88 Turbo shaft play

Discussion of Corvette based Callaway Cars including: 1987-1991 RPO B2K Callaway Twin Turbo Corvettes (C4); Callaway SuperNatural Corvettes (CL-1/CR-1); Callaway C12; Supercharged Corvettes; Callaway C16; 6th Generation Callaway Corvettes (SC560, SC580, SC606, SC616, SC620, SC652); 7th Generation Callaway Corvettes (SC627/SC757); NEW Callaway C8 Corvettes - and more!
Post Reply
User avatar
Cski68
1-PSI
1-PSI
Posts: 12
Joined: Fri Jun 02, 2017 3:08 pm
Location: Vargön Sweden
Contact:

88 Turbo shaft play

Post by Cski68 »

Hello,
I've removed one of my turbos along with the header to do a little clean up and noticed there is, what I would consider, a lot of play in the shaft. Does anyone know how much, if any, play should be in the shaft? Also, can I get a rebuild kit for this or is it better to have it done professionally?
Regards,
Chris
Chris
1988 Callaway twin turbo #34
1973 Corvette Stingray Convertible BB
User avatar
SurfnSun
Site Admin
Site Admin
Posts: 2331
Joined: Wed Aug 27, 2008 9:44 pm
Location: Central FL
Contact:

Re: 88 Turbo shaft play

Post by SurfnSun »

My understanding is there should be no shaft play at all. Your best bet is going to be the source an aftermarket turbo and weld a new flange on to your existing manifold. The reason for this is there are no more soft parts to be had for the rotomaster RM26 turbos.

I think from a size perspective the Garrett GT 28 will fit but it's going to take some work from the flange on the log manifold as well as the flange at the backside of the Turbo.
User avatar
Cski68
1-PSI
1-PSI
Posts: 12
Joined: Fri Jun 02, 2017 3:08 pm
Location: Vargön Sweden
Contact:

Re: 88 Turbo shaft play

Post by Cski68 »

Thanks for the Reply,
I read in one of your earlier posts you mentioned that the Rajay rebuild kit works with the RM26 because they were developed in conjunction with rotomaster. Has that been verified? I really don't want to go custom if I can avoid it.
Chris
1988 Callaway twin turbo #34
1973 Corvette Stingray Convertible BB
User avatar
Cski68
1-PSI
1-PSI
Posts: 12
Joined: Fri Jun 02, 2017 3:08 pm
Location: Vargön Sweden
Contact:

Re: 88 Turbo shaft play

Post by Cski68 »

I got a reply from Grumpys Performance and this is what he responded with;

INSPECTION

Visually inspect the turbocharger and exhaust manifold gasket surfaces. Replace stripped or eroded mounting studs.



Visually inspect the turbocharger for cracks. The following cracks are NOT acceptable:

Cracks in the turbine and compressor housing that go completely through.

Cracks in the mounting flange that are longer than 15 mm (0. 6 in. ).

Cracks in the mounting flange that intersect bolt through-holes.

Two (2) Cracks in the mounting flange that are closer than 6. 4 mm (0. 25 in. ) together.

Visually inspect the impeller and compressorwheel fins for nicks, cracks, or chips. Note: Some impellers may have a factory placed paint mark which, after normal operation, appears to be a crack. Remove this mark with a suitable solvent to verify that it is not a crack.

Visually inspect the turbochargercompressor housing for an impeller rubbing condition (Inspect Compressor Housing for Impeller Rubbing Condition). Replace the turbocharger if the condition exists.

Measure the turbocharger axial end play:

Install a dial indicator as shown in (Measure Turbocharger Axial End Play). Zero the indicator at one end of travel.

Move the impeller shaft fore and aft and record the measurement. Allowable end play is 0. 026 mm (0. 0001 in. ) MIN. and 0. 127 mm (0. 005 in. ) MAX. If the recorded measurement falls outside these parameters, replace the turbocharger assembly.

Measure the turbocharger bearing radial clearance:

Insert a narrow blade or wire style feeler gauge between the compressorwheel and the housing (Measure Turbocharger Bearing Radial Clearance).

Gently push the compressorwheel toward the housing and record the clearance.

With the feeler gauge in the same location, gently push the compressorwheel away from the housing and again record the clearance.

Subtract the smaller clearance from the larger clearance. This is the radial bearing clearance.

Allowable radial bearing clearance is 0. 33 mm (0. 013 in. ) MIN. and 0. 50 mm (0. 020 in. ) MAX. If the recorded measurement falls outside these specifications, replace the turbocharger assembly.


My turbos shaft play looked more like the new turbo in the first video but I put a dial indicator to it and the end play is .0035 in. and the bearing radial clearance is .3mm ( .05mm at the closest point to the housing and .35mm when pushed away from the housing) so it seams my Turbos aren't as bad off is I thought.
Chris
1988 Callaway twin turbo #34
1973 Corvette Stingray Convertible BB
User avatar
SurfnSun
Site Admin
Site Admin
Posts: 2331
Joined: Wed Aug 27, 2008 9:44 pm
Location: Central FL
Contact:

Re: 88 Turbo shaft play

Post by SurfnSun »

Cski68 wrote: Sun Jun 11, 2017 5:38 am Thanks for the Reply,
I read in one of your earlier posts you mentioned that the Rajay rebuild kit works with the RM26 because they were developed in conjunction with rotomaster. Has that been verified? I really don't want to go custom if I can avoid it.
It has not been verified. I've only had one person tell me that. Someone will need to test it at a point. For my money I'd go thru the custom headache once and have a better replaceable ball bearing turbo.
Post Reply