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Flywheel -Clutch swap

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Flywheel -Clutch swap
#1
  This topic is about my 1973 Triumph Spitfire 1500
teeka56 Avatar
teeka56 mike leisner
Seattle, WA, USA   USA
I have a small journal 1296 ( 1968) that I am going to mount a J type overdrive transmission (1980) behind. My question is can I put a 1500 flywheel / late clutch on the SJ 1296. I see where Rimmers sells the spacers for the bolt size in the crank change, is this all that is needed?

Alternative would be to have the SJ flywheel drilled for larger late clutch.

Thanks, mike

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spitlist Avatar
spitlist Joe Curry
Sahuarita, Sahuarita, AZ, USA   USA
I used to have a 1500 clutch on my small journal 1296, but in my case I used an aluminum flywheel that was especially made for that purpose.

I replaced it with the original Mk3 Spit flywheel and clutch when I mounted that engine in my Street Spit because the light flywheel wasn't particularly easy to drive on the street. It tended to buck at low speeds owing to the lack of weight.

teeka56 Avatar
teeka56 mike leisner
Seattle, WA, USA   USA
Great, thanks for the quick answer!
Mike

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14GPDJENGINEERING Avatar
Silver Spring, MD, USA   USA
Just find a 20 spline 6 1/2 inch disk?



Dennis smiling smiley

grumpicus Steve Jackson
Leicester, Leicestershire, UK   GBR
In reply to # 1511219 by 14GPDJENGINEERING Just find a 20 spline 6 1/2 inch disk?

The Triumph Dolomite 1300 saloon/sedan (around 1976 to 1980) used a clutch friction plate that fits the bill! It was the only 1300 Triumph fitted with the single rail box, and retained the 6.5" clutch & matching flywheel. The clutch friction plate had the correct 20 splines, and had the part number GCP244. The only problem is that they are getting difficult to find....

It's true that the 1500 flywheel can be fitted, and Rimmers sell the sleeves to enable it to fit to the 1300 crank, using the existing 3.8" UNF bolts. As the sleeves only serve to locate the flywheel, it means that unless plain 3/8" washers are fitted under the heads of the retaining bolts, only the outer section of the underside of the bolt head is actually holding the flywheel in place. Added to that, the 1500 flywheel is heavier, and obviously has greater inertia. Early 1500 engines did have the 7.25" diameter clutch held in place with 3/8" UNF bolts, but the clearance holes on those flywheels were only 3/8" diameter, and sleeves were not needed. Later engines used 7/16" clearance holes in the flywheel, and 7/16" UNF bolts - which were torqued to a much higher figure than the 3/8" bolts.

It may be apparent that I don't like the solution using the sleeves - sure, it's unlikely that the 3/8" bolts will give way, but it's a scheme that eats into the safety margins. My preference is to get the crank mounting holes drilled & tapped to 7/16" UNF, and fit the later 1500 flywheel with the larger bolts, torqued up to around 75ft.lb. (It is possible to drill and tap the crank with the engine in place, but I don't advise it, based on personal experience!)

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1511236 by grumpicus
In reply to # 1511219 by 14GPDJENGINEERING Just find a 20 spline 6 1/2 inch disk?

The Triumph Dolomite 1300 saloon/sedan (around 1976 to 1980) used a clutch friction plate that fits the bill! It was the only 1300 Triumph fitted with the single rail box, and retained the 6.5" clutch & matching flywheel. The clutch friction plate had the correct 20 splines, and had the part number GCP244. The only problem is that they are getting difficult to find....

It's true that the 1500 flywheel can be fitted, and Rimmers sell the sleeves to enable it to fit to the 1300 crank, using the existing 3.8" UNF bolts. As the sleeves only serve to locate the flywheel, it means that unless plain 3/8" washers are fitted under the heads of the retaining bolts, only the outer section of the underside of the bolt head is actually holding the flywheel in place. Added to that, the 1500 flywheel is heavier, and obviously has greater inertia. Early 1500 engines did have the 7.25" diameter clutch held in place with 3/8" UNF bolts, but the clearance holes on those flywheels were only 3/8" diameter, and sleeves were not needed. Later engines used 7/16" clearance holes in the flywheel, and 7/16" UNF bolts - which were torqued to a much higher figure than the 3/8" bolts.

It may be apparent that I don't like the solution using the sleeves - sure, it's unlikely that the 3/8" bolts will give way, but it's a scheme that eats into the safety margins. My preference is to get the crank mounting holes drilled & tapped to 7/16" UNF, and fit the later 1500 flywheel with the larger bolts, torqued up to around 75ft.lb. (It is possible to drill and tap the crank with the engine in place, but I don't advise it, based on personal experience!)

An important correction:
The bolts DO NOT 'locate the flywheel' to the crankshaft, that is the job of the DOWEL PIN.
The flywheel bolt shanks are not precision ground, and so the fit into the holes in the flywheel is also not precision.
The dowel pin OTOH is precision ground, to provide a precision fit with the flywheel holes and crankshaft holes.
I do agree that hardened washers are a good idea, especially with an aluminum flywheel.

spitlist Avatar
spitlist Joe Curry
Sahuarita, Sahuarita, AZ, USA   USA
You should contact Ted Schumacher http://www.tsimportedautomotive.com/.

He has always proven to be a valuable resource in finding Mix/Match parts.

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grumpicus Steve Jackson
Leicester, Leicestershire, UK   GBR
Correction accepted - so if the sleeves around the 3/8” bolts aren’t serving to locate the flywheel, what exactly are they doing? Not a lot, probably - they aren’t transmitting torque, that’s done by the clamping of the flywheel to the crank by the 3/8” bolts. Might as well leave them out, then.....

spitlist Avatar
spitlist Joe Curry
Sahuarita, Sahuarita, AZ, USA   USA
In reply to # 1511276 by grumpicus Correction accepted - so if the sleeves around the 3/8” bolts aren’t serving to locate the flywheel, what exactly are they doing? Not a lot, probably - they aren’t transmitting torque, that’s done by the clamping of the flywheel to the crank by the 3/8” bolts. Might as well leave them out, then.....

They are securing the flywheel to the crank. I think we have gotten into a semantics discussion more than anything.

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clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1511276 by grumpicus Correction accepted - so if the sleeves around the 3/8” bolts aren’t serving to locate the flywheel, what exactly are they doing? Not a lot, probably - they aren’t transmitting torque, that’s done by the clamping of the flywheel to the crank by the 3/8” bolts. Might as well leave them out, then.....

Psychological support?
Using the sleeves somehow 'feels right', to me anyway.

Once could add additional dowels, this was a common mod done to air cooled VW motors that had been hot-rodded.

But here's another way to consider:
Use connecting rod alignment bushings to augment the single existing dowel.
These have precision ground OD, so they achieve a precision fit into a properly sized hole.
There are two common sizes, for 3/8" bolts and 7/16" bolts.

They can be fitted with the engine in the car (transmission removed of course) with this procedure:

Remove and machine the bolts one at a time.
The other 3 bolts will keep the flywheel and crankshaft tightly clamped (by about 12,000 lb force for 3/8" bolts) into alignment without the possibility of shifting.
Use a drill slightly smaller than the nominal OD to drill out the hole, through the flywheel and to a depth of perhaps 1/8" into the crankshaft 'hub'.
Then use a straight machine reamer to finish the hole to size.
Blow away any swarf or debris with compressed air, and lightly lubricate the hole.
Now drive the bushing all the way home, using a piece of drill rod matching the OD.
The installed bushing will span the joint between the flywheel and the crankshaft 'hub'

Replace that bolt and torque to spec, and move on to the next one.

When completed, you will have the flywheel located to the crankshaft by 4 precision bushings and 1 dowel.

grumpicus Steve Jackson
Leicester, Leicestershire, UK   GBR
In reply to # 1511290 by clshore
In reply to # 1511276 by grumpicus Correction accepted - so if the sleeves around the 3/8” bolts aren’t serving to locate the flywheel, what exactly are they doing? Not a lot, probably - they aren’t transmitting torque, that’s done by the clamping of the flywheel to the crank by the 3/8” bolts. Might as well leave them out, then.....

Psychological support?
Using the sleeves somehow 'feels right', to me anyway.

Once could add additional dowels, this was a common mod done to air cooled VW motors that had been hot-rodded.

But here's another way to consider:
Use connecting rod alignment bushings to augment the single existing dowel.
These have precision ground OD, so they achieve a precision fit into a properly sized hole.
There are two common sizes, for 3/8" bolts and 7/16" bolts.

They can be fitted with the engine in the car (transmission removed of course) with this procedure:

Remove and machine the bolts one at a time.
The other 3 bolts will keep the flywheel and crankshaft tightly clamped (by about 12,000 lb force for 3/8" bolts) into alignment without the possibility of shifting.
Use a drill slightly smaller than the nominal OD to drill out the hole, through the flywheel and to a depth of perhaps 1/8" into the crankshaft 'hub'.
Then use a straight machine reamer to finish the hole to size.
Blow away any swarf or debris with compressed air, and lightly lubricate the hole.
Now drive the bushing all the way home, using a piece of drill rod matching the OD.
The installed bushing will span the joint between the flywheel and the crankshaft 'hub'

Replace that bolt and torque to spec, and move on to the next one.

When completed, you will have the flywheel located to the crankshaft by 4 precision bushings and 1 dowel.

Agreed, but unless plain (preferably hardened) steel washers are fitted between the 3/8" bolts and the flywheel, only the outer part of the underside of the bolts is transmitting the clamping force to the flywheel, due to the 7/16" clearance holes., Not good engineering practice, IMHO.

teeka56 Avatar
teeka56 mike leisner
Seattle, WA, USA   USA
Very good discussion . Thanks for the tip on the rare clutch. I do have access to a very good machinist.
And as it turns out I do have a early '73 1500- so maybe I have a 3/8 flywheel with larger clutch! Will know when I pull that motor to replace with SJ 1296.

Mike

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1511347 by grumpicus
In reply to # 1511290 by clshore
In reply to # 1511276 by grumpicus Correction accepted - so if the sleeves around the 3/8” bolts aren’t serving to locate the flywheel, what exactly are they doing? Not a lot, probably - they aren’t transmitting torque, that’s done by the clamping of the flywheel to the crank by the 3/8” bolts. Might as well leave them out, then.....

Psychological support?
Using the sleeves somehow 'feels right', to me anyway.

Once could add additional dowels, this was a common mod done to air cooled VW motors that had been hot-rodded.

But here's another way to consider:
Use connecting rod alignment bushings to augment the single existing dowel.
These have precision ground OD, so they achieve a precision fit into a properly sized hole.
There are two common sizes, for 3/8" bolts and 7/16" bolts.

They can be fitted with the engine in the car (transmission removed of course) with this procedure:

Remove and machine the bolts one at a time.
The other 3 bolts will keep the flywheel and crankshaft tightly clamped (by about 12,000 lb force for 3/8" bolts) into alignment without the possibility of shifting.
Use a drill slightly smaller than the nominal OD to drill out the hole, through the flywheel and to a depth of perhaps 1/8" into the crankshaft 'hub'.
Then use a straight machine reamer to finish the hole to size.
Blow away any swarf or debris with compressed air, and lightly lubricate the hole.
Now drive the bushing all the way home, using a piece of drill rod matching the OD.
The installed bushing will span the joint between the flywheel and the crankshaft 'hub'

Replace that bolt and torque to spec, and move on to the next one.

When completed, you will have the flywheel located to the crankshaft by 4 precision bushings and 1 dowel.

Agreed, but unless plain (preferably hardened) steel washers are fitted between the 3/8" bolts and the flywheel, only the outer part of the underside of the bolts is transmitting the clamping force to the flywheel, due to the 7/16" clearance holes., Not good engineering practice, IMHO.

I agree 100% (see post #6).

billspit Bill Kea
Moore, Spartanburg, SC, USA   USA
I installed a 1500 flywheel on my Mk I Spitfire using the afore mentioned sleeves. I have had no problems. I did this to use the 1500 OD transmission I bought, so naturally, I used a 1500 clutch. BTW, the sleeves I used are the same used in the rear diff to locate the bearing caps.

stage3 Avatar
stage3 Christian P
Saarbrücken, Saarland, Germany   DEU
Hi Mike,

I have been running the combination of 1296 engine and singel-rail gearbox for nearly 20 years in my Spitfire. For me the easiest way was to use a 6.5" fine spline clutch disk from a 1300 Toledo (I think). It is still available as I bought another one last year from a dealer here in Germany (Bastuck), albeit a bit more expensive than the standard clutch discs.

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