KLR Subframe Mod

By: AdvWisdom
Title: KLR Subframe Mod
Sourced From: advwisdom.com/a/klr-subframe-mod/
Published Date: Mon, 20 Jul 2020 01:13:39 +0000
KLR650 Subframe drill thru step by step walkthru

Enclosed is a step-by-step process for the replacement of the stock KLR650 �sub-frame� fasteners. 2x kits are available. I did not know both kits accomplish the same task, so I ordered both. One kit is a fastener replacement (the $5.00 kit). The other kit is the �drill thru� install (the 24.99 kit). I will illustrate installation both kits. The intent of the upgrade is to strengthen the sub-frame joint with stronger cap head (allen key) style fasteners. The upper sub-frame bolts are known to fail. This will “load-up” the lower sub-frame bolts and stress the fuel tank connection, wire harness, and exhaust system. This upper sub-frame fastener failure could be catastrophic to the rider and/or cause extensive bike damage. Both kits are available from: www.arrowheadmotorsports.com
I would recommend reviewing these threads prior to starting this mod: http://klrworld.com/forums/index.php/topic,721.0.html and http://klrworld.com/forums/index.php/topic,878.0.html
5.00 kit
The $5.00 kit will swap out the 4x sub-frame 10.9 grade fasteners with 12.9 grade fasteners of the same size. The shear strength capability, of the $5.00 kit fasteners, is 20% greater than the stock OEM sub-frame fasteners.
24.99 kit
The $24.99 kit will have the user replace the 2x upper sub-frame fasteners with a single larger, stronger single fastener. The 2x lower sub-frame fasteners will be the same as the $5.00 kit. The upper sub-frame bolt will be the 12.9 grade 10mm size. This modification will effectively double the strength capability of the upper sub-frame load bearing joint. The joint will now be a �double shear joint� (that is a good thing).This will minimize load transfer eccentricities, eliminates the fastener transition failure mode.

Start with a little research. Articles, clips, lessons learned, fastener data collected for summary discussion.

Kits as delivered. Lower baggie is the 5.00 kit the upper baggie contains the 24.99 kit

Cap fastener head 12.9 stamped on manufactured head. These are the strongest metric (non-aviation) fasteners available.

size M8-1.25 metric coarse

length measured at 30mm

that�s the size for all 4x fasteners

Instructions included with the $5.00 kit

Put bike on level lift, and strap it down.

Do not work from kick stand.

start to uncouple fuel line from tank

side panels

tank attach fasteners

tip here: drape rag at frame spine/tank gap frame here. That way, when manipulating tank off frame/tank pucks your frame spine finish will not be abraded by the tank!

all the stuff removed. Note more detail of these items removed can be found here: http://klrworld.com/forums/index.php/topic,950.0.html

I started from left side, lower sub-frame bolt. Swap out one at a time, so holes stay aligned. 12mm socket. Rotate counter-clockwise. Use a 6 point socket. Mine came off easy.

stock and kit replacement. Both same size.

tools for install 6mm allen head socked for torque wrench

add red locktite and tighten.

torque to 18 ft-lbs. If doing the drill thru upper frame mod don�t torque yet, just tighten

add OEM fasteners to all KLR replaced fasteners collection cup

getting full here…whew! Repeat process on opposite lower sub-frame side

lower sub-frame installed

upper subframe �cap style� fastener to remove

Upper frame fastener as removed. These were factory installed with loc-tite, as shown. Mine came off easy.

red loc-tite these.

install to same torque as lower sub-frame fasteners (18 ft-lbs)
All done with the $5.00 kit. The shear strength of the joint has increased by 20% for a $5.00 cost and the satisfaction that they have been installed properly!
Now for the $24.99 kit…I�ll focus the rest of the pitch on the upper �drill thru� process. This is tricky. First start with the bike on stand, seat, tank, panels are off.

Drill thru instructions supplied. Abit more detailed.

this is the task….preparing a hole and installing this 10mm bolt thru your upper sub-frame right about here. You�ll need to prepare (align, and step drill) the hole for install. That�s were thing can go wrong real fast. The installation part has a few issues also.

10 mm Bolt shank diameter = .3935 inch

bolt size = M10-1.5 Metric coarse thread, self locking nut included in 24.99 kit

bolt length 5.5 inches or 140 mm as shown. Those are the 2x drills provided in the Drill thru kit. The Bushing was also provided.

Smaller drill size = .3085 inch

larger drill size =.4025 inch. Remember bolt is .3935 inch. This will be a “clearance fit” fastener with .009 inch clearance. The Hole fill would be considered a “Class II”.

a view of the kit supplied bushing. This will go on the nut side of the bolt. It is not part of the drilling process

from the right side of the bike, loosen the clamp holding the carb intake boot. Use phillips screw driver and un-thread till clamp does not bind boot connection.

loosen the lower sub frame bolts 1x full turn, remove the upper sub-frame bolts. Remove both of them. It’s ok your frame will not collaspe.

grab the rear rack and gently push it back. Use a rocking motion. Keep and eye on your wire harness, exhaust, and carb boot. Your sub-frame will pivot about the lower bolts. Push enough so you have enough room to work those drill bits into the bike main spine upper frame holes

about this much. Now stop and secure your frame. I tightend the lower bolts abit. Your kinda stretching your wire bundles. So be careful! Right side of bike shown here

left side of bike shown here. Thats enough room to get your drill in there.

rubber boot comes off carb. No worries it will go back on easy

mask off area with rags to catch chips….Lots and lots of oily messy steel chips. Remember your carb inlet is exposed. Tape around that exposed area. Then tape again. If chips get in there, you may need a carb rebuild to remove those shavings and thats another story

start with the smaller drill in kit. Try to keep bit level and �pick-up� threaded hole. Go slow! Use cutting fluids on tip so it does not get hot. If you see smoke from fluid, your going too fast. Should take you about 15 min with just this bit to go 1/2 way thru. Then goto other side and repeate till the holes connect in the center. No turning back now sparky!

another view of drilling operation. Slow and steady, pull drill back about every 60 sec to re-lub and vacuum chips. Use magnet also to clear chips.

Once you are about 1/2 way thru, You�ll need to switch sides and start on opposite side. Hopefully, the holes will align. Mine did Whew!

hole is drilled thru with the .3085 inch diameter drill. Will need to open up to .4025 inch.

pass one done

use shop vac to pick up chips

I had difficulty starting the �big� drill, so I opted to use an intermediate size step drill method to remove a bit more. The center drill is .342 inch. This step made the last drilling operation easier.

step drill

final drill

bolt fits here. Slides in easy

like this, thread side extending

now I need to open up these 2x remaining holes on sub-frame.

same process, much easier this time…use compressed air and magnet to remove chips from work area. Realign the frame holes now. Easy, just pull rack forward. Check that carb boot engages back on carb. Inspect muffler also. It may have came loose

We will need some of that high quality waterproof marine grease. This will assist in resisting joint/bolt galling and more importantly assist in preventing water ingress into these closed-out joints.

That�s the stuff I�m talking about sparky!

lube that bolt with waterproof grease

like this

work it in

needed to give a few taps with hammer, as drilled holes were not perfect aligned

all the way in

thread side

place that bushing in thru threads. Mine did not fit. Needed to grind and open it�s hole abit.

engage that self locking nut. No loc tight needed with this nut. Torque to 33 ft-lbs. Re-tighten that carb boot, retorque those lower subframe bolts to 18 in-lbs. Use red loc-tight on those.

humm….I have 4x extra sub-frame bolts available…I could give them away or…let me check the size of these foot peg fasteners

8.8 grade..not too bad

12.9 is 50% stronger material for same diameter

length = 30 mm

30 mm here too!

same diameter and thread. Whoo hoo!

check torque. Torque to 13.5 ft-lbs

prep fasteners for installation. May need to remove these at some point so Blue loc-tite is best for this application

install foot pegs with new improved cap style fasteners

more bolts for the collection cup

work area when finished….What a mess…
Kit review and lessons learned:
1. The upgrade gives piece of mind that no sub-frame failures will occur over the bikes life
2. I would recommend the �drill thru� mod only for those with machine shop experience
3. I would recommend the $5.00 kit for those not confident in the drill thru mod. You still gain a 20% increase in sub-frame strength.
4. I would recommend upgrading your foot pag fasteners with the 12.9 cap style.
5. Although my install was successful, may things can go wrong, such as:
5a drill breaks in hole
5b chips get into carb inlet
5c holes do not align
5d overheat the steel frame and change the temper of the material
6. The drill thru mod effectively doubles the upper sub frame fastener strength and increases the lower sub-frame strength by 20%.
If I had to do this again I would:

study up on drilling

Add an additional step drill. 3x steps total. The last drill would be a size W or .385 inch

Then final cut step would be with a piloted reamer. A piloted reamer gives a mirror like surface finish of an RHR of 32. The reamer has a pilot of .385 inch and a final cut size of .4005 inch

use cutters like these designed to open up holes in steel. See the reamer here:
http://www.panamericantool.com/productlstR.cfm?cat=H.S.S.%20Piloted%20Chucking%20 Reamers%20-%20Straight%20Shank,%20Straight%20Flute&fam=HIGH%20SPEED%20STEEL%20REAMERS
see part # 99-708 The reamer costs $20.00 and is 7 inches long
You can buy these 12.9 grade bolts here: http://www.boltdepot.com/dimension.a…25&cs=81&cm=23
fork me I�m done!