5 the difference is grade 8 has 150k Lbs tensile stregnth per square inch before it breaks as a grade 5 has 120K Lbs tensile strength per square inch before it breaks. This might explain why the grade 5 bolts are stretching or having problems hope this helps everyone.

[bloodman]

yes, this explains our position on Grade 8 bolts. The bolts provided by Dexter are Grade 5 and we do not use those. We buy our own Grade 8 and have since 2019 model year, so everything 2020 and newer is Grade 8. We did this in desperation as idler arms failing when impacted were numerous. Rolling down the road the forces are not significant, hitting a curb, culvert, pothole or a vehicle hitting a tire from the side can be an issue.

The situation is exponential pressure as the idler arm spline to spindle is an extended arm, acting as a lever when those forces occur. The assembly design is open to flex something and the weakest link was apparently the Grade 5 bolt. What else could allow stretch? We have seen idlers oval on the spline side, and spindles bent also. The oval in the idler spline radius set indicated to us bolt failure. It was common and why on earth should a bolt need tightening when it’s set at 150 lbs of torque.

Obviously we also are in question as to whether the provided Grade 5 bolts are actually what they indicate from the vendor.

BCB

Finally an explanation I can understand. Thank you!!! Now on to getting 4 bolts

[bloodman]

for everyone needing this info it is as follows grade 8 (Bolts) 5/8-11 x 4 inch (Nuts) 5/8-11 nylocks (Washers) 5/8 flat washers / Note all hardware is yellow zinc coated standard bolts from the factory are grade 5 the difference is grade 8 has 150k Lbs tensile stregnth per square inch before it breaks as a grade 5 has 120K Lbs tensile strength per square inch before it breaks. This might explain why the grade 5 bolts are stretching or having problems hope this helps everyone.

Thank you!!!!

[TopgunZ521C]

Bloodman no worries just wanted to post the correct information so everyone could recieve it glad it was helpful.

[Javelin387]

When replacing them, do you have to jack the trailer up or anything? Or is it as simple as loosening and then putting the new bolt in? Will the Spindle move? Any help here guys will be awesome, then John can sticky this at the top of the page. A huge thank you to Bass Cat Boats for clarifying what issues there are and how to remedy them.

[Bass Cat Boats]

We would Jack up the frame and replace the bolts so the splines take a good seat when you torque them.

[TopgunZ521C]

Basscat boats thank you for the input as indicated above the grade 5 bolts could be a sub par bolt as well I have ordered and recieved mine from a bolt specialist McMastercar.com also when assembling it wouldn't hurt to apply red locktite to the bolt threads to prevent any further issue.

[Bass Cat Boats]

https://basscatstore.com/torsionboltkitgrade8.aspx

This should be what your after.

BCB

[TopgunZ521C]

https://basscatstore.com/torsionboltkitgrade8.aspx

This should be what your after.

BCB

10-4 exactly ive already done mine and back on the road thank you BCB for the response others will find this helpful along with 242 red locktite @150 ft lbs they will be good.

[Rudeman]

https://basscatstore.com/torsionboltkitgrade8.aspx

This should be what your after.

BCB

Just tried to order and got a pop-up message stating that they can't ship to my location. I guess there are no diplomatic relations between Arkansas and the Democratic People's Republic of Illinois...haha. Researched and purchased from McMaster-Carr; should arrive this Tuesday.

Nevertheless, thanks for the information; it was helpful in ordering the correct hardware.

[Bass Cat Boats]

Shouldn’t need the LokTite with nylon nuts.

BCB

[OH_Ranger]

Those bolts are only $2.40 each at McMaster. McMaster is not really known for low prices.

[XingEyeballs]

[Bass Cat Boats]

We didn’t see $2.40 on this length in coated bolts at McMaster and no doubt our vendor is searching a quality product for us. This doesn’t mean McMasters is not high quality as we have never had an issue with their parts. We did see the disparagement in price between lengths.

Saving money here on an unknown imported quality (not meaning McMaster) would seem like a questionable decision.

BCB

Those bolts are only $2.40 each at McMaster. McMaster is not really known for low prices.