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Bell Housing Dowl Pins


silverstar
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Alright guys you helped me out before and now i have another question for the pros. I am doing a 68 DM600, pulled out my 673e and installing a 675, i am keeping my quad box trans so i have to keep my old bell housing. Question is the dowl pins that would center my bell housing have slop in them. I have heard that you are supposed to install it and put a dial indicator on the crank to make sure it is centered, then just tighted the bolts. In my mind doing this would work but wouldnt this put all the stress on just the torq of the bell housing bolts, dont you need the dowls to actualy support and keep the motor from shifting? As always any input would be great and if you need more info let me know. Thanks

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Alright guys you helped me out before and now i have another question for the pros. I am doing a 68 DM600, pulled out my 673e and installing a 675, i am keeping my quad box trans so i have to keep my old bell housing. Question is the dowl pins that would center my bell housing have slop in them. I have heard that you are supposed to install it and put a dial indicator on the crank to make sure it is centered, then just tighted the bolts. In my mind doing this would work but wouldnt this put all the stress on just the torq of the bell housing bolts, dont you need the dowls to actualy support and keep the motor from shifting? As always any input would be great and if you need more info let me know. Thanks

Yes, you are correct to the point of dial indicating the bell housing to get on center and tighten the bolts. The dowl pins are critical in the support of the bell housing and transmission. After centering the bell housing and tightening the bolts, you should purchase a new pair of oversized dowl pins. Then redrill and ream existing dowl pin holes in motor and bell housing to within .002 to .003 smaller then new dowl pins diameter. This will allow you to drive new dowl pins in their bore tightly.

Note: Check bell housing face (engine side) for any wear due to previous loosening. If so, I suggest having bell housing machined to remove any wear and true up. Also check back of engine block for the same problem.

Hope this helps!

B-Model Chet

OLD SCHOOL

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Yes, you are correct to the point of dial indicating the bell housing to get on center and tighten the bolts. The dowl pins are critical in the support of the bell housing and transmission. After centering the bell housing and tightening the bolts, you should purchase a new pair of oversized dowl pins. Then redrill and ream existing dowl pin holes in motor and bell housing to within .002 to .003 smaller then new dowl pins diameter. This will allow you to drive new dowl pins in their bore tightly.

Note: Check bell housing face (engine side) for any wear due to previous loosening. If so, I suggest having bell housing machined to remove any wear and true up. Also check back of engine block for the same problem.

Hope this helps!

B-Model Chet

I'll second that.

Keeping the bellhousing true and tight is critical beacause a loose or misaligned bellhousing will result in tearing the center out of the clutch disc or discs depending on whether you have a single disc or double disc clutch.

.

"If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

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Alright guys you helped me out before and now i have another question for the pros. I am doing a 68 DM600, pulled out my 673e and installing a 675, i am keeping my quad box trans so i have to keep my old bell housing. Question is the dowl pins that would center my bell housing have slop in them. I have heard that you are supposed to install it and put a dial indicator on the crank to make sure it is centered, then just tighted the bolts. In my mind doing this would work but wouldnt this put all the stress on just the torq of the bell housing bolts, dont you need the dowls to actualy support and keep the motor from shifting? As always any input would be great and if you need more info let me know. Thanks

Is there a reason you can't use the flywheel housing that is on the 675 engine? terry
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Is there a reason you can't use the flywheel housing that is on the 675 engine? terry

terry, yes, the reason is the 675 was mated to a 5 speed transmission, this bellhousing is totaly different than my trans ( i want to keep). My transmission is a quadbox, duplex or triplex ( not sure how to tell), it runs a single disk clutch, the 5 speed bell housing is deeper (to accept a 2 disk clutch)and the bolts are actually differnt size to. Side not: my trans has 1-5 plus reverse on one stick (closest to leg) the other stick has lo-lo, lo, and direct on the other stick ( farthest from you). thanks aga

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Yes, you are correct to the point of dial indicating the bell housing to get on center and tighten the bolts. The dowl pins are critical in the support of the bell housing and transmission. After centering the bell housing and tightening the bolts, you should purchase a new pair of oversized dowl pins. Then redrill and ream existing dowl pin holes in motor and bell housing to within .002 to .003 smaller then new dowl pins diameter. This will allow you to drive new dowl pins in their bore tightly.

Note: Check bell housing face (engine side) for any wear due to previous loosening. If so, I suggest having bell housing machined to remove any wear and true up. Also check back of engine block for the same problem.

Hope this helps!

B-Model Chet

do i have to bolt the bell housing first then drill? is it possible to have pins machined so that they are tight in the block(on size) and a different size in the bell housing? I used to be in the machine shop trade so i do have the ability. Now if this is not a good idea feel free to say. I just hate to drill and ream if i can get around it. Thanks again for all the help.

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As a point, I've always done (and have been told) that the bell housing should be .002 or less.

Remember that the pilot bearing is the front bearing on the transmission input shaft.

Perfect is just barely good enough!!

Packer

Keep a clutchin'

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do i have to bolt the bell housing first then drill? is it possible to have pins machined so that they are tight in the block(on size) and a different size in the bell housing? I used to be in the machine shop trade so i do have the ability. Now if this is not a good idea feel free to say. I just hate to drill and ream if i can get around it. Thanks again for all the help.

You hang the bellhousing, put the bolts in just snug enough sou you can adjust it, then dial indicate it so it's concentric with the crank, tighten the bolts (use loctite), then ream the dowel pin holes and insert them.

The reason for drilling & reaming to an oversize is that the dowel pin holes in the housing and the block may not be perfectly lined up once your housing is dial indicated to that engine block.

.

"If You Can't Shift It Smoothly, You Shouldn't Be Driving It"

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Sounds like your transmission is the TRTX670 10 speed overgear Triplex.I have the same trans. in 2 of my B-53's.

I asked this in another topic, not sure if you posted or not, but since you have one. will this trans hold up to a 675 motor with a single disk clutch?

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Yes, you are correct to the point of dial indicating the bell housing to get on center and tighten the bolts. The dowl pins are critical in the support of the bell housing and transmission. After centering the bell housing and tightening the bolts, you should purchase a new pair of oversized dowl pins. Then redrill and ream existing dowl pin holes in motor and bell housing to within .002 to .003 smaller then new dowl pins diameter. This will allow you to drive new dowl pins in their bore tightly.

Note: Check bell housing face (engine side) for any wear due to previous loosening. If so, I suggest having bell housing machined to remove any wear and true up. Also check back of engine block for the same problem.

Hope this helps!

B-Model Chet

O.k. sounds good. Now how do i find the center of crank to place my indicator? If i use a magnetic base on the back of the crank how do i know if i am truly center of crank. Do they make a speacial tool or bushing. thanks

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hi,

What has been said already is 100 percent true, but when I did the same thing on my b 61 I installed the old bellhousing on to the 675 engine the dowel pin on the old engine were much larger than the newer engine. I machined the old dowel pins from the 673 engine to have a step in them so one side fit the bellhousing and the other fit the engine. Installed the bellhousing and removed the injectors from the engine so I could rotate it easier. The bellhousing was almost perfect. The only reason I did it this way is because I thought it was close before and that it maybe it would check ok again without alot of indicating to center the bellhousing, There is a tool to mount the indicator to crank.

Morgan

15 gears...no waiting!
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